Dissertations / Theses: 'Epilepsy Magnetic Resonance Imaging'

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Wieshmann, Udo Carl. "New MR imaging techniques in epilepsy." Thesis, University College London (University of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313614.

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Alonazi, B. K. "A prospective advanced magnetic resonance imaging study of newly diagnosed epilepsy." Thesis, University of Liverpool, 2017. http://livrepository.liverpool.ac.uk/3008153/.

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According to the World Health Organization (WHO), approximately 50 million people in the world have active epilepsy. Epilepsy is the most common neurological disorder after migraine, stroke and Alzheimer’s disease. Epilepsy disorder affects men and women of all ages, races and social classes. There is an extensive neuroimaging literature describing patients with chronic epilepsy. However, few studies have investigated brain structural changes in patients with newly diagnosed epilepsy (NDE) using quantitative magnetic resonance imaging (MRI). The main goal of this thesis was to determine the nature and extent of brain structural and functional differences in patients with NDE using different MRI techniques compared with healthy controls. The first study was to determine the morphometric changes in patients with NDE compared to healthy controls using quantitative MRI analysis. The second study was to identify functional connectivity differences (in the whole brain and regions of interest) in patients with NDE and healthy controls using resting state functional magnetic resonance imaging (RS-fMRI). All study participants were recruited from the Walton Centre NHS Foundation Trust, Liverpool. All had been diagnosed with focal epilepsy by a consultant neurologist and recruited for MRI scanning within 12 months of diagnosis. Twenty-seven patients with NDE were recruited (14 male, 13 female, with mean age (M)=33.2) and 32 healthy matched controls (14 male, 18 female, M=33.07).Control and NDE study participants were matched for age, handedness and gender. All participants were scanned using a Siemens 3T Trio whole-body scanner (Siemens, Erlangen, Germany) with eight-channel radiofrequency (RF) head coil together with foam padding to comfortably restrict head motion at the Magnetic Resonance and Image Analysis Research Centre (MARIARC), University of Liverpool. Various MRI sequences were conducted including: 3D MPRAGE T1-weighted anatomical data, and RS-fMRI In the first study, shape, surface based, and voxel based morphometry analysis were applied, and the results suggested differences to the morphology of the brain stem and both the right and left thalami in patients with NDE. The independent component analysis of RS-fMRI showed abnormal different functional connectivity in visual and attention networks in patients with NDE relative to healthy controls while ROI-ROI demonstrated increased functional connectivity between the subcallosal cortex and both thalami in NDE patients. This is the first extensive programme of research to employ various analysis techniques and advanced MRI sequences to study structural and functional differences in patients with NDE compared to healthy controls. The results of this thesis show that structural and functional differences occur in both thalami in patients with NDE. These findings suggest that the thalamus plays a very important role in epilepsy pathophysiology. The results of this thesis offer further understanding regarding the role of structural and functional differences in NDE. They highlight the need for future quantitative MRI analysis studies of NDE to help patients avoid the chronic stage of the disorder and improve their quality of life.

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Centeno, Soladana Maria. "Magnetic resonance imaging in epilepsy. Functional and structural imaging in frontal lobe epilepsy and language study in bilingual patients." Doctoral thesis, Universitat Autònoma de Barcelona, 2016. http://hdl.handle.net/10803/386529.

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Gracias al desarrollo de las técnicas de neuroimagen en las últimas décadas se han conseguido avances importantes en el conocimiento de la epilepsia y sus mecanismos; descubriéndose cuestiones calves que han modificado conceptos clásicos y generado nuevas hipótesis en este campo. En los trabajos que componen esta tesis doctoral se utiliza como herramienta común la resonancia magnética para investigar varios aspectos que comprenden desde la función cognitiva a aspectos estructurales. En concreto se han empleado técnicas de resonancia magnética funcional y análisis cuantitativo de imagen estructural para responder a las hipótesis planteadas en los distintos trabajos que la conforman. La tesis comprende tres estudios: los dos primeros se centran en la epilepsia frontal y el tercero en mapeo de lenguaje pacientes bilingües con epilepsia. La epilepsia frontal (EF) es el segundo síndrome más prevalente dentro de las epilepsias focales, después de la epilepsia temporal. Sin embargo, debido a su complejidad como grupo, existen pocos estudios concluyentes a cerca de la función cognitiva en estos pacientes. Tampoco se conocen los cambios funcionales en las redes cognitivas que subyacen los déficits cognitivos en este grupo. Comprender estos aspectos contribuiría de manera importante a entender los déficits cognitivos en este grupo así como a comprender las alteraciones causadas por la cirugía. El primer trabajo de esta tesis estudia la memoria a largo plazo en pacientes con EF. Existen datos contradictorios sobre los déficits de memoria en pacientes con EF. Esta función ha sido poco explorada a pesar de la prevalencia de problemas de memoria en este grupo. Utilizando un paradigma de memoria en resonancia magnética funcional se caracterizaron los cambios funcionales secundarios a la epilepsia frontal y las alteraciones que se asocian al deterioro de esta función. En el segundo trabajo sobre epilepsia frontal se explora la presencia de cambios estructurales en sustancia gris en pacientes con EF. A diferencia de los pacientes con epilepsia temporal, en este grupo no existen estudios que exploren de manera cuantitativa cambios comunes en la estructura de la sustancia gris. Para ello se han empleado técnicas cuantitativa voxel por voxel que son altamente sensibles a cambios no identificables con inspección visual. La resonancia funcional (RMf) de lenguaje se ha integrado como parte importante de los estudios pre quirúrgicos en epilepsia. Esta necesidad se ve justificada por la alta incidencia de lateralización atípica del lenguaje en este grupo de pacientes. Este test se ha validado clínicamente en su mayoría utilizando la lengua nativa de los sujetos. Cuando el test se realiza en una segunda lengua como es el caso de población inmigrante se plantea la cuestión de la validez del test. Aunque existen un gran número de estudios de bilingüismo utilizando RMf, estos se han centrado en la búsqueda de diferencias en redes neuronales de las diferentes lenguas y no en el análisis de la validez clínica de estos mapas. En el tercer trabajo de la tesis se investiga las diferencias en los mapas de lenguajes obtenidos con RMf cuando se utiliza la lengua materna y cuando se utiliza una lengua secundaria. Con este estudio pretendemos evaluar la validez clínica de realizar mapeo de lenguaje con resonancia en una lengua secundaria.
Imaging techniques have led to the discovery of key questions in the field of epileptology. In this thesis, functional and structural aspects of focal epilepsies are investigated through magnetic resonance imaging (MRI). In particular, functional MRI and voxel wise analysis are used as the tool to test the hypothesis posed in the different studies that conform this thesis. The thesis is divided into three studies; two of them focus on frontal lobe epilepsy and the third one on language mapping of bilingual patients with epilepsy. Frontal lobe epilepsy is the second most prevalent syndrome among the focal epilepsies after temporal lobe epilepsy. However, it has proved challenging to characterize cognitive dysfunction within this group. Furthermore, the functional anatomy correlates of dysfunction in FLE is still unknown. Understanding these changes may help to characterize better the cognitive profile of this group. It may also improve the understanding of the changes in cognitive function as the result of surgery. In particular one of the studies focuses in memory function in patients with FLE. This cognitive aspect has received little attention in this group of patients. However, there is a significant prevalence of memory deficits in patients with Frontal lobe epilepsy. Using functional MRI (fMRI) I investigated long term memory in patients with FLE in order to characterize the functional anatomy that underlies memory dysfunction in this group of patients. The second study on FLE explores the structural changes in this syndrome. It uses voxel wise quantitative MRI techniques to identify common structural changes across this heterogeneous group. Language fMRI is widely used as part of the pre-surgical investigations of patients with drug resistant epilepsy. This is justified given the high prevalence of atypical language dominance in patients with epilepsy. The clinical validation of these tests have been performed using the subject’s native language. However this is a problem when the evaluated subject has to perform the test in a secondary language as it is the case of immigrant population. Although there is a large number of fMRI studies in bilingualism, these mainly focus in the differences in language networks between the different languages in bilinguals. The third study in this thesis investigates the differences in the language networks that support native and learned languages in bilingual patients with epilepsy and asses the clinical validity of mapping language using language paradigms in a subject’s first and second languages.

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Tierney, T. M. "Development and application of functional magnetic resonance imaging in paediatric focal epilepsy." Thesis, University College London (University of London), 2017. http://discovery.ucl.ac.uk/1545153/.

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There are two major applications of fMRI in paediatric focal epilepsy. The first is mapping of eloquent cortex. The second is the use of simultaneous EEG-fMRI to map the epileptogenic zone. The main methodological issues faced by these fMRI applications are: motion, physiological noise, quality assurance, and statistical analysis. To address the issues of subject motion and physiological noise we constructed a simple analytical biophysical model of Blood Oxygenation Level Dependent (BOLD) signal capable of identifying and correcting these artefacts (named FIACH). This model was validated in a sample of children performing a language task with high motion levels. FIACH outperformed 6 other competitive methods of noise control. In the second study, we characterized how metrics of quality assurance could predict the clinical utility of EEG-fMRI. We also quantified the impact of a natural stimulus (a cartoon) on reducing subject motion. During this analysis it was noted that the corrections for multiple comparisons employed using Random Field Theory (RFT) at an individual level were overly conservative. This led to an exploration of RFT sensitivity and its relationship to image smoothing and degrees of freedom. By reviewing over 150 papers published in 2016 it was possible to estimate that 80% of studies suffer from a similar loss in sensitivity. Simulations are provided to help identify and prevent this loss in sensitivity. In the final study we sought to use EEG-fMRI to characterize the relationship between the brain’s functional organization and Interictal Epileptiform Discharges (IEDs) in paediatric focal epilepsy. Interestingly, we identified increasing connectivity of the piriform cortex and caudate to the default mode network as a function of IEDs. This suggested a mechanism by which IEDs may propagate through functional networks in the brain.

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Ciumas, Carolina. "Multimethodological brain imaging studies of human epilepsy /." Stockholm, 2007. http://diss.kib.ki.se/2007/978-91-7357-268-2/.

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Vestal, Matthew Lepore. "Ictal Functional Neuroimaging of Childhood Absence Epilepsy." Yale University, 2010. http://ymtdl.med.yale.edu/theses/available/etd-05232010-232028/.

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Absence seizures in Childhood Absence Epilepsy (CAE) are 5 10 second episodes of impaired consciousness that are characterized on electroencephalography (EEG) by frontally-predominant, 3 4 Hz spike and wave discharges (SWD). The aims of this study were to use simultaneous EEG, functional magnetic resonance imaging (fMRI), and behavioral testing to identify the neural networks involved in absence seizures as well as to examine the timecourse of those ictal fMRI changes. It was hypothesized that absence seizures involve wide-reaching neural networks including the areas traditionally associated with normal attention processing and that absence seizures produce fMRI signal changes not only during the seizure, but before and after it as well. In this study, we recorded 88 absence seizures from a cohort of 42 children with pure CAE. These seizures were recorded as subjects participated in simultaneous EEG-fMRI scanning while engaged in a continuous performance task (CPT) of attentional vigilance or a repetitive tapping task (RTT) requiring repetitive motor activity. Using a novel, voxel-based percent fMRI change analysis combined with a volume of interest analysis, the second-by-second fMRI signal timecourse of the absence seizures were examined across numerous brain regions of interest, from 20 seconds before seizure onset through 40 seconds after seizure onset. EEG frequency analysis revealed seizures with a mean duration of 6.6 seconds and an abrupt onset and ending that were comprised of frontally-predominant, 3 4 Hz SWD. Ictal behavioral testing demonstrated abrupt onset of impairments during periods of SWD. These behavioral impairments were typical of CAE absence seizures in that impairments were greater in the CPT of attentional vigilance (omission error rate, OER = 81%) than in RTT testing (OER = 39 %) (p < 0.003). The ictal fMRI changes we observed varied depending upon the method of fMRI signal analysis used. Using the traditional general liner model, and assuming the standard hemodynamic response (HRF) function, this study replicated results consistent with previous ictal absence fMRI studies showing ictal activations primarily in the thalamus and ictal deactivations in traditional default mode areas. Using a more data-driven, novel voxel-based fMRI percentage change analysis to examine the ictal fMRI timecourse on a second-by-second basis, both ictally as well as pre- and post- ictally, this study, however, demonstrated ictal involvement of diverse brain regions before, during, and after the seizure. Activation was demonstrated up to 16 seconds before seizure onset, starting first in the parietal and orbital-medial frontal cortices and progressing to lateral frontal and lateral temporal cortices followed by the occipital and Rolandic cortices and finally the thalamus. Deactivation followed a similar anatomic progression and lasted up to 17 seconds after the end of SWD. These findings reveal a complex and long-lasting sequence of fMRI changes in CAE absence seizures that are not detectable by conventional HRF modeling and are important in the understanding and eventual treatment of absence seizures associated with CAE.

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Kreilkamp, Barbara A. K. "Advanced magnetic resonance imaging and quantitative analysis approaches in patients with refractory focal epilepsy." Thesis, University of Liverpool, 2017. http://livrepository.liverpool.ac.uk/3017303/.

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Background Epilepsy has a high prevalence of 1%, which makes it the most common serious neurological disorder. The most difficult to treat type of epilepsy is temporal lobe epilepsy (TLE) with its most commonly associated lesion being hippocampal sclerosis (HS). About 30-50% of all patients undergoing resective surgery of epileptogenic tissue continue to have seizures postoperatively. Indication for this type of surgery is only given when lesions are clearly visible on magnetic resonance images (MRI). About 30% of all patients with focal epilepsy do not show an underlying structural lesion upon qualitative neuroradiological MRI assessment (MRI-negative). Objectives The work presented in this thesis uses MRI data to quantitatively investigate structural differences between brains of patients with focal epilepsy and healthy controls using automated imaging preprocessing and analysis methods. Methods All patients studied in this thesis had electrophysiological evidence of focal epilepsy, and underwent routine clinical MRI prior to participation in this study. There were two datasets and both included a cohort of age-matched controls: (i) Patients with TLE and associated HS who later underwent selective amygdalahippocampectomy (cohort 1) and (ii) MRI-negative patients with medically refractory focal epilepsy (cohort 2). The participants received high- resolution routine clinical MRI as well as additional sequences for gray and white matter (GM/WM) structural imaging. A neuroradiologist reviewed all images prior to analysis. Hippocampal subfield volume and automated tractography analysis was performed in patients with TLE and HS and related to post-surgical outcomes, while images of MRI- negative patients were analyzed using voxel-based morphometry (VBM) and manual/automated tractography. All studies were designed to detect quantitative differences between patients and controls, except for the hippocampal subfield analysis as control data was not available and comparisons were limited to patients with persistent postoperative seizures and those without. Results 1. Automated hippocampal subfield analysis (cohort 1): The high-resolution hippocampal subfield segmentation technique cannot establish a link between hippocampal subfield volume loss and post-surgical outcome. Ipsilateral and contralateral hippocampal subfield volumes did not correlate with clinical variables such as duration of epilepsy and age of onset of epilepsy. 2. Automated WM diffusivity analysis (cohort 1): Along-the-tract analysis showed that ipsilateral tracts of patients with right/left TLE and HS were more extensively affected than contralateral tracts and the affected regions within tracts could be specified. The extent of hippocampal atrophy (HA) was not related to (i) the diffusion alterations of temporal lobe tracts or (ii) clinical characteristics of patients, whereas diffusion alterations of ipsilateral temporal lobe tracts were significantly related to age at onset of epilepsy, duration of epilepsy and epilepsy burden. Patients without any postoperative seizure symptoms (excellent outcomes) had more ipsilaterally distributed WM tract diffusion alterations than patients with persistent postoperative seizures (poorer outcomes), who were affected bilaterally. 3. Automated epileptogenic lesion detection (cohort 2): Comparison of individual patients against the controls revealed that focal cortical dysplasia (FCD) can be detected automatically using statistical thresholds. All sites of dysplasia reported at the start of the study were detected using this technique. Two additional sites in two different patients, which had previously escaped neuroradiological assessment, could be identified. When taking these statistical results into account during re-assessment of the dedicated epilepsy research MRI, the expert neuroradiologist was able to confirm these as lesions. 4. Manual and automated WM diffusion tensor imaging (DTI) analysis (cohort 2): The analysis of consistency across approaches revealed a moderate to good agreement between extracted tract shape, morphology and space and a strong correlation between diffusion values extracted with both methods. While whole-tract DTI-metrics determined using Automated Fiber Quantification (AFQ) revealed correlations with clinical variables such as age of onset and duration of epilepsy, these correlations were not found using the manual technique. The manual approach revealed more differences than AFQ in group comparisons of whole-tract DTI-metrics. Along-the-tract analysis provided within AFQ gave a more detailed description of localized diffusivity changes along tracts, which correlated with clinical variables such as age of onset and epilepsy duration. Conclusions While hippocampal subfield volume loss in patients with TLE and HS was not related with any clinical variables or to post-surgical outcomes, WM tract diffusion alterations were more bilaterally distributed in patients with persistent postoperative seizures, compared to patients with excellent outcomes. This may indicate that HS as an initial precipitating injury is not affected by clinical features of the disorder and automated hippocampal subfield mapping based on MRI is not sufficient to stratify patients according to outcome. Presence of persisting seizures may depend on other pathological processes such as seizure propagation through WM tracts and WM integrity. Automated and time-efficient three-dimensional voxel-based analysis may complement conventional visual assessments in patients with MRI-negative focal epilepsy and help to identify FCDs escaping routine neuroradiological assessment. Furthermore, automated along-the-tract analysis may identify widespread abnormal diffusivity and correlations between WM integrity loss and clinical variables in patients with MRI-negative epilepsy. However, automated WM tract analysis may differ from results obtained with manual methods and therefore caution should be exercised when using automated techniques.

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Webb, Jocasta Anne. "Magnetic resonance image analysis techniques for quantification of hippocampal integrity in temporal lobe epilepsy." Thesis, University of Liverpool, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367210.

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Li, Xiao, and 李瀟. "Feasibility of T1rho imaging in lateralization of the epileptogenic zones in patients with mesial temporal lobe epilepsy : comparisons with MR volumetry and T2 relaxometry." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/197080.

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Underling neuronal loss and subsequent hippocampal sclerosis, as reflected by hippocampal atrophy on structural magnetic resonance (MR) imaging, are the dominant findings in the patient with mesial temporal lobe epilepsy (MTLE). Yet, prolongation of T2 relaxation time has also been reported as an early marker for MTLE, but it is a rather insensitive marker. Typical age-related atrophy often constitutes a significant confounding factor, and atrophy often represents a late sign in hippocampal sclerosis. In this connection, there is an urge for a sensitive independent predictor for the early detection of MTLE. T1rho MR imaging provides a distinct contrast mechanism in tissue characteristics. It is sensitive to physio-chemical processes and has been tested successfully in Alzheimer’s disease, Parkinson’s disease and certain brain tumors. Therefore, it is possible to depict early biochemical change in patients with MTLE by means of measuring the changes in T1rho relaxation time. T1rho relaxation time is not affected by age-related atrophic changes and thus can be used as an independent marker. In this preliminary study, we aimed to assess the feasibility of T2 relaxometry and T1rho MR imaging in identification of the atrophied zones in patients with MTLE. Seven patients with unilateral MTLE and fourteen normal subjects were recruited. Three-dimensional T1-weighted imaging, axial T2 relaxometry and T1rho imaging were performed on a 3T MR scanner. Hippocampal head, hippocampal body, hippocampal tail and amygdala were contoured on the axial T2-weighted images and then co-registered onto T2 relaxometry and T1rho images. A combination of visual and quantitative volumetric assessment was used as the primary end outcome. For T2 relaxometry and T1rho imaging, their respective relaxation times together with the corresponding right-left asymmetric ratios were calculated for subsequent analysis. Abnormal right-left asymmetric ratio is defined as a deviation of 2SD from the mean of the Z-score. In the lateralizing epileptogenic zones, T1rho yielded an overall accuracy of 92.9% (sensitivity 100%, specificity 60%), while T2 relaxometry yielded an overall accuracy of 71.4% (sensitivity 65.2%, specificity 100%) only. T1rho imaging is thus superior to T2 relaxometry (P = 0.036, by chi-square test). To conclude, the present study indicated that T1rho is feasible and potentially useful to serve as a non-invasive imaging tool in the detection of lateralization of the epileptogenic zone in patients with MTLE. It can also facilitate prompt diagnosis and longitudinal disease monitoring. In addition, the generation of associated color-coded parametric map can provide an easy mean for direct visual analysis.
published_or_final_version
Diagnostic Radiology
Master
Master of Philosophy

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Collin, Greize 1983. "Estudo da associação entre atrofia de estruturas limbicas, depressão e epilepsia de lobo temporal mesial." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/309283.

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Orientador: Fernando Cendes
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas
Made available in DSpace on 2018-08-19T22:39:04Z (GMT). No. of bitstreams: 1 Collin_Greize_M.pdf: 5813301 bytes, checksum: cca632f33b2c0f7db3ef862ea7b00df4 (MD5) Previous issue date: 2012
Resumo: A depressão tem sido um dos transtornos mentais mais comumente relatados em associação com ELTM, com uma prevalência estimada de 20 a 55%, contra 9% na população em geral, e os aspectos que interagem na associação das epilepsias e da depressão são ainda hoje muito fragmentados, fazendo com que a fisiopatologia da depressão nas epilepsias ainda não esteja inteiramente esclarecida. Sendo assim, o objetivo deste trabalhou foi investigar a associação das alterações volumétricas das amígdalas, hipocampos e tálamos em pacientes com ELTM e depressão, e também correlacionar os dados volumétricos obtidos com os dados clínicos de cada paciente, como frequência de crises e intensidade de sintomas depressivos mensurados através do BDI. Para isso, foram adquiridas imagens de RM em 4 grupos de 20 indivíduos cada: Grupo ED: pacientes com ELTM e depressão; Grupo E: pacientes com ELTM; Grupo D: pacientes com depressão e o Grupo C: controles saudáveis. A segmentação das Amígdalas, Hipocampos e Tálamos foram realizadas através do software DISPLAY, de acordo com protocolos específicos para cada estrutura. Também avaliamos o Índice de Assimetria (IA), que é a razão entre o volume do menor/maior lado apresentado por cada estrutura. O diagnóstico para o transtorno depressivo foi realizado através de avaliação neuropsicológica de acordo com os critérios do DSM-IV aplicando a SCID-I. O Inventário para Depressão de Beck (BDI) foi utilizado para mensurar a intensidade dos sintomas depressivos. Para a análise estatística, foi utilizado o programa SYSTAT 9®, com os testes de ANOVA, Teste-t de Student e correlação de Spearman. Foram incluídas neste estudo 80 mulheres com idade média ± desvio padrão 40±9,4 anos. Comparamos as médias dos volumes absolutos corrigidos da AD (t=5,552, p=0,002) e AE (t=14,571, p<0,0001) entre os grupos, e observamos que os grupos C e E apresentaram diferença significativa em relação à AD (p=0,004) e AE (p<0,0001). Já nos grupos D e E, houve diferença significativa apenas na AE (p<0,0001). Nos grupos E e ED, encontramos diferença significativa em relação a AD (p=0,004) e AE (p<0,0001). Não houve diferença significativa em relação à média dos volumes corrigidos do HD (F= 0,461, p=0,711) e HE (F=2,329, p=0,081) e dos TD (F=0,786, p=0,505) e TE (F=0,492, p=0,689) entre os grupos. Em relação aos IAH (t=9,793, p<0,0001), somente os grupos C e E (p=0,001), C e ED (p=0,001), D e E (p=0,004) e D e ED (p=0,003) revelaram assimetria significativa. Em relação ao IAT (t=2,483, p=0,067) encontramos assimetria significativa somente entre os grupos E e ED (p=0,039). Não houve diferença significativa referente ao IAA entre os grupos. Observamos correlação positiva entre frequência de crises e escore do BDI (rs=0,481), em que a média da frequência mensal de crises foi maior para o grupo com ELTM associada à depressão (7,45±8,28) do que para o grupo somente com ELTM (3,05±2,85), havendo uma diferença significativa entre os grupos (t=-2,245, p=0,031). Nós concluímos que não houve relação significativa entre o grau de atrofia das estruturas límbicas e a presença de transtorno de humor em pacientes com ELTM. Entretanto, nossos resultados indicaram que a frequência de crises está relacionada à gravidade dos sintomas depressivos nos pacientes com ELTM
Abstract: Depression has been one of the most commonly related mental disorders associated with MTLE, reaching approximately 20% to 55% of the cases, whereas its prevalence is 9% in the general population. Since the aspects that interact in the association MTLE-depression are still quite fragmented, the physiopathology of depression in MTLE is not fully understood. This study has the aim of investigating the association of volumetric differences of amygdala, hippocampus and thalamus in MTLE and depressed patients, as well as correlating these with each patient's clinical data (such as seizure frequency and intensity of depressive symptoms). Magnetic Resonance images were acquired in 4 groups of 20 patients each: group ED - patients with MTLE and depression; group E - patients with MTLE; group D - patients with depression; and group C - healthy controls. The segmentation of amygdala, hippocampus and thalamus was performed using DISPLAY software, according to protocols validated by our group. We evaluated the asymmetry index (AI), which represents the ratio between the smallest and the largest side of each structure. The diagnosis for depressive disorder was performed in accordance with DSM-IV criteria obtained through the SCID-I applied by a trained professional. To measure the intensity of depressive symptoms we used Beck Depression Inventory (BDI), and SYSTAT 9®, ANOVA, Student's t-test and Spearman correlation for statistical analysis. 80 women with mean age of 40 years (SD=9.4) were analyzed. We compared the mean absolute volumes of RA (t=5.552, p=0.002) and LA (t=14.571, p<0.0001) between groups, and observed there was a significant difference between groups C and E related to RA (p=0.004) and LA (p<0.0001). Regarding groups D and E, there was a significant difference only in AE (p<0.0001), and groups E and ED in AD (p=0.004) and AE (p<0.0001). There was neither significant difference between RH (F= 0.461, p=0.711) and LH (F=2.329, p=0.081) mean volumes nor RT (F=0.786, p=0.505) and LT (F=0.492, p=0.689) between groups. In relation to HAI (t=9.793, p<0.0001), only the groups C and E (p=0.001), C and ED (p=0.001), D and E (p=0.004) and D and ED (p=0.003) presented a significant asymmetry. Concerning TAI (t=2.483, p=0.067), we found significant difference only between groups E and ED (p=0.039) and we did not find difference of AAI between any groups. We observed a positive correlation between BDI scores and seizure frequency (rs=0.481), in which the average monthly seizure frequency was higher (t=-2.245, p=0.031) for the ED group (7.45±2.85) than E group (3.05±2.85). It is concluded that there was no significant relationship between the degree of atrophy of limbic structures and the presence of mood disorder in patients with MTLE. However, our results indicate that seizure frequency is related to severity of depressive symptoms in patients with MTLE
Mestrado
Fisiopatologia Médica
Mestre em Ciências

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Horwood, Linda. "The magnetic resonance imaging-based assessment of whole-brain structural integrity in temporal lobe epilepsy." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=21935.

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In temporal lobe epilepsy (TLE), the most common pathological finding ipsilateral to the seizure focus is sclerosis of the hippocampus. Magnetic resonance imaging (MRI) allows the in vivo assessment of brain abnormalities in TLE patients. This thesis presents the application of advanced MRI post-processing techniques in a cross-sectional study of TLE patients and healthy controls, exploring the pattern of atrophy in TLE. Methods include the automatic segmentation of lobar grey and white matter and limbic (cingulate, thalamus, and insula) structures and the manual segmentation of mesial temporal lobe structures (hippocampus, amygdala and entorhinal cortex). Results of quantitative imaging are evaluated with respect to clinical parameters (disease duration, history of febrile convulsions, generalized tonic-clonic seizures, postoperative outcome). The findings demonstrate volume losses both proximal and distal to the seizure focus, particularly implicating limbic structures. The results also indicate negative effects of hippocampal atrophy and a left-sided focus on brain structural integrity in TLE.
Dans l'épilepsie du lobe temporal (ELT), la lésion la plus commune est une sclérose de l'hippocampe ipsilatérale au foyer épileptique. L'imagerie par résonance magnétique (IRM) permet l'évaluation in vivo des anomalies dans le cerveau des patients. Cette thèse présente l'application des techniques avancées de traitement d'image dans une étude transversale entre des patients atteints d'ELT et des sujets sains, explorant la distribution de l'atrophie cérébrale dans l'ELT. Les méthodes incluent la segmentation automatique de la matière grise et blanche par lobe et des structures limbiques (cortex cingulaire, thalamus et insula), et la segmentation manuelle des structures mésiales du lobe temporal (hippocampe, amygdale et cortex entorhinale). Les résultats de l'IRM quantitative sont évalués en relation avec des paramètres cliniques (durée de la maladie, histoire des convulsions fébriles, crises tonique-cloniques généralisées, résultats postopératoires). Les résultats démontrent des réductions de volume à proximité et à distance du foyer épileptique, incluant notamment les structures limbiques. Les résultats indiquent également un effet négatif lié à l'atrophie de l'hippocampe et un foyer épileptique dans l'hémisphère gauche sur l'intégrité structurale du cerveau dans l'ELT.

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LeVan, Pierre. "Independent component analysis of simultaneously acquired electroencephalography and functional magnetic resonance imaging in focal epilepsy patients." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=86790.

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Simultaneous electroencephalography and functional magnetic resonance imaging (EEG-fMRI) is a potentially useful diagnostic modality for the presurgical evaluation of patients with refractory focal epilepsy. The goal of EEG-fMRI is to localize hemodynamic correlates of epileptic discharges. The data is usually analyzed in the general linear model (GLM) framework, which assumes that the electrical and hemodynamic signals are coupled by a fixed canonical hemodynamic response function (HRF). However, the HRF is known to show some variability that may affect the sensitivity of the method. Investigating this variability may reveal additional useful information about the data.
This thesis presents a method to analyze EEG-fMRI data independently of a prior HRF model, using independent component analysis (ICA). With minimal prior assumptions, ICA can decompose the fMRI into components representing the major fluctuations present in the data. A deconvolution method then identifies components showing significant signal changes related to the epileptic discharges, independently of the HRF shape.
First, the performance of the proposed method is evaluated on simulated activations under a wide variety of realistic conditions. It is also shown that the GLM framework may fail to detect activations if the HRF varies only slightly from the canonical shape. The method is then applied to recordings of epileptic seizures. The GLM analysis typically yields very widespread areas of activation, but the ICA method can decompose these areas into multiple clusters with various HRF peak delays. Clusters with early HRF delays correspond well with presumed seizure onset regions, while other clusters may be related to seizure propagation. Finally, the method is used to investigate the variability of the HRF amplitude in response to interictal epileptiform discharges (IED). It is shown that clusters of activation in the presumed epileptogenic focus show a significant correlation between HRF amplitudes and IED amplitudes, unlike clusters in distant regions. Therefore, the method can improve the specificity of the EEG-fMRI analysis.
L'enregistrement simultané de l'électroencéphalogramme et de l'imagerie par résonance magnétique fonctionnelle (EEG-IRMf) constitue une modalité potentiellement utile pour l'évaluation préchirurgicale de patients souffrant d'épilepsie focale réfractaire. L'objectif de l'EEG-IRMf est de localiser les corrélats hémodynamiques de décharges épileptiques. Les données sont habituellement analysées dans le cadre du modèle linéaire généralisé (MLG), qui définit la relation entre les signaux électriques et hémodynamiques par une fonction de réponse hémodynamique (FRH) canonique fixe. Cependant, la FRH démontre une certaine variabilité pouvant affecter la sensibilité de la méthode. L'examen de cette variabilité pourrait révéler des informations additionnelles au sujet des données.
Cette thèse présente une méthode d'analyse des données EEG-IRMf indépendamment d'un modèle de la FRH, basée sur l'analyse en composantes indépendantes (ACI). Avec un minimum de présuppositions, l'ACI peut décomposer l'IRMf en composantes représentant les fluctuations majeures présentes dans les données. Ensuite, une déconvolution identifie les composantes ayant une variation significative de signal reliée aux décharges épileptiques, indépendamment de la forme de la FRH.
La performance de la méthode proposée est d'abord évaluée sur des activations simulées sous diverses conditions réalistes. Il est également démontré que le MLG risque de ne pas détecter d'activations si la FRH est légèrement différente de la forme canonique. La méthode est ensuite appliquée à des enregistrements de crises épileptiques. Typiquement, l'analyse par le MLG génère de larges régions activées, mais la méthode basée sur l'ACI peut décomposer ces régions en plusieurs groupes ayant divers délais de la FRH. Les régions ayant un délai précoce de la FRH correspondent bien avec la zone présumée d'origine des crises, alors que les autres régions pourraient être reliées à la propagation des crises. Enfin, la méthode est utilisée pour étudier la variabilité de l'amplitude de la FRH en relation avec des décharges épileptiformes interictales (DEI). Il est démontré que les régions d'activation dans la zone épileptogène présumée montrent une corrélation significative entre les amplitudes des FRHs et des DEIs, ce qui n'est pas le cas pour les régions plus distantes. La méthode peut donc améliorer la spécificité de l'analyse des données EEG-IRMf.

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13

Beltramini, Guilherme Côco 1985. "Análise temporal de correlatos hemodinâmicos associados à atividade epileptiforme através da técnica de EEG-RMf simultâneos." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/276970.

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Orientador: Roberto José Maria Covolan
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin
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Resumo: Epilepsia é uma doença neurológica que afeta pessoas no mundo todo, atingindo em torno de 1% da população mundial. Aproximadamente 30% dos pacientes não respondem bem ao tratamento com medicamentos. A abordagem cirúrgica é uma alternativa recomendada somente quando se localiza, de forma precisa, a região epileptogênica, razão pela qual os pacientes são submetidos a diversas avaliações invasivas e não-invasivas, incluindo exames de neuroimagem estrutural e funcional. A técnica de EEG-RMf simultâneos surgiu da combinação do EEG, de uso consagrado em pacientes com epilepsia, com a RMf, procedimento cada vez mais aplicado em estudos funcionais do cérebro, tendo sido encarada desde sua concepção inicial com a perspectiva de se constituir em um novo exame não invasivo na avaliação pré-cirúrgica em epilepsia. As dificuldades instrumentais inerentes a esta técnica têm sido superadas mais rapidamente do que o desenvolvimento de métodos empregados na análise e interpretação dos resultados gerados através dela. Isto ocorre em parte devido à complexidade e diversidade de causas da epilepsia, que afeta o cérebro do ponto de vista estrutural e funcional, podendo atingi-lo desde o âmbito genético até níveis macroscópicos. Neste trabalho, estabelecemos uma sequência de procedimentos para a aquisição e análise de dados de EEG-RMf, possibilitando o uso deste exame como uma informação adicional na avaliação pré-cirúrgica. Criamos um programa de computador chamado SAfE (Straightforward Analysis of fMRI and EEG-fMRI), que permite realizar as análises de experimentos de EEG-RMf de forma direta e segura. Após aplicar as correções no sinal do EEG e realizar a marcação da atividade epileptiforme, mapas estatísticos de RMf podem ser obtidos através de uma interface gráfica simples, com pouca intervenção do usuário. Para observar simultaneamente os aspectos temporais e espaciais das alterações hemodinâmicas relacionadas com os diferentes tipos de atividade epileptiforme de cada paciente, foi proposta e incorporada ao SAfE uma forma original de se descrever os resultados. São gerados mapas estatísticos para diferentes posições do pico da função resposta hemodinâmica, que são então analisados sequencialmente, observando-se diferentes parâmetros, tais como o valor de T máximo e número de voxels acima do limiar. A abordagem aqui proposta para a análise dos dados de EEG-RMf sugere que os mapas estatísticos dos pacientes sejam examinados preferencialmente de forma individual, pois parte importante da informação pode ser perdida quando se combinam os resultados em análises de grupo. Os resultados obtidos revelam a alta complexidade dos mecanismos geradores de atividade epileptiforme, pois as redes cerebrais envolvidas mostram um elevado grau de heterogeneidade entre os pacientes e entre os diferentes tipos de atividade epileptiforme considerados. Possivelmente sistemas locais e remotos interagem de forma a causar alterações crônicas que afetam a propagação da crise e da atividade epileptiforme. A técnica de EEG-RMf tem se mostrado uma aplicação com valor clínico promissor, porém requer validação através da comparação com procedimentos mais bem estabelecidos. Embora os benefícios desta técnica sejam limitados em pacientes com atividade epileptiforme de difícil detecção, entende-se que seu desenvolvimento deverá contribuir para tornar mais robusta a avaliação pré-cirúrgica realizada atualmente
Abstract: Epilepsy is a neurological disease that affects people worldwide, reaching about 1% of the world population. Approximately 30% of the patients do not respond well to treatment with medication. The surgical approach is an alternative recommended only when the epileptogenic region can be precisely localized. For this reason patients are subjected to various invasive and non-invasive assessments, including structural and functional neuroimaging exams. Simultaneous EEG-fMRI recordings originated from the combination of EEG, which has traditional use in epilepsy patients, with fMRI, a procedure increasingly applied to functional studies of the brain. This technique has been treated since its conception as a potential new non-invasive exam in the presurgical evaluation in epilepsy. Its inherent instrumental difficulties have been overcome more rapidly than the development of methods employed in the analysis and interpretation of the results. This is partly due to the complexity and diversity of causes of epilepsy, which affects the brain from the structural and functional standpoints, possibly disturbing it from genetic to macroscopic levels. In this work, we established a sequence of procedures for the acquisition and data analysis of EEG-fMRI, enabling the use of this technique as an additional exam in the presurgical evaluation. We created a computer program called SAfE (Straightforward Analysis of fMRI and EEG-fMRI), which allows straightforward and safe EEG-fMRI data analysis. After performing the EEG signal correction and identifying the epileptiform activity, fMRI statistical maps can be obtained through a simple graphical interface with little user input. An original form of describing the results was proposed and integrated in SAfE, in order to simultaneously examine the temporal and spatial aspects of the hemodynamic changes associated with the different types of epileptiform activity of each patient. Statistical maps are generated for different peak positions of the hemodynamic response and are then sequentially analyzed considering different parameters such as the maximum T value and the number of voxels above threshold. The approach proposed here for the EEG-fMRI data analysis suggests that the statistical maps of the patients should preferably be examined individually, because important information can be lost when the results are combined in group analyses. The obtained results reveal the high complexity of the mechanisms that generate epileptiform activity, because the brain networks involved show an elevated degree of heterogeneity among patients and among the different types of epileptiform activity. Possibly local and remote systems interact in such a way to cause chronic changes that affect the spread of the seizure and epileptiform activity. The EEG-fMRI technique has shown to be an application with promising clinical value, but requires validation via comparison with more established procedures. Although the benefits of this technique are limited in patients whose epileptiform activity is difficult to detect, its development is expected to make the current presurgical evaluation more robust
Doutorado
Física
Doutor em Ciências

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14

Adcock, Jane Elizabeth St Vincent's Clinical School UNSW. "The reliability and clinical validity of functional magnetic resonance imaging in the assessment of language in pre-surgical patients with temporal lobe epilepsy." Awarded by:University of New South Wales. St Vincent's Clinical School, 2005. http://handle.unsw.edu.au/1959.4/22484.

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Defining language lateralisation is important to minimise morbidity in patients treated surgically for temporal lobe epilepsy (TLE). Functional magnetic resonance imaging (fMRI) offers a promising, non-invasive, alternative strategy to the Wada test. Here, fMRI has been used to study healthy controls and patients with TLE in order (i) to define language-related activation patterns and their reproducibility; (ii) to compare lateralisation determined by fMRI with that from the Wada test; and (iii) to explore the usefulness of multiple fMRI language paradigms. 18 healthy controls (12 right-handed and 6 left-handed) and 24 pre-operative TLE patients (19 right-handed: 12 left-TLE, 7 right-TLE; 5 left-handed: 2 right-TLE, 3 left-TLE) were studied using fMRI. Four fMRI language paradigms used: phonetic and semantic fluency, and the naming of living and non-living things. The data for all 4 tasks were acquired during a single scanning session on two occasions. All patients also underwent Wada testing. In patients and controls, phonetic and semantic fluency tasks were robustly activating and strongly lateralising. Quantified language-related lateralisation from fMRI verbal fluency data was highly reproducible and concordant with the lateralisation of the Wada test. Both fluency tasks identified patients with atypical language lateralisation, including 4/12 right-handed patients with left-TLE and 4/5 left-handed TLE patients, regardless of the side of epileptic focus. In comparison, the two confrontational naming tasks were not strongly lateralising and did not reliably agree with Wada lateralisation in either 12 right-handed controls or 19 right-handed patients with TLE. However, there was a difference in the pattern of fMRI activation in right-handed pat ients with left-TLE. Left-TLE patients had a more right lateralised network of activation when naming living things relative to non-living things, suggesting that some patients may be at risk of a category specific naming decline for non-living things after left anterior temporal lobectomy. These results demonstrate that non-invasive fMRI measures of languagerelated lateralisation may provide a practical and reliable alternative to invasive testing for pre-surgical language lateralisation in patients with TLE. The high proportion of TLE patients showing atypical language lateralisation suggests considerable plasticity of language representation in the brains of patients with intractable TLE.

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15

Lundberg, Staffan. "Rolandic Epilepsy : A Neuroradiological, Neuropsychological and Oromotor Study." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4133.

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16

Maynard, Lauren M. "Predictors of Epilepsy Severity in MRI-Identified Focal Cortical Dysplasia." University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1458299543.

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17

Betting, Luiz Eduardo Gomes Garcia. "Epilepsia generalizada idiopatica : aspectos etnicos, eletroencefalograficos e de neuroimagem l." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/309309.

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Orientadores: Fernando Cendes, Li Li Min
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas
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Resumo: Epilepsias generalizadas idiopáticas (EGI) constituem de 20-40% das epilepsias e de forma oposta às epilepsias parciais, anormalidades estruturais não são esperadas. De acordo com a idade de início e o tipo principal de crise, as EGI são divididas principalmente em epilepsia ausência infantil e juvenil (EA), epilepsia mioclônica juvenil (EMJ) e epilepsia com crises tônico-clônicas generalizadas (CTCG). Os limites entre estas subsíndromes são imprecisos e a classificação muitas vezes é difícil. Devido às características semelhantes, alguns autores consideram a EGI como uma única patologia com múltiplos fenótipos (continuum biológico). O eletroencefalograma (EEG) auxilia no diagnóstico das EGI especialmente quando evidencia descargas do tipo espícula onda-lenta generalizadas com atividade de base normal. Entretanto, o EEG pode ser normal e até mesmo mostrar focalidades dificultando o diagnóstico. A ressonância magnética (RM) não é realizada de forma rotineira em pacientes com EGI. Contudo, novas técnicas de aquisição e processamento de imagens vêm detectando anormalidades sutis nestes indivíduos. O objetivo deste estudo foi investigar a fisiopatologia das EGI através da análise de características clínicas, eletroencefalográficas e de neuroimagem. Inicialmente, as características dos EEGs de 180 pacientes com diagnóstico clínico de EGI foram avaliadas. 493 exames foram analisados. Em 33% dos pacientes o EEG inicial foi característico e em 22% o exame evidenciou focalidades. Após a identificação de focalidades utilizamos a neuroimagem convencional (análise visual) na avaliação de 134 pacientes com EGI. Observamos anormalidades na RM de 27 (20%) pacientes. A maioria das anormalidades não apresentou relação direta com as crises. Utilizamos a técnica da morfometria baseada em voxel (MBV) para investigar lesões discretas eventualmente não identificadas na neuroimagem de rotina. Esta técnica permite a comparação entre grupos de imagens aumentando a chance de detecção de anormalidades. Observamos aumento na concentração de substância cinzenta (CSC) localizada no córtex frontal de pacientes com EMJ (n=44) e EA (n=24). Observamos também uma maior CSC na região anterior do tálamo nos pacientes com crises de ausência (n=47). Avaliando as focalidades clínicas e de EEG de 22 pacientes com EGI utilizando a MBV, observamos áreas de aumento da CSC em 8 dos 9 (89%) pacientes com EMJ, 5 dos 6 (83%) pacientes com EA e 5 dos 7 (71%) pacientes com CTCG ao despertar. A volumetria do tálamo foi realizada para investigar o aumento de CSC sugerido pela MBV. A comparação entre 147 pacientes e um grupo controle evidenciou um maior volume da região anterior do tálamo nos pacientes com crises de ausência. Nossos resultados revelam que a fisiopatologia das EGI envolve o tálamo e o córtex cerebral. As diversas alterações na neuroimagem quantitativa apresentadas por cada subsíndrome sugerem um diferente mecanismo para as EGI. Este achado fortalece o conceito de diferentes doenças com fenótipos semelhantes. Mais do que isso, nossos achados indicam, uma alteração estrutural no cérebro destes indivíduos. Os diversos fenótipos estão relacionados a diferentes mecanismos fisiopatológicos. As focalidades observadas no EEG e na RM refletem a patogênese das crises em pacientes com EGI
Abstract: Idiopathic generalized epilepsies (IGE) represent 20-40% of all epilepsies and opposed to partial epilepsies, structural abnormalities are not expected. According to the age of onset and the main seizure type, IGE are divided mainly in childhood and juvenile absence epilepsy (AE), juvenile myoclonic epilepsy (JME) and generalized tonic-clonic seizures (GTCS). The limits between these subsyndromes are unclear and sometimes classification is difficult. Because of the similar characteristics, some authors consider IGE as a single pathology with multiple phenotypes (biological continuum). Electroencephalogram (EEG) helps the IGE diagnosis specially when it shows the generalized spike and wave discharges with normal background. However, the EEG may be normal or even disclose focalities difficulting the diagnosis. Magnetic resonance imaging (MRI) is not routinely performed in patients with IGE. In spite of this, new techniques of acquisition and processing of the images are detecting subtle abnormalities in these individuals. The objective of this study was to investigate the pathophysiology of the IGE using the clinical, EEG and neuroimaging features. Initially, the characteristics of the EEGs of 180 patients with clinical diagnosis of IGE were evaluated. 493 exams were analyzed. In 33% of the patients the initial EEG was characteristic and in 22% the exam revealed focalities. After the identification of the focalities, we used conventional neuroimaging (visual analysis) on the evaluation of 134 patients with IGE. We observed abnormalities in the MRI of 27 (20%) patients. Most of the abnormalities were not directly related to the seizures. We used the voxel base morphometry (VBM) technique to evaluate the images. This technique allows comparisons between groups of images increasing the chances of detecting abnormalities. We observed increased gray matter concentration (GMC) localized in the frontal cortex of patients with JME (n=44) and AE (n=24). We also observed increased GMC in the anterior thalamic region of patients with absence seizures (n=47). Evaluating the clinical and EEG focalities of 22 patients with IGE using VBM, we observed areas of increased GMC in 8 of 9 (89%) patients with JME, 5 of 6 (83%) patients with AE and 5 of 7 (71%) patients with GTCS on awakening. The volumetry of the thalamus was performed to investigate the increased GMC suggested by the VBM. The comparison between 147 patients with a control group showed increased volume of the anterior thalamic region in patients with absence seizures. Our results revealed that the pathophysiology of the IGE involves the thalamus and the cerebral cortex. The several abnormalities on the neuroimage presented by each subsyndrome suggest a different mechanism for the IGE. This finding strengths the concept of multiple diseases with similar phenotypes. Furthermore, our findings indicate a structural abnormality in the brain of these individuals. The several phenotypes are related with different pathophysiological mechanisms. The focalities present on the EEG and in the MRI reflect the pathogenesis of the seizures in patients with IGE
Doutorado
Neurociencias
Doutor em Fisiopatologia Medica

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18

Campos, Brunno Machado de 1988. "Análise da resposta hemodinâmica em pacientes com epilepsia de lobo temporal mesial através do uso simultâneo de eletroencefalografia e ressonância magnética funcional." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/309279.

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Orientador: Fernando Cendes
Dissertação (Mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas
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Resumo: Introdução: A técnica multimodal de eletroencefalografia (EEG) acoplada à ressonância magnética (RM) funcional (RMf) apresenta características físicas complementares. Este método permite não só avaliar atividades neurais fisiológicas, mas também a dinâmica de neuropatologias como a epilepsia. Dentro do grupo das epilepsias, as epilepsias de lobo temporal (ELT) são particularmente importantes pela sua elevada prevalência e morbidade. Objetivo: Investigar e comparar os padrões de alterações hemodinâmicas associados a descargas epilépticas interictais (DEIs) em pacientes com ELT com (ELT-EH) ou sem (ELT-NL) sinais de esclerose hipocampal em exames de RM, através do uso combinado das técnicas de EEG e RMf (EEG-RMf). Métodos: Foram submetidos a exames de EEG-RMf, 25 pacientes com diagnóstico de ELT, sendo 12 ELT-NL e 13 ELT-EH. As imagens de RM foram adquiridas em aparelho de 3T e o EEG amostrado com 64 eletrodos compatíveis com RM. O tempo das DEIs foi utilizado para avaliar as respostas BOLD positivas (BOLDpos) e negativas (BOLDneg). Foram realizadas análises de EEG-RMf individuais e para grupos, além de análise estrutural, com o software SPM8-VBM8. As análises funcionais foram realizadas com pico da função resposta hemodinâmicas (FRH) em 0 segundo (precoce) e 5 segundos (tardio) após as DEIs. Resultados: Os mapas BOLDpos no grupo ELT-EH mostraram alterações hemodinâmicas precoces no lobo temporal ipsilateral, ínsula e giro precentral contralateral, e tardia no putâmem ipsilateral, cíngulo anterior bilateral, ínsula e lobos temporais. No grupo ELT-NL, BOLDpos precoce difuso foi observado, com alterações mais significativas no giro medial frontais ipsilateral, enquanto BOLDpos tardio foi observado na ínsula ipsilateral e giro temporal superior. Em ambos os grupos a análise estrutural mostrou redução significativa de substância cinzenta em áreas que se estendem além do lobo temporal, porém sem sobreposição significativa com áreas de BOLDpos. Em ambos os grupos de pacientes, BOLDneg foi observado em áreas compatíveis com default mode network (DMN). Interpretação: As redes funcionais relacionadas às DEIs diferem entre ELT-EH e ELT-NL. As regiões com atrofia mais significativa de substância cinzenta não coincidem com estas redes funcionais. Há possível supressão da atividade em áreas da DMN relacionadas com as DEIs em pacientes com ELT com ou sem sinais de EH
Abstract: Introduction: The multimodal technique of electroencephalography (EEG) coupled to functional magnetic resonance imaging (fMRI) presents additional physical characteristics. This method allows not only evaluating physiological neural activities, but also the dynamics of neuropathologies as epilepsy. Within the group of epilepsy, temporal lobe epilepsy (TLE) is particularly important due to its high prevalence and morbidity. Objective: To investigate and compare the patterns of hemodynamic changes associated with interictal epileptiform discharges (IEDs) in patients with TLE with (TLE-HS) or without (TLE-NL) signs of hippocampal sclerosis in MRI, through the combined use of EEG and fMRI techniques (EEG-fMRI). Methods: Twenty five patients diagnosed with TLE underwent EEG-fMRI scans, 12 with TLE-NL and 13 TLE-HS. MR images were acquired on a 3T scanner and EEG recorded with 64 electrodes compatible with MRI. The time for IED was used to assess the BOLD positive (BOLDpos) and negative (BOLDneg) responses. Analysis of EEG-fMRI MRI structural analyses were performed with SPM8-VBM8 software. The functional analyses were performed with the peak of the hemodynamic response function (HRF) in 0 second (early) and 5 seconds (late) after IED. Results: The BOLDpos maps in TLE-HS group showed early hemodynamic changes in ipsilateral temporal lobe, contralateral insula and precentral gyrus and late hemodynamic changes in ipsilateral putamen, bilateral anterior cingulate, insula and temporal lobes. In TLE-NL, diffuse early BOLDpos was observed, with the most significant changes in the ipsilateral medial frontal gyrus, while late BOLDpos was observed in the ipsilateral insula and superior temporal gyrus. In both groups the structural analysis showed significant reduction of gray matter in areas that extend beyond the temporal lobe, but with no significant overlap with areas of BOLDpos. In both groups of patients BOLDneg was observed in areas consistent with default mode network (DMN). Interpretation: The functional networks related to the IED differ in TLE-HS and TLE-NL. The regions with the most significant gray matter atrophy do not coincide with these functional networks. There is possible suppression of activity in the DMN areas related to IED in TLE patients with or without signs of HS
Mestrado
Fisiopatologia Médica
Mestre em Ciências

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19

Shibata, Sumiya. "Magnetoencephalography with temporal spread imaging to visualize propagation of epileptic activity." Kyoto University, 2017. http://hdl.handle.net/2433/226764.

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20

Monnerat, Bruno Zanotelli. "Convergência da videoeletroencefalografia prolongada e da ressonância magnética de encéfalo na determinação de zonas epileptogênicas extrahipocampais presumidas." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/17/17140/tde-05012017-092914/.

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Pacientes com epilepsia farmacorresistente, frequentemente, possuem lesões extrahipocampais como etiologia. Muitas vezes, estes pacientes se beneficiam de lesionectomias para redução da ocorrência de crises epilépticas. Para que possam se submeter a este procedimento, atualmente é necessário o uso tanto da videoeletroencefalografia prolongada (VEEG) quanto da imagem de ressonância magnética do encéfalo (IRM) para delimitação apurada da zona epileptogênica, local que deve ser ressecado para controle das crises. No presente trabalho, foi estudada a acurácia diagnóstica da VEEG e da IRM na determinação da zona epileptogênica de pacientes com displasia cortical focal. Comparou-se os locais de ocorrência da zona de início ictal (VEEG) e da lesão epileptogênica (IRM) se concordantes ou discordantes com o local da cirurgia. Foram revisados os prontuários médicos de 209 pacientes, sendo o padrão de referência (local da cirurgia) e tempo de acompanhamento pós-operatório superior a 12 meses disponíveis em 43 pacientes. A VEEG apresentou sensibilidade de 85,7% (IC 95% 62,6-96,2) e especificidade de 41,1% (IC 95% 19,4-66,5), com valor preditivo positivo de 64,2% (IC 95% 44,1-80,6) e valor preditivo negativo de 70% (IC 95% 35,3-91,9). A IRM apresentou sensibilidade de 91,6% (IC 95% 71,5-98,5) e especificidade de 36,8% (IC 95% 17,2-61,3), com valor preditivo positivo de 64,7% (IC 95% 46,4-79,6) e valor preditivo negativo de 77,7% (IC 95% 40,1-96). As diferenças de sensibilidade e especificidade, áreas sob as curvas ROC e os índices de Youden não foram significativas. A concordância dos resultados da VEEG e da IRM foi moderada (k=0,599; p<0,01; IC 95% 0,468-0,730).
Patients with drug-resistant epilepsy frequently have extrahippocampal lesions as etiology. A large proportion of these patients might benefit from lesionectomy for the reduction of seizures. For surgery to be undertaken, it is usually performed both long-term videoelectroencephalography monitoring (VEEG) and magnetic resonance imaging of the brain (MRI) for the precise delimitation of the epileptogenic zone, the region that must be resected for seizure control. In the present study, the diagnostic accuracy of VEEG and MRI were studied in the localization of the epileptogenic zone in patients with focal cortical dysplasia. The seizure-onset zone (VEEG) and the region of epileptogenic lesion (MRI) were compared whereas concordant or discordant regarding surgery region. Medical charts of 209 patients were reviewed, being the reference standard (surgery region) and post-surgical follow-up longer than 12 months available in 43 patients. Videoelectroencephalography has a sensitivity of 85.7% (95% CI 62.6-96.2) and specificity of 41.1% (95% CI 19.4-66.5), with positive predictive value of 64.2% (95% CI 44.1-80.6) and negative predictive value of 70% (95% CI 35.3-91.9). Magnetic resonance imaging has a sensitivity of 91.6% (95% CI 71.5-98.5) and specificity of 36.8% (95% CI 17.2-61.3), with positive predictive value of 64.7% (95% CI 46.4-79.6) and negative predictive value of 77.7% (95% CI 40.1-96). The differences of sensitivity and specificity, areas under the ROC curves and Youden\'s indexes were not significant. The concordance between the results of VEEG and MRI was moderate (k=0.599; p<0.01; 95% CI 0.468-0.730).

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21

Sanches, Patrícia [UNESP]. "Imagem de tensor de difusão na epilesia de lobo temporal mesial." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/136218.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Objetivo: Epilepsia de lobo temporal mesial (ELTM) é a epilepsia refratária mais comum do adulto. A esclerose hipocampal (EH) é a alteração estrutural mais frequentemente relacionada a esta doença. Técnicas quantitativas de análise de difusão permitem a análise mesoscópica in vivo da fisiopatologia das epilepsias. O objetivo deste estudo foi analisar a variação dos principais parâmetros de difusão e explorar as diferenças entre duas metodologias de análise voxel à voxel de imagens comparando um grupo de pacientes com ELTM com controles. Métodos: Foram selecionados pacientes com diagnóstico de ELTM. Os pacientes e um grupo controle foram submetidos a ressonância magnética de 3 Tesla. Os parâmetros de difusão foram obtidos das imagens. Com base nos tensores, um template customizado foi criado e as imagens registradas em um espaço padrão. Três formas de comparação de cada parâmetro foram realizadas: morfometria baseada em voxel (VBM), estatística espacial baseada em tratos (TBSS) e analise especifica de tratos. Resultados: Foram investigados 24 pacientes com ELTM e 36 controles. 10 apresentaram EH à esquerda, 11 à direita e três bilateral com predomínio à esquerda. Nos pacientes, o VBM mostrou as maiores alterações localizadas no giro parahipocampal direito (aumento de difusão axial, radial e média; volumes de 290, 758 e 595 mm3; p = 0,001, < 0,0001 e < 0,0001 respectivamente) e no lobo temporal esquerdo (redução de anisotropia fracionada; 719 mm3; p < 0,0001). Nos pacientes, o TBSS mostrou as maiores alterações no giro temporal superior esquerdo (aumento de difusão axial; 423 mm3; p = 0,028), no lobo temporal esquerdo (aumento da difusão radial; 1132 mm3; p = 0,001), no uncus direito (aumento da difusão média; 254 mm3; p = 0,008) e no lobo temporal esquerdo (redução de anisotropia fracionada; volume de 17518 mm3; p < 0,001). Conclusão: As técnicas utilizadas mostraram resultados semelhantes. Entretanto, as análises se complementaram reforçando a significância dos achados. As alterações foram mais frequentemente observadas nos parâmetros de anisotropia fracionada e difusão radial indicando a necessidade do uso de múltiplos parâmetros de difusão para investigação de pacientes com ELMT. Foi possível observar um predomínio de alterações nas adjacências do lobo temporal mas alterações mais difusas também foram detectadas bem como maior comprometimento no lado esquerdo.
Objectives: Mesial temporal lobe epilepsy (MTLE) is the most common refractory epilepsy of adults. Hippocampal sclerosis (HS) is the most frequent structural abnormality associated with this disease. Quantitative techniques of diffusion analysis allow an in vivo mesoscopic analysis the epilepsy physiopathology. The objective of this investigation was to analyze the variation of the main diffusion parameters and explore differences between two methodologies of voxel-wise neuroimaging analysis, comparing a group of patients with MTLE to controls. Methods: Patients with MTLE and controls were selected. All patients and controls were underwent 3 Tesla magnetic resonance imaging. Diffusion parameters were obtained from the raw images. Based on the tensors, a customized template was created and images were transformed into standard space. Three comparisons for each parameter were performed: voxel-based morphometry (VBM), tract based spatial statistics (TBSS) and specific tract analysis. Results: 24 patients with MTLE and 36 controls were investigated. 10 patients presented with left HS, 11 with right and 3 bilateral with left predominance. VBM showed major abnormalities localized in the right parahippocampal gyrus (increased axial, radial and mean diffusivity; volumes 290, 758 and 595 mm3; p = 0.001, < 0.0001 and < 0.0001, respectively) and in the left temporal lobe (decreased fractional anisotropy; 719 mm3; p < 0.0001). TBSS showed major abnormalities in the left superior temporal gyrus (increased axial diffusivity; 423 mm3; p = 0.028), in the left temporal lobe (increased radial diffusivity; 1132 mm3; p = 0.001), in the right uncus (increased mean diffusivity; 254 mm3; p = 0.008) and in the left temporal lobe (decreased fractional anisotropy; volume 17518 mm3; p < 0.001). Conclusion: The two techniques used showed similar findings. The analyses were complementary, stressing the significance of the findings. The abnormalities were more frequently observed in fractional anisotropy and radial diffusivity indicating the need for several diffusion parameters in the investigation of patients with MTLE. We observed a predominance of abnormalities in the temporal lobe adjacencies but diffuse abnormalities and a major burden of the left side were also observed.
FAPESP: 2011/02961-2

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22

Sanches, Patrícia. "Imagem de tensor de difusão na epilesia de lobo temporal mesial." Botucatu, 2016. http://hdl.handle.net/11449/136218.

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Orientador: Luiz Betting
Resumo: Objetivo: Epilepsia de lobo temporal mesial (ELTM) é a epilepsia refratária mais comum do adulto. A esclerose hipocampal (EH) é a alteração estrutural mais frequentemente relacionada a esta doença. Técnicas quantitativas de análise de difusão permitem a análise mesoscópica in vivo da fisiopatologia das epilepsias. O objetivo deste estudo foi analisar a variação dos principais parâmetros de difusão e explorar as diferenças entre duas metodologias de análise voxel à voxel de imagens comparando um grupo de pacientes com ELTM com controles. Métodos: Foram selecionados pacientes com diagnóstico de ELTM. Os pacientes e um grupo controle foram submetidos a ressonância magnética de 3 Tesla. Os parâmetros de difusão foram obtidos das imagens. Com base nos tensores, um template customizado foi criado e as imagens registradas em um espaço padrão. Três formas de comparação de cada parâmetro foram realizadas: morfometria baseada em voxel (VBM), estatística espacial baseada em tratos (TBSS) e analise especifica de tratos. Resultados: Foram investigados 24 pacientes com ELTM e 36 controles. 10 apresentaram EH à esquerda, 11 à direita e três bilateral com predomínio à esquerda. Nos pacientes, o VBM mostrou as maiores alterações localizadas no giro parahipocampal direito (aumento de difusão axial, radial e média; volumes de 290, 758 e 595 mm3; p = 0,001, < 0,0001 e < 0,0001 respectivamente) e no lobo temporal esquerdo (redução de anisotropia fracionada; 719 mm3; p < 0,0001). Nos pacientes, o ... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Objectives: Mesial temporal lobe epilepsy (MTLE) is the most common refractory epilepsy of adults. Hippocampal sclerosis (HS) is the most frequent structural abnormality associated with this disease. Quantitative techniques of diffusion analysis allow an in vivo mesoscopic analysis the epilepsy physiopathology. The objective of this investigation was to analyze the variation of the main diffusion parameters and explore differences between two methodologies of voxel-wise neuroimaging analysis, comparing a group of patients with MTLE to controls. Methods: Patients with MTLE and controls were selected. All patients and controls were underwent 3 Tesla magnetic resonance imaging. Diffusion parameters were obtained from the raw images. Based on the tensors, a customized template was created and images were transformed into standard space. Three comparisons for each parameter were performed: voxel-based morphometry (VBM), tract based spatial statistics (TBSS) and specific tract analysis. Results: 24 patients with MTLE and 36 controls were investigated. 10 patients presented with left HS, 11 with right and 3 bilateral with left predominance. VBM showed major abnormalities localized in the right parahippocampal gyrus (increased axial, radial and mean diffusivity; volumes 290, 758 and 595 mm3; p = 0.001, < 0.0001 and < 0.0001, respectively) and in the left temporal lobe (decreased fractional anisotropy; 719 mm3; p < 0.0001). TBSS showed major abnormalities in the left superior temporal... (Complete abstract click electronic access below)
Mestre

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23

MELO, Michel Gomes de. "Desempenho de memória em paciente com epilepsia do lobo temporal: contribuições das subpartes da formação hipocampal." Universidade Federal de Pernambuco, 2016. https://repositorio.ufpe.br/handle/123456789/20020.

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A Epilepsia do Lobo Temporal (ELT) é a forma mais refratária ao tratamento farmacológico. Esse tipo de epilepsia tem origem nas estruturas do lobo temporal, sendo o hipocampo uma das estruturas mais afetadas, apresentando diminuição do volume e, consequentemente, gliose, caracterizando a Esclerose Hipocampal (EH). É sabido que o hipocampo desenvolve importante papel no processo mnemônico, sendo o déficit de memória a alteração mais importante nesses pacientes. Neste contexto, o presente trabalho tem como objetivo investigar a relação do desempenho de memória nos pacientes com ELT com as subpartes da formação hipocampal. Trata-se de um estudo retrospectivo, transversal, analítico, utilizando imagens de ressonância magnética (IRM) e escores de testes neuropsicológicos de memória verbal e visual, obtidos a partir de um grupo de 60 pacientes atendidos no Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto, da Universidade de São Paulo, no período de 2008 a 2011. Para a obtenção dos volumes das subpartes da formação hipocampal das IRM, foi utilizado a segmentada automática pelo software FreeSurfer®, obtendo os volumes da cauda do hipocampo, pré-subículo, CA1, CA2/3, CA4/GD, subículo, fímbria e fissura hipocampal. Posteriormente, foram correlacionadas com variáveis clínicas e escores de memória. A análise das imagens revelou atrofia generalizada nas subpartes da formação hipocampal ipsilateral (EH), exceto da fissura hipocampal. Essa redução do volume interferiu diretamente no desempenho de memória verbal e visual, desses pacientes. Os pacientes com EH à direita apresentaram déficit significativos na memória visual. Já os pacientes com EH à esquerda, apresentaram déficit na memória verbal e na memória visual. Foi possível avaliar, também, que a atrofia na região CA1 está relacionada com a diminuição do desempenho de memória declarativa e que os danos no CA2/3 e CA4/GD estão envolvidos com baixo desempenho das memórias de longo prazo. Neste contexto, é possível concluir que o desempenho de memória depende de uma rede de integração integra e não só de regiões especializadas. Concluímos, também, que tanto a memória verbal, quando a memória visual, possui um hemisfério dominante, no entanto, o hemisfério não dominante, quando lesionado, também interfere do desempenho de memória.
The Temporal Lobe Epilepsy (TLE) is the most resistant form of epilepsy to pharmacology treatment. This epilepsy type has its origin on the temporal lobe, which the hippocampus is one of the most affected structures, presenting volume decreasing and gliosis, characterizing the Hippocampal Sclerosis (HE). It is known that the hippocampus has an important role in the mnemônnico process and the memory deficit is the most important change in these patients. So, this work aims to investigate the relationship between the memory development in the TLE patients and the hippocampal formation subparts. It is a retrospective study, transversal, analytic, using Magnetic Resonance Images (MRI) and verbal and visual memory neuropsychological tests scores obtained from a group of 60 (sixty) patients from the Hospital das Clínicas of the Ribeirão Preto Medical School, University de São Paulo between 2008 and 2011. To measure the hippocampal formation subparts volume of IRM, it was used the automatic segmented by the FreeSurfer® software, getting the volume of the hipocampo tail, presubículum, CA1, CA2/3, CA4/DG, subiculum, fímbria and hippocampal fissure, that had been correlated with clinical variables and memory scores. The image analysis revealed a general atrophy in the hippocampal formation subparts, except the hippocampal fissure. This volume reduction had directly interfered in the declarative memory performance, verbal and visual, of these patients. The Right HE patients, presented significant visual memory deficit. The Left EH patients presented both verbal and visual memory deficit. It was also possible to evaluate that CA1 region atrophy is related to the declarative memory performance decrease and the damage in the CA2/3 and CA4/DG are related to the low performance of the long term memories. In this way, we conclude that memory performance depends on a whole integration network and not only an specific region. We also conclude that both verbal and visual memory has a dominant hemisphere, eventhough damages to the non dominant hemisphere will also interfere in te memory performance.

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24

Bergo, Felipe Paulo Guazzi 1978. "Segmentação de displasias corticais focais em imagens de ressonancia magnetica do cerebro humano." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/276092.

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Orientador: Alexandre Xavier Falcão
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Computação
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Resumo: O diagnóstico médico por imagem é uma tarefa complexa, que depende da avaliação subjetiva de um grande volume de dados. Diversas possibilidades de patologia não são consideradas por limitação de tempo e especialização dos profissionais da área médica, mesmo quando os exames adequados estão disponíveis. O desenvolvimento de técnicas automáticas de auxílio ao diagnóstico é um avanço importante para simplificar a tarefa do médico, descartando um grande número de patologias ou indicando as localizações mais prováveis de eventuais anormalidades patológicas. Displasias corticais focais (FCDs) estão associadas à epilepsia, e são uma das causas mais comuns de casos de epilepsia refratária, em que o tratamento medicamentoso não é suficiente para controlar as crises. As FCDs são lesões que geram variações locais e sutis na aparência do tecido em imagens de ressonância magnética (RM). Seu diagnóstico é em geral uma tarefa difícil e subjetiva. Detecção e localização de eventuais lesões de FCD são passos fundamentais para o planejamento do tratamento do paciente. Neste trabalho propomos um método para segmentação automática de FCDs em imagens de ressonância magnética (RM) tri-dimensional do cérebro humano. Desenvolvemos novas técnicas de segmentação e análise de imagens, automatizamos uma técnica previamente interativa (reformatação curvilinear) e, através de classificação por aprendizado supervisionado, obtivemos detecção de 100% das lesões, com cobertura de 76,9% dos voxels lesionais. Este resultado é um pouco melhor que o estado da arte, embora ainda não seja uma solução ideal, solidamente validada, para o problema
Abstract: Medical diagnosis from imaging techniques is a complex task that depends on subjective evaluation of a large volume of data. Many pathologies are often not considered due to time and experience restrictions of the medical crew, even when the imaging data are readily available. The development of computer-aided diagnosis techniques greatly simplify the physician¿s work, by discarding a large number of pathologies and/or pointing out the most probable locations of pathological abnormalities. Focal cortical displasia (FCDs) are associated to epilepsy, and are one of the most common causes of refractory epilepsy, where drug-based treatment does not eliminate the seizures. FCDs are lesions that lead to subtle, localized appearance variations of brain tissue in magnetic resonance (MR) imaging. Their diagnosis is difficult, tedious and subjective. Detection and localiation of FCD lesions are key steps for treatment planning. In this work we propose a method for automatic segmentation of FCDs in tridimensional magnetic MR images of the human brain. We developed new image segmentation and image analysis techniques, automated a previously interactive technique (curvilinear reformatting) and, through classification by supervised learning, achieved detection of 100% of the lesions, with 76,9% coverage of the lesional voxels. This result is slightly better than the state-of-the-art, even though it still is has not been thoroughly validated on a large data base and can still be improved.
Doutorado
Doutor em Ciência da Computação

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25

Tenney, Jeffrey R. "Functional MRI of Rat and Monkey Models of Absence Epilepsy: A Dissertation." eScholarship@UMMS, 2004. https://escholarship.umassmed.edu/gsbs_diss/17.

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A seizure is defined as an abnormal electrical discharge from the brain that results in the affected area losing its normal function and reacting uncontrollably. A particular subset of seizures, known as absence seizures, are characterized by brief, paroxysmal losses of consciousness that are associated with bilaterally synchronous 3 Hz spike and wave discharges (SWDs) on electroencephalography (EEG). The optimal way to understand any disease state is to study it within the human. Unfortunately, well controlled experiments in humans are difficult due to small patient populations, treatment medications which alter the seizure, and the ethical problems associated with invasive experimental procedures. Animal models of absence seizures provide a means of avoiding the above difficulties but the model should mimic, as closely as possible, the human condition. The goal of this thesis was to develop an animal model of absence epilepsy that could be used to explore, non-invasively, the underlying mechanisms of absence seizures. Functional magnetic resonance imaging (fMRI) was used to non-invasively monitor brain activity during absence seizures in various animal models. In this dissertation I report the development of a pharmacological rat model of absence seizures for use in fMRI investigations. Imaging was performed after absence seizure induction using γ-butyrolactone (GBL) and it was found that the cortico-thalamic circuitry, critical for the formation of SWDs, showed robust signal changes consistent with electroencephalographic recordings in the same animals. Since a major disadvantage of the GBL rat model is that it produces acute, drug-induced seizures, a genetic rat model with spontaneous absence seizures was subsequently developed for fMRI. EEG-triggered fMRI was used to identify areas of brain activation during spontaneous SWDs in the epileptic WAG/Rij rat strain under awake conditions. Significant signal changes were apparent in several areas of the cortex and several important nuclei of the thalamus. These results draw an anatomical correlation between areas in which there is increased fMRI signal and those where SWDs have been previously recorded using electrophysiologic techniques. One way in which absences differ between humans and both of these rat models is that the SWD frequency in humans is classically 3 Hz while in rats it varies from 7 to 11 Hz. Marmoset monkeys were found to model the human absence seizure condition better than other animals because GBL administration in these non-human primates results in the formation of 3 Hz SWDs. This monkey model was developed for awake functional imaging and changes in signal intensity in the thalamus and sensorimotor cortex correlated with the onset of 3 Hz SWDs. The change in BOLD signal intensity was bilateral but heterogeneous, affecting some brain areas more than others.

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Pozdin, Maksym O. "Automated Extraction of Subdural Grid Electrodes from Post-Implant MRI Scans for Epilepsy Surgery." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4979.

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The objective of the current research was to develop an automated algorithm with no or little user assistance for extraction of Subdural Grid Electrodes (SGE) from post-implant MRI scans for epilepsy surgery. The algorithm utilizes the knowledge about the artifacts created by Subdural Electrodes (SE) in MRI scans. Also the algorithm does not only extract individual electrodes, but it also extracts them as a SGE structures. Information about the number and type of implanted electrodes is recorded during the surgery [1]. This information is used to reduce the search space and produce better results. Currently, the extraction of SGE from post-implant MRI scans is performed manually by a technologist [1, 2, 3]. It is a time-consuming process, requiring on average a few hours, depending on the number of implanted SE. In addition, the process does not conserve the geometry of the structures, since electrodes are identified individually. Usually SGE extraction is complicated by nearby artifacts, making manual extraction a non-trivial task that requires a good visualization of 3D space and orientation of SGE in it. Currently, most of the technologists use 2D slice viewers for extraction of SGE from 3D MRI scans. There is no commercial software to perform the automated extraction task. The only algorithm suggested in the literature is [4]. The goal of the proposed algorithm is to improve the performance of the algorithm in [4]. As a goal, the proposed algorithm performs extraction of SGE not only for individual electrodes, but by applying geometric constraints on SGE.

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Robles, Ana Paula Valadares. "Estudo prospectivo das funções cognitivas em epilepsia idiopática da infância através da ressonância magnética funcional." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/5/5151/tde-09022015-104627/.

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Introdução: Uma importante aplicação da técnica de Ressonância Magnética funcional é em pesquisa clínica, acerca das funções cognitivas de pacientes, como por exemplo atenção, memória, linguagem, dentre outras. Pacientes com Epilepsia Idiopática da Infância podem apresentar déficits cognitivos e não possuem alterações estruturais detectáveis o que facilita a aplicação de técnicas computacionais de registro e normalização em estudos de neuroimagem o que possibilita a geração de imagens de um grupo de indivíduos e suas diversas possibilidades de inferências estatísticas. Este estudo teve como objetivo descrever as funções cognitivas em pacientes com Epilespia Rolândica (ER) e Epilepsia de Ausência (EA) através da RMf. Métodos: 57 indíviduos, 23 pacientes com ER ((média= 10,7 anos), 20 pacientes com EA (média= 9,9 anos) e 14 controles saudáveis (média=10 anos) foram submetidos ao vídeo-EEg, testes neuropsicológicos para avaliação das funções cognitivas (QI, funções executivas, dentre outras) e um paradigma de atenção Stoptask Gonogo e um paradigma Resting State (RS). Os dados foram analisados e foram gerados mapas limirializados de ativação da função BOLD. Resultados: As principais áreas ativas em pacientes e controles no paradigma Stoptask foram: hemisférios cerebelares bilateral, córtex orbito frontal bilateral, giros fusiformes, ínsula bilateral, córtex dorso latero pré-frontal, giro do Cíngulo anterior direito e esquerdo, bordas dos sulcos intraparietais, giros frontais superiores, eye-field.(p < 0,01). No paradigma RS as áreas encontradas foram: Córtex medial prefrontal, giro angular, giro supramarginal, giro do cíngulo posterior, giro frontal superior, sulco intraparietal, área motora suplementar, córtex prefrontal lateral (p < 0,05). OS mapas comparativos de grupos mostraram diferenças em ativaçao entre pacientes e controles. Discussão: Nossos mapas de ativação da resposta BOLD são semelhantes aos encontrados por outros autores na literatura tanto no paradigma Stoptask quanto no RS. As diferenças entre os grupos são devido aos deficits cognitivos que os pacientes apresentam. Conclusões: Crinaças com ER e EA apresentam deficits cognitivos e hipofrontalidade, mais estudos são necessários para melhoir entendimento da extensão dos deficits cognitivos em Epilepsia Idiopática da Infância
Introduction: An important application of functional MRI is in clinical research about the cognitive functions of patients, such as attention, memory, language, among others. Patients with Idiopathic Epilepsy of Childhood may show cognitive deficits and have no detectable structural changes which facilitates the application of computational techniques and standardization of registration in neuroimaging studies, which enables to obtain a group map of individuals and their various possibilities for statistical inferences. This study aimed to describe the cognitive functions in patients with Rolandic Epilepsy (RE) and absence epilepsy (AE) by fMRI. Methods: 57 individuals, 23 patients with RE (mean = 10.7 years), 20 patients with AE (mean = 9.9 years) and 14 healthy controls (mean = 10 years) underwent video-EEG, neuropsychological tests for assessment of cognitive function (IQ, executive functions, amongothers) theu also perform an attention paradigm Stoptask Gonogo and the Resting State (RS). Data were analyzed and maps were generated for BOLD activation function. Results: The main areas active in patients and controls in the paradigm Stoptask were bilateral cerebellar hemispheres, bilateral frontal orbital cortex, fusiform gyrus, bilateral insula, dorsal lateral prefrontal cortex, anterior cingulate gyrus right and left edges of the intraparietal sulcus, superior frontal gyrus, eye -field. (p < 0.01). In the RS paradigm areas observed were: medial prefrontal cortex, angular gyrus, supramarginal gyrus, posterior cingulate gyrus, superior frontal gyrus, intraparietal sulcus, supplementary motor area, lateral prefrontal cortex (p < 0.05). there were no statistically significant differences between group means (p < 0,01)Discussion: Our activation maps of BOLD response are similar to those found by other authors in the literature both in Stoptask paradigm as in the RS. The diferences between groups may be due cognitive deficts in patients group. Conclusions: Patients with RE and AE presente cognitive impairment and hypofrontality, more studies are necessary for better understanding of the extension of the cognitive deficits in Idiophatic Childhood Epilepsy patients

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Lobato, Mauricio Lima. "Epilepsias generalizadas idiopáticas: fatores clínicos e de neuroimagem relacionados ao difícil controle medicamentoso." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/5/5138/tde-23102018-103029/.

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As epilepsias generalizadas idiopáticas (EGIs) associam-se a controle satisfatório de crises e a exames de neuroimagem convencionais normais. Métodos de neuroimagem avançada, como DTI (diffusion tensor imaging) e VBM (voxel based morphometry), permitiram melhor compreensão dos mecanismos envolvidos no comportamento clínico das EGIs. O objetivo do estudo foi avaliar diferenças clínicas entre pacientes com EGI não refratária e refratária, assim como avaliar as diferenças entre pacientes com EGI não refratária, refratária e indivíduos saudáveis através de ressonância por DTI e VBM. Avaliamos 40 pacientes com características clínicas e eletrencefalográficas de EGI, sendo 22 pacientes com EGI não refratária (GNR) e 18 pacientes com EGI refratária (GR). Participaram do estudo 20 indivíduos saudáveis, os quais compuseram o grupo controle (GC). O grupo GR apresentava maior número de pacientes usuários de fármacos benzodiazepínicos (p=0,01) e de fármacos antiepilépticos não-valproato (p=0,02). Pacientes do grupo GR também utilizavam doses maiores de VPA que os pacientes do grupo GNR (p=0,03) e recebiam maior carga total média de fármacos antiepilépticos (p=0,04). Observou-se, em relação aos 16 feixes e tratos avaliados nos índices de DTI (AF, DM, DR, DA) que houve diferença estatística do grupo GNR em relação ao GC em duas áreas do índice AF (anisotropia fracional), seis áreas do índice DM (difusividade média), seis áreas do índice DR (difusividade radial) e seis áreas do índice DA (difusividade axial), assim como houve diferença estatística do grupo GR em relação ao GC em duas áreas do índice AF, sete áreas do índice DM, seis áreas do índice DR e três áreas do índice DA. Entre as 94 regiões estudadas por VBM, observou-se redução volumétrica estatística em nove áreas de interesse no GNR quando em comparação ao GC e em sete áreas de interesse no GR quando em comparação ao GC. Não se observaram diferenças entre os grupos GNR e GR nos parâmetros avaliados por DTI ou por VBM. Como esperado, observamos que pacientes com EGI refratária mais frequentemente utilizam fármacos antiepilépticos de segunda linha ou não habituais a este tipo de epilepsia. O estudo permitiu concluir que o comprometimento encefálico nas EGIs analisadas é difuso e envolve áreas habitualmente não associadas a estas epilepsias, como o hipocampo e outras áreas temporais, e que os achados imagenológicos não se associam à refratariedade clínica dos pacientes
Generalized idiopathic epilepsies (IGEs) are usually associated with good seizure control and normal conventional neuroimaging exams. Advanced neuroimaging methods, such as DTI (diffusion tensor imaging) and VBM (voxel based morphometry) have provided a better understanding of the IGEs. This study´s primary objective was to evaluate clinical diferences between refractory and non-refractory IGEs, and to compare advanced MRI methods (DTI and VBM) findings in refractory and non-refractory IGE patients. Forty IGE patients were divided in two groups: 22 non-refratory (NRG) patients and 18 refractory (RG) patients. Twenty healthy subjects were enrolled as a control group (CG). RG patients received benzodiazepines (p=0,01) and non-valproate antiepileptic drugs (p=0,02) more often than NRG patients. RG group also received a higher mean total of antiepileptic drug load (p=0,04) than NRG group. Regarding neuroimaging methods, DTI index analysis (FA, MD, RD, AD) statiscally demonstrated that NRG group had two compromised areas on FA (fractional anisotropy) index, six areas on MD (mean diffusivity) index, six areas on RD (radial diffusivity) index and six areas on AD (axial diffusivity) index, when compared to CG. On RG group, DTI index analysis statiscally demonstrated that this group had two compromised areas on FA index, seven areas on MD index, six areas on RD index and three areas on AD index, when compared to CG, of 16 analyzed areas of interest. VBM analysis of 94 regions of interest showed reduced volumes in nine areas in the NRG group when compared to CG and in seven areas of interest in the RG group when compared to CG. We found no differences on DTI and VBM parameters comparing NRG and RG groups. As expected, refractory IGE patients received second line or non-usual antiepileptic drugs for this epilepsy type more often than non-refractory patients. We concluded that brain involvement´s in IGEs is diffuse and affects areas usually not related to this epilepsy type, such as the hipocampus and other temporal areas. Advanced neuroimaging findings in IGEs were not associated with clinical refractoriness

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Fujisao, Elaine Keiko. "Análise das descargas epileptiformes interictais na epilepsia de lobo temporal mesial utilizando análise quantitativa do eletroencefalograma e da neuroimagem." Botucatu, 2018. http://hdl.handle.net/11449/153535.

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Orientador: Luiz Betting
Resumo: FUJISAO, E.K. Análise das descargas epileptiformes interictais (IED) na epilepsia de lobo temporal mesial utilizando análise quantitativa do eletroencefalograma e da neuroimagem. Doutorado – Faculdade de Medicina de Botucatu, Universidade Estadual Paulista ―Júlio de Mesquita Filho‖, Botucatu, 2018. Objetivos: Investigar áreas de correlação entre a substância cinzenta e mapas de fonte interictal nos subtipos de epilepsia de lobo temporal mesial (ELTM). Introdução: Na ELTM, os eletroencefalogramas (EEG) de rotina de escalpo interictais mostram descargas epileptiformes na região temporal anterior revelando a circuitaria epileptiforme. Os geradores anatômicos precisos destas descargas ainda não foram identificados. Métodos: Setenta e um pacientes e trinta e seis controles foram submetidos à ressonância magnética (RM) de3T. Imagens de alta resolução T1 foram utilizadas para análise estrutural. A segmentação do hipocampo foi realizada com o pacote Freesurfer e utilizada para confirmar a atrofia do hipocampo (AH). O software SPM foi utilizado para segmentação da matéria cinzenta, registro e análise estatística. Os pacientes também foram submetidos à EEG de rotina com eletrodos temporais anteriores adicionais. Para cada paciente, as descargas epileptiformes foram selecionadas, promediadas e a fonte foi extraída com o algoritmo CLARA incluído no software BESA. Finalmente, a análise de correlação voxel-wise foi realizada entre a matéria cinzenta suavizada e os mapas de origem EEG em su... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: FUJISAO, E.K. Analysis of interictal epileptiform discharges (IED) in mesial temporal lobe epilepsy using quantitative EEG and neuroimaging. PhD - Medical School of Botucatu City, State University of São Paulo "Júlio de Mesquita Filho", Botucatu, 2018. Aims: To investigate areas of correlation between gray matter and interictal EEG source maps in subtypes of mesial temporal lobe epilepsy (MTLE). Background: In MTLE, routine interictal scalp EEG typically shows epileptiform discharges over the anterior temporal region disclosing the epileptogenic circuitry. The precise anatomical generators of these discharges have not yet been identified. Methods: 71 patients and 36 controls underwent to 3T MRI. High resolution T1 images were used for structural analysis. Hippocampal segmentation was performed with Freesurfer package and used to confirm hippocampal atrophy (HA). SPM software was used for segmentation of the gray matter, registration and statistical analysis. Patients were also submitted to routine EEG with additional anterior temporal electrodes. For each patient, epileptiform discharges were selected, averaged and the source was extracted with CLARA algorithm included in the BESA´s software. Finally, voxel-wise correlation analysis was conducted between the smoothed gray matter and EEG source maps in distinct mTLE subtypes. Results: 16 patients had mTLE without HA, 154 discharges were evaluated (67 left and 87 right), 10826mm³ were correlated involving extra-temporal regions... (Complete abstract click electronic access below)
Doutor

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Fujisao, Elaine Keiko [UNESP]. "Análise das descargas epileptiformes interictais na epilepsia de lobo temporal mesial utilizando análise quantitativa do eletroencefalograma e da neuroimagem." Universidade Estadual Paulista (UNESP), 2018. http://hdl.handle.net/11449/153535.

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FUJISAO, E.K. Análise das descargas epileptiformes interictais (IED) na epilepsia de lobo temporal mesial utilizando análise quantitativa do eletroencefalograma e da neuroimagem. Doutorado – Faculdade de Medicina de Botucatu, Universidade Estadual Paulista ―Júlio de Mesquita Filho‖, Botucatu, 2018. Objetivos: Investigar áreas de correlação entre a substância cinzenta e mapas de fonte interictal nos subtipos de epilepsia de lobo temporal mesial (ELTM). Introdução: Na ELTM, os eletroencefalogramas (EEG) de rotina de escalpo interictais mostram descargas epileptiformes na região temporal anterior revelando a circuitaria epileptiforme. Os geradores anatômicos precisos destas descargas ainda não foram identificados. Métodos: Setenta e um pacientes e trinta e seis controles foram submetidos à ressonância magnética (RM) de3T. Imagens de alta resolução T1 foram utilizadas para análise estrutural. A segmentação do hipocampo foi realizada com o pacote Freesurfer e utilizada para confirmar a atrofia do hipocampo (AH). O software SPM foi utilizado para segmentação da matéria cinzenta, registro e análise estatística. Os pacientes também foram submetidos à EEG de rotina com eletrodos temporais anteriores adicionais. Para cada paciente, as descargas epileptiformes foram selecionadas, promediadas e a fonte foi extraída com o algoritmo CLARA incluído no software BESA. Finalmente, a análise de correlação voxel-wise foi realizada entre a matéria cinzenta suavizada e os mapas de origem EEG em subtipos ELTM distintos. Resultados: 16 pacientes apresentaram ELTM sem AH, foram avaliadas 154 descargas (67 à esquerda e 87 à direita), 10826 mm³ correlacionadas envolvendo regiões extra-temporais (lobos frontal e parietal, r = -0,78, x = 19, y = 61, z = 6). 22 pacientes tinham AH esquerda, 839 descargas foram avaliadas (818 à esquerda e 21 à direita), 2700 mm3 foram correlacionadas envolvendo o lobo temporal esquerdo (r = -0,56, x = -28, y = -5, z = -19). 21 pacientes tinham AH direita, foram avaliadas 910 descargas (139 à esquerda e 771 à direita), 3625 mm3 foram correlacionadas envolvendo o giro frontal inferior direito (r = -0,70, x = 32, y = 33, z = 8). 12 pacientes apresentaram AH bilateral, 343 descargas foram avaliadas (264 à esquerda e 79 à direita), 4932 mm3 foram correlacionadas envolvendo principalmente a ínsula direita (r = -0,87, x = 29, y = 0, z = 8). Conclusão: Correlações negativas foram encontradas entre volumes de matéria cinzenta e imagens de origem EEG. Os geradores neuroanatômicos de IED são heterogêneos e variam de acordo com o subtipo ELTM.
FUJISAO, E.K. Analysis of interictal epileptiform discharges (IED) in mesial temporal lobe epilepsy using quantitative EEG and neuroimaging. PhD - Medical School of Botucatu City, State University of São Paulo "Júlio de Mesquita Filho", Botucatu, 2018. Aims: To investigate areas of correlation between gray matter and interictal EEG source maps in subtypes of mesial temporal lobe epilepsy (MTLE). Background: In MTLE, routine interictal scalp EEG typically shows epileptiform discharges over the anterior temporal region disclosing the epileptogenic circuitry. The precise anatomical generators of these discharges have not yet been identified. Methods: 71 patients and 36 controls underwent to 3T MRI. High resolution T1 images were used for structural analysis. Hippocampal segmentation was performed with Freesurfer package and used to confirm hippocampal atrophy (HA). SPM software was used for segmentation of the gray matter, registration and statistical analysis. Patients were also submitted to routine EEG with additional anterior temporal electrodes. For each patient, epileptiform discharges were selected, averaged and the source was extracted with CLARA algorithm included in the BESA´s software. Finally, voxel-wise correlation analysis was conducted between the smoothed gray matter and EEG source maps in distinct mTLE subtypes. Results: 16 patients had mTLE without HA, 154 discharges were evaluated (67 left and 87 right), 10826mm³ were correlated involving extra-temporal regions (frontal and parietal lobes; r=-0.78, x=19, y=61, z=6). 22 patients had left HA, 839 discharges were evaluated (818 left and 21 right), 2700mm3 were correlated involving the left temporal lobe (r=-0.56, x=-28, y=-5, z=-19). 21 patients had right HA, 910 discharges were evaluated (139 left and 771 right), 3625mm3 were correlated involving the right inferior frontal gyrus (r=-0.70, x=32, y=33, z=8). 12 patients had bilateral HA, 343 discharges were evaluated (264 left and 79 right), 4932mm3 were correlated mainly involving the right insula (r=-0.87, x=29, y=0, z=8). Conclusion: Negative correlations were disclosed between gray matter volumes and EEG source imaging. Neuroanatomical generators of interictal discharges are heterogeneous and vary according to mTLE subtype.

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Salah, Eddin Anas. "Network Construction and Graph Theoretical Analysis of Functional Language Networks in Pediatric Epilepsy." FIU Digital Commons, 2013. http://digitalcommons.fiu.edu/etd/971.

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This dissertation introduces a new approach for assessing the effects of pediatric epilepsy on the language connectome. Two novel data-driven network construction approaches are presented. These methods rely on connecting different brain regions using either extent or intensity of language related activations as identified by independent component analysis of fMRI data. An auditory description decision task (ADDT) paradigm was used to activate the language network for 29 patients and 30 controls recruited from three major pediatric hospitals. Empirical evaluations illustrated that pediatric epilepsy can cause, or is associated with, a network efficiency reduction. Patients showed a propensity to inefficiently employ the whole brain network to perform the ADDT language task; on the contrary, controls seemed to efficiently use smaller segregated network components to achieve the same task. To explain the causes of the decreased efficiency, graph theoretical analysis was carried out. The analysis revealed no substantial global network feature differences between the patient and control groups. It also showed that for both subject groups the language network exhibited small-world characteristics; however, the patient’s extent of activation network showed a tendency towards more random networks. It was also shown that the intensity of activation network displayed ipsilateral hub reorganization on the local level. The left hemispheric hubs displayed greater centrality values for patients, whereas the right hemispheric hubs displayed greater centrality values for controls. This hub hemispheric disparity was not correlated with a right atypical language laterality found in six patients. Finally it was shown that a multi-level unsupervised clustering scheme based on self-organizing maps, a type of artificial neural network, and k-means was able to fairly and blindly separate the subjects into their respective patient or control groups. The clustering was initiated using the local nodal centrality measurements only. Compared to the extent of activation network, the intensity of activation network clustering demonstrated better precision. This outcome supports the assertion that the local centrality differences presented by the intensity of activation network can be associated with focal epilepsy.

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Moita, Luanna. "Avaliação das alterações estruturais talâmicas em pacientes com epilepsia do lobo temporal com esclerose hipocampal e suas possíveis associações com déficits de linguagem e a presença de sintomas depressivos." Universidade Federal de Pernambuco, 2015. https://repositorio.ufpe.br/handle/123456789/16920.

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CAPEs
Introdução: A epilepsia do lobo temporal medial (ELTM) é o tipo de epilepsia mais comum e refratária. Apesar do nome, esta doença não está limitada ao lobo temporal, podendo também afetar o tálamo e interferir em funções cognitivas, como a linguagem. Essas implicações podem estar associadas a presença de sintomas depressivos. Objetivo: Avaliar, através de ressonância magnética quantitativa alterações estruturais do tálamo e as relacionar com variáveis clínicas, com o desempenho na linguagem e com a presença de sintomas depressivos. Metodologia: Trata-se de um estudo do tipo retrospectivo, transversal e analítico por amostra de conveniência. Os dados foram obtidos a partir de um grupo de pacientes atendidos no Hospital das Clínicas de Ribeirão Preto, da Universidade de São Paulo, no período de novembro de 2008 a 2011. A casuística foi composta por 63 pacientes (37 com lesão à direita), sendo 34 (53,96%) indivíduos do sexo feminino e 29 (46,04%) do sexo masculino, com média de idade de 41 anos (±10,14). O grupo controle foi composto por 91 indivíduos saudáveis sendo 41 (45,05%) do sexo feminino e 50 (54,95%) do sexo masculino, com média de idade de 41 anos (±17,33). Para as análises foram utilizadas medidas quantitativas de ressonância magnética do tálamo (volume, taxa de transferência da magnetização e relaxometria), dados clínicos (frequência de crise, tempo de doença e presença de sintomas depressivos), nível de escolaridade e avaliação da linguagem pelo teste de FAS e TNB. Resultados: Foi encontrado menor volume do tálamo no grupo ELTM Ipsilateral em relação ao Contralateral. Em relação aos controles, houve diferença significativa do volume do tálamo epiléptico no gênero masculino. Houve uma tendência de menor volume do tálamo com maior o tempo de doença. Já a frequência da crise não interferiu nas análises de volume dos pacientes com ELT-EH. A Transferência de Magnetização foi menor nos grupos de pacientes com ELTM Ipsilateral e Contralateral Esquerdos em relação ao Controle Esquerdo. A relaxometria foi maior no tálamo contralateral do paciente em relação ao controle. Não houve correlação da relaxometria com o tempo de doença e a frequência de crise. A doença parece interferir na capacidade de resposta ao teste FAS, visto que 94,6% dos doentes apresentam escores abaixo do esperado, o mesmo não foi observado no teste de TNB. Foi encontrado correlação dos sintomas depressivos com a relaxometria. O tálamo Ipsilateral do grupo com sintomas depressivos apresentou maior tempo de relaxometria que grupo ELTM Ipsilateral sem sintomas depressivos. Conclusão: A epilepsia do lobo temporal altera o volume e a integridade do tálamo, sendo os sintomas depressivos um fator agravante, e tal alteração parece influenciar negativamente na função da linguagem.
Introduction: Epilepsy medial temporal lobe (TLE) is the most common type of epilepsy and refractory epilepsy. Despite its name, this disease is not limited to the temporal lobe, and may also affect the thalamus and interfere with cognitive functions such as language. These implications may be associated with depressive symptoms. Objective: To evaluate, using quantitative magnetic resonance imaging of the thalamus structural changes and relate to clinical variables with performance in language and with the presence of depressive symptoms. Methodology: This is a study of retrospective type, cross-sectional analytical sample by convenience. Data were obtained from a group of patients treated at the Hospital of Ribeirão Preto, University of São Paulo, from November 2008 to 2011. The sample consisted of 63 patients (37 with injury to the right) and 34 (53.96%) females and 29 (46.04%) were male, with a mean age of 41 years (± 10.14). The control group had consisted of 91 healthy individuals and 41 (45.05%) and the 50 females (54.95%) were male, with a mean age of 41 years (± 17.33). For the analysis we used quantitative measures of magnetic resonance imaging of the thalamus (volume, throughput magnetization and relaxometry), clinical data (crisis frequency, duration of disease and presence of depressive symptoms), educational attainment and language evaluation by test FAS and TNB. Results: It was found smaller volume of the thalamus in MTLE Ipsilateral group compared to the contralateral. Regarding the controls, a significant difference from epileptic thalamic volume in males. There was a trend of lower volume of the thalamus with greater disease duration. Since the frequency of the crisis did not affect the volume of analyzes of patients with TLE-EH. The magnetization transfer was lower in groups of patients with MTLE ipsilateral and contralateral Left against the Left Control. The relaxometry was greater in the contralateral thalamus the patient compared to the control. There was no correlation of relaxometry with disease duration and frequency of crisis. The disease appears to interfere with responsiveness to FAS test, since 94.6% of patients have scores lower than expected, it was not observed in TNB test. It was found correlation of depressive symptoms with relaxometry. The ipsilateral thalamus the group with depressive symptoms had a higher time relaxometry that group MTLE Ipsilateral without depressive symptoms. Conclusion: The temporal lobe epilepsy changes the structure of the thalamus, and depressive symptoms an aggravating factor, and this change seems to influence the function of language.

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Cunha, Heitor Hakime. "Desenvolvimento de um software para geração de redes complexas formadas a partir de estimativas de conectividade cerebral: um estudo da espessura cortical no cérebro de indivíduos saudáveis e pacientes com epilepsia." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/59/59135/tde-14032014-104256/.

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O cérebro humano é considerado uma rede complexa em termos estruturais e funcionais em diferentes escalas. A caracterização da arquitetura desta rede pode ser considerada uma importante ferramenta no auxílio ao estudo de diferentes doenças neurodegenerativas. No presente estudo propusemos um software desenvolvido em JAVA para investigar esta arquitetura com base na correlação estatística de características morfológicas entre diferentes regiões do córtex. Foram utilizados dados de espessura cortical obtidos a partir de imagens de ressonância magnética de 191 indivíduos saudáveis e 93 pacientes com epilepsia. Foi proposto um modelo não linear para considerar o efeito da idade na espessura cortical com identificação de duas etapas: amadurecimento e envelhecimento. Os pacientes, quando comparados aos controles, apresentaram uma redução significativa na espessura cortical fundamentalmente nas regiões para-central, pericalcarina e do pré-cuneo no hemisfério direito. Esta diminuição também se manifestou ao longo da idade, com uma maior taxa de queda na região parahipocampal direita. Considerando a conectividade anatômica aqui calculada, o grupo de pacientes evidenciou alterações em 31\\% das possíveis conexões e de forma difusa. Adicionalmente, nas redes cerebrais dos pacientes houve uma diminuição de 15\\% no comprimento médio do caminho e no coeficiente de agrupamento. Aplicando-se um algoritmo de agrupamento, foram detectadas três comunidades para os indivíduos saudáveis e seis comunidades para os pacientes, confirmando uma quebra de organização estrutural neste ultimo grupo. Com este software esperamos trazer à comunidade mais uma ferramenta para análise das conexões cerebrais e suas modificações em determinadas patologias, contribuindo com seu entendimento e possível diagnóstico.
The human brain can be characterized as a complex network structurally and functionally in different levels. The description of the architecture of this network can be considered an important tool in understanding different neurodegenerative diseases. In the present study, we developed a software in JAVA to investigate this architecture based on statistical correlation of morphological characteristics between different cortex areas. It was used a database of cortical thickness obtained from magnetic resonance images of 191 healthy subjects and 93 patients with epilepsy. It was implemented a non-linear model to consider the effect of age in cortical thickness with identification of 2 stages: maturation and aging. The patients, when compared to healthy subjects, showed a significant reduction in cortical thickness, particularly at the areas precentral, pericalcarine and pré-cuneus of right hemisphere. This decrease also could be noted through the age, with a higher decrease rate at the right parahipocampal area. Considering the anatomical connectivity calculated, the patients group showed diffuse changes in 31\\% of the possible connections. Furthermore, in the patients brain network it was found a decrease of 15\\% in the characteristic path length and clustering coefficient. By applying a clustering algorithm, 3 clusters were detected in the healthy subjects and 6 clusters in the patients, confirming a breakdown of the structural organization in this last group. With our software we hope to bring to the community another tool to improve the brain connectivity analysis and its modifications in some pathologies, contributing with its understanding and possible diagnosis.

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Mankinen, K. (Katariina). "Neuropsychological performance and functional MRI findings in children with non-lesional temporal lobe epilepsy." Doctoral thesis, Oulun yliopisto, 2014. http://urn.fi/urn:isbn:9789526203546.

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Abstract The purpose of the present work was to investigate whether children with non-lesional temporal lobe epilepsy (TLE) have deficits in neuropsychological performance and whether the possible deficits can be investigated using functional magnetic resonance imaging (fMRI). In this population-based study, 21 children aged 8-15 with non-lesional TLE and a normal intelligence quotient were evaluated and compared with 21 healthy, age- and gender-matched controls. Neuropsychological assessments, clinical examinations, electroencephalography (EEG) and structural and functional MRI were performed on all the subjects. Three fMRI methods were used: resting-state regional homogeneity, resting-state functional connectivity and task-induced blood oxygenation level-dependent activation. The patients with non-lesional TLE showed good neuropsychological performance on average, although the girls were found to have significant problems in several neuropsychological tests. The deficits were not restricted to elements of performance involving the classical temporal lobe memory system but were also found in tests requiring frontal and parietal lobe functioning. Early onset of epilepsy and duration of epilepsy had significant negative effects on neuropsychological performance. All the fMRI methods detected significant functional differences between the TLE patients and the healthy controls, not only in the temporal lobes but also in broad networks extending to the frontal, parietal and thalamic areas. These differences seemed to differ markedly in location between the TLE patients depending on the interictal EEG findings. Neuropsychological performance results were supported by the fMRI findings, implying that TLE should be regarded as a widespread disruption of the brain networks and not just malfunction of a single region in the brain within these networks. This needs to be taken into consideration when evaluating learning abilities among TLE patients even at an early stage in epilepsy
Tiivistelmä Tutkimuksen tarkoituksena oli selvittää onko lapsilla, jotka sairastavat tuntemattomasta syystä aiheutuvaa ohimolohkoepilepsiaa, neuropsykologisia ongelmia ja aiheuttavatko mahdolliset ongelmat aivojen toiminnallisessa magneettikuvauksessa nähtäviä muutoksia. Tähän väestöpohjaiseen tutkimukseen otettiin 21 tuntemattomasta syystä ohimolohkoepilepsiaa sairastavaa normaaliälyistä 8-15-vuotiaista lasta ja verrattiin heitä 21 terveeseen, ikä- ja sukupuolivakioituun kontrollihenkilöön. Kaikille tutkimukseen osallistuneille tehtiin neuropsykologinen tutkimus, kliininen tutkimus, aivosähkökäyrä sekä rakenteellinen ja toiminnallinen aivojen magneettikuvaus. Toiminnallisessa magneettikuvauksessa käytettiin veren happipitoisuudesta riippuvaista (engl. blood oxygenation level-dependent) kontrastia kuvantamaan levossa aivojen paikallista homogeniteettia (engl. regional homogeneity) ja toiminnallista kytkennällisyyttä (engl. functional connectivity) sekä kognitiivisten tehtävien herättämiä aktivaatio-vasteita. Tuntemattomasta syystä ohimolohkoepilepsiaa sairastavien lasten neuropsykologinen suoriutuminen oli keskimäärin hyvää, vaikkakin tytöillä oli nähtävillä tilastollisesti merkitseviä ongelmia useissa eri testeissä. Ongelmat eivät rajoittuneet pelkästään klassisiin ohimolohkoalueen muistitoimintoihin, vaan niitä havaittiin myös otsa- ja päälakilohkojen toimintoja edellyttävissä testeissä. Varhainen sairastumisikä ja epilepsian kesto heikensivät suoriutumista tilastollisesti merkitsevästi osatesteissä, joissa tarvittiin näönvaraisen hahmottamisen taitoja, psykomotorista nopeutta ja työmuistia. Ohimolohkoepilepsiaa sairastavien ja terveiden kontrollien aivoissa löydettiin toiminnallisia eroja kaikilla toiminnallisen magneettikuvauksen menetelmillä. Eroja ei todettu ainoastaan ohimolohkoissa, vaan niitä löytyi myös otsa- ja päälakilohkoon sekä tyvitumakealueelle ylettyvissä laaja-alaisissa hermoverkostoissa. Epilepsiapotilailla erojen paikantuminen riippui kohtaustenvälisestä aivosähkökäyrälöydöksestä. Neuropsykologisen suoriutumisen tulokset tukevat toiminnallisen magneettikuvauksen löydöksiä kuvastaen temporaaliepilepsian olevan laaja-alainen hermoverkostojen häiriö eikä pelkästään tietyn aivoalueen toiminnan häiriö. Tämä tulee huomioida arvioitaessa ohimolohkoepilepsiaa sairastavien lasten oppimiskykyä jo epilepsian alkuvaiheessa

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35

El, Azami Meriem. "Computer aided diagnosis of epilepsy lesions based on multivariate and multimodality data analysis." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI087/document.

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Environ 150.000 personnes souffrent en France d'une épilepsie partielle réfractaire à tous les médicaments. La chirurgie, qui constitue aujourd’hui le meilleur recours thérapeutique nécessite un bilan préopératoire complexe. L'analyse de données d'imagerie telles que l’imagerie par résonance magnétique (IRM) anatomique et la tomographie d’émission de positons (TEP) au FDG (fluorodéoxyglucose) tend à prendre une place croissante dans ce protocole, et pourrait à terme limiter de recourir à l’électroencéphalographie intracérébrale (SEEG), procédure très invasive mais qui constitue encore la technique de référence. Pour assister les cliniciens dans leur tâche diagnostique, nous avons développé un système d'aide au diagnostic (CAD) reposant sur l'analyse multivariée de données d'imagerie. Compte tenu de la difficulté relative à la constitution de bases de données annotées et équilibrées entre classes, notre première contribution a été de placer l'étude dans le cadre méthodologique de la détection du changement. L'algorithme du séparateur à vaste marge adapté à ce cadre là (OC-SVM) a été utilisé pour apprendre, à partir de cartes multi-paramétriques extraites d'IRM T1 de sujets normaux, un modèle prédictif caractérisant la normalité à l'échelle du voxel. Le modèle permet ensuite de faire ressortir, dans les images de patients, les zones cérébrales suspectes s'écartant de cette normalité. Les performances du système ont été évaluées sur des lésions simulées ainsi que sur une base de données de patients. Trois extensions ont ensuite été proposées. D'abord un nouveau schéma de détection plus robuste à la présence de bruit d'étiquetage dans la base de données d'apprentissage. Ensuite, une stratégie de fusion optimale permettant la combinaison de plusieurs classifieurs OC-SVM associés chacun à une séquence IRM. Enfin, une généralisation de l'algorithme de détection d'anomalies permettant la conversion de la sortie du CAD en probabilité, offrant ainsi une meilleure interprétation de la sortie du système et son intégration dans le bilan pré-opératoire global
One third of patients suffering from epilepsy are resistant to medication. For these patients, surgical removal of the epileptogenic zone offers the possibility of a cure. Surgery success relies heavily on the accurate localization of the epileptogenic zone. The analysis of neuroimaging data such as magnetic resonance imaging (MRI) and positron emission tomography (PET) is increasingly used in the pre-surgical work-up of patients and may offer an alternative to the invasive reference of Stereo-electro-encephalo -graphy (SEEG) monitoring. To assist clinicians in screening these lesions, we developed a computer aided diagnosis system (CAD) based on a multivariate data analysis approach. Our first contribution was to formulate the problem of epileptogenic lesion detection as an outlier detection problem. The main motivation for this formulation was to avoid the dependence on labelled data and the class imbalance inherent to this detection task. The proposed system builds upon the one class support vector machines (OC-SVM) classifier. OC-SVM was trained using features extracted from MRI scans of healthy control subjects, allowing a voxelwise assessment of the deviation of a test subject pattern from the learned patterns. System performance was evaluated using realistic simulations of challenging detection tasks as well as clinical data of patients with intractable epilepsy. The outlier detection framework was further extended to take into account the specificities of neuroimaging data and the detection task at hand. We first proposed a reformulation of the support vector data description (SVDD) method to deal with the presence of uncertain observations in the training data. Second, to handle the multi-parametric nature of neuroimaging data, we proposed an optimal fusion approach for combining multiple base one-class classifiers. Finally, to help with score interpretation, threshold selection and score combination, we proposed to transform the score outputs of the outlier detection algorithm into well calibrated probabilities

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Rondina, Jane Maryam. "Aplicação de imagens funcionais por de ressonancia magnetica adquiridas mediante estimulos de memorização no estudo de pacientes com epilepsia do lobo temporal medial e controles : analise de regiões de interesse." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/309294.

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Orientador: Fernando Cendes
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas
Made available in DSpace on 2018-08-11T18:31:26Z (GMT). No. of bitstreams: 1 Rondina_JaneMaryam_D.pdf: 1600669 bytes, checksum: 1ea760868c65fb9012161a1d5b9c3efa (MD5) Previous issue date: 2008
Resumo: Este trabalho teve como objetivo a aquisição, processamento e análise de imagens funcionais por ressonância magnética através da aplicação de estímulos para o estudo de processos relacionados à memória verbal e visual em controles e em pacientes com epilepsia do lobo temporal medial associada a atrofia hipocampal. As imagens foram adquiridas pela sequência EPI (Echo-planar Imaging) e o sinal BOLD (Blood-oxygenation-level-dependent) obtido foi analisado de forma multivariada. O contraste entre as condições definidas no desenho do experimento foi analisado estatisticamente através da utilização do teste t-student. Foram realizadas comparações entre diferentes abordagens de processamento das imagens. Foi realizada uma análise de regiões de interesse (ROIs) com o objetivo de explorar as condições definidas no projeto do experimento e avaliar o envolvimento de estruturas anatômicas temporais e frontais no processo de codificação de memória. Foram discutidas questões sobre a utilização de diferentes abordagens de análise individual e de grupo, sobre o planejamento do paradigma e desenho do experimento, sobre o padrão de ativação das estruturas anatômicas consideradas sob diferentes condições e sobre diferenças observadas entre os grupos de pacientes e o grupo de controles
Abstract: The purpose of this work was the acquisition, processing and analysis of functional magnetic resonance images through the application of stimuli for the study of processes related to both verbal and visual memory in both controls and patients with medial temporal lobe epilepsy associated to hippocampal atrophy. The images were acquired using the EPI (Echo-planar Imaging) protocol and the BOLD (Blood-oxygenation-level-dependent) signal was analyzed using a multivariate approach. The contrast between the conditions defined in the design was statistically analyzed using t-test. Voxelwise analysis was performed for comparison among different approaches and ROI (Region of interest) analysis was performed aiming both to explore the conditions defined in the design and to study the involvement of anatomical structures considered (both temporal and frontal) in the memorizing process. Conclusions were obtained about: the use of different analysis approaches; the planning of paradigm and design definition; the activation patterns observed in the anatomical structures considered during the different conditions; and differences observed among the patients and control groups
Doutorado
Ciencias Biomedicas
Doutor em Ciências Médicas

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37

Nicolás, Berenguer Berta. "Exploring autobiographical memories: from neurocognitive mechanisms to real-life experience." Doctoral thesis, Universitat de Barcelona, 2020. http://hdl.handle.net/10803/671642.

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Our daily life event experiences fall into two general classifications: those that are remembered and those that are not. The act of remembering involves a perfect gearing of neurocognitive operations that begin with the encoding of information and conclude with the retrieval of a complete memory. The success or failure of any of these operations will determine the fate of a memory. Capturing memory processes and their dysfunction in real-life situations is technically and methodologically challenging. Therefore, much basic and clinical memory research uses highly controlled materials and tasks, recorded by pen and paper or on a computer in a laboratory setting. While such an approach is extremely powerful in allowing good experimental control and straight-forward analysis of many parameters, such artificial paradigms fail to provide valid conclusions on function and impairment in naturalistic real-life situations. In this thesis, we explored some of the factors that can influence the encoding and retrieval of memories with the aim of developing novel approaches that enhance ecological validity. Relative to the process of encoding, in Study 1, we studied how the integration of new information into long-term memory takes place when novel experiences overlap with existing structures of memory networks. In particular, we focused on understanding whether the nature of these overlapping representations, either at episodic or semantic level, could affect the process of integration into a relational memory network. Our neurophysiological results supported the notion that different neural responses and mechanisms subserved memory integration processes and they differed as a function of the underlying relational network properties. Given its clinical relevance, we also examined the role of the hippocampus in inferential learning by exploring the generalization ability of a group of TLE patients with specific lesions at the MTL structures. Our behavioural results showed that the hippocampus is a key structure that support mnemonic generalization. In study 2, we propose a novel naturalistic approach that share the overall aim of bridging the gap between the highly controlled yet artificial laboratory studies and the more ecologically-valid processes that occur in everyday life. In this study, we developed a new experimental approach that allowed us to extract individual experiences from real-life episodic routine and used them as cues by using a convolution network-based algorithm (SR-clustering). With these individual cues we also explored how the pass of time impacted on the retrieval of these event episodes assessing their recollection one week, two weeks and 6 to 12 months after the encoding period. Additionally, participants also enrolled into a separate study that require them to encode and retrieve lab-based pictures, not related with their personal experiences, to delineate the feasible differences between retrieval processes cued by real-life autobiographical vs lab-based event experiences. Our behavioural results suggested that picture cues were effective in eliciting the retrieval of Autobiographical Memories (AMs). Furthermore, from our neurophysiological results we observed that these ‘cues’ clearly triggered a solid differential response when compared to pictures depicting other’s past. In study 3, we used functional Magnetic Resonance Imaging (fMRI) to investigate the brain regions engaged during the retrieval of AMs for single event episodes cued by pictures recorded by healthy adults through a wearable camera for 4 consecutive days. The findings of this study corroborate that the use of real-life picture cues elicit the activation of a core AM brain network of regions that can be observed even at the individual level. Altogether, this thesis provides novel insights into how encoding and retrieval processes unfolded and contributed to exciting and debated topics about the cognitive and neural mechanisms that support autobiographical memories. I hope that the findings and the thoughts contained in this thesis would be useful to start novel research initiatives that improve our understanding of the mechanisms that govern human memory.
Nuestras vivencias del día a día se pueden clasificar entre las que recordaremos y las que no. El acto de recordar implica un perfecto engranaje de operaciones neurocognitivas que comienzan con la codificación de una información y concluyen con la recuperación completa de una memoria. El éxito o el fracaso de alguna de estas operaciones determinará el destino de esa memoria. Ser capaces de capturar estos procesos y sus errores en situaciones de la vida real es metodológica y técnicamente un reto. Por lo tanto, mucha de la investigación básica y clínica en el campo de la memoria utiliza estímulos y tareas en condiciones controladas, administradas en lápiz y papel o en un ordenador en un entorno de laboratorio. Aunque este enfoque cuenta con puntos fuertes en el control experimental y en el análisis directo de muchos parámetros, estos paradigmas artificiales no son capaces de ofrecer conclusiones válidas que expliquen la función y el deterioro en la vida real. En esta tesis, hemos explorado algunos de los factores que pueden influenciar la codificación y recuperación de la memoria con el esfuerzo de desarrollar nuevos enfoques que aumenten la validez ecológica. Referente al proceso de codificación, en el estudio 1, estudiamos cómo tiene lugar la integración de una nueva información en la memoria a largo plazo cuando se solapa con estructuras de redes de memoria ya existentes. En particular, nos centramos en entender si la naturaleza de estas representaciones solapadas, tanto a nivel episódico como semántico, pueden afectar al proceso de integración en una red de memoria relacional. Nuestros resultados neurofisiológicos apoyan la idea de que diferentes respuestas y mecanismos neuronales favorecen los procesos de integración y que se diferencian en función de las propiedades relacionales de la red. Dada su relevancia clínica, examinamos también el papel que el hipocampo tiene en el aprendizaje inferencial mediante la exploración de la habilidad para generalizar de un grupo de pacientes con epilepsia en el lóbulo temporal y con lesiones específicas en el lóbulo temporal medial. Nuestros resultados conductuales mostraron que el hipocampo es una de las estructuras principales que sustenta la generalización. En el estudio 2, proponemos un enfoque nuevo que abarca el objetivo general de establecer puentes entre estudios artificiales que estén altamente controlados a nivel experimental con procesos más ecológicos que ocurren en el día a día. En este estudio, desarrollamos un protocolo que nos permitió extraer experiencias individuales de las rutinas diarias y usarlas como pistas de recuperación aplicando un algoritmo (SR-Clustering). Con estas pistas de recuperación tomadas individualmente, exploramos también cómo el paso del tiempo impacta en la recuperación de los eventos episódicos al evaluar el recuerdo a una semana, dos semanas y de 6 a 12 meses del periodo de codificación. Además, los participantes también formaron parte de otro estudio donde se les requería que codificaran y recuperaran imágenes artificiales creadas en el laboratorio, y que no tenían ninguna relación con sus experiencias personales, para delimitar posibles diferencias entre los procesos de recuperación generados a partir de experiencias autobiográficas comparadas con las de laboratorio. Nuestros resultados conductuales sugieren que las fotografías utilizadas fueron efectivas ya que provocaron la recuperación de memorias autobiográficas. Además, nuestros resultados neurofisiológicos mostraron que estas pistas de recuperación eran capaces de producir una clara y sólida respuesta diferente a la producida por fotografías que mostraban el pasado de otras personas. En el estudio 3, usamos resonancia magnética funcional (fMRI) para investigar las regiones del cerebro que se activan al recuperar memorias autobiográficas usando fotografías tomadas por adultos sanos con una cámara portátil durante 4 días consecutivos. Los hallazgos de este estudio corroboran que el uso de imágenes reales provoca la activación de una red central de regiones relacionadas con la memoria autobiográfica que pueden observarse a nivel individual. En resumen, esta tesis ofrece nuevas ideas acerca de cómo se desenvuelven los procesos de codificación y recuperación de la memoria, y contribuye a fomentar el debate existente entre los mecanismos cognitivos y neuronales que sostienen la memoria autobiográfica. Espero que los hallazgos y pensamientos que contiene esta tesis puedan ser útiles para fomentar nuevas investigaciones y mejorar el entendimiento de los mecanismos que gobiernan la memoria humana.

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Ozelo, Helka Fabbri Broggian. "Desenvolvimento de uma técnica multimodal associando eletroencefalografia e imagens funcionais por ressonância magnética para o estudo de memória operacional : aplicação em indivíduos com epilepsia de lobo temporal mesial associada a atrofia hipocampal." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/277110.

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Orientador: Roberto Jose Maria Covolan
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin
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Resumo: Neste trabalho, uma técnica multimodal envolvendo eletroencefalografia (EEG) e imagens funcionais por Ressonância Magnética (fMRI) foi implementada a fim de realizar estudos sobre memória operacional em um grupo de indivíduos, incluindo controles e pacientes com epilepsia do lobo temporal mesial (ELTM) associada à atro½a hipocampal esquerda. Para isso, uma série de testes de memória foram implementados. Estes testes foram baseados em um paradigma em blocos dividido em períodos de codificação e retenção de memória, otimizados com relação ao tempo de duração para que se adequassem tanto à análise de EEG quanto para a análise de fMRI. O paradigma foi apresentado aos indivíduos no primeiro momento durante a aquisição de EEG e posteriormente durante a aquisição de fMRI. Os dados de EEG indicaram a presença de oscilações theta (4-8 Hz) na região do córtex frontal e oscilações alfa (9-12 Hz) na região do córtex parieto-occipital, em ambos os grupos durante todo o período de codi.cação. No entanto, durante a retenção só foi observada a presença do ritmo alfa nas regiões mais posteriores, envolvendo principalmente as áreas temporo-parietais. Diferentemente do que é encontrado na literatura, foram estabelecidas correlações entre esses ritmos e respostas BOLD tanto positivas quanto negativas, envolvendo diferentes regiões cerebrais. No entanto, estas áreas de ativação e de desativação não eram concorrentes, mas sim vizinhas ou contralaterais. Embora ambos os grupos, controles e pacientes, tenham apresentado um desempenho semelhante na realização dos testes, houve discrepâncias entre os dois grupos com relação às estruturas corticais envolvidas na tarefa. Durante a codi.cação, o grupo controle apresentou a predominância de áreas de ativação no hemisfério cerebral esquerdo, enquanto que no grupo de pacientes a ativação foi igualmente distribuída entre os dois hemisférios. Esse achado sugere o fenômeno de neuroplasticidade, no qual áreas corticais adicionais seriam recrutadas para compensar as estruturas afetadas pela atrofia
Abstract: In this work, a multimodal approach involving electroencefalography (EEG) and functional Magnetic Resonance Imaging (fMRI) was implemented in order to perform studies on working memory in a group of subjects including controls and patients with mesial temporal lobe epilepsy (MTLE) associated with left hippocampal atrophy. In order to do that, a series of memory tests were implemented. These tests were based on a block paradigm containing epochs of memory codification and memory retention, optimized with respect to the time to fit both analysis of EEG and fMRI. The paradigm was presented to subjects for the first time during EEG acquisition and later during fMRI acquisition. EEG data indicated the presence of theta oscillations (4-8 Hz) in the frontal region and alpha oscillations (9-12 Hz) in the parieto-occipital region, in both groups. In the retention period, it was only observed the presence of the alpha rhythm in the posterior region, involving mainly the temporo-parietal regions. Diÿerently from what is found in the literature, correlations were established among these rhythms and both, positive and negative BOLD responses, but in diÿerent regions. Activation and deactivation zones were detected for all epochs. The deactivation zones were found not only in the neighborhood of the activation regions, but frequently in the homologous regions. Although both groups, controls and patients, presented similar performance for the memory tests, there were discrepancies between these groups in terms of the cortical structures involved in the memory task. In the control group, it was found predominance of activation at the left hemisphere whereas for the patient group activation was predominantly lateralized to the right, probably due to damage in the mesial temporal lobe structures. Such a finding is suggestive of the neuroplasticity phenomenon by which additional cortical areas would be recruited to compensate the structures affected by atrophy
Doutorado
Física Médica
Doutor em Ciências

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Mäkiranta, M. (Minna). "EEG and BOLD-contrast fMRI in brain:cerebrovascular reactivity, suppression of neuronal activity, global and local brain injury." Doctoral thesis, University of Oulu, 2004. http://urn.fi/urn:isbn:9514274296.

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Abstract The purpose of the present study was to gain more insight into the blood oxygen level-dependent (BOLD)-contrast functional MRI (fMRI) in the brain and its connection to EEG, both in global and local scales of their temporal and spatial relations. BOLD signal changes were studied during hyperventilation (HV) induced EEG reactivity of intermittent rhythmic delta activity (IRDA). The BOLD signal in gray matter decreased 30% more in subjects with IRDA (N = 4) than in controls (N = 4), during the first two minutes of HV. This difference disappeared during IRDA in EEG. BOLD signal changes may provide additional information about dynamic hemodynamic changes relative to HV induced EEG reactivity. BOLD signal changes were investigated during sudden deepening of thiopental anesthesia into EEG burst-suppression level in pigs (N = 5). Positive (6–8%) or negative (-3– -8%) group average BOLD signal changes correlated to the thiopental bolus injection were seen. Positive and negative responses covered 1.6% and 2.3% of the brain voxels, respectively. BOLD signal changes in brain are associated with sudden deepening of thiopental anesthesia into EEG burst-suppression level, but they are spatially inconsistent and scarce. Somatosensory BOLD response was studied in brain before and after globally induced methotrexate (MTX) exposition in pigs (N = 4). After the MTX exposure, reduced (from 2–4% to 0–1%) or negative (-2% to -3%) BOLD responses were detected. Somatosensory BOLD-contrast response shows a slight difference in brain before and after globally induced MTX exposition. An experimental epilepsy model for development of simultaneous EEG and BOLD-contrast fMRI in the localization of epilepsy was developed and tested. Dynamic penicillin induced local epilepsy was applied in deep isoflurane anesthesia in pigs (N = 6). Relatively high (10–20%) and localized BOLD signal increase was found. The dynamic penicillin induced focal epilepsy model in deep isoflurane anesthesia with simultaneous EEG and BOLD-contrast fMRI is feasible for the development of these methods for localization of epileptic focus or foci. In conclusion, with careful experimental design and analysis, BOLD-contrast fMRI with EEG provides a potential tool for monitoring and localising functional changes in the brain.

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Boux, Fabien. "Méthodes statistiques pour l'imagerie vasculaire par résonance magnétique : application au cerveau épileptique." Thesis, Université Grenoble Alpes, 2020. http://www.theses.fr/2020GRALM068.

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L'objectif de ce travail de thèse est l'exploration de l'imagerie par résonance magnétique (IRM) pour l'identification et la localisation des régions du cerveau impliquées dans l'épilepsie mésio-temporale. Précisément, les travaux visent 1) à optimiser un protocole d'IRM vasculaire sur un modèle animal d'épilepsie et 2) à concevoir une méthode de quantification de cartes IRM vasculaires basée sur la modélisation de la relation entre signaux IRM et paramètres biophysiques.Les acquisitions IRM sur un modèle expérimental murin d'épilepsie mésio-temporale avec sclérose de l'hippocampe ont été effectuées sur un scanner 9.4 T. Les données collectées ont permis de quantifier sept cartes IRM cellulaires et vasculaires quelques jours après l'état de mal épileptique puis plus tard, lorsque les crises spontanées sont apparues.Ces paramètres ont été employés pour l'identification automatique des régions épileptogènes et des régions de propagation des crises. Afin d'augmenter la détection de petites variations des paramètres IRM chez les individus épileptiques, une méthode de quantification basée sur la résonance magnétique fingerprinting est développée. Cette méthode consiste à identifier, parmi un ensemble de signaux simulés, le plus proche du signal IRM acquis et peut être vue comme un problème inverse qui présente les difficultés suivantes : le modèle direct est non-linéaire et provient d'une série d'équations sans expression analytique simple; les signaux en entrée sont de grandes dimensions; les vecteurs des paramètres en sortie sont multidimensionnels. Pour ces raisons, nous avons utilisé une méthode de régression inverse afin d'apprendre à partir de simulation la relation entre l'espace des paramètres et celui des signaux. Dans un domaine largement dominé par les approches d'apprentissage profond, la méthode proposée se révèle très compétitive fournissant des résultats plus précis. De plus, la méthode permet pour la première fois de produire un indice de confiance associé à chacune des estimations. En particulier, cet indice permet de réduire l'erreur de quantification en rejetant les estimations associées à une faible confiance.Actuellement, aucun protocole clinique permettant de localiser avec précision le foyer épileptique ne fait consensus. La possibilité d'une identification non-invasive de ces régions est donc un premier pas vers un potentiel transfert clinique
The objective of this thesis is the investigation of magnetic resonance imaging (MRI) for the identification and localization of brain regions involved in mesio-temporal lobe epilepsy (MTLE). Precisely, the work aims 1) at optimizing a vascular MRI protocol on an animal model of epilepsy and 2) at designing a method to quantify vascular MRI maps based on the modeling of the relationship between MRI signals and biophysical parameters.MRI acquisitions on an experimental mouse model of MTLE with hippocampal sclerosis were performed on a 9.4 T scanner. The data collected allowed the quantification of seven cellular and vascular MRI maps a few days after the epileptic condition and later when the spontaneous seizures emerged. These parameters were used for the automatic identification of epileptogenic regions and regions of seizure propagation. To enhance the detection of small variations in MRI parameters in epileptic subjects, a quantification method based on magnetic resonance fingerprinting has been developed. This method consists in identifying, among a set of simulated signals, the closest one to the acquired signal. It can be seen as an inverse problem that presents the following difficulties: the direct model is non-linear, as a complex series of equations or simulation tools; the inputs are high-dimensional signals; and the output is multidimensional. For these reasons, we used an appropriate inverse regression approach to learn a mapping between signal and biophysical parameter spaces. In a field widely dominated by deep learning approaches, the proposed method is very competitive and provides more accurate results. Moreover, the method allows for the first time to produce a confidence index associated with each estimate. In particular, this index allows to reduce the quantification error by discarding estimates associated with low confidence.So far no clinical protocol emerges as a consensus to accurately localize epileptic foci. The possibility of a non-invasive identification of these regions is therefore a first step towards a potential clinical transfer

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Sonkajärvi, E. (Eila). "The brain's electrical activity in deep anaesthesia:with special reference to EEG burst-suppression." Doctoral thesis, Oulun yliopisto, 2015. http://urn.fi/urn:isbn:9789526209722.

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Abstract Several anaesthetics are able to induce a burst-suppression (B-S) pattern in the electroencephalogram (EEG) during deep levels of anaesthesia. A burst-suppression pattern consists of alternating high amplitude bursts and periods of suppressed background activity. All monitors measuring the adequacy of anaesthesia recognize the EEG B-S as one criterion. A better understanding of EEG burst-suppression is important in understanding the mechanisms of anaesthesia. The aim of the study was to acquire a more comprehensive understanding of the function of neural pathways during deep anaesthesia. The thesis is comprised of four prospective clinical studies with EEG recordings from 64 patients, and of one experimental study of a porcine model of epilepsy with EEG registrations together with BOLD fMRI during isoflurane anaesthesia (II). In study I, somatosensory cortical evoked responses to median nerve stimulation were studied under sevoflurane anaesthesia at EEG B-S levels. In study III, The EEGs of three Parkinson`s patients were observed to describe the characteristics of B-S during propofol anaesthesia using scalp electrodes and depth electrodes in the subthalamic nucleus. In study IV, EEG topography was observed in 20 healthy children under anaesthesia mask induction with sevoflurane. Twenty male patients were randomized to either controlled hyperventilation or spontaneous breathing groups for anaesthesia mask induction with sevoflurane in study V. EEG alterations in relation to haemodynamic responses were examined in studies IV and V. Somatosensory information reached the cortex even during deep anaesthesia at EEG burst-suppression level. Further processing of these impulses in the cortex was suppressed. The EEG slow wave oscillations were synchronous over the entire cerebral cortex, while spindles and sharp waves were produced by the sensorimotor cortex. The development of focal epileptic activity could be detected as a BOLD signal increase, which preceded the EEG spike activity. The epileptogenic property of sevoflurane used at high concentrations especially during hyperventilation but also during spontaneous breathing together with heart rate increase, was confirmed in healthy children and male. Spike- and polyspike waveforms concentrated in a multifocal manner frontocentrally
Tiivistelmä Useat anestesia-aineet pystyvät aiheuttamaan aivosähkökäyrän (EEG) purskevaimentuman syvän anestesian aikana. Purskevaimentuma koostuu EEG:n suuriamplitudisten purskeiden sekä vaimentuneen taustatoiminnan vaihtelusta. Kaikkien anestesian syvyyttä mittaavien valvontalaitteiden toiminta perustuu osaltaan EEG:n purskevaimentuman tunnistamiseen. Tämän ilmiön parempi tunteminen on tärkeää anestesiamekanismien ymmärtämiseksi. Tutkimuksen päämääränä oli saada kattavampi käsitys hermoratojen toiminnasta syvässä anestesiassa. Väitöskirjatyö koostuu neljästä prospektiivisesta yhteensä 64 potilaan EEG-rekisteröinnit sisältävästä tutkimuksesta sekä yhdestä kokeellisen epilepsiatutkimuksen koe-eläintyöstä, jossa porsailla käytettiin isofluraanianestesiassa sekä EEG-rekisteröintejä sekä että magneettikuvantamista (fMRI) samanaikaisesti (II). Ensimmäisessä osatyössä tutkittiin keskihermon stimulaation aiheuttamia somatosensorisia herätepotentiaaleja aivokuorella EEG:n purskevaimentumatasolla sevofluraanianestesian aikana. Kolmannessa osatyössä selvitettiin propofolianestesian aiheuttamaa EEG:n purskevaimentumaa kolmelta Parkinsonin tautia sairastavalta potilaalta käyttäen sekä pintaelektrodien että subtalamisen aivotumakkeen syväelektrodien rekisteröintejä. Neljännessä osatyössä tutkittiin EEG:n topografiaa 20:llä terveeellä lapsella indusoimalla anestesia sevofluraanilla. Kaksikymmentä miespotilasta nukutettiin sevofluraanilla ja heidät satunnaistettiin joko kontrolloidun hyperventilaation tai spontaanin hengityksen ryhmiin osatyössä V. EEG-muutoksia sekä niiden yhteyttä verenkiertovasteisiin selviteltiin molemmissa osatöissä IV ja V. Omasta kehosta tuleviin tuntoärsykkeisiin liittyvä somatosensorinen informaatio saavutti aivokuoren myös syvässä EEG:n purskevaimentumatasoisessa anestesiassa. Impulssien jatkokäsittely aivokuorella oli kuitenkin estynyt. EEG:n hidasaaltotoiminta oli synkronista koko aivokuoren alueella, sen sijaan unisukkulat ja terävät aallot paikantuivat sensorimotoriselle aivokuorelle. Paikallisen epileptisen toiminnan kehittyminen oli mahdollista havaita jo ennen piikikkäiden EEG:n aaltomuotojen ilmaantumista edeltävänä BOLD-ilmiöön liittyvänä aivoverenkierron lisääntymisenä. Sevofluraanin epileptogeenisyys varmistui erityisesti hyperventilaation, mutta myös spontaanin hengityksen yhteydessä ja näihin liittyi sykkeen nousu sekä terveillä lapsilla että miehillä. Piikkejä ja monipiikkejä käsittävien aaltomuotojen keskittymistä esiintyi otsalohkon keskialueilla

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Saignavongs, Mani. "Activités Hautes Fréquences pathologiques et physiologiques dans l'épilepsie pharmaco-résistante : étude en Stéréo-Electro-Encéphalographie et couplage à l'Imagerie par Résonance Magnétique fonctionnelle." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1153.

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L'épilepsie affecte en France environ 500 000 personnes, parmi lesquelles environ un tiers présente une pharmaco-résistance. Pour ces patients, une chirurgie peut être envisagée, qui consiste en la résection de la région cérébrale à l'origine des crises, également appelée « zone épileptogène » (ZE). Le succès du traitement chirurgical repose à la fois sur la possibilité de bien circonscrire la zone nécessaire et suffisante à la survenue des crises, mais aussi sur l'identification du potentiel rôle fonctionnel du tissu cérébral situé dans ou à proximité de cette zone, afin d'éviter que l'intervention engendre des déficits cognitifs.Dans ce travail de thèse, nous nous sommes penchés sur des signaux électrophysiologiques entre 80 et 500 Hz, appelés oscillations haute fréquence (HFO), qui ont été récemment désignés comme pouvant être de nouveaux marqueurs de la ZE, et sur leurs analogues, les HFO physiologiques, qui semblent quant à eux être impliqués dans des processus cognitifs. Nous avons tenté d'identifier des paramètres permettant de distinguer ces deux classes de HFO. Alors que ces signaux sont à l'heure actuelle essentiellement enregistrés en EEG intracérébral (SEEG pour stéréo-électro-encéphalographie), nous avons également exploré la possibilité de les étudier en Imagerie par Résonnance Magnétique fonctionnelle simultanément à la SEEG, ce qui pourrait permettre à l'avenir d'en obtenir une cartographie sur l'ensemble du cerveau. La vocation générale de ces travaux est de participer à la compréhension et l'amélioration de l'étude des HFO pathologiques et physiologique, afin d'optimiser leur utilisation pour la chirurgie des épilepsies pharmaco-résistantes
Epilepsy affects 500 000 persons in France, among which about 30% will continue to have seizure despite medication. For those patients, a surgical treatment can be proposed, that consists in removing the brain region causing seizures, namely the “epileptogenic zone” (EZ). To achieve a good surgical outcome, it is necessary to identify the zone that is both necessary and sufficient for seizure start, but also, to identify the function of the brain tissue that is located close to this zone, to avoid eventual cognitive deficits.In this thesis, we were interested in the electrophysiological activities between 80 and 500 Hz called high frequency oscillations (HFO), that were recently identified as new markers of the EZ, and the analogous physiological HFO that seem to be implicated in cognitive processes. We tried to identify features that could enable to distinguish between this to class of HFO. While these activities are still mainly recorded with intra-cerebral electro-encephalography (icEEG), we also explored the possibility to study them with functional Magnetic Resonance Imaging, simultaneously with icEEG. This method could, in the future, enable to get a HFO mapping over the whole brain. The aim of this work is to participate in the comprehension and exploration improvement of pathological and physiological HFO, to enhance their use in intractable epilepsy surgery

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Castro, Bettina Pinto e. Silva Martins. "Avaliação de linguagem por ressonância magnética funcional em pacientes com epilepsia associada à esclerose mesial temporal unilateral: correlação com avaliação clínica de linguagem." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/5/5138/tde-30062016-153319/.

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Introdução: A esclerose mesial temporal (EMT) é a principal causa de epilepsia resistente ao tratamento medicamentoso. Pacientes com EMT apresentam dificuldades no processamento semântico e fonológico de linguagem e maior incidência de reorganização cerebral da linguagem (bilateral ou à direita) em relação à população geral. A ressonância magnética funcional (RMf) permite avaliar a reorganização cerebral das redes de linguagem, comparando padrões de ativação cerebral entre diversas regiões cerebrais. Objetivo: Investigar o desempenho linguístico de pacientes com EMT unilateral esquerda e direita e a ocorrência de reorganização das redes de linguagem com RMf para avaliar se a reorganização foi benéfica para a linguagem nestes pacientes. Métodos: Utilizamos provas clínicas de linguagem e paradigmas de nomeação visual e responsiva para RMf, desenvolvidos para este estudo. Foram avaliados 24 pacientes com EMTe, 22 pacientes com EMTd e 24 controles saudáveis, submetidos a provas de linguagem (fluência semântica e fonológica, nomeação de objetos, verbos, nomes próprios e responsiva, e compreensão de palavras) e a três paradigmas de linguagem por RMf [nomeação por confrontação visual (NCV), nomeação responsiva à leitura (NRL) e geração de palavras (GP)]. Seis regiões cerebrais de interesse (ROI) foram selecionadas (giro frontal inferior, giro frontal médio, giro frontal superior, giro temporal inferior, giro temporal médio e giro temporal superior). Índices de Lateralidade (ILs) foram calculados com dois métodos: bootstrap, do programa LI-Toolbox, independe de limiar, e PSC, que indica a intensidade da ativação cerebral de cada voxel. Cada grupo de pacientes (EMTe e EMTd) foi dividido em dois subgrupos, de acordo com o desempenho em relação aos controles na avaliação clinica de linguagem. O <= -1,5 foi utilizado como nota de corte para dividir os grupos em pacientes com bom e com mau desempenho de linguagem. Em seguida, comparou-se o desempenho linguístico dos subgrupos ao índices IL-boot. Resultados: Pacientes com EMT esquerda e direita mostraram pior desempenho que controles nas provas clínicas de nomeação de verbos, nomeação de nomes próprios, nomeação responsiva e fluência verbal. Os mapas de ativação cerebral por RMf mostraram efeito BOLD em regiões frontais e temporoparietais de linguagem. Os mapas de comparação de ativação cerebral entre os grupos revelaram que pacientes com EMT esquerda e direita apresentam maior ativação em regiões homólogas do hemisfério direito em relação aos controles. Os ILs corroboraram estes resultados, mostrando valores médios menores para os pacientes em relação aos controles e, portanto, maior simetria na representação da linguagem. A comparação entre o IL-boot e o desempenho nas provas clínicas de linguagem indicou que, no paradigma de nomeação responsiva à leitura, a reorganização funcional no giro temporal médio, e possivelmente, nos giros temporal inferior e superior associou-se a desempenho preservado em provas de nomeação. Conclusão: Pacientes com EMT direita e esquerda apresentam comprometimento de nomeação e fluência verbal e reorganização da rede cerebral de linguagem. A reorganização funcional de linguagem em regiões temporais, especialmente o giro temporal médio associou-se a desempenho preservado em provas de nomeação em pacientes com EMT esquerda no paradigma de RMf de nomeação responsiva à leitura
Introduction: Mesial temporal sclerosis (MTS) is the commonest cause of drug resistant epilepsy. MTS patients experience phonological and semantic processing difficulties, and increased prevalence of atypical (bilateral or right hemisphere) language dominance compared to the general population. Language reorganization can be studied with functional magnetic resonance imaging (fMRI), which allows comparison of brain activation patterns in different brain regions. Objective: To investigate performance on language tasks in patients with unilateral left and right MTS, and occurrence of atypical language dominance to determine if reorganization of language networks is beneficial to \' f . : W w y-four left MTS, 22 right MTS patients and 24 healthy controls. Subjects underwent language tasks (semantic and phonological fluency, object, verb, proper noun, and responsive naming, and word comprehension), and fMRI language paradigms [visual confrontation naming (VCN), reading responsive reading (RRN) and word generation (WG)]. Six regions of interest (ROI) (inferior frontal, middle frontal, superior frontal, inferior temporal, middle temporal and superior temporal gyri) were defined. Two language lateralization indexes (LI) were obtained for each ROI, one with a threshold-independent method using a bootstrap algorithm (LI-boot), and one that measures brain activation intensity in each voxel (Percentage Signal Change - PSC). Each patient group (left MTS and right MTS) was divided into two subgroups according to performance relative to controls in the language tasks. Z- <= -1.5 was used as a cut-off to divide patients in good and poor language performance groups. LI-boot indexes were compared between language performance subgroups. Left and right MTS patients showed worse performance than controls in verb, proper noun, and responsive naming, and verbal fluency language tasks. fMRI activation maps showed increased BOLD signal in frontal and temporoparietal language regions. Group comparison activation maps revealed that left and right MTS patients showed increased activation in homologous right hemisphere regions compared to controls. These results were corroborated by lower LI mean values for patients compared to controls, indicating greater hemispheric language representation symmetry. Comparison between LI-boot indexes and performance in language tasks showed that functional reorganization in the middle temporal, and, possibly, inferior and superior temporal gyri was associated with preserved naming performance. Conclusion: Left and right MTS patients display impaired naming and verbal fluency, as well as reorganization of the language network. Language network reorganization in the temporal regions, specially middle temporal gyrus, was associated with preserved naming in left MTS patients, in the responsive reading naming fMRI paradigm

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Lee, Kuan Jin. "Fast magnetic resonance imaging." Thesis, University of Sheffield, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.397487.

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O'Neil, Shannon M. "Magnetic resonance imaging centers /." Online version of thesis, 1994. http://hdl.handle.net/1850/11916.

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Simister, R. J. "Magnetic resonance spectroscopy as applied to epilepsy." Thesis, University College London (University of London), 2012. http://discovery.ucl.ac.uk/1348750/.

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Epilepsy is the most common serious disease of the brain. Magnetic Resonance Spectroscopy (MRS) is a novel imaging technique that offers the opportunity for co-localising biochemical information relating to metabolites specific to the study of epilepsy with high resolution MRI. Aims: The work included in this thesis was undertaken with two fundamental aims. The first was to apply a standardised MRS methodology in order to gain reproducible semi-quantitative information about the variation of relevant neuro-metabolites such as gamma amino butyric acid (GABA), glutamate (as glutamate plus glutamine [GLX]), N acetyl aspartate (NAA), myo-inositol (Ins) and creatine plus phosphocreatine (Cr) within epilepsy syndromes or pathological groups. The second main aim was to test a series of hypotheses relating to the regulation of the concentrations of these metabolites in the region of epileptic seizures, immediately following seizures and associated with particular medical and surgical treatment interventions. Methods: Seven experiments were performed in this thesis. In all seven studies the findings in the patient groups were compared against results from an acquired control group made up of healthy volunteers. In the first experiment [3.1] twenty patients with temporal lobe epilepsy, with (10), and without hippocampal sclerosis were studied using multi voxel magnetic resonance spectroscopic imaging (MRSI) sequences in order to examine for differences in the obtained metabolites N acetyl aspartate (NAA), creatine plus phosphocreatine (Cr), choline containing compounds (Cho), GLX and myo-inositol (Ins) across the pathological groups and against a control population. In experiments [3.2], [3.3], [3.4] and [3.6] an MRS protocol that incorporated a double quantum filter acquisition sequence was applied in order to allow measurement of GABA+ (a combined measure of GABA plus homocarnosine) in addition to measurement of the metabolites examined in [3.1]. Studies were performed in the occipital lobes in patients with idiopathic generalised epilepsy (IGE) (n =10) or occipital lobe epilepsy (n = 10) [3.2], in the frontal lobes in patients with IGE (n = 21) and within regions of the MRI visible pathology in patients with large focal malformations of cortical development (MCD, n =10) [3.4]. In the last experiment using this technique patients with hippocampal sclerosis and temporal lobe epilepsy (n = 16) were studied in the ipsilateral and also in the contralateral temporal lobes and following temporal lobe surgery (n = 10) [3.6]. In experiment [3.5] ten patients were examined whilst taking and when not taking sodium valproate in order to further examine for an effect of this medication on the measured metabolite concentrations. In experiment [3.7] ten patients were studied immediately after an epileptic seizure and then again during a subsequent inter-ictal period in order to examine for an influence of the recent seizure on the measured concentrations of the main metabolites. Results: MRSI in the temporal lobes in patients with temporal lobe epilepsy identified low NAA in the anterior hippocampus that was most severe in those patients with hippocampal sclerosis. GLX elevation was a feature in the patients without hippocampal sclerosis. Metabolic abnormality was most marked in the anterior compared to the posterior hippocampal regions. GABA+ levels were elevated in patients with MCD and in the ipsilateral temporal lobe in temporal lobe epilepsy associated with hippocampal sclerosis but levels were not altered in patients with IGE or OLE. GLX was also elevated in MCD in the region of MRI visible abnormality and in IGE patients when measured in the frontal lobes. Low NAA was a feature of TLE and MCD. Patients with IGE showed normal NAA levels in the occipital lobes but reduced frontal lobe concentrations. Cr concentrations were abnormal in the immediate post ictal period but normalised within 120 minutes. NAA was not altered and no significant change in lactate concentrations was observed. Finally sodium valproate treatment was associated with a reduction in the levels of Ins and with unchanged NAA and GLX levels. Main Conclusions: MRS techniques demonstrate metabolite abnormalities in epileptic patients. NAA is the most sensitive metabolite marker of chronic pathology but levels are insensitive to recent seizure history. These findings repeat earlier observations of the usefulness of NAA measurement in the assessment of chronic epilepsy whilst illustrating ongoing uncertainty as to the correct patho-physiological interpretation of reduced NAA levels. Measurable changes in the combined Cr signal are detectable whilst elevated lactate is not reliably observed following brief epileptic seizures at 1.5T. This finding indicates a potential role for MRS in functional activation studies. Malformations of cortical development have abnormal levels of both GABA+ and GLX and MCD sub-types may well demonstrate different metabolite profiles. This finding suggests that MRS could be a useful tool in the MRI classification of MCD and in the pre-surgical assessment of patients with focal malformations. Following successful temporal lobe surgery levels of NAA remain unchanged but NAA/Cr levels appear to normalise in the contralateral temporal lobe. NAA and GLX/NAA levels were altered in the frontal lobes but not in the occipital lobes in Idiopathic Generalised Epilepsy. This finding provides imaging support for frontal lobe dysfunction as a cause or consequence of IGE. Metabolite levels are affected by administered antiepileptic drugs. Sodium valproate reduces the levels of MRS visible Ins levels whilst topiramate and gabapentin appear to be associated with higher GABA+ levels. These findings may be of major importance in the assessment of treatment effect or in the investigation of patients with possible drug resistance. The effect of valproate on Ins levels may become particularly interesting in the light of a growing understanding of the role of astrocyte dysfunction in a range of neurological conditions which include migraine, epilepsy, Alzheimer’s disease, motor neurone disease and in ischaemic lesions.

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Guedj, Eric. "Etude par IRM fonctionnelle et TEP métabolique des réorganisations mnésiques dans l'épilepsie temporale." Thesis, Aix-Marseille 2, 2010. http://www.theses.fr/2010AIX20696/document.

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L’objectif général de ce travail de thèse a été de caractériser in vivo, chez l’Homme, les réorganisations mnésiques retrouvées dans l’épilepsie temporo-mésiale pharmaco-résistante.Nous nous sommes appuyés sur une approche multimodale d’imagerie combinant étude de la connectivité et des réseaux d’activations mnésiques en IRMf, et étude de la consommation métabolique régionale inter-critique de glucose en TEP. Il s’agissait, notamment, de mieux comprendre la relative préservation mnésique retrouvée chez certains de ces patients, malgré l’implication du cortex temporal interne au sein de leurs réseaux épileptiques.Nos résultats, obtenus pour l’encodage d’items uniques non matériel-spécifiques, apportent des connaissances nouvelles sur l’adaptation fonctionnelle des réseaux cognitifs au sein et en dehors de la zone épileptogène, expliquant les différences de performance mnésique en reconnaissance, et leur lien possible avec les réseaux épileptiques.Ces travaux suggèrent, notamment, l’existence de ressources fonctionnelles additionnelles efficaces, à la fois locales et à distance, impliquant la voie visuelle ventrale bilatérale. Ces processus de compensation pourraient être conditionnés par les caractéristiques propres de l’atteinte primitive, et en particulier une implication différente des structures temporales internes au sein de la zone épileptogène. L’altération fonctionnelle de ce système perceptivo-mnésique pourrait induire une réorganisation inefficace plus large, sollicitant l’activation alternative des réseaux de l’attention, au niveau des régions fronto-cingulaires et pariétales
The overall objective of this thesis was to characterize in vivo the human memory reorganization observed in medial temporal lobe epilepsy, in particular for recognition memory.We conducted a multimodal neuroimaging approach, combining the study of connectivity and memory activation networks with fMRI, and the study of inter-ictal cerebral metabolic rate of glucose with PET. We aimed to better understand the relative preservation of memory found in some patients, despite the involvement of the medial temporal lobe within their epileptic networks. Our findings, obtained for the encoding of non material-specific single items, provide new insights into the functional adaptation of cognitive networks, within and outside the epileptogenic zone, and help to explain the differences in recognition performance, and their possible relationship with epileptic networks. These studies suggest, in particular, the existence of local and remote compensatory mechanisms which are functionally effective and involve the ventral visual stream bilaterally. These could be influenced by the exact involvement of medial temporal structures within the epileptogenic zone. The impairment of this perceptive-memory system may lead to a more large-scale reorganization with the alternative activation of an inefficient network of attention-related areas involving fronto-cingulate and parietal cortices

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Bettus, Gaëlle. "Connectivité fonctionnelle interictale dans les épilepsies du lobe temporal : étude par SEEG et IRMf au repos." Thesis, Aix-Marseille 2, 2010. http://www.theses.fr/2010AIX20655/document.

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Le but de ce travail de thèse a été de caractériser in vivo chez l’Homme, la connectivité cérébrale sur son versant fonctionnel, par le biais de deux techniques: la stéréoélectroencéphalographie (SEEG) et l’IRM fonctionnelle (IRMf) de repos. Ces travaux se sont intégrés dans le cadre du bilan préchirurgical des épilepsies du lobe temporal pharmacorésistantes, dont le but est de déterminer la zone épileptogène à réséquer pour traiter ces patients. Alors que plusieurs études en électrophysiologie ont montré que durant les crises, il existait une synchronisation anormalement élevée entre les structures impliquées dans les processus épileptogènes, aucune donnée de connectivité n’était disponible en période intercritique. Pourtant, la période intercritique est le siège d’anomalies interictales enregistrées en EEG, de profonds remaniements morphologiques, et est associée à des troubles cognitifs. Nous apportons avec ce travail, grâce au recueil et au traitement de signaux SEEG et IRMf enregistrés durant la période intercritique, de nouvelles connaissances i) sur l’organisation de la connectivité fonctionnelle basale (CFB) chez les sujets sains ; ii) sur les altérations de la CFB chez des groupes de patients mais également au niveau individuel ; iii) sur le rapport entre ces anomalies de CFB et les troubles cognitifs observés chez ces patients ; iv) enfin, sur les différences et les similitudes de la CFB évaluée par SEEG et IRMf chez les mêmes sujets, ouvrant ainsi de nouvelles perspectives dans la compréhension des relations entre le signal BOLD et le signal EEG
The aim of this thesis was to characterize the Human brain functional connectivity in vivo based on signals recorded using stereoelectroencephalography (SEEG) and resting-state functional MRI (fMRI). This work was conducted during the presurgical assessment of drug resistant temporal lobe epilepsy, which aims at determining the epileptogenic zone to be removed to treat these patients. While several electrophysiological studies have shown high synchronization between structures involved in the epileptogenic process during seizure, no similar connectivity data was available during inter-critical period. However, the interictal period is characterized by spikes recorded on EEG, morphological alterations and cognitive impairment. By analyzing fMRI and SEEG signals recorded during the interictal period, this work provides new insights into, i) basal functional connectivity (BFC) organization in healthy subjects, ii) BFC alterations in patients groups but also at the individual level, iii) the relationship between these BFC abnormalities and cognitive impairment observed in these patients; iv) the differences and similarities of BFC evaluated by SEEG and fMRI in the same subjects, thus opening up new perspectives in better understanding of relationships between BOLD and SEEG signal coupling

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Lu, Wenmiao. "Off-resonance correction in magnetic resonance imaging /." May be available electronically:, 2008. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.

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Manners, David Neil. "Magnetic resonance imaging and magnetic resonance spectroscopy of skeletal muscle." Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.269250.

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Dissertations / Theses on the topic 'Epilepsy Magnetic Resonance Imaging'

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