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Wong, Eddy Yu Ping. "Optimization of Micro Antennas for Interventional / Intravascular MRI." online version, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=case1117225501.
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Patil, Sunil. "Passive tracking and system interfaces for interventional MRI /." [S.l.] : [s.n.], 2009. http://edoc.unibas.ch/diss/DissB_8742.
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Daga, P. "Towards efficient neurosurgery : image analysis for interventional MRI." Thesis, University College London (University of London), 2014. http://discovery.ucl.ac.uk/1449559/.
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Interventional magnetic resonance imaging (iMRI) is being increasingly used for performing imageguided neurosurgical procedures. Intermittent imaging through iMRI can help a neurosurgeon visualise the target and eloquent brain areas during neurosurgery and lead to better patient outcome. MRI plays an important role in planning and performing neurosurgical procedures because it can provide highresolution anatomical images that can be used to discriminate between healthy and diseased tissue, as well as identify location and extent of functional areas. This is of significant clinical utility as it helps the surgeons maximise target resection and avoid damage to functionally important brain areas. There is clinical interest in propagating the pre-operative surgical information to the intra-operative image space as this allows the surgeons to utilise the pre-operatively generated surgical plans during surgery. The current state of the art neuronavigation systems achieve this by performing rigid registration of pre-operative and intra-operative images. As the brain undergoes non-linear deformations after craniotomy (brain shift), the rigidly registered pre-operative images do not accurately align anymore with the intra-operative images acquired during surgery. This limits the accuracy of these neuronavigation systems and hampers the surgeon’s ability to perform more aggressive interventions. In addition, intra-operative images are typically of lower quality with susceptibility artefacts inducing severe geometric and intensity distortions around areas of resection in echo planar MRI images, significantly reducing their utility in the intraoperative setting. This thesis focuses on development of novel methods for an image processing workflow that aims to maximise the utility of iMRI in neurosurgery. I present a fast, non-rigid registration algorithm that can leverage information from both structural and diffusion weighted MRI images to localise target lesions and a critical white matter tract, the optic radiation, during surgical management of temporal lobe epilepsy. A novel method for correcting susceptibility artefacts in echo planar MRI images is also developed, which combines fieldmap and image registration based correction techniques. The work developed in this thesis has been validated and successfully integrated into the surgical workflow at the National Hospital for Neurology and Neurosurgery in London and is being clinically used to inform surgical decisions.
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Carvalho, Paulo A. "Advancing Technologies for Interventional MRI Robotics with Clinical Applications." Digital WPI, 2019. https://digitalcommons.wpi.edu/etd-dissertations/577.
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An MRI’s superior soft tissue contrast and ability to perform parametric scanning make it a powerful tool for use during medical procedures; from surgery to rehabilitation. However, the MRI’s strong static magnetic field, fast switching gradients and constrained space make accomplishing procedures within it difficult. Recent advances in the field of robotics have enabled the creation of devices capable of assisting medical practitioners in this environment. In this work, technologies to enable the use and control of robotic assistive devices for MRI interventions are presented. This includes a modular controller that is designed, built and used to control two surgical systems with minimal effect on image quality. Progressive improvements to an MRI conditional actuator including the construction of a first of a kind plastic piezoelectric resonant motor stator that improves the motor’s compatibility with the MRI is presented. Finally, control algorithms are evaluated for real-time functional MRI based control of a rehabilitation robot which includes the use of a robot for controlling brain activity of a subject in an online experiment.
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Carvalho, Paulo A. "Advancing Technologies for Interventional MRI Robotics with Clinical Applications." Digital WPI, 2020. https://digitalcommons.wpi.edu/etd-dissertations/616.
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An MRI’s superior soft tissue contrast and ability to perform parametric scanning make it a powerful tool for use during medical procedures; from surgery to rehabilitation. However, the MRI’s strong static magnetic field, fast switching gradients and constrained space make accomplishing procedures within it difficult. Recent advances in the field of robotics have enabled the creation of devices capable of assisting medical practitioners in this environment. In this work, technologies to enable the use and control of robotic assistive devices for MRI interventions are presented. This includes a modular controller that is designed, built and used to control two surgical systems with minimal effect on image quality. Progressive improvements to an MRI conditional actuator including the construction of a first of a kind plastic piezoelectric resonant motor stator that improves the motor’s compatibility with the MRI is presented. Finally, control algorithms are evaluated for real-time functional MRI based control of a rehabilitation robot which includes the use of a robot for controlling brain activity of a subject in an online experiment.
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Breen, Michael Scott. "TISSUE RESPONSE TO INTERVENTIONAL MRI-GUIDED THERMAL ABLATION THERAPY." Case Western Reserve University School of Graduate Studies / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=case1080938405.
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Saikus, Christina Elena. "Towards mri-guided cardiovascular interventions." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/44912.
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Imaging guidance may allow minimally invasive alternatives to open surgical exposure and help reduce procedure risk and morbidity. The inherent vascular and soft-tissue contrast of MRI make it an appealing imaging modality to guide cardiovascular interventional procedures. Advances in real-time MRI have made MRI-guided procedures a realistic possibility. The MR environment, however, introduces additional challenges to the development of compatible, conspicuous and safe devices. The overall goal of this work was to enable selected MRI-guided cardiovascular interventional procedures with clearly visible MR devices. In the first part of this work, we developed actively visualized devices for three distinct MRI-guided interventional procedures and techniques to assess their signal performance. We then investigated factors influencing complex device safety in the MR environment and evaluated a technique to better determine and monitor potential device heating. This input contributed to the development of a system to further improve device safety with continual device monitoring and dynamic scanner feedback control. In the final part of this work, we demonstrated the utility of MRI guidance and actively visualized devices to enable traditional and complex cardiovascular access. Together these provide important elements to bring MRI-guided cardiovascular interventional procedures closer to clinical implementation.
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Elgort, Daniel Robert. "Real-Time Catheter Tracking and Adaptive Imaging for Interventional Cardiovascular MRI." Case Western Reserve University School of Graduate Studies / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=case1111437062.
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Ahluwalia, Vishwadeep. "Optimization of Functional MRI methods for olfactory interventional studies at 3T." VCU Scholars Compass, 2009. http://scholarscompass.vcu.edu/etd/1953.
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Functional MRI technique is vital in investigating the effect of an intervention on cortical activation in normal and patient population. In many such investigations, block stimulation paradigms are still the preferred method of inducing brain activation during functional imaging sessions because of the high BOLD response, ease in implementation and subject compliance especially in patient population. However, effect of an intervention can be validly interpreted only after reproducibility of a detectable BOLD response evoked by the stimulation paradigm is first verified in the absence of the intervention. Detecting a large BOLD response that is also reproducible is a difficult task particularly in olfactory Functional MRI studies due to the factors such as (a) susceptibility-induced signal loss in olfactory related brain areas and (b) desensitization to odors due to prolonged odor stimulation, which is typical when block paradigms are used. Therefore, when block paradigms are used in olfactory interventional Functional MRI studies, the effect of the intervention may not be easily interpretable due to the factors mentioned above. The first task of this thesis was to select a block stimulation paradigm that would produce a large and reproducible BOLD response. It was hypothesized that a BOLD response of this nature could be produced if within-block and across-session desensitization could be minimized and further, that desensitization could be minimized by reducing the amount of odor by pulsing the odor stimulus within a block instead of providing a continuous odor throughout the block duration. Once the best paradigm was selected, the second task of the thesis was to select the best model for use in general linear model (GLM) analysis of the functional data, so that robust activation is detected in olfactory related brain areas. Finally, the third task was to apply the paradigm and model that were selected as the best among the ones tested in this thesis, to an olfactory interventional Functional MRI study investigating the effect of food (bananas) eaten to satiety on the brain activation to the odor related to that food. The methods used in this thesis to ensure valid interpretation of an interventional effect, can serve as a template for the experimental design of future interventional Functional MRI studies.
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Johal, Parminder Singh. "Tibiofemoral movement : an in vivo study of knee kinematics using 'interventional' MRI." Thesis, Imperial College London, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.440541.
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Daniels, Barret R. "Magnetic Resonance Guided Nasojejunal Feeding Tube Placement for Neonates." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439281638.
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Serano, Peter James. "Design of a Multi-Array Radio-Frequency Coil for Interventional MRI of the Female Breast." Digital WPI, 2009. https://digitalcommons.wpi.edu/etd-theses/747.
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A new method for the simulation of radio frequency (RF) coils has been developed. This method utilizes the FEM simulation package Ansoft HFSS as a base for the modeling of RF coils with complex biological loading effects. The abilities of this software have been augmented with custom MATLAB code to enable the fast prediction of lumped element values needed to properly tune and match the coil structure as well as to perform the necessary post processing of simulation data in order to quickly generate and evaluate field data of the resonating coil and compare design variations. This method was evaluated for accuracy and implemented in the re-design of an existing four channel breast coil array for clinical imaging of the female breasts. Based on the simulation results, a commercially viable printed circuit board (PCB) implementation was developed and tested in a clinical 1.5 T MR scanner. The new design allows for wide open bilateral access to the breast regions in order to accommodate various interventional procedures. The layout has also increased axillary B1 field coverage with minor penalty to the signal-to-noise ratio of the coil array, enabling high-resolution imaging over a wide field-of-view.
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Rube, Martin. "Novel tools for interventional magnetic resonance imaging." Thesis, University of Dundee, 2014. https://discovery.dundee.ac.uk/en/studentTheses/7e3feb72-0102-431f-982a-b3cdd393994e.
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Magnetic Resonance Imaging (MRI) provides unique advantages such as superior soft tissue contrast, true multiplanar imaging, variable contrast mechanisms, measurement of temperature changes, perfusion and diffusion, and no ionizing radiation. Despite considerable research efforts in the field of interventional MRI, numerous challenges remain including restricted access to the patient, high acoustic noise and a shortage of MRI-safe devices. Novel methods and devices are presented in this thesis with the primary objective of enabling effective MRI-guided interventions, particularly abdominal needle and common catheter-based endovascular interventions. Firstly, a set of MRI-safe devices (guidewires, micro guidewires, catheters and micro catheters) were developed with passive or inductively coupling resonant markers for MRI visualisation. Secondly, a method was implemented for wireless tracking and dynamic guidance of instruments. Thirdly, a framework of technologies was developed for in-room display, wireless MRI remote control and multi-user communication along with a dedicated user interface and imaging protocol. These implementations were assessed in regards to MRI-safety, performance and usability and evaluated for MRI-guided liver biopsies, balloon angioplasty procedures and also for mechanical thrombolysis. Flow phantoms, Thiel soft-embalmed human cadavers with partially re-established perfusion and a porcine model were used for in vitro, ex vivo and in vivo validation, respectively. The results demonstrate that these interventions are experimentally feasible and practical when using the presented developments: automated device tracking and equipment designed for MRI-guided interventions streamlined procedural workflow. Specifically, it was shown that fast and accurate needle placements along complex trajectories were feasible using a wireless interactive display and control device with a dedicated user interface for interventions. Moreover, safe and efficacious balloon angioplasties of the iliac artery were practical using the described framework of technologies along with a dedicated MRI protocol. Finally, it was demonstrated that these developments could be adapted and applied to MRI-guided endovascular mechanical thrombolysis of the middle cerebral artery. The technologies, described in this thesis have been shown to overcome many of the present limitations and should therefore be useful for enabling MRI-guided interventions while not further constraining the operating physician in an already complex environment. Nevertheless, it is acknowledged that many crucial issues remain to be solved in the field of iMRI and in the context of the presented research. In particular further device optimisations, improvements of the tracking implementation along with further in vivo evaluations are required before moving towards clinical evaluation. This thesis sets the groundwork for moving ahead with the eventual clinical realisation of optimised MRI-guided interventions.
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Kim, Kisoo. "Interventional MR Elastography for the monitoring of thermal ablations." Thesis, Strasbourg, 2019. https://publication-theses.unistra.fr/public/theses_doctorat/2019/Kim_Kisoo_2019_ED269.pdf.
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L'ablation thermique vise à endommager les cellules tumorales en chauffant ou en congelant le tissu tumoral. La surveillance par IRM est une technique prometteuse pour assurer la destruction des cellules tumorales tout en aidant à préserver les tissus sains environnants. L'équipe ICube a récemment proposé l'utilisation de l'élastographie RM en temps réel (MRE) et de la thermométrie RM (MRT). Cela permet de surveiller la température et les propriétés mécaniques du tissu ciblé simultanément en temps réel. Dans cette thèse de doctorat , nous avons présenté deux développements différents afin de surmonter certaines des limitations actuelles de la MRE et de la MRT interventionnelles, en termes d’extension à la couverture spatiale de la région ciblée et au développement d’une nouvelle méthode de surveillance des ablations thermiques pour tous les types de tissus mous, y compris les tissus adipeux. Ces contributions visent à améliorer la sécurité et l'efficacité de l'ablation thermique guidée par MRThermal ablation aims at damaging tumor cells by either heating or freezing tumoral tissue. MRI monitoring is a promising technique for ensuring the destruction of tumor cells while preserving the surrounding healthy tissue. Recently, the ICube team demonstrated the use of simultaneous realtime MR Elastography (MRE) and MR Thermometry (MRT). It allows monitoring temperature and mechanical properties of the targeted tissue simultaneously in realtime. In this Ph.D. thesis, we have presented two different developments in order to overcome some of the current limitations of interventional MRE and MRT, in terms of extending to the spatial coverage of the targeted region and developing a new method to monitor thermal ablations for all types of soft tissues, including fatty tissues. These contributions aim at improving the safety and efficiency of MR guided thermal ablation
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Gudino, Natalia. "Control of Intravascular Catheters Using a 3D Array of Active Steering Coils for and Interventional MRI setting." Case Western Reserve University School of Graduate Studies / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=case1216731566.
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McManigle, John E. "Three-dimensional geometric image analysis for interventional electrophysiology." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:2f36fa8e-9c64-4807-97c0-25e63398da7e.
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Improving imaging hardware, computational power, and algorithmic design are driving advances in interventional medical imaging. We lay the groundwork here for more effective use of machine learning and image registration in clinical electrophysiology. To achieve identification of atrial fibrosis using image data, we registered the electroanatomic map (EAM) data of atrial fibrillation (AF) patients undergoing pulmonary vein isolation (PVI) with MR (n = 16) or CT (n = 18) images. The relationship between image features and bipolar voltage was evaluated using single-parameter regression and random forest models. Random forest performed significantly better than regression, identifying fibrosis with area under the receiver operating characteristic curve (AUC) 0.746 (MR) and 0.977 (CT). This is the first evaluation of voltage prediction using image data. Next, we compared the character of native atrial fibrosis with ablation scar in MR images. Fourteen AF patients undergoing repeat PVI were recruited. EAM data from their first PVI was registered to the MR images acquired before the first PVI (‘pre-operative’) and before the second PVI ('post-operative' with respect to the first PVI). Non-ablation map points had similar characteristics in the two images, while ablation points exhibited higher intensity and more heterogeneity in post-operative images. Ablation scar is more strongly enhancing and more heterogeneous than native fibrosis. Finally, we addressed myocardial measurement in 3-D echocardiograms. The circular Hough transform was modified with a feature asymmetry filter, epicardial edges, and a search constraint. Manual and Hough measurements were compared in 5641 slices from 3-D images. The enhanced Hough algorithm was more accurate than the unmodified version (Dice coefficient 0.77 vs. 0.58). This method promises utility in segmentation-assisted cross-modality registration. By improving the information that can be extracted from medical images and the ease with which that information can be accessed, this progress will contribute to the advancing integration of imaging in electrophysiology.
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深津, 博., and H. Fukatsu. "Interventional MRIの現状と将来(<特集>MRの治療応用と機器)." 日本医療機器学会, 2003. http://hdl.handle.net/2237/10862.
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Eibofner, Frank [Verfasser], and Fritz [Akademischer Betreuer] Schick. "MRI Techniques for the Visualization of Induced Magnetic Field Alterations for Cell Tracking and Interventional Procedures / Frank Eibofner ; Betreuer: Fritz Schick." Tübingen : Universitätsbibliothek Tübingen, 2015. http://d-nb.info/116339730X/34.
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Neumann, Markus. "Automatic multimodal real-time tracking for image plane alignment in interventional Magnetic Resonance Imaging." Phd thesis, Université de Strasbourg, 2014. http://tel.archives-ouvertes.fr/tel-01038023.
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Interventional magnetic resonance imaging (MRI) aims at performing minimally invasive percutaneous interventions, such as tumor ablations and biopsies, under MRI guidance. During such interventions, the acquired MR image planes are typically aligned to the surgical instrument (needle) axis and to surrounding anatomical structures of interest in order to efficiently monitor the advancement in real-time of the instrument inside the patient's body. Object tracking inside the MRI is expected to facilitate and accelerate MR-guided interventions by allowing to automatically align the image planes to the surgical instrument. In this PhD thesis, an image-based workflow is proposed and refined for automatic image plane alignment. An automatic tracking workflow was developed, performing detection and tracking of a passive marker directly in clinical real-time images. This tracking workflow is designed for fully automated image plane alignment, with minimization of tracking-dedicated time. Its main drawback is its inherent dependence on the slow clinical MRI update rate. First, the addition of motion estimation and prediction with a Kalman filter was investigated and improved the workflow tracking performance. Second, a complementary optical sensor was used for multi-sensor tracking in order to decouple the tracking update rate from the MR image acquisition rate. Performance of the workflow was evaluated with both computer simulations and experiments using an MR compatible testbed. Results show a high robustness of the multi-sensor tracking approach for dynamic image plane alignment, due to the combination of the individual strengths of each sensor.
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Júnior, Antenor Tavares de Sá. "Alterações de difusão e perfusão cerebral por RM em angioplastia carotídea com \"stent\" sob proteção cerebral por filtros." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/5/5151/tde-22022010-171639/.
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INTRODUÇÃO: A angioplastia carotídea com stent (ACS) sob proteção cerebral é opção terapêutica em pacientes com estenose carotídea. Existe o risco de embolia apesar da utilização do filtro e as modificações na perfusão cerebral após tratamento da estenose carotídea não são claras. O propósito deste estudo é avaliar, após ACS sob proteção cerebral por filtros, modificações nas seqüências de RM de difusão (DWI) e perfusão (PWI), correlacionando-as com os aspectos técnicos da ACS, com as características da estenose e com dados demográficos dos pacientes. MÉTODO: Trinta e seis pacientes portadores de estenose carotídea com idade média de 72,08 anos foram submetidos a exame de RM um dia antes e até 72 horas após a ACS com filtro de proteção. Todos os pacientes eram assintomáticos após a ACS. Áreas de restrição na DWI após a ACS foram correlacionadas com aspectos demográficos, com aspectos da técnica de angioplastia e com a presença de infartos prévios por RM. Os parâmetros CBV volume sanguíneo cerebral, MTT tempo de trânsito médio e TTP tempo para o pico são empregados para análise por PWI. RESULTADOS: Na DWI, 18 de 36 (50,00%) pacientes apresentaram novos focos (NF) de restrição na DWI após ACS. Todos os NF foram clinicamente silenciosos (100%). Estes NF eram localizados em território cerebral nutrido pela artéria carótida submetida à ACS em 77,19% e menores que 10 mm em 91,53%. Os NF em território cerebral não irrigado pela artéria carótida submetida à angioplastia correspondiam a 22,81% destes. A presença de infartos cerebrais prévios na RM foi o único fator com influência no aparecimento de NF (p=0,037). Fatores demográficos e aspectos relacionados com a técnica de angioplastia não tiveram importância na gênese dos NF. Na PWI foi observada melhora nos parâmetros temporais TTP (p<0,001) e MTT (p=0,019) quando comparados de forma normalizada em relação ao território contralateral. CONCLUSÃO: Os novos focos de restrição na DWI após ACS (NF) foram mais comuns no território ipsilateral (77,19%), no entanto houve NF no território contralateral à ACS (22,81%), possivelmente, associados ao cateterismo diagnóstico. Os NF, na sua maioria, são de pequeno diâmetro (<10 mm em 91,53%). Melhora precoce na PWI, observada nos dados normalizados, foi demonstrada nos parâmetros temporais (TTP e MTT).INTRODUCTION: Carotid angioplasty with stent (CAS) under cerebral protection is a therapeutic option in patients with carotid stenosis. There is a risk of embolism even with a filter, and changes in cerebral perfusion after treatment are not clearly understood. The purpose of this study was to evaluate changes in diffusion- (DWI) and perfusion- (PWI) weighted magnetic resonance imaging (MRI) sequences correlating them with the technical aspects of CAS, stenosis characteristics and patient demographic data. METHODS: Thirty-six carotid stenosis patients with an mean age of 72.08 years were submitted to MRI exam one day before and up to 72 hours after CAS with filter protection. All patients were asymptomatic after CAS. Areas of restriction on DWI were correlated to demographic aspects, technique of angioplasty as well the presence of previous stroke by MRI. The parameters, CBV - cerebral blood volume; MTT - mean transit time, and TTP- time to peak, are used for PWI analysis. RESULTS: Eighteen of the 36 patients (50.00%) presented new focus (NF) of restriction by DWI after CAS. All new focus were clinically silent. The NF were located in the cerebral area fed by the carotid artery submitted to CAS in 77.19% and smaller than 10mm in 91.53%. NF in cerebral area not irrigated by carotid artery submitted by angioplasty correspond to 22,81 %. The presence of previous ischemic lesion on MRI was the only factor which influenced the appearance of NF (p=0.037). Demographic factors and aspects related to angioplasty technique had no importance on NF genesis. Improvement in PWI timing parameters - TTP (p<0.001) and MTT (p=0.019) were observed in relation to the contralateral territory (normalized data). CONCLUSION: The restriction NF in the DWI after CAS are more common in the ipsilateral territory (77.19%), however there were some NF in the contralateral territory to the CAS (22.81%), possibly associated with diagnostic catheterization. Most of the NF were small in diameter (<10mm in 91.53%). Short-term improvement in PWI were demonstrated by normalized timing parameters (TTP and MTT).
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Roujol, Sébastien. "MR-guided thermotherapies of mobile organs : advances in real time correction of motion and MR-thermometry." Thesis, Bordeaux 1, 2011. http://www.theses.fr/2011BOR14263/document.
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L'ablation des tissus par hyperthermie locale guidée par IRM est une technique prometteuse pour le traitement du cancer et des arythmies cardiaques. L'IRM permet d'extraire en temps réel des informations anatomiques et thermiques des tissus. Cette thèse a pour objectif d'améliorer et d'étendre la méthodologie existante pour des interventions sur des organes mobiles comme le rein, le foie et le coeur. La première partie a été consacrée à l'introduction de l'imagerie rapide (jusqu'à 10-15 Hz) pour le guidage de l'intervention par IRM en temps réel. L'utilisation de cartes graphiques (GPGPU) a permis une accélération des calculs afin de satisfaire la contrainte de temps réel. Une précision, de l'ordre de 1°C dans les organes abdominaux et de 2-3°C dans le coeur, a été obtenue. Basé sur ces avancées, de nouveaux développements méthodologiques ont été proposés dans une seconde partie de cette thèse. L'estimation du mouvement basée sur une approche variationnelle a été améliorée pour gérer la présence de structures non persistantes et de fortes variations d'intensité dans les images. Un critère pour évaluer la qualité du mouvement estimé a été proposé et utilisé pour auto-calibrer notre algorithme d'estimation du mouvement. La méthode de correction des artefacts de thermométrie liés au mouvement, jusqu'ici restreinte aux mouvements périodiques, a été étendue à la gestion de mouvements spontanés. Enfin, un nouveau filtre temporel a été développé pour la réduction du bruit sur les cartographies de température. La procédure interventionnelle apparaît maintenant suffisamment mature pour le traitement des organes abdominaux et pour le transfert vers la clinique. Concernant le traitement des arythmies cardiaques, les méthodes ont été évaluées sur des sujets sains et dans le ventricule gauche. Par conséquent, la faisabilité de l'intervention dans les oreillettes mais aussi en présence d'arythmie devra être abordéeMR-guided thermal ablation is a promising technique for the treatment of cancer and atrial fibrillation. MRI provides both anatomical and temperature information. The objective of this thesis is to extend and improve existing techniques for such interventions in mobile organs such as the kidney, the liver and the heart. A first part of this work focuses on the use of fast MRI (up to 10-15 Hz) for guiding the intervention in real time. This study demonstrated the potential of GPGPU programming as a solution to guarantee the real time condition for both MR-reconstruction and MR-thermometry. A precision in the range of 1°C and 2-3°C was obtained in abdominal organs and in the heart, respectively. Based on these advances, new methodological developments have been carried out in a second part of this thesis. New variational approaches have proposed to address the problem of motion estimation in presence of structures appearing transient and high intensity variations in images. A novel quality criterion to assess the motion estimation is proposed and used to autocalibrate our motion estimation algorithm. The correction of motion related magnetic susceptibility variation was extended to treat the special case of spontaneous motion. Finally, a novel temporal filter is proposed to reduce the noise of MR-thermometry measurements while controlling the bias introduced by the filtering process. As a conclusion, all main obstacles for MR-guided HIFU-ablation of abdominal organs have been addressed in in-vivo and ex-vivo studies, therefore clinical studies will now be realized. However, although promising results have been obtained for MR-guided RF-ablation in the heart, its feasibility in the atrium and in presence of arrhythmia still remains to be investigated
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Chen, Xuefeng S. B. Massachusetts Institute of Technology. "Instrument guide for MRI-guided percutaneous interventions." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/59900.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 50).
As MRI guided interventions are becoming more widely practiced, the goal of this thesis was to design an instrument guidance device for MRI-guided percutaneous interventions in closed bore systems, namely cryoablation procedures where multiple probes need to be placed to treat a tumor. Multiple meetings with researchers and clinicians the Brigham and Women's Hospital were conducted to understand the challenges currently faced by interventionists, to set functional requirements for the design of a system to overcome them, and to help select a clinically viable strategy. The strategy selected involved making a device that had two degrees of angular freedom about a remote center of motion located at the probe entry point on the skin. This device is designed to be incorporated with a custom built MR coil. Structural and finite element analysis was conducted for a number of different mechanism concepts to examine their stiffness and the effect of structural displacements on the end-point probe placement accuracy. The selected concept was a curved arm piece that travels around the pivot point on a circular base, and an additional needle holder that travels along the curved arm. The sliding parts were designed with five points of constraint so that only sliding motion was possible. Thumb screws were used for preload and locking so that the probe guide could be locked along a specific trajectory. The device was prototyped via stereolithography as a proof of concept. It was found that sanding was required to fit the parts together because of overbuild in the stereolithography process. The parts functioned as designed and demonstrated that a probe could be angled about a remote pivot point. However, wear of the plastic parts eventually caused increased play between the plastic parts. Further testing and optimization of the device is planned.
by Xuefeng Chen.
S.B.
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Galassi, Francesca. "Instrument tracking and navigation for MRI-guided interventions." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/17822.
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Interventional MRI requires accurate and fast localization of medical instruments within the imaging volume of the MR scanner. Furthermore, in view of tissue motion and target dislocation, accurate intra-operative imaging is demanded. The research presented in this thesis addresses these issues with reference to a proposed MRI-guided transrectal prostate biopsy system. As the instrument is not visible in the MR images, RF fiducial markers embedded within the instrument are used to determine its pose. A novel localization method to compute the location of N fiducial markers using 1D projections is presented. The method is shown to yield significant improvements over previously proposed methods. Computational complexity was significantly reduced by avoiding cluster analysis, while high accuracy was achieved by using a set of optimally chosen projections and by applying Gaussian interpolation in peak detection. The method was analyzed and validated using a combination of experiments and Monte Carlo simulations. Experiments in 1.5 T and 2.9 T MR scanners involved both water phantoms and volunteer subjects. High robustness and sub-pixel accuracy were demonstrated while the computational time showed an improvement of up to a factor of 100 over existing solutions. This method was employed as the basis for tracking the endorectal probe during the prostate biopsy procedure. The probe was positioned by means of a remotely actuated manipulator. Miniature semiactive markers were embedded within the probe in a rigid known geometrical configuration and tracked by means of the localization method. At each position, Least-Squares fitting of the probe model with the localized one was performed in order to achieve more accurate tracking. Navigation of the probe and biopsy needle was realized through a dedicated graphical user interface. This interface displayed interpolated cross sections through the MR imaging volume and simplified graphical models of the instruments overlaid on the anatomy. Visual guidance was further improved by filtering of the markers' positions, which was enabled by the high tracking rate. In order to improve intra-operative imaging a novel external receiver array was designed and a prototype was built, as an alternative to the more conventional endorectal and pelvic receivers. This new array coil was optimized for imaging of the prostatic area for a patient in the prone position by combining a buttery coil and three single trapezoidal loops. The design is suitable for positioning the endorectal probe and does not introduce any spatial limitation to the range of movements. Experiments in a 1.5 T MR scanner and simulations demonstrated higher receiver sensitivity and homogeneity than conventional coils and also a significantly improved signal-to-noise ratio.
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Tzifa, Aphrodite. "MRI-guided or assisted interventions for congenital heart disease." Thesis, King's College London (University of London), 2013. https://kclpure.kcl.ac.uk/portal/en/theses/mriguided-or-assisted-interventions-for-congenital-heart-disease(24bf0db5-6737-4bcd-94d7-ec3bb9704fda).html.
Full textAbstract:
Congenital heart disease occurs in 0.8-1% of children. A proportion of these patients will require interventional treatment in the form of cardiac catheterisation or surgery, whilst some will only require medical therapy. Echocardiography is the investigation of choice for diagnosis and follow-up of these patients, whilst magnetic resonance imaging (MRI) is now increasingly used in most centres to assess complex congenital cases and to answer specific questions, not possible to address with echocardiography. The ability to obtain anatomical together with quantitative physiological information, such as cardiac function and flows in one examination has led to more detailed assessment and analysis of congenital heart defects and continues to improve our understanding about congenital heart disease and its treatment options. Cardiac MRI scans have now mostly replaced cardiac catheterisation procedures, routinely performed up to a few years ago to aid diagnosis. In parallel, a new form of hybrid catheterisation has emerged by combining MRI with simultaneous pressure measurement in different cardiac chambers and vascular structures. The combination of X-Ray and MRI guided (XMR) catheterisations can address clinical questions, such as estimation of pulmonary vascular resistance and cardiac output response to stress accurately, without the limitation of haemodynamic assumptions during calculations. Further to more accurate physiological information, XMR catheterisation can also offer detailed anatomical information of structures not well seen on echocardiography or MRI alone, and most importantly limit or eliminate the radiation exposure to patient that have been repetitively exposed to X-Ray radiation. The purpose of the research work presented was two-fold: a. to extend the potentials of XMR-guided cardiac catheterisations, particularly in the area of pre-operative and post-interventional evaluation of congenital heart disease and b. to advance our already established programme of solely MR-guided diagnostic cardiac catheterisations in order to materialise the first-in-man solely MR-guided therapeutic cardiac catheterisations. In this way, transcatheter interventional procedures were aimed to be performed in the MR scanner in a similar fashion and with similar equipment to the ones used in the traditional catheterisation suite, without the exposure to ionising radiation. The work towards materialisation of this idea and the world-first clinical trial on solely MRI-guided cardiac interventions for congenital heart disease are being presented in this thesis.
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Patel, Niravkumar Amrutlal. "Towards Closed-loop, Robot Assisted Percutaneous Interventions under MRI Guidance." Digital WPI, 2017. https://digitalcommons.wpi.edu/etd-dissertations/130.
Full textAbstract:
Image guided therapy procedures under MRI guidance has been a focused research area over past decade. Also, over the last decade, various MRI guided robotic devices have been developed and used clinically for percutaneous interventions, such as prostate biopsy, brachytherapy, and tissue ablation. Though MRI provides better soft tissue contrast compared to Computed Tomography and Ultrasound, it poses various challenges like constrained space, less ergonomic patient access and limited material choices due to its high magnetic field. Even after, advancements in MRI compatible actuation methods and robotic devices using them, most MRI guided interventions are still open-loop in nature and relies on preoperative or intraoperative images. In this thesis, an intraoperative MRI guided robotic system for prostate biopsy comprising of an MRI compatible 4-DOF robotic manipulator, robot controller and control application with Clinical User Interface (CUI) and surgical planning applications (3DSlicer and RadVision) is presented. This system utilizes intraoperative images acquired after each full or partial needle insertion for needle tip localization. Presented system was approved by Institutional Review Board at Brigham and Women's Hospital(BWH) and has been used in 30 patient trials. Successful translation of such a system utilizing intraoperative MR images motivated towards the development of a system architecture for close-loop, real-time MRI guided percutaneous interventions. Robot assisted, close-loop intervention could help in accurate positioning and localization of the therapy delivery instrument, improve physician and patient comfort and allow real-time therapy monitoring. Also, utilizing real-time MR images could allow correction of surgical instrument trajectory and controlled therapy delivery. Two of the applications validating the presented architecture; closed-loop needle steering and MRI guided brain tumor ablation are demonstrated under real-time MRI guidance.
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Li, Gang. "Robotic System Development for Precision MRI-Guided Needle-Based Interventions." Digital WPI, 2016. https://digitalcommons.wpi.edu/etd-dissertations/341.
Full textAbstract:
"This dissertation describes the development of a methodology for implementing robotic systems for interventional procedures under intraoperative Magnetic Resonance Imaging (MRI) guidance. MRI is an ideal imaging modality for surgical guidance of diagnostic and therapeutic procedures, thanks to its ability to perform high resolution, real-time, and high soft tissue contrast imaging without ionizing radiation. However, the strong magnetic field and sensitivity to radio frequency signals, as well as tightly confined scanner bore render great challenges to developing robotic systems within MRI environment. Discussed are potential solutions to address engineering topics related to development of MRI-compatible electro-mechanical systems and modeling of steerable needle interventions. A robotic framework is developed based on a modular design approach, supporting varying MRI-guided interventional procedures, with stereotactic neurosurgery and prostate cancer therapy as two driving exemplary applications. A piezoelectrically actuated electro-mechanical system is designed to provide precise needle placement in the bore of the scanner under interactive MRI-guidance, while overcoming the challenges inherent to MRI-guided procedures. This work presents the development of the robotic system in the aspects of requirements definition, clinical work flow development, mechanism optimization, control system design and experimental evaluation. A steerable needle is beneficial for interventional procedures with its capability to produce curved path, avoiding anatomical obstacles or compensating for needle placement errors. Two kinds of steerable needles are discussed, i.e. asymmetric-tip needle and concentric-tube cannula. A novel Gaussian-based ContinUous Rotation and Variable-curvature (CURV) model is proposed to steer asymmetric-tip needle, which enables variable curvature of the needle trajectory with independent control of needle rotation and insertion. While concentric-tube cannula is suitable for clinical applications where a curved trajectory is needed without relying on tissue interaction force. This dissertation addresses fundamental challenges in developing and deploying MRI-compatible robotic systems, and enables the technologies for MRI-guided needle-based interventions. This study applied and evaluated these techniques to a system for prostate biopsy that is currently in clinical trials, developed a neurosurgery robot prototype for interstitial thermal therapy of brain cancer under MRI guidance, and demonstrated needle steering using both asymmetric tip and pre-bent concentric-tube cannula approaches on a testbed."
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Fairhurst, Merle. "Dissecting the pain experience using psychological intervention and functional MRI." Thesis, University of Oxford, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.496874.
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Elhawary, Haytham. "MRI compatible mechatronic devices to aid medical diagnosis and intervention." Thesis, Imperial College London, 2008. http://hdl.handle.net/10044/1/11321.
Full textAbstract:
The excellent soft tissue contrast of Magnetic Resonance Imaging (MRI) makes it an invaluable tool for guiding and monitoring interventional procedures. This has encouraged the development of MR compatible manipulators capable of combining the high precision and repeatability of robotic systems with the image capabilities of MRI. A system capable of performing transrectal prostate biopsy inside a high field 1.5T MRI scanner was developed to improve the pathological diagnosis of prostate cancer. The 5 DOF device is actuated using piezoceramic motors and can position an endorectal probe inside of the rectum in order to align a biopsy needle to a target position in the prostate. A specially developed MR pulse sequence was capable of tracking two passive fiducials in the head of the endorectal probe, and could thus update the image scan planes to always include the biopsy needle. Phantom tests demonstrate the needle target accuracy was always within the \pm3mm limit specified in the requirements. A preliminary clinical trial has been performed with the manipulator showing a very successful outcome. A second system developed was able to position limbs at a desired orientation within the confined space of a closed bore scanner in order to exploit the magic angle effect to aid diagnosis of tendinous and other muskoloskeletal injury. The 3 DOF device can position tendons in the hand, knee and ankle, proving to be very versatile. The system kinematics were derived such that the device can locate the target tissue as close as possible to the isocentre, while avoiding collision between the patient anatomy and the scanner bore. Preliminary clinical trials with healthy volunteers were performed, where the signal at the Achilles tendon was measured as a function of orientation, showing clear magic angle effects in accordance with the theory.
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Bove, Christopher. "Constrained Motion Planning System for MRI-Guided, Needle-Based, Robotic Interventions." Digital WPI, 2018. https://digitalcommons.wpi.edu/etd-theses/310.
Full textAbstract:
In needle-based surgical interventions, accurate alignment and insertion of the tool is paramount for providing proper treatment at a target site while minimizing healthy tissue damage. While manually-aligned interventions are well-established, robotics platforms promise to reduce procedure time, increase precision, and improve patient comfort and survival rates. Conducting interventions in an MRI scanner can provide real-time, closed-loop feedback for a robotics platform, improving its accuracy, yet the tight environment potentially impairs motion, and perceiving this limitation when planning a procedure can be challenging. This project developed a surgical workflow and software system for evaluating the workspace and planning the motions of a robotics platform within the confines of an MRI scanner. 3D Slicer, a medical imaging visualization and processing platform, provided a familiar and intuitive interface for operators to quickly plan procedures with the robotics platform over OpenIGTLink. Robotics tools such as ROS and MoveIt! were utilized to analyze the workspace of the robot within the patient and formulate the motion planning solution for positioning of the robot during surgical procedures. For this study, a 7 DOF robot arm designed for ultrasonic ablation of brain tumors was the targeted platform. The realized system successfully yielded prototype capabilities on the neurobot for conducting workspace analysis and motion planning, integrated systems using OpenIGTLink, provided an opportunity to evaluate current software packages, and informed future work towards production-grade medical software for MRI-guided, needle-based robotic interventions.
30
Ji, Wenzhi. "Reconfigurable Fiducial-Integrated Modular Needle Driver For MRI-Guided Percutaneous Interventions." Digital WPI, 2013. https://digitalcommons.wpi.edu/etd-theses/303.
Full textAbstract:
Needle-based interventions are pervasive in Minimally Invasive Surgery (MIS), and are often used in a number of diagnostic and therapeutic procedures, including biopsy and brachytherapy seed placement. Magnetic Resonance Imaging (MRI) which can provide high quality, real time and high soft tissue contrast imaging, is an ideal guidance tool for image-guided therapy (IGT). Therefore, a MRI-guided needle-based surgical robot proves to have great potential in the application of percutaneous interventions. Presented here is the design of reconfigurable fiducial-integrated modular needle driver for MRI-guided percutaneous interventions. Further, an MRI-compatible hardware control system has been developed and enhanced to drive piezoelectric ultrasonic motors for a previously developed base robot designed to support the modular needle driver. A further contribution is the development of a fiber optic sensing system to detect robot position and joint limits. A transformer printed circuit board (PCB) and an interface board with integrated fiber optic limit sensing have been developed and tested to integrate the robot with the piezoelectric actuator control system designed by AIM Lab for closed loop control of ultrasonic Shinsei motors. A series of experiments were performed to evaluate the feasibility and accuracy of the modular needle driver. Bench top tests were conducted to validate the transformer board, fiber optic limit sensing and interface board in a lab environment. Finally, the whole robot control system was tested inside the MRI room to evaluate its MRI compatibility and stability.
31
Cole, Gregory. "Modular MRI Guided Device Development System: Development, Validation and Applications." Digital WPI, 2013. https://digitalcommons.wpi.edu/etd-dissertations/91.
Full textAbstract:
Since the first robotic surgical intervention was performed in 1985 using a PUMA industrial manipulator, development in the field of surgical robotics has been relatively fast paced, despite the tremendous costs involved in developing new robotic interventional devices. This is due to the clear advantages to augmented a clinicians skill and dexterity with the precision and reliability of computer controlled motion. A natural extension of robotic surgical intervention is the integration of image guided interventions, which give the promise of reduced trauma, procedure time and inaccuracies. Despite magnetic resonance imaging (MRI) being one of the most effective imaging modalities for visualizing soft tissue structures within the body, MRI guided surgical robotics has been frustrated by the high magnetic field in the MRI image space and the extreme sensitivity to electromagnetic interference. The primary contributions of this dissertation relate to enabling the use of direct, live MR imaging to guide and assist interventional procedures. These are the two focus areas: creation both of an integrated MRI-guided development platform and of a stereotactic neural intervention system. The integrated series of modules of the development platform represent a significant advancement in the practice of creating MRI guided mechatronic devices, as well as an understanding of design requirements for creating actuated devices to operate within a diagnostic MRI. This knowledge was gained through a systematic approach to understanding, isolating, characterizing, and circumventing difficulties associated with developing MRI-guided interventional systems. These contributions have been validated on the levels of the individual modules, the total development system, and several deployed interventional devices. An overview of this work is presented with a summary of contributions and lessons learned along the way.
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Fernandez-Gutierrez, Fabiola. "Workflow analysis, modelling and simulation for improving conventional and MRI-guided vascular interventions." Thesis, University of Dundee, 2014. https://discovery.dundee.ac.uk/en/studentTheses/6b7fca49-19ba-47b0-831a-ca9677084a7a.
Full textAbstract:
This thesis proposes a multidirectional methodological framework for a comprehensive ergonomic analysis and modelling of workflow for multi-modal vascular image-guided procedures (IGPs). Two approaches are employed to analyse the workflow: Discrete Event Simulation (DES) and purpose-oriented physical models. In contrast to previous studies, the proposed methodology looks in detail the actions carried out within the intervention rooms and the clinical experience during the procedures with three main objectives: to provide a deeper understanding of vascular procedures, to predict the impact of protocol modifications and to offer a framework to develop new image-guided protocols for the alternative use of Magnetic Resonance (MR) imaging in comparison with X-Ray Digital Subtraction Angiography (DSA). The methodological framework includes an assessment of commercial simulation software packages to evaluate their fitness to the specific requirements of this research. The novel methodology is applied to several cases studies of common vascular IGPs. In addition, a case of MR – guided focused ultrasound intervention demonstrates how it is possible to extend the framework to study non-vascular IGPs. The multi-disciplinary methodological framework described opens a new way to understand IGPs that could be used in prospective applications such as medical education and medical devices regulations.
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Mewes, André [Verfasser], and Christian [Gutachter] Hansen. "Projector-based augmented reality and touchless interaction to support MRI-guided interventions / André Mewes ; Gutachter: Christian Hansen." Magdeburg : Universitätsbibliothek Otto-von-Guericke-Universität, 2019. http://d-nb.info/1219965804/34.
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Wartenberg, Marek. "Towards Hands-On Cooperative Control for Closed-Loop MRI-Guided Targeted Prostate Biopsy." Digital WPI, 2018. https://digitalcommons.wpi.edu/etd-dissertations/94.
Full textAbstract:
Intra-operative imaging is sometimes available to assist in needle biopsy, but typical open- loop insertion does not account for unmodeled needle deflection or target shift. Robotic closed-loop compensation for deviation from an initial straight-line trajectory can reduce the targeting error, using image-guidance for rotational control of an asymmetric bevel tip. By pairing closed-loop trajectory compensation with a hands-on cooperatively controlled needle insertion, a physician's control of the procedure can be maintained while incorporating benefits of robotic accuracy. Additionally, if puncture of a membrane can be detected, an enhanced haptic response can assist the physician in perceived anatomical localization of the needle tip. Functionality was implemented on a needle placement robot suitable for use in the MR environment and capable of holding a typical clinically used biopsy gun. The robot is configured for cooperatively controlled needle insertion with continuous closed-loop image- guided needle rotation. The robot and custom controller were tested for their effect on the Signal-to-Noise ratio (SNR) of MR images, and the results showed an approximate drop of only 12% in signal when the robot was present, and no additional signal drop when the robot was powered on or moving. The hardware and software subsystems were developed for clinical translation, and after each was validated in the lab they were integrated into the clinical environment to mimic the workflow of MRI-guided targeted biopsy. The full system was evaluated in-bore at Brigham and Women’s Hospital in Boston, MA where experiments for real-time puncture detection and MR image-guided targeted needle insertions under cooperative control were performed. Results showed overall targeting accuracy was 3.42mm RMS, improving accuracy by approximately 50% as compared to clinical trials of prostate biopsy using manual needle insertion. A cooperatively controlled robotic biopsy is more likely to gain acceptance by physicians over teleoperation due to maintaining proximity to the surgical site, but regulatory hurdles regarding robotic needle insertion still exist. The current robotic system framework is suitable for clinical use as it was fully validated in-bore, but some modifications could be made to increase the likelihood of regulatory approval. With these modifications the system could be ready for cadaver and pre- clinical animal trials within one year, and ready for in-human clinical trials in the next two to three years.
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Su, Hao. "Force Sensing and Teleoperation of Continuum Robot for MRI-Guided Surgery." Digital WPI, 2013. https://digitalcommons.wpi.edu/etd-dissertations/156.
Full textAbstract:
Percutaneous needle placement, a minimally invasive procedure performed dozens of millions in the U.S. each year, relies on dedicated skill and long-term training due to difficult control of needle trajectory inside tissue and mental registration of images to locations inside the patient. Inaccurate needle placement may miss cancer tumors during diagnosis or eradicate healthy tissue during therapy. MRI provides ideal procedure guidance with the merit of excellent soft tissue contrast and volumetric imaging for high spatial resolution visualization of targets and surgical tool. However, manual insertion in the bore of an MRI scanner has awkward ergonomics due to difficult access to the patient, making both training and intervention even harder.
To overcome the challenges related to MRI electromagnetic compatibility and mechanical constraints of the confined close-bore, a modular networked robotic system utilizing piezoelectric actuation for fully actuated prostate biopsy and brachytherapy is developed and evaluated with accuracy study. To enhance manipulation dexterity, two kinds of steerable continuum needle robots are developed. The asymmetric tip needle robot performs needle rotation and translation control to minimize tissue deformation, and increase steering dexterity to compensate placement error under continuous MRI guidance. The MRI-guided concentric tube robot is deployed to access delicate surgical sites that are traditionally inaccessible by straight and rigid surgical tools without relying on tissue reaction force. The master-slave teleoperation system with hybrid actuation is the first of its kind for prostate intervention with force feedback. The teleoperation controller provides the feel and functionality of manual needle insertion. Fabry- Perot interferometer based fiber optic force sensor is developed for the slave manipulator to measure needle insertion force and render proprioception feedback during teleoperation.
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Leiss, Dominik. ""Hilf mir, es selbst zu tun" : Lehrerinterventionen beim mathematischen Modellieren /." Hildesheim ; Berlin : Franzbecker, 2007. http://d-nb.info/988096633/04.
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Ojala, R. (Risto). "MR-guided interventions at 0.23T:facilities, user interface, guiding technology and musculoskeletal applications." Doctoral thesis, University of Oulu, 2002. http://urn.fi/urn:isbn:9514266382.
Full textAbstract:
Abstract
Magnetic resonance imaging (MRI) has excellent soft tissue contrast,
which can be enhanced by different contrast agents, multiplanar imaging
capability and high temporal and spatial resolution. Even blood vessels
can be easily visualised, and MRI parameters are sensitive to temperature.
Therefore, MRI has the greatest potential for guiding and monitoring
interventional and surgical procedures.
The aim of this study was to design and evaluate new solutions for
MR-guided procedures and surgery, to develop the technique and to assess
the feasibility of MR-guided nerve root infiltration, bone biopsy and
sacroiliac (SI) joint arthrography.
The possibilities for versatile use of MR scanners were studied with
a setup where an MR scanner with a 0,23 T open magnet was installed in a
full-scale operating room (OR) to allow diagnostic MRI examinations,
research, radiological interventions and neurosurgical operations to be
performed in the same facility. All of the 144 MR-guided radiological
interventions and neurosurgical operations performed in Oulu University
Hospital between February 1999 and September 2000 were included in the
study. The studied setup was a functionally feasible solution for combined
neurosurgical and radiological use.
To further improve MR-guided interventions, a new user interface was
developed and preliminary tested with simulated clinical experiments. The
new user interface seemed to be easily adobted by radiologists for
interventional procedures.
MR-guided nerve root infiltrations were studied by using MRI
guidance on 34 consequent patients referred for first sacral root
infiltration. Needle placement into the first sacral nerve root sheath was
successful in 34 of the 35 (97%) cases, and the average duration of the
procedure was 32 minutes.
Bone biopsies were performed using a bone biopsy set designed in our
institution to be connected to an optical tracking system. The feasibility
of this new guiding system was evaluated with biopsies from five different
anatomical areas. The bone biopsy system was successfully applied to all
patients and provided a safe and accurate guidance method for all phases
of the procedure.
Twenty patients with low back pain suspected to arise from the SI
joint underwent MR-guided SI joint arthrography. The procedure was
successfully performed in all cases. The needle guiding with optical
tracking inside the soft tissues proved to be accurate enough for
successful procedures.
In conclusion, versatile use of MR scanners for diagnostic imaging,
radiological procedures and neurosurgery is feasible if planned properly.
The prototype of a new user interface for MR-guided procedures allows
radiologist to fully control the MR-scanner during the procedure. MRI is a
suitable and accurate guidance method for musculoskeletal interventions.
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Ma, Yunzhao. "Passive Resonant Coil Based Fast Registration And Tracking System For Real-Time Mri-Guided Minimally Invasive Surgery." Digital WPI, 2013. https://digitalcommons.wpi.edu/etd-theses/867.
Full textAbstract:
"This thesis presents a single-slice based fast stereotactic registration and tracking technique along with a corresponding modular system for guiding robotic mechanism or interventional instrument to perform needle-based interventions under live MRI guidance. The system can provide tracking of full 6 degree-of-freedom (DOF) in stereotactic interventional surgery based upon a single, rapidly acquired cross-sectional image. The whole system is constructed with a modular data transmission software framework and mechanical structure so that it supports remote supervision and manipulation between a 3D Matlab tracking user interface (UI) and an existing MRI robot controller by using the OpenIGTLink network communication protocol. It provides better closed-loop control by implementing a feedback output interface to the MRI-guided robot. A new compact fiducial frame design is presented, and the fiducial is wrapped with a passive resonant coil. The coil resonates at the Larmor frequency for 3T MRI to enhance signal strength and enable for rapid imaging. The fiducial can be attached near the distal end of the robot and coaxially with a needle so as to visualize target tissue and track the surgical tool synchronously. The MRI-compatible design of fiducial frame, robust tracking algorithm and modular interface allow this tracking system to be conveniently used on different robots or devices and in different size of MRI bores. Several iterations of the tracking fiducial and passive resonant coils were constructed and evaluated in a Phillips Achieva 3T MRI. To assess accuracy and robustness of the tracking algorithm, 25 groups of images with different poses were successively scanned along specific sequence in and MRI experiment. The translational RMS error along depth is 0.271mm with standard deviation of 0.277mm for totally 100 samples. The overall angular RMS error is less than 0.426 degree with standard deviation of 0.526 degree for totally 150 samples. The passive resonant coils were shown to significantly increase signal intensity in the fiducial relative to the surroundings and provide for rapid imaging with low flip angles. "
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Riedel, Tim. "Experimentelle und klinische Evaluation eines Navigationssystems für Interventionen an einem herkömmlichen MRT." Doctoral thesis, Universitätsbibliothek Leipzig, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-104636.
Full textAbstract:
Mit Hilfe eines kommerziellen, am Universitätsklinikum Leipzig vorhandenen
Navigationssystems (Localite) ist es möglich, Interventionen in einer herkömmlichen MRTUmgebung
unter Echtzeitnavigation durchzuführen. In der vorliegenden Arbeit werden die
Genauigkeit, Benutzerfreundlichkeit sowie der Zeitaufwand für perkutane Punktionen mit
diesem System untersucht.
Zur Navigation wird das jeweilige Instrument optisch verfolgt. Die automatische
Patientenregistrierung außerhalb des MR-Tunnels erfolgt über eine einmalige 3DLokalisation
spezieller MR-Marker. 24 Operateure mit unterschiedlicher radiologischer
Erfahrung führten insgesamt 240 unterschiedlich schwere Punktionen an einem selbst
entwickelten Phantom durch. Nach diesen Versuchen füllten die Operateure einen Fragebogen
zur Handhabbarkeit des Systems aus. Zudem wurden 24 klinische perkutane Interventionen in
nicht atemverschieblichen Körperregionen ausgewertet. Für alle Biopsien wurden Zeiten für
charakteristische Arbeitsschritte dokumentiert.
Die Treffergenauigkeit war im Phantomexperiment für alle Gruppen relativ hoch (Fachärzte:
93%, Assistenzärzte: 88%, Studenten 81%; Cochran p=0,104). Die dazugehörigen
durchschnittlichen Zeiten für einen Biopsiezyklus lagen, gemessen in Minuten, bei 4:13 (FÄ),
4:42 (AÄ) und 5:06 (MS) (P<0,001). Die subjektiven Bewertungen des Navigationssystems
an Hand der Aussagen (Items) des Fragebogens zeigten keine Abhängigkeit vom
Erfahrungsgrad des Operateurs. Die diagnostische Genauigkeit der klinischen Interventionen
lag bei 92%. Die mittlere Interventionszeit betrug dabei 18 min.
Das Navigationssystem wurde erfolgreich für Interventionen in verschiedenen
Körperregionen eingesetzt. Die Genauigkeit und die benötigten Eingriffszeiten sind mit
anderen in der Literatur beschriebenen MRT-geführten Interventionen vergleichbar. Auch
unerfahrene Operateure konnten das Navigationssystem relativ schnell und sicher anwenden.
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Schell, Jean-Baptiste. "Microsystème de positionnement dédié à l'instrumentation d'aiguilles pour intervention chirurgicale sous scanner IRM." Thesis, Strasbourg, 2013. http://www.theses.fr/2013STRAD043.
Full textAbstract:
Les interventions chirurgicales s'orientent de plus en plus vers des techniques dites mini-invasives. Dans ce mode d'intervention, le praticien perd la vision directe de l'extrémité de l'instrument médical qu'il manipule. Le contrôle visuel du déplacement de l'instrument à l'intérieur du corps humain s'effectue alors sur écran grâce aux techniques d'imagerie médicale, en particulier l'imagerie par résonance magnétique (IRM). Afin d'assurer une grande précision du déplacement de l'instrument, sa position doit être connue pour permettre un recalage automatique du plan d'imagerie en temps réel. Ce document décrit la conception et la caractérisation d'un système de positionnement fonctionnant sous IRM et pouvant s'insérer dans un instrument médical de très petit diamètre. Afin d'aboutir à des dimensions millimétriques, le système est réalisé sur une puce en silicium utilisant les procédés standard de fabrication de la micro-électronique : la technologie CMOS 0,35 µm basse tension. Ce microsystème est basé sur l'utilisation d'un capteur magnétique 3D à effet Hall associé à l'électronique intégrée spécifique au traitement du signal, permettant d'extraire la mesure précise des gradients de champ magnétique inhérents au principe même de l'IRM. La relation unique entre les coordonnées spatiales du tunnel du scanner IRM et les gradients de champ magnétique, rend possible la détermination de la position et de l'orientation du microsystème. Les résultats expérimentaux montrent qu'une localisation est possible en 3 ms avec une résolution spatiale sub-millimétriqueSurgeries are moving more and more towards so called minimally invasive techniques. With these techniques, the surgeon looses direct view of the medical tool that he manipulates. The visual control of the instrument movement inside the human body is monitored on a screen through medical imaging techniques, particularly magnetic resonance imaging (MRI). To ensure a high accuracy of the instrument movement, its position must be known to enable the automatic registration of the imaging plane in real time.This work describes the design and characterization of a positioning system operating in a MRI scanner which can be embedded in medical devices of very small diameters. To achieve millimeter dimensions, the system is realized on a silicon chip using standard manufacturing processes of microelectronics : low voltage 0.35 µm CMOS technology. This microsystem is based on the use of a 3D magnetic Hall effect sensor co-integrated with specific signal processing electronics to extract the accurately measured magnetic field gradients which are inherent to the MRI principle. The unique relationship between scanner bore space coordinates and the magnetic field gradients allows to determine the position and orientation of the microsystem. Experimental results show that localization is possible in 3 ms with sub-millimeter spatial resolution
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Favre, Pauline. "Dysfonctionnement fronto-limbique dans le trouble bipolaire et apports des interventions thérapeutiques psychosociales : approche par l'IRM multimodale." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENS027/document.
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Le trouble bipolaire (TB) est une pathologie chronique de l'humeur, caractérisée par des perturbations du fonctionnement émotionnel et cognitif lors des périodes dépressives, maniaques, et intercritiques (euthymiques). L'essor récent des interventions psychosociales spécifiques, telles que la psychoéducation, dans la prise en charge du TB est dû à une efficacité considérable démontrée dans l'optimisation de la réponse et la stabilisation clinique des patients bipolaires (BP). L'objectif de cette thèse a été d'identifier le substrat cérébral, anatomique et fonctionnel, qui sous-tend (i) les troubles cognitifs et émotionnels persistants lors des périodes euthymiques, afin de dégager des marqueurs traits de la maladie ; (ii) l'amélioration symptomatique suite à l'application d'un programme de psychoéducation chez les patients BP. Nos résultats ont montré que le TB se caractérise par une dérégulation de l'activité et de la connectivité des régions préfrontales et limbiques, respectivement impliquées dans le contrôle cognitif et la génération/perception des émotions. Nous avons également mis en évidence, à la fois au repos et lors d'une tâche cognitivo-émotionnelle, une connectivité anormale chez les patients BP entre le « default mode network », qui sous-tend des processus mentaux égocentrés, et le « task positive network », qui est impliqué dans des processus cognitifs exocentrés. Suite à trois mois de psychoéducation, les anomalies d'activation fronto-limbique chez les patients BP étaient atténuées. De plus, la diffusivité au sein du faisceau unciné, qui relie ces régions, était améliorée. En outre, l'atteinte de la structure anatomique des régions fronto-limbiques ainsi que de leurs connexions, constituait un facteur prédictif de la réponse à la psychoéducation. L'ensemble de nos résultats suggèrent que les déficits de régulation émotionnelle et de contrôle attentionnel caractérisant le TB pourraient être modulés par l'amélioration du contrôle cognitif « top-down », induit par la participation à un programme de psychoéducationBipolar disorder (BD) is a chronic mood disorder characterized by disturbances in emotional and cognitive processing during periods of depression, mania, and intercritical (euthymic) periods. Recently, the management of BD has been expanded by specific psychosocial interventions, such as psychoeducation, which showed high efficacy in improving BD symptoms. The aim of this thesis was to identify the anatomical and functional cerebral substrate related to (i) enduring cognitive and emotional impairments during euthymic periods, in order to identify trait markers of the disease; (ii) symptomatic improvement due to the participation in a psychoeducation program in BP patients. Our results showed that BD is characterized by dysregulation of the activity and the connectivity of prefrontal and limbic regions, responsible for the cognitive control and the generation/perception of emotions respectively. We also highlighted, both at rest and during a cognitive task, an abnormal cerebral connectivity between the “default mode network”, which is involved in egocentric thought processes, and the “task positive network”, which is involved in exocentric cognitive processes. After three months of psychoeducation, BD patients showed significant reduction of fronto-limbic abnormalities and better diffusivity along the uncinate fasciculus, which connects these regions. Furthermore, abnormalities of the anatomical structure of fronto-limbic regions, as well as of their connections, may be a predictor of psychoeducation outcome. We thus suggest that impairment of emotional regulation and attentional control that characterized BD could be modulated by the improvement of the “top-down” cognitive control induced by the participation in a psychoeducational program
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Wendt, Oliver. "Entwicklung einer spulenintegrierten und automatisch gesteuerten Biopsieeinrichtung zur histologischen Abklärung von Kleintumoren in der MR-Mammadiagnostik." Doctoral thesis, Humboldt-Universität zu Berlin, Medizinische Fakultät - Universitätsklinikum Charité, 2004. http://dx.doi.org/10.18452/15064.
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Brustkrebs stellt eine der am häufigsten vorkommenden Krebserkrankungen bei Frauen weltweit dar. Jährlich erkranken in Deutschland ca. 47.000 Frauen neu an Brustkrebs, ca. 18.000 fallen dieser Krankheit im gleichen Zeitraum zum Opfer. Die Brustkrebsdiagnostik basiert auf klinische und verschiedene bildgebende Methoden, die Magnetresonanztomographie (MRT) weist dabei die höchste Sensitivität speziell bei der Erkennung kleiner Tumore unter 5 mm auf. Im Hinblick auf zukünftige Verbesserungen der MR-Bildgebung wird bereits vermutet, dass im Jahr 2010 ca. 50% der neudetektierten Brustkrebse kleiner als 10 mm sein werden. Zur Erhöhung der Diagnosesicherheit werden suspekte Läsionen sowie unklare bildgestützte Befunde zusätzlich mittels Biopsie abgeklärt. In Bezug auf den Stand der Technik ist die sichere Biopsie von Tumoren unter 10 mm Größe jedoch schwierig. Mit dem Ziel, die MR-gestützte Biopsie im Hinblick auf eine höhere Effizienz und Präzision zu verbessern, wurde ein neuer Prototyp für minimal invasive Biopsien speziell in geschlossenen MR-Tomographen entwickelt. Dieses MR-kompatible System basiert auf verschiedene Neukonzeptionen, mit einem automatischen Positioniersystem und Biopsieinstrument zur Ausführung der Intervention. Die extrem hohen Anforderungen an dieses System konnten nur durch spezielle Konstruktionen und Kinematiken, sowie durch MR-kompatible Materialien, Aktoren und Sensoren gelöst werden. Das System ist modular aufgebaut und unterstützt Brustbiopsien sowohl von cranial oder caudal im direkten Anschluss an die Tumorerkennung mit einer neuen doppelseitigen MR-Brustspule. Ein großer Vorteil dieses neuen Ansatzes liegt in der hohen Präzision und der Möglichkeit, sowohl die bildgebende Diagnostik als auch die Biopsie während eines Untersuchungstermines durchzuführen. Die vorklinische Erprobung in einem 1,5 T Hochfeld-MRT zeigte, dass die Zielabweichungen des Instrumentes geringer als 1 mm waren, so dass Interventionen mit hoher Genauigkeit und Reproduzierbarkeit durchführbar wären. Das System implementiert benutzerfreundliche Oberflächen für die Interventionsplanung und für die Gerätesteuerung. Das vorliegende Dissertation stellt die Konzepte und Ergebnisse dieser neuen Biopsieeinrichtung vor und nimmt Bezug auf zahlreiche wissenschaftliche Untersuchungen, insbesondere im Hinblick auf die Anwendung von Materialien und Aktoren im MRT-Magnetfeld.Breast cancer is one of the most common cancer diseases which women suffer world wide. The incidence rate of breast cancer in Germany goes along with about 47.000 women per year, 18.000 fatal casualties were ascertained in the same period. The breast cancer diagnostic is based on clinical and different imaging methods, whereas Magnetic Resonance Imaging (MRI) is the most sensitive imaging modality in the detection of especially small lesions under 5 mm. Due to improvements of breast imaging - especially MRI - it has been predicted that by the year 2010 about 50% of newly diagnosed breast cancers will be less than 10 mm in size. However, to assure the image based breast cancer diagnosis, biopsies of tumor tissue are often necessary in order to avoid false specified results. With reference to the state of the art, it is still difficult to achieve sufficient accurate MRI-supported biopsies for tumor sizes of under 10 mm. To improve the MR-controlled diagnostic in respect of increasing the efficiency and precision of the biopsy method, a new apparatus for minimal invasive breast biopsies particularly for the use inside closed bore MRI-scanner was developed. This MR-compatible device is based on new concepts which meet the extremely high requirements on interventions in strong magnetic fields through special designs and kinematic concepts and the application of MR-compatible materials, actors and sensor systems. It is of a modular structure and consists mainly of an automated positioning unit and an integrated intervention tool. This new system makes it possible to do the breast interventions either from the cranial or the caudal position directly after tumor detecting with the use of a new double breast coil. A major advantage of this approach is the high accuracy and the possibility to realize image diagnostic and biopsy in one session. As the preclinical evaluation with a 1.5 T MRI-scanner showed, the deviation of the intervention device regarding instrument positioning to a located target was less than 1mm, so that interventions could be carried out precisely and reproducible. Furthermore there were no image interferences due to the additional materials in the MRI-isocenter. The system implements a user-interface for intervention planning on up-to-date MR images and device control. Besides the concepts and results of the new biopsy device, the present dissertation refers to numerous scientific investigations with a focus on material and actuator application in the magnetic field of a MRI-scanner.
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Yuan, Quan. "Modélisation d’anévrisme intracrânien." Thesis, Compiègne, 2018. http://www.theses.fr/2018COMP2402/document.
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Les anévrismes intracrâniens présentent des risques importants en raison de leur taux de rupture élevé et des conséquences qui peuvent être fatales comme lors d’hémorragies méningées. Afin d’effectuer une recherche hémodynamique sur l’anévrisme intracrânien in vitro, un fantôme est indispensable. Jusqu’à présent, des fantômes rigides ou simplifiés sont utilisés dans littérature, peu d’entre eux sont suffisamment fidèle à la réalité. Le travail de cette thèse se concentre sur la méthodologie de fabrication des fantômes patient-spécifiques d’anévrismes intracrâniens ainsi que leur mise en œuvre pour différentes utilisations. Ces fantômes possèdent la forme anatomique de l’artère du patient et une paroi élastique. Ils sont fabriqués en appliquant une technique originale de prototypage rapide. Les fantômes sont vérifiés selon plusieurs aspects. Pour effectuer des recherches hémodynamiques sur les fantômes, un banc d’essai compatible avec différentes modalités d’imagerie a été conçu. L’angiographie par résonance magnétique 2D par contraste de phase a été utilisée pour étudier l’hémodynamique des fantômes. Le comportement dynamique de paroi, les trajectoires 3D du flux et son champ de vélocité sont analysés. L’application potentielle dans domaine clinique du fantôme patient-spécifique a été aussi testée dans cette thèse, des simulations d’intervention sur des anévrismes intracrâniens ont été effectuées sur le banc d’essai et les fantômes, les résultats de différentes méthodes ont été analysés et comparésIntracranial aneurysms are a hazard to human health because of their high rupture rate and fatal subsequence, such as subarachnoid hemorrhage. In order to carry out a hemodynamic research in vitro on the intracranial aneurysm, a phantom is indispensable. Until now, rigid or simplified phantoms are mainly used in the literature, few among them possess sufficient properties compared with reality. The work of this thesis focuses on the methodology of manufacturing patient-specific phantoms of intracranial aneurysms as well as their implementation for different uses. The phantoms have an anatomical shape of patient’s artery and an elastic wall. They are manufactured by applying an original rapid prototyping technique. The phantoms are examined and verified in different ways. In order to perform a hemodynamic research of the phantoms, a testing platform compatible with different imaging modalities has been designed and established. 2D phase-contrast magnetic resonance angiography was applied in the hemodynamic study of the phantoms. The dynamic behavior of the artery wall, the 3D path-line of flow and the velocity field of flow were analyzed. The potential application in the clinical domain of the patient-specific phantoms was also tested in this thesis, simulations of intervention on intracranial aneurysms were carried out with the testing platform and the phantoms, the results of different treatment strategies were analyzed and compared
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LaFountain, Richard A. "Development and Application of CPX-CMR protocol for Cardiopulmonary Evaluation of Acute Exercise, Physical Training Response, and Ketogenic Diet Interventions in Healthy Humans, Athletes, and Military Personnel." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1534323074156873.
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Fazakarley, Louise. "The development and testing of a novel intervention (Mii-vitaliSe) to support people with Multiple Sclerosis to be active : a pilot evaluation." Thesis, Bournemouth University, 2018. http://eprints.bournemouth.ac.uk/31244/.
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Background: There are many benefits of physical activity for people with MS, but also barriers to participation. Active home gaming might help to maintain enthusiasm to exercise over the longer term. Pilot research in the USA suggested the WiiTM can be used safely at home by mobile people with MS. Aims: To develop and conduct preliminary testing of a home-based physiotherapist-supported WiiTM intervention (Mii-vitaliSe) for people with MS. Trial design: A mixed method study incorporating service user involvement throughout. Mii- vitaliSe (incorporates off-the-shelf WiiTM software, physiotherapist support and resource materials) was developed and piloted. Methods: A mixed methods wait-list parallel arm randomised controlled trial. Thirty ambulatory people with moderate MS were randomised to receive Mii-vitaliSe (incorporating off-the-shelf WiiTM software, physiotherapist support and resource materials) either immediately (for 12 months) or after a 6 month delay (for 6 months). Outcomes included assessments of balance, gait, mobility, hand dexterity, activity levels and adherence at baseline, 6 and 12 months. Interviews (n=25) sought participants’ experiences of taking part and physiotherapists’ (n=2) feedback. Results: Recruitment (31%), screening and data collection (97% complete data at six months) procedures worked well and participants found randomisation to a delayed group acceptable. Preliminary estimates of effect size were calculated for the outcome measures and the largest (d=0.41) positive effect found for the iTUG (instrumented Timed Up and Go). On average participants used the WiiTM twice a week for 30 minutes. Some continued to use the WiiTM for 12 months. Support and advice from the intervention resources were perceived to be helpful and a range of physical and psychological benefits reported. Conclusions: A novel intervention using the WiiTM has been developed and undergone feasibility testing. Mii-vitaliSe offers a way for people with MS to increase physical activity levels but requires further development and evaluation.
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Djabelkhir, Jemmi Leila. "Prise en charge non pharmacologique des troubles cognitifs légers : effets différentiels d'un programme de stimulation cognitive informatisée selon la sévérité des hypersignaux de la substance blanche de patients MCI." Thesis, Sorbonne Paris Cité, 2017. http://www.theses.fr/2017USPCB241.
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Les hypersignaux de la substance blanche (HSB) ont été associés à des déficits exécutifs et mnésiques et à une atteinte des circuits corticaux et sous-corticaux frontaux. Leur présence, en plus du dépôt ß-amyloïde chez de nombreux patients avec un MCI (Mild Cognitive Impairment ou trouble cognitif léger) augmenterait le risque de conversion vers une maladie d'Alzheimer (MA). Un des enjeux importants dans la phase préclinique de la maladie est d'explorer le potentiel des interventions cognitives pour prévenir le déclin cognitif et la progression vers une MA. Alors que les HSB sont de plus en plus considérés comme un des facteurs déterminant l'hétérogénéité des patients MCI, peu d'étude ont pris en compte leur présence dans les interventions cognitives. L'hypothèse qu'une intervention pourrait induire des effets différentiels selon l'existence ou non d'hypersignaux dans le MCI reste inexplorée à notre connaissance, et est au cœur de ce travail de thèseWhite matter hyper signals (WMH) were associated with executive and memory deficits and impairment of the cortical and subcortical frontal circuits. Their presence, in addition to amyloid deposition in many patients with Mild Cognitive Impairment (MCI), would increase the risk of conversion to Alzheimer's disease (AD). An important issues in the preclinical phase of MCI is to explore the potential of cognitive interventions to prevent cognitive decline and progression to AD. While WMH are increasingly considered as one of factors determining the heterogeneity of MCI patients, few studies have take into account their presence in cognitive interventions. The hypothesis that an intervention could induce differential effects according to the existence or not of WMH in MCI remains unexplored to our knowledge, and is at the heart of this work of thesis
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Canadé, Rosario Franco. "Be here now : evaluating an adapted mindfulness-based intervention in a mixed population with acquired brain injury (ABI) and neurological conditions." Thesis, University of Hertfordshire, 2014. http://hdl.handle.net/2299/14399.
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Acquired brain injury (ABI) and long-term neurological conditions (such as multiple sclerosis, Parkinson’s disease), are major causes of disability in the UK, and can lead to significant physical, cognitive, neuro-behavioural, psychological and social difficulties for sufferers. Individuals affected by an ABI or neurological conditions commonly report difficulties around emotional adjustment, reduced attention, mental control, and self-efficacy and their health-related quality of life also often appears to be much reduced. Whilst conventional neuro-rehabilitation has tended to address physical and cognitive impairments and deficits rather than psychological sequelae, recently a growing trend for more holistic approaches appears to have emerged (e.g., Wilson et al., 2000, 2013). Amongst these approaches, mindfulness-based interventions (collectively known as MBIs) have sought to address this gap in terms of therapeutic intervention. There is a growing body of research evidence pointing to the utility of MBIs in the rehabilitation and support of these populations in improving perceived quality of life and increasing self-management of these conditions. However, the research still remains limited and debate persists in terms of the conceptual and theoretical framework of mindfulness. The present study sought to evaluate the effectiveness of an adapted, short-form MBI group programme for a mixed population of patients (n = 22) currently offered in a local neuro-rehabilitation service. A specific pre-post control group design was adopted in order to investigate whether the intervention produced improvements in mindfulness skills, and whether these would in turn lead to improvements in measures associated with self-efficacy and perceived quality of life. Results indicated participants completing the MBI group programme showed significantly higher mean scores across measures of mindfulness. The results also indicated that these improvements were predictive of improvements across self-efficacy and quality of life measures, with large effect sizes observed. The findings would appear to support the research hypothesis that a suitably modified MBI is beneficial for a mixed ABI population. Findings, study limitations, clinical relevance and implications, as well as methodological and theoretical considerations and directions for future research are discussed in light of the main research questions.
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Abdelaziz, Salih. "Développement d'un système robotique pour la radiologie interventionnelle sous IRM." Phd thesis, Université de Strasbourg, 2012. http://tel.archives-ouvertes.fr/tel-00801844.
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La réalisation de gestes percutanés dans l'IRM ouvre la voie à des pratiques médicales prometteuses. En revanche, l'utilisation de l'IRM reste à ce jour limitée, et ce malgré l'intérêt en terme de qualité d'image. Cela est dû principalement à l'étroitesse du tunnel et à la complexité des gestes réalisés. Pour rendre accessibles de telles pratiques, une assistance robotique semble très pertinente. Pour le concepteur, la réalisation d'un système robotisé compatible IRM n'est pas une tâche facile, étant donné l'espace disponible et la présence d'un champ magnétique intense. C'est dans ce contexte que nous avons développé un assistant robotique, MRGuide, dédié aux traitements du cancer de la prostate dans l'IRM. Il s'agit d'un manipulateur à câbles avec un actionnement déporté. Dans ce travail, de nombreuses contributions menant à la réalisation de ce prototypes ont présentées. Parmi celles‐ci, une instrumentation originale pour estimer la tension des câbles est proposée. Cette instrumentation est basée sur l'utilisation d'une structure en treillis, de mécanismes compliants et de capteurs de déplacement à technologie optique pour assurer la compatibilité avec le scanner. Pour optimiser la géométrie du robot et faciliter son intégration dans l'IRM, une démarche de conception des robots à câbles instrumentés est développée. Cette démarche est basée sur une approche par intervalles. D'autres contributions relatives à la caractérisation de l'espace de travail des robots à câbles instrumentés, à l'étalonnage des capteurs de tension et au développement d'une stratégie de commande adaptée au dispositif sont décrites.
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Koch, Alexander. "Auswirkungen der koronaren Kollateralisierung bei Patienten mit akutem ST-Elevations-Myokardinfarkt und primärer perkutaner Koronarintervention." Doctoral thesis, Universitätsbibliothek Leipzig, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-146666.
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Ziel der Studie war es zu analysieren, welchen Einfluss eine angiographisch sichtbare Kollateralisierung vor Revaskularisation bei Patienten mit einem akuten ST-Elevations-Myokardinfarkt (STEMI) und primärer perkutaner Koronarintervention (PCI) auf verschiedene in der kardialen Magnetresonanztomographie messbare Parameter und auf die klinische Prognose hat. Es wurden 235 Patienten mit STEMI und einem Symptombeginn <12 Stunden in die Analyse eingeschlossen. Alle Patienten wiesen einen funktionell insuffizienten antegraden Fluss in der Infarktarterie auf. Die Patienten wurden in zwei Gruppen unterteilt: Gruppe A mit fehlender oder nur geringer Kollateralversorgung (n=166) und Gruppe B mit einer signifikanten Kollateralisierung (n=69). Es wurden Infarktgröße, mikrovaskuläre Obstruktion und linksventrikuläre Funktion mittels Magnetresonanztomographie im Median 3 Tage nach dem Infarktereignis bestimmt sowie die Patienten über einen Zeitraum von >2 Jahren nachbeobachtet. Das Ausmaß der frühen mikrovaskulären Obstruktion war in Gruppe B signifikant geringer (3,3% gegenüber 2,1% der linksventrikuläre Masse, p = 0,009). Die mittels maximaler Kreatinkinase-MB-Ausschüttung gemessene Infarktgröße war in Gruppe B kleiner (p=0,02). Bei 227 Patienten (97%) wurde nach im Median 2,2 Jahren eine klinische Verlaufskontrolle durchgeführt. Insgesamt starben während des Kontrollzeitraums 25 Patienten: 22 Patienten (13,8%) der Gruppe A mit fehlender oder nur schwacher Kollateralisierung und 3 Patienten (4,4%) der Gruppe B mit signifikanter Kollateralversorgung vor Behandlungsbeginn (p=0,04). In Gruppe A traten 12 (7,5%) nicht-tödliche Reinfarkte auf im Vergleich zu 2 (2,9%) in Gruppe B (p=0,18). Ein kombinierter Endpunkt aus Tod oder nicht-tödlichem Reinfarkt trat in Gruppe B signifikant seltener auf als in Gruppe A (p=0,02). Zusammenfassend lässt sich formulieren, dass gut ausgebildete Kollateralgefäße vor einer Revaskularisation mittels PCI bei Patienten mit akuten STEMI mit einer schützenden Wirkung auf die koronare Mikrozirkulation und einem besseren Langzeit-Überleben assoziiert sind.
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Settecase, Fabio. "Magnetically-assisted Remote Control Steering of Endovascular Catheters in Interventional MRI." Thesis, 2008. http://hdl.handle.net/1807/11163.
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Current applied to coils wound at the tip of an endovascular catheter can be used to remotely steer a catheter tip in a clinical magnetic resonance imaging (MRI) scanner. This study focuses on (1) derivation and experimental validation of an equation that characterizes the relationship between catheter tip deflection and a number of magnetic, mechanical, and physical factors, and (2) evaluation of resistive heating in a worst-case scenario due to application of current necessary for clinically significant deflections, and radiofrequency (RF) heating due to real-time MRI pulse sequences. The derived equation was found to accurately model the behavior of the specialized catheter tip. The equation also has implications for catheter design and device implementation, including minimization of resistive heating, which was physiologically significant (> 4°C) under certain worst-case scenario conditions. This catheter steering mechanism should improve navigational control and is a unique advantage offered by MRI-guidance of endovascular procedures.