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Dissertations / Theses on the topic 'Magnetic resonance imaging and spectroscopy'

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Published: 4 June 2021

Last updated: 17 February 2022

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1

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

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2

Lei, Hao. "Magnetic resonance perfusion imaging and double quantum coherence transfer magnetic resonance spectroscopy." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0021/NQ45007.pdf.

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3

Cao, Peng, and 曹鹏. "Advanced magnetic resonance spectroscopy techniques and applications." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/202256.

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Magnetic resonance (MR) is a well-known non-invasive technique that provides spectra (by MR spectroscopy, MRS) and images (by magnetic resonance imaging, MRI) of the examined tissue with detailed metabolic, structural, and functional information. This doctoral work is focused on advanced methodologies and applications of MRS for probing cellular and molecular changes in vivo. A single-voxel diffusion-weighted (DW) MRS method was first developed for monitoring the size changes of intramyocellular lipid droplets in vivo. This DWMRS technique was then utilized for exploring the vascular origins of the functional blood-oxygen-level-dependent (BOLD) signal. Magnetic resonance spectroscopic imaging (MRSI) enables simultaneous MRS acquisition in multiple voxels. However, MRSI is conventionally time-consuming. Therefore, a compressed sensing (CS) method was proposed in this thesis to accelerate the acquisition speed of the in vivo MRSI. It holds the potential for promoting the realization of multiple-voxel DW-MRS experiments, though the latter is still constrained by hardware in the present. The single-voxel DW-MRS method for probing lipid diffusion was first developed and evaluated in oil and muscle phantoms. The experimental sequence was demonstrated to be sensitive to diffusion restriction and free of significant artifacts. Experiments were then performed in rat hindlimb muscles in vivo. The restricted lipid diffusion behavior was characterized by apparent diffusion coefficient (ADC) changes and utilized for quantifying the sizes of intramyocellular lipid (IMCL) droplets in normal, fasting, diabetic and obese rats. The sizes of IMCL droplets reflect their vital roles in muscle energy metabolism. The IMCL droplet size estimated by ADC here was closely correlated with that measured by transmission electron microscopy. IMCL ADC was sensitive to metabolic alterations, decreasing in the fasting and diabetic groups while increasing in the obese group. These results clearly demonstrate DW MRS as a new means to examine the dynamics of IMCL metabolism in vivo. The DW-MRS technique was then utilized to characterize water ADC during neuronal activation to explore the vascular origins of the BOLD signal in rat brains. MRS experiments with acoustic stimulation were performed with a dynamic point-resolved spectroscopy (PRESS) acquisition on conditions with or without the diffusion gradient for blood suppression in the same voxel and same experimental session, which enabled the simultaneous T2/T2*/diffusion measurements. The T2*% changes with and without diffusion gradient showed no significant difference, while the spin echo (SE)-BOLD% (T2%) change significantly decreased after applying the diffusion gradient, suggesting an intravascular component in the SE-BOLD signal. This intravascular component was not venous blood, as the T2* of this component was comparable with the T2* of the brain tissue. These results provide new insights into the vascular origins of BOLD signals. A CS approach was developed to accelerate in vivo magnetic resonance spectroscopic imaging (MRSI) which enables multi-voxel MRS measurements. The CS undersampling was performed by acquiring a pseudo-random and density-varying subset of phase encodings. The proposed CS approach preserved the spectral and spatial resolution, while substantially reduced the number of phase encodings with accelerations up to seven fold for phantom and up to six fold for in vivo rat brains.
published_or_final_version
Electrical and Electronic Engineering
Doctoral
Doctor of Philosophy

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4

Talagala, Sardha Lalith. "Aspects of NMR imaging and in vivo spectroscopy." Thesis, University of British Columbia, 1986. http://hdl.handle.net/2429/27550.

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The work described in this thesis deals mainly with aspects related to two- and three-dimensional NMR imaging. A detailed discussion on frequency-selective excitation using amplitude modulated rf pulses in relation to slice selection in NMR imaging has been presented. This includes the analysis and implementation of the method as well as illustrative experimental results. Several radiofrequency probe designs suitable for high field NMR imaging have been experimentally evaluated and their modification and construction are also described. The comparative results obtained indicate the merits and demerits of different designs and provide necessary guidelines for selecting the most suitable design depending on the application. Practical aspects of two- and three-dimensional imaging have been discussed and NMR images of several intact systems have been presented. Experimental methods which enable slice selection in the presence of chemically shifted species and two-dimensional chemical shift resolved imaging have "been described and illustrated using phantoms. The use of three-dimensional chemical shift resolved imaging as a potential method to map the pH and temperature distribution within an object has also been demonstrated. A preliminary investigation of the application of ³¹P NMR spectroscopy to study the biochemical transformations of the rat kidney during periods of ischemia and reperfusion has been presented.
Science, Faculty of
Chemistry, Department of
Graduate

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5

Saunders, Dawn Elizabeth. "Magnetic resonance imaging and spectroscopy in acute stroke." Thesis, King's College London (University of London), 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338664.

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6

Duce, Suzanne Louise. "Nuclear magnetic resonance imaging and spectroscopy of food." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240194.

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7

Champion, de Crespigny Alexander James Stephen. "Spatial localisation in nuclear magnetic resonance imaging and spectroscopy." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386006.

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8

Friesen, Lanette. "Magnetic resonance imaging and spectroscopy in the female pelvis." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0007/NQ41610.pdf.

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9

Domingo, Zayne. "Ischaemia following subarachnoid haemorrhage : magnetic resonance spectroscopy and imaging." Thesis, University of Oxford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360214.

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10

Popa, Emil Horia. "Algorithms for handling arbitrary lineshape distortions in Magnetic Resonance Spectroscopy and Spectroscopic Imaging." Phd thesis, Université Claude Bernard - Lyon I, 2010. http://tel.archives-ouvertes.fr/tel-00716176.

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Magnetic Resonance Spectroscopy (MRS) and Spectroscopic Imaging (MRSI) play an emerging role in clinical assessment, providing in vivo estimation of disease markers while being non-invasive and applicable to a large range of tissues. However, static magnetic field inhomogeneity, as well as eddy currents in the acquisition hardware, cause important distortions in the lineshape of acquired NMR spectra, possibly inducing significant bias in the estimation of metabolite concentrations. In the post-acquisition stage, this is classically handled through the use of pre-processing methods to correct the dataset lineshape, or through the introduction of more complex analytical model functions. This thesis concentrates on handling arbitrary lineshape distortions in the case of quantitation methods that use a metabolite basis-set as prior knowledge. Current approaches are assessed, and a novel approach is proposed, based on adapting the basis-set lineshape to the measured signal.Assuming a common lineshape to all spectral components, a new method is derived and implemented, featuring time domain local regression (LOWESS) filtering. Validation is performed on synthetic signals as well as on in vitro phantom data. Finally, a completely new approach to MRS quantitation is proposed, centred on the use of the compact spectral support of the estimated common lineshape. The new metabolite estimators are tested alone, as well as coupled with the more common residual-sum-of-squares MLE estimator, significantly reducing quantitation bias for high signal-to-noise ratio data.

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11

Kok, Trina. "Magnetic resonance spectroscopic imaging with 2D spectroscopy for the detection of brain metabolites." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78450.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.
Cataloged from PDF version of thesis. Page 94 blank.
Includes bibliographical references (p. 87-93).
While magnetic resonance imaging (MRI) derives its signal from protons in water, additional biochemical compounds are detectable in vivo within the proton spectrum. The detection and mapping of these much weaker signals is known as magnetic resonance spectroscopy or spectroscopic imaging. Among the complicating factors for this modality applied to human clinical imaging are limited chemical-shift dispersion and J-coupling, which cause spectral overlap and complicated spectral shapes that limit detection and separation of brain metabolites using MR spectroscopic imaging (MRSI). Existing techniques for improved detection include so-called 2D spectroscopy, where additional encoding steps aid in the separation of compounds with overlapping chemical shift. This is achieved by collecting spectral data over a range of timing parameters and introducing an additional frequency axis. While these techniques have been shown to improve signal separation, they carry a penalty in scan time that is often prohibitive when combined with MRSI. Beyond scan time constraints, the lipid signal contamination from the subcutaneous tissue in the head pose problems in MRSI. Due to the large voxel size typical in MRSI experiments, ringing artifacts from lipid signals become more prominent and contaminate spectra in brain tissue. This is despite the spatial separation of subcutaneous and brain tissue. This thesis first explores the combination of a 2D MRS method, _Constant Time Point REsolved SpectroScopy (CT-PRESS) with fast spiral encoding in order to achieve feasible scan times for human in-vivo scanning. Human trials were done on a 3.OT scanner and with a 32-channel receive coil array. A lipid contamination minimization algorithm was incorporated for the reduction of lipid artifacts in brain metabolite spectra. This method was applied to the detection of cortical metabolites in the brain and results showed that peaks of metabolites, glutamate, glutamine and N-acetyl-aspartate were recovered after successful lipid suppression. The second task of this thesis was to investigate under-sampling in the indirect time dimension of CT-PRESS and its associated reconstruction with Multi-Task Bayesian Compressed Sensing, which incorporated fully-sampled simulated spectral data as prior information for regularization. It was observed that MT Bayesian CS gave good reconstructions despite simulated incomplete prior knowledge of spectral parameters.
by Trina Kok.
Ph.D.

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12

Cassidy, Paul Joseph. "Radio-frequency coil design for magnetic resonance imaging and spectroscopy." Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249272.

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13

Strick, Debra Sharon. "Catheter-based magnetic resonance microcoils for microscale imaging and spectroscopy." Diss., Restricted to subscribing institutions, 2009. http://proquest.umi.com/pqdweb?did=1875373821&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.

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14

Chiu, Pui-wai, and 趙沛慧. "¹H and ³¹P brain magnetic resonance spectroscopy in aging." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B47170505.

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Magnetic Resonance Spectroscopy (MRS) was used to study the relationship between brain regional concentrations of metabolites and normal aging in Chinese. Our goal in this study is to create a database of normal aging and hence enhance further understanding on the degenerative process leading to dementia and related neurodegenerative diseases. Thirty cognitively normal healthy volunteers of age 22-82 years were recruited and the bias on gender effect in data sampling was minimized by recruiting 15 females and 15 males. In the first part of the study, 1H MRS was obtained using single-voxel-spectroscopy (SVS). Offline software java-based version of Magnetic Resonance User Interface (jMRUI) was employed for data analysis. Cerebrospinal fluid was normalized using software voxel based morphormetry (VBM). Brain morphometry data was also analyzed. Brain metabolites choline (Cho), creatine (Cr) and N-acetyl aspartate (NAA) were quantified using internal water as reference. It was found that brain metabolite concentrations of Cr, Cho and NAA increase significantly with age. Gender effect on metabolite concentrations were also discovered, being higher in the female group. For brain morphometry, white matter and grey matter volumes and fractions all reveal a siginificant negative correlation with age, whereas CSF volume and fraction show a significant positive correlation with age. Gender effect was found on grey matter, white matter and intracranial volume, being higher in the male group. In the second part of the study, 31P SVS MRS was performed on the same population of volunteers. jMRUI was also employed for data analysis. Metabolic ratios were obtained. Similar to the 1H MRS study, apart from creating a database in studying normal aging, an additional aim of this 31P MRS study is to correlate with 1H MRS and assist in interpreting the corresponding metabolic activity. Brain metabolite concentrations were found to increase significantly with age. The increase of PCr (phosphocreatine)/Ptot (total phosphorus content) in posterior cingulate suggests lower metabolic activity throughout the course of aging. The strong evidence of PDE (phosphodiester) increase with age in left hippocampus proposes the fact that phospholipid membrane breakdown will be enhanced by aging. In conclusion, MRS can act as a non-invasive tool to study aging at molecular level. Metabolite levels are significant means to investigate the metabolic change in the human brain during the process of aging as the variations in metabolite levels are believed to be footprints of biochemical changes.
published_or_final_version
Diagnostic Radiology
Master
Master of Philosophy

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15

Parikh, Jehill. "Measurement of brain temperature using magnetic resonance spectroscopic imaging." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/8082.

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The study of brain temperature is important for a number of clinical conditions such as stroke, traumatic brain injury, schizophrenia and birth asphyxia (for neonates). A direct method to estimate brain temperature non-invasively will allow assessment of brain thermoregulation and its variation in clinical conditions. Magnetic resonance imaging is a powerful technique widely used for diagnosis of a range of neurological conditions. All magnetic resonance procedures involve manipulation of the hydrogen nuclei in the water molecules of the human body. The resonance frequency of the water molecules is temperature dependent, thus MR thermometry is a powerful tool for non-invasive temperature measurement. Using internal reference MR spectroscopic imaging (MRSI), absolute brain temperature maps can be estimated. However a number of temperature independent factors influence MRSI data acquisition, thus a thorough validation is necessary and is the focus of this PhD study. In this PhD study using phantom (test object) studies it was shown that optimization of the MRSI pulse sequence is necessary to reduce systematic error in temperature maps and extensive in-vitro validation of MRSI temperature mapping was performed. A custom made temperature-controlled phantom was designed for this purpose and is presented in this thesis. MRSI data acquired from healthy (young and elderly) volunteers was employed to assess regional brain temperature variations and repeatability. Finally, the feasibility of employing fast echo planar spectroscopic imaging for volumetric MRSI temperature mapping will be presented in this thesis.

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16

Lee, Martin A. "Imaging pathology in multiple sclerosis." Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312191.

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17

Chen, Hua Hsuan. "The application of MRI and MRS in psychiatry and performance evaluation of magnetic field homogeneity in MRI : a dissertation /." San Antonio : UTHSC, 2006. http://proquest.umi.com/pqdweb?did=1155567931&sid=1&Fmt=2&clientId=70986&RQT=309&VName=PQD.

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18

Bao, Sumi. "Clinically relevant magnetic resonance imaging and spectroscopic imaging development." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/9133.

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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1999.
Includes bibliographical references (p. 129-137).
As one result of this thesis, a single slab 3D fast spin echo imaging (3DFSE) method has been implemented and optimized. This involved sequence design and implementation, SAR considerations, parameter adjustments and clinical testing. The method can deliver 3D Tl or T2 weighted brain image with isotropic Imm3 voxel resolution in approximately 10 minutes. The ability to obtain high spatial resolution in reasonable time periods has wide clinical applications such as improvement of treatment planning protocols for brain tumor patients, precise radiotherapy planning, and tissue segmentation for following the progression of diseases like multiple sclerosis. The other part of this thesis is devoted to developing and implementing spectroscopic imaging methods, which include 20 chemical shift imaging(2DCSI) methods, 20 line scan spectroscopic imaging(2D LSSI) methods, spin echo planar spectroscopic imaging(SEPSI) methods and ~ingle shot line scan spin echo planar spectroscopic imaging(SSLSEPSI) method. The former two methods are applied to oil phantoms and bone marrow studies. The SEPSI method can provide simultaneous spectroscopic measurements, R2 and R2' images and field distribution images. A time domain spectral analysis method, LP-HSVD was implemented and applied to spectroscopic imaging studies. The SEPSI method was applied to get lipid characterization of bone marrow as well as to get the R2 and R2' brain images. The SSLSEPSI method can provide instant line spectroscopic imaging which might be useful to image moving objects and can provide high temporal resolution for dynamic studies. With further development, both SEPSI and SSLSEPSI methods may prove useful for trabecular bone studies as well as functional magnetic resonance imaging( tMRI) studies.
by Sumi Bao.
Ph.D.

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19

Bossart, Elizabeth L. "Magnetic resonance imaging and spectroscopy for the study of translational diffusion applications to nervous tissue /." [Florida] : State University System of Florida, 1999. http://etd.fcla.edu/etd/uf/1999/amj9926/bossart.pdf.

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Thesis (Ph. D.)--University of Florida, 1999.
Title from first page of PDF file. Document formatted into pages; contains xiv, 137 p.; also contains graphics. Vita. Includes bibliographical references (p. 129-136).

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20

Ramamurthy, Senthil. "Localized double-quantum filtered correlated spectroscopy on 3T MRI/MRS scanner." Morgantown, W. Va. : [West Virginia University Libraries], 2005. https://etd.wvu.edu/etd/controller.jsp?moduleName=documentdata&jsp%5FetdId=4012.

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Thesis (M.S.)--West Virginia University, 2005.
Title from document title page. Document formatted into pages; contains ix, 69 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 65-69).

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21

Norén, Bengt. "Non-Invasive Assessment of Liver Fibrosis with 31P-Magnetic Resonance Spectroscopy and Dynamic Contrast Enhanced Magnetic Resonance Imaging." Doctoral thesis, Linköpings universitet, Medicinsk radiologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-90154.

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The present study aims at demonstrating phosphorus metabolite concentration changes and alterations in uptake/excretion of a hepatocyte specific contrast agent in patients with diffuse - or suspected diffuse - liver disease by applying two non-invasive quantitative MR techniques and to compare the results with histo-pathological findings, with focus on liver fibrosis. In the first study phosphorus-31 MR spectroscopy using slice selection (DRESS) was implemented. Patients with histopathologically proven diffuse liver disease (n = 9) and healthy individuals (n = 12) were examined. The patients had significantly lower concentrations of phosphodiesters (PDE) and ATP compared with controls. Constructing an ‘anabolic charge’ (AC) based on absolute concentrations, [PME] / ([PME] + [PDE]), the patients had a significant larger AC than the control subjects. The MRS technique was then, in a second study, applied on two distinct groups of patients, one group with steatosis and none-to-moderate inflammation (n = 13) and one group with severe fibrosis or cirrhosis (n = 16). A control group (n = 13) was also included. Lower concentrations of PDE and a higher AC were found in the cirrhosis group compared to the control group. Also compared to the steatosis group, the cirrhosis group had lower concentrations of PDE and a higher AC. A significant correlation between fibrosis stage and PDE and fibrosis stage and AC was found. Using an AC cut-off value of 0.27 to discriminate between mild (stage 0-2) and advanced (stage 3-4) fibrosis yielded an AUROC value of 0.78, similar as for discriminating between F0-1 vs. F2-4. Dynamic contrast enhanced MRI (DCE-MRI) was performed prospectively in a third study on 38 patients referred for evaluation of elevated serum alanine aminotransferase (ALT) and/or alkaline phosphatase (ALP) levels. Data were acquired from regions of interest in the liver and spleen by using single-breath-hold symmetrically sampled two-point Dixon 3D images time-series (non-enhanced, arterial and venous portal phase; 3, 10, 20 and 30 min) following a bolus injection of Gd-EOB-DTPA (0.025 mmol/kg). A new quantification procedure for calculation of the ‘hepatocyte specific uptake rate’, KHep, was applied on a two-compartment pharmacokinetic model. Liver-to-spleen contrast ratios (LSC_N) were also calculated. AUROC values of 0.71, 0.80 and 0.78, respectively, were found for KHep, LSC_N10 and LSC_N20 with regard to severe versus mild fibrosis. Significant group differences were found for KHep (borderline), LSC_N10 and LSC_N20. In study four no significant correlation between visual assessments of bile ducts excretion of Gd-EOB-DTPA and histo-pathological grading of fibrosis or the quantified uptake of Gd-EOB-DTPA defined as KHep and LSC_N. In conclusion 31P-MRS and DCE-MRI show promising results for achieving a non-invasive approach in discriminating different levels of fibrosis from each other.

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22

Meng, Jiqun J. "Line scan proton magnetic resonance spectroscopic imaging." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/36963.

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23

Petersen, Steffen E. "Insights into cardiac remodelling by multi-modal magnetic resonance imaging and spectroscopy." Thesis, University of Oxford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419318.

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24

Hussein, Mahamoud Omar. "Magnetic resonance imaging and spectroscopy of fat emulsions in the gastrointestinal tract." Thesis, University of Nottingham, 2013. http://eprints.nottingham.ac.uk/13582/.

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The relationship between meal structure and composition can modulate gastrointestinal processing and the resulting sense of satiety. This applies also to the fat component of meals and particularly to the surface area available for digestion. The main hypothesis underpinning this thesis work was that fat emulsion droplet size has a profound effect on fat digestion and, in turn, on the gastrointestinal and satiety responses. To test this hypothesis two fat emulsion meal systems were used. They had exactly the same composition but a small (termed the Fine emulsion, with a droplet size of 400 nm) or a large (termed the Coarse emulsion, with a droplet size of 8 μm) emulsified fat droplet size. The two fat emulsion systems were manufactured and characterised using a range of bench techniques, in vitro digestion models and MRI techniques in vitro. The difference in microstructure caused different temporal creaming characteristics for the emulsions and different percentage hydrolysis profiles in a gastric digestion model in vitro. The Fine emulsion showed initial rapid hydrolysis whilst the Coarse emulsion showed an initial slow hydrolysis phase with the hydrolysis rate increasing at later stages. This indicated that there was indeed a droplet size effect on fat hydrolysis whereby the smaller droplet size with a larger surface area hydrolysed faster than a larger droplet size. The emulsions’ performance was finally tested in vivo in healthy volunteers using MRI in a series of pilot studies leading to a main physiological study. Creaming differences in the gastric lumen were addressed by redesigning the meals using a locust bean gum (LBG) thickener that made them stable throughout the gastric emptying process. A main three-way physiological and satiety study in healthy volunteers showed that a highly emulsified, intragastrically stable emulsion delayed gastric emptying, increased small bowel water content and reduced consumption of food at the end of the study day. Finally, magnetic resonance imaging, relaxometry and spectroscopy were further evaluated to assess fat emulsion parameters in vitro and in vivo in the gastric lumen. Main static magnetic field and droplet size effects on T2 relaxation times of the Fine and the Coarse emulsions were observed. There was reasonable correlation between m-DIXON and spectroscopy methods to quantify fat fraction both in vitro and in vivo. Differences in T2 relaxation times for different droplet sizes of 20% fat emulsions were detected in vitro. These changes were however difficult to separate from creaming effects in vivo with a view of drawing meaningful inferences on droplet sizes. The main conclusion from this work was that manipulating food microstructure especially intragastric stability and fat emulsion droplet size can influence human gastrointestinal physiology and satiety responses and that MRI and MRS provide unique non invasive insights into these processes. This improved knowledge could help designing foods with desired health-promoting characteristics which could help to fight the rising tide of obesity.

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25

Arvanitis, Theodoros N. "A study of respiratory motion artifacts in magnetic resonance imaging and spectroscopy." Thesis, University of Sussex, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320361.

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26

Cobbold, Jeremy Francis Lars. "Imaging techniques in chronic liver disease : applications of proton magnetic resonance spectroscopy." Thesis, Imperial College London, 2008. http://hdl.handle.net/10044/1/11263.

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27

Roberts, Timothy Paul Leslie. "Radiofrequency pulse design for use in nuclear magnetic resonance imaging and localized spectroscopy." Thesis, University of Cambridge, 1992. https://www.repository.cam.ac.uk/handle/1810/283680.

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28

Gu, Meng. "High-speed volumetric ¹H magnetic resonance spectroscopic imaging /." May be available electronically:, 2008. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.

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29

Chatnuntawech, Itthi. "Model-based reconstruction of magnetic resonance spectroscopic imaging." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/82376.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2013.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 77-80).
Magnetic resonance imaging (MRI) is a medical imaging technique that is used to obtain images of soft tissue throughout the body. Since its development in the 1970s, MRI has gained tremendous importance in clinical practice because it can produce high quality images of diagnostic value in an ever expanding range of applications from neuroimaging to body imaging to cancer. By far the dominant signal source in MRI is hydrogen nuclei in water. The presence of water at high concentration (-50M) in body tissue, combined with signal contrast modulation induced by the local environment of water molecules, accounts for the success of MRI as a medical imaging modality. As opposed to conventional MRI, which derives its signal from the water component, magnetic resonance spectroscopy (MRS) acquires the magnetic resonance signal from other chemical components, most frequently various metabolites in the brain, but also signals from tumors in breast and prostate. The spectroscopic signal arises from low concentration (-1 - 10mM) compounds, but in spite of the challenges posed by the resulting low signal-to-noise ratio (SNR), the development of MRS is motivated by the desire to directly observe signal sources other than water. The combination of MRS with spatial encoding is called magnetic resonance spectroscopic imaging (MRSI). MRSI captures not only the relative intensities of metabolite signals at each voxel, but also their spatial distributions. While MRSI has been proven to be clinically useful, it suffers from fundamental tradeoffs due to the inherently low SNR, such as long acquisition time and low spatial resolution. In this thesis, techniques that combine benefits from both model-based reconstruction methods and regularized reconstructions with prior knowledge are proposed and demonstrated for MRSI. These methods address constraints on acquisition time in MRSI by undersampling data during acquisition in combination with improved image reconstruction methods.
by Itthi Chatnuntawech.
S.M.

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30

Chen, Chen. "Quantitative magnetic resonance imaging studies of extended drug release systems." Thesis, University of Cambridge, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708155.

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31

Storrs, Judd M. "Automatic Real-time Targeting of Single-Voxel Magnetic Resonance Spectroscopy." University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1282576722.

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32

Sawbridge, Rebecca Joanne. "Developments in magnetic resonance spectroscopic imaging acquisition and analysis." Thesis, University of Birmingham, 2018. http://etheses.bham.ac.uk//id/eprint/8050/.

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Magnetic Resonance Spectroscopic Imaging (MRSI), a functional MR imaging technique, has proven via the identification of metabolite biomarkers to be useful in the diagnosis and prognosis of numerous diseases, for example brain tumours. However, a number of factors impede its routine clinical use: i) long acquisition times mean its use is limited to low resolution 2-dimensional slabs, ii) large quantity of data produced means its interpretation can be time consuming and iii) data quality can be variable and therefore interpretation can be difficult for a non-expert. Further developments in MRSI are designed to reduce the impact of these issues. The focus of this work is to address some of the above issues; developing acquisition protocols and optimising analysis methods in order to increase the clinical feasibility of MRSI. Within this study a fast-MRSI protocol has been developed for absolute metabolite quantitation and has demonstrated its feasibility for clinical use, accurately reproducing data in a shorter clinically feasible acquisition time. An experimentally derived fitting model has been developed which increases metabolite measurement accuracy. Finally, a 3D MRSI protocol has been successfully optimized allowing robust metabolite information to be mapped throughout the brain.

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33

Gagoski, Borjan Aleksandar. "Fast magnetic resonance spectroscopic imaging using RF coil arrays." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/37930.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2006.
Includes bibliographical references (p. 71-73).
Conventional Magnetic Resonance Spectroscopic Imaging (MRSI) suffers from both low signal-to-noise (SNR), as well as long acquisition times. The development of high-fidelity gradient coils has opened opportunities for fast k-space encoding schemes that are already used in structural imaging. At the same time, receive-coil arrays using 4 and 23 channels have been developed and reported to produce improved SNR over conventional quadrature detection by single coils. Fast spectroscopic imaging algorithm using spiral k-space trajectories and multiple-channel coil arrays is proposed in order to overcome the long acquisition-time limitations of conventional MRSI.
by Borjan Aleksandar Gagoski.
S.M.

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Gagoski, Borjan Aleksandar. "Magnetic resonance spectroscopic imaging using parallel transmission at 7T." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/63069.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2011.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 123-130).
Conventional magnetic resonance spectroscopic imaging (MRSI), also known as phase-encoded (PE) chemical shift imaging (CSI), suffers from both low signal-to-noise ratio (SNR) of the brain metabolites, as well as inflexible tradeoffs between acquisition time and spatial resolution. In addition, although CSI at higher main field strengths, e.g. 7 Tesla (T), offers improved SNR over clinical 1.5T or 3.OT scanners, the realization of these benefits is limited by severe inhomogeneities of the radio frequency (RF) excitation magnetic field (B,+), which is responsible for significant signal variation within the volume of interest (VOI) resulting in spatially dependent SNR losses. The work presented in this dissertation aims to provide the necessary means for using spectroscopic imaging for reliable and robust whole brain metabolite detection and quantification at high main field strengths. It addresses the challenges mentioned above by improving both the excitation and the readout components of the CSI acquisition. The long acquisition times of the PE CSI are significantly shortened (at least 20 fold) by implementing the time-efficient spiral CSI algorithm, while the B1 non-uniformities are corrected for using RF pulses designed for new RF excitation hardware at 7T, so-called parallel transmission (pTx). The B1 homogeneity of the pTx excitations improved at least by a factor of 4 (measured by the normalized spatial standard deviations) compared to conventional single channel transmit systems. The first contribution of this thesis describes the implementation of spiral CSI algorithm for online gradient waveform design and spectroscopic image reconstruction with standard clinical excitation protocols and applied in studies of Late-Onset Tay- Sachs (LOTS), adrenoleukodystrophy (ALD) and brain tumors. A major contribution of this thesis is pTx excitation design for CSI to provide spectral-spatial mitigation of the B1+ inhomogeneities at 7T. Novel pTx RF designs are proposed and demonstrated to yield excellent flip angle mitigation of the brain metabolites, and also enable improved suppression of the undesired water and lipid signals. A major obstacle to the deployment of 7T pTx applications for clinical imaging is the monitoring and management of local specific absorption rate (SAR). This thesis also proposes a pTx SAR monitoring system with real-time RF monitoring and shut-off capabilities.
by Borjan Aleksandar Gagoski.
Ph.D.

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Wild, James Michael. "Proton magnetic resonance spectroscopic imaging of the human brain." Thesis, University of Edinburgh, 1998. http://hdl.handle.net/1842/22742.

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Over the last ten years proton NMR spectroscopy has been performed on clinical MRI scanners using single voxel localisation and spectroscopic imaging sequences. In this work inner volume excitation of a transverse imaging plane within the brain has been used to obtain single slice spectroscopic images of proton metabolites. The existing image processing protocols used to construct the metabolite images were improved and optimised so as to give as accurate a picture of metabolite distribution as possible. Inaccuracy in these images can be introduced by the excitation profile of the radio frequency pulses used in inner volume excitation. A new normalisation technique is proposed which will remove these inaccuracies enabling more reliable quantification of metabolite concentrations. Of particular importance in stroke is the metabolite lactate, elevated levels of which are symptomatic with the conditions of anaerobic glycolysis that are thought to precede infarction. The signal from lactate is often obscured by lipid and macro-molecule resonances in the same frequency range. Lactate editing sequences compatible with the hardware capabilities of the scanner and spectroscopic imaging sequences were investigated for viability in-vivo. Using two different editing sequences lactate editing was performed successfully in vitro and in vivo. In-vivo results are presented from a study of 40 stroke patients and a smaller pilot study of 8 head injury patients. These patients were drawn from the Lothian Stroke Register as part of the Clinical Research Initiative (CRI) in stroke and head injury being co-ordinated at the Western General Hospital, Edinburgh. To our knowledge this is the largest proton spectroscopic study of acute stroke patients and as such should have a significant bearing in analysing the physiological implications of the disease.

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Neves, André Tiago Rebelo Marques de Albuquerqu. "Studies of tissue-engineered meniscal cartilage in vitro using magnetic resonance imaging and spectroscopy." Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.615759.

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Chang, Henry. "Magnetic Resonance Imaging and Spectroscopy in the Evaluation and Management of Acute Coronary Syndrome." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1429802520.

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Dzien, Piotr. "The development of novel tools for in vivo molecular imaging using hyperpolarised ¹³C labelled molecules and ¹³C magnetic resonance spectroscopy and spectroscopic imaging." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708714.

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Faraj, Achraf Al. "Biodistribution and biological impact of nanoparticles using multimodality imaging techniques : (Magnetic resonance imaging)." Phd thesis, Université Claude Bernard - Lyon I, 2009. http://tel.archives-ouvertes.fr/tel-00696221.

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As novel engineered nanoparticles such as single-walled carbon nanotubes (SWCNT) are extensively used in nanotechnology due to their superior properties, it becomes critical to fully understand their biodistribution and effect when accidently inhaled. There fore, development of animaging technique which allow longitudinal in vivo follow-up of SWCNT effect based on their intrinsic properties is highly desirable. Non invasive free-breathing hyperpolarized 3He lung MRI protocol was developed complementary to proton systemic MR protocol to allow monitoring SWCNT based on their intrinsic iron impurities after intrapulmonary exposition. Combined toproton lung MRI and ex vivo optical and electron microscopy at different time points, this protocol represents a powerful multimodality imaging techniques which allows a full characterization of the biodistribution and biological impacts of iron containing SWCNT. SWCNT was found to produce granulomatous and inflammatory reactions in a time and dose dependent manner with their bio persistenc eafter intrapulmonary exposition.From biological impact evaluations after intrapulmonary exposition towards biomedical applications, SWCNT hold promise for applications in nanomedicine field with their distinct architecture and their novel physicochemical properties. The biodistribution and pharmacological profile of various well-dispersed pristine and functionalized SWCNT were assessed in blood and target tissues after their intra venous administration by longitudinal in vivo susceptibility weighted MRI and their potential effect on liver metabolism by ex vivo HRMAS 1H NMR. No presence ofacute toxicological effect (variation in liver metabolism) was observed confirmed by the absence of clustering in NMR spectra using Principal Component Analysis (specific biomarkers of toxicity).

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Li, Chao. "Characterising heterogeneity of glioblastoma using multi-parametric magnetic resonance imaging." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/287475.

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A better understanding of tumour heterogeneity is central for accurate diagnosis, targeted therapy and personalised treatment of glioblastoma patients. This thesis aims to investigate whether pre-operative multi-parametric magnetic resonance imaging (MRI) can provide a useful tool for evaluating inter-tumoural and intra-tumoural heterogeneity of glioblastoma. For this purpose, we explored: 1) the utilities of habitat imaging in combining multi-parametric MRI for identifying invasive sub-regions (I & II); 2) the significance of integrating multi-parametric MRI, and extracting modality inter-dependence for patient stratification (III & IV); 3) the value of advanced physiological MRI and radiomics approach in predicting epigenetic phenotypes (V). The following observations were made: I. Using a joint histogram analysis method, habitats with different diffusivity patterns were identified. A non-enhancing sub-region with decreased isotropic diffusion and increased anisotropic diffusion was associated with progression-free survival (PFS, hazard ratio [HR] = 1.08, P < 0.001) and overall survival (OS, HR = 1.36, P < 0.001) in multivariate models. II. Using a thresholding method, two low perfusion compartments were identified, which displayed hypoxic and pro-inflammatory microenvironment. Higher lactate in the low perfusion compartment with restricted diffusion was associated with a worse survival (PFS: HR = 2.995, P = 0.047; OS: HR = 4.974, P = 0.005). III. Using an unsupervised multi-view feature selection and late integration method, two patient subgroups were identified, which demonstrated distinct OS (P = 0.007) and PFS (P < 0.001). Features selected by this approach showed significantly incremental prognostic value for 12-month OS (P = 0.049) and PFS (P = 0.022) than clinical factors. IV. Using a method of unsupervised clustering via copula transform and discrete feature extraction, three patient subgroups were identified. The subtype demonstrating high inter-dependency of diffusion and perfusion displayed higher lactate than the other two subtypes (P = 0.016 and P = 0.044, respectively). Both subtypes of low and high inter-dependency showed worse PFS compared to the intermediate subtype (P = 0.046 and P = 0.009, respectively). V. Using a radiomics approach, advanced physiological images showed better performance than structural images for predicting O6-methylguanine-DNA methyltransferase (MGMT) methylation status. For predicting 12-month PFS, the model of radiomic features and clinical factors outperformed the model of MGMT methylation and clinical factors (P = 0.010). In summary, pre-operative multi-parametric MRI shows potential for the non-invasive evaluation of glioblastoma heterogeneity, which could provide crucial information for patient care.

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Mei, Chang-Sheng. "Accelerated MR Thermometry for High Intensity Focused Ultrasound Therapy." Thesis, Boston College, 2011. http://hdl.handle.net/2345/2425.

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Thesis advisor: Michael Graf
The purpose of this dissertation was to investigate the temporal limit on the ability to measure temperature changes using magnetic resonance imaging (MRI). The limit was examined in experiments using a variety of imaging techniques for MRI-based temperature measurements. We applied these methods for monitoring temperature changes in focused ultrasound (FUS) heating experiments. FUS is an attractive alternative to surgical resection due to its noninvasive character. FUS treatments have been successfully conducted in several clinical applications. MRI and MR thermometry is a natural choice for the guidance of FUS surgeries, given its ability to visualize, monitor, and evaluate the success of treatments. MR thermometry, however, can be a very challenging application, as good resolution is often needed along spatial, temporal as well as temperature axes. These three quantities are strictly related to each other, and normally it is theoretically impossible to simultaneously achieve high resolutions for all axes. In this dissertation, techniques were developed to achieve this at cost of some reduction in spatial coverage. Given that the heated foci produced during thermal therapies are typically much smaller than the anatomy being imaged, much of the imaged field-of-view is not actually being heated and may not require temperature monitoring. By sacrificing some of the in-plane spatial coverage outside the region-of-interest (ROI), significant gains can be obtained in terms of temporal resolution. In the extreme, an ROI can be chosen to be a narrow pencil-like column, and a sampling time for temperature imaging is possible with a temporal resolution of a few milliseconds. MRI-based thermal imaging, which maps temperature-induced changes in the proton resonance frequency, was implemented in two projects. In the first project, three previously described, fast MR imaging techniques were combined in a hybrid method to significantly speed up acquisition compared to the conventional thermometry. Acceleration factors up to 24-fold were obtained, and a temporal resolution as high as 320 milliseconds was achieved. The method was tested in a gel phantom and in bovine muscle samples in FUS heating experiments. The robustness of the hybrid method with respect to the cancellation of the fat signal, which causes temperature errors, and the incorporation of the method into an ultrafast, three dimensional sequence were also investigated. In the second project, a novel MR spectroscopic sequence was investigated for ultrafast one-dimension thermometry. Temperature monitoring was examined during FUS sonications in a gel phantom, SNR performance was evaluated in vivo in a rabbit brain, and feasibility was tested in a human heart. It was shown capable in a FUS heating experiment in a gel phantom of increasing temporal resolution to as high as 53 milliseconds in a three Tesla MRI. The temporal resolution achieved is an order of magnitude faster than any other rapid MR thermometry sequences reported. With this one-dimensional approach, a short sampling time as low as 3.6 milliseconds was theoretically achievable. However, given the SNR that could be achieved and the limited heating induced by FUS in the gel phantom in a few milliseconds, any temperature changes in such a short period were obscured by noise. We have analyzed the conditions whereby a temporal resolution of a few-milliseconds could be obtained
Thesis (PhD) — Boston College, 2011
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Physics

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Totenhagen, John. "Magnetic Resonance Imaging and Spectroscopy of a Mouse Model of Niemann Pick Type C1 Disease." Diss., The University of Arizona, 2012. http://hdl.handle.net/10150/217112.

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Niemann Pick Type C (NPC) disease is a rare genetic disease which is most often diagnosed in children, causes tragic irreversible neurologic deterioration, and is universally fatal. Many therapies and treatments are in development and would benefit from improved methods of assessing disease progression and treatment response. A large amount of NPC research is carried out in animal models such as the Npc1^(-/-) mouse model of the most common type of NPC disease, NPC1. This dissertation investigates three methods of noninvasive assessments of disease state in the Npc1^(-/-) mouse model with the use of magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS).MRI and MRS provide safe and widely available methods of measuring and visualizing internal tissue characteristics, suitable for longitudinal studies of disease progression and response to therapy. In this work, disease-associated dysmyelination of white matter tracts in the brain of Npc1^(-/-) mice was quantitatively measured at multiple time points with MRI methods of diffusion tensor imaging (DTI) and T2-mapping. These quantitative in vivo measures of disease status show promise as biomarkers for use in future studies of disease progression and treatment response in NPC disease models. High resolution MRI data was also collected and analyzed at multiple time points to quantify differences in both global and regional brain volumes in the Npc1^(-/-) mice as brain atrophy develops with disease progression. MRS was utilized to quantitatively examine changes in brain metabolite levels previously reported in clinical NPC disease studies. The results of the MRI and MRS studies in the Npc1^(-/-) mouse model demonstrate the ability to quantify changes in the brain due to neurodegeneration at multiple time points along the progression of neurological Npc1^(-/-) disease. MRI methods of quantifying white matter pathology with currently available DTI and T2-mapping techniques appear to be promising in vivo biomarkers of disease in the brain for future studies, while quantification of volumetric changes due to brain atrophy currently shows changes only at later disease stages. In vivo MRS with currently available methodology provides insight into the neurodegenerative disease pathology in the Npc1^(-/-) mouse but appears to lack sensitivity as a biomarker.

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Murphy, Anna. "An investigation into the partial agonism of aripiprazole using functional magnetic resonance imaging and spectroscopy." Thesis, University of Manchester, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.525172.

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Lenoir, Marc. "Structure determination of contrast agents for angiogenesis imaging by high resolution nuclear magnetic resonance spectroscopy." Thesis, University of Edinburgh, 2006. http://hdl.handle.net/1842/12405.

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Structure of bicyclic pseudo octapeptides containing a sequence arginine-glycine-aspartic acid (RGD peptides) was investigated by high-resolution NMR spectroscopy. The compounds, synthesized by General Electric Healthcare, are used as contract agents in imaging of cancer. Structures were generated using different protocols in vacuum or explicit solvent. The best results were obtained through the analysis of a series of NOESY spectra acquired using varying mixing times. Full relaxation matrix analysis in explicit solvent was performed on these data yielding a consistent set of structure. The polyethylene glycol moiety and the metal binding site did not show any signs of tertiary structure. The distance restraints for structure calculations were supplemented by dihedral restraints provided by the analysis of vicinal coupling constants. Towards this end, an extensive set of coupling constants related to dihedral angles of amino acids was obtained. Various experiments, including HMBC, HSQC and HETLOC, were evaluated yielding a basic set of experiments suitable for the measurement of coupling constants of peptides with natural abundance of isotopes. The structures of the studied peptides were found to be similar and to adopting a reverse γ-turn centered on the aspartic acid of the RGD motif. Despite the bicycling nature of these peptides the compounds showed signs of flexibility, which was more pronounced in H2O. Side chains of the compounds are flexible as implied from the analysis of the distributions of cl angles. Structures were determined in two solvents, H2O and DMSO. It was found that the water based structures are more extended, while the DMSO based structure are more compact. DMSO structure of one peptide was compared with a published NMR structure of a similar peptide and a good agreement was found for the common RGD loop. The water based structures are similar to a published X-ray structure of a RGD peptide in complex with αvβ3.

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Janse, van Rensburg Leon. "The application of magnetic resonance and computed tomography imaging in the diagnosis and management of maxillofacial tumours." Thesis, University of Western Cape, 2004. http://etd.uwc.ac.za/index.php?module=etd&amp.

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The Application of Magnetic Resonance (MRI) and Computed Tomography Imaging (CT) in the Diagnosis and Management of Maxillofacial Tumours. For decades maxillofacial surgeons over the world have been frustrated by the high and often fatal recurrence of certain advanced jaw tumours. This study conclusively proves that Computed Tomography and especially Magnetic Resonance Imaging significantly decreases recurrence of Odontogenic Keratocyst and Ameloblastoma and allows surgical planning to avoid these recurrences.

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46

Røe, Kathrine. "In vivo Magnetic Resonance Spectroscopy and Diffusion Weighted Magnetic Resonance Imaging for Non-Invasive Monitoring of Treatment Response of Subcutaneous HT29 Xenografts in Mice." Thesis, Norwegian University of Science and Technology, Department of Electronics and Telecommunications, 2006. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-9441.

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This work investigates whether in vivo magnetic resonance spectroscopy (MRS) and diffusion-weighted magnetic resonance imaging (DW-MRI) can be used for non-invasive monitoring of treatment response in an experimental tumor model. Twenty-nine nude mice with colorectal adenocarcinoma HT29 xenografts on each flank were included into 2 separate experiments. In the first experiment control tumors were compared to tumors irradiated with 15 Gy at Day 2. MR baseline values were established at Day 1 followed by 4 post-treatment MR examinations. Mice were sacrificed for histological response evaluation and high-resolution ex vivo magic angle spinning (HR-MAS) MRS of tumor tissue samples for correlation with in vivo MR data. The second experiment included 3 groups recieving combined chemoradiation therapy; Control group, Capecitabine (359 mg/kg daily Day 1 - Day 5) group and Capecitabine (359 mg/kg daily Day 1 - Day 5) + Oxaliplatin (10 mg/kg at Day 2) group. All left-sided tumors were irradiated with 15 Gy at Day 2. Three repeated MR examinations were compared to the MR baseline values established at Day 1. After MR examinations the mice were sacrificed for histological response evaluation. The choice of chemoterapy was based on a clinical patient study currently running at Rikshospitalet-Radiumhospitalet HF, the LARC-RRP (Locally Advanced Rectal Cancer - Radiation Response Prediction) study. In Experiment 1, localized 1H MR spectra were acquired at short (35 ms) and long (144 ms) echo times (TEs) using a single-voxel technique. The metabolite choline is related to tumor growth. The choline peak area relative to the unsuppressed 35 ms TE water area in the same voxel, i.e. the normalized choline ratio, was assessed in all MRS examinations. For both TEs, the choline ratio increased after irradiation, followed by a decrease and a renewed increase 12 days after irradiation. In Experiment 1, statistically significant differences at the 0.1 level were observed between the choline ratios at Day 5 and Day 12 (p = 0.068) for short TE and between the ratios at Day 3 and Day 8 (p = 0.05) for long TE. The change in choline ratio was in accordance with the tumor necrotic fraction (NF) found in histological analyses. Principal component analysis (PCA) revealed a correlation between the score values of ex vivo HR-MAS MR spectra and necrosis. This suggests a correlation between ex vivo and in vivo MRS. In both experiments, the diffusion in the HT29 xenografts varied during treatment. There was a correlation between the amount of necrosis in tumor and the calculated apparent diffusion coefficient (ADC) obtained from DW-MRI examinations. In Experiment 1, statistically significant differences at the 0.1 level were observed between the ADCs at Day 3 and Day 5 (p = 0.05), between Day 5 and Day 12 (p = 0.068), and between Day 8 and Day 12 (p = 0.068). The HT29 xenografts responded to treatment with an initial increase of necrosis due to the short-term effect of treatment, stimulating development of fibrosis. In accordance to the change in choline and ADC, the level of necrosis increased 8 - 12 days after start of treatment, which might correspond to the long-term effect of treatment. The findings in this work shows that in vivo MRS and DW-MRI can be used for non-invasive monitoring of treatment response in an experimental tumor model. This suggests that in vivo MRS and DW-MRI could yield important information about a tumors response to therapy.

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Lee, Shen-Han. "¹H magnetic resonance spectroscopic imaging of tumour extracellular pH : the role of carbonic anhydrase IX." Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.607910.

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Schroeder, Marie Allen. "Development of novel hyperpolarized magnetic resonance techniques for metabolic imaging of the heart." Thesis, University of Oxford, 2009. http://ora.ox.ac.uk/objects/uuid:9c5b6638-c71e-4eec-835b-e2cea3b9106e.

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The advent of hyperpolarized magnetic resonance (MR) has provided new potential for real-time visualization of in vivo metabolic processes. The aim of the work in this thesis was to use hyperpolarized substrates to study rapid metabolic processes occurring in the healthy and diseased rat heart. Initial work, described in Chapter 2, optimized the hyperpolarization process to reproducibly generate tracers. Chapter 3 describes use of hyperpolarized 1-13C-pyruvate to investigate in vivo flux through the regulatory enzyme pyruvate dehydrogenase (PDH). Cardiac PDH activity was altered in several physiological and pathological states, namely fasting, type 1 diabetes, and high-fat feeding, and in vivo flux through PDH was measured using hyperpolarized MR. These measurements correlated with measurements of in vitro PDH activity obtained using a validated biochemical assay. The work in Chapter 4 investigated the physiological interaction between hyperpolarized tracer and cardiac tissue. The effect of hyperpolarized 1-13C-pyruvate concentration on its in vivo metabolism was analyzed using modified Michaelis-Menten kinetics. It was found that hyperpolarized MR could non-invasively follow mechanisms of metabolic regulation, in addition to reporting enzyme activity. In Chapter 5, hyperpolarized MR was incorporated into the isolated perfused rat heart. 1-13C-pyruvate in normal and ischaemic hearts revealed significant differences in lactate metabolism, and provided the foundation for a novel intracellular pH probe. Infusion of 2-13C-pyruvate in the isolated rat heart enabled the first real-time visualization of Krebs cycle intermediates. In summary, the work in this thesis has highlighted the potential of hyperpolarized MR to reveal novel information on heart disease.

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Dyke, Stephanie Odette Mary. "Investigating tumour response to the anti-vascular drug combretastatin A₄ using magnetic resonance imaging and spectroscopy." Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.598715.

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Anti-vascular cancer therapy is based on experimental evidence that the growth of solid tumours relies on the development and continual expansion of a host-derived vascular network to feed the proliferating mass of cancer cells. Combretastatin A4 (CA4) has emerged as a promising anti-vascular drug as it specifically damages tumour vasculature, leading to extensive secondary cancer cell death, without significantly impairing healthy tissue perfusion. The aim of this research was to further our understanding of CA4’s mode of action, and in particular address the hypothesis that CA4 is active upon proliferating (angiogenic) but not quiescent blood vessels in vivo. Two experimental approaches using human tumour models xenografted in mice were adopted for this purpose. In the first, tumour vascular proliferation was limited within a CA4-senstivie tumour model using the anti-angiogenic drug, vascular endothelial growth factor (VEGF) receptor tyrosine-kinase inhibitor\SU. This was shown to significantly reduce the tumour’s vascular response to CA4 treatment as assessed by magnetic resonance imaging and spectroscopy. Secondly, a relatively CA4-resistant tumour model was genetically modified to overexpress VEGF, a major mediator of the angiogenic process. The vasculature of these tumours was shown to be sensitised to the vascular-damaging effects of CA4. The results of this research suggest that CA4 specifically targets angiogenic tumour vessels in vivo. This work provides a biological explanation for the drug’s specificity for tumour versus healthy vessels, and more specifically, can explain the wide variation in tumour response to this anti-vascular drug.

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Obi, Aghogho A. "A novel radio frequency coil design for breast cancer screening in a magnetic resonance imaging system." Worcester, Mass. : Worcester Polytechnic Institute, 2003. http://www.wpi.edu/Pubs/ETD/Available/etd-0114104-103813/.

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