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dc.contributor.advisorCarpenter, T. Adrian
dc.contributor.advisorWillams, Guy
dc.contributor.authorEvans, Eleanor
dc.date.accessioned2015-11-18T15:58:36Z
dc.date.available2015-11-18T15:58:36Z
dc.date.issued2015-10-06
dc.identifier.otherPhD.38937
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/252640
dc.description.abstractIn translational medicine, complementary functional and morphological imaging techniques are used extensively to observe physiological processes in vivo and to assess structural changes as a result of disease progression. The combination of magnetic resonance imaging (MRI) and positron emission tomography (PET) provides excellent soft tissue contrast from MRI with exceptional sensitivity and specificity from PET. This thesis explores the use of sequentially acquired PET and MR images to improve the quantification of small animal PET data. The primary focus was to improve image-based estimates of the arterial input function (AIF), which defines the amount of PET tracer within blood plasma over time. The AIF is required to produce physiological parameters quantifying key processes such as metabolism or perfusion from dynamic PET images. The gold standard for AIF measurement, however, requires serial blood sampling over the course of a PET scan, which is invasive in rat studies but prohibitive in mice due to small total blood volumes. To address this issue, the geometric transfer matrix (GTM) and recovery coefficient (RC) techniques were applied using anatomical MR images to enable the extraction of partial volume corrected image based AIFs from mouse PET images. A non-invasive AIF extraction method was also developed for rats, beginning with the optimization of an automated voxel selection algorithm to assist in extracting MR contrast agent signal time courses from dynamic susceptibility contrast (DSC) MRI data. This procedure was then combined with dynamic contrast enhanced (DCE) MRI to track a combined injection of Gadolinium-based contrast agent and PET tracer through the rat brain. By comparison with gold standard tracer blood sample data, it was found that normalized MRI-based AIFs could be successfully converted into PET tracer AIFs in the first pass phase when fitted with gamma variate functions. Finally, a MR image segmentation method used to provide PET attenuation correction in mice was validated using the Cambridge split magnet PET/MR scanner’s transmission scanning capabilities. This work recommends that contributions from MR hardware in the PET field of view must be accounted forto gain accurate estimates of tracer uptake and standard uptake values (SUVs). This thesis concludes that small animal MR data taken in the same imaging session can provide non-invasive methods to improve PET image quantification, giving added value to combined PET/MR studies over those conducted using PET alone.en
dc.description.sponsorshipThis PhD project was supported by a Medical Research Council (MRC) studentship, with grant code SRAG/038.en
dc.language.isoenen
dc.rightsAll Rights Reserveden
dc.rights.urihttps://www.rioxx.net/licenses/all-rights-reserved/en
dc.subjectMagnetic Resonance Imagingen
dc.subjectMRIen
dc.subjectPositron Emission Tomographyen
dc.subjectPETen
dc.subjectAnimal imagingen
dc.subjectArterial Input Functionen
dc.subjectPartial Volume Correctionen
dc.subjectMedical Physicsen
dc.subjectAttenuation Correctionen
dc.subjectPerfusion Imagingen
dc.subjectCompartmental Modellingen
dc.subjectDynamic Imagingen
dc.subjectPET/MR Imagingen
dc.titleImproved quantification in small animal PET/MRen
dc.typeThesisen
dc.type.qualificationlevelDoctoral
dc.type.qualificationnameDoctor of Philosophy (PhD)
dc.publisher.institutionUniversity of Cambridgeen
dc.publisher.departmentDepartment of Clinical Neurosciencesen
dc.publisher.departmentWolfson Brain Imaging Centreen
dc.identifier.doi10.17863/CAM.13949
rioxxterms.freetoread.startdate2015-10-25


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