Quantitative Non-Contrast Perfusion Measurements Using Arterial Spin Labeled MRI: Evaluation of Therapy Response in Brain Tumors and Technical Advancements in Kidneys
Current radiological criteria, such as the Response Evaluation Criteria in Solid Tumors (RECIST) or the modified Response Assessment in Neuro-Oncology (RANO), primarily focus on measuring tumor size changes for treatment response assessment. However, these conventional techniques may not detect early therapy responses, as many cancer treatments initially manifest at a microscopic level before any significant change in size becomes evident. Quantitative imaging techniques can identify these early effects, providing a valuable window of opportunity to effectively manage cancer treatments. Notably, angiogenesis, a key biological process that promotes aberrant tumor neovascularization, is emerging as a vital perfusion imaging biomarker. Among all perfusion weighted imaging (PWI) techniques, arterial spin labeled (ASL) magnetic resonance imaging (MRI) has certain advantages. ASL MRI is a non-contrast and non-invasive imaging method that provides absolute quantitative measures of perfusion, proven to be especially valuable in brain imaging. Despite these advantages, ASL has not undergone robust and rigorous validation as a quantitative imaging method for evaluating cancer therapy response. We hypothesize that robust and highly reproducible ASL-measured perfusion serves as a quantitative imaging biomarker for early and accurate therapy response assessment. In part one of this thesis, we tested this hypothesis in patients with glioblastoma (GBM) with following studies: (1) Evaluating reproducibility of ASL-measured perfusion longitudinally in brain with 20 healthy volunteers and 23 GBM patients, (2) Improving the reproducibility of ASL and treatment evaluation in GBM patients by intensity normalization of ASL measured perfusion maps, (3) Investigating ASL as an alternative to dynamic susceptibility contrast (DSC), an established PWI method used clinically in GBM, (4) Evaluating the predictive value of ASL-measured baseline perfusion prior to chemoradiation therapy for survival stratification between different groups in GBM. In part two of this thesis, we extended the application of ASL into kidneys, aiming to establish ASL measured renal perfusion as a robust, accurate, and quantitative imaging biomarker with following sub-aims: (1) Improving the robustness of pseudo-continuous ASL for Renal Perfusion Imaging, (2) Proposing novel labeling strategies of 3D flow alternating inversion recovery for whole-kidney perfusion measurements.
Brain Neoplasms, Cerebrovascular Circulation, Kidney, Magnetic Resonance Imaging, Perfusion Imaging, Treatment Outcome
University of Texas Southwestern Medical Center
Networked Digital Library of Theses and Dissertations