The Use of Peak Height and Percentage Signal Recovery for Evaluation and Determination of Pseudoprogression in Glioblastoma Patients

One-third of all primary brain tumors are astrocytomas, the most common type of glioma. Grade 4 astrocytomas, more commonly known as glioblastomas (GBMs), represent about 50% of all gliomas (annual incidence of over 3 per 100,000) and are associated with high mortality rates and median patient survival of just 12-15 months post-diagnosis. Treatment response is assessed by measuring post-treatment tumor size on contrast-enhanced magnetic resonance images (MRI). However, radiation and chemotherapy cause inflammatory and necrotic changes which, like actual tumor progression itself, demonstrate contrast enhancement on the first post-treatment MRI scan. This enhancement eventually subsides (typically within 6 months of treatment) and is known as pseudoprogression (PsP). Currently, there is no gold standard noninvasive tool for distinguishing between pseudoprogression and progressive disease. Dynamic susceptibility-weighted contrast-enhanced perfusion MRI (DSC perfusion MRI) permits measurement of hemodynamic imaging variables. Previous literature reports attempted to use some or all of these metrics to assess their utility in distinguishing PsP from true cancer progression. These studies showed mixed results, likely due to a number of factors, including poor statistical power, poorly defined PsP, analysis of multiple cancer grades and types, and varied analysis methodologies. The investigators aim to address these issues in this study.