DSC-MRI in Measuring rCBV for Early Response to Bevacizumab in Patients With Recurrent Glioblastoma

Inclusion Criteria: * Histologically proven intracranial glioblastoma or gliosarcoma at initial surgery * Patients will be eligible if the original histology was low-grade glioma and a subsequent diagnosis of glioblastoma or gliosarcoma is made (high-grade transformation) * Karnofsky performance status \>= 70 * Women must not be pregnant or breast-feeding * Progression of disease assessed by local site using Revised Assessment in Neuro-Oncology (RANO) criteria, with plan to give whole-dose bevacizumab therapeutically, either as single therapy or in conjunction with other chemotherapeutic regimens; patients getting bevacizumab to support additional radiation therapy or immunotherapy, or primarily for reduction of edema rather than for tumor treatment, are excluded; this must be the patient?s initial recurrence * Patient must not have been treated previously with immunotherapies (vaccines, checkpoint inhibitors, T-cells) * Intratumoral hemorrhage (acute, subacute, or chronic) as seen on hemosiderin-sensitive (gradient-echo) MRI may preclude patient inclusion because of anticipated limited evaluation due to magnetic susceptibility artifact on the heavily T2-weighted DSC-MRI images; if the region of enhancing tumor not affected by blooming artifact on the hemosiderin-sensitive images does not meet the 10 x 10 x 10 mm ?measurable enhancement? threshold specified elsewhere, the patient is ineligible * Progressive enhancement (\> 25% increase in contrast enhancing volume compare…