A Comparison of MRI Perfusion and FDG PET/CT to Distinguish Between Radiation Injury and Tumor Progression

The MRI perfusion and PET/CT scans will be obtained within 12 weeks of each other. These scans are part of the standard of care for patients with brain tumors and uncertain tumor response or progression after treatment. Although every effort will be made to perform both MRI perfusion and PET/CT on the same day or during the same week, some patients may experience longer intervals between scans due to scheduling conflicts. The disease in question (radiation injury vs. tumor progression) may change slightly during this interval (e.g., the lesion may grow or shrink slightly), but no large changes are expected between the two scans. The patients may continue existing treatments in the interval between scans (e.g., steroids, chemotherapy), but the two scans must be performed before any change or new treatment occurs. Fusion images of MRI and PET/CT will not be reviewed by the neuroradiologist interpreting the MRI perfusion nor the nuclear medicine radiologist interpreting the PET/CT.