Figure 1.

Abseent FMISO hypoxic volume in pseudoprogression prior to and following bevacizumab therapy. FMISO PET/MR imaging obtained simultaneously 7 days prior to (A) and 155 days after initiation of antiangiogenesis therapy (B) demonstrates pseudoprogression characterized by decreased volume of contrast enhancement (middle left) and nonenhancing FLAIR hyperintense mass (middle right) with associated focus of reduced diffusion (adc map, right). Unprocessed (left) and fused FMISO PET imaging (middle left, middle right, and right) demonstrates absence of FMISO accumulation above 1.2 time background. Pre-therapy FMISO PET/MR demonstrates slightly decreased focus of radiotracer uptake (upper left, arrow) relative to background which slightly increases to background uptake levels following bevacizumab therapy. FMISO HV is not observed at any time point in this patient with pseudoprogression.