FIGURE 4. A 59-y-old woman (patient 6, Table 1) with a progressive memory disorder and seizures whose multiple MRI scans demonstrated an extensive intraaxial infiltrating mass predominantly in the right temporal lobe but also involving the splenium of the corpus callosum and contralateral temporal lobe. The initial clinical and radiographic diagnosis was low-grade glioma. She declined treatment. Gadolinium contrast enhancement appeared on T1-weighted MR images 2 y after presentation, at which time she underwent ¹⁸F-FDG PET. Autopsy 19 mo after PET showed a mixed glioma, WHO grade III. ¹⁸F-FDG uptake was decidedly more prominent at the later times, 82 and 315 min, than at 45 min.