FIGURE 3. A 38-y-old man (patient 14, Table 1) with a recurrent left temporal astrocytoma. Coregistration of T1Gd MRI planes with the ¹⁸F-FDG PET planes and use of delayed imaging made evident that the small focus seen on MRI was tumor rather than radionecrosis, especially at 415 min. Subsequent MRI confirmed rapidly progressing disease.