FIGURE 12. Patient (64-y-old man) 2 wk after radiofrequency ablation of pulmonary metastasis in right lower pulmonary lobe. (A) Round area of necrosis and hematoma (arrows) was found postinterventionally on CT. PET imaging demonstrated rim-like area of increased glucose metabolism (B) that correlated with periphery of necrotic zone on PET/CT (C). This increase in tracer uptake in periphery of lesion may have been result of tissue regeneration or viable tumor. Further follow-up in this patient revealed decrease in peripheral tracer uptake over time. Thus, increased peripheral glucose metabolism was found to be result of tissue regeneration rather than residual tumor.