Figure 7c. Expected changes in an RF ablation zone over time. (a) Preablation contrast-enhanced CT scan obtained in a 78-year-old-woman shows a small, intraparenchymal RCC (arrow). (b) Immediate postablation CT scan demonstrates a wedge-shaped unenhanced region (arrows) that encompasses the renal tumor as well as some of the surrounding renal parenchyma. (c) On a CT scan obtained 3 years later, the ablation zone (arrow) shows only mild involution, a finding that demonstrates that a substantial (albeit nonviable) mass may persist years after RF ablation.