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Figure 9c.   CT evaluation of microwave ablation performed in a 68-year-old man with hepatocellular carcinoma who had previously been treated with arterial chemoembolization with iodized oil. (a) Enhanced CT scan obtained before embolization shows a hypervascular tumor nodule (arrowheads). (b) Unenhanced CT scan obtained 7 days after embolization shows incomplete accumulation of iodized oil in the tumor (arrow). (c) Sonogram obtained before microwave ablation (left) shows a 35-mm hypoechoic nodule in the anterior segment of the right hepatic lobe (arrows). Sonogram obtained immediately after treatment (two emissions) (right) shows a markedly echogenic region of coagulation (arrow) that has replaced the tumor. (d) Enhanced CT scan obtained 4 days after microwave ablation shows ablated tissue as unenhanced areas within and around the tumor (arrows). (e) Dynamic CT scan obtained 9 months after treatment shows that the lesion (arrow) has decreased in size, without evidence of new tumor growth.