Fig. 3

Hepatocellular carcinoma. A 43-year-old male with cirrhosis undergoes gadolinium enhanced MRI, revealing a hepatocellular carcinoma in segment VII, typical for a hepatocellular carcinoma, which is confirmed through biopsy. a Twenty-four hours after RF ablation, the patient undergoes a standard unenhanced CT scan and a contrast-enhanced DECT. The unenhanced CT shows a central area of high attenuation (arrowhead) within the ablation zone, which has a lower visibility on the water map reconstruction. The central hyperdensity is well noticeable on the synthesised monochromatic 40-keV but less so on the 70-keV images, and it is hardly visible on the iodine images. On the 40- and 70-keV synthesised monochromatic images, the ablation zone can be depicted as a lesion with a hypervascular peripheral rim (white arrows). On the greyscale- and colour-coded iodine images, we can better appreciate the focal hypervascular thickening at the posterior border (yellow arrows) than with the synthesised monochromatic images. b Due to the suspicious nature of the focal thickening seen in a, a shorter follow-up period is adhered to and a DECT is performed 5 weeks post-RF ablation. A focal hypervascular nodule is well depicted on the 70-keV (white arrow) images, although more clearly observable on the 40-keV ones; however again it is more evident on the greyscale- and colour-coded iodine images. Biopsy of this region confirms residual HCC. c Twenty-four hours after the second ablation, the greyscale- and colour-coded iodine images show significant iodine rim uptake around the ablation zone in the arterial phase (arrows). Therefore, a focal hypervascular remnant cannot be appreciated. This rim disappears on the venous phase (not shown). MRI after 10 weeks reveals no signs of reactivation