Assessment of therapeutic effect of liver tumor ablation procedures

Interventional procedures for percutaneous tumor ablation have gained an in creasingly important role in the treatment of liver malignancies. After int erventional therapies, diagnostic imaging has the key role in determining i f the treated lesion is completely ablated or contains areas of residual vi able neoplastic tissue. This is particularly important since in case of inc omplete necrosis of the lesion, treatment can be repeated, and tumor ablati on can be further pursued. The evaluation of the therapeutic effect of the procedure leads to different problems according to the histotype of the mal ignancy. In the case of hepatocellular carcinoma, detection of residual via ble tumor is facilitated by the typical hypervascular pattern of this neopl asm. Contrast-enhanced color Doppler ultrasonography can be used to monitor tumor response, and, in case of partial necrosis, to target the areas of r esidual viable tumor. With spiral computed tomography or dynamic magnetic r esonance imaging, residual viable hepatocellular carcinoma tissue is reliab ly depicted as it stands out in the arterial phase images against the unenh anced areas of coagulation necrosis. In the case of hypovascular metastases , a confident diagnosis of successful ablation can be made when an area of thermal necrosis exceeding that of the original lesion is depicted. Periphe ral inflammatory reaction following ablation procedures should not be misin terpreted as tumor progression.