European Journal of Ultrasound 13 (2001) 73 – 93 Clinical Science: Review Percutaneous ablation of liver malignancies: imaging evaluation of treatment response Dania Cioni, Riccardo Lencioni *, Carlo Bartolozzi Department of Oncology Transplants, Diision of Diagnostic and Interentional Radiology, Uniersity of Pisa, Via Roma 67, I -56125, Pisa, Italy Abstract Interventional procedures for percutaneous tumor ablation have gained an increasingly important role in the treatment of liver malignancies. After interventional therapies, diagnostic imaging has the key role to determine if the treated lesion is completely ablated or contains areas of residual viable neoplastic tissue. This is particularly important since in cases of incomplete necrosis of the lesions, treatment can be repeated, and tumor ablation can be further pursued. The evaluation of the therapeutic effect of the procedure arises different problems according to the histotype of the malignancy. In the case of hepatocellular carcinoma (HCC), detection of residual viable tumor is facilitated by the typical hypervascular pattern of this neoplasm. Contrast-enhanced US can be used to monitor tumor response, and, in cases of partial necrosis, to target the areas of residual viable tumor. With spiral CT or dynamic MR imaging, residual viable HCC is reliably depicted as it stands out in the arterial phase images against the unenhanced areas of coagulation necrosis. In the case of hypovascular metastases, a confident diagnosis of successfull ablation can be made when an area of thermal necrosis exceeding that of the original lesion is depicted. Peripheral inflammatory reaction following ablation procedures, that shows itself as an enhancing halo along the necrotic area boundary on spiral CT or dynamic MR images, should not be misinterpreted as tumor progression. © 2001 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Liver; Tumor; Treatment; Ultrasound; Contrast; MR; CT www.elsevier.com/locate/ejultrasou 1. Introduction Nonsurgical interventional therapies for percu- taneous tumor ablation have gained an increas- ingly important role in the treatment of liver malignancies (De Sanctis et al., 1998; Bartolozzi and Lencioni, 1999). They include the use of chemical or thermal methods of tissue destruction through the direct image-guided placement of needles or electrode-needles into the lesion, such as in percutaneous injection of ethanol and in radiofrequency (RF) thermal ablation (Lencioni and Bartolozzi, 1997a; Dalla Palma, 1998). * Corresponding author: Tel.: +39-050-992509; fax: +39- 050-551461. E-mail address: lencioni@do.med.unipi.it (R. Lencioni). 0929-8266/01/$ - see front matter © 2001 Elsevier Science Ireland Ltd. All rights reserved. PII: S0929-8266(01)00122-7