"How we do it" - a practical approach to hepatic metastases ablation techniques.

Secondary liver malignancies are associated with significant mortality and morbidity if left untreated. Colorectal cancer is the most frequent origin of hepatic metastases. A multidisciplinary approach to the treatment of hepatic metastases includes medical, surgical, radiation and interventional oncology. The role of interventional oncology in the management of hepatic malignancies continues to evolve and applies to a large and continuous spectrum of metastatic disease, from the relatively small solitary metastasis to larger tumors and multifocal liver disease. Within the past 10 years, several publications of percutaneous image-guided ablation indicated the effectiveness and safety of this minimally invasive therapy for selected patients with limited number (arguably up to 4 metastases) of relatively small (less than 5cm) hepatic metastases. Different image-guided procedures such radiofrequency, microwave, and laser cause thermal ablation and coagulation necrosis or cell death of the target tumor. Cryoablation, causing cell death via cellular freezing, has also been used. Recently, irreversible electroporation, a nonthermal modality, has also been used for liver tumor ablation. In the following section, we review the different liver ablation techniques, as well as indications for ablation, specific patient preparations, and different "tricks of the trade" that we use to achieve safe and effective liver tumor ablation. We also discuss appropriate imaging and clinical patient follow-up and potential complications of liver tumor ablation.