The optimal treatment for patients with colorectal cancer (CRC) metastases confined to the liver is surgical resection when adequate margins are feasible. Unfortunately, many patients with CRC liver metastases are not eligible for hepatic resection. Factors that preclude curative surgery include tumour location in close proximity to hilar structures, poor performance status, or inadequate hepatic reserve. Therefore, interest has focused on alternative treatment strategies. Direct thermal ablation treatments using laser, microwaves, or radiofrequency, are frequently used in clinical practice. Furthermore, the majority of patients who undergo resection of CRC liver metastases eventually develops recurrent disease.Radiofrequency thermal ablation (RFA) was first described in 1990 by Rossi and McGahan. RFA can be applied percutaneously as well as during open or laparoscopic surgery, and probe placement can be guided by ultrasonography (US), computed tomography (CT), or magnetic resonance imaging (MRI). Commercially available RFA probes have a diameter of 14-21G and induce frictional heat within tissue. A cytotoxic effect is observed at 41 deg C; immediate coagulation necrosis occurs at 90 deg C. The two main strategies that have been developed to increase the amount of ablated tumour tissue are saline cooled-tip needles and expandable-array systems.
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