Effect of heat sink on the recurrence of small malignant hepatic tumors after radiofrequency ablation.

Aims: The aim of this study was to investigate the effect of heat sink on the recurrence of hepatic malignant tumors <3 cm after percutaneous radiofrequency ablation (RFA). Subjects and Methods: This study included 564 hepatic malignant tumors <3 cm in 381 patients. Preoperative images were used to determine whether these tumors were adjacent to vessels, and the diameter of adjacent vessels was measured. RFA was performed computed tomography (CT), magnetic resonance imaging (MRI) and ultrasound (US) guidance, and postoperative imaging follow-up was then conducted. Statistical Analysis Used: SPSS software version 17.0 was used for data processing, and the χ 2 test was used for comparative analysis. Two-sided P < 0.05 indicated statistical significance. Results: A total of 33 recurrences were found: 15 in the MR group (15/468), 12 in the US group (12/53), and 6 in the CT group (6/43). Of the 101 lesions adjacent to blood vessels larger than 3 mm, 20 showed recurrence: 10 in the MR group (10/77), 7 in the US group (7/17), and 3 in the CT group (3/7). The recurrence rate of perivascular lesions was higher than that of nonperivascular lesions, and the rate in the MR group was lower those in the US and CT groups. Conclusions: The curative effect of MRI-guided RFA is better than those of US- and CT-guided ablation. The heat sink effect is an important factor affecting recurrence of hepatic malignant tumors after RFA.