Comparison of parallel and crossed placement of antennas in microwave ablation of 3-5cm hepatocellular carcinoma

PurposeTo evaluate the effects of ablation strategies on local tumor progression (LTP) after microwave ablation (MWA) of hepatocellular carcinomas (HCCs) measuring 3-5cm.Materials and methodsBetween December 2011 and May 2017, 71 HCC patients with 71 nodules treated by ultrasound(US)-guided percutaneous MWA were divided into parallel (group A) and crossed (group B) antenna placement groups. All patients underwent MWA using two antennas with four insertions. LTP and overall survival (OS) rates were compared between the two groups.ResultsThe median follow-up time was 16.8months. There was no significant difference in the complete ablation rate and treatment sessions between the two groups. LTP was diagnosed in 8 of 48 nodules (16.7%) in group A and 1 of 23 nodules (4.3%) in group B, with no significant difference between two groups (P=0.115). The 1-, 2-, and 3-year OS rates were 88.5%, 79%, and 71.8% in group A and 93.8%, 87.5%, and 87.5% in group B, respectively (P=0.236). Multivariate analysis showed that the tumor diameter (P=0.017), the distance between the antennas (P=0.032), and the total emission time (P=0.015) were associated with LTP.ConclusionsThere were trends with lower LTP and improved OS in group B, despite the lack of statistically significant differences between the two strategies at a level of P<0.05. The increase of distance between antennas and total emission time will facilitate reductions in LTP rate.