To evaluate the safety and clinical efficacy of Emprint^TM microwave ablation system with Thermosphere^TM technology in the treatment of hepatocellular carcinoma (HCC).

Clinical data of 24 HCC patients admitted to the Third Affiliated Hospital of Sun Yat-sen University from January 2019 to May 2019 were retrospectively analyzed. Among them, 18 patients were male and 6 female, aged (52±11) years on average. The informed consents of all patients were obtained and the local ethical committee approval was received. The microwave ablation was performed with Emprint^TM microwave ablation system with an ablation power of 100 W. According to different ablation time of the first insertion, all lesions were divided into the 5-min and 10-min groups. The ablation range of first insertion was assessed by intraoperative contrast-enhanced ultrasound (CEUS). Complete ablation rate and the incidence of major complications induced by ablation were observed at postoperative 1 month. The ablation range of first insertion was compared between two groups by t test.

27 lesions from 24 patients were ablated with real-time ultrasound-guided Emprint^TM microwave ablation system, including 11 lesions in the 5-min group and 16 lesions in the 10-min group. The median ablation frequency was 2(1-7) times, and the total ablation time was 10(5-45) min. In the 5-min group, the maximal diameter of ablated lesions was (29.3±2.6) mm, significantly shorter than (33.7±6.7) mm in the 10-min group (t=-2.389, P<0.05). The transverse diameter, round index and ablation area in the 5-min group were (25.8±3.0) mm, 0.88±0.10, (2 384±406) mm2, which did not significantly differ from (27.0±6.3) mm, 0.81±0.14 and (2 939±1 091) mm² in the 10-min group (t=-0.657, 1.518, -1.857; P>0.05). Enhanced CT scan or MRI at postoperative 1 month showed that 25 lesions were completely ablated with a complete ablation rate of 100% except 2 cases who did not receive reexamination. Reexamination revealed no major complications related to ablation.

Emprint^TM microwave ablation system is a safe and effective method for HCC. 5-min ablation with a power of 100 W can obtain more regular and predictable spherical ablation range compared with 10-min ablation.