The application of contrast-enhanced ultrasound in evaluating gallbladder injury during the thermal ablation of liver tumors

Abstract

Objective To discuss the value of contrast-enhanced ultrasound (CEUS) in evaluating gallbladder injury during the thermal ablation of liver tumors adjacent to the gallbladder. Methods From January 2016 to March 2017, 40 patients with 42 hepatic tumors adjacent to the gallbladder who underwent ultrasonography-guided percutaneous microwave ablation or radiofrequency ablation in the Third Affiliated Hospital of Sun Yat-sen University were included in the study. Ultrasonography (US) was used to assess the change of gallbladder wall thickness before and after procedure. CEUS was used to assess the perfusion of gallbladder wall and determine the gallbladder injury immediately after ablation. Patients with bad perfusion of gallbladder wall accept combined treatment with cholecystectomy. The safety and therapeutic efficacy of the procedures were assessed in follow-up examinations. The change of gallbladder wallthickness were compared by signed ranks sum test. Results Assessed by US immediately after the ablations, gallbladder wall thickening adjacent to the ablated zone was noted in 8 of 40 patients. According the results of CEUS immediately after ablations, 38 patients was evaluated with good perfusion of gallbladder wall and 2 patients was evaluated with bad perfusion, who were treated with cholecystectomy. Perforation of the gallbladder was found in one of them. However, the necrosis of serosal tissue in gallbladder wall was confirmed by postoperative pathology. Another 4 patients with multiple gallbladder stones were also treated with cholecystectomy. Gallbladder wall thickening developed in six patients (17.6%) within 3 days after the ablation. Wall thickening showed complete disappearance on subsequent follow up US in 4 patients, and showed existence in 2 patients. However, complications related to the ablation such as acute cholecystitis and gallbladder perforation were not noted in 34 patients without cholecystectomy. There was significant difference in gallbladder wall thickness between preoperative and intraoperative assessment [5.00 mm (4.00-6.25 mm) vs 3.50 mm (3.00-5.00 mm), Z=-3.741, P<0.001], as well as between preoperative and postoperative assessment [5.0 mm (3.0-8.0 mm) vs 3.5 mm (3.0-5.0 mm), Z=-3.735, P<0.001]. The complete ablation rate was 97.6% (41/42) based on one-month follow-up CT or MR imaging. Local tumor progression was not found in these completely ablated tumors during the follow-up period. Conclusion Immediate post-procedural CEUS can be used to demonstrate the perfusion of gallbladder wall in US-guided ablation of hepatic tumors adjacent to the gallbladder, which is helpful to determine thermal injury of the gallbladder. Key words: Contrast-enhanced ultrasound; Liver neoplasms; Catheter ablation; Gallbladder