Diaphragmatic injury after radiofrequency ablation for the liver abutting the diaphragm in a rabbit model

Abstract

Objective To assess the pathological changes and outcome of diaphragmatic injury after radiofrequency ablation (RFA) for the liver abutting the diaphragm in order to provide a theoretical support of percutanous RFA for hepatocellular carcinoma abutting the diaphragm. Methods The animal models of diaphragmatic injury were made by open surgery RFA for the liver abutting the diaphragm in 10 New Zealand rabbits. Helical enhanced computed tomography (CT) was performed one week and 4 weeks after RFA. The 10 rabbits were killed immediately after the second enhanced CT, and all diaphragmatic lesions underwent gross and histologic examinations. Results Immediately after RFA, the diaphragmatic lesions were gray with an outer pale rim, and no diaphragmatic perforation occurred. The boundaries between lesions and normal area were clear. The area of diaphragmatic lesions was (0.89±0.19) cm2. No major complications, such as diaphragmatic perforation, pleural effusion and ascites, were detected on the postablation CT scan (one week or 4 weeks after the procedure). At gross inspection 4 weeks after RFA, the diaphragmatic lesions became scar-like tissue with hypertrophy of margin. Adhesion formed between the diaphragmatic lesions and the surface of hepatic RFA lesions. The area of scar was (0.73±0.17) cm2. No diaphragmatic perforation was found. On microscopic examination 4 weeks after RFA, the muscle in diaphragmatic lesions disappeared and became fibrous. Diminution, disorder and degeneration of the muscle were found in the outer rim of diaphragmatic lesions, which were replaced by fiber and lymphocyte. Conclusion It is possible to cause full-thickness diaphragmatic injury when adjacent liver is treated with RFA, but it can be repaired by scarring and there is no diaphragmatic perforation. Key words: Radiofrequency ablation; Liver; Diaphragmatic injury; Pathology