Laparoscopic radiofrequency of hepatocellular carcinoma. Preliminary results

GASTROENTEROLOGY Vol. US, No.4

A912 AASLD ABSTRACTS

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OBSERVATION OF LIVER TISSUE DAMAGE AFTER RADIOFREQUENCY ABLATION BY ELECTRON MICROSCOPE.

COMPARISON BETWEEN RADIOFREQUENCY ABLATION AND PERCUTANEOUS MICROWAVE COAGULATION THERAPY FOR HEPATOCELLULAR CARCINOMA. Harukazu Kouyama, Teruaki Kawanisi, Kenichirou Gotou, Hirosi Kanagawa, Satoaki Mirna, Inazumi Park Hosp, Sapporo, Japan.

Ryoko Kuromatsu, Masatoshi Tanaka, Yoshihiro Shimauchi, Riko Ogata, Satoshi llano, Yukio Tateishi, Koji Okuda, Syuichi Fukuda, Michio Sata, Kurume Univ Sch of Medicine, Kurume, Japan. Background/Aim; Radiofrequency Ablation (RFA) was reported as an effective treatment for localized primary and metastatic liver cancer. Although an enhanced CT scan depicts an ablated area as a hypoattenuated area without hepatic blood flow, histologic samples, fixed by formalin and stained by hematoxylin-eosin, obtained from the ablated area do not demonstrate tissue necrosis. The aim of this study is to evaluate liver tissue changes after RFA by light and electron microscopy using an experimental model. Methods; The normal liver of an anesthetized pig was coagulated by RF equipment (Radiotherapeutics Co., CA) after laparotomy using a needle electrode (LeVeen, CA). Immediately after, and one week after operation, the liver was removed and was examined by light and electron microscopy. Results; After the treatment with RFA, the area of the liver parenchyma surrounding the needle electrode become pale yellow, and was surrounded by a dark red marginal zone clearly separate from the normal liver parenchyma. In formalin fixed samples staining hematoxylin-eosin from the central pale yellow area did not show cell necrosis, and the structures of liver sinusoids, liver cell cord and the nuclei of hepatocytes were preserved at immediately after and one week after. After one week, granulomatous change with congestion of the outer layer was observed at the marginal zone of the ablated area. According to findings by electron microscope, the organelles containing mitochondria and the membrane of the nuclei of hepatocytes were destroyed and sinusoidal cells were fixed immediately after RFA. After one week, a lot of debris was observed in the enlarged sinusoid, and the destruction of the organelle of hepatocytes continued. Conclusions; Hepatocytes were fixed and damaged by RFA. This damage was not revealed by light microscopy, but was clearly shown by electron microscopy. 74

AIM: To compare the area of necrosis resulting from radiofrequency ablation (RFA) with that resulting from percutaneous microwave coagulation therapy (PMCT) in the treatment of patients with hepatocellular carcinoma (HCC). METHODS: Among 40 patients with solitary HCC, percutaneous RFA was used to treat 20 of the tumors (median tumor diameter 1.8 ern, range 1.2-3.2 em), and PMCT was used to treat the other 20 (median tumor diameter 1.3 em, range 0.8 to 2.0 em). The equipment for RFA was a IS-gauge probe with four retractable hooks and a RF generator (5OOPA, RITA Medical Systems). RFA was performed percutaneously in a single session with an initial power of lOW, increasing to 50 W in 10-W steps every 30 s until the target temperature of 80DC was attained. The temperature was then maintained at 80-1ooDC for 10 min. The equipment for PMCT was a 1.6-mm-diameter monopolar probe and a microwave generator (Microtaze, Nippon Shoji). PMCT was performed in a single session with a coagulation power of 60 W for 60 s and a dissociation current of 15 rnA for 15 s, One week after treatment, all the patients underwent enhanced CT. Completely unenhanced areas were measured as necrotic areas. RESULTS: The volume of necrosis was larger after RFA (11.8 :t 4.2 cnr') than after PMCT (5.1 :!: 1.7 cnr') (p