Nobuhisa Tajiri

Radiofrequency ablation of normal lungs after pulmonary artery embolization with use of degradable starch microspheres : Results in a porcine model

PURPOSE The present study was performed to evaluate the effect of pulmonary artery embolization on radiofrequency (RF) ablation of normal porcine lungs. MATERIALS AND METHODS RF ablation zones (n=34) were created in the normal lungs of five domestic pigs (five zones in each of the first two pigs and eight zones in each of the remaining three pigs) with an expandable multitined electrode with use of bilateral thoracotomy. RF ablation was performed without pulmonary artery embolization (group 1, n=8), immediately after embolization (group 2, n=11), 15 minutes after embolization (group 3, n=7), and 30 minutes after embolization (group 4, n=8) with degradable starch microspheres. Among them, 12 ablation zones were excluded from this study because they were considerably limited by the presence of the pleura or large bronchi. The remaining 22 zones were included (n=7, n=5, n=4, and n=6 in groups 1, 2, 3, and 4, respectively). Coagulation necrosis volumes in the ablation zones were measured and compared among the groups. RESULTS Coagulation necrosis volumes were 0.9+/-0.5 cm3, 2.1+/-0.4 cm3, 2.1+/-1.0 cm3, and 1.9+/-0.6 cm3 in groups 1, 2, 3, and 4, respectively. Groups 2-4 showed significantly larger coagulation volumes than group 1 (P=.012, P=.023, and P=.010 in groups 2, 3, and 4, respectively). CONCLUSION Pulmonary artery embolization contributed to larger volumes of coagulation necrosis after RF ablation of normal lungs.

Sloughing of Intraductal Tumor Thrombus of Hepatocellular Carcinoma after Transcatheter Chemoembolization Causing Obstructive Jaundice and Acute Pancreatitis

Editor: A 69-year-old man with liver cirrhosis as a result of hepatitis C virus was admitted to our department. He had a history of surgical resection of hepatocellular carcinoma (HCC) 6 years earlier. Thereafter, two new foci of HCC developed and each was treated with a combination of transcatheter chemoembolization (TACE) and radiofrequency (RF) ablation. At the current admission, another tumor with a diameter of 1.7 cm had developed in the periphery of the medial segment. The patient was admitted in anticipation of RF ablation of this tumor under computed tomographic (CT) fluoroscopic guidance. Our institution does not require an institutional review board approval for retrospective reports such as this. Plain CT images for targeting immediately before RF ablation showed dilation of the intrahepatic bile duct in the left lobe and soft tissue density within the expanded left hepatic duct as the causes of biliary dilation. Because we speculated that cholangitis may possibly develop after RF ablation of the liver with biliary dilation, the scheduled RF ablation was cancelled. Laboratory data obtained the same day showed serum total bilirubin level of 2.18 mg/dL (normal range, 0.33–1.28 mg/dL). Dynamic CT and magnetic resonance imaging were subsequently performed to evaluate the mass within the left hepatic duct. In addition to the tumor in the medial segment, a hypervascular tumor 3.2 cm in diameter directly adjacent to the left hepatic duct was demonstrated in the lateral segment. The mass within the left hepatic duct did not enhance after contrast medium administration, likely indicating hemobilia caused by hemorrhage from the tumor in the lateral segment invading into the left hepatic duct. Six days later, the serum total bilirubin level returned to the previous level and repeat CT images showed that biliary dilation substantially improved, accompanied by spontaneous resolution of hemobilia. Because of limited hepatic function, the patient was not a suitable candidate for surgical resection. RF ablation was also inappropriate because the tumor in the lateral segment involved the left hepatic duct. Therefore, it was selected to perform TACE. On hepatic arteriography, the tumor in the medial segment was supplied by the medial segmental artery and the tumor in the lateral segment was supplied mainly by a branch of the lateral segmental artery. To reduce the possible risk of hepatic failure, hepatic abscess, and biloma after TACE, we performed superselective embolization of each tumor. A microcatheter (Renegade; Boston Scientific, Natick, MA) was selectively introduced into the arteries supplying each tumor, and TACE was performed with injection of a mixture of 1.2 mL iodized oil (Lipiodol; Laboratoire Andre Guerbet, Aulnay-sous-Bois, France) and 12 mg epirubicin (Kyowa-Hakko, Tokyo, Japan), followed by gelatin sponge particles, for the tumor in the medial segment. The tumor in the lateral segment was then treated in the same fashion, but with 0.8 mL iodized oil and 8 mg epirubicin before administration of gelatin sponge particles. On plain CT images immediately after TACE, part of the iodized oil accumulation in the tumor in the lateral segment seemed to protrude into the left hepatic duct (Figure, part a) and dense iodized oil accumulation was seen in the entire tumor in the medial segment (Figure, part a). No immediate complications occurred and the patient was discharged 10 days after TACE. Eighteen days after TACE, the patient returned to our department because with jaundice and severe back pain. Laboratory data on admission showed markedly increased serum total bilirubin and amylase levels of 8.03 mg/dL and 1,000 IU/L (normal range, 38–125 IU/L), respectively. On dynamic CT images, marked dilation of the intrahepatic and common bile duct was demonstrated. Iodized oil accumulation within the left hepatic duct was no longer visible (Figure, part b), and at the bottom of the common bile duct was a high-density deposit (Figure, part c), which was believed to represent sloughed tumor with iodized oil accumulation and the cause of biliary obstruction. Subsequent endoscopic examination revealed the oral protrusion markedly expanding and the sloughed tumor obstructing the ampulla of Vater and protruding into the lumen of the duodenum (Figure, part d). Endoscopic sphincterotomy was then performed and two pieces of tumor migrated into the duodenum. Immediately after the endoscopic therapy, the patient’s back pain resolved. The serum amylase level decreased promptly and returned to normal level 2 days later. The serum total bilirubin level gradually decreased and returned to baseline level 1 month after the endoscopic therapy. Although tumor thrombus into the portal vein is a common feature in the development of HCC, intraductal tumor involvement is not as widely recognized. Kojiro et al (1) reported 24 cases of HCC with prominent tumor growth in the bile duct among 259 autopsy and surgical cases, with a prevalence of approximately 9%. Intraductal tumor is usually associated with large HCC with volumes of more than 40% of the whole liver (1) and associated with varying degree of jaundice at admission or during the course of the disease (1–3). HCC with intraductal tumor involvement is DOI: 10.1097/01.RVI.0000200055.74822.ED Letters to the Editor

Radiofrequency Ablation of Small Lung Metastases by a Single Application of a 2-cm Expandable Electrode: Determination of Favorable Responders

PURPOSE To determine which lung metastases are most likely to be treated effectively with a single radiofrequency (RF) application (defined as two separate applications of RF energy at a single electrode position) with a multitined expandable electrode with arrays 2 cm in diameter. MATERIALS AND METHODS The authors retrospectively evaluated 88 lung metastases (mean long-axis diameter, 0.9 cm) in 36 patients (20 men and 16 women; mean age, 57 years) treated with a single RF application with a multitined expandable electrode with arrays 2 cm in diameter. Based on follow-up computed tomographic examinations, the technique effectiveness rates were estimated with Kaplan-Meier analysis. Multiple variables were analyzed with the log-rank test to determine risk factors for local progression. Then, the technique effectiveness rates were again estimated when considering only metastases without risk factors and compared with those of other tumors. RESULTS The median follow-up period was 13.2 months (range, 6.0-24.7 months). Tumor size greater than 1.0 cm (P = .033) and contact with the bronchus with an inner diameter of at least 2 mm (P = .047) were the significant risk factors for local progression. The technique effectiveness rates for metastases 1.0 cm or smaller that were not in contact with the bronchus (n = 59) were 96% at 1 year and at 2 years; those rates were significantly (P = .010) higher than those in other tumors (n = 29). CONCLUSIONS A single RF application with a multitined expandable electrode with arrays 2 cm in diameter is most likely to suffice in small (<or=1 cm) lung metastases not in contact with a bronchus.