Effectiveness of impedance monitoring during radiofrequency ablation for predicting popping

AIM： To retrospectively evaluate the effectiveness of impedance monitoring for predicting popping during radiofrequency ablation （RFA） using internally cooled electrodes. METHODS： We reviewed 140 patients （94 males, 46 females; age range 73.0 ＋ 11.1 year） who underwent RFA between February 2006 and November 2008 with a modified protocol using a limited power delivery rather than a conventional one to avoid popping. All the patients provided their written informed consent, and the study was approved by the institutional review board. Intraprocedural impedances were measured for the study subjects, and the tumors were classified into three types according to the characteristics of their impedance curves： increasing, flat, or decreasing. The tumors were further sorted into seven subtypes （A-G） depending on the curvature of the impedance curve＇ s increase or decrease. Relative popping rates were determined for the three types and seven subtypes. A chi-square test was performed to estimate statistical significance.RESULTS： A total of 148 nodules treated by RFA were analyzed. The study samples included 132 nodules of hepatocellular carcinoma, 14 nodules of metastatic liver cancer, and two nodules of intrahepatic cholangio- carcinoma. The numbers of nodules with each imped- ance curve type were as follows： 37 increasing-type nodules, 43 fiat-type nodules, and 68 decreasing-type nodules. Popping occurrence rates were 24.3%, 46.5% and 64.7%, respectively. Flat-type nodules exhibited a significantly higher rate of popping compared to increasing-type nodules （P = 0.039）. Decreasing-type nodules exhibited a significantly higher rate of popping compared to increasing-type nodules （P 〈 0.0001）. No- tably, nodules that showed a sharp decrease in imped- ance in the latter ablation period （subtype E） exhibited a significantly higher rate of popping compared to other subtypes. CONCLUSION： Intraprocedural impedance monitoring can be a useful tool to predict the occurrence of pop- ping during liver tumor RFA performed with internally cooled electrodes.

Comparison of percutaneous transhepatic portal vein embolization and unilateral portal vein ligation

AIM： To compare the effect of percutaneous transhepatic portal vein embolization （PTPE） and unilateral portal vein ligation （PVL） on hepatic hemodynamics and right hepatic lobe （RHL） atrophy.METHODS： Between March 2005 and March 2009, 13 cases were selected for PTPE （n = 9） and PVL （n = 4） in the RHL. The PTPE group included hilar bile duct carcinoma （n = 2）, intrahepatic cholangiocarcinoma （n = 2）, hepatocellular carcinoma （n = 2） and liver metastasis （n = 3）. The PVL group included hepatocellular carcinoma （n = 2） and liver metastasis （n = 2）. In addition, observation of postoperative hepatic hemodynamics obtained from computed tomography and Doppler ultrasonography was compared between the two groups.RESULTS： Mean ages in the two groups were 58.9 ± 2.9 years （PVL group） vs 69.7 ±3.2 years （PTPE group）, which was a significant difference （P = 0.0002）. Among the indicators of liver function, including serum albumin, serum bilirubin, aspartate aminotransferase, alanine aminotransferase, platelets and indocyanine green retention rate at 15 min, no significant differ- ences were observed between the two groups. Preop-erative RHL volumes in the PTPE and PVL groups were estimated to be 804.9 ±181.1 mL and 813.3 4±129.7 mL, respectively, with volume rates of 68.9% ± 2.8% and 69.2% ±4.2%, respectively. There were no significant differences in RHL volumes （P = 0.83） and RHL volume rates （P = 0.94）, respectively. At 1 mo after PTPE or PVL, postoperative RHL volumes in the PTPE and PVL groups were estimated to be 638.4±153.6 mL and 749.8 ± 121.9 mL, respectively, with no significant difference （P = 0.14）. Postoperative RHL volume rates in the PTPE and PVL groups were estimated to be 54.6% ± 4.2% and 63.7% ± 3.9%, respectively, which was a significant difference （P = 0.0056）. At 1 mo after the operation, the liver volume atrophy rate was 14.3% ± 2.3% in the PTPE group and 5.4%± 1.6% in the PVL group, which was a significant difference （P = 0.0061）.CONCLUSION： PTPE is a more effective procedure than PVL because PTPE is able to occlude completely the portal branch throughout the right peripheral vein.

Simultaneous bile duct and portal venous branch ligation in two-stage hepatectomy

Hepatectomy is an effective surgical treatment for multiple bilobar liver metastases from colon cancer;however,one of the primary obstacles to completing surgical resection for these cases is an insufficient volume of the future remnant liver,which may cause postoperative liver failure.To induce atrophy of the unilateral lobe and hypertrophy of the future remnant liver,procedures to occlude the portal vein have been conventionally used prior to major hepatectomy.We report a case of a 50-year-old woman in whom two-stage hepatectomy was performed in combination with intraoperative ligation of the portal vein and the bile duct of the right hepatic lobe.This procedure was designed to promote the atrophic effect on the right hepatic lobe more effectively than the conventional technique,and to the best of our knowledge,it was used for the first time in the present case.Despite successful induction of liver volume shift as well as the following procedure,the patient died of subsequent liver failure after developing recurrent tumors.We discuss the first case in which simultaneous ligation of the portal vein and the biliary system was successfully applied as part of the first step of two-stage hepatectomy.

Optimal combination of radiofrequency ablation with chemoradiotherapy for locally advanced pancreatic cancer

Problems have been reported in the treatment of pancreatic cancer with radiofrequency ablation(RFA), such as the friability of the organ itself. This report presents possible solutions to such problems. Although our patient suffered from locally advanced unresectable pancreatic cancer, she remained well at 18 mo after RFA with no evidence of recurrence. To ameliorate the side effects of RFA, after a palliative bypass procedure, the subject was treated with combined radiotherapy and chemotherapy. After this regimen had been administered, a contrast-enhanced computed tomography scan confirmed that RFA is a viable approach to the treatment of pancreatic cancer as the chemoradiotherapy had resulted in marked tumor shrinkage and pancreatic fibrosis; i.e., sufficient tumor ablation was achieved without serious RFA-related complications, such as pancreatitis or pancreatic fistulae. The present case suggests that RFA combined with preceding chemoradiotherapy is safe and effective for the palliative treatment of locally advanced pancreatic cancer.