Minimizing central bile duct injury during radiofrequency ablation: use of intraductal chilled saline perfusion--initial observations from a study in pigs.

PURPOSE: To determine whether intraductal perfusion with chilled saline reduces thermal injury to bile ducts during radiofrequency (RF) ablation. MATERIALS AND METHODS: In swine, anesthesia was induced and the common bile duct was surgically cannulated with a pediatric feeding tube. RF thermal lesions were created adjacent to bile ducts by using an expandable-hook 2-cm RF electrode and 90-W generator. In three pigs, chilled saline was perfused through the ducts at 1.5 L/h (26 mL/min), and in another pig, room-temperature saline was perfused at the same rate. In three pigs (control group), RF lesions were created without perfusion. After 48 hours, animals were sacrificed. Periductal sections from all animals were reviewed by a liver pathologist. The degree of injury to biliary epithelium and subepithelial glands was assessed on a scale of 0%-100%. Significance of differences between degrees of injury was assessed with the Mann-Whitney test. RESULTS: In the control group, there was a mean of 100% injury to biliary ductal epithelium and 99.3% to subepithelial ductal glands. In the room-temperature saline group, there was a mean of 100% biliary epithelial injury and 84.4% glandular injury. In the chilled saline group, there was a mean of 52.9% ductal epithelial injury and 12.1% subepithelial glandular injury. In comparison with the control group, there was significantly less (P <.05) thermal injury to biliary epithelium in the chilled saline group and to subepithelial glands in both the room-temperature and chilled saline perfusion groups. CONCLUSION: RF-induced bile duct injury may be decreased significantly with an intraductal infusion of chilled saline.

Minimizing diaphragmatic injury during radiofrequency ablation: efficacy of intraabdominal carbon dioxide insufflation.

OBJECTIVE: The purpose of our study was to determine whether intraperitoneal insufflation of carbon dioxide (CO(2)) reduces adjacent diaphragmatic injury. MATERIALS AND METHODS: In seven pigs under anesthesia, a 17-gauge percutaneous insufflation needle was inserted in the infraumbilical midline using a standard insufflator. Three to six liters of CO(2) was infused into the peritoneal space to achieve at least a 1-cm separation between the liver and the diaphragm and maintained by a pressure of 8-10 mm Hg. Seven control lesions in six historical controls were used. In addition, five lesions were created in one animal from this cohort who served as a control. Superficial areas of liver separated from diaphragm were fluoroscopically targeted for radiofrequency ablation, and several 2-cm-diameter radiofrequency lesions were generated. The pigs were sacrificed at 48 hr, and at laparotomy, the liver surface was inspected and sectioned to select lesions with centers within 1 cm of the surface. The thermal injury to the corresponding adjacent diaphragm was examined to determine the depth of injury. Diaphragmatic injury was graded on a scale from 0 to III (0, no injury; I, mild injury to one-third thickness; II, moderate injury to two-thirds thickness; III, severe injury to full thickness.) RESULTS: Of 72 total lesions created, 60 had centers less than 1 cm from the liver surface (i.e., superficial) at laparotomy. Of these 60 lesions, 55 caused no significant diaphragmatic injury, two caused grade I injury and three caused grade III injury. In comparison, seven of seven historic superficial control lesions and five of five superficial radiofrequency control lesions from the current cohort caused grade III injury. Superficial radiofrequency lesions created after intraperitoneal CO(2) insufflation caused significantly less (p < 0.01) diaphragmatic injury. CONCLUSION: We have shown that in pigs, intraperitoneal CO(2) insufflation helped significantly reduce severe diaphragmatic injury when superficial hepatic radiofrequency ablation was performed.

Influence of large peritumoral vessels on outcome of radiofrequency ablation of liver tumors.

PURPOSE: The effect of large vessels (>/=3 mm) contiguous to hepatic tumors was evaluated with respect to clinical tumor recurrence rates after radiofrequency (RF) ablation. MATERIALS AND METHODS: The first 105 malignant liver tumors treated by RF ablation therapy at our institution with pathologic analysis or a minimum of 6 months of clinical follow-up were reviewed. The original pretreatment imaging studies were reviewed by a radiologist who was blinded to the cases, and, based on lesion contiguity to vessels of at least 3 mm, the lesions were categorized as perivascular or nonperivascular. Treatment outcomes with respect to local tumor recurrence between these two groups were then compared. Logistic regression analysis was performed to take into account other variables and to determine whether this categorization was an independent predictor of treatment outcome. RESULTS: There were 74 nonperivascular tumors and 31 perivascular tumors. Mean tumor size was 2.4 cm and mean follow-up was 11.3 months. Residual or locally recurrent tumors were documented in 20 of 105 cases (19%). In the nonperivascular group, five of 74 (7%) had either incompletely treated tumor (manifested within 6 months) or local recurrence beyond 6 months. In the perivascular group, 15 of 31 (48%) had incompletely treated or locally recurrent tumor (P <.001). Subanalysis of lesion size (61 tumors 4 cm), tumor type (40 hepatocellular carcinomas, 48 colorectal metastases, and 17 other metastases), access (53 intraoperative, 52 percutaneous), and RF device (45 Radiotherapeutics electrodes, 18 Rita electrodes, and 42 Radionics electrodes) showed similar results. Multivariate logistic regression analysis showed that presence or absence of a large peritumoral vessel is an independent, and the dominant, predictor of treatment outcome. CONCLUSION: The presence of vessels at least 3 mm in size contiguous to hepatic tumors is a strong independent predictor of incomplete tumor destruction by RF ablation. Modified ablation strategies should be considered to improve destruction of these tumors.

Progression of coronary artery calcification in patients taking alendronate for osteoporosis.

RATIONALE AND OBJECTIVES: As with their actions on bone, bisphosphonates may play a role in coronary artery calcification (CAC) by inhibiting calcium resorption from plaque. The objective of this study was to determine whether the osteoporosis treatment agent alendronate accelerates the rate of CAC. MATERIALS AND METHODS: The study was a pilot comparative analysis of 56 alendronate-treated patients with osteoporosis compared with 56 control subjects matched for age, sex, risk factors, and CAC scores and with a reference cohort that included 213 control subjects. Patients received alendronate sodium (10 mg daily) for a mean of 24 months and underwent annual assessment of CAC with electron-beam computed tomography and bone mineral density with dual x-ray absorptiometry. The principal outcome measure was the rate of change in CAC score in patients and control populations. RESULTS: There was significant progression of CAC in both alendronate-treated and matched-control groups (paired t test, P = .004 and .006, respectively) but no difference in the rates of CAC progression between the alendronate-treated patients and either the matched or reference control cohort. CONCLUSIONS: This small pilot study indicates that oral alendronate administration does not accelerate the rate of CAC, but a larger cohort should be studied to confirm these findings.