MATERIALS AND METHODS. We performed this study using eight pigs in experimental and control groups of four pigs each. Artificial ascites was produced before radiofrequency ablation to separate the liver from the diaphragm and the stomach in the experimental group. Using a 1-cm exposed internally cooled radiofrequency electrode for 5 minutes, we performed 74 hepatic ablations abutting the diaphragm and stomach. CT was performed on the day of the procedure and 7 days after ablation. The pigs were sacrificed, and necropsy was performed. We performed pathologic and CT examinations to compare the frequency and extent of thermal injury to the two organs.

RESULTS. The mean number of radiofrequency ablations in each pig was 9.3 (range, 6-12). The mean number of ablation zones adjoining the diaphragm was 5.5 (range, 3-8) and of zones contiguous with the stomach was 3.8 (range, 3-4). Thermal injury to the adjacent organs occurred more frequently in the control group than in the experimental group (p < 0.05). The major complications of diaphragmatic hernia and gastric perforation occurred only in the control group. No major complications were identified in the experimental group at necropsy. The sizes of the radiofrequency ablation zone of the liver did not differ between the two groups (p > 0.05). The mean diameters of the diaphragmatic and gastric lesions did differ (p < 0.05). Histopathologic examination revealed a significant difference in the depths of thermal injury in the two groups (p < 0.05).

CONCLUSION. Artificial ascites may be a simple and useful technique for reducing the frequency and severity of collateral thermal injury to the diaphragm and stomach during radiofrequency ablation of subcapsular hepatic tumors.

MATERIALS AND METHODS. During a 48-month period, 28 women (age range, 38-76 years) were referred to our department for retrograde exchange of a ureteral stent. The causes of urinary obstruction were tumor compression in 26 patients and benign fibrotic stricture in two patients. A large-diameter snare catheter (25-mm single loop or 18- to 35-mm triple loop) or a foreign body retrieval forceps (opening width, 11.3 mm) was used to grasp the bladder end of the stent under fluoroscopic guidance. The technique entailed replacement of a patent or occluded ureteral stent with a 0.035- or 0.018-inch guidewire with or without the aid of advancement of an angiographic sheath.

RESULTS. A total of 54 ureteral stents were exchanged with a snare catheter in 42 cases or a forceps in 12 cases. One stent misplaced too far up the ureter was replaced successfully through antegrade percutaneous nephrostomy. Ten occluded stents, including one single-J stent, were managed with a 0.018-inch guidewire in three cases, advancement of an angiographic sheath over the occluded stent into the ureter in five cases, and recannulation of the ureteral orifice with a guidewire in two cases. No complications of massive hemorrhage, ureter perforation, or infection were encountered.

CONCLUSION. With proper selection of a snare or forceps catheter, retrograde exchange of ureteral stents in women can be easily performed under fluoroscopic guidance with high technical success and a low complication rate.

MATERIALS AND METHODS. A previously recorded MRI examination from a custom-made phantom was loaded into the sonography system. The phantom contained spheres that were invisible to sonography and contained red dye. The red dye was visible in the biopsy if it was successful. The images were coregistered using structures visible on both sonography and MRI, and biopsies were taken. The biopsy procedure was continued until a biopsy was successful, and the number of needle passes and time spent were registered.

RESULTS. A total of 130 targets were hit. Ten minutes was used for loading the MRI data set and the coregistration; 94 of the 130 biopsies (72.3%) were successful at the first needle pass. The median number of needle passes until a successful biopsy was obtained was one (range, 1-7).

CONCLUSION. The described method was successful in obtaining an adequate sample in a phantom.