Hong Eo

Hepatic Radiofrequency Ablation Using Multiple Probes: Ex Vivo and In Vivo Comparative Studies of Monopolar versus Multipolar Modes

Objective We wanted to compare the efficiency of multipolar radiofrequency ablation (RFA) using three perfused-cooled electrodes with multiple overlapping and simultaneous monopolar techniques for creating an ablation zone in ex vivo bovine livers and in in vivo porcine livers. Materials and Methods In the ex vivo experiments, we used a 200 W generator (Valleylab, CC-3 model) and three perfused-cooled electrodes or internally cooled electrodes to create 30 coagulation zones by performing consecutive monopolar RFA (group A, n = 10), simultaneous monopolar RFA (group B, n = 10) or multipolar RFA (group C, n = 10) in explanted bovine livers. In the consecutive mode, three ablation spheres were created by sequentially applying 150 watts radiofrequency (RF) energy to the internally cooled electrodes for 12 minutes each for a total of 36 minutes. In the simultaneous monopolar and multipolar modes, RF energy was concurrently applied to the three perfused-cooled electrodes for 20 minutes at 150 watt with instillation of 6% hypertonic saline at 2 mL/min. During RFA, we measured the temperatures of the treated area at its center. The changes in impedance, the current and liver temperature during RFA, as well as the dimensions of the thermal ablation zones, were compared among the three groups. In the in vivo experiments, three coagulations were created by performing multipolar RFA in a pig via laparotomy with using same parameter as the ex vivo study. Results In the ex vivo experiments, the impedance was gradually decreased during the RFA in groups B and C, but in group A, the impedance was increased during RFA and this induced activation by the pulsed RF technique. In groups A, B and C, the mean final-temperature values were 80±10℃, 69±18℃and 79±12℃, respectively (p < 0.05). The multipolar mode created a larger volume of ablation than did the other modes: 37.6±4.0 cm3 (group A); 44.9±12.7 cm3 (group B); and 78.9±6.9 cm3 (group C) (p < 0.05). In the in vivo experiment, the pig well tolerated the RFA procedure and no major complications occurred during the 4 days of the follow-up period. The mean volume of coagulations produced by multipolar RFA in the pig liver was 60.5±17.9 cm3. Conclusion For the multiple probe RFA, the multipolar mode with hypertonic saline instillation was more efficient in generating larger areas of thermal ablation than either the consecutive or simultaneous monopolar modes.

Endobronchial metastasis from renal cell carcinoma: CT findings in four patients

PURPOSE To describe the CT findings of an endobronchial metastasis from a renal cell carcinoma (RCC). MATERIALS AND METHODS The CT findings and clinical features of a histologically proven endobronchial metastasis from a RCC in four patients (three male, one female; age range, 64-80 years; mean age, 69 years) were reviewed retrospectively. The location of the metastasis in the airway, shape, the degree of tumor enhancement, and the associated pulmonary parenchymal abnormalities were analyzed. RESULTS The histological subtype of the endobronchial metastases from the RCC was conventional in all cases. The tumors were located at the lobar (n = 1), both the lobar and segmental (n = 2), or the segmental (n = 1) bronchus. On the CT scan, the tumors were polypoid (n = 1), had a glove-finger appearance (n = 2), and exhibited branching in the airways and bronchial wall thickening (n = 1). The endobronchial metastasis from the RCC showed very high attenuation (84-128 HU), and strong enhancement (51.6-93.3 HU) on the contrast-enhanced CT images. The lung parenchymal lesions that had reticular opacities and ground glass opacities (n = 3). CONCLUSIONS An endobronchial metastasis from a RCC appears as a strong-enhancing mass or bronchial wall thickening, accompanied by reticular opacities and ground glass opacities.

Serial CT Findings of Paragonimus Infested Dogs and the Micro-CT Findings of the Worm Cysts

Objective To investigate the serial CT findings of Paragonimus westermani infected dogs and the microscopic structures of the worm cysts using Micro-CT. Materials and Methods This study was approved by the committee on animal research at our institution. Fifteen dogs infected with P. westermani underwent serial contrast-enhanced CT scans at pre-infection, after 10 days of infection, and monthly thereafter until six months for determining the radiologic-pathologic correlation. Three dogs (one dog each time) were sacrificed at 1, 3 and 6 months, respectively. After fixation of the lungs, both multi-detector CT and Micro-CT were performed for examining the worm cysts. Results The initial findings were pleural effusion and/or subpleural ground-glass opacities or linear opacities at day 10. At day 30, subpleural and peribronchial nodules appeared with hydropneumothorax and abdominal or chest wall air bubbles. Cavitary change and bronchial dilatation began to be seen on CT scan at day 30 and this was mostly seen together with mediastinal lymphadenopathy at day 60. Thereafter, subpleural ground-glass opacities and nodules with or without cavitary changes were persistently observed until day 180. After cavitary change of the nodules, the migratory features of the subpleural or peribronchial nodules were seen on all the serial CT scans. Micro-CT showed that the cyst wall contained dilated interconnected tubular structures, which had communications with the cavity and the adjacent distal bronchus. Conclusion The CT findings of paragonimiasis depend on the migratory stage of the worms. The worm cyst can have numerous interconnected tubular channels within its own wall and these channels have connections with the cavity and the adjacent distal bronchus.