CT-Guided Sclerotherapy for Simple Renal Cysts Using 95% Ethanol and 20% Hypertonic Saline systemic side effects. Before removal of the ethanol or hypertonic saline, the patients were placed in the prone, supine, and lateral decubitus positions for a minimum of 5 minutes each to allow adequate contact of the ethanol with all areas of the cyst wall (25). The ethanol or hypertonic saline was then removed and the pigtail catheter was removed (Fig. 1D). Sclerotherapy was deemed as techni- cally successful if the procedure went uneventfully without any complication. Follow-up Evaluations that included asking questions about residual pain, a physical examination and routine abdominal US performed by the same radiologist who performed the puncture, were done at one, three and six months after treatment, with special attention being given to the segment of the kidney in which the treated cyst had been located. CT imaging after sclerotherapy was required for three patients because of inadequate US visualization of the kidneys. Six months after sclerotherapy with performing follow- up clinical and US evaluations, the treatment success was evaluated according to regression of the cyst and the improvement of the previous clinical symptoms and findings. Disappearance of the renal cyst with the absence of the previous clinical symptoms and findings was consid- ered as complete regression. A reduction in the volume of the cyst of more than half the volume before sclerotherapy was performed when there was partial improvement of the previous clinical symptoms and the findings were consid- ered as partial regression. Treatment was accepted to have failed when the cyst recurred to more than half the previous volume before sclerotherapy and/or when no there was improvement of the previous clinical symptoms and findings. After failure of sclerotherapy, the patients underwent sclerotherapy again with the same sclerosant for up to three times if they had persistent flank pain. Statistical Analysis The volume of the cysts and the presence of complete or partial regression and failure at the follow-up were all recorded. The presence of pain during filling the cyst with sclerosant and also the presence of pain after the procedure were also recorded. The cystic volumes of the ethanol and hypertonic saline groups were analyzed with the Mann-Whitney U test. The complete regression and failure ratios of the ethanol and hypertonic saline groups were analyzed with the 2 test. RESULTS The sclerotherapy was technically successful in all but two patients, and these patients were excluded because a communication existed between their simple renal cyst and the pelvicalyceal collecting system. Of the remaining 72 patients, 36 patients in the ethanol group received sclerotherapy with 95% ethanol, and 36 patients in the hypertonic saline group underwent sclerotherapy with 20% hypertonic saline. There were no major complications in the study groups and no signs of intoxication with the use of sclerosants. There were no significant differences between the types and volumes of the administered and removed sclerosants in the ethanol and hypertonic saline groups (p = 0.311 and p = 0.471, respectively). The cytology examination of the fluid was negative for neoplastic cells in all the patients, and biochemical analysis of the cystic fluid showed findings similar to those of the corresponding plasma. Figure 2 presents the volume of the simple renal cysts in the ethanol and hypertonic saline groups. There was no significant difference between the ethanol and hypertonic Fig. 2. Scatter dot plot with median line graphics of the volume of the simple renal cysts in the ethanol and hypertonic saline groups. There was no significant difference of the cyst volume between the study groups (p = 0.995). Korean J Radiol 8(6), December 2007 515