CT-Guided Sclerotherapy for Simple Renal Cysts Using 95% Ethanol and 20% Hypertonic Saline tion is considered necessary only when the cyst produces symptoms such as significant pain, an abdominal mass, hematuria, calyceal obstruction and/or hypertension secondary to renal segmental ischemia (5 8). Symptomatic renal cysts can be treated by percutaneous aspiration, with or without the injection of sclerosants, and by open or laparoscopic surgery (9 11). For the sympto- matic cases, treatment of the cyst is usually accompanied by remission of the symptoms (12). The decortication of peripheral and peripelvic cysts via laparoscopy is a safe, minimally invasive and effective treatment for sympto- matic renal cysts, and this method has a more durable response than that of open surgery (13), yet laproscopy is costly and it must be performed under general anesthesia. On the other hand, percutaneous aspiration and sclerother- apy are minimally invasive options. The data that’s currently available suggests that ethanol sclerotherapy for treating simple renal cysts has not yet been performed with a standardized method (12). There is no consensus in the scientific literature about the best way to treat simple renal cysts with sclerotherapy (8, 12, 14 16). There have been several studies that have focused on patients with cystic hydatid disease of the liver and who were treated with the percutaneous aspiration and injection of hypertonic saline (17 19). There have been no studies that have evaluated the use of hypertonic saline for the management of simple renal cysts. The aim of this study was to compare the efficacies of 95% ethanol and 20% hypertonic saline sclerotherapies that were performed during a single-session for the management of symptomatic simple renal cysts. MATERIALS AND METHODS Patients Written informed consent was obtained from each subject, and our Human Ethics Committee approved the study protocol. A prospective series of 74 consecutive patients (44 males and 30 females) who presented with symptomatic simple renal cyst were enrolled in this study to undergo sclerotherapy. These patients were seen between July 2002 and July 2005 at our hospital, and their average age was 57.6 8.1 years (age range: 40 72 years). The causes of referral to our department were flank pain in 67 patients, hydronephrosis and flank pain in two patients and examining the patient to reassure them due to the increasing cyst size in five patients. All the patients presented with flank pain and these symptoms were present for five to 13 months (mean 7 months) prior to admssion. For patients to be eligible for the study, their flank pain had to be non-colicky, ipsilateral to the cyst and Korean J Radiol 8(6), December 2007 not related to posture. Other causes of flank pain were excluded by the urologic evaluation that was done before referral to our department. The exclusion criteria were previous treatments for the renal cyst except for oral paracetamol or nonsteroidal anti-inflammatory analgesics, a communication between a simple renal cyst and the pelvicalyceal collecting system, abnormal renal function, polycystic or cystic dysplastic kidneys, those disorders that could possibly account for the presence of cysts (tuberous sclerosis or a previous malignancy), and peripelvic simple renal cysts. A simple renal cyst was diagnosed when it satisfied the criteria of Bosniak (20, 21). The diagnosis was obtained by abdominal US, and this was followed by a CT scan only when the visualization was inadequate on the US scanning performed by our study’s radiologists. CT scan was used for five patients because of the inadequate US imaging. The US criteria for the diagnosis of a simple renal cyst included 1) a spherical or ovoid shape, 2) the absence of internal echoes, 3) the presence of a thin, smooth wall that was separate from the surrounding parenchyma and 4) enhancement of the posterior wall that indicated there was transmission of US through the water-filled cyst with no calcification, no septa and no Doppler signals from within the cyst (22). The diagnosis of a simple renal cyst was made on the basis of the typical radiological findings with surrounding normal renal parenchyma, normal renal function and no associated systemic illnesses or disorders. The volume of the cyst was estimated by US with multiply- ing 3 diameters by the constant 0.5236 and also with considering that the cyst’s shape resembled a sphere. We used the following CT criteria for a renal mass that was called a Bosniak class I cyst: a uniform cyst density of no greater than 20 HU (the assigned density of water was 0 HU, and the cysts’ density ranged from 20 to +20 HU [23]), no enhancement of the mass on the CT images obtained after the administration of contrast medium (i.e., no increase in the Hounsfield units), and a round or oval shape with no perceptible wall (24). Procedures The sclerotherapy was performed under CT guidance on an outpatient basis. The patients were placed in the prone position and local anesthesia was achieved with 2% lidocaine hydrochloride that was applied to the puncture site. The patient was given nothing by mouth for 4 8 hours prior to the procedure. Prophylactic antibiotics were administered 60 minutes prior to the procedure and they were continued for at least 24 hours after the procedure. For all the patients, their coagulopathies were corrected prior to the procedure to decrease the chance of develop- 513