CT-Guided Sclerotherapy for Simple Renal Cysts: Value of Ethanol Concentration Monitoring

Objective: The aim of our study was to evaluate the differences between sclerotherapy with and without ethanol concentration monitoring for the treatment of simple renal cysts. Materials and Methods: Sixty-seven patients with 70 simple renal cysts were randomly assigned to two groups in a 12-month prospective controlled trial. One group (group A) was treated with computed tomography (CT)-guided sclerotherapy without ethanol concentration monitoring (33 patients with 35 cysts), whereas the other group (group B) had ethanol concentration monitoring (34 patients with 35 cysts) during the procedure. Treatment outcomes between the two groups were compared 12 months later with follow-up ultrasound examination. Results: After the 12-month follow-up period, the overall success rate was 74.3% in group A and 94.3% in group B (p = 0.022). The mean cyst size before and after treatment was $8.6{\pm}2.0cm$ and $2.3{\pm}2.9cm$, respectively, in group A, and $8.4{\pm}1.7cm$ and $0.8{\pm}1.9cm$, respectively, in group B. The final size of the cysts in group B was significantly smaller than that in group A (p = 0.015). The likelihood of treatment with ethanol concentration monitoring being successful was approximately 16 times higher than without ethanol concentration monitoring (p = 0.026; odds ratio = 15.7; 95% confidence interval: 1.38-179.49). There were no major complications in either group. Conclusion: Monitoring of Hounsfield units (HU) of ethanol by CT is an effective method in the treatment of simple renal cysts with ethanol sclerotherapy. The ethanol sclerotherapy procedure can be terminated at the point of clear fluid aspiration because the HU (-190) of CT scan corresponds to it.