CLINICAL STUDY Analysis of the RENAL and mRENAL Scores and the Relative Importance of Their Components in the Prediction of Complications and Local Progression after Percutaneous Renal Cryoablation Samdeep K. Mouli, MD, MS, Joseph L. McDevitt, MD, MBA, Yu-Kai Su, MD, Ann B. Ragin, PhD, Yi Gao, PhD, Albert A. Nemcek, Jr, MD, Robert J. Lewandowski, MD, Riad Salem, MD, MBA, and Kent T. Sato, MD ABSTRACT Purpose: To determine if modified RENAL (mRENAL) score and its individual components have superior predictive value relative to the RENAL nephrometry score in prediction of complications and recurrence after percutaneous renal cryoablation. Materials and Methods: Primary masses treated with CT–guided percutaneous renal cryoablation between June 2007 and May 2016 were retrospectively reviewed. RENAL and mRENAL scores were used to stratify masses into low, medium, and high complexity tertiles. Complications were characterized by SIR criteria. Predictors of complications and local progression were analyzed using multivariate logistic regression and Kaplan-Meier analysis. Results: There were 95 renal cryoablation procedures in 86 patients. Of ablations, 89 had at least 1 follow-up imaging study, with median follow-up of 29 months. There were 11 (12.4%) complications, including 5 (6.5%) major complications. Mass complexity, as measured by mRENAL complexity tertile, was associated with increased risk of complications on multivariate analysis (P ¼ .045). Endophytic location was the only individual ordinal component of the RENAL and mRENAL scores associated with complications (P ¼ .021). Local progression occurred in 7 (8.3%) masses. Complexity as measured by either scoring system was not associated with local progression. Only diameter 4 3 cm was associated with increased risk of local progression (hazard ratio ¼ 9.9, 95% confidence interval ¼ 2.1–45, P ¼ .003). Conclusions: mRENAL score was predictive of complications and tumor size was predictive of recurrence. Use of mRENAL score for complications and tumor size for recurrence should allow for simpler risk stratification and more accurate patient counseling. ABBREVIATION mRENAL = modified RENAL Incidental detection of small renal masses has increased in recent decades (1). Although partial nephrectomy is the definitive therapy, percutaneous renal cryoablation is safe and effective for small renal masses (2–5), compar- ing favorably in efficacy with laparoscopic cryoablation (4,5) and partial nephrectomy (6), with significant cost advantage (7). However, it is important to properly select patients to maximize efficacy and minimize morbidity. The RENAL nephrometry score, developed for surgical resection, is a standardized method for characterizing the complexity of renal masses (8) that has been shown in some studies to predict treatment success (9,10) and complications (9–11). However, there From the Department of Radiology (S.K.M., J.L.M., Y.-K.S., A.B.R., A.A.N., R.J.L., R.S., K.T.S.), Northwestern University Feinberg School of Medicine, 676 North St. Clair Street, Ste 800, Chicago, IL 60611; and Department of Statistics (Y.G.), Northwestern University, Chicago, Illinois. Received October 14, 2016; final revision received December 25, 2016; accepted December 26, 2016. Address correspondence to J.L.M.; E-mail: josephlmcdevitt@ icloud.com None of the authors have identified a conflict of interest. Current affiliation of J.L.M.: Department of Radiology, UT Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390. & SIR, 2016 J Vasc Interv Radiol 2017; XX:]]]–]]] http://dx.doi.org/10.1016/j.jvir.2016.12.1224