CT OF CYSTIC RENAL MASSES - ANALYSIS OF DIAGNOSTIC PERFORMANCE AND INTEROBSERVER VARIATION

OBJECTIVE. Our objective was to assess the clinical usefulness and int erobserver variability of the Bosniak classification scheme for charac terizing a series of pathologically proven cystic renal lesions imaged with CT. MATERIALS AND METHODS. Seventy pathologically proven cystic renal masses (38 benign, 32 malignant) in 46 patients were reviewed in dependently by three radiologists. The cystic masses were categorized by each reviewer according to both the Bosniak classification and the receiver operating characteristic (ROC) analysis. Both the individual results for each reader and the pooled results for all three readers w ere analyzed. Interobserver agreement and discordance in classifying l esions as Bosniak categories I-II or III-IV were assessed. RESULTS. Th e distribution of the 70 lesions (based on the average of the three re aders) was 22 Bosniak I (0% malignant), eight Bosniak II (13% malignan t), 11 Bosniak III (45% malignant), and 29 Bosniak IV (90% malignant). All readers agreed on the Bosniak classification in 59%, or 41 of the 70 lesions (I, 17; II, one; III, four; and IV, 19). Eleven (16%) of t he 70 lesions were classified as Bosniak I or II by one reader and as Bosniak In or TV by at least one other reader, The area under the curv e for the pooled ROC analysis was calculated to be 0.957. Individual r eader values ranged from 0.914 to 0.981. The sensitivities, specificit ies, and accuracies for the three readers ranged from 94% to 100%, 71% to 92%, and 84% to 93%. Assessment of interobserver variability by ka ppa analysis yielded scores of .571 and .477 for the Bosniak and ROC a nalyses, respectively. CONCLUSION. Overall, the Bosniak classification scheme is useful for evaluating renal masses; however, interobserver variation in distinguishing Bosniak II and Bosniak III lesions may pre sent difficulties in recommending surgical Versus conservative managem ent.