Contrast enhanced ultrasound diagnosis of complex cystic renal mass: Interobserver variability based on different Bosniak classification systems

The diagnostic value of Bosniak classification based on contrast enhanced ultrasound (CEUS) on complex cystic renal mass (CRM) was compared among different observers. From 2012 to 2022, 212 complex CRMs, confirmed by pathology or at least 1-year imaging follow-up, were enrolled. The CEUS images of CRM were retrospectively analyzed by two reviewers with different experience in kidney CEUS examination, and each lesion was given the categorizations according the Bosniak ver. 2015 and ver. 2019, respectively. There was good inter-observer agreement (k = 0.689; p < 0.05) for Bosniak ver. 2019. With Bosniak ver. 2019, senior and junior reviewer correctly classified 44 (83.02%), 40 (75.47%) benign lesions as low grade (Ⅰ ∼ ⅡF), and 94 (94.95%), 80 (80.81%) malignant tumors as high grade (Ⅲ or Ⅳ), respectively. Meanwhile, the combination of Bosniak 2019 and senior reviewer demonstrated the highest area under the receiver operating characteristic curve (Az: 0.875, all p < 0.05) than other groups, with the highest specificity (81.10%) and sensitivity (93.90%) among all the groups (95% CI, 0.807–0.943; p < 0.05), respectively. Overall, the senior reviewer combined with Bosniak ver. 2019 was the best choice for the diagnosis of complex CRM.