Neoadjuvant Chemotherapy VI-RADS Scores for Assessing Muscle-invasive Bladder Cancer Response to Neoadjuvant Immunotherapy with Multiparametric MRI.

Background An accurate method of assessing the response of muscle-invasive bladder cancer (MIBC) to neoadjuvant treatment is needed for selecting candidates for bladder-sparing strategies. Purpose To evaluate the diagnostic accuracy and reproducibility of neoadjuvant chemotherapy Vesical Imaging Reporting and Data System (nacVI-RADS) scores and posttreatment Vesical Imaging Reporting and Data System (VI-RADS) scores when assessing MIBC response to neoadjuvant immunotherapy with multiparametric MRI (mpMRI). Materials and Methods A retrospective analysis of MRI scans was conducted in patients enrolled in the PURE-01 study (NCT02736266) from February 2017 to December 2019 who underwent pre- and postimmunotherapy mpMRI before radical cystectomy. Five readers independently reviewed the scans using VI-RADS and nacVI-RADS criteria. Diagnostic accuracy was evaluated for each reader, and the final histopathologic diagnosis served as the reference standard. Interreader agreement was assessed with the percentage of agreement, Conger κ, and Gwet agreement coefficient AC1. Results A total of 110 patients (median age, 67 years [IQR: 61-74]; 96 male) with 220 MRI scans were included; 80 (73%) patients had pure urothelial carcinoma. A total of 46 of 110 (42%) patients achieved a complete pathologic response. The sensitivity, specificity, and negative predictive value of nacVI-RADS 3 or higher for detecting residual disease (higher than stage ypT0) at radical cystectomy were 67%-84%, 63%-96%, and 63%-75%, respectively; for residual muscle-invasive disease (higher than stage ypT1), these values were 91%-98%, 55%-94%, and 93%-98%, respectively. The accuracy of nacVI-RADS was 72%-81% for stage ypT0 or higher disease and 71%-95% for stage ypT1 or higher disease. The accuracy of VI-RADS 3 or higher was 80%-95% for stage ypT1 or higher disease. The percentage of agreement for nacVI-RADS scores was 82% (κ = 0.62-0.65; AC1 = 0.65). Conclusion The nacVI-RADS scores showed good accuracy and reproducibility when assessing MIBC response to neoadjuvant immunotherapy. © RSNA, 2024 Supplemental material is available for this article.