Beyond VI-RADS: incremental value of quantitative mpMRI measurements for identifying muscle-invasive bladder cancer

To assess whether simple quantitative multiparametric magnetic resonance imaging (mpMRI) measurements add diagnostic value to Vesical Imaging-Reporting and Data System (VI-RADS) scores for preoperative identification of muscle-invasive bladder cancer (MIBC).

Tumor diameter, tumor-wall contact length, and VI-RADS scores were evaluated. The primary outcome was pathological MIBC. Diagnostic performance was assessed using receiver operating characteristic analysis, logistic regression, bootstrap internal validation, reclassification indices, calibration, and decision curve analysis.

The combined model including VI-RADS score (overall), average tumor diameter, and average tumor-wall contact length achieved an AUC of 0.808 (95% CI 0.739-0.876), compared with 0.769 (95% CI 0.702-0.836) for VI-RADS alone (DeLong P = 0.023). Continuous net reclassification improvement was 0.370 (95% CI 0.046-0.734), and integrated discrimination improvement was 0.034 (95% CI 0.003-0.116). Decision curve analysis suggested a modest gain in net benefit across threshold probabilities of 0.20-0.80.

Quantitative mpMRI measurements provided a modest, statistically significant but clinically limited incremental value beyond VI-RADS for identifying MIBC, although VI-RADS remained the main predictor.