Diagnosis of muscle-invasive urothelial carcinoma with variant histology using biparametric MRI and VI-RADS in a radical cystectomy cohort

Motivation: To determine if contrast-free biparametric MRI (bpMRI), which offers potential cost, comfort and safety advantages, could replace multiparametric MRI (mpMRI) in diagnosing muscle-invasive bladder cancer (MIBC) in patients with urothelial carcinoma of variant histology (VUC). Goal(s): To compare the diagnostic accuracy of bpMRI and conventional mpMRI for detecting MIBC in patients with VUC who underwent radical cystectomy (the optimal reference standard). Approach: A retrospective, multicenter diagnostic study using radical cystectomy as the reference standard. Results: The diagnostic performance of bpMRI was confirmed to be weaker than that of mpMRI in the assessment of muscle invasion in bladder VUC. Impact: When applying VI-RADS, bpMRI had weaker diagnostic performance than mpMRI in assessing muscle invasion in patients with bladder VUC who had radical cystectomy (the optimal reference standard). Consequently, we recommend employing mpMRI-based methods for evaluating muscle invasion in bladder VUC.