A novel pathway to detect muscle-invasive bladder cancer based on integrated clinical features and VI-RADS score on MRI: results of a prospective multicenter study

Abstract

Purpose: To determine the clinical, pathological, and radiological features, including the Vesical Imaging-Reporting and Data System (VI-RADS) score, independently correlating with muscle-invasive bladder cancer (BCa), in a multicentric national setting.

Method and materials: Patients with BCa suspicion were offered magnetic resonance imaging (MRI) before trans-urethral resection of bladder tumor (TURBT). According to VI-RADS, a cutoff of ≥ 3 or ≥ 4 was assumed to define muscle-invasive bladder cancer (MIBC). Trans-urethral resection of the tumor (TURBT) and/or cystectomy reports were compared with preoperative VI-RADS scores to assess accuracy of MRI for discriminating between non-muscle-invasive versus MIBC. Performance was assessed by ROC curve analysis. Two univariable and multivariable logistic regression models were implemented including clinical, pathological, radiological data, and VI-RADS categories to determine the variables with an independent effect on MIBC.

Results: A final cohort of 139 patients was enrolled (median age 70 [IQR: 64, 76.5]). MRI showed sensitivity, specificity, PPV, NPV, and accuracy for MIBC diagnosis ranging from 83-93%, 80-92%, 67-81%, 93-96%, and 84-89% for the more experienced readers. The area under the curve (AUC) was 0.95 (0.91-0.99). In the multivariable logistic regression model, the VI-RADS score, using both a cutoff of 3 and 4 (P < .0001), hematuria (P = .007), tumor size (P = .013), and concomitant hydronephrosis (P = .027) were the variables correlating with a bladder cancer staged as ≥ T2. The inter-reader agreement was substantial (k = 0.814).

Conclusions: VI-RADS assessment scoring proved to be an independent predictor of muscle-invasiveness, which might implicate a shift toward a more aggressive selection approach of patients' at high risk of MIBC, according to a novel proposed predictive pathway.

Keywords: Hematuria; Magnetic resonance imaging; Muscle-invasive bladder cancer; Pathway; VI-RADS.

Fig. 1

ROC analysis for the performance of more and less experienced readers in detecting muscle-invasive bladder cancer. ROC, receiver operating curve; VI-RADS, Vesical Imaging-Reporting and Data System

Fig. 2

Case example of a 66-years-old female that was incorrectly scored as a VI-RADS 4 by the less experienced readers, but correctly scored as VI-RADS 2 by the more experienced readers. (a–b–c) Axial, sagittal and coronal T2-weighted imaging showing a pedunculated bladder tumor (20 mm) at the right lateral wall; (d–e) diffusion-weighted imaging and ADC map showing the “inchworm sign”, typical of non-muscle-invasive bladder cancer; (f) dynamic contrast-enhanced MRI showing integrity of the muscularis propria layer and enhancement of the “inner layer” (arrow). The lesion should be classified as VI-RADS 2. VI-RADS, Vesical Imaging-Reporting and Data System; ADC, apparent diffusion coefficient

Fig. 3

Proposed predictive pathway based on the clinical and radiological variable showing independent correlation to MIBC. US, ultrasound; CT, computerized tomography; VI-RADS, Vesical Imaging-Reporting and Data System; TURBT, trans-urethral resection of bladder tumor; BCG, bacillus Calmette-Guérin; TUR, trans-urethral resection; RC, radical cystectomy; NAC, neoadjuvant chemotherapy