Exploratory Study of Quantitative MRI Parameters Providing the Novel Value in Discriminating Muscle-Invasive Bladder Cancer [Presidential Award Proceedings]

Accurate discrimination between muscle and non-muscle-invasive bladder cancer (MIBC and NMIBC, respectively) is essential for treatment planning and prognosis prediction. The present study investigated whether quantitative magnetic resonance imaging (MRI) parameters, including synthetic MRI (SyMRI), can enhance the diagnostic value of the Vesical Imaging Reporting and Data System (VI-RADS). Sixty-four patients (54 males, median age 73 years) with pathology confirmed MIBC or NMIBC were included. Bladder MRI, using VI-RADS scores and SyMRI, was performed before transurethral resection. Pretherapeutic quantitative parameters, including T1, T2, proton density from SyMRI, and apparent diffusion coefficient (ADC) values, were measured. Statistical analysis included the Cochran-Armitage trend and Wilcoxon rank-sum tests, and logistic regression models with receiver operating characteristic (ROC) analysis. VI-RADS scores were associated with the incidence of MIBC ( p<0.0001). Patients with MIBC exhibited significantly lower T1, T2, and ADC values (1451 ms, 106 ms, 0.88×10−3 mm2/s, respectively) than those with NMIBC (1644 ms, 124 ms, 1.46×10−3 mm2/s) (p<0.05 for all). ADC values had the highest area under the ROC curve (AUC, 0.93；cut-off, 1.22×10−3 mm2/s；sensitivity, 100％；specificity, 78％). Combining ADC values with VI-RADS scores improved MIBC prediction (AUC 0.98), although not significantly ( p＝0.084). For VI-RADS scores 2 and 3 (n＝44), a low ADC value (cut-off 1.22×10−3 mm2/s) prevented underdiagnosis of MIBC with high sensitivity (n＝6/6 [100％]). ADC analysis and VI-RADS were effective in distinguishing MIBC from NMIBC. Combining ADC values with VI-RADS scores demonstrated potential as an imaging marker for evaluation of MIBC.