VI-RADS score and tumor contact length in MRI: A potential method for the detection of muscle invasion in bladder cancer

Abstract

Background

Vesical Imaging Reporting and Data System (VI-RADS) is a useful tool for evaluating muscle layer invasion of bladder cancer (BCa) on magnetic resonance imaging (MRI).

Purpose

To evaluate the diagnostic performance of bladder MRI to detect the muscle layer invasion of BCa using VI-RADS score and quantitative MRI parameters.

Methods

Preoperative bladder MRI was performed in 73 BCa patients. Two observers independently evaluated the MR blinded to histopathological data and classified the tumors according to VI-RADS criteria. Moreover, the quantitative parameters (maximum tumor diameter; Dmax, tumor contact length; TCL, and tumor apparent diffusion coefficient; ADC values) were independently measured by observers. The diagnostic performance of the VI-RADS score and quantitative values were evaluated by using receiver operating characteristic (ROC) analysis. Interobserver agreement was evaluated using the weighted-kappa coefficient (κ).

Results

For the VI-RADS score, the AUC (area under the curve) was 0.968 and accuracy was 90.4% for Observer 1, and AUC was 0.953, accuracy was 89% for Observer 2. The AUC of TCL, TCL/DMax, and ADC values was 0.918, 0.675, and 0.832. In patients with a VI-RADS score ≥ 3, when a threshold value of TCL > 19.5 mm is used as complementary to the VI-RADS score, the accuracy of MRI for Observer-1 increases 100% and 97.26% for Observer-2. There was a good-excellent agreement between the observers in assessing the VI-RADS scores and quantitative parameters.

Conclusion

Evaluation of bladder MRI using both VI-RADS criteria and TCL is successful and highly reproducible for detecting muscle layer invasion in patients with BCa.