A proposed inclusion of magnetic resonance imaging features to the VI RADS to enhance its accuracy in predicting muscle invasion

Abstract

BackgroundMuscle invasion in bladder cancer is a paramount factor in prognosis and setting the management plan. MRI is gaining preference in this field, being noninvasive with no radiation hazards and having good resolution, especially with the development of the standardized system of (VI RADS). Moreover, multiple other imaging features can aid in predicting muscle invasion. We studied some of the most commonly reported features to develop the most reliable combination to anticipate the presence of muscle invasion.ResultsOur prospective study on 80 patients showed 39 (48.75%) muscle invasive (MIBC) and 41 (51.25%) non-muscle invasive (NMIBC) bladder cancer cases. The inter-observer agreement on the VI RADS score and the ADC measurements were very good and they had high-accuracy predicting muscle invasion with areas under the curve (AUCs) on ROC curve analysis reaching 0.905 and 0.857, respectively. The imaging variables that showed statistically significant differences between NMIBC and MIBC cases were: the multiplicity of the lesions, vesicoureteric junction (VUJ) involvement with distal ureteric backpressure, tumor–wall contact length (TCL), tumor volume, tumor shape (sessile or papillary), presence of a stalk, the final VI RADS score and the ADC value. On the multiple regression analysis model, the multiplicity of the lesions, the minimum ADC value by ROI method and the final VI RADS score showed independent correlation with muscle invasion, negatively with the first two and positively with the latter. The combination of the six statistically significant variables on the univariate regression analysis (final VI RADS score, minimum ADC by ROI, multiplicity, index tumor shape, TCL and distal ureteric backpressure changes) showed the best AUC (0.944).ConclusionsVI RADS has good diagnostic accuracy regarding muscle invasion; however, this can even be enhanced by including other quantitative and qualitative commonly reported MRI features as a proposed modification to the VI RADS.