## 5 Diagnostic Performance of VI-RADS  
Since its introduction in 2018 [6], the VI-RADS reporting scheme for mpMRI has shown excellent results in differentiating MIBC from NMIBC. The most important factors in determining the diagnostic performance of VI-RADS were accuracy--measured as area under the curve (AUC) of hierarchical summary receiver operating characteristic (HSROC) curve--sensitivity, specificity, and inter-reader agreement. Even though the vast majority of published studies are single-institution and retrospective in nature, consistent data has recently been gained from prospective multicentre studies and systematic reviews. Five different meta-analyses on VI-RADS unanimously reported high sensitivity and specificity for predicting muscle invasion as well as a high diagnostic accuracy [13; 14; 15; 16; 17]. As summarised in Table 5, sensitivity, specificity and AUC ranged between 0.83-0.92, 0.82-0.90 and 0.93-0.94, respectively, when a cut-off score of VI-RADS \(\geq\) 3 was used, and 0.77-0.78, 0.94-0.97 and 0.91-0.94, respectively, when a cut-off score of VI-RADS \(\geq\) 4 was used. \begin{table}
\begin{tabular}{c c c} \hline
**VI-RADS** & **DWI/CE Categories** & **Structural Category (SC)** \\ \hline VI-RADS 1 & & DWI and CE 1 & SC 1 \\ (muscle invasion highly unlikely) & & \\ \hline VI-RADS 2 & & & \\ (muscle invasion unlikely) & & & \\ \hline VI-RADS 3 & & & \\ (muscle invasion equivocal) & & & \\ \hline VI-RADS 4 & & & \\ (muscle invasion likely) & & & \\ \hline VI-RADS 5 & & & \\ (muscle invasion highly likely) & & & \\ \end{tabular}
\end{table} 
Table 4: VI-RADS scoring system. \begin{table}
\begin{tabular}{c c} \hline
**Contrast-Enhanced (CE) Category** & **Bladder Cancer (BC) Lesion** \\ \hline CE category 1 & No early enhancement of the muscularis propria. \\ \hline CE category 2 & No early enhancement of the muscularis propria, \\  & but early enhancement of the inner layer. \\ \hline  & Absence of category 2 findings, without any \\ CE category 3 & evidence of clear disruption of hypo-intensity of \\  & muscularis propria. \\ \hline CE category 4 & Focal extent of tumour early enhancement in the \\  & muscularis propria. \\ \hline CE category 5 & Extent of the tumour early enhancement in the \\  & entire bladder wall and extravesical fat. \\ \hline \end{tabular}
\end{table} 
Table 3: Contrast-enhanced (CE) categories and corresponding lesions. \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Author**} & \multirow{2}{*}{**\# Studies**} & \multirow{2}{*}{**\# Participants**} & \multicolumn{6}{c}{**Control V-RADS 3**} & \multicolumn{6}{c}{**Control V-RADS 4**} \\ \cline{3-11}  & & & & **Sensitivity (\%)** & **Specificity (\%)** & **Specificity (\%)** & **License-Observer** & **Accuracy (AUC)** & **Sensitivity (\%)** & **Specificity (\%)**  
[PERSON] et al. [19] and [PERSON] et al. [18] performed two meta-analyses to determine the inter-reader reliability, reporting their pooled Cohen's kappa (\(k\)) coefficient. These were found to be high to very high, ranging from 0.76 to 0.83 (Table 5). Similarly, a more recent prospective multi-centre study [20] showed that reporting bladder MRI according to the VI-RADS score provided a substantial inter-reader agreement (\(k\) = 0.81) among radiologists of different levels of expertise, with overall VI-RADS showing the highest AUC (0.95) compared to individual bladder MRI sequences (T2 WI: 0.94; DWI: 0.93; DCE: 0.94). [PERSON] et al. in a retrospective cohort of 66 patients obtained high to very-high interobserver agreement and accuracy for local staging, with a high diagnostic performance of the overall VI-RADS score for radiologists and also urologists [21]. Furthermore, VI-RADS was highly accurate for the diagnosis of different variants of MIBC, other than pure urothelial carcinoma [22]. An important point raised by [PERSON] et al.