Table 1. .

MRI VI-RADS classification according to T₂WI, DWI and DCE-MRI

VI-RADS category	MRI sequence
	T2WI (SC)	DWI	DCE-MRI
1	Non-muscle invasion in term of uninterrupted low SI line. Lesion less than 1 cm.	Intermediate SI of muscle layer on DWI. Lesion < 1 cm, hyper intense on DWI and hypointense on ADC, with or without stalk and/or low SI thickened inner layer on DWI.	No muscle invasion in term of no early enhancement of the muscle layer (lesions corresponding to SC1 findings)
2	The same as (C1), but with lesion more than 1 cm.	The same as (C1), but with: -  Lesion > 1 cm.  Having low SI stalk and/or low SI thickened inner layer on DWI, with low/intermediate SI thickened inner layer on DWI).	The same as (C1), but with early enhancement of inner layer (lesions corresponding to SC2 findings).
3	Lack of (C2) findings, but no clear disruption of low signal muscle layer as in exophytic tumor without stalk or sessile tumor without high signal inner layer.	Lack of (C2) findings (lesions corresponding to SC3 findings) but with no clear disruption of low SI muscle layer.	Lack of (C2) findings (lesions corresponding to SC3 findings) but no definite clear muscle invasion.
4	Muscle invasion in term of interruption of low signal muscle layer.	High SI tumor on DWI and low SI tumor on ADC extending focally to muscle layer.	Muscle invasion with focal early enhancement of muscle layer.
5	Extension to extra vesical fat and surroundings.	High SI tumor on DWI and low SI tumor on ADC extending to the entire bladder wall and extra vesical fat.	Early enhancement extends to bladder wall with extension to extra vesical fat.

ADC, apparent diffusion coefficient; DCE, dynamic contrast enhanced; DWI, diffusion-weighted imaging; SC, structural category; SI, signal intensity; T₂WI, T₂ weighted imaging.