Vesical Imaging-Reporting and Data System (VI-RADS)
The Vesical Imaging–Reporting and Data System (VI-RADS) is a structured reporting scheme for multiparametric bladder MRI in the evaluation of suspected bladder cancer. A systematic approach to bladder lesion based on multiparametric MRI (mpMRI) was proposed by the European Association of Urology in 2018 .
Assessment categories
A combination of imaging findings - T2WI (SC-category), DWI (DW-category), and dynamic contrast enhancement (CE-category) - predicts the probability of cancer that is clinically significant, which is defined as the presence of any of the following.
Each lesion is assigned a score from 1 to 5 indicating the likelihood of clinically significant cancer:
VI-RADS 1
- muscle invasion is highly unlikely
- SC, CE and DW category 1
VI-RADS 2
- muscle invasion is unlikely to be present
- SC category 2-3
- CE and/or DW category 2
VI-RADS 3
- presence of muscle invasion is equivocal
- SC, CE and DW category 3
VI-RADS 4
- muscle invasion is likely
- SC category 3-5
- DW and/or CE category 4
VI-RADS 5
- invasion of muscle and beyond the bladder is very likely
- SC category 4-5
- DW and/or CE category 5
Radiographic features
Assessment for T2-WI with structural category (SC)
SC1-category
- uninterrupted low signal line representing the integrity of muscularis propria
- lesion <1 cm
- exophytic tumor with stalk and/or high signal thickened inner layer
SC2-category
- uninterrupted low signal line representing the integrity of muscularis propria
- lesion >1 cm
- exophytic tumor with stalk and/or high signal thickened inner layer or sessile/broad-based tumor with high signal thickened inner layer
SC3-category
- lack of category 2 findings with associated presence of an exophytic tumor without stalk
or - sessile/broad-based tumor without high signal thickened inner layer but with no clear disruption of low signal muscularis propria
SC4-category
interruption of low signal line suggesting extension of the intermediate signal tumor tissue to muscularis propria
SC5-category
extension of intermediate signal tumor to extravesical fat, representing the invasion of the entire bladder wall and extravesical tissues
Assessment for DCE with contrast-enhanced category (CE)
CE1-category
- no early enhancement of the muscularis propria
- lesions corresponding to SC1 findings
CE2-category
- no early enhancement of muscularis propria with early enhancement of inner layer
- lesions corresponding to SC2 findings
CE3-category
- lack of category 2 findings but with no clear disruption of low signal muscularis propria
- lesions corresponding to SC3 findings
CE4-category
tumor early enhancement extends focally to muscularis propria
CE5-category
tumor early enhancement extends to the entire bladder wall and to extravesical fat
Assessment for DWI/ADC with DW category (DW)
DW1-category
- muscularis propria with intermediate continuous signal on DWI
- lesion <1 cm
- hyperintense on DWI and hypointense on ADC, with or without stalk and/ or low signal thickened inner layer on DWI
DW2-category
- muscularis propria with continuous intermediate signal on DWI
- lesion >1 cm
- hyperintense on DWI and hypointense on ADC, with low signal stalk and/or low signal thickened inner layer on DWI
or - broad-based/sessile tumor with low/intermediate signal thickened inner layer on DWI
DW3-category
lack of category 2 findings (lesions corresponding to T2 category 3 findings) but with no clear disruption of low signal muscularis propria
DW4-category
high signal tumor on DWI and low signal tumor on ADC extending focally to muscularis propria
DW5-category
high signal tumor on DWI and low signal tumor on ADC extending to the entire bladder wall and extravesical fat