Muscle invasion decides cystectomy versus resection: multiparametric MRI scores the likelihood with VI-RADS on T2, DWI and dynamic contrast; CT stages nodes and metastases.
Orient first
- VI-RADS scores 1–5 on multiparametric MRI from the relation of the tumour to the muscularis propria (verify the current VI-RADS document).
- An intact low-signal inner layer (stalk) under the tumour favours non-muscle-invasive disease.
- MRI is best before transurethral resection — post-resection oedema overcalls invasion.
Acquire the study
- T2 in three planes orthogonal to the tumour base; DWI b 0/800–1000 with ADC; dynamic post-contrast T1.
The manoeuvre
- T2: tumour size in mm, stalk, and whether the dark muscularis layer is intact under the base.
- DWI: the tumour restricts; an intact low-signal inner layer between tumour and muscle favours VI-RADS 1–2.
- Dynamic contrast: early enhancement of the submucosa (inner layer) vs disruption into muscle.
- Assign VI-RADS 1–5; perivesical fat invasion; ureteric orifice involvement.
What confirms it
- A bladder tumour with a VI-RADS score and staging; histology after resection confirms.
What licenses you to exclude it
- VI-RADS 1–2 makes muscle invasion unlikely; it does not replace histology.
The classic misread
- Scoring a recently resected tumour — oedema and granulation tissue mimic invasion.