Table 2 MRI protocol and diagnostic elements for rectal cancer that radiologists should consider in their clinical activity and report
MR Protocol | MRI Staging | MRI Restaging |
|---|---|---|
✓ T2-weighted axial perpendicular to the main tumour axis (slice thickness ≤3 mm) ✓ DWI with the same T2-weighted inclination ✓ high b value (≥800 mm2/s) ✓ endorectal filling and anti-peristaltic drugs in selected cases | ✓ site (low, middle, high rectum) of the tumour (circumferential location) ✓ longitudinal extension of the tumour ✓ distance of the caudal tumour margin from anorectal junction ✓ mesorectal involvement and tumour free resection margin ✓ extramural vascular invasion (EMVI) ✓ nodal involvement (size, shape, MR signal and borders) | ✓ same criteria used for the MR staging regarding T ✓ specified criteria concerning nodal restaging ✓ potential pitfalls on DWI (misinterpretation of low signal on ADC map from fibrosis, susceptibility effects, T2 shine-through of fluid in rectal lumen, suboptimal sequence angulation and collapsed rectal wall) |