Fig. 11
From: MRI of rectal cancer—relevant anatomy and staging key points
T stages and substages. T1is: tumour in situ; T1sm1/2: tumour invades the submucosa, but not its full thickness; T1sm3: tumour invades the full thickness of the submucosa; T2 early: tumour focally invades the muscularis propria; T2 advanced: tumour invades the full thickness of the muscularis propria; T3a: tumour extends < 1 mm into the mesorectal fat; T3b: tumour extends between 1 and 5 mm into the mesorectal fat; T3c: tumour extends between 5 and 15 mm into the mesorectal fat; T3d: tumour extends > 15 mm into the mesorectal fat; T4a: tumour invades the peritoneum; T4b: tumour invades adjacent organs