Fig. 13
From: MRI of rectal cancer—relevant anatomy and staging key points
Circumferential margin of resection involvement. a A T3d tumour invades the mesorectal fascia on the left side (arrow). b A 1–2 mm fat plane between this mrT3b low rectal cancer and the sphincter complex (arrow) is observed and as such the circumferential margin of resection may be considered free