Fig. 6
From: MRI of rectal cancer—relevant anatomy and staging key points
The peritoneal reflection, when visible, may present with a seagull or V-shaped appearance on the (oblique) axial plane (arrow in a). The sagittal plane is depicted as a hypointense line extending from the rectal wall to the roof of the mesorectal fascia (arrow in b). It is more easily identified whenever there is a small amount of peritoneal effusion, which will accumulate immediately above it (arrow in c)