MRI of the rectum: non-neoplastic disease.

The rectum has become the most successful area of the gastrointestinal tract to be studied with MRI. Its anatomical location, fixed in the pelvic fat, and its lack of peristalsis, make it an ideal organ to be scanned with MRI. In addition, MRI allows a direct sagittal and coronal display, of key importance to colorectal surgeons whose terminology and approach are based on the coronal plane. The sagittal plane allows the depiction of the relation of the rectum to the sacrum, uterus and prostate, with detail not available by other imaging techniques, and the use of endorectal coils allows excellent demonstration of the rectal wall. Although MRI has been used primarily to study rectal carcinoma, other diseases, congenital, inflammatory and vascular in origin, can be studied using the correct technique.