Water Enema Multidetector CT Colonography: Technique, Role and Imaging Findings in Ulcerative Colitis

Abstract

Water enema multidetector CT (WE-MDCT) is a reproducible, safe, and well-tolerated technique that combines preliminary bowel cleansing, retrograde colonic distension by intraluminal water, and pharmacological hypotonisation, with a contrast-enhanced MDCT acquisition of the abdomen and pelvis. Increasingly proposed as the best imaging technique in patients with suspected or proven colorectal tumors, WE-MDCT provides the most accurate, high-resolution multiplanar visualization of the colonic wall thickness and enhancement patterns in normal and pathologic conditions, with optimal contrast between the wall itself, the hypodense lumen, and the pericolonic fat. Therefore, although with the drawback of the radiation dose, WE-MDCT represents an appealing modality to investigate also chronic inflammatory disorders of the large bowel. The WE-MDCT technique and acquisition protocol are discussed, including patient preparation and study interpretation. Elective WE-MDCT may be indicated as a complementary technique in patients with impossible, incomplete, or inconclusive endoscopy, to study a stricture’s features and the upstream bowel. In patients with ulcerative, indeterminate, or Crohn’s colitis, WE-MDCT may be helpful to assess the disease’s longitudinal distribution, mural thickening and enhancement related to inflammatory activity, and the presence of endoluminal pseudopolyps. Furthermore, WE-MDCT comprehensively shows associated perivisceral changes, complications involving the adjacent organs, extraintestinal manifestations, and features that may suggest the possibility of an underlying colorectal carcinoma.