What is acute large bowel diverticulitis, and what are its CT and MRI features?
Acute diverticulitis involving the large bowel is inflammation/infection in the setting of large bowel diverticulosis (i.e., the presence of multiple outpouchings of the wall of the large bowel). This condition most commonly occurs in elderly adults, most commonly (95%) in the distal descending and sigmoid colon, and much less commonly (5%) in the ascending colon and cecum. Patients present with fever, abdominal pain (often in the left lower quadrant), and leukocytosis.
CT and MRI findings include pericolic inflammatory fat stranding, thickening and enhancement of an inflamed diverticulum, inflammatory segmental wall thickening of the large bowel, pericolic gas bubbles owing to bowel microperforation, and pericolic fluid. Potential complications include abdominal or pelvic abscess formation, mesenteric or portal vein thrombosis or gas, bowel obstruction, and fistula formation between the affected large bowel segment and the bladder, vagina, small bowel, other portion of large bowel, or skin