Computed tomography and magnetic resonance imaging of the acute abdomen.

CT is a noninvasive investigation that in many instances is more sensitive in elucidating intra-abdominal and retroperitoneal disease than is conventional radiography. With modern scanners, the procedure is rapid and efficient and suitable for the most severely ill and infirm. The scans are easily interpretable, and the anatomic and morphologic depiction of disease is readily understood by those with surgical training. Information regarding the state of the bowel wall, mesentery, and intraperitoneal and retroperitoneal structures is displayed in greater detail than by any other diagnostic imaging modality. The use of intravenous contrast medium is rarely essential. The concentration of iodinated contrast needed for opacification of the bowel is no greater than 2 per cent to 5 per cent and will not complicate bowel surgery, as would standard upper gastrointestinal or barium enema studies. Abscess, free air, calcium, and intraperitoneal fluid are very sensitively detected. CT is extremely useful in aiding surgical decision making in the acute abdomen and is complementary to or has replaced conventional studies.