Cross-Sectional Imaging of the Large Bowel

Abstract

There has been considerable evolution of imaging techniques applied to visualization of pathology related to the large bowel. As recently as 10–15 yr ago, the predominant technique for colon imaging depended on plain film radiography. More recently, technological developments have facilitated use of computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound. Plain radiography is now considered to be of limited relative value, and generally, a test having low diagnostic yield. Radiography in combination with rectally administered contrast agents has been found useful for assessing mucosal and structural abnormalities. Optimal technique uses double-contrast barium enema, where a combination of a positive contrast, barium, thinly coats the intestinal mucosal surface, while the lumen is distended with a negative contrast, air, which is insufflated transrectally. In order to achieve effective coating of the entire colon, the patient is required to perform a variety of maneuvers while on the imaging table. There is exhaustive review of plain film and double-contrast radiography techniques in the literature, and this chapter will instead concentrate on newer state-of-the-art imaging based on CT and MR.