What is the role of CT scanning in the workup of ulcerative colitis (UC)?

Updated: Apr 23, 2019
  • Author: Ali Nawaz Khan, MBBS, FRCS, FRCP, FRCR; Chief Editor: Eugene C Lin, MD  more...
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Cross-sectional imaging plays a prominent role in the assessment of IBD of the colon. The clinical history, laboratory data, and extent of involvement are used in conjunction with the radiographic results to reach a specific diagnosis.

CT is preferred to MRI for assessing the extent of inflammatory disease in and beyond the bowel wall. An added benefit of CT over MRI is the fact that patients with abscesses or large fluid collections may undergo drainage while in the CT scanner. CT and MRI may help to distinguish between cases of ulcerative colitis with minimal wall thickening and cases of Crohn disease with marked wall thickening with concomitant skip lesions and fistula and/or abscess formation. [22]

Although many CT findings in ulcerative colitis are striking, they are not considered specific. Some features do suggest a diagnosis of IBD, and specific features may indicate a single diagnosis of ulcerative colitis with a high degree of confidence. The halo sign typically occurs in ulcerative colitis.

The utility of multidetector-row computed tomography (MDCT) in assessing the severity of ulcerative colitis (UC) in comparison with clinical assessment, colonoscopy, and histopathology has been studied. Disease severity assessment by MDCT demonstrates positive correlation with severity established by clinical assessment and colonoscopy. Only increasing wall thickness, as graded on MDCT, correlates with histopathologic disease severity. [23]

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