What is the role of imaging studies in the diagnosis of Crohn disease?

Updated: Jul 26, 2019
  • Author: Leyla J Ghazi, MD; Chief Editor: Praveen K Roy, MD, AGAF  more...
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Various imaging modalities are available to aid in the diagnosis and management of Crohn disease. Contrast radiologic studies are recommended to determine disease extent, disease severity and complications, and treatment strategy. [12] The choice of modality depends on the clinical question being asked, as follows:

  • Colonoscopy is the technique of choice to assess disease activity in patients with symptomatic colonic Crohn disease or ulcerative colitis; [59]  complementary cross-sectional imaging can be used to assess phenotype and as an alternative to evaluate disease activity [59]

  • Upper gastrointestinal (GI) endoscopy and/or colonoscopy and histologic examination are recommended in cases of suspected Crohn disease on the basis of clinical findings; [12] upper GI endoscopy is also recommended when lower GI endoscopy is unable to definitely diagnose Crohn disease or in the presence of upper GI symptoms, but not for asymptomatic newly diagnosed patients [59, 12]

  • Plain radiography or computed tomography (CT) scanning of the abdomen can be used to assess for bowel obstruction; these studies can also be used to assess the pelvis for the presence of any intra-abdominal abscesses

  • The use of CT enterography or magnetic resonance (MR) enterography is replacing small bowel follow-through (SBFT) studies; the enterographic images can better distinguish between inflammation and fibrosis

  • Magnetic resonance imaging (MRI) of the pelvis or endoscopic ultrasonography (ie, transrectal ultrasonography) can identify perianal fistulae anatomy and activity and detect the presence or absence of pelvic and perianal abscesses

Capsule endoscopy is sensitive for early mucosal inflammation, but it can only detect mucosal changes, whereas MRI and intestinal ultrasonography are able to reveal transmural inflammation, as well as identify complications. [59, 12] Furthermore, MRI detects fistulae, deep ulcerations, and a thickened bowel wall. [59] Ultrasonography is inexpensive and can be performed at the point of care by the treating gastroenterologist.

Ultrasonography, CT scanning, and MRI can determine pretreatment and posttreatment disease activity or identify disease complications. [12] Cross-sectional imaging should be used to detect strictures in the case of complications. [59] Because of radiation associated with CT scanning, the preferred methods are MRI and intestinal ultrasonography. Cross-sectional imaging is also recommended for the detection of abscesses. For the diagnosis of perianal Crohn disease, clinical and endoscopic rectal examination, as well as MRI, is recommended; ultrasonography in the absence of anal stenosis or transperineal ultrasonography is an alternative to MRI. [59]

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