What is the role of imaging studies in the diagnosis of ulcerative colitis (UC)?

Updated: Feb 23, 2019
  • Author: Ali Nawaz Khan, MBBS, FRCS, FRCP, FRCR; Chief Editor: Eugene C Lin, MD  more...
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Answer

Traditionally, barium enema examination has been the mainstay of radiologic investigation for suspected ulcerative colitis. Plain abdominal radiographs (see the images below) are a useful adjunct to imaging in cases of ulcerative colitis of acute onset. In severe cases, the images may show colonic dilatation, suggesting toxic megacolon, perforation, obstruction, or ileus. Radiographic imaging has an important role in the workup of patients with suspected IBD and in the differentiation of ulcerative colitis and Crohn disease. Because of its ability to depict fine mucosal detail, double-contrast barium enema examination is a valuable technique for diagnosing ulcerative colitis and Crohn disease, even in patients with early disease. [5, 6, 7]

Double-contrast barium enema studies in a 44-year- Double-contrast barium enema studies in a 44-year-old man known to have a long history of ulcerative colitis. Images show total colitis and extensive pseudopolyposis.
Plain abdominal radiograph in a patient (same as i Plain abdominal radiograph in a patient (same as in the previous image) who presented with an acute exacerbation of his symptoms. Image shows thumbprinting in the region of the splenic flexure of the colon.
Plain abdominal radiograph obtained 2 days later i Plain abdominal radiograph obtained 2 days later in the same patient as in the previous image shows distention of the transverse colon associated with mucosal edema. The maximum transverse diameter of the transverse colon is 7.5 cm. The patient was treated for toxic megacolon.

Transabdominal ultrasonography (US) is a noninvasive modality that may be helpful in the diagnosis of IBD, but it cannot be used to distinguish between ulcerative colitis and Crohn disease. US is also a useful technique in the investigation of biliary complications of the disease. [8]

Capsule endoscopy is sensitive for early mucosal inflammation, but it can only detect mucosal changes, whereas magnetic resonance imaging (MRI) and intestinal ultrasonography are able to reveal transmural inflammation as well as identify complications

Generally, CT has a limited role in the diagnosis of uncomplicated ulcerative colitis. However, CT plays an important role in the differential diagnosis of ulcerative colitis, and it is an excellent modality in the diagnosis of complications associated with the disease. Biliary dilatation suggests primary sclerosing cholangitis.

Computed tomography enterography (CTE), with its high contrast resolution and rapid imaging capability, allows evaluation of intramural and extra-intestinal involvement of UC and complications such as fistula, abdominal abscess, or cellulitis. CTE is now widely used to diagnose and monitor inflammatory bowel disease (IBD), including UC. [9]

Cross-sectional imaging studies such as CT, MRI, and US are useful for showing the effects of these conditions on the wall of the bowel and for demonstrating intra-abdominal abscesses and other extraluminal findings in patients with more advanced disease. Thus, barium studies and cross-sectional imaging studies have complementary roles in the evaluation of ulcerative colitis. [10, 8]

Radionuclide studies (see the image below) are useful in cases of acute fulminant colitis when colonoscopy or barium enema examination is contraindicated. Radionuclide studies are also useful in depicting disease activity and the extent of disease and in monitoring the response to therapy. [11]

Radiologic findings in cases of acute infective enterocolitis from infection caused by Entamoeba histolytica (amebiasis), cytomegaloviral colitis, and Isospora, Salmonella, Shigella, or Yersinia may be similar to the findings seen in cases of ulcerative colitis; this is especially true with CT scans.

Scan obtained with technetium-99m hexamethylpropyl Scan obtained with technetium-99m hexamethylpropylamine oxime (HMPAO)–labeled WBCs in a patient with active colitis involving the transverse and descending colon.

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