Imaging like MRI and CT scans can help doctors detect signs of Crohn’s disease, like bowel wall thickening or ulcers. Ultrasounds and X-rays may also be of use.

Crohn’s disease is a chronic bowel disease that causes inflammation along your digestive tract. Experts collectively classify it as an inflammatory bowel disease (IBD) with ulcerative colitis.

The gold standard technique for diagnosing Crohn’s disease is endoscopy (using a tiny camera to examine the bowels) with biopsy (analyzing a small tissue sample). But doctors use other tests, including:

  • a physical exam
  • lab tests
  • imaging

Imaging tests play an essential role in:

  • ruling out other conditions
  • assessing the extent of your disease
  • monitoring you for complications

This article explains why and when doctors use these imaging techniques and what signs they look for that may indicate Crohn’s disease.

An MRI is the gold standard imaging technique for viewing patches of inflammation that indicate Crohn’s disease. They can also help a doctor notice complications and the extent of your disease activity.

Features of Crohn’s disease that may show up on an MRI include:

Crohn’s disease often requires repeated scans of your intestines to track how your disease changes over time. Unlike CT scans and X-rays, an MRI doesn’t expose your body to radiation.

The MRI techniques doctors use to visualize Crohn’s include:

  • MR enteroclysis: During this procedure, you receive a tube through your nose that leads to your small intestines. A healthcare professional then injects a contrast solution through this tube.
  • MR enterography: During this procedure, you drink a fluid that fills your bowel. This can help your doctor monitor disease activity and the effectiveness of treatments such as immune-modulating agents.

In a 2018 study, researchers compared the accuracy of MR enterography and ultrasound for identifying Crohn’s gut changes to a panel of tests used as the reference standard. The researchers found that MR enterography was better than ultrasound in:

  • diagnosing small bowel disease extent (80% versus 70%)
  • detecting disease presence (97% versus 92%)
  • correctly ruling out small bowel disease extent (95% versus 81%)
  • correctly ruling out disease presence (96% versus 84%)
MRI showing signs of Crohn's diseaseShare on Pinterest
An MRI can show thickened bowel walls, creeping fat, and skip lesions common in Crohn’s disease.
Bhargava R, Hahn G, Hirsch W, Kim MJ, Mentzel HJ, Olsen OE, Stokland E, Triulzi F, Vazquez E. Libertas Academica Ltd. CC-BY-NC 3.0

A CT scan uses a series of X-rays to create a detailed image of your abdomen. Doctors use them to assess Crohn’s disease:

  • activity
  • extent
  • complications

Features of Crohn’s disease that show up on a CT scan include:

  • thickened bowel walls
  • creeping fat
  • comb sign” showing the swelling of blood vessels in one of the bowel layers

A doctor may recommend a conventional CT scan with or without a contrast dye injection if you have a sudden onset of Crohn’s disease with no prior diagnosis. They may also recommend a conventional CT scan to check for complications of Crohn’s, such as:

CT enterography is a type of CT scan that can better visualize your small intestines than a conventional scan. This procedure involves drinking a special contrast liquid that shows up in the scanner. CT scans can accurately identify or rule out Crohn’s disease in more than 90% of cases.

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A CT scan of Crohn’s disease can show inflammation. You may also see the “comb sign” showing enlarged vessels in the mesenteric layer.
Copyright © 2013 Korean Society of Gastrointestinal Endoscopy CC BY-NC 3.0

Ultrasound is a radiation-free type of imaging that uses sound waves to produce an image of your gastrointestinal tract. It can also help identify health complications of other organs, such as your:

  • liver
  • bladder
  • gallbladder

Abdominal ultrasounds are quick and widely available. They may help doctors identify:

  • whether your disease is in remission
  • potential complications
  • disease severity

Ultrasounds can correctly identify Crohn’s inflammation around 93% of the time. They’re better at visualizing certain areas, such as the area between your large and small intestines and the lower part of your large intestines.

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An ultrasound can help doctors detect bowel wall thickening in Crohn’s disease. It can also detect complications, like abscesses or fistulas.
Copyright © 2016 Rune Wilkens et al. CC BY 4.0

X-rays have a limited function in the diagnosis of Crohn’s disease. However, they can help identify complications such as:

  • ulcers
  • blockages
  • fistulae

A barium enema involves putting a contrast dye into your anus with a tube so your doctors can better visualize your bowel on an X-ray.

Doctors don’t frequently use barium enemas. They more often perform CT scans or colonoscopies to identify changes to your colon.

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A barium enema can show irregularities in the colon wall, such as swelling and ulcers.
Mediscan / Alamy Stock Photo

Imaging can help your doctor understand the extent of your Crohn’s disease and screen you for complications. Many experts consider an MRI the most accurate imaging tool for assessing Crohn’s, but CT scans and ultrasounds can make quicker and cheaper alternatives.

Usageassessing disease activity, extent, and complicationsassessing disease activity, extent, and complicationsassessing disease activity, severity, and complications assessing complications
Priceexpensivemoderately expensivecheapcheap
Accuracyhigher accuracy for detecting disease activity than ultrasoundcomparable to MRIless accurate than MRI but still highly accuratelimited use
Radiation exposurenoyesnoyes