CT enterography (CTE) is a non-invasive technique for diagnosing small bowel disorders.

Indications

Indications for CT enterography include ^4,8:

• Crohn disease

  • ​diagnosis and complications (primarily)

  • most common indication

• suspected small bowel bleeding, usually performed after a negative endoscopy

• suspected small bowel tumor, e.g. neuroendocrine tumor (NET), polyposis syndromes

• celiac disease: assess for complications such as lymphoma

• partial small bowel obstructions, e.g. postoperative adhesions, radiation enteritis, scleroderma

• chronic diarrhea and/or abdominal pain

• suspected chronic mesenteric ischemia

Advantages ​

• useful in the assessment of the solid organs and provides a global overview of the abdomen ¹

Disadvantages 

• exposure to ionizing radiation

Technique

NB: This article is intended to outline some general principles of protocol design. The specifics will vary depending on CT hardware and software, radiologist's and referrer's preferences, institutional protocols, and patient factors (e.g. allergy and fluid intake restrictions). 

Bowel preparation

1. abstain from all food and drink 4-6 hours before the exam

2. patients drink about 1.5 L of oral contrast over 30-60 minute

   • adequate luminal distension is necessary as collapsed bowel loops may mimic pathology

   • CT enterography utilizes negative or neutral oral contrast ^1-3

     • attenuation similar to that of water - e.g. water, PEG, mannitol, methylcellulose, locust bean gum, and low-density barium sulphate preparations (Volumen, 0.1% W/V) 

Fluid distension of the small bowel allows better assessment of mucosal enhancement, mural thickness as well as mesenteric vasculature, this is important especially in the evaluation of Crohn disease ².​

Procedure

• CT scanning is ideally performed on a multidetector computed tomography (MDCT) scanner

• intravenous contrast

  • Crohn disease, celiac disease, postoperative adhesions, radiation enteritis, and scleroderma: a single enteric phase where peak mucosal enhancement is achieved is sufficient - either enteric phase (45-50s) or portal venous phase (60-70s)

  • small bowel tumors: an additional arterial phase can be performed, in particular for the assessment of hypervascular lesions (e.g. NETs) 

  • in cases of suspected GI bleeding, pre-contrast, arterial, portal venous, and delayed phases should be considered

• ​data interpretation with the use of axial and coronal reformatted images for proper evaluation

Findings

• inflammatory bowel disease and its complications e.g. Crohn disease or ulcerative colitis

• small bowel tumors, including benign tumors (e.g. hamartomatous or hyperplastic polyps) or malignant tumors (e.g. adenocarcinoma, NET, lymphoma, gastrointestinal stromal tumors)

• mesenteric ischemia and gastrointestinal tract bleeding

• Celiac disease ^1,2

See also

• CT enteroclysis

• MR enterography

• MR enteroclysis