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 tumour, e.g. neuroendocrine tumour (NET), polyposis syndromes

• coeliac disease: assess for complications such as lymphoma

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

• chronic diarrhoea and/or abdominal pain

• suspected chronic mesenteric ischaemia

Advantages ​

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

Disadvantages 

• exposure to ionising 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 utilises 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, coeliac 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 tumours: 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 tumours, including benign tumours (e.g. hamartomatous or hyperplastic polyps) or malignant tumours (e.g. adenocarcinoma, NET, lymphoma, gastrointestinal stromal tumours)

• mesenteric ischaemia and gastrointestinal tract bleeding

• Coeliac disease ^1,2

See also

• CT enteroclysis

• MR enterography

• MR enteroclysis