Abdomen and PelvisLive data

CT Enterography

CT enterography (CTE) is a dedicated small bowel examination that combines large-volume neutral oral contrast with intravenous contrast to distend and evaluate the small bowel wall and mesentery. It is a first-line cross-sectional test for suspected and known Crohn disease, providing both luminal and extraluminal assessment in a single acquisition.

Indications

Known or suspected Crohn disease for detection and grading of active inflammation
Assessment of penetrating complications: fistula, sinus tract, phlegmon and abscess
Small bowel obstruction of suspected inflammatory or neoplastic aetiology
Obscure or occult gastrointestinal bleeding after negative endoscopy
Characterisation of suspected small bowel tumour (e.g. carcinoid, GIST, lymphoma)

Contraindications & Cautions

Severe iodinated contrast allergy without adequate premedication
Significant renal impairment limiting intravenous contrast administration
Complete or high-grade bowel obstruction where oral contrast ingestion is unsafe or precluded by vomiting
Pregnancy (relative; weigh ionising radiation against alternatives such as MR enterography)

Patient Preparation

Fasting for approximately 4-6 hours prior to examination
Ingestion of 1350-2000 mL neutral oral contrast (e.g. 0.1% barium sulphate or polyethylene glycol solution) over 45-60 minutes
Final aliquot of oral contrast immediately before scanning to distend proximal small bowel
Confirm renal function and screen for iodinated contrast allergy before intravenous injection

Technique & Parameters

Supine positioning with scan coverage from diaphragm to symphysis pubis
Intravenous contrast 100-150 mL at 3-4 mL/s with enteric-phase imaging at approximately 45-50 seconds
Thin collimation (≤1.25 mm) reconstructed as 2-3 mm axial and coronal images
Consider low kVp (e.g. 80-100) or spectral technique to accentuate mural hyperenhancement and reduce dose
Antispasmodic administration is optional and not routinely required for CTE

Systematic Review

Evaluate luminal distension segment by segment (duodenum, jejunum, ileum, terminal ileum)
Assess mural thickness, degree and pattern of enhancement, and mural stratification
Inspect mesentery for engorged vasa recta (comb sign), fibrofatty proliferation and lymphadenopathy
Search for penetrating disease: fistulae, sinus tracts, inflammatory masses and abscess
Review solid organs, vasculature and osseous structures for extraintestinal disease

Key Findings & Significance

Active inflammation: mural thickening >3 mm with hyperenhancement and mural stratification (target/bilaminar pattern)
Comb sign: engorged, comb-like mesenteric vasa recta indicating active disease
Fibrofatty proliferation (creeping fat) reflecting chronic disease
Stricture with proximal small bowel dilatation, distinguishing inflammatory from fibrotic components
Penetrating disease: enteroenteric or enterocutaneous fistula, phlegmon and rim-enhancing abscess

Differential Considerations

Ulcerative colitis and indeterminate colitis (predominantly colonic involvement)
Infectious enteritis (e.g. tuberculosis, Yersinia) mimicking terminal ileal Crohn disease
Small bowel neoplasm: adenocarcinoma, lymphoma, neuroendocrine tumour
Ischaemic enteritis and radiation enteritis
NSAID-induced enteropathy and other segmental inflammatory processes

Pearls & Pitfalls

Adequate luminal distension is essential; collapsed loops can mimic or mask mural thickening
Mural stratification with a hyperenhancing mucosa favours active inflammation over pure fibrosis
Low-kVp or dual-energy iodine imaging increases conspicuity of mural hyperenhancement
MR enterography is preferred when repeated follow-up is anticipated to limit cumulative radiation, particularly in young patients

Structured Report

State segments involved, length of disease and presence of skip lesions
Grade active inflammation (mural thickness, enhancement pattern, comb sign)
Describe strictures with upstream dilatation and estimate luminal calibre
Report penetrating complications with location and size of any abscess
Note extraintestinal findings (sacroiliitis, cholelithiasis, urolithiasis) and compare with priors

References

ACR-SAR-SPR Practice Parameter for the Performance of CT Enterography
Radiographics: Guglielmo FF et al. Small Bowel Crohn Disease at CT and MR Enterography
Society of Abdominal Radiology Crohn Disease-Focused Panel consensus recommendations
Bruining DH et al. Consensus Recommendations for Evaluation, Interpretation, and Utilization of CT and MR Enterography, Radiology

Educational clinical decision support only. Protocols vary by institution and equipment; always confirm with a qualified radiologist and local guidelines before clinical use.

CT Enterography

📋 Indications

⛔ Contraindications & Cautions

🧑‍⚕️ Patient Preparation

⚙️ Technique & Parameters

🔎 Systematic Review

🩻 Key Findings & Significance

🧠 Differential Considerations

💡 Pearls & Pitfalls

📝 Structured Report

📚 References