What CT Enterography Evaluates
CT enterography is a specialized imaging technique that evaluates bowel wall inflammation, strictures, penetrating complications (fistulas, abscesses), and extraintestinal manifestations of small bowel disease, particularly Crohn's disease.
Primary Imaging Findings
CT enterography systematically assesses three main categories of pathology 1:
Inflammatory Features
- Bowel wall thickening (>4 mm) - detected in 87% of Crohn's cases 2
- Mural hyperenhancement (>10 HU increase) - present in 95% of cases and strongly correlates with active inflammation 2
- Perienteric fat stranding - indicates severity of inflammation 1
- Vascular changes including prominent vasa recta ("comb sign") - seen in 23% of cases 2
- Mural edema and ulcerations - correlate with endoscopic and histologic inflammation severity 1
Stricture Characterization
The examination determines 1:
- Number and location of strictures (proximity to ileocecal valve or ligament of Treitz)
- Length of each stricture
- Degree of upstream bowel dilation
- Critically, whether imaging signs of active inflammation are present or absent - this distinction guides whether medical versus surgical management is appropriate
Penetrating Complications
CT enterography excels at detecting extraintestinal disease 2, 3:
- Fistulas (10-14% of cases) - connections between bowel loops or to other organs
- Abscesses (26% of cases) - fluid collections requiring drainage
- Sinus tracts - blind-ending inflammatory tracks
- Inflammatory masses/phlegmon (21% of cases)
- Free perforation - surgical emergency
Additional Pathology Assessed
Beyond the primary findings, CT enterography evaluates 1:
- Mesenteric venous thrombosis - important vascular complication
- Perianal disease - fistulas or abscesses (though dedicated pelvic MRI is superior)
- Extraintestinal manifestations: sacroiliitis, primary sclerosing cholangitis, avascular necrosis, pancreatitis, nephrolithiasis
Key Limitations
CT enterography cannot visualize mucosal details such as strip ulcers or cobblestone appearance that are visible on barium studies or endoscopy 2. For mucosal assessment, complementary techniques are needed.
Clinical Context
The examination is performed at diagnosis to detect disease beyond endoscopic reach and during monitoring when small bowel or penetrating disease is present 1. Bowel wall thickness demonstrates the best diagnostic accuracy (sensitivity 82%, specificity 74%) among individual CT parameters 4, though combined assessment of multiple features provides optimal diagnostic value 5.