TABLE 2.
Imaging findings associated with inflammation in Crohn's disease
| Imaging findings | Description/definition | Detection in techniques |
|---|---|---|
| Segmental mural hyperenhancement | Increased attenuation/signal intensity from contrast‐enhanced scan on bowel segment in comparison with nearby normal bowel segments | CT, MRI, US |
| Wall thickening | Bowel wall thickening >3–5 mm, 3 mm, 3–4 mm from CT, MRI, US, respectively | CT, MRI, US |
| Intramural edema | The grey attenuation layer of the water halo sign in CT represents edema in submucosa; hyperintense signal from fat‐saturated T2‐weighted scan in MRI | CT, MRI |
| Stricture | Luminal narrowing (at least 50% reduction of luminal diameter in CT or MRI, <10 mm in CT or US) in area of Crohn's disease with unequivocal upstream dilation (luminal diameter is >3 and 2.5 cm in CT and US; 1.5‐fold greater than normal loop in MRI) | CT, MRI, US |
| Ulcerations | Appear as small focal breaks in the intraluminal surface of the bowel wall with focal extension of air or enteric enhancement from the inflamed bowel wall | CT, MRI, US |
| Fistulas | Appears as an extra‐enteric tract, with or without internal air or fluid. Including simple/complex fistulas, sinus tract and perianal fistulas | CT, MRI, US |
| Inflammatory mass | Ill‐defined mass‐like process of mixed fat and/or soft tissue attenuation/signal intensity (non‐water attenuation/signal intensity) usually associated with penetrating disease, such as complex fistulas | CT, MRI, US |
| Abscess | Mesenteric/peritoneal/perianal fluid collection with rim enhancement and/or internal air | CT, MRI, US |
| Perienteric edema/inflammation | Increased attenuation (CT) or high fat‐saturated T2‐weighted signal (MR) in mesenteric fat adjacent to abnormal bowel loops | CT, MRI |
| Comb sign | Engorged vessels that supply an inflamed bowel loop | CT, MRI, US |
| Fibrofatty proliferation | Increased fat adjacent to abnormal bowel, displacing bowel loops; usually along mesenteric border, but can be circumferential | CT, MRI, US |
| Adenopathy | Lymph node >1.5 cm (in short axis) | CT, MRI |
Abbreviations: CT, computed tomography; MRI, magnetic resonance imaging; US, ultrasonography.