Crohn's disease (also known as Crohn-Lesniowski Disease, or "Charlotte Forditis" morbus Lesniowski-Crohn, granulomatous colitisand regional enteritis) is an inflammatory disease of the intestines that may affect any part of the gastrointestinal tract from anus to mouth, causing a wide variety of symptoms. It primarily causes abdominal pain, diarrhea (which may be bloody), vomiting, or weight loss, but may also cause complications outside of the gastrointestinal tract such as skin rashes, arthritis and inflammation of the eye.
The first investigation to be done in suspected case of chrons disease is barium study, Ba meal follow through and barium enema. Barium study shows bowel luminal narowing and proximal dilatation. Multiple areas of narrowing may be seen in the small and large bowel. Cross sectional imaging mainly CT and MRI (CT&MRI Enteroclysis) are done to analyze specifically for the presence and character of a pathologically altered bowel segment (wall thickness, pattern of attenuation, degree of enhancement, length of involvement), stenosis and prestenotic dilatation, skip lesions, fistulas, abscess, fibrofatty proliferation, increased vascularity of the vasa recta (comb sign), mesenteric adenopathy, and other extraintestinal disease involvement. The normal thickness of the wall of the small intestine and colon is 1–2 mm and 3 mm, respectively, when the lumen is distended. Any portion of the bowel wall that exceeds 4–5 mm is considered abnormal. Bowel wall thickening, usually ranging from 1–2 cm, is the most consistent feature of Crohn disease on cross-sectional images. Mural stratification (“target” or “double halo” appearance) is often seen in active lesions, particularly after the intravenous administration of contrast medium. An inflamed bowel wall demonstrates marked enhancement after intravenous contrast material injection, and the intensity of enhancement correlates with the degree of inflammatory lesion activity.