MR-IMAGING OF ANORECTAL CROHN-DISEASE - A PICTORIAL ESSAY

Magnetic resonance (MR) imaging has proved useful in the evaluation of perianal and perirectal lesions resulting from Crohn disease. On T1-w eighted MR images, sinus tracts and fistulas are hypointense due to th eir fluid content; on T2-weighted images, their signal intensity depen ds on their fluid content and the degree of surrounding fibrosis. Othe r pathologic entities, such as abscesses in the ischioanal fossa, may become evident at MR imaging even though they remain hidden at digital examination. Rectal wall thickening and perirectal inflammatory chang es are often seen at MR imaging of the pelvis. The multiplanar capabil ity of MR imaging greatly facilitates the detection of fistulous tract s that extend into the supralevator space. MR imaging can be helpful t o both the surgeon and the gastroenterologist in the assessment of per ianal and perirectal complications arising from Crohn disease and, whe n necessary, in the planning of surgical intervention. MR imaging also recommends itself to the patient because it is noninvasive and does n ot cause discomfort.