Acute colitis: differential diagnosis using multidetector CT

•A “comb” sign, small bowel involvement and enlarged lymph nodes are correlated with inflammatory colitis.•An “empty colon” sign, continuous distribution of the abnormalities and the absence of enlarged lymph nodes are correlated with infectious colitis.•MDCT is useful for distinguishing the cause of acute colitis.

AimTo investigate the utility of multidetector CT (MDCT) in helping to establish the underlying cause of acute colitis.Methods and materialsAll patients who had acute colitis with a well-identified cause and underwent abdomen 64-MDCT were included in the study. MDCT images were retrospectively analysed in a blinded fashion and the CT findings were correlated with the eventual aetiological diagnosis.ResultsThe study population included 105 patients. Acute colitis was related to inflammatory bowel disease in 43 cases. MDCT was used to identify six relevant signs of inflammatory colitis: the “comb” sign (p < 0.001), enlarged lymph nodes (p < 0.001), abscess (p = 0.026), fibro-fatty infiltration (p = 0.007), small bowel involvement (p < 0.001), and the absence of an “empty colon” sign (p = 0.045). Multivariate logistic regression analysis identified three independent signs of inflammatory colitis: the “comb” sign, small bowel involvement, and enlarged lymph nodes. Acute colitis was related to bacterial infection in 35 cases. Five signs were significantly associated with infectious colitis: continuous distribution (p = 0.020), an “empty colon” sign (p = 0.002), absence of fat stranding (p = 0.013), and absence of a “comb” sign (p = 0.010) and absence of enlarged lymph nodes (p = 0.035). Multivariate analysis identified three independent signs: the “empty colon” sign and absence of fat stranding and of a “comb” sign. The remaining causes were ischaemic colitis (n = 21) and drug-related colitis (n = 6). MDCT examination provided five relevant signs of ischaemic colitis: fat stranding (p = 0.002), discontinuous distribution (p < 0.001), and absence of enlarged lymph node (p < 0.001), a “comb” sign (p = 0.006) and small bowel involvement (p = 0.037).ConclusionsMDCT provides certain suggestive signs that may be helpful in distinguishing the underlying aetiological cause of acute colitis.