Diverticulitis versus colon cancer: Differentiation with helical CT findings

PURPOSE: To retrospectively determine the computed tomographic (CT) signs a ssociated with diverticulitis or colon cancer, and to prospectively apply t hese signs in the differentiation of these diseases. MATERIALS AND METHODS: Fifty-eight CT scans in cases of proved diverticulit is (n = 27) or colon cancer (n = 31) were evaluated retrospectively by radi ologists (blinded to the proved diagnosis);for the presence or absence of p reviously reported CT findings. These findings were correlated with the pat hologic or final clinical diagnosis. The retrospective findings were applie d in a prospective evaluation with a new set of 72 CT scans. The same five radiologists rendered a diagnosis according to a five-point confidence scal e from definitely benign to definitely malignant. Individual and consensus readings were correlated with the final diagnosis. RESULTS: Retrospectively, pericolonic inflammation (P < .01)and segment inv olve; ment greater than 10 cm (P < .012) were the most significant findings for diverticulitis; pericolonic lymph nodes (P < .0001) and luminal mass ( P < .003) were the most significant findings for colon cancer. Prospectivel y, an unequivocal diagnosis was made correctly in 16 (40%) of 40 cases of d iverticulitis and 21 (66%) of 32 cases of colon cancer. CONCLUSION: When there are no pericolonic lymph nodes adjacent to a segment of colonic wall thickening, with pericolonic inflammatory changes, the mos t likely diagnosis is diverticulitis. When pericolonic lymph nodes are pres ent, with or without pericolonic edema, the most likely diagnosis is colon cancer.