Twenty seven patients with known rectal cancer were evaluated with CT and CT findings were correlated with surgical and pathologic results on the aspect of perirectal fat infiltration and lymph node involvement. The accuracy in assessment of
perirectal
fat infiltration was 77.8% (21 of 27); sensitivity, 73.3% (11 of 13); specificity, 83.3% (10 of 12). In the detection of lymph node involvement, lymph nodes were divided into five groups according to the arterial teritories. Overall accuracy in
the
evaluation of lymph node involvement was 86.7%. Accuracy of peritumoral lymph node involvement was 51.9% (14 of 27); sensitivity, 42.9%(9 of 21); specificity 83.3% (5 of 6). Accuracy of internal iliac lymph node involvement was 88.9% (24 of 27);
sensitivity, 85.7% (6 of 7); specificity, 90.0% (18 of 20). Of the common and external iliac lymph node, accuracy was 100% (27 of 27); sensitivity, 100% (2 of 2); specificity, 100% (25 of 25). Of the aortic bifurcation and mid sacral lymph node,
accuracy was 92.6% (25 of 27); sensitivity, 50% (2 of 4); specificity, 100% (23 of 23). In regard to the inferior mesenteric lymph node, no lymphadenopathy was found on CT and pathologic results. In conclusion, CT has limited value in evaluating
rectal
cancer but with the satisfactory outcome in assessment of perirectal fat infiltration and lymph node, involvement except peritumoral node preoperative CT is useful in the evaluation of rectal cancer.
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