OBJECTIVETo evaluate the value of spiral computed tomography in the preoperative assessment of the degree of tumor infiltration in mesorectum and circumferential resection margin status of rectal cancer compared with large tissue slice technique.

METHODSFifty-seven patients with rectal cancer diagnosed by fiber colonoscopy and pathology from March 2007 to December 2007 underwent preoperative 64-layers spiral CT examination. The degree of tumor infiltration in mesorectum and circumferential resection margin status were evaluated. Large tissue slice technique was applied in the pathologic study after the total mesorectal excision of the rectum to determine the degree of tumor infiltration in mesorectum and the circumferential resection margin status. The spiral CT findings were compared with pathologic results. The accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the CT results were assessed respectively.

RESULTSThe overall spiral CT accuracy was 93.0% (53/57) for the degree of tumor infiltration in mesorectum, and it was 94.7%, 94.7% and 96.5% for degree I, II, III infiltration, respectively. Fifty-three cases (93.0%) were accurately predicated with the circumferential resection margin status. The sensitivity, specificity, PPV and NPV of spiral CT measurement was 80.0%, 97.6%, 92.3% and 93.2%, respectively, and was consistent well with the histopathological diagnosis.

CONCLUSIONSSpiral CT provides accurate preoperative assessment for the degree of tumor infiltration in mesorectum and circumferential resection margin status of rectal cancer.