HELICAL CT PNEUMOCOLON TO ASSESS COLONIC TUMORS - RADIOLOGIC-PATHOLOGICAL CORRELATION

OBJECTIVE. The objective of this study was to determine the accuracy o f helical CT pneumocolon in the staging of colonic carcinomas. SUBJECT S AND METHODS. Fifty-two patients (27 men, 25 women; age range, 40-88 years old; mean age, 67 years old) with known or strongly suspected co lonic disorders underwent CT pneumocolon. After bowel cleansing, admin istration of smooth muscle relaxant, and rectal air insufflation, CT p neumocolon was performed with 5-mm collimation, 2.5-mm reconstruction interval, and a pitch of 1.5. Two contrast administration protocols we re used. Twelve patients received 100 ml of IV contrast material that was injected at 3 ml/sec; scan delay was 45 sec. The other 40 patients received 150 ml of contrast material at 5 ml/sec; scan delay was 25 s ec. Images were prospectively evaluated. All patients had pathologic c onfirmation: 46 patients had resections and six patients had endoscopi c biopsies. RESULTS. Diagnostic images were obtained in 47 of 52 patie nts. In the 47 patients, there were 38 colonic carcinomas (one synchro nous), nine diverticular strictures, eight polyps, one ischemic strict ure, and one normal study. Thirty of 38 carcinomas were correctly stag ed by CT. Sensitivity and specificity for serosal infiltration were 10 0% (35/35 carcinomas) and 33% (one of three carcinomas), respectively; sensitivity and specificity for lymph node involvement were 56% (nine of 16 carcinomas) and 95% (21/22 carcinomas), respectively. Four poly ps that were smaller than 5 mm in diameter were not revealed by CT. Tw elve of 14 benign lesions were correctly diagnosed and two were believ ed to be malignant. No malignant lesion was misdiagnosed. CONCLUSION. CT pneumocolon gave an overall staging accuracy of 79% in 38 carcinoma s.