Helical CT without contrast in choledocholithiasis diagnosis

The goal of this study was to determine the diagnostic value of the helical CT without contrast in suspected cases of choledocholithiasis, comparing t his test with endoscopic retrograde cholangiopancreatography (ERCP). Forty patients with possible choledocholithiasis were studied prospectively. Ther e were 23 women and 17 men, ranging in age from 24 to 91 years. Helical CT was performed immediately before ERCP (time interval between the two proced ures was less than 1 h). A biliary area previously selected was studied wit h a technique of pitch 1 and slice thickness of 3.2 mm. Average time was 30 s. Reconstruction with different increments and windows were made. Stone p resence was evaluated in bile duct and Vater's ampulla. Biliary dilation wa s evaluated too. Endoscopic retrograde cholangiopancreatography found stone s in 19 patients and absence of stones in 20. One case was failed, but ston es in bile duct were demonstrated during intraoperative cholangiography. He lical CT demonstrated stones in 15 of the 19 patients with positive ERCP. T here were no false positives with CT. Patients without stones in ERCP were also negative in CT. The patient having the failed ERCP was considered posi tive in CT. The CT sensitivity was 80 % and specificity was 100 %, with an accuracy of 90 %. Helical CT without contrast has sensitivity and specifici ty good enough to be used as a screening technique in patients with suspect ed choledocholithiasis.