Biliary tract obstruction. The role of spiral CT in detection and definition of disease.

The purpose of this study was to assess the efficacy of spiral computed tomography (CT) in determining the etiology of biliary tract obstruction. Spiral CT studies performed over a 9-month period in 42 consecutive patients with suspected biliary tract obstruction were reviewed. Analysis of scans included localizing the obstruction and then defining a specific etiology. Pertinent associated findings such as porta hepatis or peripancreatic adenopathy, hepatic or peritoneal metastases, and pancreatic pseudocyst or abscess formation were also assessed. Spiral CT demonstrated the level of obstruction in all 30 patients in whom there was biliary tract dilatation. Thirty-two diagnoses were rendered in 30 patients, with specific obstructing lesions identified in 28 instances (88%). Twenty-five (78%) of 32 specific pathological diagnoses were correct. The positive predictive value for neoplasms in the pancreatic head was 100% (n = 17). Two patients with characteristic CT changes of sclerosing cholangitis were diagnosed as having superimposed cholangiocarcinoma, although the results of biopsies for neoplasm were negative. The sensitivity of spiral CT for detection of common duct calculi was 67% (n = 3). Due to optimal contrast enhancement of both hepatic and pancreatic parenchyma, spiral CT enables excellent visualization of the biliary system and provides a specific explanation for biliary tract obstruction in nearly all cases. Spiral CT can usually distinguish neoplastic from nonneoplastic causes of jaundice. When distal common duct obstruction is detected in the absence of an identifiable mass or focal ductal wall thickening, neoplasia is unlikely. It is difficult to exclude sclerosing cholangitis from cholangiocarcinoma on the basis of spiral CT findings, and in these patients, biopsy or close follow-up is recommended to exclude the possibility of a biliary neoplasm.