The purpose of this study was to investigate the ability of transcutaneous three-dimensional US cholangiography to depict the biliary tree in malignant obstruction, compared with that of MRCP and direct cholangiography.

Three-dimensional US and MRCP and direct cholangiography were performed in 40 patients with suspected malignant biliary obstruction. Diagnostic quality of the images, presence, level, and cause of ductal obstruction were assessed in a prospective, blinded fashion. The results were correlated with consensus interpretation (3 investigators), intra-operative findings, and histopathology or clinical follow-up.

Three-dimensional US produced cholangiographic images of diagnostic quality. The appearance of these images was similar to that of MRCP or ERCP/percutaneous transhepatic cholangiography images. All modalities were highly sensitive in the detection of biliary dilatation. The accuracy of 3-dimensional US, MRCP, and ERCP/percutaneous transhepatic cholangiography in determining the level of obstruction was, respectively, 92%, 95%, and 98%. Transcutaneous 3-dimensional US and MRCP accurately identified the cause of obstruction in, respectively, 90% and 95% of cases. Direct cholangiography revealed the correct diagnosis in 95% of the patients.

Three-dimensional US cholangiography is a new, noninvasive method with the capability to produce diagnostic cholangiograms. Three-dimensional US cholangiography may be used increasingly as an initial test to select patients who require further diagnostic evaluation by MRCP or therapeutic ERCP.