Interventional radiology of the biliary tract. Transcholecystic intervention. Diagnostic and therapeutic biliary intervention by percutaneous access to the gallbladder is an important new area in interventional radiology. The anatomy of the gallbladder, biliary tree, and surrounding viscera is reviewed in this article as a preliminary to discussion of the diagnostic techniques of aspiration, cholangiography, biopsy, and the therapeutic techniques of gallbladder drainage and cholelithotomy. Recently there has been a bewildering proliferation of procedures aimed at removal, fragmentation, and dissolution of gallbladder stones. Several of these are discussed in this article. Removal of common bile duct stones by percutaneous cholecystostomy also is discussed. 