Biliary imaging: a review

Abstract

For practitioners of endoscopic retrograde cholangiopancreatography (ERCP), the times are certainly “a-changin.” Until recently, ERCP was the gold standard for imaging the bile ducts. Noninvasive imaging was confined to transcutaneous ultrasound (TUS), computed tomography (CT) scanning, and radionuclide gallbladder and biliary scans, with percutaneous transhepatic cholangiography (PTC) and IOC (formerly T-tube cholangiography) being the other invasive options. In the last decade, however, “young pretenders” to the ERCP “throne” have emerged: specifically, magnetic resonance imaging (MRI), multidetector helical CT (MDCT) cholangiography, and endoscopic ultrasound (EUS). It is not so long ago that MRI was considered to have no future in the abdominal cavity. However, the abdominal MRI naysayers failed to anticipate the exponential growth of this fledgling technology. Magnetic resonance cholangiopancreatography (MRCP) now rivals ERCP in sensitivity and specificity in many situations. ERCP remains the principal nonsurgical therapeutic approach for mechanical obstruction of the biliary and pancreatic ducts, with PTC and allied techniques (e.g., percutaneous biliary drainage [PBD]) being reserved for ERCP failures and situations in which ERCP is not attempted (e.g., after Roux-en-Y biliary diversion). In most endoscopy units, ERCP has evolved into a mainly therapeutic modality, with a variety of noninvasive (or less invasive) imaging techniques being used for diagnosis. This review will explore the changing face of biliary imaging, with particular emphasis on ERCP, MRCP, and MDCT cholangiography.