Overview of Current Strategies for Diagnostic Imaging of Biliary Tract and Gallbladder Tumors

Early diagnosis of biliary cancers would be important to improve their prognosis, and accurate staging would help to choose the best possible treatment. However, biliary cancers present specific diagnostic challenges. Imaging modalities, imaging-guided fine-needle aspiration, and endoscopic brush samples play a crucial role in the diagnostic work-up. However, there is no single modality capable of reliably detecting and accurately staging biliary cancers; hence, complementary modalities are usually needed. Transabdominal ultrasound (US) is often the first imaging modality applied to patients with jaundice or nonspecific gastrointestinal complaints. US visualizes bile duct obstruction accurately and is a suitable method for assessing even mild symptoms, and it is noninvasive, nonradiative, and commonly available. If a biliary malignancy is suspected, further investigations are usually performed after US. Magnetic resonance imaging (MRI) and multidetector computed tomography (MDCT) may yield additional information of the tumor and/or its extent. Fast-imaging techniques have made MRI potentially more valuable, and magnetic resonance cholangiography (MRC) is the least invasive mode of cholangiography, which is useful with MRI in the case of biliary obstruction. MDCT can produce multiplanar reconstructions of good quality but it has exposed patients to relatively high dose of radiation. In ambiguous cases, both MRI and MDCT may be needed. Direct cholangiography may provide the most accurate anatomic information of the bile ducts. It is also needed for therapeutic purposes in the case of bile duct obstruction. Further, positron emission tomography (PET), PET/CT, and endoscopic or intraductal US may help in the diagnostic work-up, when available.