Different diagnostic methods for biliary tract cancer: A review

Abstract

Cholangiocarcinoma (CCA) is a primary malignant tumor originating from the epithelium of the bile duct mucosa. It is the second most common primary tumor of the liver and biliary tract. Based on tumor location, CCA is classified as intrahepatic and extrahepatic. Clinical diagnosis relies on imaging techniques (ultrasonography, computed tomography [CT], magnetic resonance imaging [MRI]), while the final diagnosis is confirmed through histopathological examination of biopsy, brush swab, or post-operative samples. Imaging plays a critical role in diagnosing, staging, and guiding the treatment of biliary cancers. Key imaging methods include magnetic resonance cholangiopancreatography (MRI with MRCP), endoscopic retrograde cholangiopancreatography, endoscopic ultrasound (EUS), and positron emission tomography (PET). Selecting the most suitable diagnostic tool is challenging due to the distinct properties of each method, which are tailored to different diseases and stages of diagnosis or treatment. For example, MRCP provides superior visualization of biliary tract narrowing/dilatation compared to direct cholangiography (ERC) and is more effective in assessing tumor extent. Ultrasound is useful for initial evaluation of bile duct and gallbladder tumors and for identifying bile duct dilatation. CT is effective for detecting focal lesions and staging cancer progression, while MRI is considered the gold standard for tumor visualization. EUS offers a detailed assessment of extrahepatic bile ducts, gallbladder, hepatic hilar structures, local lymph nodes, and vessels. Although ERC allows biopsy or smear collection, it does not assess tumor extent. PET is valuable for detecting distant metastases, monitoring treatment efficacy, and evaluating recurrence. This review focuses on the role of various imaging techniques in the diagnosis, staging, treatment response prediction, and therapy of CCA.

Keywords

Cholangiocarcinoma / Biliary tract cancer / Image-guided therapeutics