Perihilar cholangiocarcinoma: What the radiologist needs to know.

Perihilar cholangiocarcinoma (PHC) is a common and highly intractable malignancy of the main biliary tree confluence. PHC is associated with a poor prognosis because of its insidious local spread that makes it challenging to diagnose and assess. Surgical resection remains the standard curative treatment (up to 50% 5-year overall survival after negative-margin resection). More aggressive surgical approaches have recently emerged, pushing the boundaries of PHC resectability at the cost of a higher morbidity. As such, adequate preoperative preparation (i.e., biliary drainage, venous embolization) is now regarded as a critical issue to increase the number of patients amenable to extended liver resection. Thorough imaging plays a pivotal role in the preoperative setting in both PHC resectability assessment and patient preparation to surgery. Despite recent improvement in PHC imaging, its assessment remains challenging and only 50-60% of patients who are scheduled to undergo surgery are ultimately amenable to curative resection. Therefore, a knowledge of available diagnostic and interventional imaging techniques is important to improve PHC management. Herein, we review the various imaging techniques and preoperative radiological interventions such as biliary drainage, portal vein embolization and liver venous deprivation that are available in PHC management focusing on the anatomical and oncological considerations that are crucial to prepare and guide curative surgical resection.