Han NY, et al. – This research sought to establish and validate a technique for assessing the depth of tumor invasion (DoI) using magnetic resonance imaging (MRI) and to investigate the diagnostic performance of the measured DoI for stratifying tumor (T) classification in patients with distal bile duct cancer according to the new American Joint Committee on Cancer staging system. It was revealed that this newly established technique reliably measured DoI on T2–weighted MRI and can be applied for preoperative T classification of patients with distal bile duct cancer according to the new staging system.