[Role of magnetic resonance imaging in preoperative assessement of hilar cholangiocarcinoma].

Magnetic resonance cholangiopancreatography is a non-invasive imaging, highly performant in detecting and locating biliary stenosis and in predicting its malignancy. The combination of two and three-dimensional MRI sequences is recommended to assess a biliary obstacle. Cholangiopathies are the main differential diagnosis of cholangiocarcinomas. In addition to bile duct abnormalities beyond the stenosis, the predictive signs of malignancy are: asymmetric irregular luminal narrowing (longer than 3mm and thicker than 13mm), abrupt discontinuation of stenosis, and enhancement superior to that of the adjacent hepatic parenchyma during arterial and portal acquisitions. Diffusion sequences improve the sensitivity of biliary stenosis detection. Moreover, restriction of diffusion is useful for distinguishing malignant from benign stenosis. Combining Magnetic resonance cholangiopancreatography, late LAVA and diffusion sequences improves the sensitivity of detection of a possible biliary extension without significant specificity. MRI with gadolinium chelate injection is efficient in assessing vascular extension of cholangiocarcinomas. However its accuracy remains lower than that of Ct-scan. To assess hepatic, lymphatic and peritoneal extensions of cholangiocarcinomas, it is fundamental to combine diffusion and dynamic MRI sequences.