MRCP is called magnetic resonance cholangiopancreatography, and it is a technique that uses heavy T2-weighted pulse sequences to show tissue structures with very long T2 relaxation times. In general, substantial organs, such as the liver, spleen and pancreas, have short T2 relaxation times and appear as low signal on heavy T2-weighted sequences. Adipose tissues have moderately long T2 relaxation times, and various fat suppression techniques can be applied to suppress the fat signal. Fast flowing fluid, such as blood flow in the portal vein or hepatic vein, shows signal deficit on the image due to the flow-void phenomenon, and only stationary or relatively stationary fluid shows high signal, while bile in the biliary system belongs to relatively stationary fluid, so MRCP can clearly show the morphological structure of the biliary system.