4.5 Magnetic Resonance Imaging（MRI）
In recent years，MRI has been refined so as to become an ideal，noninvasive imaging technique.With appropriate contrast media，ultra-fast MRI can now provide simultaneous information on the morphology，ductal conditions（MRCP）and blood vessels in pancreatic lesions.MRCP is particularly good at imaging the pancreatic duct when it is dilated.Agreement is best when significant pancreatic ductal abnormalities are present，and when the pancreatic duct is dilated.With the advent of MRCP，the indications for invasive ERCP have to be redefined—usually being reserved for patients requiring additional interventional endoscopic therapy.
Our standard MR protocol for the evaluation to the pancreas includes T1-weighted fatsuppressed 3D gradient echo，T1-weighted inphase，out-of phase，water and fat gradient echo，T2-weighted single-shot echo-train spin-echo with/without fat suppression，and postgadolinium imaging in the tri-phase（arterial phase，pancreatic parenchymal phase and portal venous phase）.Table 7.4 provides the typical imaging parameters that we employ.
Fig.7.7 Chronic pancreatitis and pancreatic pseudocyst on CT.A 38-year-old male with history of chronic pancreatitis and chronic upper back pain.CECT axial（a，b）images reveal multiple pancreatic calcifications in the head（arrows）and a bilobulated cystic lesion involving the body and tail of the pancreas（arrow）.A 38-year-old male with history of chronic pancreatitis and chronic upper back pain.Contrast CT axial（c）images reveal parenchymal atrophy and a big round cystic lesion with hemorrhage（arrow head）involving the body and tail of the pancreas（arrow）
Fig.7.8 Other findings of chronic pancreatitis on CT.CECT axial（a）image shows the pancreatic pseudocyst（arrow）and the peripancreatic fascia thickening（arrow head）in the tail of the pancreas.CECT axial（b）image shows the hypo enhanced mass（arrow head）in the head of the pancreas involves the superior mesenteric vein（arrow）
Table 7.4 3.0 TMR dedicated pancreatic protocol parameters(https://www.daowen.com)
Note:T1WI T1-weighted imaging，T2WI T2-weighted imaging，MRCP magnetic resonance cholangiopancreatography，LAVA liver acquisition with volume acceleration，FSE fast sequence echo，SS-FSE single shot fast sequence echo，Four phases water phase，fat phase，in phases，out phases，-no value，TR repetition time，TE echo time，ms millisecond，mm millimeter，FOV field of view，2D 2-dimensional