4.4 CT Findings
4.4.1 Morphology
Inflammatory disease of pancreas characterized by irreversible damage to morphology and function.The size of the pancreatic gland，initially normal，becomes progressively smaller due to an increasing parenchymal atrophy characterized as uniform and diffuse（Fig.7.3a，b）.In extreme cases，the parenchyma may not be visible.Pancreas increased in size with inflammation，edema and cyst.
4.4.2 Pancreatic Duct
The spectrum of changes in the pancreatic duct are broad including dilatation，stricture，stenosis，intraductal calculi，occasionally side branch duct dilatation（“chain of lakes”or“string of pearls”appearance）（Fig.7.4a-c）.There may be stones inside the lumen of the main duct，sometimes the Santorini duct and the minor ducts.These stones arise from calcium deposits along the intraductal protein plugs.
4.4.3 Inflammatory Mass
Some patients with CP may have more than one mass-like lesion in the pancreas.The inflammatory mass may occur anywhere within the pancreas but is most common in the head of the gland.Due to fibrosis，the mass is hypo enhanced.The inflammatory mass may be associated with bile duct obstruction or duodenal obstruction，main pancreatic duct obstruction，or compression of the portal vein or superior mesenteric vein，thus mimicking most of the imaging features of pancreatic malignancy（Figs.7.5a-c and 7.6a-c）.
Table 7.3 Multidetector CT dedicated pancreatic protocol parameters
Note:FOV field of view
Fig.7.3 Chronic pancreatitis on CT.CECT axial images（a，b）show a dilated pancreatic duct，multiple calcifications（arrows）throughout the pancreas，and parenchymal
Fig.7.4 Chronic pancreatitis on CT.CECT axial image（a）images show calcifications（arrow）and pseudocyst（arrow head）in the head of the pancreas，CECT axial（b）and coronal（c）images show irregular dilatation of the main pancreatic duct up to the level of the neck（arrow），as well as dilatation of the intra-and extrahepatic biliary system（arrow heads）
Fig.7.5 Mass-forming pancreatitis on CT.CECT axial（a，b）images show the hypo enhanced and ill-defined mass（arrow head）in the head of the pancreas.Presence of calcification in the pancreatic head suggests underlying chronic pancreatitis in this patient.There are extreme fluid accumulation in the peripancreatic region.CECT axial（c）image shows the pancreas is reduced in size in the bodytail with the irregular dilatation of the main pancreatic duct (https://www.daowen.com)
Fig.7.6 Mass forming pancreatitis on CT.CECT axial（a）images show the hypo enhanced and ill-defined mass（arrow head）in the head of the pancreas.Presence of calcification and many retention cysts in the pancreatic head suggests mass forming pancreatitis in this patient.CECT axial（b）image shows parenchymal atrophy and the irregular dilatation of the pancreatic duct and its side branches.Photography of the gross specimen（c）reveals an illdefined mass（arrows）in the pancreatic head
4.4.4 Pancreatic Pseudocysts
On CT，pseudocysts are round or oval in shape and have a relatively thin or thick capsule，which can calcify（Fig.7.7a，b）.The pseudocysts may locate anywhere.They contain fluid which is less than 15 Hounsfield units（HU）；higher fluid attenuation values of 40-50 HU indicate intra cystic hemorrhage.Pseudocysts vary significantly in size and may communicate with the pancreatic duct.
4.4.5 Other Feathers
The other findings include（1）thickening of peripancreatic fascia（with acute attack），（2）the obstructive cholangiectasis（3）splenic vein thrombosis，splenomegaly，varices，and（4）may progress to thrombosis of portal vein（Fig.7.8a，b）.