Pancreatitis

Pathology

• Pancreas is edematous and is enlarged.
• Pancreas can show acute inflammation, suppuration hemorrhage and or extensive necrosis.
• There can be extensive peripancreatic inflammation.
• Fluid can accumulate in lesser sac and pleural space, and paracolic gutters.
• Neutrophils infiltrate the edge of the necrotic areas and extend into the adjacent lobules of fat and produce fat necrosis.
• Calcification can be seen in chronic pancreatitis.

An autopsy specimen consisting of the stomach (A), spleen (B), pancreas (D), and adjacent fat (C) reveals acute inflammation. The pancreas is swollen and hyperemic. Focal areas of green necrosis are present. Small foci of bright yellow, fat necrosis are present. The stomach is folded back so as to reveal its posterior wall and the pancreas.

Chronic Pancreatitis

Calcification in pancreas.

Potential acute complications

• Abscess/pseudocyst
  • As liquefaction of necrotic pancreatic tissue progresses, it will gradually take on the appearance of localized fluid collection - pseudocyst
  • This may be in the region of the pancreas or extend beyond the pancreatic region
• Pancreatic rupture/hemorrhage
• Obstructive jaundice
• Pulmonary complications in severely ill patients - ARDS
• GI obstruction
• Acute renal failure 

Which is the imaging procedure of choice in a suspected case of pancreatitis?

• Plain Film
• Ultrasound
• CT scan with PO and bolus IV contrast
• If the pancreas is necrotic, CT with PO and bolus IV contrast has a sensitivity and specificity of 100 and 100%
• For drainable collections (like a large pseudocyst), options include CT and US
  • Transabdominal ultrasound (S/S = 54/88)
  • CT with PO and bolus IV contrast (S/S = 100/25)

What are the anticipated imaging findings of acute pancreatitis in plain film?

• Abdominal x-ray is not diagnostic, but may show:
  • Calcification in the pancreas
  • Mass from a pseudocyst
  • Sentinel loop: Dilatation of duodenum
  • Colon cut off: Dilated colon to the mid-transverse colon. No air seen beyond splenic flexure. This is due to extension of inflammation along mesocolon.
  • Diffuse ileus ( small bowel dilatation) most commonest
  • Left pleural effusion
    

What are the anticipated imaging findings of acute pancreatitis in CT?

• Enlargement of pancreas due to edema
• Peripancreatic inflammation: linear strands in the peripacreatic fat
• Phlegmon
• Hemorrhagic: Enlarged pancreas with increased density due to hemorrhage
• Necrosis: On contrast enhanced phases the necrotic pancreatic parenchyma will show decreased or no enhancement when compared with normally enhancing viable tissue
• Fluid in the paracolic gutter
• Fluid collections: A simple peripancreatic fluid collection will not have a well-defined capsule
• Pseudocysts: As liquefaction of necrotic pancreatic tissue progresses it will gradually take on the appearance of localized fluid collection...pseudocyst
• Abscesses: Diffusely enlarged pancreas with air pockets

What are the imaging findings of pancreatitis in ultrasound?

• Edematous pancreas
• Gallstones
• Dilated common bile duct
• Pseudocyst
• Due to ileus, pancreas is poorly defined in acute pancreatitis

Image Atlas of Pancreatitis

Normal Pancreas in CT

• The pancreas is in retroperitoneum 12-15 cm long and is located in the epigastrium.
• It is divided into four parts head, neck, body and tail. 
• The head of the pancreas is surrounded by the duodenum as it makes a C-loop around the pancreas. The tail is in the hilus of spleen.
• With contrast enhancement it has the same density as liver and spleen.
• It is recognizable by the splenic vein running along posterior inferior groove.
• The common bile duct traverses through the head of the pancreas and joins with the pancreatic duct at the ampulla of Vater to empty bile into the second or descending part of the duodenum. 

Acute Pancreatitis

Plain Film

Findings:

• Cut off sign

Acute Pancreatitis

Plain Film

Cut off sign and Ileus

• White arrowpoints to transeverse colon cut off at splenic flexure. No air in descending colon.
• TC: Transverse colon
• I: Represents small bowel loops with air suggestive of Ileus

Acute Pancreatitis

CT Findings: Post Contrast

• Diffusely enlarged pancreas with low density from edema

C:  Colon
St: Stomach
P:  Pancreas

Acute Pancreatitis

Phlegmon / Inflammatory mass

• White arrowheads: Phlegmon
• Black arrowhead: Pancreatic calcification
• Large Arrow: Peripancreatic fascial infiltration

St: Stomach

Acute Pancreatitis / Pancreatic necrosis

• Arrow: No enhancement of pancreas with IV contrast
• Arrowheads: Normal enhancement in the tail of Pancreas.

St: Stomach

Acute Hemorrhagic pancreatitis

• Enlarged tail of pancreas
• White arrow: Increased density in the enlarged tail of pancreas due to blood
• Fascial changes adjacent to tail of pancreas due to inflammation

What are the imaging findings of chronic pancreatitis?

• Calcifications in the pancreas
• Pseudocysts
  • As necrotic pancreatic tissue liquefies, it forms a "pseudocyst".
  • This may be in the region of the pancreas or extend beyond the pancreatic region.

Chronic Pancreatitis

Arrowheads point to extensive pancreatic calcification.

Chronic Pancreatitis with Pseudocyst and calcifications

Mass density in pancreas

• White arrow: Psudocyst
• Black arrow: Calcifications

Chronic Pancreatitis with Pseudocyst

CT scan in a patient with chronic pancreatitis and pseudocyst.