International Scholarly Research Notices

Review Article

Imaging of Focal Autoimmune Pancreatitis and Differentiating It from Pancreatic Cancer

Table 2

Imaging features of focal AIP and PC.


Investigation	Focal AIP	Pancreatic cancer

Dual phase CT	Decreased enhancement in pancreatic phase, normal or delayed enhancement in hepatic phase. Enhanced duct sign	Decreased enhancement in pancreatic phase, decreased or minimal increase in enhancement in hepatic phase.

MRI	Speckled appearance within hypointense lesion.	Target-like lesion with upstream dilatation of MPD.
	Low diffusion coefficient on DW-MRI	High diffusion coefficient on DW-MRI.

¹⁸FDG-PET CT	Diffuse FDG uptake	Focal FDG uptake.
	Uptake in salivary gland and kidney

ERP/pancreatography	Long segment narrowing of MPD > 3 cm, skip lesions, upstream dilatation of MPD < 5 mm, side branch dilatation from narrowed MPD.	Complete MPD obstruction, short segment narrowing <3 cm, upstream dilatation of MPD > 5 mm.

ERC/cholangiography	Lower bile duct stenosis smooth margins, gradual and symmetric narrowing, and fully visible lumen or hourglass appearance.	Short segment stenosis irregular margins, complete obstruction.
	Intrahepatic biliary stricture.

EUS	Hyperechoic spots in a hypoechoic mass and the duct-penetrating sign.	Hypoechoic mass with inhomogeneous pattern. Low contrast uptake index on CHE-EUS.
	Delayed enhancement in CHE-EUS.
	Increased thickness of CBD with “sandwich pattern”
	Peripancreatic lymphadenopathy

EUS elastography	Strain ratio <4, hue histogram value <175	High strain ratio >18, hue histogram value >175.

EUS-FNA, EUS-TCB	High stromal cellularity with lymphoplasmacytic infiltrates.	Features of carcinoma.
	High immunochemical staining with IgG4.

CT: computed tomography; MRI: magnetic resonance imaging; DW-MRI: diffusion weighted magnetic resonance imaging; MPD: main pancreatic duct; CBD: common bile duct; FDG PET: 18 fluro deoxyglucose positron emission tomography; EUS: endoscopic ultrasound; CHE-EUS: contrast harmonic echo endoscopic ultrasound; EUS-FNA: endoscopic fine needle aspiration cytology; EUS-TCB: endoscopic trucut biopsy.