18 F-FDG PET/CT in the diagnosis and systemic evaluation of autoimmune pancreatitis

Objective To investigate the role of 18 F-fluorodeoxyglucose positron emission tomography/ computed tomography (18 F-FDG PET/CT) in diagnosing of autoimmune pancreatitis (AIP) and systemic evaluation.Methods Twenty AIP patients who underwent 18F-FDG PET/CT whole-body examination in Department of Nuclear Medicine,Changhai Hospital from August 2010 to February 2013 were analyzed retrospectively.The morphology and metabolic characteristics of pancreatic and extra-pancreatic lesions (EPLs) were analyzed.Results The mean age of 20 AIP patients (17 male and 3 female) was 60 years old.The main clinical features were abdominal pain or discomfort,jaundice,and repeated steatorrhea.Two patients were detected during routine health check-up.Elevated serum IgG levels were found in 15 cases,and elevated serum IgG4 was detected in 17 cases,and elevated serum CA19-9 was found in 8 cases.The maximumstandardized uptake value (SUVmax) of the pancreas of the 20 patients were significantly increased,and the SUVmax was 5.09 ± 2.10 (2.71 ～ 11.88),and it was 5.14 ± 2.25 in early scanning,and it increased to 6.23 ±2.77 after delayed scanning,and the retention index was 21.20％.Morphologically,diffuse type was found in 12 cases,segmental enlargement type in 3 cases,mixed type in 4 cases,multifocal enlargement in 1 case.Extra-pancreatic lesions were observed in 19 cases,which including cholangitis (n =8) ; sialosis with increased metabolism (n =6) ; lymphadenectasis with increased FDG uptake (n =13) ; interstitial pneumonia or nodule (n =8) ; inverted "V" shaped high FDG uptake foci in prostate (n =11) ; enlarged duodenal papilla with increased metabolism (n =3) ; retroperitoneal fibrosis (n =2) ; ulcerative colitis with segmental increased metabolism (n =2).Conclusions 18 F-FDG PET/CT can show the morphology and metabolic characteristics of pancreatic lesions of AIP,and detect the extra-pancreatic lesions as well.It helps in diagnosis and wholebody evaluation of AIP. Key words: Pancreatitis, chronic ;  Autoimmune diseases ;  Tomography, emission-computed; Tomography, X-ray computed;  Deoxyglucose