title: Differentiating Mass-Forming Autoimmune Pancreatitis From Pancreatic Ductal Adenocarcinoma on the Basis of Contrast-Enhanced MRI and DWI Findings.
abstract: OBJECTIVE
  The purpose of this study was to assess value of contrast-enhanced MRI, MRCP, and DWI for differentiating mass-forming autoimmune pancreatitis (AIP) from pancreatic ductal adenocarcinoma (PDAC).
  
  
  METHODS
  This study included 15 patients with mass-forming AIP and 79 with PDAC who underwent gadoxetic acid-enhanced MRI with DWI and MRCP. Two radiologists evaluated the MRI findings in consensus. Statistically significant imaging findings were identified through univariate and multivariate analyses, and their diagnostic performance for predicting mass-forming AIP was analyzed.
  
  
  RESULTS
  In the univariate analysis, multiplicity, similar or high signal intensity on portal phase and 3- and 20-minute delayed phase images, homogeneous enhancement, no peripancreatic fat infiltration, no internal cystic or necrotic portion, capsulelike rim, no upstream pancreatitis, no vascular invasion, and duct penetrating sign were more frequently observed (p < 0.05) in mass-forming AIP. The apparent diffusion coefficient (ADC) value was also significantly lower for mass-forming AIP than for PDAC (0.96 ± 0.14 versus 1.13 ± 0.23 × 10(-3) mm(2)/s; p < 0.001). The optimal cutoff value of ADC for differentiating mass-forming AIP from PDAC was 0.9407 × 10(-3) mm(2)/s. In multivariate analysis, homogeneous enhancement (p = 0.001), duct penetrating sign (p < 0.001), and ADC value less than 0.9407 × 10(-3) mm(2)/s (p < 0.001) were significant for differentiating mass-forming AIP from PDAC. When two of these three criteria were combined, 80% (12/15) of mass-forming AIPs were identified with specificity of 98.7%. When all three criteria were satisfied, specificity was 100%.
  
  
  CONCLUSIONS
  Contrast-enhanced MRI with MRCP and DWI may be helpful for differentiating mass-forming AIP from PDAC.
authors.affiliation: 1 Department of Radiology, Soonchunhyang University College of Medicine, Bucheon Hospital, Bucheon, Republic of Korea.
authors.forename: Seo-Youn
authors.initials: SY
authors.lastname: Choi
authors.affiliation: 2 Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Ilwon-Ro, Gangnamgu, Seoul, Republic of Korea.
authors.forename: Seong Hyun
authors.initials: SH
authors.lastname: Kim
authors.affiliation: 2 Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Ilwon-Ro, Gangnamgu, Seoul, Republic of Korea.
authors.forename: Tae Wook
authors.initials: TW
authors.lastname: Kang
authors.affiliation: 2 Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Ilwon-Ro, Gangnamgu, Seoul, Republic of Korea.
authors.forename: Kyoung Doo
authors.initials: KD
authors.lastname: Song
authors.affiliation: 3 Department of Radiology, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, Republic of Korea.
authors.forename: Hyun Jeong
authors.initials: HJ
authors.lastname: Park
authors.affiliation: 4 Department of Preventive Medicine, Gachon University Graduate School of Medicine, Incheon, Republic of Korea.
authors.forename: Yoon-Hyeong
authors.initials: YH
authors.lastname: Choi
mesh_terms: D000368:Aged; D001327:Autoimmune Diseases / Q000175:diagnosis*; D021441:Carcinoma, Pancreatic Ductal / Q000175:diagnosis*; D049448:Cholangiopancreatography, Magnetic Resonance; D003287:Contrast Media; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000175:diagnosis*; D010195:Pancreatitis / Q000175:diagnosis*
chemical_list: D003287:Contrast Media; C073590:gadolinium ethoxybenzyl DTPA; D019786:Gadolinium DTPA
keywords: DWI; MRCP; apparent diffusion coefficient; autoimmune pancreatitis; pancreatic ductal adenocarcinoma