title: Assessment of chronic pancreatitis: utility of diffusion-weighted MR imaging with secretin enhancement.
abstract: OBJECTIVE
  To retrospectively measure and compare changes in pancreatic apparent diffusion coefficient (ADC) following secretin administration in patients with and those without chronic pancreatitis (CP) who underwent magnetic resonance (MR) cholangiopancreatography with diffusion-weighted (DW) imaging.
  
  
  METHODS
  This retrospective HIPAA-compliant study was approved by the authors' institutional review board, with waiver of informed consent. Eighty-nine patients were categorized by the referring gastroenterologist as having no CP (n = 37), mild CP (n = 33), or severe CP (n = 19) on the basis of Cambridge criteria and/or clinical course. Mean age was 52.2 years (range, 21-82 years) in women and 54.3 years (range, 32-81 years) in men. Patients underwent 1.5-T MR cholangiopancreatography, including DW sequences (b = 0, 100, and 400 sec/mm(2)) performed serially for 10 minutes after secretin injection. Severity level of CP was analyzed for sex (Fisher exact test) and age (analysis of variance) differences. Pairwise comparisons of mean ADCs for each parameter (no CP vs mild CP, no CP vs severe CP, mild CP vs severe CP) were performed (Mann-Whitney test). Threshold values of non-secretin-enhanced ADC for pancreatitis discrimination were calculated with receiver operating characteristic analysis. P < .05 was considered to show a significant difference.
  
  
  RESULTS
  Patients with severe CP were more likely to be men than were those without pancreatitis; there were no significant age differences between groups. Mean nonenhanced and maximum secretin-enhanced ADCs were higher in patients without CP than in those with mild or severe CP but did not vary between those with mild and severe CP. Percentage increase in ADC after secretin injection and time to peak ADC did not vary among groups. An ADC of less than 179 x 10(-5) mm(2)/sec was optimal for delineating normal pancreas from CP groups.
  
  
  CONCLUSIONS
  In symptomatic patients, baseline pancreatic ADC obtained with DW imaging prior to secretin administration may aid in diagnosis of CP and assessment of its severity; ADC response to secretin administration may be less useful.
authors.affiliation: Department of Radiology, Indiana University School of Medicine, 550 N University Blvd, Indianapolis, IN 46202, USA. makisik@iupui.edu
authors.forename: M Fatih
authors.initials: MF
authors.lastname: Akisik
authors.forename: Alex M
authors.initials: AM
authors.lastname: Aisen
authors.forename: Kumar
authors.initials: K
authors.lastname: Sandrasegaran
authors.forename: S Gregory
authors.initials: SG
authors.lastname: Jennings
authors.forename: Chen
authors.initials: C
authors.lastname: Lin
authors.forename: Stuart
authors.initials: S
authors.lastname: Sherman
authors.forename: John A
authors.initials: JA
authors.lastname: Lin
authors.forename: Magnus
authors.initials: M
authors.lastname: Rydberg
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D049448:Cholangiopancreatography, Magnetic Resonance; D038524:Diffusion Magnetic Resonance Imaging; D017352:Echo-Planar Imaging; D005260:Female; D005583:Fourier Analysis; D006801:Humans; D007089:Image Enhancement; D008297:Male; D008875:Middle Aged; D010179:Pancreas / Q000473:pathology; D010183:Pancreatic Ducts / Q000473:pathology; D050500:Pancreatitis, Chronic / Q000175:diagnosis*; D012189:Retrospective Studies; D012633:Secretin / Q000008:administration & dosage; D012680:Sensitivity and Specificity; D012737:Sex Factors
chemical_list: D012633:Secretin