title: Diffusion-weighted magnetic resonance imaging of pancreatic adenocarcinomas: association with histopathology and tumor grade.
abstract: OBJECTIVE
  To evaluate the utility of diffusion-weighted magnetic resonance imaging (DWI) in pancreatic ductal adenocarcinoma with various grades of differentiation.
  
  
  METHODS
  Following Institutional Review Board (IRB) approval, 21 consecutive patients with surgical pathology-proven pancreatic adenocarcinomas were retrospectively evaluated. Histopathologic characteristics and grades of differentiation of adenocarcinomas were analyzed. Twenty-one patients without a known history of pancreatic disease were evaluated as the control group. Anatomic MR images and DW images were acquired using 1.5-T MR systems. DWI with b values of 0 and 500 sec/mm² were performed on both patients and control groups. The difference in mean apparent diffusion coefficient (ADC) values among groups of normal pancreatic parenchyma, adenocarcinomas with poor differentiation, and adenocarcinomas with well/moderate differentiation were compared using one-way analysis of variance.
  
  
  RESULTS
  Mean ADCs of pancreatic adenocarcinomas (1.77 ± 0.45 × 10⁻³ mm²/sec) was not significantly lower than that of normal parenchyma (1.98 ± 0.31) (P = 0.09). When adenocarcinomas were subdivided based on grades of differentiation, however, poorly differentiated adenocarcinoma with histopathologic characteristics of limited glandular formation and dense fibrosis had significantly lower ADCs (1.46 ± 0.17) compared to those of well/moderately differentiated adenocarcinomas (2.10 ± 0.42) characterized by neoplastic tubular structures (P < 0.01). Well/moderately differentiated adenocarcinomas with dense fibrosis showed significantly lower ADC values (1.49 ± 0.19) than those with loose fibrosis (2.26 ± 0.30) (P = 0.01).
  
  
  CONCLUSIONS
  Difference in ADC values using DWI between poorly and well/moderately differentiated pancreatic ductal adenocarcinoma may relate to differences in glandular formation and density of fibrosis.
authors.affiliation: Department of Radiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA.
authors.forename: Yi
authors.initials: Y
authors.lastname: Wang
authors.forename: Zongming E
authors.initials: ZE
authors.lastname: Chen
authors.forename: Paul
authors.initials: P
authors.lastname: Nikolaidis
authors.forename: Robert J
authors.initials: RJ
authors.lastname: McCarthy
authors.forename: Laura
authors.initials: L
authors.lastname: Merrick
authors.forename: Laura A
authors.initials: LA
authors.lastname: Sternick
authors.forename: Jeanne M
authors.initials: JM
authors.lastname: Horowitz
authors.forename: Vahid
authors.initials: V
authors.lastname: Yaghmai
authors.forename: Frank H
authors.initials: FH
authors.lastname: Miller
mesh_terms: D000005:Abdomen / Q000473:pathology*; D000368:Aged; D000369:Aged, 80 and over; D021441:Carcinoma, Pancreatic Ductal / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity