title: Pancreatic adenocarcinoma: variability of diffusion-weighted MR imaging findings.
abstract: OBJECTIVE
  To compare the apparent diffusion coefficients (ADCs) of pancreatic adenocarcinomas that appear hyperintense with clearly defined borders (clear hyperintense) with those that do not show clear hyperintense borders on diffusion-weighted magnetic resonance (MR) images.
  
  
  METHODS
  Institutional review board approval was obtained and informed consent was waived. Eighty patients with histologically confirmed pancreatic adenocarcinoma (mean tumor size, 32 mm) underwent fat-suppressed single-shot echo-planar 3.0-T diffusion-weighted MR imaging with diffusion gradients (b = 1000 sec/mm(2)). ADC values of the pancreatic adenocarcinomas (n = 80) and proximal (n = 51) and distal (n = 70) pancreas were compared by using the Friedman test, followed by the Wilcoxon signed-rank test, and the difference in serum amylase levels between pancreatic adenocarcinomas with and without clear hyperintensity was evaluated by using the x(2) test.
  
  
  RESULTS
  In 38 of 80 patients, pancreatic adenocarcinomas showed clear hyperintensity relative to the surrounding pancreas; 26 were hyperintense with unclear distal borders; 12, isointense; and four, hypointense. In all patients, the mean ADC (± standard deviation) of the tumors (1.16 × 10(-3) mm(2)/sec ± 0.22) was significantly lower than those of the proximal pancreas (1.33 × 10(-3) mm(2)/sec ± 0.16, P < .001) and the distal pancreatic parenchyma (1.24 × 10(-3) mm(2)/sec ± 0.23, P = .004). No significant difference in ADC was seen between the pancreatic adenocarcinomas without clear hyperintensity and the distal pancreas. The frequency of serum amylase levels greater than 120 U/L (2.00 μkat/L) was significantly higher than in those with clear hyperintense pancreatic adenocarcinomas (P < .001).
  
  
  CONCLUSIONS
  Diffusion-weighted MR imaging was not useful for delineating 47% of pancreatic adenocarcinomas, because of hyperintensity of the pancreatic parenchyma distal to the cancer.
authors.affiliation: Department of Radiology, Kagoshima University Graduate School of Medical and Dental Sciences, 8-35-1 Sakuragaoka, Kagoshima 890-8544, Japan. fukukura@m.kufm.kagoshima-u.ac.jp
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Fukukura
authors.forename: Koji
authors.initials: K
authors.lastname: Takumi
authors.forename: Kiyohisa
authors.initials: K
authors.lastname: Kamimura
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Shindo
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Kumagae
authors.forename: Akihiro
authors.initials: A
authors.lastname: Tateyama
authors.forename: Masayuki
authors.initials: M
authors.lastname: Nakajo
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis* / Q000000981:diagnostic imaging; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016009:Chi-Square Distribution; D003287:Contrast Media; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D007472:Iohexol; D007479:Iopamidol; D008297:Male; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging; D012189:Retrospective Studies; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed / Q000379:methods
chemical_list: D003287:Contrast Media; D007472:Iohexol; D007479:Iopamidol