title: Diagnostic value of the delayed phase image for iso-attenuating pancreatic carcinomas in the pancreatic parenchymal phase on multidetector computed tomography.
abstract: OBJECTIVE
  To assess the value of the delayed phase (DP) in pancreatic carcinomas which appear iso-attenuating in the pancreatic parenchymal phase (PPP).
  
  
  METHODS
  Fifty-seven preoperative MDCT studies of pancreatic carcinomas were retrospectively reviewed. The size of the tumors, and the Hounsfield unit (HU) of the tumors and pancreatic parenchyma were measured. The tumor-to-pancreas contrast (TPC: |HU [tumor]-HU [normal pancreas]|) was calculated.
  
  
  RESULTS
  Eight cases (14.0%) showed iso-attenuation and 49 showed hypo-attenuation in the PPP. The DP images revealed seven of eight (87.5%) iso-attenuating tumors to be hyper-attenuating. The size of iso-attenuating tumors was smaller than that of hypo-attenuating tumors (mean+/-S.D.: 12.4+/-4.8mm vs. 30.3+/-9.0mm, p<0.0001). In hypo-attenuating tumors, TPC in the PPP (60.2+/-24.6 HU) was higher than those in the portal venous phase (PVP, 40.5+/-23.0 HU, p<0.0001) and DP (18.3+/-11.8 HU, p<0.0001). In contrast, in iso-attenuating tumors, TPC in the DP (26.0+/-4.9 HU) was higher than those in the PPP (9.2+/-3.7 HU, p=0.0003) and PVP (7.1+/-4.7 HU, p=0.001) phases.
  
  
  CONCLUSIONS
  The DP image is helpful in depicting small iso-attenuating pancreatic carcinomas as slightly hyper-attenuating tumors.
authors.affiliation: Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan. Ishigamikousei@aol.com
authors.forename: Kousei
authors.initials: K
authors.lastname: Ishigami
authors.forename: Kengo
authors.initials: K
authors.lastname: Yoshimitsu
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Irie
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Tajima
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Asayama
authors.forename: Akihiro
authors.initials: A
authors.lastname: Nishie
authors.forename: Masakazu
authors.initials: M
authors.lastname: Hirakawa
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Ushijima
authors.forename: Daisuke
authors.initials: D
authors.lastname: Okamoto
authors.forename: Shigenori
authors.initials: S
authors.lastname: Nagata
authors.forename: Yunosuke
authors.initials: Y
authors.lastname: Nishihara
authors.forename: Koji
authors.initials: K
authors.lastname: Yamaguchi
authors.forename: Akinobu
authors.initials: A
authors.lastname: Taketomi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Honda
mesh_terms: D000230:Adenocarcinoma / Q000000981:diagnostic imaging*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007479:Iopamidol; D008297:Male; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods*
chemical_list: D003287:Contrast Media; D007479:Iopamidol