Diagnostic value of the delayed phase image for iso-attenuating pancreatic carcinomas in the pancreatic parenchymal phase on multidetector computed tomography.
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.
Ishigami
Kousei
K
Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan. Ishigamikousei@aol.com
Yoshimitsu
Kengo
K
Irie
Hiroyuki
H
Tajima
Tsuyoshi
T
Asayama
Yoshiki
Y
Nishie
Akihiro
A
Hirakawa
Masakazu
M
Ushijima
Yasuhiro
Y
Okamoto
Daisuke
D
Nagata
Shigenori
S
Nishihara
Yunosuke
Y
Yamaguchi
Koji
K
Taketomi
Akinobu
A
Honda
Hiroshi
H
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*
D003287:Contrast Media; D007479:Iopamidol