MDCT of the pancreas: optimizing scanning delay with a bolus-tracking technique for pancreatic, peripancreatic vascular, and hepatic contrast enhancement.
OBJECTIVE
The purpose of this study was to determine the optimal MDCT scanning delay for peripancreatic arterial, pancreatic parenchymal, peripancreatic venous, and hepatic parenchymal contrast enhancement with a bolus-tracking technique.


METHODS
Three-phase 8-MDCT of the pancreas was performed on 170 patients after administration of 2 mL/kg of 300 mg I/mL contrast medium injected at 4 mL/s to a total dose of 150 mL. Patients were prospectively randomized into three groups with different scanning delays for the three phases (arterial, pancreatic, and venous) after bolus tracking was triggered at 50 H of aortic contrast enhancement: group 1 (5, 20, 45 seconds); group 2 (10, 25, 50 seconds); and group 3 (15, 30, 55 seconds). Mean attenuation values of the abdominal aorta, superior mesenteric artery, pancreatic parenchyma, splenic vein, superior mesenteric vein, portal vein, and hepatic parenchyma were measured. Increases in attenuation values after contrast administration were assessed as change in attenuation value. Qualitative analysis also was performed.


RESULTS
Mean contrast enhancement in the aorta (change in attenuation, 321-327 H) and the superior mesenteric artery (change in attenuation, 304-307 H) approached peak enhancement 5-10 seconds after bolus tracking was triggered. Pancreatic parenchyma became most intensely enhanced (change in attenuation, 84-85 H) 15-20 seconds after triggering, and then the enhancement gradually decreased. Enhancement of the splenic vein and portal vein peaked 25 seconds and that of the superior mesenteric vein peaked 30 seconds after triggering. Liver parenchyma reached 52 H 30 seconds after triggering and reached a plateau (change in attenuation, 58-61 H) at a further scanning delay of 45-55 seconds. Qualitative results were in good agreement with quantitative results.


CONCLUSIONS
For the injection protocol used in this study, optimal scanning delay after triggering of bolus tracking at 50 H of aortic contrast enhancement was 5-10 seconds for the peripancreatic arterial phase, 15-20 seconds for the pancreatic parenchymal phase, and 45-55 seconds for the hepatic parenchymal phase.
Kondo
Hiroshi
H
Department of Radiology, Gifu University School of Medicine, 1-1 Yanagido, Gifu 501-1194, Japan. hkondo@gifu-u.ac.jp
Kanematsu
Masayuki
M
Goshima
Satoshi
S
Miyoshi
Toshiharu
T
Shiratori
Yoshimune
Y
Onozuka
Minoru
M
Moriyama
Noriyuki
N
Bae
Kyongtae T
KT
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001012:Aorta, Abdominal / Q000000981:diagnostic imaging*; D003287:Contrast Media / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D008099:Liver / Q000000981:diagnostic imaging*; D008297:Male; D017538:Mesenteric Artery, Superior / Q000000981:diagnostic imaging*; D008875:Middle Aged; D010179:Pancreas / Q000000981:diagnostic imaging*; D011169:Portal Vein / Q000000981:diagnostic imaging; D011856:Radiographic Image Enhancement / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods*
D003287:Contrast Media