Determination of scan delay time in spiral CT-angiography: utility of a test bolus injection.
OBJECTIVE
The usefulness of a test bolus of contrast medium for predicting the optimal scan delay time in spiral CT-angiography (CTA) was determined.


METHODS
Two axial single level CT studies were performed at the level of the pancreas in 20 patients, first after injection of a 12 ml "test" bolus, second after administration of a 90 ml bolus. The time interval between the start of the test bolus injection and peak aortic enhancement (T-peak) was measured and compared with the time required to reach a 50, 100, and 150 HU level of aortic enhancement after 90 ml bolus injection.


RESULTS
The time required to reach 50, 100, and 150 HU enhancement during the 90 ml bolus was largely variable (mean SD 4.9 s). The T-peak varied between 11 and 32 s (mean 20, SD 6.1 s). There was a strong correlation between the T-peak and the time to the different levels of enhancement during the 90 ml bolus (R2 > or = 0.83). The mean time to 50, 100, and 150 HU enhancement was T-peak -3.3 s (SD 2.5 s), T-peak -1.2 s (SD 2.4 s), and T-peak + 1.3 s (SD 2.4 s).


CONCLUSIONS
The injection of a test bolus improves the timing of a spiral CTA acquisition.
van Hoe
L
L
Department of Radiology, University Hospitals K. U. Leuven, Belgium.
Marchal
G
G
Baert
A L
AL
Gryspeerdt
S
S
Mertens
L
L
D000328:Adult; D000368:Aged; D000792:Angiography; D001027:Aortography; D003287:Contrast Media / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D007275:Injections, Intravenous; D008297:Male; D008875:Middle Aged; D010179:Pancreas / Q000000981:diagnostic imaging; D013162:Splenic Vein; D013997:Time Factors; D014057:Tomography, X-Ray Computed
D003287:Contrast Media