Scanner User Manual

Workflow Information
45
Contrast Medium
The Basics
The administration of intravenous (IV) contrast mate-
rial during spiral scanning improves the tissue charac-
terization and characterization of lesions, as well as the
opacity of vessels. The contrast scan will yield good
results only if the acquisition occurs during the optimal
phase of enhancement in the region of interest. There
-
fore, it is essential to initiate the acquisition with the
correct start delay. Since multislice spiral CT can pro
-
vide much faster speed and shorter acquisition time, it
is even more critical to get the right timing to achieve
optimal results.
The dynamics of the contrast enhancement is deter-
mined by:
• Patient cardiac output
•Injection rate
• Total volume of contrast medium injected
• Concentration of the contrast medium
• Type of injection – uni-phasic or bi-phasic
• Patient pathology
Longer scan time Shorter scan time
40 s scan
10 s scan
C2-025.630.01.01.02_APPLICATIONGUIDE_SPIRIT.book Page 45 Friday, April 8, 2005 9:55 AM