54
Bolus Tracking
The Basics
The administration of intravenous (IV) contrast
material during spiral scanning improves the detection
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. Therefore,
it is essential to initiate the acquisition with the correct
start delay. Since Multislice spiral CT can provide much
faster speed and shorter acquisition time, it is even
more critical to get the right timing to achieve optimal
results (Fig.1a,1b).
The dynamics of the contrast enhancement is
determined by:
• Patient cardiac output
• Injection rate (Fig. 2a, 2b)
• Total volume of contrast medium injected
(Fig. 3a, 3b)
• Concentration of the contrast medium (Fig. 3b, 4a)
• Type of injection – uni-phasic or bi-phasic
(Fig. 4a, 4b)
• Patient pathology
Fig. 1a: Longer scan time Fig. 1b: Shorter scan time
40 s scan 10 s scan