A
bolus is a rapid infusion of high dose
contrast agent. Dynamic and accumulation
phase imaging can be performed after
bolus injection. Since the transit time of the
bolus through the tissue is only a few seconds, high
temporal resolution imaging can be required to obtain sequential images during the wash in and wash out of the
contrast material and, therefore, resolve the first pass of the tracer.
For the same injected dose of
contrast agent the injection rate (and, consequently, the total injected volume) modifies the
bolus
peak profile. Increasing the injection rate produces a sharpening of the peak
(Cmax increase, Tmax decrease,
peak length decrease). At a
low injection rate, the first pass presents a plateau form.
Substantial changes in the
gadolinium concentrations during signal acquisition induce artifacts. Furthermore, the haemodynamic
parameters (
cardiac output, blood pressure) influence
the
bolus profile.
The characteristics of
gadolinium agents are favorable in the early
bolus
phase, whereas the advantages of large complexes (e.g.
blood pool agents) and
ultrasmall superparamagnetic iron oxide (
USPIO) are most evident in the distribution
phase.
•
] and 439 definitions [
]
Further Reading:
Random Page
top
