Optimization of a blood pool contrast agent injection protocol for MR angiography.
OBJECTIVE
To design an ideal first-pass profile for MR angiography (MRA) by optimizing a multiphasic injection protocol based on two experimental animal models.


METHODS
An equivalent contrast-enhanced (CE) MRA injection protocol was developed with controlled injection modalities (injection rate, volume, and dose) in rabbits and pigs. P792, a blood pool contrast agent, was injected in 17 male New Zealand rabbits and five farm pigs with variable injection schemes (mono- and multiphasic). From the gadolinium (Gd) blood concentration data, a simulation of an MR acquisition was performed to evaluate the impact of such an injection protocol on MR arterial signal and to select the best injection protocol.


RESULTS
An empirical relationship between the arterial peak concentration and the injection parameters was found in the rabbits and pigs, allowing precise prediction of the first-pass profile. Of the four injection scheme strategies tested (standard bolus and bi-, tri-, and multiphasic injection protocols), the multiphasic "ramp" injection protocol provided the most optimal contrast agent pharmacokinetics with a durable plateau of concentration.


CONCLUSIONS
Ramp injection protocol provides an optimized first-pass profile for CE-MRA.
Robert
Philippe
P
Guerbet Research, Roissy, France. philippe.robert@guerbet-group.com
Violas
Xavier
X
Santus
Robin
R
Le Bihan
Denis
D
Corot
Claire
C
D000818:Animals; D003287:Contrast Media / Q000008:administration & dosage / Q000493:pharmacokinetics*; D006571:Heterocyclic Compounds / Q000008:administration & dosage / Q000493:pharmacokinetics*; D007267:Injections / Q000379:methods*; D018810:Magnetic Resonance Angiography; D008297:Male; D009942:Organometallic Compounds / Q000008:administration & dosage / Q000493:pharmacokinetics*; D011817:Rabbits; D013552:Swine
D003287:Contrast Media; D006571:Heterocyclic Compounds; D009942:Organometallic Compounds; C435266:contrast agent P792