Spatially selective implementation of the adiabatic T2Prep sequence for magnetic resonance angiography of the coronary arteries.
In coronary magnetic resonance angiography, a magnetization-preparation scheme for T2-weighting (T2Prep) is widely used to enhance contrast between the coronary blood-pool and the myocardium. This prepulse is commonly applied without spatial selection to minimize flow sensitivity, but the nonselective implementation results in a reduced magnetization of the in-flowing blood and a related penalty in signal-to-noise ratio. It is hypothesized that a spatially selective T2Prep would leave the magnetization of blood outside the T2Prep volume unaffected and thereby lower the signal-to-noise ratio penalty. To test this hypothesis, a spatially selective T2Prep was implemented where the user could freely adjust angulation and position of the T2Prep slab to avoid covering the ventricular blood-pool and saturating the in-flowing spins. A time gap of 150 ms was further added between the T2Prep and other prepulses to allow for in-flow of a larger volume of unsaturated spins. Consistent with numerical simulation, the spatially selective T2Prep increased in vivo human coronary artery signal-to-noise ratio (42.3 ± 2.9 vs. 31.4 ± 2.2, n = 22, P < 0.0001) and contrast-to-noise-ratio (18.6 ± 1.5 vs. 13.9 ± 1.2, P = 0.009) as compared to those of the nonselective T2Prep. Additionally, a segmental analysis demonstrated that the spatially selective T2Prep was most beneficial in proximal and mid segments where the in-flowing blood volume was largest compared to the distal segments.
Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, Maryland, USA.
Sahar
S
Soleimanifard
Michael
M
Schär
Allison G
AG
Hays
Jerry L
JL
Prince
Robert G
RG
Weiss
Matthias
M
Stuber
D000328:Adult; D000465:Algorithms; D001783:Blood Flow Velocity / Q000502:physiology; D017023:Coronary Angiography / Q000379:methods*; D003326:Coronary Circulation / Q000502:physiology*; D003331:Coronary Vessels / Q000033:anatomy & histology* / Q000502:physiology*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity