Spatially selective implementation of the adiabatic T 2 prep sequence for magnetic resonance angiography of the coronary arteries

In coronary magnetic resonance angiography, a magnetization‐preparation scheme for T 2 ‐weighting (T 2 Prep) 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 T 2 Prep would leave the magnetization of blood outside the T 2 Prep volume unaffected and thereby lower the signal‐to‐noise ratio penalty. To test this hypothesis, a spatially selective T 2 Prep was implemented where the user could freely adjust angulation and position of the T 2 Prep 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 T 2 Prep and other prepulses to allow for in‐flow of a larger volume of unsaturated spins. Consistent with numerical simulation, the spatially selective T 2 Prep 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 T 2 Prep. Additionally, a segmental analysis demonstrated that the spatially selective T 2 Prep was most beneficial in proximal and mid segments where the in‐flowing blood volume was largest compared to the distal segments. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.