Combined Outer Volume Suppression and T-2 Preparation Sequence for Coronary Angiography

Abstract

Purpose: To develop a magnetization preparation sequence for simultaneous outer volume suppression (OVS) and T-2 weighting in whole-heart coronary magnetic resonance angiography. Methods: A combined OVS and T-2 preparation sequence (OVS-T-2 Prep) was designed with a nonselective adiabatic 90 degrees tipdown pulse, two adiabatic 180 degrees refocusing pulses, and a 2D spiral -90 degrees tipup pulse. The OVS-T-2 Prep preserves the magnetization inside an elliptic cylinder with T-2 weighting, while saturating the magnetization outside the cylinder. Its performance was tested on phantoms and on 13 normal subjects with coronary magnetic resonance angiography using 3D cones trajectories. Results: Phantom studies showed expected T-2-dependent signal amplitude in the spatial passband and suppressed signal in the spatial stopband. In vivo studies with full-field-of-view cones yielded a passband-to-stopband signal ratio of 3.18 +/- 0.77 and blood-myocardium contrast-to-noise ratio enhancement by a factor of 1.43 +/- 0.20 (P < 0.001). In vivo studies with reduced-field-of-view cones showed that OVS-T-2 Prep well suppressed the aliasing artifacts, as supported by significantly reduced signal in the regions with no tissues compared to the images acquired without preparation (P < 0.0001). Conclusion: OVS-T-2 Prep is a compact sequence that can accelerate coronary magnetic resonance angiography by suppressing signals from tissues surrounding the heart while simultaneously enhancing the blood-myocardium contrast. (C) 2014 Wiley Periodicals, Inc.