Prospective Heart Tracking for Respiratory Motion Compensation in Whole-heart Magnetic Resonance Angiography

Background Electrocardiogram and respiratory navigator (NAV)gated 3D whole-heart magnetic resonance angiography (MRA) acquired with an intravascular gadolinium-based contrast agent and a non-selective inversion recovery (IR) pulse to null the myocardial signal generates a highresolution anatomic dataset allowing for a comprehensive evaluation of intra-cardiac, coronary, and vascular abnormalities [1]. In this technique, an additional IR pulse is also included to selectively restore the signal in the liver, and thus allow NAV tracking of the diaphragm (liver-lung interface). This selective IR pulse, however, excites the blood flowing from veins into the heart creating a bright inflow artifact that hinders image interpretation [2]. Therefore, we sought to develop a prospective respiratory-gating technique (Heart-NAV) that tracks the heart rather than the diaphragm position and eliminates the inflow artifact without compromising image quality.