Phase-Velocity Cine Magnetic Resonance Imaging Measurement of Pulsatile Blood Flow in Children and Young Adults: In Vitro and In Vivo Validation

Abstract.

Quantification of blood flow in vessels provides valuable information that aids management decisions in a variety of cardiac conditions. Current flow measurement techniques are often limited by accuracy, time resolution, convenience, or anatomic localization. This study examined the accuracy of a commercially available phase-velocity cine magnetic resonance imaging (PVC MRI) technique to quantify flow rate in a pulsatile flow phantom. In addition, the equivalence of PVC MRI measurements of pulmonary and systemic flow was evaluated in children and adults without any pathologic shunt. Using a pulsatile flow phantom, volume flow rates measured by PVC MRI were compared to those by a transit-time ultrasound flowmeter over a range of flow rates (1.25–3.5 L/min, 13 trials). Close agreement was found between these techniques (y= 1.02x− 0.02, r= 0.99, Bland–Altman bias =−0.045 L/min, 95% limits of agreement =−0.19–0.10 L/min). Twenty subjects (median age 12.8 years, range 0.7–49 years) with no pathologic shunt underwent PVC MRI measurement of blood flow in the main pulmonary artery (Q _p) and the ascending aorta (Q _s). Data processing time for each location was 20 minutes. The Q _p/Q _s ratio closely approximated unity (mean = 0.99, SD = 0.10, range 0.85–1.19). Interobserver agreement was excellent (Bland–Altman bias = 0.09 L/min, 95% limits of agreement = 0.15–0.33 L/min). PVC MRI is an accurate technique to quantify pulsatile blood flow at a specific location. It can be used to noninvasively calculate Q _p and Q _s under normal flow conditions.