Phase-velocity cine magnetic resonance imaging measurement of pulsatile blood flow in children and young adults: In vitro and in vivo validation

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, conv enience, or anatomic localization, This study examined the accuracy of a co mmercially available phase-velocity cine magnetic resonance imaging (PVC MR I) technique to quantify flow rate in a pulsatile flow phantom. In addition , the equivalence of PVC MRI measurements of pulmonary and systemic flow wa s evaluated in children and adults without any pathologic shunt. Using a pu lsatile flow phantom, volume flow rates measured by PVC MRI were compared t o 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 techniq ues (y = 1.02x - 0.02, r = 0.99, Bland-Altman bias = -0.045 L/min, 95% limi ts 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 measuremen t 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 0.85-1.1 9). 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 techniqu e to quantify pulsatile blood flow at a specific location. It can be used t o noninvasively calculate Q(P) and Q(s) under normal flow conditions.