Evaluation of the precision of magnetic resonance phase velocity mapping for blood flow measurements

Evaluating the in vivo accuracy of magnetic resonance phase velocity. mappi ng (PVM) is not straightforward because of the absence of a validated clini cal flow quantification technique. The aim of this study was to evaluate PV M by investigating its precision, both in vitro and in vivo, in a 1.5 Tesla scanner In the former case, steady and pulsatile flow experiments were con ducted using an aortic model under a variety of flow conditions (steady : 0 .1-5.5 L/min, pulsatile. 10-75 mL/cycle). In the latter case, PVM measureme nts were taken in the ascending aorta often subjects, seven of which hem ao rtic regurgitation. Each velocity measurement was taken twice, with the sli ce perpendicular to the long axis of the aorta. Comparison between, the mea sured and true flow rates and volumes confirmed the high accuracy of PVM in measuring pou in vitro (p > 0.85). The in vitro precision of PVM was found to be very high (steady: y = 1.00x + 0.02. r = 0.999: pulsatile: y = 0.98x + 0.72. r = 0.997: x: measurement #1, y : measurement #2) and this was con firmed by Bland-Airman analysis. Of great clinical significance was the hig h level of the in vivo precision (y = 1.01x - 0.04. r = 0.993), confirmed s tatistically (p = 1.00). In conclusion. PVM provides repeatable bloodflow m easurements. The high in vitro accuracy and precision, combined with the hi gh in vivo precision, are key factors for the establishment of PVM as the " gold-standard" to quantify bloodflow.