3-POINT PHASE-CONTRAST VELOCITY-MEASUREMENTS WITH INCREASED VELOCITY-TO-NOISE RATIO

We describe a technique to increase the velocity-to-noise ratio (VNR) of phase-contrast magnetic-resonance velocity images based on making t hree measurements/flow encoding axis rather than the usual two, A phas e-aliased high first moment data set and a nonaliased low first moment data set are acquired, and the high-moment data are phase unwrapped u sing the low-moment data. The VNR of the resulting measurement is give n by that of the high-moment measurement and increases linearly with t he first moment. A factor of 4 gain in VNR was observed with only a 50 % increase in scan time. Thus, this method is a much more efficient wa y to increase VNR than simple averaging.