Three‐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 three measurements/flow encoding axis rather than the usual two. A phase‐aliased high first moment data set and a nonaliased low first moment data set are acquired, and the high‐moment data are phase unwrapped using the low‐moment data. The VNR of the resulting measurement is given by that of the high‐moment measurement and increases linearly with the 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 way to increase VNR than simple averaging.