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.
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Richard M. Lucas Center for Magnetic Resonance Spectroscopy and Imaging, Department of Radiology, Stanford University, CA 94305-5488.
Pike
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Pelc
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D002555:Cerebrospinal Fluid / Q000502:physiology; D002560:Cerebrovascular Circulation / Q000502:physiology; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008955:Models, Cardiovascular; D008961:Models, Structural; D012212:Rheology