Improved estimation of velocity and flow rate using regularized three-point phase-contrast velocimetry

We improved the three-point phase-contrast method by regularization of MR v elocity data after acquisition of a low velocity-to-noise ratio (VNR) veloc ity image and a high VNR aliased velocity image. The phase unwrapping algor ithm is based on the assumed correlation of the velocity of adjacent flow v oxels on the low VNR and the unaliased high VNR images. We used Fourier enc oding with eight velocity-encoding gradient steps to obtain reference veloc ity images of the aorta from five subjects (274 images) and compared them w ith the phase-contrast and three-point phase-contrast images with and witho ut regularization. The VNR of the regularized velocity image was improved b y 9.1 dB and the VNR of the three-point phase-contrast velocity image was i mproved by 0.7 dB with respect to the low first moment velocity image. Corr esponding improvements of 9 dB and 3.7 dB were obtained for the estimations of instantaneous flow rate. (C) 2000 Wiley-Liss, Inc.