Single scan PC-MRI by alternating the velocity encoding gradient polarity between phase encoding steps.

The purpose of this study was to develop a faster approach to phase contrast magnetic resonance imaging. This article proposes a phase contrast imaging scheme called single scan phase contrast in which the polarity of the velocity-encoding gradient is alternated between phase encoding steps. In single scan phase contrast, ghost images due to moving spins form. The signal intensity of the ghost images is modulated by the sine of the motion-induce phase shift. Prior to image acquisition, the region of interest containing moving spins is identified, and the field of view is configured so to avoid overlap between the object in the image and the ghost image(s) due to motion in the region of interest. The image values of the region of interest and the ghost image are used to quantify velocity. At best, single scan phase contrast reduces the total acquisition time by a factor of two when compared to phase contrast. In this study, single scan phase contrast is validated against phase contrast in phantom and in vivo.