Improved centric phase encoding orders for three-dimensional magnetization-prepared MR angiography.

New centric phase encoding orders are introduced for transient state three-dimensional MR imaging. Unlike previous centric orders, these variants are not fixed with respect to differences in the relative y and z fields of view, but are tailored to account for the, differential degrees of gradient dephasing in the Ky and Kz phase encoding directions and thus maintain the highest weighting for the most central k-space values. The new centric orders are compared with previous methods in both simulation and experimental magnetization-prepared MR angiography of the carotid and renal arteries. In comparison with other tested centric orders, the new methods provided better retention of true vessel shape caused by isotropic blurring across the phase encoding plane. In addition, the new methods provided increased contrast, with the degree of improvement over previous methods depending on vessel orientation, size, and degree of inflow.