IMPROVED CENTRIC PHASE-ENCODING ORDERS FOR 3-DIMENSIONAL MAGNETIZATION-PREPARED MR-ANGIOGRAPHY

New centric phase encoding orders are introduced for transient state t hree-dimensional MR imaging. Unlike previous centric orders, these var iants are not fixed with respect to differences in the relative y and z fields of view, but are tailored to account for the differential deg rees of gradient dephasing in the k(y) and k(z) phase encoding directi ons and thus maintain the highest weighting for the most central k-spa ce values. The new centric orders are compared with previous methods i n both simulation and experimental magnetization-prepared MR angiograp hy of the carotid and renal arteries. In comparison with other tested centric orders, the new methods provided better retention of true vess el shape caused by isotropic blurring across the phase encoding plane. In addition, the new methods provided increased contrast, with the de gree of improvement over previous methods depending on vessel orientat ion, size, and degree of inflow.