Effects of refocusing flip angle modulation and view ordering in 3D fast spin echo

Recent advances have reduced scan time in three‐dimensional fast spin echo (3D‐FSE) imaging, including very long echo trains through refocusing flip angle (FA) modulation and 2D‐accelerated parallel imaging. This work describes a method to modulate refocusing FAs that produces sharp point spread functions (PSFs) from very long echo trains while exercising direct control over minimum, center‐k‐space, and maximum FAs in order to accommodate the presence of flow and motion, SNR requirements, and RF power limits. Additionally, a new method for ordering views to map signal modulation from the echo train into k_y‐k_z space that enables nonrectangular k‐space grids and autocalibrating 2D‐accelerated parallel imaging is presented. With long echo trains and fewer echoes required to encode large matrices, large volumes with high in‐ and through‐plane resolution matrices may be acquired with scan times of 3–6 min, as demonstrated for volumetric brain, knee, and kidney imaging. Magn Reson Med 60:640–649, 2008. © 2008 Wiley‐Liss, Inc.