Figure 1.

(a) Magnetization evolution after an IR (inversion recovery) preparation in Look-Locker acquisition. With constant RF excitation, magnetization starts from -M and reaches a steady state indicated as Mss. (b) MP-GRASP acquisition scheme. Following each IR preparation, a series of continuous radial stacks are acquired. The acquisition ordering is designed in a way that all the spokes at a given rotation angle, referred to as a radial stack, is acquired before moving to the next rotation angle. A delay is added between different IR preparations to allow for magnetization recovery. The acquisition angle for each radial stack follows the equation shown below, where m indicates the m^th spoke, and n indicates the n^th repetition, and N indicates the total number of repetitions to be acquired. (c) The acquisition of each radial stack can be implemented with a linear reordering scheme (from one edge to the other side) or a center-out reordering scheme (from the center to the periphery).