Figure 1.

(a) Sequence diagram of 3D DP-pCASL. (b) Diffusion preparation module: Non-selective pulses were used to compensate for field inhomogeneity, timing of gradients was optimized to minimize eddy current. De-phasing gradient was added along y-axis (4π dephasing per voxel) before tip-up to eliminate phase sensitivity of GRASE readout. Strong spoiler along three axes were added after tip-up to remove residual transverse magnetization. A pair of re-phasing and de-phasing gradients were added at both sides of EPI readout. (c) GRASE readout: Non-selective excitation was used to improve slab profile, re-phasing and rewound de-phasing gradients were added at two sides of EPI readout to maintain MG condition.