VS saturation pulse sequence with refocusing and tailoring (a), simulated longitudinal magnetization Mz over the v-f plane (b) and for off-resonance f = 0, ±40, ±80 Hz (c, d). A time delay Td (denoted by grey bars) and profile shifting along the velocity axis Δv were iteratively found that maximize the fidelity of an Mz profile in a velocity region ([−3, +50] cm/s) and an off-resonance range ([−80, +80] Hz) expected in the lower extremities. The resulting Mz profiles show that off-resonance immunity is further improved in the prescribed velocity region of interest compared to the VS sequence without tailoring particularly when off-resonance is large.