Fig. 1.

Demonstration of the proposed off-resonance correction method applied to one VEPCASL cycle. a: A group of four vessels and b: a simulated field map within the labeling plane, shown as the phase accrued during one RF interval due to off-resonance. c: In this example, the desired encoding aims to label the RICA and RVA whilst leaving the LICA and LVA in the control condition, but the combination of the prescribed transverse gradient blip with the phase accrual due to B₀ inhomogeneities leads to a distorted and shifted encoding function, resulting in inefficient labeling. d: If the phase offsets are incorporated into the OES scheme the desired encoding is restored. Contours of zero and π phase between RF pulses, corresponding to the centre of the label (tag) and control regions, are shown with purple and orange dashed lines, respectively.