Analogously to the MAGIC VASO method (Lu et al. 2004) with multiple inversion pulses, the variable flip angle approach is called Multiple Acquisitions with Global Excitation Cycling (MAGEC) VASO. Since MAGEC VASO does not rely on a given inversion time, the readout can be prolonged as much as needed (at the cost of TR). This allows for increased coverage with up to 72–104 slices (and more) at 0.8 mm isotropic resolution and with TR of 6.5 – 8s. See Fig. 1A for a graphical depiction of the MAGEC sequence discussed here. Since the blood z-magnetization is not completely nulled here, the MAGEC approach can contain small CBF-dependent VASO signal amplifications. Since CBF is believed to be dominated from capillary water exchange only, this will not compromise the layer-specificity. It rather improves the sensitivity. As long as there is a reference image acquired without this T1-weighting, the T1-related signal changes can be separated from T2*-related signal changes to ultimately extract CBV signal traces without BOLD contaminations. For further discussions of the MAGEC sequence, see https://layerfmri.page.link/WholeBrain_ISMRM20.
