Retinotopic mapping in the human visual cortex using vascular space occupancy-dependent functional magnetic resonance imaging.

Recently, we introduced a new methodology, vascular space occupancy functional magnetic resonance imaging, which detects brain activation on the basis of blood volume changes in parenchymal microvasculature and may provide higher spatial specificity than the blood oxygenation level-dependent method. To study whether this technique can be used for advanced brain mapping applications, we performed retinotopic mapping using alternating horizontal and vertical wedges that stimulate different portions of the visual field. The results using vascular space occupancy functional magnetic resonance imaging showed clear boundaries for V1/V2/VP/V4v in the ventral areas and V1/V2/V3/V3A in the dorsal areas, similar to the maps obtained using blood oxygenation level-dependent functional magnetic resonance imaging. Vascular space occupancy functional magnetic resonance imaging is a useful addition to the other neuroimaging techniques. Disadvantages of vascular space occupancy functional magnetic resonance imaging include lower contrast-to-noise ratio (about 1/3 of that of blood oxygenation level-dependent method) and limited volume coverage (nine slices for TR=3 s).