Spatial dependence of CBV-fMRI: a comparison between VASO and contrast agent based methods.

In functional magnetic resonance imaging (fMRI), the cerebral blood volume (CBV) based approach with exogenous contrast agent has been found to have better spatial specificity than the widely applied blood oxygenation level-dependent (BOLD) method. Recently, an endogenous CBV-based contrast, vascular space occupancy-dependent (VASO) technique, was developed for human research. However, the spatial specificity of VASO functional maps is still unclear. In this report, VASO-weighted high-resolution functional map was obtained at 9.4 T. Its spatial dependence across cortical layers was compared to the traditional CBV-weighted fMRI map obtained using contrast agent injection. Both functional maps show good localization at the middle cortical layer.