Microvascular Functional MR Angiography with Ultra-high-Field 7 T MRI: Comparison with BOLD fMRI

摘要

Microvascular functional MR angiography using ultra-high-field 7 T MRI was used to visualize specific arterial changes in response to stimulation, and the results were compared to conventional blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI). To demonstrate the potential of this new method, we conducted a visual experiment with 14 healthy subjects using optimized acquisition parameters and a dedicated radio frequency coil for 7 T MRI. The signal intensity change in the blood vessels supplying to the visual cortex, specifically the calcarine arteries, was clearly observed during stimulation. The signal changes were increased gradually up to as high as 12% as the vessel segments approach to the visual cortex where neuronal activity was believed to be occurred. The activation foci were not identical to those obtained by conventional fMRI, as expected, but they were closely related and confined to the visual cortical areas, when compared to fMRI responses. Therefore, fMRA technique using ultra-high-field 7 T MRI could provide the direct observation of microvascular changes in the arterial input vessels in relation to neuronal activity.