High‐resolution, spin‐echo BOLD, and CBF fMRI at 4 and 7 T

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Abstract
With growing interest in noninvasive mapping of columnar organization and other small functional structures in the brain, achieving high spatial resolution and specificity in fMRI is of critical importance. We implemented a simple method for BOLD and perfusion fMRI with high spatial resolution and specificity. Increased spatial resolution was achieved by selectively exciting a slab of interest along the phase‐encoding direction for EPI, resulting in a reduced FOV and number of phase‐encoding steps. Improved spatial specificity was achieved by using SE EPI acquisition at high fields, where it is predominantly sensitive to signal changes in the microvasculature. Robust SE BOLD and perfusion fMRI were obtained with a nominal in‐plane resolution up to 0.5 × 0.5 mm2 at 7 and 4 Tesla, and were highly reproducible under repeated measures. This methodology enables high‐resolution and high‐specificity studies of functional topography in the millimeter to submillimeter spatial scales of the human brain. Magn Reson Med 48:589–593, 2002.