Comparison of simultaneously measured perfusion and BOLD signal increases during brain activation with T-1-based tissue identification

Perfusion and blood oxygenation level-dependent (BOLD) signals were simulta neously measured during a finger-tapping task at 3T using QUIPSS II with th in-slice TI1 periodic saturation, a modified pulsed arterial spin labeling technique that provides quantitative measurement of perfusion. Perfusion an d BOLD signal changes due to motor activation were obtained and correlated with the T-1 values estimated from echo-planar imaging (EPI)-based T-1 maps on a voxel-by-voxel basis. The peak perfusion signal occurs in voxels with a T-1 of brain parenchyma while the peak BOLD signal occurs in voxels with a T-1 characteristic of blood and cerebrospinal fluid. The locations of th e peak signals of functional BOLD and perfusion only partially overlap on t he order of 40%, Perfusion activation maps will likely represent the sites of neuronal activity better than do BOLD activation maps. (C) 2000 Wiley-Li ss, inc.