Separation and quantification of perfusion and BOLD effects by simultaneous acquisition of functional I-0- and T-2*-parameter maps

The nature of the coupling between neuronal activity and the hemodynamic re sponse is the subject of intensive research. As a means to simultaneously m easure parametric changes of T-2(*), initial intensity (I,) and perfusion w ith high temporal resolution, a multi-image EPI technique with slice-select ive inversion recovery (ssIR) for arterial spin labeling was developed and implemented. Comparative measurements with and without the preceding slice- selective inversion pulse were performed. I, and R-2(*) changes induced by primary visual stimulation were separated. For ssIR-multi-image EPI the ave rage change of I, over all 12 subjects was 3.4%, corresponding to a perfusi on change of 40 ml/min/100 g, whereas only minor I, changes were observed w ithout inversion. On average, the R-2(*) of the activated pixels changed by -0.62 sec(-1) without inversion, while a significantly reduced average R-2 (*) change of -0.46 sec(-1) was calculated for ssIR-multi-image EPI due to a decreased BOLD effect contribution of the intravascular compartment. (C) 2001 Wiley-Liss, Inc.