Functional imaging by I0- and T2*-parameter mapping using multi-image EPI

A new functional imaging method has been developed and used to measure T-2*- and initial intensity (I-O)-parameter maps of multiple slices during activation of the cortex with high temporal resolution. Multiple echo-planar images (EPIs) are read out after a single excitation of the spin system, leading to several images with increasing effective echo times. Changes induced by primary visual stimulation in T-2* and I-O were measured in eight subjects. Although stimulation-induced increases in I-O only occurred at short repetition times, T-2* increased from 57.3 to 60.9 ms on average. The method combines the high stability of a single shot EPI experiment with the high information content of a multiecho acquisition. In addition, stimulation-induced changes in inflow can be easily separated from true blood oxygenation level dependent (BOLD) signal changes.