Multislice interleaved excitation cycles (MUSIC): an efficient gradient-echo technique for functional MRI.

A method providing improved slice efficiency for gradient-echo imaging requiring long echo times, such as in functional neuromagnetic resonance imaging, is presented. To enhance the volume coverage while maintaining the short imaging time of a conventional single-slice gradient-echo technique, an interleaved multislice excitation is performed during the echo time. This technique allows detection of susceptibility changes, e.g., the acquisition of stimulated human cortical activation maps, on clinical MR instruments at multiple planes within total imaging times of a few seconds. The efficiency of the technique is demonstrated in the detection of temporary changes in T2* in functional MRI experiments of the human visual cortex at magnetic field strengths of 2 Tesla and 3 Tesla. Fourteen 128 x 128 slices can be acquired in 13 s to cover a large volume-of-interest in the same time that would be required for single-slice acquisition using the conventional technique.