Multiple Acquisitions with Global Inversion Cycling (MAGIC): A Multislice Technique for Vascular-Space-Occupancy Dependent fMRI

Recently, a new fMRI technique, termed vascular-space-occupancy (VASO), was introduced that uses T₁-based blood nulling to detect cerebral blood volume (CBV) changes during brain activity. However, similar to other T₁-preparation methods, this technique is hampered by the fact that there is only one zero-crossing on the relaxation curve, presently limiting its application to single-slice studies. A multislice VASO-fMRI method is presented that employs a series of nonselective 180° pulses to periodically invert the magnetization and maintain it around zero, while acquiring slices in between. The effects of magnetization transfer and signal contamination by stimulated echoes are discussed. Solutions to reduce the effect of T ₁-signal decay as a function of slice number are provided. Phantom data show excellent agreement between experiments and numerical simulations. Multislice VASO-fMRI images of visual stimulation show effective blood nulling in all slices and appropriate functional activations in all volunteers (n = 4).