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 degrees 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 T1-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).
Lu
Hanzhang
H
Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
van Zijl
Peter C M
PC
Hendrikse
Jeroen
J
Golay
Xavier
X
D001810:Blood Volume; D001931:Brain Mapping; D002560:Cerebrovascular Circulation; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019047:Phantoms, Imaging; D010775:Photic Stimulation