Functional mapping of the human visual cortex at 4 and 1.5 tesla using deoxygenation contrast EPI.
The effects of photic stimulation on the visual cortex of human brain were studied by means of gradient-echo echo-planar imaging (EPI). Whole-body 4 and 1.5 T MRI systems, equipped with a small z axis head gradient coil, were used. Variations of image intensity of up to 28% at 4 T, and up to 7% at 1.5 T, were observed in primary visual cortex, corresponding to an increase of blood oxygenation in regions of increased neural activity. The larger effects at 4 T are due to the increased importance of the susceptibility difference between deoxygenated and oxygenated blood at high fields.
Turner
R
R
Laboratory of Cardiac Energetics, NHLBI, National Institutes of Health, Bethesda, Maryland 20892.
Jezzard
P
P
Wen
H
H
Kwong
K K
KK
Le Bihan
D
D
Zeffiro
T
T
Balaban
R S
RS
D000328:Adult; D002560:Cerebrovascular Circulation / Q000502:physiology; D017352:Echo-Planar Imaging / Q000379:methods*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D010775:Photic Stimulation; D014793:Visual Cortex / Q000033:anatomy & histology*
D010100:Oxygen