1McConnell
Brain Imaging Centre, Montreal Neurological Institute, McGill University,
Montral, Qubec, Canada; 2IUGM/Universit de Montral, Montral,
Qubec, Canada
In a recently published theoretical model it was predicted that paramagnetic oxygen dissolved in blood significantly contributes to a magnetic susceptibility difference between arterial blood and the surrounding tissue when its concentration in blood ishigh, such as during hyperoxia-based BOLD calibration. We present here a revised model and have re-examined the effect of dissolved oxygen on the blood-tissue susceptibility difference using our alternative formulation and compared it with published experimental data. We found a negligible change of the arterial blood-tissue susceptibility difference between hyperoxia and normoxia, resulting in signal contrast in veins and capillaries only.