Quantitative study of changes in oxidative metabolism during visual stimulation using absolute relaxation rates

摘要: In the context of quantitative functional MRI (fMRI), deoxyhemoglobin (dHb) content is essential physiological parameter for calibrating blood oxygenation level-dependent (BOLD) signal. studies on humans, baseline dHb or its equivalent has been evaluated indirectly by means carbon dioxide breathing as a reference condition. this study with normal volunteers, mapping was performed in direct manner measuring reversible contribution effective transverse relaxation rate. The BOLD signal change visual cortex during 8 Hz flicker stimulation calibrated based map content. rate that represents stimulation-induced fractional decreased 14% within activated cortex. Simultaneous measurement cerebral flow (CBF) showed an increase 59%. From and CBF changes, metabolic oxygen (CMRO2) calculated to 19–28% ratio CMRO2 2–3:1, which agreed well results similar fMRI humans. method proposed here evaluation may be applicable not only human subjects, but also physiologically altered diseased states, because it requires no perturbation. Copyright © 2005 John Wiley & Sons, Ltd.