Magnetic resonance in medicine : official journal of the Society of Magnetic Resonance in Medicine
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The oxygen extraction fraction of the brain reports on the balance between oxygen delivery and consumption and can be used to assess deviations in physiological homeostasis. This is relevant clinically as well as for calibrating blood oxygen level-dependent functional MRI responses. Oxygen extraction fraction is reflected in the arteriovenous difference in oxygen saturation fraction (Y(v) - Y(a) ), which can be determined from venous T(2) values when arterial oxygenation is known. ⋯ The venous T(2) (for 10 msec Carr-Purcell-Meiboom-Gill interecho time) for normal volunteers was 62.4 ± 6.1 msec (n = 20). A calibration curve relating T(2) to blood oxygenation was established using a blood perfusion phantom. Using this calibration, a whole-brain oxygen extraction fraction of 0.37 ± 0.04 was determined (n = 20), in excellent agreement with literature values.