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Calibrated BOLD using direct measurement of changes in venous oxygenation

Driver, Ian D.; Hall, Emma L.; Wharton, Samuel J.; Pritchard, Susan E.; Francis, Susan T.; Gowland, Penny A.

Authors

Ian D. Driver

Emma L. Hall

Samuel J. Wharton

Susan E. Pritchard

Susan T. Francis

Penny A. Gowland

Abstract

Calibration of the BOLD signal is potentially of great value in providing a closer measure of the underlying changes in brain function related to neuronal activity than the BOLD signal alone, but current approaches rely on an assumed relationship between cerebral blood volume (CBV) and cerebral blood flow (CBF). This is poorly characterised in humans and does not reflect the predominantly venous nature of BOLD contrast, whilst this relationship may vary across brain regions and depend on the structure of the local vascular bed. This work demonstrates a new approach to BOLD calibration which does not require an assumption about the relationship between cerebral blood volume and cerebral blood flow. This method involves repeating the same stimulus both at normoxia and hyperoxia, using hyperoxic BOLD contrast to estimate the relative changes in venous blood oxygenation and venous CBV. To do this the effect of hyperoxia on venous blood oxygenation has to be calculated, which requires an estimate of basal oxygen extraction fraction, and this can be estimated from the phase as an alternative to using a literature estimate. Additional measurement of the relative change in CBF, combined with the blood oxygenation change can be used to calculate the relative change in CMRO2 due to the stimulus. CMRO2 changes of 18 ± 8% in response to a motor task were measured without requiring the assumption of a CBV/CBF coupling relationship, and are in agreement with previous approaches.

Journal Article Type Article
Publication Date Nov 15, 2012
Journal NeuroImage
Print ISSN 1053-8119
Electronic ISSN 1053-8119
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 63
Issue 3
Institution Citation Driver, I. D., Hall, E. L., Wharton, S. J., Pritchard, S. E., Francis, S. T., & Gowland, P. A. (2012). Calibrated BOLD using direct measurement of changes in venous oxygenation. NeuroImage, 63(3), doi:10.1016/j.neuroimage.2012.08.045
DOI https://doi.org/10.1016/j.neuroimage.2012.08.045
Publisher URL http://www.sciencedirect.com/science/article/pii/S1053811912008531
Copyright Statement Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by/4.0

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