Evidence for a vascular contribution to diffusion FMRI at high b value

Miller, K. L., Bulte, D. P., Devlin, H., Robson, M. D., Wise, Richard Geoffrey ORCID: https://orcid.org/0000-0003-1700-2144, Woolrich, M. W., Jezzard, P. and Behrens, T. E. J. 2007. Evidence for a vascular contribution to diffusion FMRI at high b value. Proceedings of the National Academy of Sciences of the United States of America 104 (52) , pp. 20967-20972. 10.1073/pnas.0707257105

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Abstract

Recent work has suggested that diffusion-weighted functional magnetic resonance imaging (FMRI) with strong diffusion weighting (high b value) detects neuronal swelling that is directly related to neuronal firing. This would constitute a much more direct measure of brain activity than current methods and represent a major advance in neuroimaging. However, it has not been firmly established that the observed signal changes do not reflect residual vascular effects, which are known to exist at low b value. This study measures the vascular component of diffusion FMRI directly by using hypercapnia, which induces blood flow changes in the absence of a change in neuronal firing. Hypercapnia elicits a similar diffusion FMRI response to a visual stimulus including a rise in percent signal change with increasing b value, which was reported for visual activation. Analysis of the response timing found no evidence for an early response at high b value, which has been reported as evidence for a nonhemodynamic response. These results suggest that a large component of the diffusion FMRI signal at high b value is vascular rather than neuronal.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Psychology Neuroscience and Mental Health Research Institute (NMHRI)
Subjects:	R Medicine > RC Internal medicine > RC0321 Neuroscience. Biological psychiatry. Neuropsychiatry
Uncontrolled Keywords:	brain activation; diffusion MRI; functional MRI; neuronal swelling
Publisher:	National Academy of Sciences
ISSN:	0027-8424
Last Modified:	20 Oct 2022 07:51
URI:	https://orca.cardiff.ac.uk/id/eprint/26638

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