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J Cereb Blood Flow Metab. 2014 Feb;34(2):242-7. doi: 10.1038/jcbfm.2013.194. Epub 2013 Nov 6.

Cerebrovascular reactivity in the brain white matter: magnitude, temporal characteristics, and age effects.

Author information

1
1] Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, Texas, USA [2] Biomedical Engineering Graduate Program, UT Southwestern Medical Center, Dallas, Texas, USA [3] Department of Bioengineering, UT Arlington, Arlington, Texas, USA.
2
1] Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, Texas, USA [2] Department of Psychiatry, UT Southwestern Medical Center, Dallas, Texas, USA.
3
Center for Vital Longevity, UT Dallas, Dallas, Texas, USA.
4
Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands.
5
1] Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, Texas, USA [2] Biomedical Engineering Graduate Program, UT Southwestern Medical Center, Dallas, Texas, USA [3] Department of Bioengineering, UT Arlington, Arlington, Texas, USA [4] Department of Psychiatry, UT Southwestern Medical Center, Dallas, Texas, USA.

Abstract

White matter (WM) comprises about half of the brain and its dysfunction is implicated in many brain disorders. While structural properties in healthy and diseased WM have been extensively studied, relatively little is known about the physiology underlying these structural characteristics. Recent advances in magnetic resonance (MR) technologies provided new opportunities to better understand perfusion and microvasculature in the WM. Here, we aim to evaluate vasodilatory capacity of the WM vasculature, which is thought to be important in tissue ischemia and autoregulation. Fifteen younger and fifteen older subjects performed a CO2 inhalation task while blood-oxygenation-level-dependent (BOLD) magnetic resonance imaging (MRI) images were continuously collected. The cerebrovascular reactivity (CVR) index showed that the value of CVR in the WM (0.03±0.002%/mm Hg) was positive, but was significantly lower than that in the gray matter (GM) (0.22±0.01%/mm Hg). More strikingly, the WM response showed a temporal delay of 19±3 seconds compared with GM, which was attributed to the longer time it takes for extravascular CO2 to change. With age, WM CVR response becomes greater and faster, which is opposite to the changes seen in the GM. These data suggest that characteristics of WM CVR are different from that of GM and caution should be used when interpreting pathologic WM CVR results.

PMID:
24192640
PMCID:
PMC3915204
DOI:
10.1038/jcbfm.2013.194
[Indexed for MEDLINE]
Free PMC Article

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