title: Cerebrovascular reactivity in the brain white matter: magnitude, temporal characteristics, and age effects.
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.
authors.affiliation: 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.
authors.forename: Binu P
authors.initials: BP
authors.lastname: Thomas
authors.affiliation: 1] Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, Texas, USA [2] Department of Psychiatry, UT Southwestern Medical Center, Dallas, Texas, USA.
authors.forename: Peiying
authors.initials: P
authors.lastname: Liu
authors.affiliation: Center for Vital Longevity, UT Dallas, Dallas, Texas, USA.
authors.forename: Denise C
authors.initials: DC
authors.lastname: Park
authors.affiliation: Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Matthias J P
authors.initials: MJ
authors.lastname: van Osch
authors.affiliation: 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.
authors.forename: Hanzhang
authors.initials: H
authors.lastname: Lu
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D002245:Carbon Dioxide / Q000097:blood; D002540:Cerebral Cortex / Q000098:blood supply / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology; D002560:Cerebrovascular Circulation; D006801:Humans; D018810:Magnetic Resonance Angiography; D008833:Microcirculation; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D011859:Radiography; D014664:Vasodilation
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen