Water Exchange across the Blood-Brain Barrier in Obstructive Sleep Apnea: An MRI Diffusion-Weighted Pseudo-Continuous Arterial Spin Labeling Study.
OBJECTIVE
Obstructive sleep apnea (OSA) subjects show brain injury in sites that control autonomic, cognitive, and mood functions that are deficient in the condition. The processes contributing to injury may include altered blood-brain barrier (BBB) actions. Our aim was to examine BBB function, based on diffusion-weighted pseudo-continuous arterial spin labeling (DW-pCASL) procedures, in OSA compared to controls.


METHODS
We performed DW-pCASL imaging in nine OSA and nine controls on a 3.0-Tesla MRI scanner. Global mean gray and white matter arterial transient time (ATT, an index of large artery integrity), water exchange rate across the BBB (Kw, BBB function), DW-pCASL ratio, and cerebral blood flow (CBF) values were compared between OSA and control subjects.


RESULTS
Global mean gray and white matter ATT (OSA vs. controls; gray matter, 1.691 ± .120 vs. 1.658 ± .109 second, P = .49; white matter, 1.700 ± .115 vs. 1.650 ± .114 second, P = .44), and CBF values (gray matter, 57.4 ± 15.8 vs. 58.2 ± 10.7 ml/100 g/min, P = .67; white matter, 24.2 ± 7.0 vs. 24.6 ± 6.7 ml/100 g/min, P = .91) did not differ significantly, but global gray and white matter Kw (gray matter, 158.0 ± 28.9 vs. 220.8 ± 40.6 min(-1) , P = .002; white matter, 177.5 ± 57.2 vs. 261.1 ± 51.0 min(-1) , P = .006), and DW-pCASL ratio (gray matter, .727 ± .076 vs. .823 ± .069, P = .011; white matter, .722 ± .144 vs. .888 ± .100, P = .004) values were significantly reduced in OSA over controls.


CONCLUSIONS
OSA subjects show compromised BBB function, but intact large artery integrity. The BBB alterations may introduce neural damage contributing to abnormal functions in OSA, and suggest a need to repair BBB function with strategies commonly used in other fields.
Department of Anesthesiology, University of California, Los Angeles, Los Angeles, CA.
Jose A
JA
Palomares
Department of Anesthesiology, University of California, Los Angeles, Los Angeles, CA.
Sudhakar
S
Tummala
Department of Neurology, University of California, Los Angeles, Los Angeles, CA.|Department of Radiological Sciences, University of California, Los Angeles, Los Angeles, CA.
Danny J J
DJ
Wang
Department of Anesthesiology, University of California, Los Angeles, Los Angeles, CA.
Bumhee
B
Park
UCLA School of Nursing, University of California, Los Angeles, Los Angeles, CA.
Mary A
MA
Woo
Department of Medicine, University of California, Los Angeles, Los Angeles, CA.
Daniel W
DW
Kang
Lawson Health Research Institute, London, ON, Canada.
Keith S
KS
St Lawrence
Department of Neurobiology, University of California, Los Angeles, Los Angeles, CA.|Brain Research Institute, University of California, Los Angeles, Los Angeles, CA.
Ronald M
RM
Harper
Department of Anesthesiology, University of California, Los Angeles, Los Angeles, CA.|Department of Radiological Sciences, University of California, Los Angeles, Los Angeles, CA.|Department of Bioengineering, University of California, Los Angeles, Los Angeles, CA.|Brain Research Institute, University of California, Los Angeles, Los Angeles, CA.
Rajesh
R
Kumar
D000328:Adult; D001812:Blood-Brain Barrier / Q000000981:diagnostic imaging* / Q000378:metabolism; D001921:Brain / Q000098:blood supply / Q000000981:diagnostic imaging* / Q000378:metabolism; D002560:Cerebrovascular Circulation / Q000502:physiology*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D066128:Gray Matter / Q000098:blood supply / Q000000981:diagnostic imaging / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D020181:Sleep Apnea, Obstructive / Q000000981:diagnostic imaging* / Q000378:metabolism; D013113:Spin Labels; D014867:Water / Q000378:metabolism*; D066127:White Matter / Q000098:blood supply / Q000000981:diagnostic imaging / Q000378:metabolism
D013113:Spin Labels; D014867:Water
Magnetic resonance imaging; arterial transient time; autonomic control; pseudo-continuous arterial spin labeling