A1 Refereed original research article in a scientific journal
Regional differences in cerebral vascular response to P(a)co(2) changes in humans measured by positron emission tomography
Authors: Ito H, Yokoyama I, Iida H, Kinoshita T, Hatazawa J, Shimosegawa E, Okudera T, Kanno I
Publisher: SAGE PUBLICATIONS INC
Publication year: 2000
Journal: Journal of Cerebral Blood Flow and Metabolism
Journal name in source: JOURNAL OF CEREBRAL BLOOD FLOW AND METABOLISM
Journal acronym: J CEREBR BLOOD F MET
Volume: 20
Issue: 8
First page : 1264
Last page: 1270
Number of pages: 7
ISSN: 0271-678X
DOI: https://doi.org/10.1097/00004647-200008000-00011
Abstract
Hypercapnia and hypocapnia produce cerebral vasodilation and vasoconstriction, respectively. However, regional differences in the vascular response to changes in PaCO2 in the human brain are not pronounced. In the current study, these regional differences were evaluated. In each of the Il healthy subjects, cerebral blood flow (CBF) was measured using O-15-water and positron emission tomography at rest and during hypercapnia and hypocapnia. All CBF images were globally normalized for CBF and transformed into the standard brain anatomy, t values between rest and hypercapnia or hypocapnia conditions were calculated on a pixel-by-pixel basis. In the pens, cerebellum, thalamus, and putamen, significant relative hyperperfusion during hypercapnia was observed, indicating a large capacity for vasodilatation. In the pens and putamen, a significant relative hypoperfusion during hypocapnia, that is, a large capacity for vasoconstriction, was also observed, indicating marked vascular responsiveness. In the temporal, temporo-occipital, and occipital cortices, significant relative hypoperfusion during hypercapnia and significant relative hypoperfusion during hypocapnia were observed, indicating: that cerebral vascular tone at rest might incline toward vasodilatation. Such regional heterogeneity of the cerebral vascular response should be considered in the assessment of cerebral perfusion reserve by hypercapnia and in the correction of CBF measurements for variations in subjects' resting PaCO2.
Hypercapnia and hypocapnia produce cerebral vasodilation and vasoconstriction, respectively. However, regional differences in the vascular response to changes in PaCO2 in the human brain are not pronounced. In the current study, these regional differences were evaluated. In each of the Il healthy subjects, cerebral blood flow (CBF) was measured using O-15-water and positron emission tomography at rest and during hypercapnia and hypocapnia. All CBF images were globally normalized for CBF and transformed into the standard brain anatomy, t values between rest and hypercapnia or hypocapnia conditions were calculated on a pixel-by-pixel basis. In the pens, cerebellum, thalamus, and putamen, significant relative hyperperfusion during hypercapnia was observed, indicating a large capacity for vasodilatation. In the pens and putamen, a significant relative hypoperfusion during hypocapnia, that is, a large capacity for vasoconstriction, was also observed, indicating marked vascular responsiveness. In the temporal, temporo-occipital, and occipital cortices, significant relative hypoperfusion during hypercapnia and significant relative hypoperfusion during hypocapnia were observed, indicating: that cerebral vascular tone at rest might incline toward vasodilatation. Such regional heterogeneity of the cerebral vascular response should be considered in the assessment of cerebral perfusion reserve by hypercapnia and in the correction of CBF measurements for variations in subjects' resting PaCO2.
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