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J Cereb Blood Flow Metab. 2018 Sep;38(9):1618-1630. doi: 10.1177/0271678X16682509. Epub 2016 Dec 28.

Hemodynamic mechanisms underlying elevated oxygen extraction fraction (OEF) in moyamoya and sickle cell anemia patients.

Author information

1
1 Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, USA.
2
2 Department of Pediatrics, Division of Pediatric Neurology, Vanderbilt University Medical Center, Nashville, USA.
3
3 Vanderbilt Memory & Alzheimer's Center, Vanderbilt University Medical Center, Nashville, USA.
4
4 Department of Neurology, Vanderbilt University Medical Center, Nashville, USA.
5
5 Department of Psychiatry, Vanderbilt University Medical Center, Nashville, USA.

Abstract

Moyamoya is a bilateral, complex cerebrovascular condition characterized by progressive non-atherosclerotic intracranial stenosis and collateral vessel formation. Moyamoya treatment focuses on restoring cerebral blood flow (CBF) through surgical revascularization, however stratifying patients for revascularization requires abilities to quantify how well parenchyma is compensating for arterial steno-occlusion. Globally elevated oxygen extraction fraction (OEF) secondary to CBF reduction may serve as a biomarker for tissue health in moyamoya patients, as suggested in patients with sickle cell anemia (SCA) and reduced oxygen carrying capacity. Here, OEF was measured (TRUST-MRI) to test the hypothesis that OEF is globally elevated in patients with moyamoya (n = 18) and SCA (n = 18) relative to age-matched controls (n = 43). Mechanisms underlying the hypothesized OEF increases were evaluated by performing sequential CBF-weighted, cerebrovascular reactivity (CVR)-weighted, and structural MRI. Patients were stratified by treatment and non-parametric tests applied to compare study variables (significance: two-sided P < 0.05). OEF was significantly elevated in moyamoya participants (interquartile range = 0.38-0.45) compared to controls (interquartile range = 0.29-0.38), similar to participants with SCA (interquartile range = 0.37-0.45). CBF was inversely correlated with OEF in moyamoya participants. Elevated OEF was only weakly related to reductions in CVR, consistent with basal CBF level, rather than vascular reserve capacity, being most closely associated with OEF.

KEYWORDS:

MRI; Oxygen extraction fraction; moyamoya; neurophysiology; stroke

PMID:
28029271
PMCID:
PMC6125968
[Available on 2019-09-01]
DOI:
10.1177/0271678X16682509

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