scholarly journals Oxygen Extraction Fraction and Stroke Risk in Patients with Carotid Stenosis or Occlusion: A Systematic Review and Meta-Analysis

2013 ◽  
Vol 35 (2) ◽  
pp. 250-255 ◽  
Author(s):  
A. Gupta ◽  
H. Baradaran ◽  
A. D. Schweitzer ◽  
H. Kamel ◽  
A. Pandya ◽  
...  
Keyword(s):  
Systematic Review ◽  
Carotid Stenosis ◽  
Stroke Risk ◽  
Meta Analysis ◽  
Oxygen Extraction Fraction ◽  
Oxygen Extraction ◽  
Extraction Fraction

scholarly journals Hemodynamics and oxygen extraction in chronic large artery steno-occlusive disease: Clinical applications for predicting stroke risk

2017 ◽  
Vol 38 (9) ◽  
pp. 1584-1597 ◽  
Author(s):  
Colin P Derdeyn
Keyword(s):  
Blood Flow ◽  
Ischemic Stroke ◽  
Carotid Artery ◽  
Stroke Risk ◽  
Arterial Stenosis ◽  
Oxygen Extraction Fraction ◽  
Oxygen Extraction ◽  
Large Artery ◽  
Extraction Fraction ◽  
Hemodynamic Assessment

Depending on the adequacy of collateral sources of blood flow, arterial stenosis or occlusion may lead to reduced perfusion pressure and ultimately reduced blood flow in the distal territory supplied by that vessel. There are two well-defined compensatory mechanisms to reduced pressure or flow – autoregulatory vasodilation and increased oxygen extraction fraction. Other changes, such as metabolic downregulation, are likely. The positive identification of autoregulatory vasodilation and increased oxygen extraction fraction in humans is an established risk factor for future ischemic stroke in some disease states such as atherosclerotic carotid stenosis and occlusion. The mechanisms by which ischemic stroke may occur are not clear, and may include an increased vulnerability to embolic events. The use of hemodynamic assessment to identify patients with occlusive vasculopathy at an increased risk for stroke is very appealing for several different patient populations, such as those with symptomatic intracranial atherosclerotic disease, moyamoya phenomenon, complete internal carotid artery occlusion, and asymptomatic cervical carotid artery stenosis. While there is very good data for stroke risk prediction in some of these groups, no intervention based on these tools has been proven effective yet. In this manuscript, we will review these topics above and identify areas for future research.

scholarly journals Cerebellum as the Normal Reference for the Detection of Increased Cerebral Oxygen Extraction

2010 ◽  
Vol 30 (10) ◽  
pp. 1767-1776 ◽  
Author(s):  
Thomas T Jiang ◽  
Tom O Videen ◽  
Robert L Grubb ◽  
William J Powers ◽  
Colin P Derdeyn
Keyword(s):  
Stroke Risk ◽  
Oxygen Extraction Fraction ◽  
Oxygen Extraction ◽  
Reference Region ◽  
Positron Emission Tomographic ◽  
Extraction Fraction ◽  
Kaplan Meier ◽  
Positron Emission ◽  
Hemodynamic Impairment ◽  
A Prospective Study

Hemispheric ratios of oxygen extraction fraction (OEF), a proven methodology for the detection of severe hemodynamic impairment and stroke risk, are not sensitive for detecting bilateral hemispheric increases in OEF. The aim of this study was to investigate the use of cerebellum as the reference normal. We analyzed positron emission tomographic (PET) measurements of count-based OEF and clinical data from 57 patients with unilateral atherosclerotic carotid occlusion and 13 controls enrolled in a prospective study of stroke risk. The ipsilateral, contralateral, and total cerebellum were each evaluated as possible reference regions, and the ratios of the middle cerebral artery (MCA) hemispheric OEF counts against those in each reference region were determined. A statistically significant correlation ( P<0.0001) was observed with all three MCA-to-cerebellar ratios when compared with the gold standard of ipsilateral-to-contralateral MCA hemispheric ratio. Kaplan–Meier analyses showed all MCA-to-cerebellar ratios to be predictive of stroke. By using the total cerebellum method, 7 strokes were found to have occurred in 20 patients with increased OEF ( P=0.0007), compared with 7 strokes out of 16 patients with elevated OEF using the ipsilateral or contralateral cerebellum methods ( P<0.0001). These methods may be useful for categorizing the hemodynamic status of patients with bilateral cerebral occlusive diseases, including atherosclerosis and moyamoya, to determine the association with the risk of subsequent stroke.

scholarly journals Analysis of postprocedural microembolic infarctions and global oxygen extraction fraction during balloon-protected carotid artery stenting: Preliminary study

2021 ◽  
Vol 12 ◽  
pp. 87
Author(s):  
Hidemichi Ito ◽  
Masashi Uchida ◽  
Hiroshi Takasuna ◽  
Ichiro Takumi ◽  
Tanaka Yuichiro
Keyword(s):  
Cerebral Ischemia ◽  
Carotid Artery ◽  
Carotid Stenosis ◽  
Carotid Artery Stenting ◽  
Cerebral Hypoperfusion ◽  
Oxygen Extraction Fraction ◽  
Oxygen Extraction ◽  
Black Blood ◽  
Extraction Fraction ◽  
Carotid Flow

Background: Atherosclerotic carotid stenosis with impaired cerebral perfusion is a risk factor for cerebral ischemia. In major carotid stenoocclusive diseases, increased oxygen extraction fraction (OEF) is associated with ischemic stroke. Balloon-protected carotid artery stenting (CAS) is valuable for high-grade carotid stenosis. However, while balloon-protected CAS can effectively reduce the occurrence of ischemic complications by blocking carotid flow, cerebral hypoperfusion may result in simultaneous cerebral ischemia. We sought to evaluate whether increased OEF during balloon-protected CAS can predict postprocedural microembolic infarction (MI). Methods: Eighty-four patients who underwent balloon-protected CAS were enrolled. Initial, intraprocedural, and postprocedural OEFs were calculated from the cerebral arteriovenous oxygen differences obtained from blood sampled just before the temporary occlusion and reperfusion of the internal carotid artery during and after the procedure. MIs were evaluated by diffusion-weighted imaging (DWI). Patients were classified into two groups based on the presence or absence of new MIs, and the relationship between the OEF and postprocedural MIs was analyzed. Results: New DWI-positive lesions were found in 37 cases (44.0%). Age, signal intensity ratio (SIR) of carotid plaque on T1-weighted black blood magnetic resonance imaging, and intraprocedural OEF were significantly higher in the DWI-positive group. The high SIR and intraprocedural OEF were significantly associated with the development of postprocedural MIs in multivariate analysis. MIs were correlated with the increase in OEF. Conclusion: Increased intraprocedural OEF, obtained by blood sampling during balloon-protected CAS, could predict the incidence of postprocedural MIs. Patients with carotid stenosis could be hemodynamically compromised by carotid flow blockage during balloon-protected CAS.

Abstract TMP93: Elevated Oxygen Extraction Fraction Measured With Noninvasive MRI may be Discriminatory for Stroke Risk in Adults With Sickle Cell Anemia

Stroke ◽  
2016 ◽  
Vol 47 (suppl_1) ◽  
Author(s):  
Lori C Jordan ◽  
Melissa Gindville ◽  
Allison Scott ◽  
Megan K Strother ◽  
Adetola Kassim ◽  
...  
Keyword(s):  
Linear Regression ◽  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Stroke Risk ◽  
Oxygen Extraction Fraction ◽  
Oxygen Extraction ◽  
Extraction Fraction ◽  
Clinical Impairment ◽  
Mean Differences ◽  
Oxygen Carrying Capacity

Introduction: No screening procedures exist for evaluating stroke risk in adults with sickle cell anemia (SCA). Reduced oxygen carrying capacity is present in SCA, which may initially be compensated for by an increase in cerebral blood flow (CBF) and then by increased oxygen extraction fraction (OEF). Hypothesis: OEF and CBF can be measured noninvasively and reproducibly with MRI using clinically-available equipment in adults with SCA; elevated OEF provides added discriminatory capacity for clinical impairment relative to vasculopathy extent and CBF alone. Methods: Structural, CBF-weighted, and MRA imaging, together with a noninvasive OEF-weighted T 2 -relaxation-under-spin-tagging (TRUST)-MRI method was applied in SCA adults (n=26) and race and age-matched controls (n=11). A Kruskal-Wallis test was applied to evaluate mean differences between SCA and control parameters. Linear regression assessed how elevated OEF correlated with increasing clinical impairment defined by presence of infarct, vasculopathy, or use of regular blood transfusions for SCA. Results: OEF had high reproducibility within the same scan session, n=37 (ICC = 0.989). Whole-brain OEF and CBF were increased in SCA adults (OEF=0.46±0.08; CBF=52.4±8.3 ml/100g/min) versus controls (OEF=0.35±0.06; CBF=43.6±5.1 ml/100g/min). Hematocrit and OEF were inversely correlated (R 2 =0.72; p<0.01). Linear regression revealed a stronger relationship of OEF than CBF with clinical impairment. In SCA adults without impairment (n=12) CBF and OEF have an inverse relationship (R 2 =0.41; p=0.01, Fig. 1A) but with clinical impairment (infarct, vasculopathy or severe pain requiring regular transfusions, n=14) CBF and OEF become uncoupled (R 2 =0.08; p=0.16; Fig. 1B) as CBF may not be able to increase further and may plateau or decline. Conclusion: TRUST-MRI OEF is a rapid, reproducible measure. OEF shows promise as screening tool for hemodynamic impairment and stroke risk in adults with SCA.

scholarly journals EXPRESS: Stroke risk following traumatic brain injury: systematic review and meta-analysis

2021 ◽  
pp. 174749302110042
Author(s):  
Grace Mary Turner ◽  
Christel McMullan ◽  
Olalekan Lee Aiyegbusi ◽  
Danai Bem ◽  
Tom Marshall ◽  
...  
Keyword(s):  
Systematic Review ◽  
Stroke Risk ◽  
Meta Analysis ◽  
Vitamin K Antagonists ◽  
Cochrane Library ◽  
Control Group ◽  
Large Sample Size ◽  
Hazard Ratios ◽  
Increased Risk ◽  
The Cochrane Library

Aims To investigate the association between TBI and stroke risk. Summary of review We undertook a systematic review of MEDLINE, EMBASE, CINAHL, and The Cochrane Library from inception to 4th December 2020. We used random-effects meta-analysis to pool hazard ratios (HR) for studies which reported stroke risk post-TBI compared to controls. Searches identified 10,501 records; 58 full texts were assessed for eligibility and 18 met the inclusion criteria. The review included a large sample size of 2,606,379 participants from four countries. Six studies included a non-TBI control group, all found TBI patients had significantly increased risk of stroke compared to controls (pooled HR 1.86; 95% CI 1.46-2.37). Findings suggest stroke risk may be highest in the first four months post-TBI, but remains significant up to five years post-TBI. TBI appears to be associated with increased stroke risk regardless of severity or subtype of TBI. There was some evidence to suggest an association between reduced stroke risk post-TBI and Vitamin K antagonists and statins, but increased stroke risk with certain classes of antidepressants. Conclusion TBI is an independent risk factor for stroke, regardless of TBI severity or type. Post-TBI review and management of risk factors for stroke may be warranted.

scholarly journals Oxygen Extraction Fraction at Maximally Vasodilated Tissue in the Ischemic Brain Estimated from the Regional CO2 Responsiveness Measured by Positron Emission Tomography

1988 ◽  
Vol 8 (2) ◽  
pp. 227-235 ◽  
Author(s):  
Iwao Kanno ◽  
Kazuo Uemura ◽  
Schuichi Higano ◽  
Matsutaro Murakami ◽  
Hidehiro Iida ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Resting State ◽  
Emission Tomography ◽  
Oxygen Extraction Fraction ◽  
Oxygen Extraction ◽  
Cross Point ◽  
Steady State Method ◽  
Extraction Fraction ◽  
Positron Emission ◽  
Vascular Responsiveness

The oxygen extraction fraction (OEF) at maximally vasodilated tissue in patients with chronic cerebrovascular disease was evaluated using positron emission tomography. The vascular responsiveness to changes in PaCO2 was measured by the H215O autoradiographic method. It was correlated with the resting-state OEF, as estimated using the 15O steady-state method. The subjects comprised 15 patients with unilateral or bilateral occlusion and stenosis of the internal carotid artery or middle cerebral artery or moyamoya disease. In hypercapnia, the scattergram between the OEF and the vascular responsiveness to changes in PaCO2 revealed a significant negative correlation in 11 of 19 studies on these patients, and the OEF at the zero cross point of the regression line with a vascular responsiveness of 0 was 0.53 ± 0.08 (n = 11). This OEF in the resting state corresponds to exhaustion of the capacity for vasodilation. The vasodilatory capacity is discussed in relation to the lower limit of autoregulation.

scholarly journals Quantifying the changes in oxygen extraction fraction and cerebral activity caused by caffeine and acetazolamide

2016 ◽  
Vol 37 (3) ◽  
pp. 825-836 ◽  
Author(s):  
Sagar Buch ◽  
Yongquan Ye ◽  
E Mark Haacke
Keyword(s):  
Oxygen Saturation ◽  
A Priori ◽  
Susceptibility Mapping ◽  
Oxygen Extraction Fraction ◽  
Oxygen Extraction ◽  
Cerebral Veins ◽  
Blood Oxygen Saturation ◽  
Vascular Reserve ◽  
Extraction Fraction ◽  
Before And After

A quantitative estimate of cerebral blood oxygen saturation is of critical importance in the investigation of cerebrovascular disease. We aimed to measure the change in venous oxygen saturation (Yv) before and after the intake of the vaso-dynamic agents caffeine and acetazolamide with high spatial resolution using susceptibility mapping. Caffeine and acetazolamide were administered on separate days to five healthy volunteers to measure the change in oxygen extraction fraction. The internal streaking artifacts in the susceptibility maps were reduced by giving an initial susceptibility value uniformly to the structure-of-interest, based on a priori information. Using this technique, Yv for normal physiological conditions, post-caffeine and post-acetazolamide was measured inside the internal cerebral veins as YNormal = 69.1 ± 3.3%, YCaffeine = 60.5 ± 2.8%, and YAcet = 79.1 ± 4.0%. This suggests that susceptibility mapping can serve as a sensitive biomarker for measuring reductions in cerebro-vascular reserve through abnormal vascular response. The percentage change in oxygen extraction fraction for caffeine and acetazolamide were found to be +27.0 ± 3.8% and −32.6 ± 2.1%, respectively. Similarly, the relative changes in cerebral blood flow in the presence of caffeine and acetazolamide were found to be −30.3% and + 31.5%, suggesting that the cerebral metabolic rate of oxygen remains stable between normal and challenged brain states for healthy subjects.

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