scholarly journals Response of Inner Retinal Oxygen Extraction Fraction to Light Flicker Under Normoxia and Hypoxia in Rat

2014 ◽  
Vol 55 (9) ◽  
pp. 6055 ◽  
Author(s):  
Pang-yu Teng ◽  
Justin Wanek ◽  
Norman P. Blair ◽  
Mahnaz Shahidi
Keyword(s):  
Oxygen Extraction Fraction ◽  
Oxygen Extraction ◽  
Extraction Fraction ◽  
Light Flicker

scholarly journals The Effects of Diabetic Retinopathy Stage and Light Flicker on Inner Retinal Oxygen Extraction Fraction

2016 ◽  
Vol 57 (13) ◽  
pp. 5586 ◽  
Author(s):  
Anthony E. Felder ◽  
Justin Wanek ◽  
Norman P. Blair ◽  
Charlotte E. Joslin ◽  
Katherine C. Brewer ◽  
...  
Keyword(s):  
Diabetic Retinopathy ◽  
Oxygen Extraction Fraction ◽  
Oxygen Extraction ◽  
Extraction Fraction ◽  
Light Flicker

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.

Abstract W P115: Utilization of Blood Sampling Global Oxygen Extraction Fraction and SPECT to Anticipate Cerebral Hyperperfusion Syndrome Following Elective Carotid Artery Stenting

Stroke ◽  
2015 ◽  
Vol 46 (suppl_1) ◽  
Author(s):  
Takahisa Mori ◽  
Tomonori Iwata ◽  
Yuhei Tanno ◽  
Shigen Kasakura ◽  
Yoshinori Aoyagi ◽  
...  
Keyword(s):  
Carotid Artery ◽  
Carotid Artery Stenting ◽  
Blood Sampling ◽  
Oxygen Extraction Fraction ◽  
Oxygen Extraction ◽  
Cerebral Hyperperfusion Syndrome ◽  
Hyperperfusion Syndrome ◽  
Cerebral Hyperperfusion ◽  
Arterial Blood ◽  
Extraction Fraction

Background: It is required to anticipate cerebral hyperperfusion syndrome (CHS) following carotid artery stenting (CAS). Purpose: The purpose of our retrospective study was to investigate whether or not blood sampling oxygen extraction fraction (OEF) and post-CAS CBF increase in SPECT had relation to CHS following CAS. Methods: Included in our analysis were patients (1) who underwent elective CAS in our institution between October 2010 and May 2014, and (2) who underwent blood sampling for OEF calculation before and immediately after CAS, and (3) who underwent SPECT before and just after CAS. OEF was calculated from cerebral arteriovenous oxygen difference. Arterial blood was sampled from the common carotid artery and venous blood from the dominant-sided superior jugular bulb. CHS was defined as pulsatile headaches, restlessness, convulsion, and/or new neurological symptoms not due to cerebral ischemia within seven days following CAS. CBF was measured before and just after CAS. CBF increase in the CAS side was defined as follows; (post-CAS CBF ratio - pre-CAS CBF ratio) of more than 10%, where CBF ratio was defined as CAS-sided fronto-parietal CBF divided by ipsilateral cerebellar CBF (%). Evaluated were baseline features in patients, pre-CAS OEF, post-CAS OEF, CBF ratio, CBF increase and CHS. Results: During the study period, 134 patients matched our criteria for analysis. Pre-CAS OEF was 0.41+-0.06, post-CAS OEF was 0.42+-0.08, pre-CAS CBF ratio: 88.7+-15.4%, CBF increase: 1.86+-12.3%. Nine patients presented CHS. Among them, pre-CAS OEF, CBF ratio and CBF increase were significant. ROC curves showed that pre-CAS OEF of 0.46 (p<0.001, OR: 9.3), CBF ratio of 92%(p<0.05, OR: 6.5), CBF increase of 8.8% (p<0.005, OR: 6.6) were cut-off values. Among 10 patients with pre-CAS OEF of more than 0.46 and CBF increase of more than 8.8%, 4 patients presented CHS (p<0.0001, OR;15.9). Conclusion: Elevation of pre-CAS OEF and increase of post-CAS CBF were strongly related to CHS.

Oxygen extraction fraction mapping at 3 Tesla using an artificial neural network: A feasibility study

2017 ◽  
Vol 79 (2) ◽  
pp. 890-899 ◽  
Author(s):  
Sebastian Domsch ◽  
Bettina Mürle ◽  
Sebastian Weingärtner ◽  
Jascha Zapp ◽  
Frederik Wenz ◽  
...  
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Feasibility Study ◽  
3 Tesla ◽  
Oxygen Extraction Fraction ◽  
Oxygen Extraction ◽  
Extraction Fraction ◽  
Artificial Neural
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