scholarly journals Tomographic Mapping of Brain Intracellular pH and Extracellular Water Space in Stroke Patients

1985 ◽  
Vol 5 (3) ◽  
pp. 358-368 ◽  
Author(s):  
A. Syrota ◽  
Y. Samson ◽  
C. Boullais ◽  
P. Wajnberg ◽  
C. Loc'h ◽  
...  
Keyword(s):  
Intracellular Ph ◽  
Aerobic Glycolysis ◽  
Oxygen Metabolism ◽  
Oxygen Extraction Fraction ◽  
Oxygen Extraction ◽  
Extracellular Water ◽  
Metabolic Demand ◽  
Phagocytic Cells ◽  
Infarcted Area ◽  
Positron Emission

Functional images of regional intracellular pH (pHi) and of fractional volume of extracellular water (FVECW) were obtained in 10 patients with recent hemispheric infarction (between 10 and 19 days after onset of symptoms) using positron emission tomography (PET). The volume of extracellular water relative to that of total water was evaluated in each pixel of the PET scan 7–8 h after injection of 76Br. The pHi image was calculated from the data obtained after injection of [11C]5,5-dimethyl-2,4-oxazolidinedione and from the FVECW image. Regional CBF, oxygen extraction, and oxygen metabolism were also measured in the same patients. In normal hemisphere, mean ± SD values for FVECW and pHi were 0.12 ± 0.01 and 6.86 ± 0.11, respectively. FVECW was increased in the infarcted area in most patients. pHi was increased in the infarct in seven patients and unchanged in three. The increase in pHi was not correlated with changes in FVECW, CBF, or CMRO2, but there was a significant correlation with the decrease in oxygen extraction fraction in the same region. Thus, the decreased H+ content in the infarcted area was correlated with the occurrence of perfusion in excess of metabolic demand. An alkaline shift in pHi enhances the glycolysis rate and could explain why the glucose metabolism is less affected than the oxygen metabolism in recent cerebral infarction. The pHi measured in the infarct could represent mainly the pHi of phagocytic cells that use aerobic glycolysis to synthesize hydrogen peroxide.

scholarly journals Measurement of End-Capillary Po2 with Positron Emission Tomography

1988 ◽  
Vol 8 (3) ◽  
pp. 403-410 ◽  
Author(s):  
N. M. Alpert ◽  
R. B. Buxton ◽  
J. A. Correia ◽  
R. M. Katz ◽  
R. H. Ackerman
Keyword(s):  
Positron Emission Tomography ◽  
Oxygen Saturation ◽  
Normal Subjects ◽  
Oxygen Metabolism ◽  
Emission Tomography ◽  
Oxygen Extraction Fraction ◽  
Oxygen Extraction ◽  
Protein Levels ◽  
Extraction Fraction ◽  
Positron Emission

The analysis of positron emission tomography measurements of oxygen metabolism has been extended to provide a quantitative estimate of end-capillary Po2. The principle of this extension rests on the idea that the oxygen extraction fraction can be used to calculate the end-capillary oxygen saturation of the blood. The relation between oxygen saturation and Po2 is obtained through the oxygen dissociation curve. Our studies show that in addition to the local oxygen extraction fraction, arterial Po2 and pH values are needed in the calculation, whereas fairly large variations in factors such as Pco2, hematocrit, hemoglobin, and plasma protein levels have little or no effect. Rough estimates of end-capillary Po2 can be made using standard o2 dissociation nomograms. Blood gas and acid-base properties of blood have been known for decades, making it possible to account accurately for individual differences that may be encountered when studying patients. Measurements in nine normal subjects yielded a mean end-capillary Po2 value of 31.2 mm Hg. The ability to make a quantitative visualization of altered patterns of end-capillary Po2 provides an additional dimension to the investigation of stroke disease and tumor metabolism.

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.

Reversal of Focal Misery Perfusion after Intracranial Angioplasty: Case Report

Neurosurgery ◽  
2001 ◽  
Vol 48 (2) ◽  
pp. 436-440 ◽  
Author(s):  
Colin P. Derdeyn ◽  
DeWitte T. Cross ◽  
Christopher J. Moran ◽  
Ralph G. Dacey
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Carotid Artery ◽  
Intracranial Stenosis ◽  
Oxygen Extraction Fraction ◽  
Oxygen Extraction ◽  
Positron Emission ◽  
Misery Perfusion ◽  
Before And After ◽  
Hemodynamic Measurements

Abstract OBJECTIVE AND IMPORTANCE The presence of reduced blood flow and increased oxygen extraction fraction (OEF) (misery perfusion) in the hemisphere distal to an occluded carotid artery is a proven risk factor for subsequent stroke. Whether angioplasty of intracranial stenosis is sufficient to reverse this condition has not been documented. CLINICAL PRESENTATION A 67-year-old man exhibited progressive right hemispheric ischemic symptoms despite maximal antiplatelet and antithrombotic therapy. Angiography demonstrated focal 80% stenosis of the supraclinoid segment of the ipsilateral internal carotid artery. TECHNIQUE 15O positron emission tomographic measurements of cerebral blood flow and OEF were made before and after transfemoral percutaneous angioplasty. OEF values measured before angioplasty were elevated in the middle cerebral artery distal to the stenosis. Angioplasty reduced the degree of luminal stenosis to 40% (linear diameter). OEF values measured 36 hours after angioplasty were normal. CONCLUSION Angioplasty of intracranial stenosis can restore normal cerebral blood flow and oxygen extraction, despite mild residual stenosis after the procedure. Hemodynamic measurements may be useful for the identification of patients with the greatest potential to benefit from angioplasty.

Validation of T 2 ‐based oxygen extraction fraction measurement with 15 O positron emission tomography

2020 ◽  
Vol 85 (1) ◽  
pp. 290-297
Author(s):  
Dengrong Jiang ◽  
Shengwen Deng ◽  
Crystal G. Franklin ◽  
Michael O'Boyle ◽  
Wei Zhang ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Emission Tomography ◽  
Oxygen Extraction Fraction ◽  
Oxygen Extraction ◽  
Extraction Fraction ◽  
Positron Emission ◽  
Fraction Measurement

Abstract TMP38: Diminished Cortical Thickness and Increased Oxygen Extraction Fraction in Moyamoya Disease

Stroke ◽  
2013 ◽  
Vol 44 (suppl_1) ◽  
Author(s):  
John Lee ◽  
James Sagar ◽  
Gregory Zipfel ◽  
Allyson Zazulia ◽  
Colin Derdeyn
Keyword(s):  
Cortical Thickness ◽  
Cortical Neurons ◽  
Oxygen Extraction Fraction ◽  
Oxygen Extraction ◽  
Down Regulation ◽  
Extraction Fraction ◽  
Positron Emission ◽  
Hemodynamic Impairment ◽  
Revascularization Surgery ◽  
Moyamoya Phenomenon

PURPOSE: Chronic hemodynamic impairment may lead to reduced cortical thickness, perhaps related to metabolic down-regulation in cortical neurons. The purpose of this study was to determine whether hemodynamic impairment correlated with diminished cortical thickness in patients with idiopathic moyamoya phenomenon. METHODS: The study was a retrospective analysis of a prospective, blindly-adjudicated, multicenter patient cohort. Inclusion criteria required moyamoya phenomenon diagnosed by catheter angiography and presumed idiopathic basal arterial occlusive disease. Oxygen extraction fraction (OEF) was measured using positron emission tomography (PET). Hemodynamic impairment was determined by comparing the OEF of middle cerebral artery territories to cerebellar regions and to normal control subjects. MR imaging was obtained concurrently with PET, within several hours, and cortical thickness estimates were made with Freesurfer (http://surfer.nmr.mgh.harvard.edu). OEF measurements were then compared to cortical thickness measurements. RESULTS: Adequate MR studies were available for 40 subjects. Mean age was 44 years. Eleven were male. Thirty-one had bilateral disease. Three had increased OEF in both hemispheres and four had unilateral increased OEF. Three patients underwent revascularization surgery during follow-up. Robust linear regression of relative cortical thickness to relative OEF is shown below: the slope was -0.02693 (-0.03002, -0.02384), the intercept was 1.022 (1.019, 1.025) at 95% confidence. Pearson’s R-square was 0.9648. CONCLUSIONS: Chronic hemodynamic impairment may be associated with reduced cortical thickness. This may reflect reversible down-regulation or irreversible subclinical ischemic injury. Supported by NINDS RO1 NS051631, 1 UL1 RR024992-01, 1 TL1 RR024995-01 and 1 KL2 RR 024994-01 from the National Center for Research Resources (NCRR).

Enhanced oxygen extraction and reduced flow heterogeneity in exercising muscle in endurance-trained men

2001 ◽  
Vol 280 (6) ◽  
pp. E1015-E1021 ◽  
Author(s):  
Kari K. Kalliokoski ◽  
Vesa Oikonen ◽  
Teemu O. Takala ◽  
Hannu Sipilä ◽  
Juhani Knuuti ◽  
...  
Keyword(s):  
Transit Time ◽  
Isometric Exercise ◽  
Oxygen Extraction Fraction ◽  
Oxygen Extraction ◽  
Relative Dispersion ◽  
Trained Subjects ◽  
Flow Heterogeneity ◽  
Positron Emission ◽  
Exercise Efficiency ◽  
Femoris Muscle

The aim of this study was to investigate the effects of endurance training on skeletal muscle hemodynamics and oxygen consumption. Seven healthy endurance-trained and seven untrained subjects were studied. Oxygen uptake, blood flow, and blood volume were measured in the quadriceps femoris muscle group by use of positron emission tomography and [15O]O2, [15O]H2O, and [15O]CO during rest and one-legged submaximal intermittent isometric exercise. The oxygen extraction fraction was higher (0.49 ± 0.14 vs. 0.29 ± 0.12; P = 0.017) and blood transit time longer (0.6 ± 0.1 vs. 0.4 ± 0.1 min; P = 0.04) in the exercising muscle of the trained compared with the untrained subjects. The flow heterogeneity by means of relative dispersion was lower for the exercising muscle in the trained (50 ± 9%) compared with the untrained subjects (65 ± 13%, P = 0.025). In conclusion, oxygen extraction is higher, blood transit time longer, and perfusion more homogeneous in endurance-trained subjects compared with untrained subjects at the same workload. These changes may be associated with improved exercise efficiency in the endurance-trained subjects.

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 More homogeneous capillary flow and oxygenation in deeper cortical layers correlate with increased oxygen extraction

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Baoqiang Li ◽  
Tatiana V Esipova ◽  
Ikbal Sencan ◽  
Kıvılcım Kılıç ◽  
Buyin Fu ◽  
...  
Keyword(s):  
Oxygen Delivery ◽  
Barrel Cortex ◽  
Capillary Flow ◽  
Oxygen Demand ◽  
Oxygen Extraction Fraction ◽  
Oxygen Extraction ◽  
Homogeneous Distribution ◽  
Metabolic Demand ◽  
Cortical Layers ◽  
Network Adaptation

Our understanding of how capillary blood flow and oxygen distribute across cortical layers to meet the local metabolic demand is incomplete. We addressed this question by using two-photon imaging of resting-state microvascular oxygen partial pressure (PO2) and flow in the whisker barrel cortex in awake mice. Our measurements in layers I-V show that the capillary red-blood-cell flux and oxygenation heterogeneity, and the intracapillary resistance to oxygen delivery, all decrease with depth, reaching a minimum around layer IV, while the depth-dependent oxygen extraction fraction is increased in layer IV, where oxygen demand is presumably the highest. Our findings suggest that more homogeneous distribution of the physiological observables relevant to oxygen transport to tissue is an important part of the microvascular network adaptation to local brain metabolism. These results will inform the biophysical models of layer-specific cerebral oxygen delivery and consumption and improve our understanding of the diseases that affect cerebral microcirculation.

scholarly journals Defining Ischemic Burden after Traumatic Brain Injury Using 15O PET Imaging of Cerebral Physiology

2004 ◽  
Vol 24 (2) ◽  
pp. 191-201 ◽  
Author(s):  
Jonathan P Coles ◽  
Tim D Fryer ◽  
Peter Smielewski ◽  
Kenneth Rice ◽  
John C Clark ◽  
...  
Keyword(s):  
Traumatic Brain Injury ◽  
Blood Flow ◽  
Brain Injury ◽  
Head Injury ◽  
A Priori ◽  
Oxygen Metabolism ◽  
Oxygen Extraction Fraction ◽  
Statistical Accuracy ◽  
Positron Emission ◽  
Cerebral Physiology

Whereas postmortem ischemic damage is common in head injury, antemortem demonstration of ischemia has proven to be elusive. Although 15O positron emission tomography may be useful in this area, the technique has traditionally analyzed data within regions of interest (ROIs) to improve statistical accuracy. In head injury, such techniques are limited because of the lack of a priori knowledge regarding the location of ischemia, coexistence of hyperaemia, and difficulty in defining ischemic cerebral blood flow (CBF) and cerebral oxygen metabolism (CMRO2) levels. We report a novel method for defining disease pathophysiology following head injury. Voxel-based approaches are used to define the distribution of oxygen extraction fraction (OEF) across the entire brain; the standard deviation of this distribution provides a measure of the variability of OEF. These data are also used to integrate voxels above a threshold OEF value to produce an ROI based upon coherent physiology rather than spatial contiguity (the ischemic brain volume; IBV). However, such approaches may suffer from poor statistical accuracy, particularly in regions with low blood flow. The magnitude of these errors has been assessed in modeling experiments using the Hoffman brain phantom and modified control datasets. We conclude that this technique is a valid and useful tool for quantifying ischemic burden after traumatic brain injury.

scholarly journals Analysis of Some Errors in the Measurement of Oxygen Extraction and Oxygen Consumption by the Equilibrium Inhalation Method

1985 ◽  
Vol 5 (4) ◽  
pp. 591-599 ◽  
Author(s):  
John A. Correia ◽  
Nathaniel M. Alpert ◽  
Richard B. Buxton ◽  
Robert H. Ackerman
Keyword(s):  
Systematic Errors ◽  
Oxygen Extraction Fraction ◽  
Oxygen Extraction ◽  
Emission Computed Tomography ◽  
Arterial Blood ◽  
Extraction Fraction ◽  
Positron Emission ◽  
Computed Tomography Scanning ◽  
Subject Motion ◽  
Tomography Scanning

Some sources of error in the equilibrium inhalation method for the measurement of oxygen extraction fraction and CMRO2 by positron emission computed tomography scanning have been evaluated by computer simulation. Emphasis has been placed on errors that have not been thoroughly studied in past work. These include effects of random statistical errors, systematic errors in arterial blood radioactivity concentrations, and errors due to perturbations of the equilibrium state, to tissue inhomogeneity, and to subject motion.

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