scholarly journals Brain Energy Metabolism and Blood Flow Differences in Healthy Aging

2012 ◽  
Vol 32 (7) ◽  
pp. 1177-1187 ◽  
Author(s):  
Joel Aanerud ◽  
Per Borghammer ◽  
M Mallar Chakravarty ◽  
Kim Vang ◽  
Anders B Rodell ◽  
...  
Keyword(s):  
Blood Flow ◽  
Healthy Volunteers ◽  
Healthy Aging ◽  
Brain Aging ◽  
Temporal Cortex ◽  
Oxygen Extraction Fraction ◽  
Positron Emission ◽  
Rate Of Oxygen Consumption ◽  
Parietal Cortices ◽  
The Brain

Cerebral metabolic rate of oxygen consumption ( CMRO 2), cerebral blood flow ( CBF), and oxygen extraction fraction ( OEF) are important indices of healthy aging of the brain. Although a frequent topic of study, changes of CBF and CMRO 2 during normal aging are still controversial, as some authors find decreases of both CBF and CMRO 2 but increased OEF, while others find no change, and yet other find divergent changes. In this reanalysis of previously published results from positron emission tomography of healthy volunteers, we determined CMRO 2 and CBF in 66 healthy volunteers aged 21 to 81 years. The magnitudes of CMRO 2 and CBF declined in large parts of the cerebral cortex, including association areas, but the primary motor and sensory areas were relatively spared. We found significant increases of OEF in frontal and parietal cortices, excluding primary motor and somatosensory regions, and in the temporal cortex. Because of the inverse relation between OEF and capillary oxygen tension, increased OEF can compromise oxygen delivery to neurons, with possible perturbation of energy turnover. The results establish a possible mechanism of progression from healthy to unhealthy brain aging, as the regions most affected by age are the areas that are most vulnerable to neurodegeneration.

scholarly journals Diffuse Optical Tomography of Cerebral Blood Flow, Oxygenation, and Metabolism in Rat during Focal Ischemia

2003 ◽  
Vol 23 (8) ◽  
pp. 911-924 ◽  
Author(s):  
Joseph P Culver ◽  
Turgut Durduran ◽  
Daisuke Furuya ◽  
Cecil Cheung ◽  
Joel H Greenberg ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Cerebral Blood Volume ◽  
Optical Tomography ◽  
Diffuse Optical Tomography ◽  
Artery Occlusion ◽  
Oxygen Extraction Fraction ◽  
Metabolic Imaging ◽  
Positron Emission ◽  
Rate Of Oxygen Consumption

Diffuse optical tomography (DOT) is an attractive approach for evaluating stroke physiology. It provides hemodynamic and metabolic imaging with unique potential for continuous noninvasive bedside imaging in humans. To date there have been few quantitative spatial-temporal studies of stroke pathophysiology based on diffuse optical signatures. The authors report DOT images of hemodynamic and metabolic contrasts using a rat middle cerebral artery occlusion (MCAO) stroke model. This study used a novel DOT device that concurrently obtains coregistered images of relative cerebral blood volume (rCBV), tissue-averaged hemoglobin oxygen saturation (Sto2), and relative cerebral blood flow (rCBF). The authors demonstrate how these hemodynamic measures can be synthesized to calculate an index of the oxygen extraction fraction (OEF) and the cerebral metabolic rate of oxygen consumption (CMRo2). Temporary (60-minute) MCAO was performed on five rats. Ischemic changes, averaged over the 60 minutes of occlusion, were as follows: rCBF = 0.42 ± 0.04, rCBV = 1.02 ± 0.04, ΔSto2 = −11 ± 2%, rOEF = 1.39 ± 0.06 and rCMRo2 = 0.59 ± 0.07. Although rOEF increased in response to decreased blood flow, rCMRo2 decreased. The sensitivity of this method of DOT analysis is discussed in terms of assumptions about baseline physiology, and the diffuse optical results are compared with positron emission tomography, magnetic resonance imaging, and histology observations in the literature.

Longitudinal Changes in Individual BrainAGE in Healthy Aging, Mild Cognitive Impairment, and Alzheimer’s Disease

GeroPsych ◽  
2012 ◽  
Vol 25 (4) ◽  
pp. 235-245 ◽  
Author(s):  
Katja Franke ◽  
Christian Gaser
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Healthy Aging ◽  
Brain Aging ◽  
Elderly Subjects ◽  
Additional Increase ◽  
Longitudinal Changes ◽  
Novel Method ◽  
The Brain

We recently proposed a novel method that aggregates the multidimensional aging pattern across the brain to a single value. This method proved to provide stable and reliable estimates of brain aging – even across different scanners. While investigating longitudinal changes in BrainAGE in about 400 elderly subjects, we discovered that patients with Alzheimer’s disease and subjects who had converted to AD within 3 years showed accelerated brain atrophy by +6 years at baseline. An additional increase in BrainAGE accumulated to a score of about +9 years during follow-up. Accelerated brain aging was related to prospective cognitive decline and disease severity. In conclusion, the BrainAGE framework indicates discrepancies in brain aging and could thus serve as an indicator for cognitive functioning in the future.

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.

scholarly journals Measurement of Cerebral Blood Flow in the Rat with Intravenous Injection of [11C]Butanol by External Coincidence Counting: A Repeatable and Noninvasive Method in the Brain

1984 ◽  
Vol 4 (2) ◽  
pp. 275-283 ◽  
Author(s):  
Shigeharu Takagi ◽  
Kazumasa Ehara ◽  
Peter J. Kenny ◽  
Ronald D. Finn ◽  
Paresh J. Kothari ◽  
...  
Keyword(s):  
Blood Flow ◽  
Rat Brain ◽  
Intravenous Injection ◽  
Regression Line ◽  
Oxygen Extraction Fraction ◽  
Minimum Loss ◽  
Coincidence Counting ◽  
Extraction Fraction ◽  
The Brain ◽  
Large Vessels

No method has been reported for measuring CBF, repeatedly and noninvasively, in the rat brain. A new method is described, which is noninvasive to the brain, skull, or cervical large vessels. Two pairs of coincidence detectors were positioned, one over the rat brain and the other at the loop of a catheter inserted into the femoral artery. The coincidence head curve and arterial curve were recorded after intravenous injection of 1-[11C]butanol in 15 rats. CBF was calculated by one-compartment curve fitting (CBFo) from 1-min data and with the recirculation corrected height/area method from 3-min data (CBFh · 3min) and 5-min data (CBFh · 5min). CBFo agreed well with CBFh · 5min, although a slight overestimation was observed in CBFh · 3min. The normal CBFo in the normocapnic group (n = 6, paco2 36.7 ± 2.3 mm Hg) was 1.76 ± 0.49 ml/g min (mean ± SD). A good correlation was observed between CBFo ( y) and Paco2 ( x), and the regression line was y = 0.0629 x – 0.715 (r = 0.88, p < 0.0001). We concluded that this method gives the stable blood flow values noninvasively and with a minimum loss of blood (<0.28 ml per measurement). Applications of this method include activation studies, studies on the effect of drugs and treatments, and water and oxygen extraction fraction studies using different tracers in the same rat.

scholarly journals Cerebral [15O] Water Clearance in Humans Determined by Positron Emission Tomography: II. Vascular Responses to Vibrotactile Stimulation

1997 ◽  
Vol 17 (1) ◽  
pp. 73-79 ◽  
Author(s):  
Hitoshi Fujita ◽  
Ernst Meyer ◽  
David C. Reutens ◽  
Hiroto Kuwabara ◽  
Alan C. Evans ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Blood Flow ◽  
Emission Tomography ◽  
Mr Images ◽  
Vibrotactile Stimulation ◽  
Positron Emission ◽  
The Right ◽  
The Brain ◽  
Hand Area ◽  
Water Clearance

When used to measure blood flow, water leaves a residue in the vascular bed, which may contribute to the calculation of increased blood flow during functional activation of brain tissue. To assess the magnitude of this contribution with the two-compartment positron emission tomography (PET) method, we mapped the water clearance ( K1) of the brain as an index of cerebral blood flow (CBF) and the apparent vascular distribution of nonextracted H215O ( Vo). The latter map represented mainly the cerebral arterial and arteriolar volume. We also prepared subtraction maps (Δ K1, Δ Vo) of the response to vibrotactile stimulation of the fingertips of the right hand of six normal volunteers. Using magnetic resonance (MR) images of all subjects, the data were rendered into Talairach's stereotaxic coordinates and the averaged subtraction images (activation minus baseline) merged with the corresponding averaged MRI image. The Δ K1 map revealed the expected response in the primary sensory hand area; the Δ Vo response was located about 13 mm more anteriorly, close to the central fissure, most likely reflecting changes of the arteries feeding the primary sensory hand area. We conclude that cerebral perfusion and cerebrovascular responses to vibrotactile stimulation may occur in disparate locations that can be identified separately by using the two-compartment method.

Cerebral Physiology

2019 ◽  
pp. 27-34
Author(s):  
Stefan Bittner ◽  
Kerstin Göbel ◽  
Sven G. Meuth
Keyword(s):  
Blood Flow ◽  
Intracranial Pressure ◽  
Patient Management ◽  
Cerebral Metabolism ◽  
Hypoxic Conditions ◽  
Anaesthetic Agents ◽  
Rate Of Oxygen Consumption ◽  
Cerebral Physiology ◽  
Dose Dependent ◽  
The Brain

This chapter reviews the physiology of cerebral metabolism and cerebral blood flow (CBF), the effects of anaesthetic agents on cerebral physiology, and, most importantly, their effects on the CBF and metabolism. Adequate CBF to all regions of the brain is essential as cerebral tissue is intolerant of hypoxic conditions. Anaesthetic agents cause dose-dependent and reversible effects on important physiological cerebral parameters, including intracranial pressure, CBF, and cerebral metabolic rate of oxygen consumption (as a parameter of cerebral metabolism). These changes can either be of clinical therapeutic importance or need to be taken into account during patient management to avoid unwanted side effects. In neuroanaesthesia, considerable emphasis is placed on the manner in which anaesthetics influence the CBF as a surrogate parameter of cerebral metabolism, including how modest alterations in the CBF can substantially influence neuronal outcome, and how CBF control is central to the management of intracranial pressure.

Neuroprotection in hypothermia linked to redistribution of oxygen in brain

2003 ◽  
Vol 285 (1) ◽  
pp. H17-H25 ◽  
Author(s):  
Masaharu Sakoh ◽  
Albert Gjedde
Keyword(s):  
Blood Flow ◽  
Oxygen Consumption ◽  
Energy Metabolism ◽  
Brain Tissue ◽  
Traumatic Injury ◽  
Oxygen Extraction Fraction ◽  
Physiological Variables ◽  
Cerebral Metabolic Rate ◽  
Extraction Fraction ◽  
The Brain

Hypothermia improves the outcome of acute ischemic stroke, traumatic injury, and inflammation of brain tissue. We tested the hypothesis that hypothermia reduces the energy metabolism of brain tissue to a level that is commensurate with the prevailing blood flow and hence allows adequate distribution of oxygen to the entire tissue. To determine the effect of 32°C hypothermia on brain tissue, we measured the sequential changes of physiological variables by means of PET in pigs. Cerebral blood flow and oxygen consumption (cerebral metabolic rate of oxygen) declined to 50% of the baseline in 3 and 5 h, respectively, thus elevating the oxygen extraction fraction to 140% of the baseline at 3 h. The results are consistent with the claim that cooling of the brain to 32°C couples both energy metabolism and blood flow to a lower rate of work of the entire tissue.

scholarly journals Evaluation of the 11CO2 Positron Emission Tomographic Method for Measuring Brain pH. II. Quantitative pH Mapping in Patients with Ischemic Cerebrovascular Diseases

1989 ◽  
Vol 9 (6) ◽  
pp. 859-873 ◽  
Author(s):  
Michio Senda ◽  
Nathaniel M. Alpert ◽  
Bruce C. Mackay ◽  
Richard B. Buxton ◽  
John A. Correia ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cell Membrane ◽  
Extracellular Volume ◽  
Membrane Integrity ◽  
Oxygen Extraction Fraction ◽  
Stroke Patients ◽  
Cell Membrane Integrity ◽  
Extraction Fraction ◽  
Positron Emission ◽  
Contralateral Cortex

A practical method has been developed that, using 11CO2 and positron emission tomography (PET), computes and maps (a) “effective pH” (pHt), a weighted average of intra- and extracellular pH, and (b) “clearance” ( K1), product of blood flow and 11CO2 extraction. This method, together with measurements of cerebral blood flow (CBF) and oxygen extraction fraction (OEF), was applied to 12 patients with cerebral ischemia or stroke. The regional K1 was positively correlated with CBF ( n = +0.78). The k1/CBF ratio, representing the extraction fraction ratio of 11CO2 to H215O, was negatively correlated with CBF ( r = –0.54), suggesting that 11CO2 extraction decreases as flow increases. In five acute stroke patients within 2 days of onset, the injured cortex had lower CBF (20.6 ml/min/100 g), higher OEF (78.1%), and lower pHt (6.96) than the contralateral cortex (CBF = 41.4 ml/min/100 g, OEF = 53.3%, pHt = 7.00), suggesting intracellular acidosis with intact cell membranes. In three stroke patients 5–8 days after onset, the injured cortex had higher CBF (60.9 ml/min/100 g), lower OEF (32.0%), and higher pHt (7.12) than the contralateral cortex (CBF = 45.3 ml/min/100 g, OEF = 58.0%, pHt = 7.06), which suggested an increase in extracellular volume compartment reflecting loss of cell membrane integrity. This method provides information on the regional tissue acid–base status and cell membrane integrity, which may be prognostic of tissue viability.

scholarly journals Model Dependency and Estimation Reliability in Measurement of Cerebral Oxygen Utilization Rate with Oxygen-15 and Dynamic Positron Emission Tomography

1986 ◽  
Vol 6 (1) ◽  
pp. 105-119 ◽  
Author(s):  
Sung-Cheng Huang ◽  
DaGan Feng ◽  
Michael E. Phelps
Keyword(s):  
Positron Emission Tomography ◽  
Blood Flow ◽  
Low Noise ◽  
Emission Tomography ◽  
Oxygen Extraction Fraction ◽  
Vascular Volume ◽  
Dynamic Positron Emission Tomography ◽  
Extraction Fraction ◽  
Positron Emission ◽  
Model Configuration

The use of oxygen-15 and dynamic positron emission tomography (PET) for the measurement of CMRO was investigated in terms of the achievable accuracy of CMRO and its sensitivity to model configuration assumed in the estimation. Three models of different descriptions for the vascular radioactivity in tissue were examined by computer simulation. By simulating the tracer kinetics with one model and curve fitting them with another, it was found that the CMRO measurement was very sensitive to the model configuration used and it needed kinetic data of low noise level to determine the correct model to use. The approach of sensitivity functions and covariance matrices was used to examine the estimation reliability and error propagation of the model parameters. It was found that for all three model configurations examined the reliability of the CMRO estimate was dependent on the blood flow and oxygen extraction fraction in tissue (∼2% in tissues of high blood flow and normal extraction and 10% in tissues of low blood flow and low extraction fraction, in a study of 1 × 106 counts/brain slice in 3 min). The estimation reliability is drastically decreased if the total data collection time is reduced to 1 min but is not critically sensitive to the scan sampling interval used. Estimating blood flow or vascular volume simultaneously with CMRO will reduce the reliability of the CMRO estimate by ∼50%. Propagation of parameter error from blood flow or vascular volume to CMRO is dependent on the model configuration as well as the scanning schedule and estimation procedure used. Results from the study provide useful information for improving the study procedure of CMRO measurements. The present study also illustrates a general representation of PET measurements and an approach that can be applied to other tracer techniques in PET for selecting appropriate model configurations and for designing proper experimental procedures.

scholarly journals Synthesis and evaluation of N-isopropyl-p-[11C]methylamphetamine as a novel cerebral blood flow tracer for positron emission tomography

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Jun Toyohara ◽  
Norihiro Harada ◽  
Takeharu Kakiuchi ◽  
Hiroyuki Ohba ◽  
Masakatsu Kanazawa ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Emission Tomography ◽  
Emission Computed Tomography ◽  
Normal Brain ◽  
Brain Uptake ◽  
Pet Tracer ◽  
Positron Emission ◽  
The Brain

Abstract Introduction Increases in fasting plasma glucose (PG) levels lead to a decrease in 2-deoxy-2-[18F]fluoro-d-glucose ([18F]FDG) uptake in the normal brain, especially in the precuneus, resulting in an Alzheimer’s disease (AD)-like uptake pattern. Therefore, patients with higher PG levels, such as those with diabetes, can be erroneously diagnosed with AD when positron emission tomography (PET) imaging is done using [18F]FDG, due to reduced uptake of [18F]FDG in the precuneus. To help avoid an erroneous diagnosis of AD due to differences in glucose metabolism, evaluating cerebral blood flow (CBF) in the brain is useful. However, current techniques such as single photon emission computed tomography (SPECT) and [15O]H2O PET have limitations regarding early diagnosis of AD because the images they produce are of low resolution. Here, we developed a novel CBF PET tracer that may be more useful than [18F]FDG for diagnosis of AD. Methods We synthesized and evaluated N-isopropyl-p-[11C]methylamphetamine ([11C]4) as a carbon-11-labeled analogue of the standard CBF SPECT tracer N-isopropyl-p-[123I]iodoamphetamine. Fundamental biological evaluations such as biodistribution, peripheral metabolism in mice, and brain kinetics of [11C]4 in non-human primates with PET with successive measurement of [15O]H2O were performed. Results [11C]4 was synthesized by methylation of the corresponding tributyltin precursor (2) with [11C]MeI in a palladium-promoted Stille cross-coupling reaction. The brain uptake of [11C]4 in mice peaked at 5–15 min after injection and then promptly decreased. Most radioactivity in the brain was detected in the unchanged form, although in the periphery, [11C]4 was rapidly metabolized to hydrophilic components. Acetazolamide (AZM) treatment significantly increased the brain uptake of [11C]4 without affecting the blood levels of radioactivity in mice. Preliminary kinetics analysis showed that the K1 of [11C]4 reflected regional CBF in a vehicle-treated monkey, but that the K1 did not reflect CBF in higher flow regions after AZM loading. Conclusion [11C]4 is a potential novel CBF PET tracer. Further validation studies are needed before [11C]4 can be used in humans.

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