scholarly journals Preserved Cerebral Oxygen Metabolism in Astrocytic Dysfunction: A Combination Study of 15O-Gas PET with 14C-Acetate Autoradiography

2019 ◽  
Vol 9 (5) ◽  
pp. 101 ◽  
Author(s):  
Carla Mari Macaisa ◽  
Tadashi Watabe ◽  
Yuwei Liu ◽  
Victor Romanov ◽  
Yasukazu Kanai ◽  
...  
Keyword(s):  
Rat Brain ◽  
Cerebral Blood Volume ◽  
Tca Cycle ◽  
Oxygen Metabolism ◽  
Significant Inhibition ◽  
Oxygen Extraction Fraction ◽  
Metabolic Inhibitor ◽  
High Dose ◽  
Cerebral Oxygen ◽  
Ipsilateral Striatum

Fluorocitrate (FC) is a specific metabolic inhibitor of the tricarboxylic acid (TCA) cycle in astrocytes. The purpose of this study was to evaluate whether inhibition of the astrocyte TCA cycle by FC would affect the oxygen metabolism in the rat brain. At 4 h after the intracranial FC injection, the rats (n = 9) were investigated by 15O-labeled gas PET to measure the cerebral blood flow (CBF), the cerebral metabolic rate of oxygen (CMRO2), oxygen extraction fraction (OEF), and cerebral blood volume (CBV). After the 15O-gas PET, the rats were given an intravenous injection of 14C-acetate for autoradiography. 15O-gas PET showed no significant differences in any of the measured parameters between the ipsilateral and contralateral striatum (high dose group: CBF (54.4 ± 8.8 and 55.3 ± 11.6 mL/100 mL/min), CMRO2 (7.0 ± 0.9 and 7.1 ± 1.2 mL/100 mL/min), OEF (72.0 ± 8.9 and 70.8 ± 8.2%), and CBV (4.1 ± 0.8 and 4.2 ± 0.9 mL/100 mL), respectively). In contrast, the 14C-acetate autoradiography revealed a significant inhibition of the astrocyte metabolism in the ipsilateral striatum. The regional cerebral oxygen consumption as well as the hemodynamic parameters were maintained even in the face of inhibition of the astrocyte TCA cycle metabolism in the rat brain.

scholarly journals PET Quantification of Cerebral Oxygen Metabolism in Small Animals

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Takashi Temma ◽  
Kazuhiro Koshino ◽  
Tetsuaki Moriguchi ◽  
Jun-ichiro Enmi ◽  
Hidehiro Iida
Keyword(s):  
Cerebral Blood Volume ◽  
Animal Experiments ◽  
Oxygen Metabolism ◽  
Cerebrovascular Diseases ◽  
Oxygen Extraction Fraction ◽  
Small Animals ◽  
Cerebral Oxygen ◽  
Technical Problems ◽  
Cerebral Oxygen Metabolism

Understanding cerebral oxygen metabolism is of great importance in both clinical diagnosis and animal experiments because oxygen is a fundamental source of brain energy and supports brain functional activities. Since small animals such as rats are widely used to study various diseases including cerebral ischemia, cerebrovascular diseases, and neurodegenerative diseases, the development of a noninvasivein vivomeasurement method of cerebral oxygen metabolic parameters such as oxygen extraction fraction (OEF) and cerebral metabolic rate of oxygen (CMRO2) as well as cerebral blood flow (CBF) and cerebral blood volume (CBV) has been a priority. Although positron emission tomography (PET) with15O labeled gas tracers has been recognized as a powerful way to evaluate cerebral oxygen metabolism in humans, this method could not be applied to rats due to technical problems and there were no reports of PET measurement of cerebral oxygen metabolism in rats until an15O-O2injection method was developed a decade ago. Herein, we introduce an intravenous administration method using two types of injectable15O-O2and an15O-O2gas inhalation method through an airway placed in the trachea, which enables oxygen metabolism measurements in rats.

scholarly journals Cerebral Oxygen Metabolism after Aneurysmal Subarachnoid Hemorrhage

1991 ◽  
Vol 11 (5) ◽  
pp. 837-844 ◽  
Author(s):  
David A. Carpenter ◽  
Robert L. Grubb ◽  
Lee W. Tempel ◽  
William J. Powers
Keyword(s):  
Subarachnoid Hemorrhage ◽  
Aneurysmal Subarachnoid Hemorrhage ◽  
Oxygen Metabolism ◽  
Brain Regions ◽  
Aneurysm Rupture ◽  
Oxygen Extraction Fraction ◽  
Intracerebral Hematoma ◽  
Cerebral Oxygen ◽  
Cerebral Oxygen Metabolism ◽  
Primary Reduction

Previous studies of cerebral oxygen metabolism and extraction in patients with subarachnoid hemorrhage (SAH) have yielded conflicting results. We used positron emission tomography (PET) to measure the regional cerebral metabolic rate for oxygen (rCMRO2), oxygen extraction fraction (rOEF), and cerebral blood flow (rCBF) 16 times in 11 patients with aneurysmal SAH. All studies were performed preoperatively; no patient had hydrocephalus or intracerebral hematoma on brain CT. Eight patients with no arteriographic vasospasm who were studied on days 1–4 post-SAH had a significant 25% reduction in global CMRO2 compared to age-matched controls, and no significant change in global OEF, suggesting a primary reduction in CMRO2 caused by SAH. Four patients studied seven times during arteriographic vasospasm had significantly increased rOEF with unchanged CMRO2 in arterial territories affected by arteriographic vasospasm compared to territories without vasospasm, indicative of cerebral ischemia without infarction. No brain regions studied with PET were infarcted on follow-up CT. We conclude that the initial aneurysm rupture produces a primary reduction in CMRO2, and that subsequent vasospasm causes ischemia.

scholarly journals Quantitative mapping of cerebral oxygen metabolism using breath-hold calibrated fMRI

2021 ◽  
Author(s):  
Michael Germuska ◽  
Rachael C Stickland ◽  
Antonio Maria Chiarelli ◽  
Hannah L Chandler ◽  
Richard G Wise
Keyword(s):  
Blood Flow ◽  
Oxygen Metabolism ◽  
Oxygen Extraction Fraction ◽  
Arterial Oxygen ◽  
Breath Holding ◽  
Breath Hold ◽  
Neural Function ◽  
Cerebral Oxygen ◽  
Cerebral Oxygen Metabolism

Magnetic resonance imaging (MRI) offers the possibility to non-invasively map the rate of cerebral metabolic oxygen consumption (CMRO2), which is essential for understanding and monitoring neural function in both health and disease. Existing methods of mapping CMRO2, based on respiratory modulation of arterial spin labelling (ASL) and blood oxygen level dependent (BOLD) signals, require lengthy acquisitions and independent modulation of both arterial oxygen and carbon dioxide levels. Here, we present a new simplified method for mapping the rate of cerebral oxygen metabolism that can be performed using a simple breath-holding paradigm. The method incorporates flow-diffusion modelling of oxygen transport and physiological constraints to create a non-linear mapping between the maximum BOLD signal, M, baseline blood flow (CBF0), and CMRO2. A gradient boosted decision tree is used to learn this mapping directly from simulated MRI data. Modelling studies demonstrate that the proposed method is robust to variation in cerebral physiology and metabolism. This new gas-free methodology offers a rapid and pragmatic alternative to existing dual-calibrated methods, removing the need for specialist respiratory equipment and long acquisition times. In-vivo testing of the method, using an 8-minute 45 second protocol of repeated breath-holding, was performed on 15 healthy volunteers, producing quantitative maps of cerebral blood flow (CBF), oxygen extraction fraction (OEF), and CMRO2.

scholarly journals Rapid Quantitative Measurement of CMRO2 and CBF by Dual Administration of 15O-Labeled Oxygen and Water During a Single PET Scan—a Validation Study and Error Analysis in Anesthetized Monkeys

2005 ◽  
Vol 25 (9) ◽  
pp. 1209-1224 ◽  
Author(s):  
Nobuyuki Kudomi ◽  
Takuya Hayashi ◽  
Noboru Teramoto ◽  
Hiroshi Watabe ◽  
Naoki Kawachi ◽  
...  
Keyword(s):  
Repeated Measures ◽  
Cerebral Blood Volume ◽  
Oxygen Metabolism ◽  
Oxygen Extraction Fraction ◽  
Step Method ◽  
Method Error ◽  
Error Sensitivity ◽  
Sequential Administration ◽  
Wide Range ◽  
Present Technique

Cerebral blood flow (CBF) and rate of oxygen metabolism (CMRO2) may be quantified using positron emission tomography (PET) with 15O-tracers, but the conventional three-step technique requires a relatively long study period, attributed to the need for separate acquisition for each of 15O2, H215O, and C15O tracers, which makes the multiple measurements at different physiologic conditions difficult. In this study, we present a novel, faster technique that provides a pixel-by-pixel calculation of CBF and CMRO2 from a single PET acquisition with a sequential administration of 15O2 and H215O. Experiments were performed on six anesthetized monkeys to validate this technique. The global CBF, oxygen extraction fraction (OEF), and CMRO2 obtained by the present technique at rest were not significantly different from those obtained with three-step method. The global OEF (gOEF) also agreed with that determined by simultaneous arterio-sinus blood sampling (gOEFA–V) for a physiologically wide range when changing the arterial PaCO2 ( gOEF = 1.03 gOEFA–V +0.01, P<0.001). The regional values, as well as the image quality were identical between the present technique and three-step method for CBF, OEF, and CMRO2. In addition, a simulation study showed that error sensitivity of the present technique to delay or dispersion of the input function, and the error in the partition coefficient was equivalent to that observed for three-step method. Error sensitivity to cerebral blood volume (CBV) was also identical to that in the three-step and reasonably small, suggesting that a single CBV assessment is sufficient for repeated measures of CBF/CMRO2. These results show that this fast technique has an ability for accurate assessment of CBF/CMRO2 and also allows multiple assessment at different physiologic conditions.

scholarly journals Cerebral Oxygen Metabolism in Neonatal Hypoxic Ischemic Encephalopathy during and after Therapeutic Hypothermia

2013 ◽  
Vol 34 (1) ◽  
pp. 87-94 ◽  
Author(s):  
Mathieu Dehaes ◽  
Alpna Aggarwal ◽  
Pei-Yi Lin ◽  
C Rosa Fortuno ◽  
Angela Fenoglio ◽  
...  
Keyword(s):  
Blood Flow ◽  
Therapeutic Hypothermia ◽  
Cerebral Blood Volume ◽  
Matched Control ◽  
Oxygen Metabolism ◽  
Correlation Spectroscopy ◽  
Hypoxic Ischemic Encephalopathy ◽  
Cerebral Oxygen ◽  
Cerebral Oxygen Metabolism ◽  
Ischemic Encephalopathy

Pathophysiologic mechanisms involved in neonatal hypoxic ischemic encephalopathy (HIE) are associated with complex changes of blood flow and metabolism. Therapeutic hypothermia (TH) is effective in reducing the extent of brain injury, but it remains uncertain how TH affects cerebral blood flow ( CBF) and metabolism. Ten neonates undergoing TH for HIE and seventeen healthy controls were recruited from the NICU and the well baby nursery, respectively. A combination of frequency domain near infrared spectroscopy (FDNIRS) and diffuse correlation spectroscopy (DCS) systems was used to non-invasively measure cerebral hemodynamic and metabolic variables at the bedside. Results showed that cerebral oxygen metabolism ( CMRO 2i) and CBF indices ( CBF i) in neonates with HIE during TH were significantly lower than post-TH and age-matched control values. Also, cerebral blood volume ( CBV) and hemoglobin oxygen saturation ( SO 2) were significantly higher in neonates with HIE during TH compared with age-matched control neonates. Post-TH CBV was significantly decreased compared with values during TH whereas SO 2 remained unchanged after the therapy. Thus, FDNIRS–DCS can provide information complimentary to SO 2 and can assess individual cerebral metabolic responses to TH. Combined FDNIRS–DCS parameters improve the understanding of the underlying physiology and have the potential to serve as bedside biomarkers of treatment response and optimization.

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