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McAlinden N, Reiche CF, Clark AM, Scharf R, Cheng Y, Sharma R, Rieth L, Dawson MD, Angelucci A, Mathieson K, Blair S. In vivo optogenetics using a Utah Optrode Array with enhanced light output and spatial selectivity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.18.585479. [PMID: 38562871 PMCID: PMC10983961 DOI: 10.1101/2024.03.18.585479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Optogenetics allows manipulation of neural circuits in vivo with high spatial and temporal precision. However, combining this precision with control over a significant portion of the brain is technologically challenging (especially in larger animal models). Here, we have developed, optimised, and tested in vivo, the Utah Optrode Array (UOA), an electrically addressable array of optical needles and interstitial sites illuminated by 181 µLEDs and used to optogenetically stimulate the brain. The device is specifically designed for non-human primate studies. Thinning the combined µLED and needle backplane of the device from 300 µm to 230 µm improved the efficiency of light delivery to tissue by 80%, allowing lower µLED drive currents, which improved power management and thermal performance. The spatial selectivity of each site was also improved by integrating an optical interposer to reduce stray light emission. These improvements were achieved using an innovative fabrication method to create an anodically bonded glass/silicon substrate with through-silicon vias etched, forming an optical interposer. Optical modelling was used to demonstrate that the tip structure of the device had a major influence on the illumination pattern. The thermal performance was evaluated through a combination of modelling and experiment, in order to ensure that cortical tissue temperatures did not rise by more than 1°C. The device was tested in vivo in the visual cortex of macaque expressing ChR2-tdTomato in cortical neurons. It was shown that the strongest optogenetic response occurred in the region surrounding the needle tips, and that the extent of the optogenetic response matched the predicted illumination profile based on optical modelling - demonstrating the improved spatial selectivity resulting from the optical interposer approach. Furthermore, different needle illumination sites generated different patterns of low-frequency potential (LFP) activity.
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Oliveira AMP, De Andrade AF, Pipek LZ, Iaccarino C, Rubiano AM, Amorim RL, Teixeira MJ, Paiva WS. New perspectives on assessment and understanding of the patient with cranial bone defect: a morphometric and cerebral radiodensity assessment. Front Surg 2024; 11:1329019. [PMID: 38379817 PMCID: PMC10876786 DOI: 10.3389/fsurg.2024.1329019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 01/24/2024] [Indexed: 02/22/2024] Open
Abstract
Background Skull defects after decompressive craniectomy (DC) cause physiological changes in brain function and patients can have neurologic symptoms after the surgery. The objective of this study is to evaluate whether there are morphometric changes in the cortical surface and radiodensity of brain tissue in patients undergoing cranioplasty and whether those variables are correlated with neurological prognosis. Methods This is a prospective cohort with 30 patients who were submitted to cranioplasty and followed for 6 months. Patients underwent simple head CT before and after cranioplasty for morphometric and cerebral radiodensity assessment. A complete neurological exam with Mini-Mental State Examination (MMSE), modified Rankin Scale, and the Barthel Index was performed to assess neurological prognosis. Results There was an improvement in all symptoms of the syndrome of the trephined, specifically for headache (p = 0.004) and intolerance changing head position (p = 0.016). Muscle strength contralateral to bone defect side also improved (p = 0.02). Midline shift of intracranial structures decreased after surgery (p = 0.004). The Anterior Distance Difference (ADif) and Posterior Distance Difference (PDif) were used to assess morphometric changes and varied significantly after surgery. PDif was weakly correlated with MMSE (p = 0.03; r = -0.4) and Barthel index (p = 0.035; r = -0.39). The ratio between the radiodensities of gray matter and white matter (GWR) was used to assess cerebral radiodensity and was also correlated with MMSE (p = 0.041; r = -0.37). Conclusion Morphological anatomy and radiodensity of the cerebral cortex can be used as a tool to assess neurological prognosis after DC.
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Affiliation(s)
- Arthur Maynart Pereira Oliveira
- Department of Neurosurgery, Hospital das Clínicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, São Paulo, Brazil
| | - Almir Ferreira De Andrade
- Department of Neurosurgery, Hospital das Clínicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, São Paulo, Brazil
| | - Leonardo Zumerkorn Pipek
- Department of Neurology, Hospital das Clínicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, São Paulo, Brazil
| | - Corrado Iaccarino
- Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Andres M. Rubiano
- Department of Neurosurgery, Universidad de Bogotá Jorge Tadeo Lozano, Bogotá, Colombia
- Centre for Neuroscience in Education, University of Cambridge, Cambridge, United Kingdom
| | - Robson Luis Amorim
- Department of Neurosurgery, Hospital das Clínicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, São Paulo, Brazil
| | - Manoel Jacobsen Teixeira
- Department of Neurosurgery, Hospital das Clínicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, São Paulo, Brazil
| | - Wellingson Silva Paiva
- Department of Neurosurgery, Hospital das Clínicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, São Paulo, Brazil
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Buxton RB. Thermodynamic limitations on brain oxygen metabolism: physiological implications. J Physiol 2024; 602:683-712. [PMID: 38349000 DOI: 10.1113/jp284358] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Accepted: 01/03/2024] [Indexed: 02/20/2024] Open
Abstract
Recent thermodynamic modelling indicates that maintaining the brain tissue ratio of O2 to CO2 (abbreviated tissue O2 /CO2 ) is critical for preserving the entropy increase available from oxidative metabolism of glucose, with a fall of that available entropy leading to a reduction of the phosphorylation potential and impairment of brain energy metabolism. This provides a novel perspective for understanding physiological responses under different conditions in terms of preserving tissue O2 /CO2 . To enable estimation of tissue O2 /CO2 in the human brain, a detailed mathematical model of O2 and CO2 transport was developed, and applied to reported physiological responses to different challenges, asking: how well is tissue O2 /CO2 preserved? Reported experimental results for increased neural activity, hypercapnia and hypoxia due to high altitude are consistent with preserving tissue O2 /CO2 . The results highlight two physiological mechanisms that control tissue O2 /CO2 : cerebral blood flow, which modulates tissue O2 ; and ventilation rate, which modulates tissue CO2 . The hypoxia modelling focused on humans at high altitude, including acclimatized lowlanders and Tibetan and Andean adapted populations, with a primary finding that decreasing CO2 by increasing ventilation rate is more effective for preserving tissue O2 /CO2 than increasing blood haemoglobin content to maintain O2 delivery to tissue. This work focused on the function served by particular physiological responses, and the underlying mechanisms require further investigation. The modelling provides a new framework and perspective for understanding how blood flow and other physiological factors support energy metabolism in the brain under a wide range of conditions. KEY POINTS: Thermodynamic modelling indicates that preserving the O2 /CO2 ratio in brain tissue is critical for preserving the entropy change available from oxidative metabolism of glucose and the phosphorylation potential underlying energy metabolism. A detailed model of O2 and CO2 transport was developed to allow estimation of the tissue O2 /CO2 ratio in the human brain in different physiological states. Reported experimental results during hypoxia, hypercapnia and increased oxygen metabolic rate in response to increased neural activity are consistent with maintaining brain tissue O2 /CO2 ratio. The hypoxia modelling of high-altitude acclimatization and adaptation in humans demonstrates the critical role of reducing CO2 with increased ventilation for preserving tissue O2 /CO2 . Preservation of tissue O2 /CO2 provides a novel perspective for understanding the function of observed physiological responses under different conditions in terms of preserving brain energy metabolism, although the mechanisms underlying these functions are not well understood.
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Affiliation(s)
- Richard B Buxton
- Center for Functional Magnetic Resonance Imaging, Department of Radiology, University of California, San Diego, California, USA
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Diprose WK, Rao A, Ghate K, Dyer Z, Campbell D, Almekhlafi M, Barber PA. Penumbral cooling in ischemic stroke with intraarterial, intravenous or active conductive head cooling: A thermal modeling study. J Cereb Blood Flow Metab 2024; 44:66-76. [PMID: 37734834 PMCID: PMC10905634 DOI: 10.1177/0271678x231203025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 08/08/2023] [Accepted: 08/12/2023] [Indexed: 09/23/2023]
Abstract
In ischemic stroke, selectively cooling the ischemic penumbra might lead to neuroprotection while avoiding systemic complications. Because penumbral tissue has reduced cerebral blood flow and in vivo brain temperature measurement remains challenging, the effect of different methods of therapeutic hypothermia on penumbral temperature are unknown. We used the COMSOL Multiphysics® software to model a range of cases of therapeutic hypothermia in ischemic stroke. Four ischemic stroke models were developed with ischemic core and/or penumbra volumes between 33-300 mL. Four experiments were performed on each model, including no cooling, and intraarterial, intravenous, and active conductive head cooling. The steady-state temperature of the non-ischemic brain, ischemic penumbra, and ischemic core without cooling was 37.3 °C, 37.5-37.8 °C, and 38.9-39.4 °C respectively. Intraarterial, intravenous and active conductive head cooling reduced non-ischemic brain temperature by 4.3 °C, 2.1 °C, and 0.7-0.8 °C respectively. Intraarterial, intravenous and head cooling reduced the temperature of the ischemic penumbra by 3.9-4.3 °C, 1.9-2.1 °C, and 1.2-3.4 °C respectively. Active conductive head cooling was the only method to selectively reduce penumbral temperature. Clinical studies that measure brain temperature in ischemic stroke patients undergoing therapeutic hypothermia are required to validate these hypothesis-generating findings.
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Affiliation(s)
- William K Diprose
- Department of Medicine, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
- Department of Neurology, Auckland City Hospital, Auckland, New Zealand
| | - Avinash Rao
- Department of Engineering, Victoria University of Wellington, Wellington, New Zealand
| | - Kaustubha Ghate
- Department of Neurology, Auckland City Hospital, Auckland, New Zealand
| | - Zoe Dyer
- Department of Neurology, Auckland City Hospital, Auckland, New Zealand
| | - Doug Campbell
- Department of Anesthesia and Perioperative Medicine, Auckland City Hospital, Auckland, New Zealand
| | | | - P Alan Barber
- Department of Medicine, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
- Department of Neurology, Auckland City Hospital, Auckland, New Zealand
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Sun H, Li B, Liu J, Xi X, Zhang L, Zhang Y, Li G, Guo H, Gu K, Wang T, Wen C, Liu Y. Real-time model-based cerebral perfusion calculation for ischemic stroke. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2024; 243:107916. [PMID: 37976610 DOI: 10.1016/j.cmpb.2023.107916] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 10/30/2023] [Accepted: 11/05/2023] [Indexed: 11/19/2023]
Abstract
BACKGROUND AND OBJECTIVES Clinical diagnosis of ischemic stroke commonly relies on examining cerebral perfusion changes by using computed tomography perfusion (CTP) techniques. However, the radiation dose in CTP is quite higher in comparison to computed tomography angiography (CTA), with associated costs and time. METHODS Hence, this study established a lumped-parameter model (LPM) of brain tissue microcirculation (BTM) based on CTA, aiming to achieve real-time calculation of cerebral perfusion. After validation of calculated flow results with clinical data, the BTM-LPM model was used to examine the changes in cerebral perfusion following ischemic stroke, in which the effects of nine anatomical structures of the Circle of Willis (CoW) together with various distribution patterns of stenosis in the feeding arteries were considered. RESULTS When compared the calculated flow results from BTM-LPM with the clinically measured data of literature, the mean squared error (MSE) value for the feeding arteries was 3.9 % and its total value for microcirculatory flow in each region was 0.1 %. Notably, the calculation time was 35.6 s. In the case of the CoW missing the left and right posterior communicating artery, a 60 % stenosis of the basilar artery is likely to cause ischemic damage to some temporal and occipital lobes of the right and left hemispheres. While in the case of the CoW missing the anterior communicating artery and the left posterior communicating artery, ischemic damage to the entire frontal lobe and parts of the temporal and parietal lobes of the left hemisphere was found when 80 % stenosis occurred in the left internal carotid artery. CONCLUSIONS The BTM-LPM proposed in this study could accurately calculate cerebral perfusion in real time and demonstrated the importance of CoW anatomy in different ischemic injuries to cerebral tissue. The calculated cerebral perfusion would be a reference value for early diagnosis and preoperative planning of different ischemic injuries to cerebral tissue, thereby the BTM-LPM holds great promising for replacing CTP examination.
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Affiliation(s)
- Hao Sun
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, No. 100 Pingleyuan, Chaoyang, Beijing 100124, China
| | - Bao Li
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, No. 100 Pingleyuan, Chaoyang, Beijing 100124, China
| | - Jincheng Liu
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, No. 100 Pingleyuan, Chaoyang, Beijing 100124, China
| | - Xiaolu Xi
- Wuhan United Imaging Healthcare Surgical Technology Co., Ltd. Hubei, China
| | - Liyuan Zhang
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, No. 100 Pingleyuan, Chaoyang, Beijing 100124, China
| | - Yanping Zhang
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, No. 100 Pingleyuan, Chaoyang, Beijing 100124, China
| | - Guangfei Li
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, No. 100 Pingleyuan, Chaoyang, Beijing 100124, China
| | - Huamei Guo
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, No. 100 Pingleyuan, Chaoyang, Beijing 100124, China
| | - Kenan Gu
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, No. 100 Pingleyuan, Chaoyang, Beijing 100124, China
| | - Tongna Wang
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, No. 100 Pingleyuan, Chaoyang, Beijing 100124, China
| | - Chuanqi Wen
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, No. 100 Pingleyuan, Chaoyang, Beijing 100124, China
| | - Youjun Liu
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, No. 100 Pingleyuan, Chaoyang, Beijing 100124, China.
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Oliva V, Riegner G, Dean J, Khatib LA, Allen A, Barrows D, Chen C, Fuentes R, Jacobson A, Lopez C, Mosbey D, Reyes M, Ross J, Uvarova A, Liu T, Mobley W, Zeidan F. WITHDRAWN: I feel your pain: Higher empathy is associated with higher posterior default mode network activity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.11.553004. [PMID: 37645854 PMCID: PMC10462016 DOI: 10.1101/2023.08.11.553004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
The authors discovered an error in the primary analysis and have withdrawn the results from this version of the investigation.
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Stoll EA. A thermodynamical model of non-deterministic computation in cortical neural networks. Phys Biol 2023; 21:016003. [PMID: 38078366 DOI: 10.1088/1478-3975/ad0f2d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 11/23/2023] [Indexed: 12/18/2023]
Abstract
Neuronal populations in the cerebral cortex engage in probabilistic coding, effectively encoding the state of the surrounding environment with high accuracy and extraordinary energy efficiency. A new approach models the inherently probabilistic nature of cortical neuron signaling outcomes as a thermodynamic process of non-deterministic computation. A mean field approach is used, with the trial Hamiltonian maximizing available free energy and minimizing the net quantity of entropy, compared with a reference Hamiltonian. Thermodynamic quantities are always conserved during the computation; free energy must be expended to produce information, and free energy is released during information compression, as correlations are identified between the encoding system and its surrounding environment. Due to the relationship between the Gibbs free energy equation and the Nernst equation, any increase in free energy is paired with a local decrease in membrane potential. As a result, this process of thermodynamic computation adjusts the likelihood of each neuron firing an action potential. This model shows that non-deterministic signaling outcomes can be achieved by noisy cortical neurons, through an energy-efficient computational process that involves optimally redistributing a Hamiltonian over some time evolution. Calculations demonstrate that the energy efficiency of the human brain is consistent with this model of non-deterministic computation, with net entropy production far too low to retain the assumptions of a classical system.
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Affiliation(s)
- Elizabeth A Stoll
- Western Institute for Advanced Study, Denver, Colorado, United States of America
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Chung KJ, De Sarno D, Lee TY. CT perfusion stroke lesion threshold calibration between deconvolution algorithms. Sci Rep 2023; 13:21458. [PMID: 38052882 PMCID: PMC10698076 DOI: 10.1038/s41598-023-48700-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Accepted: 11/29/2023] [Indexed: 12/07/2023] Open
Abstract
CTP is an important diagnostic tool in managing patients with acute ischemic stroke, but challenges persist in the agreement of stroke lesion volumes and ischemic core-penumbra mismatch profiles determined with different CTP post-processing software. We investigated a systematic method of calibrating CTP stroke lesion thresholds between deconvolution algorithms using a digital perfusion phantom to improve inter-software agreement of mismatch profiles. Deconvolution-estimated cerebral blood flow (CBF) and Tmax was compared to the phantom ground truth via linear regression for one model-independent and two model-based deconvolution algorithms. Using the clinical standard of model-independent CBF < 30% and Tmax > 6 s as reference thresholds for ischemic core and penumbra, respectively, we determined that model-based CBF < 15% and Tmax > 6 s were the corresponding calibrated thresholds after accounting for quantitative differences revealed at linear regression. Calibrated thresholds were then validated in 63 patients with large vessel stroke by evaluating agreement (concordance and Cohen's kappa, κ) between the two model-based and model-independent deconvolution methods in determining mismatch profiles used for clinical decision-making. Both model-based deconvolution methods achieved 95% concordance with model-independent assessment and Cohen's kappa was excellent (κ = 0.87; 95% confidence interval [CI] 0.72-1.00 and κ = 0.86; 95% CI 0.70-1.00). Our systematic method of calibrating CTP stroke lesion thresholds may help harmonize mismatch profiles determined by different software.
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Affiliation(s)
- Kevin J Chung
- Department of Medical Biophysics, University of Western Ontario, London, ON, Canada
- Robarts Research Institute, University of Western Ontario, London, ON, Canada
- Imaging Program, Lawson Health Research Institute, London, ON, Canada
| | - Danny De Sarno
- Robarts Research Institute, University of Western Ontario, London, ON, Canada
- Imaging Program, Lawson Health Research Institute, London, ON, Canada
| | - Ting-Yim Lee
- Department of Medical Biophysics, University of Western Ontario, London, ON, Canada.
- Robarts Research Institute, University of Western Ontario, London, ON, Canada.
- Imaging Program, Lawson Health Research Institute, London, ON, Canada.
- Department of Medical Imaging, University of Western Ontario, London, ON, Canada.
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Li Z, Chen D, Li Z, Fan H, Guo L, Sui B, Ventikos Y. A computational study of fluid transport characteristics in the brain parenchyma of dementia subtypes. J Biomech 2023; 159:111803. [PMID: 37734184 DOI: 10.1016/j.jbiomech.2023.111803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 09/15/2023] [Indexed: 09/23/2023]
Abstract
The cerebral environment is a complex system consisting of parenchymal tissue and multiple fluids. Dementia is a common class of neurodegenerative diseases, caused by structural damages and functional deficits in the cerebral environment. In order to better understand the pathology of dementia from a cerebral fluid transport angle and provide clearer evidence that could help differentiate between dementia subtypes, such as Alzheimer's disease and vascular dementia, we conducted fluid-structure interaction modelling of the brain using a multiple-network poroelasticity model, which considers both neuropathological and cerebrovascular factors. The parenchyma was further subdivided and labelled into parcellations to obtain more localised and detailed data. The numerical results were converted to computed functional images by an in-house workflow. Different cerebral blood flow (CBF) and cerebrospinal fluid (CSF) clearance abnormalities were identified in the modelling results, when comparing Alzheimer's disease and vascular dementia. This paper presents our preliminary results as a proof of concept for a novel clinical diagnostic tool, and paves the way for a larger clinical study.
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Affiliation(s)
- Zeyan Li
- Wenzhou Safety (Emergency) Institute, Tianjin University, Wenzhou, China; School of Life Science, Beijing Institute of Technology, Beijing, China
| | - Duanduan Chen
- Wenzhou Safety (Emergency) Institute, Tianjin University, Wenzhou, China; School of Life Science, Beijing Institute of Technology, Beijing, China
| | - Zhiye Li
- Tiantan Neuroimaging Center for Excellence, China National Clinical Research Center for Neurological Diseases, Beijing Tiantan Hospital, Beijing, China
| | - Haojun Fan
- Wenzhou Safety (Emergency) Institute, Tianjin University, Wenzhou, China
| | - Liwei Guo
- Department of Mechanical Engineering, University College London, London, United Kingdom.
| | - Binbin Sui
- Tiantan Neuroimaging Center for Excellence, China National Clinical Research Center for Neurological Diseases, Beijing Tiantan Hospital, Beijing, China.
| | - Yiannis Ventikos
- Department of Mechanical Engineering, University College London, London, United Kingdom; School of Life Science, Beijing Institute of Technology, Beijing, China
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Shariff M, Dobariya A, Albaghdadi O, Awkal J, Moussa H, Reyes G, Syed M, Hart R, Longfellow C, Douglass D, El Ahmadieh TY, Good LB, Jakkamsetti V, Kathote G, Angulo G, Ma Q, Brown R, Dunbar M, Shelton JM, Evers BM, Patnaik S, Hoffmann U, Hackmann AE, Mickey B, Peltz M, Jessen ME, Pascual JM. Maintenance of pig brain function under extracorporeal pulsatile circulatory control (EPCC). Sci Rep 2023; 13:13942. [PMID: 37626089 PMCID: PMC10457326 DOI: 10.1038/s41598-023-39344-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 07/24/2023] [Indexed: 08/27/2023] Open
Abstract
Selective vascular access to the brain is desirable in metabolic tracer, pharmacological and other studies aimed to characterize neural properties in isolation from somatic influences from chest, abdomen or limbs. However, current methods for artificial control of cerebral circulation can abolish pulsatility-dependent vascular signaling or neural network phenomena such as the electrocorticogram even while preserving individual neuronal activity. Thus, we set out to mechanically render cerebral hemodynamics fully regulable to replicate or modify native pig brain perfusion. To this end, blood flow to the head was surgically separated from the systemic circulation and full extracorporeal pulsatile circulatory control (EPCC) was delivered via a modified aorta or brachiocephalic artery. This control relied on a computerized algorithm that maintained, for several hours, blood pressure, flow and pulsatility at near-native values individually measured before EPCC. Continuous electrocorticography and brain depth electrode recordings were used to evaluate brain activity relative to the standard offered by awake human electrocorticography. Under EPCC, this activity remained unaltered or minimally perturbed compared to the native circulation state, as did cerebral oxygenation, pressure, temperature and microscopic structure. Thus, our approach enables the study of neural activity and its circulatory manipulation in independence of most of the rest of the organism.
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Affiliation(s)
- Muhammed Shariff
- The Erik Jonsson School of Engineering and Computer Science, The University of Texas at Dallas, Richardson, TX, 75080, USA
- Rare Brain Disorders Program, Department of Neurology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Mail Code 8813, Dallas, TX, 75390-8813, USA
| | - Aksharkumar Dobariya
- Rare Brain Disorders Program, Department of Neurology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Mail Code 8813, Dallas, TX, 75390-8813, USA
| | - Obada Albaghdadi
- The Erik Jonsson School of Engineering and Computer Science, The University of Texas at Dallas, Richardson, TX, 75080, USA
| | - Jacob Awkal
- The Erik Jonsson School of Engineering and Computer Science, The University of Texas at Dallas, Richardson, TX, 75080, USA
| | - Hadi Moussa
- The Erik Jonsson School of Engineering and Computer Science, The University of Texas at Dallas, Richardson, TX, 75080, USA
| | - Gabriel Reyes
- The Erik Jonsson School of Engineering and Computer Science, The University of Texas at Dallas, Richardson, TX, 75080, USA
| | - Mansur Syed
- The Erik Jonsson School of Engineering and Computer Science, The University of Texas at Dallas, Richardson, TX, 75080, USA
| | - Robert Hart
- The Erik Jonsson School of Engineering and Computer Science, The University of Texas at Dallas, Richardson, TX, 75080, USA
| | - Cameron Longfellow
- Department of Cardiovascular and Thoracic Surgery, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Debra Douglass
- Department of Cardiovascular and Thoracic Surgery, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Tarek Y El Ahmadieh
- Department of Neurological Surgery, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
- Department of Neurosurgery, Loma Linda University Medical Center, Loma Linda, CA, 92354, USA
| | - Levi B Good
- Rare Brain Disorders Program, Department of Neurology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Mail Code 8813, Dallas, TX, 75390-8813, USA
| | - Vikram Jakkamsetti
- Rare Brain Disorders Program, Department of Neurology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Mail Code 8813, Dallas, TX, 75390-8813, USA
| | - Gauri Kathote
- Rare Brain Disorders Program, Department of Neurology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Mail Code 8813, Dallas, TX, 75390-8813, USA
| | - Gus Angulo
- Rare Brain Disorders Program, Department of Neurology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Mail Code 8813, Dallas, TX, 75390-8813, USA
| | - Qian Ma
- Rare Brain Disorders Program, Department of Neurology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Mail Code 8813, Dallas, TX, 75390-8813, USA
| | - Ronnie Brown
- Department of Neurological Surgery, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Misha Dunbar
- Animal Resource Center, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - John M Shelton
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Bret M Evers
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Sourav Patnaik
- Department of Anesthesiology and Pain Management, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Ulrike Hoffmann
- Department of Neurological Surgery, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
- Department of Anesthesiology and Pain Management, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Amy E Hackmann
- Department of Cardiovascular and Thoracic Surgery, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
- Heart and Vascular Center Brigham and Women's Hospital, Boston, MA, 02115, USA
| | - Bruce Mickey
- Department of Neurological Surgery, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Matthias Peltz
- Department of Cardiovascular and Thoracic Surgery, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Michael E Jessen
- Department of Cardiovascular and Thoracic Surgery, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Juan M Pascual
- Rare Brain Disorders Program, Department of Neurology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Mail Code 8813, Dallas, TX, 75390-8813, USA.
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
- Eugene McDermott Center for Human Growth and Development/Center for Human Genetics, The University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
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Terrett LA, McIntyre L, Turgeon AF, English SW. Anemia and Red Blood Cell Transfusion in Aneurysmal Subarachnoid Hemorrhage. Neurocrit Care 2023; 39:91-103. [PMID: 37634181 DOI: 10.1007/s12028-023-01815-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Accepted: 07/13/2023] [Indexed: 08/29/2023]
Abstract
Anemia is very common in aneurysmal subarachnoid hemorrhage (aSAH), with approximately half of the aSAH patient population developing moderate anemia during their hospital stay. The available evidence (both physiologic and clinical) generally supports an association of anemia with unfavorable outcomes. Although aSAH shares a number of common mechanisms of secondary insult with other forms of acute brain injury, aSAH also has specific features that make it unique: an early phase (in which early brain injury predominates) and a delayed phase (in which delayed cerebral ischemia and vasospasm predominate). The effects of both anemia and transfusion are potentially variable between these phases, which may have unique considerations and possibly different risk-benefit profiles. Data on transfusion in this population are almost exclusively limited to observational studies, which suffer from significant heterogeneity and risk of bias. Overall, the results are conflicting, with the balance of the studies suggesting that transfusion is associated with unfavorable outcomes. The transfusion targets that are well established in other critically ill populations should not be automatically applied to patients with aSAH because of the unique disease characteristics of this population and the limited representation of aSAH in the clinical trials that established these targets. There are two upcoming clinical trials evaluating transfusion in aSAH that should help clarify specific transfusion targets. Until then, it is reasonable to base transfusion decisions on the current guidelines and use an individualized approach incorporating physiologic and clinical data when available.
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Affiliation(s)
- Luke A Terrett
- School of Epidemiology and Public Health, University of Ottawa, Ottawa, ON, Canada
- College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
- Department of Adult Critical Care, Saskatchewan Health Authority, Saskatoon, SK, Canada
| | - Lauralyn McIntyre
- Department of Medicine (Critical Care), University of Ottawa, Ottawa, ON, Canada
- Clinical Epidemiology Program (CEP), Ottawa Hospital Research Institute (OHRI), Civic Campus Room F202, 1053 Carling Avenue, Ottawa, ON, K1Y 4E9, Canada
- The Ottawa Hospital, Ottawa, ON, Canada
| | - Alexis F Turgeon
- Department of Anesthesiology and Critical Care Medicine, Université Laval, Quebec City, QC, Canada
- Population Health and Optimal Health Practices Unit, Centre hospitalier universitaire de Québec-Université Laval Research Center, Quebec City, QC, Canada
| | - Shane W English
- Department of Medicine (Critical Care), University of Ottawa, Ottawa, ON, Canada.
- Clinical Epidemiology Program (CEP), Ottawa Hospital Research Institute (OHRI), Civic Campus Room F202, 1053 Carling Avenue, Ottawa, ON, K1Y 4E9, Canada.
- The Ottawa Hospital, Ottawa, ON, Canada.
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12
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Tomoto T, Lu M, Khan AM, Liu J, Pasha EP, Tarumi T, Zhang R. Cerebral blood flow and cerebrovascular resistance across the adult lifespan: A multimodality approach. J Cereb Blood Flow Metab 2023; 43:962-976. [PMID: 36708213 PMCID: PMC10196748 DOI: 10.1177/0271678x231153741] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 12/01/2022] [Accepted: 12/23/2022] [Indexed: 01/29/2023]
Abstract
Cerebral blood flow (CBF) decreases across the adult lifespan; however, more studies are needed to understand the underlying mechanisms. This study measured CBF and cerebrovascular resistance (CVR) using a multimodality approach in 185 healthy adults (21-80 years). Color-coded duplex ultrasonography and phase-contrast MRI were used to measure CBF, CBF velocity, and vessel diameters of the internal carotid (ICA) and vertebral arteries (VA). MRI arterial spin labeling was used to measure brain perfusion. Transcranial Doppler was used to measure CBF velocity at the middle cerebral artery. Structural MRI was used to measure brain volume. CBF was presented as total blood flow (mL/min) and normalized CBF (nCBF, mL/100g/min). Mean arterial pressure was measured to calculate CVR. Age was associated with decreased CBF by ∼3.5 mL/min/year and nCBF by ∼0.19 mL/100g/min/year across the methods. CVR increased by ∼0.011 mmHg/mL/100g/min/year. Blood flow velocities in ICA and VA decreased with age ranging from 0.07-0.15 cm/s/year, while the vessel diameters remained similar among age groups. These findings suggest that age-related decreases in CBF can be attributed mainly to decreases in blood flow velocity in the large cerebral arteries and that increased CVR likely reflects the presence of cerebral vasoconstrictions in the small cerebral arterioles and/or capillaries.
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Affiliation(s)
- Tsubasa Tomoto
- Institute for Exercise and
Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas,
Texas, USA
- Human Informatics and Interaction
Research Institute, National Institute of Advanced Industrial Science and
Technology, Tsukuba, Ibaraki, Japan
- Department of Neurology, University
of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Marilyn Lu
- Department of Neurology, University
of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Ayaz M Khan
- Department of Diagnostic Imaging,
St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Jie Liu
- Department of Pharmacology,
Physiology and Neuroscience, Rutgers University, Newark, New Jersey, USA
| | - Evan P Pasha
- Institute for Exercise and
Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas,
Texas, USA
- Department of Neurology, University
of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Takashi Tarumi
- Institute for Exercise and
Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas,
Texas, USA
- Human Informatics and Interaction
Research Institute, National Institute of Advanced Industrial Science and
Technology, Tsukuba, Ibaraki, Japan
- Department of Neurology, University
of Texas Southwestern Medical Center, Dallas, Texas, USA
- Graduate School of Comprehensive
Human Sciences, University of Tsukuba, Tsukuba, Japan
| | - Rong Zhang
- Institute for Exercise and
Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas,
Texas, USA
- Department of Neurology, University
of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Internal Medicine,
University of Texas Southwestern Medical Center, Dallas, Texas, USA
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13
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Ko YW, Kim SM, Kang KD, Han DH. Changes in Functional Connectivity Between Default Mode Network and Attention Network in Response to Changes in Aerobic Exercise Intensity. Psychiatry Investig 2023; 20:27-34. [PMID: 36721883 PMCID: PMC9890042 DOI: 10.30773/pi.2022.0245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Accepted: 09/29/2022] [Indexed: 01/26/2023] Open
Abstract
OBJECTIVE Aerobic exercise may be associated with changes in brain activity within the default mode network (DMN) and dorsal attention network (DAN). We hypothesized that changes in functional connectivity (FC) within the DMN and DAN might be most effectively activated by moderate-intensity exercise. METHODS Resting-state functional magnetic resonance imaging scans and visuospatial attention tests after resting were performed before and after each of moderate- and high-intensity aerobic exercises (10 min each) in 15 healthy male volunteers. RESULTS The reaction time during the attention test increased significantly, and the rate of correct responses decreased from moderate-intensity exercise condition to high-intensity exercise condition. FC within the DMN under high-intensity exercise condition was higher than that under pre-exercise and moderate-intensity exercise conditions. FC within the DAN under moderate-intensity exercise condition was the highest, whereas FC between the DMN and DAN under moderate-intensity exercise condition was the lowest. Changes in cognitive domain functions were associated with changes in FC between the DMN and DAN. CONCLUSION Our results support the inverted-U hypothesis of maximum arousal efficacy during moderate exercise. Both cognitive domains, namely, the attention system and brain activity domains, may be better under moderate-intensity exercise than under high-intensity exercise.
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Affiliation(s)
- Young-Woo Ko
- Department of Psychiatry, College of Medicine, Chung-Ang University, Seoul, Republic of Korea
| | - Sun Mi Kim
- Department of Psychiatry, College of Medicine, Chung-Ang University, Seoul, Republic of Korea
| | - Kyoung Doo Kang
- Department of Psychiatry, College of Medicine, Chung-Ang University, Seoul, Republic of Korea
| | - Doug Hyun Han
- Department of Psychiatry, College of Medicine, Chung-Ang University, Seoul, Republic of Korea
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14
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The utility of therapeutic hypothermia on cerebral autoregulation. JOURNAL OF INTENSIVE MEDICINE 2022; 3:27-37. [PMID: 36789361 PMCID: PMC9924009 DOI: 10.1016/j.jointm.2022.08.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 07/26/2022] [Accepted: 08/10/2022] [Indexed: 11/07/2022]
Abstract
Cerebral autoregulation (CA) dysfunction is a strong predictor of clinical outcome in patients with acute brain injury (ABI). CA dysfunction is a potential pathologic defect that may lead to secondary injury and worse functional outcomes. Early therapeutic hypothermia (TH) in patients with ABI is controversial. Many factors, including patient selection, timing, treatment depth, duration, and rewarming strategy, impact its clinical efficacy. Therefore, optimizing the benefit of TH is an important issue. This paper reviews the state of current research on the impact of TH on CA function, which may provide the basis and direction for CA-oriented target temperature management.
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15
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Deene YD, Wheatley M, Greig T, Hayes D, Ryder W, Loh H. A multi-modality medical imaging head and neck phantom: Part 1. Design and fabrication. Phys Med 2022; 96:166-178. [DOI: 10.1016/j.ejmp.2022.02.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 02/09/2022] [Indexed: 10/19/2022] Open
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16
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Physiological Function during Exercise and Environmental Stress in Humans-An Integrative View of Body Systems and Homeostasis. Cells 2022; 11:cells11030383. [PMID: 35159193 PMCID: PMC8833916 DOI: 10.3390/cells11030383] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 01/18/2022] [Accepted: 01/19/2022] [Indexed: 11/26/2022] Open
Abstract
Claude Bernard’s milieu intérieur (internal environment) and the associated concept of homeostasis are fundamental to the understanding of the physiological responses to exercise and environmental stress. Maintenance of cellular homeostasis is thought to happen during exercise through the precise matching of cellular energetic demand and supply, and the production and clearance of metabolic by-products. The mind-boggling number of molecular and cellular pathways and the host of tissues and organ systems involved in the processes sustaining locomotion, however, necessitate an integrative examination of the body’s physiological systems. This integrative approach can be used to identify whether function and cellular homeostasis are maintained or compromised during exercise. In this review, we discuss the responses of the human brain, the lungs, the heart, and the skeletal muscles to the varying physiological demands of exercise and environmental stress. Multiple alterations in physiological function and differential homeostatic adjustments occur when people undertake strenuous exercise with and without thermal stress. These adjustments can include: hyperthermia; hyperventilation; cardiovascular strain with restrictions in brain, muscle, skin and visceral organs blood flow; greater reliance on muscle glycogen and cellular metabolism; alterations in neural activity; and, in some conditions, compromised muscle metabolism and aerobic capacity. Oxygen supply to the human brain is also blunted during intense exercise, but global cerebral metabolism and central neural drive are preserved or enhanced. In contrast to the strain seen during severe exercise and environmental stress, a steady state is maintained when humans exercise at intensities and in environmental conditions that require a small fraction of the functional capacity. The impact of exercise and environmental stress upon whole-body functions and homeostasis therefore depends on the functional needs and differs across organ systems.
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17
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Puig O, Henriksen OM, Andersen FL, Lindberg U, Højgaard L, Law I, Ladefoged CN. Deep-learning-based attenuation correction in dynamic [ 15O]H 2O studies using PET/MRI in healthy volunteers. J Cereb Blood Flow Metab 2021; 41:3314-3323. [PMID: 34250821 PMCID: PMC8669198 DOI: 10.1177/0271678x211029178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Quantitative [15O]H2O positron emission tomography (PET) is the accepted reference method for regional cerebral blood flow (rCBF) quantification. To perform reliable quantitative [15O]H2O-PET studies in PET/MRI scanners, MRI-based attenuation-correction (MRAC) is required. Our aim was to compare two MRAC methods (RESOLUTE and DeepUTE) based on ultrashort echo-time with computed tomography-based reference standard AC (CTAC) in dynamic and static [15O]H2O-PET. We compared rCBF from quantitative perfusion maps and activity concentration distribution from static images between AC methods in 25 resting [15O]H2O-PET scans from 14 healthy men at whole-brain, regions of interest and voxel-wise levels. Average whole-brain CBF was 39.9 ± 6.0, 39.0 ± 5.8 and 40.0 ± 5.6 ml/100 g/min for CTAC, RESOLUTE and DeepUTE corrected studies respectively. RESOLUTE underestimated whole-brain CBF by 2.1 ± 1.50% and rCBF in all regions of interest (range -2.4%- -1%) compared to CTAC. DeepUTE showed significant rCBF overestimation only in the occipital lobe (0.6 ± 1.1%). Both MRAC methods showed excellent correlation on rCBF and activity concentration with CTAC, with slopes of linear regression lines between 0.97 and 1.01 and R2 over 0.99. In conclusion, RESOLUTE and DeepUTE provide AC information comparable to CTAC in dynamic [15O]H2O-PET but RESOLUTE is associated with a small but systematic underestimation.
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Affiliation(s)
- Oriol Puig
- Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Otto M Henriksen
- Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Flemming L Andersen
- Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Ulrich Lindberg
- Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Liselotte Højgaard
- Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Ian Law
- Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Claes N Ladefoged
- Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
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18
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Advanced Imaging in the Era of Tissue-Based Treatment for Acute Ischemic Stroke—a Practical Review. Curr Treat Options Neurol 2021. [DOI: 10.1007/s11940-021-00685-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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19
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Abstract
The susceptibility of the brain to ischaemic injury dramatically limits its viability following interruptions in blood flow. However, data from studies of dissociated cells, tissue specimens, isolated organs and whole bodies have brought into question the temporal limits within which the brain is capable of tolerating prolonged circulatory arrest. This Review assesses cell type-specific mechanisms of global cerebral ischaemia, and examines the circumstances in which the brain exhibits heightened resilience to injury. We suggest strategies for expanding such discoveries to fuel translational research into novel cytoprotective therapies, and describe emerging technologies and experimental concepts. By doing so, we propose a new multimodal framework to investigate brain resuscitation following extended periods of circulatory arrest.
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20
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Evaluation of Arterial Spin Labeling MRI-Comparison with 15O-Water PET on an Integrated PET/MR Scanner. Diagnostics (Basel) 2021; 11:diagnostics11050821. [PMID: 34062847 PMCID: PMC8147295 DOI: 10.3390/diagnostics11050821] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 04/28/2021] [Accepted: 04/29/2021] [Indexed: 11/16/2022] Open
Abstract
Cerebral blood flow (CBF) measurements are of high clinical value and can be acquired non-invasively with no radiation exposure using pseudo-continuous arterial spin labeling (ASL). The aim of this study was to evaluate accordance in resting state CBF between ASL (CBFASL) and 15O-water positron emission tomography (PET) (CBFPET) acquired simultaneously on an integrated 3T PET/MR system. The data comprised ASL and dynamic 15O-water PET data with arterial blood sampling of eighteen subjects (eight patients with focal epilepsy and ten healthy controls, age 21 to 61 years). 15O-water PET parametric CBF images were generated using a basis function implementation of the single tissue compartment model. Cortical and subcortical regions were automatically segmented using Freesurfer. Average CBFASL and CBFPET in grey matter were 60 ± 20 and 75 ± 22 mL/100 g/min respectively, with a relatively high correlation (r = 0.78, p < 0.001). Bland-Altman analysis revealed poor agreement (bias = −15 mL/100 g/min, lower and upper limits of agreements = −16 and 45 mL/100 g/min, respectively) with a negative relationship. Accounting for the negative relationship, the width of the limits of agreement could be narrowed from 61 mL/100 g/min to 35 mL/100 g/min using regression-based limits of agreements. Although a high correlation between CBFASL and CBFPET was found, the agreement in absolute CBF values was not sufficient for ASL to be used interchangeably with 15O-water PET.
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21
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See AP, Charbel FT. Bypass for flow-augmentation in atherosclerotic carotid occlusion: a review of the literature and career experience. J Neurosurg Sci 2021; 65:305-321. [PMID: 33709658 DOI: 10.23736/s0390-5616.21.05094-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Atherosclerosis of the internal carotid artery and intracranial vessels can compromise cerebral hemodynamics and cause stroke. Cerebral bypass has a half-century history in augmenting or replacing blood flow the brain. Several trials have investigated various applications of cerebral bypass in flow augmentation for atherosclerotic disease. This review discusses the clinical science of cerebrovascular atherosclerosis to provide the context in which cerebral bypass is currently applied. This includes prior clinical trials, ongoing clinical trials, and consensus guidelines, and is complemented by studies in the physiologic science of cerebrovascular flow. The scientific background is supplemented by the description of the technical art of bypass surgery based on a three-decade experience. Successful application of cerebral bypass to augment flow in atherosclerotic cerebrovascular disease requires correct diagnosis of compromised hemodynamic reserve refractory to medical optimization and an appropriate matching of bypass flow with cerebral demand.
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22
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Saleh MAA, de Lange ECM. Impact of CNS Diseases on Drug Delivery to Brain Extracellular and Intracellular Target Sites in Human: A "WHAT-IF" Simulation Study. Pharmaceutics 2021; 13:95. [PMID: 33451111 PMCID: PMC7828633 DOI: 10.3390/pharmaceutics13010095] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Revised: 01/05/2021] [Accepted: 01/08/2021] [Indexed: 12/23/2022] Open
Abstract
The blood-brain barrier (BBB) is equipped with unique physical and functional processes that control central nervous system (CNS) drug transport and the resulting concentration-time profiles (PK). In CNS diseases, the altered BBB and CNS pathophysiology may affect the CNS PK at the drug target sites in the brain extracellular fluid (brainECF) and intracellular fluid (brainICF) that may result in changes in CNS drug effects. Here, we used our human CNS physiologically-based PK model (LeiCNS-PK3.0) to investigate the impact of altered cerebral blood flow (CBF), tight junction paracellular pore radius (pararadius), brainECF volume, and pH of brainECF (pHECF) and of brainICF (pHICF) on brainECF and brainICF PK for 46 small drugs with distinct physicochemical properties. LeiCNS-PK3.0 simulations showed a drug-dependent effect of the pathophysiological changes on the rate and extent of BBB transport and on brainECF and brainICF PK. Altered pararadius, pHECF, and pHICF affected both the rate and extent of BBB drug transport, whereas changes in CBF and brainECF volume modestly affected the rate of BBB drug transport. While the focus is often on BBB paracellular and active transport processes, this study indicates that also changes in pH should be considered for their important implications on brainECF and brainICF target site PK.
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Affiliation(s)
| | - Elizabeth C. M. de Lange
- Division of Systems Biomedicine and Pharmacology, Leiden Academic Center for Drug Research, Leiden University, 2333 CC Leiden, The Netherlands;
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23
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Beishon L, Clough RH, Kadicheeni M, Chithiramohan T, Panerai RB, Haunton VJ, Minhas JS, Robinson TG. Vascular and haemodynamic issues of brain ageing. Pflugers Arch 2021; 473:735-751. [PMID: 33439324 PMCID: PMC8076154 DOI: 10.1007/s00424-020-02508-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 12/14/2020] [Accepted: 12/16/2020] [Indexed: 01/17/2023]
Abstract
The population is ageing worldwide, thus increasing the burden of common age-related disorders to the individual, society and economy. Cerebrovascular diseases (stroke, dementia) contribute a significant proportion of this burden and are associated with high morbidity and mortality. Thus, understanding and promoting healthy vascular brain ageing are becoming an increasing priority for healthcare systems. In this review, we consider the effects of normal ageing on two major physiological processes responsible for vascular brain function: Cerebral autoregulation (CA) and neurovascular coupling (NVC). CA is the process by which the brain regulates cerebral blood flow (CBF) and protects against falls and surges in cerebral perfusion pressure, which risk hypoxic brain injury and pressure damage, respectively. In contrast, NVC is the process by which CBF is matched to cerebral metabolic activity, ensuring adequate local oxygenation and nutrient delivery for increased neuronal activity. Healthy ageing is associated with a number of key physiological adaptations in these processes to mitigate age-related functional and structural declines. Through multiple different paradigms assessing CA in healthy younger and older humans, generating conflicting findings, carbon dioxide studies in CA have provided the greatest understanding of intrinsic vascular anatomical factors that may mediate healthy ageing responses. In NVC, studies have found mixed results, with reduced, equivalent and increased activation of vascular responses to cognitive stimulation. In summary, vascular and haemodynamic changes occur in response to ageing and are important in distinguishing “normal” ageing from disease states and may help to develop effective therapeutic strategies to promote healthy brain ageing.
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Affiliation(s)
- Lucy Beishon
- Department of Cardiovascular Sciences, University of Leicester, Robert Kilpatrick Clinical Sciences Building, Leicester, LE2 7LX, UK.
| | - Rebecca H Clough
- Department of Cardiovascular Sciences, University of Leicester, Robert Kilpatrick Clinical Sciences Building, Leicester, LE2 7LX, UK
| | - Meeriam Kadicheeni
- Department of Cardiovascular Sciences, University of Leicester, Robert Kilpatrick Clinical Sciences Building, Leicester, LE2 7LX, UK
| | - Tamara Chithiramohan
- Department of Cardiovascular Sciences, University of Leicester, Robert Kilpatrick Clinical Sciences Building, Leicester, LE2 7LX, UK
| | - Ronney B Panerai
- Department of Cardiovascular Sciences, University of Leicester, Robert Kilpatrick Clinical Sciences Building, Leicester, LE2 7LX, UK.,NIHR Leicester Biomedical Research Centre, British Heart Foundation Cardiovascular Research Centre, Glenfield Hospital, Leicester, UK
| | - Victoria J Haunton
- Department of Cardiovascular Sciences, University of Leicester, Robert Kilpatrick Clinical Sciences Building, Leicester, LE2 7LX, UK.,NIHR Leicester Biomedical Research Centre, British Heart Foundation Cardiovascular Research Centre, Glenfield Hospital, Leicester, UK
| | - Jatinder S Minhas
- Department of Cardiovascular Sciences, University of Leicester, Robert Kilpatrick Clinical Sciences Building, Leicester, LE2 7LX, UK.,NIHR Leicester Biomedical Research Centre, British Heart Foundation Cardiovascular Research Centre, Glenfield Hospital, Leicester, UK
| | - Thompson G Robinson
- Department of Cardiovascular Sciences, University of Leicester, Robert Kilpatrick Clinical Sciences Building, Leicester, LE2 7LX, UK.,NIHR Leicester Biomedical Research Centre, British Heart Foundation Cardiovascular Research Centre, Glenfield Hospital, Leicester, UK
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24
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Michna M, Kovarova L, Valerianova A, Malikova H, Weichet J, Malik J. Review of the structural and functional brain changes associated with chronic kidney disease. Physiol Res 2020; 69:1013-1028. [PMID: 33129242 PMCID: PMC8549872 DOI: 10.33549/physiolres.934420] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2019] [Accepted: 08/04/2020] [Indexed: 02/07/2023] Open
Abstract
Chronic kidney disease (CKD) leads to profound metabolic and hemodynamic changes, which damage other organs, such as heart and brain. The brain abnormalities and cognitive deficit progress with the severity of the CKD and are mostly expressed among hemodialysis patients. They have great socio-economic impact. In this review, we present the current knowledge of involved mechanisms.
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Affiliation(s)
- M Michna
- Department of Radiology, University Hospital Kralovske Vinohrady and Third Faculty of Medicine, Charles University, Prague, Czech Republic.
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25
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Brognara F, Felippe ISA, Salgado HC, Paton JFR. Autonomic innervation of the carotid body as a determinant of its sensitivity: implications for cardiovascular physiology and pathology. Cardiovasc Res 2020; 117:1015-1032. [PMID: 32832979 DOI: 10.1093/cvr/cvaa250] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 07/01/2020] [Accepted: 08/18/2020] [Indexed: 12/14/2022] Open
Abstract
The motivation for this review comes from the emerging complexity of the autonomic innervation of the carotid body (CB) and its putative role in regulating chemoreceptor sensitivity. With the carotid bodies as a potential therapeutic target for numerous cardiorespiratory and metabolic diseases, an understanding of the neural control of its circulation is most relevant. Since nerve fibres track blood vessels and receive autonomic innervation, we initiate our review by describing the origins of arterial feed to the CB and its unique vascular architecture and blood flow. Arterial feed(s) vary amongst species and, unequivocally, the arterial blood supply is relatively high to this organ. The vasculature appears to form separate circuits inside the CB with one having arterial venous anastomoses. Both sympathetic and parasympathetic nerves are present with postganglionic neurons located within the CB or close to it in the form of paraganglia. Their role in arterial vascular resistance control is described as is how CB blood flow relates to carotid sinus afferent activity. We discuss non-vascular targets of autonomic nerves, their possible role in controlling glomus cell activity, and how certain transmitters may relate to function. We propose that the autonomic nerves sub-serving the CB provide a rapid mechanism to tune the gain of peripheral chemoreflex sensitivity based on alterations in blood flow and oxygen delivery, and might provide future therapeutic targets. However, there remain a number of unknowns regarding these mechanisms that require further research that is discussed.
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Affiliation(s)
- Fernanda Brognara
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, 85 Park Road, Grafton Auckland 1023, New Zealand.,Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Igor S A Felippe
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, 85 Park Road, Grafton Auckland 1023, New Zealand
| | - Helio C Salgado
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Julian F R Paton
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, 85 Park Road, Grafton Auckland 1023, New Zealand
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26
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Puig O, Henriksen OM, Vestergaard MB, Hansen AE, Andersen FL, Ladefoged CN, Rostrup E, Larsson HB, Lindberg U, Law I. Comparison of simultaneous arterial spin labeling MRI and 15O-H 2O PET measurements of regional cerebral blood flow in rest and altered perfusion states. J Cereb Blood Flow Metab 2020; 40:1621-1633. [PMID: 31500521 PMCID: PMC7370368 DOI: 10.1177/0271678x19874643] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Arterial spin labelling (ASL) is a non-invasive magnetic resonance imaging (MRI) technique that may provide fully quantitative regional cerebral blood flow (rCBF) images. However, before its application in clinical routine, ASL needs to be validated against the clinical gold standard, 15O-H2O positron emission tomography (PET). We aimed to compare the two techniques by performing simultaneous quantitative ASL-MRI and 15O-H2O-PET examinations in a hybrid PET/MRI scanner. Duplicate rCBF measurements were performed in healthy young subjects (n = 14) in rest, during hyperventilation, and after acetazolamide (post-ACZ), yielding 63 combined PET/MRI datasets in total. Average global CBF by ASL-MRI and 15O-H2O-PET was not significantly different in any state (40.0 ± 6.5 and 40.6 ± 4.1 mL/100 g/min, respectively in rest, 24.5 ± 5.1 and 23.4 ± 4.8 mL/100 g/min, respectively, during hyperventilation, and 59.1 ± 10.4 and 64.7 ± 10.0 mL/100 g/min, respectively, post-ACZ). Overall, strong correlation between the two methods was found across all states (slope = 1.01, R2 = 0.82), while the correlations within individual states and of reactivity measures were weaker, in particular in rest (R2 = 0.05, p = 0.03). Regional distribution was similar, although ASL yielded higher perfusion and absolute reactivity in highly vascularized areas. In conclusion, ASL-MRI and 15O-H2O-PET measurements of rCBF are highly correlated across different perfusion states, but with variable correlation within and between hemodynamic states, and systematic differences in regional distribution.
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Affiliation(s)
- Oriol Puig
- Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen, Denmark
| | - Otto M Henriksen
- Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen, Denmark
| | - Mark B Vestergaard
- Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen, Denmark
| | - Adam E Hansen
- Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen, Denmark
| | - Flemming L Andersen
- Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen, Denmark
| | - Claes N Ladefoged
- Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen, Denmark
| | - Egill Rostrup
- Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen, Denmark
| | - Henrik Bw Larsson
- Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen, Denmark
| | - Ulrich Lindberg
- Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen, Denmark
| | - Ian Law
- Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen, Denmark
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Kermorgant M, Nasr N, Czosnyka M, Arvanitis DN, Hélissen O, Senard JM, Pavy-Le Traon A. Impacts of Microgravity Analogs to Spaceflight on Cerebral Autoregulation. Front Physiol 2020; 11:778. [PMID: 32719617 PMCID: PMC7350784 DOI: 10.3389/fphys.2020.00778] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 06/15/2020] [Indexed: 12/16/2022] Open
Abstract
It is well known that exposure to microgravity in astronauts leads to a plethora physiological responses such as headward fluid shift, body unloading, and cardiovascular deconditioning. When astronauts return to Earth, some encounter problems related to orthostatic intolerance. An impaired cerebral autoregulation (CA), which could be compromised by the effects of microgravity, has been proposed as one of the mechanisms responsible for orthostatic intolerance. CA is a homeostatic mechanism that maintains cerebral blood flow for any variations in cerebral perfusion pressure by adapting the vascular tone and cerebral vessel diameter. The ground-based models of microgravity are useful tools for determining the gravitational impact of spaceflight on human body. The head-down tilt bed rest (HDTBR), where the subject remains in supine position at −6 degrees for periods ranging from few days to several weeks is the most commonly used ground-based model of microgravity for cardiovascular deconditioning. head-down bed rest (HDBR) is able to replicate cephalic fluid shift, immobilization, confinement, and inactivity. Dry immersion (DI) model is another approach where the subject remains immersed in thermoneutral water covered with an elastic waterproof fabric separating the subject from the water. Regarding DI, this analog imitates absence of any supporting structure for the body, centralization of body fluids, immobilization and hypokinesia observed during spaceflight. However, little is known about the impact of microgravity on CA. Here, we review the fundamental principles and the different mechanisms involved in CA. We also consider the different approaches in order to assess CA. Finally, we focus on the effects of short- and long-term spaceflight on CA and compare these findings with two specific analogs to microgravity: HDBR and DI.
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Affiliation(s)
- Marc Kermorgant
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France
| | - Nathalie Nasr
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France.,Department of Neurology, Institute for Neurosciences, Toulouse University Hospital, Toulouse, France
| | - Marek Czosnyka
- Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, Cambridge University Hospital, Cambridge, United Kingdom.,Institute of Electronic Systems, Warsaw University of Technology, Warsaw, Poland
| | - Dina N Arvanitis
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France
| | - Ophélie Hélissen
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France
| | - Jean-Michel Senard
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France.,Department of Clinical Pharmacology, Toulouse University Hospital, Toulouse, France
| | - Anne Pavy-Le Traon
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France.,Department of Neurology, Institute for Neurosciences, Toulouse University Hospital, Toulouse, France
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Abstract
People undertaking prolonged vigorous exercise experience substantial bodily fluid losses due to thermoregulatory sweating. If these fluid losses are not replaced, endurance capacity may be impaired in association with a myriad of alterations in physiological function, including hyperthermia, hyperventilation, cardiovascular strain with reductions in brain, skeletal muscle and skin blood perfusion, greater reliance on muscle glycogen and cellular metabolism, alterations in neural activity and, in some conditions, compromised muscle metabolism and aerobic capacity. The physiological strain accompanying progressive exercise-induced dehydration to a level of ~ 4% of body mass loss can be attenuated or even prevented by: (1) ingesting fluids during exercise, (2) exercising in cold environments, and/or (3) working at intensities that require a small fraction of the overall body functional capacity. The impact of dehydration upon physiological function therefore depends on the functional demand evoked by exercise and environmental stress, as cardiac output, limb blood perfusion and muscle metabolism are stable or increase during small muscle mass exercise or resting conditions, but are impaired during whole-body moderate to intense exercise. Progressive dehydration is also associated with an accelerated drop in perfusion and oxygen supply to the human brain during submaximal and maximal endurance exercise. Yet their consequences on aerobic metabolism are greater in the exercising muscles because of the much smaller functional oxygen extraction reserve. This review describes how dehydration differentially impacts physiological function during exercise requiring low compared to high functional demand, with an emphasis on the responses of the human brain, heart and skeletal muscles.
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Puig O, Vestergaard MB, Lindberg U, Hansen AE, Ulrich A, Andersen FL, Johannesen HH, Rostrup E, Law I, Larsson HBW, Henriksen OM. Phase contrast mapping MRI measurements of global cerebral blood flow across different perfusion states - A direct comparison with 15O-H 2O positron emission tomography using a hybrid PET/MR system. J Cereb Blood Flow Metab 2019; 39:2368-2378. [PMID: 30200799 PMCID: PMC6890999 DOI: 10.1177/0271678x18798762] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 05/25/2018] [Accepted: 07/29/2018] [Indexed: 11/29/2022]
Abstract
Phase-contrast mapping (PCM) magnetic resonance imaging (MRI) provides easy-access non-invasive quantification of global cerebral blood flow (gCBF) but its accuracy in altered perfusion states is not established. We aimed to compare paired PCM MRI and 15O-H2O positron emission tomography (PET) measurements of gCBF in different perfusion states in a single scanning session. Duplicate combined gCBF PCM-MRI and 15O-H2O PET measurements were performed in the resting condition, during hyperventilation and after acetazolamide administration (post-ACZ) using a 3T hybrid PET/MR system. A total of 62 paired gCBF measurements were acquired in 14 healthy young male volunteers. Average gCBF in resting state measured by PCM-MRI and 15O-H2O PET were 58.5 ± 10.7 and 38.6 ± 5.7 mL/100 g/min, respectively, during hyperventilation 33 ± 8.6 and 24.7 ± 5.8 mL/100 g/min, respectively, and post-ACZ 89.6 ± 27.1 and 57.3 ± 9.6 mL/100 g/min, respectively. On average, gCBF measured by PCM-MRI was 49% higher compared to 15O-H2O PET. A strong correlation between the two methods across all states was observed (R2 = 0.72, p < 0.001). Bland-Altman analysis suggested a perfusion dependent relative bias resulting in higher relative difference at higher CBF values. In conclusion, measurements of gCBF by PCM-MRI in healthy volunteers show a strong correlation with 15O-H2O PET, but are associated with a large and non-linear perfusion-dependent difference.
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Affiliation(s)
- Oriol Puig
- Department of Clinical Physiology, Nuclear Medicine and PET, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Mark B Vestergaard
- Department of Clinical Physiology, Nuclear Medicine and PET, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Ulrich Lindberg
- Department of Clinical Physiology, Nuclear Medicine and PET, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Adam E Hansen
- Department of Clinical Physiology, Nuclear Medicine and PET, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Annette Ulrich
- Department of Cardiothoracic Anesthesiology, Copenhagen University Hospital Rigshospitalet Blegdamsvej, Copenhagen, Denmark
| | - Flemming L Andersen
- Department of Clinical Physiology, Nuclear Medicine and PET, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Helle H Johannesen
- Department of Clinical Physiology, Nuclear Medicine and PET, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Egill Rostrup
- Department of Clinical Physiology, Nuclear Medicine and PET, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Ian Law
- Department of Clinical Physiology, Nuclear Medicine and PET, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Henrik BW Larsson
- Department of Clinical Physiology, Nuclear Medicine and PET, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Otto M Henriksen
- Department of Clinical Physiology, Nuclear Medicine and PET, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
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Guo L, Li Z, Lyu J, Mei Y, Vardakis JC, Chen D, Han C, Lou X, Ventikos Y. On the Validation of a Multiple-Network Poroelastic Model Using Arterial Spin Labeling MRI Data. Front Comput Neurosci 2019; 13:60. [PMID: 31551742 PMCID: PMC6733888 DOI: 10.3389/fncom.2019.00060] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 08/19/2019] [Indexed: 02/05/2023] Open
Abstract
The Multiple-Network Poroelastic Theory (MPET) is a numerical model to characterize the transport of multiple fluid networks in the brain, which overcomes the problem of conducting separate analyses on individual fluid compartments and losing the interactions between tissue and fluids, in addition to the interaction between the different fluids themselves. In this paper, the blood perfusion results from MPET modeling are partially validated using cerebral blood flow (CBF) data obtained from arterial spin labeling (ASL) magnetic resonance imaging (MRI), which uses arterial blood water as an endogenous tracer to measure CBF. Two subjects—one healthy control and one patient with unilateral middle cerebral artery (MCA) stenosis are included in the validation test. The comparison shows several similarities between CBF data from ASL and blood perfusion results from MPET modeling, such as higher blood perfusion in the gray matter than in the white matter, higher perfusion in the periventricular region for both the healthy control and the patient, and asymmetric distribution of blood perfusion for the patient. Although the partial validation is mainly conducted in a qualitative way, it is one important step toward the full validation of the MPET model, which has the potential to be used as a testing bed for hypotheses and new theories in neuroscience research.
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Affiliation(s)
- Liwei Guo
- Department of Mechanical Engineering, University College London, London, United Kingdom
| | - Zeyan Li
- School of Life Science, Beijing Institute of Technology, Beijing, China
| | - Jinhao Lyu
- Department of Radiology, Chinese PLA General Hospital, Beijing, China
| | - Yuqian Mei
- Department of Computer Science, INSIGNEO Institute, University of Sheffield, Sheffield, United Kingdom
| | - John C Vardakis
- Department of Mechanical Engineering, University College London, London, United Kingdom
| | - Duanduan Chen
- School of Life Science, Beijing Institute of Technology, Beijing, China
| | - Cong Han
- Department of Neurosurgery, The Fifth Medical Centre of PLA General Hospital, Beijing, China
| | - Xin Lou
- Department of Radiology, Chinese PLA General Hospital, Beijing, China
| | - Yiannis Ventikos
- Department of Mechanical Engineering, University College London, London, United Kingdom.,School of Life Science, Beijing Institute of Technology, Beijing, China
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Pascoe MJ, Melzer TR, Horwood LJ, Woodward LJ, Darlow BA. Altered grey matter volume, perfusion and white matter integrity in very low birthweight adults. NEUROIMAGE-CLINICAL 2019; 22:101780. [PMID: 30925384 PMCID: PMC6438988 DOI: 10.1016/j.nicl.2019.101780] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Revised: 03/11/2019] [Accepted: 03/14/2019] [Indexed: 11/26/2022]
Abstract
This study examined the long-term effects of being born very-low-birth-weight (VLBW, <1500 g) on adult cerebral structural development using a multi-method neuroimaging approach. The New Zealand VLBW study cohort comprised 413 individuals born VLBW in 1986. Of the 338 who survived to discharge, 229 were assessed at age 27–29 years. Of these, 150 had a 3 T MRI scan alongside 50 healthy term-born controls. The VLBW group included 53/57 participants born <28 weeks gestation. MRI analyses included: a) structural MRI to assess grey matter (GM) volume and cortical thickness; b) arterial spin labelling (ASL) to quantify GM perfusion; and c) diffusion tensor imaging (DTI) to measure white matter (WM) integrity. Compared to controls, VLBW adults had smaller GM volumes within frontal, temporal, parietal and occipital cortices, bilateral cingulate gyri and left caudate, as well as greater GM volumes in frontal, temporal and occipital areas. Thinner cortex was observed within frontal, temporal and parietal cortices. VLBW adults also had less GM perfusion within limited temporal areas, bilateral hippocampi and thalami. Finally, lower fractional anisotropy (FA) and axial diffusivity (AD) within principal WM tracts was observed in VLBW subjects. Within the VLBW group, birthweight was positively correlated with GM volume and perfusion in cortical and subcortical regions, as well as FA and AD across numerous principal WM tracts. Between group differences within temporal cortices were evident across all imaging modalities, suggesting that the temporal lobe may be particularly susceptible to disruption in development following preterm birth. Overall, findings reveal enduring and pervasive effects of preterm birth on brain structural development, with individuals born at lower birthweights having greater long-term neuropathology. Very-low-birth-weight adults had smaller GM volumes and thinner cortex than controls. VLBW adults also showed regions of larger grey matter volumes and thicker cortex. Several small regions showed lower cerebral perfusion in VLBW adults than in controls. Diffusion tensor MRI suggested poorer WM integrity in VLBW adults than in controls. Within VLBW adults, all MRI measures showed positive associations with birthweight.
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Affiliation(s)
- Maddie J Pascoe
- New Zealand Brain Research Institute, Christchurch 8011, New Zealand.
| | - Tracy R Melzer
- New Zealand Brain Research Institute, Christchurch 8011, New Zealand; Department of Medicine, University of Otago, Christchurch 8011, New Zealand.
| | - L John Horwood
- Department of Psychological Medicine, University of Otago, Christchurch 8011, New Zealand.
| | - Lianne J Woodward
- School of Health Sciences, University of Canterbury, Christchurch 8041, New Zealand.
| | - Brian A Darlow
- Department of Paediatrics, University of Otago, Christchurch 8011, New Zealand.
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33
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Automatic Image-Derived Estimation of the Arterial Whole-Blood Input Function from Dynamic Cerebral PET with $$^{18}$$F-Choline. Artif Intell Med 2019. [DOI: 10.1007/978-3-030-21642-9_43] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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34
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von Bornstädt D, Gertz K, Lagumersindez Denis N, Seners P, Baron JC, Endres M. Sensory stimulation in acute stroke therapy. J Cereb Blood Flow Metab 2018; 38:1682-1689. [PMID: 30073883 PMCID: PMC6168904 DOI: 10.1177/0271678x18791073] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 05/14/2018] [Accepted: 06/17/2018] [Indexed: 02/06/2023]
Abstract
The beneficial effects of cortical activation for functional recovery after ischemic stroke have been well described. However, little is known about the role of early sensory stimulation, i.e. stimulation during first 6 h after stroke onset even during acute treatment. In recent years, various preclinical studies reported significant effects of acute sensory stimulation that range from entire neuroprotection to increased infarct volumes by 30-50%. Systematic knowledge about the effect of acute sensory stimulation on stroke outcome is highly relevant as stroke patients are subject to uncontrolled sensory stimulation during transport, acute treatment, and critical care. This article discusses the current stage of knowledge about acute sensory stimulation and provides directions for future experimental and clinical trials.
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Affiliation(s)
- Daniel von Bornstädt
- Department of Neurology, Charité-Universitätsmedizin Berlin, Berlin, Germany
- Department of Cardiothoracic Surgery, Stanford University School of Medicine, Stanford, CA, USA
- Center for Stroke Research Berlin, Berlin, Germany
| | - Karen Gertz
- Department of Neurology, Charité-Universitätsmedizin Berlin, Berlin, Germany
- Center for Stroke Research Berlin, Berlin, Germany
| | - Nielsen Lagumersindez Denis
- Department of Neurology, Charité-Universitätsmedizin Berlin, Berlin, Germany
- Center for Stroke Research Berlin, Berlin, Germany
| | - Pierre Seners
- Department of Neurology, Hôpital Sainte-Anne, University Paris Descartes, INSERM U894, France
| | - Jean-Claude Baron
- Department of Neurology, Hôpital Sainte-Anne, University Paris Descartes, INSERM U894, France
| | - Matthias Endres
- Department of Neurology, Charité-Universitätsmedizin Berlin, Berlin, Germany
- Center for Stroke Research Berlin, Berlin, Germany
- DZHK (German Center for Cardiovascular Research) Partner Site, Berlin, Germany
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Abstract
Evidence from animal models indicates that lowering temperature by a few degrees can produce substantial neuroprotection. In humans, hypothermia has been found to be neuroprotective with a significant impact on mortality and long-term functional outcome only in cardiac arrest and neonatal hypoxic-ischemic encephalopathy. Clinical trials have explored the potential role of maintaining normothermia and treating fever in critically ill brain injured patients. This review concentrates on basic concepts to understand the physiologic interactions of thermoregulation, effects of thermal modulation in critically ill patients, proposed mechanisms of action of temperature modulation, and practical aspects of targeted temperature management.
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36
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Abstract
Evidence from animal models indicates that lowering temperature by a few degrees can produce substantial neuroprotection. In humans, hypothermia has been found to be neuroprotective with a significant impact on mortality and long-term functional outcome only in cardiac arrest and neonatal hypoxic-ischemic encephalopathy. Clinical trials have explored the potential role of maintaining normothermia and treating fever in critically ill brain injured patients. This review concentrates on basic concepts to understand the physiologic interactions of thermoregulation, effects of thermal modulation in critically ill patients, proposed mechanisms of action of temperature modulation, and practical aspects of targeted temperature management.
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Affiliation(s)
- Fred Rincon
- Division of Critical Care and Neurotrauma, Department of Neurology, Sidney-Kimmel College of Medicine, Thomas Jefferson University, 909 Walnut Street, 3rd Floor, Philadelphia, PA 19107, USA; Division of Critical Care and Neurotrauma, Department of Neurological Surgery, Sidney-Kimmel College of Medicine, Thomas Jefferson University, 909 Walnut Street, 3rd Floor, Philadelphia, PA 19107, USA.
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Components of day-to-day variability of cerebral perfusion measurements - Analysis of phase contrast mapping magnetic resonance imaging measurements in healthy volunteers. PLoS One 2018; 13:e0197807. [PMID: 29879126 PMCID: PMC5991708 DOI: 10.1371/journal.pone.0197807] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Accepted: 05/09/2018] [Indexed: 11/26/2022] Open
Abstract
Purpose The aim of the study was to investigate the components of day-to-day variability of repeated phase contrast mapping (PCM) magnetic resonance imaging measurements of global cerebral blood flow (gCBF). Materials and methods Two dataset were analyzed. In Dataset 1 duplicated PCM measurements of total brain flow were performed in 11 healthy young volunteers on two separate days applying a strictly standardized setup. For comparison PCM measurements obtained from a previously published study (Dataset 2) were analyzed in order to assess long-term variability in an aged population in a less strictly controlled setup. Global CBF was calculated by normalizing total brain flow to brain volume. On each day measurements of hemoglobin, caffeine and glucose were obtained. Linear mixed models were applied to estimate coefficients of variation (CV) of total (CVt), between-subject (CVb), within-subject day-to-day (CVw), and intra-session residual variability (CVr). Results In Dataset 1 CVt, CVb, CVw and CVr were estimated to be 11%, 9.4%, 4% and 4.2%, respectively, and to 8.8%, 7.2%, 2.7% and 4.3%, respectively, when adjusting for hemoglobin and plasma caffeine. In Dataset 2 CVt, CVb and CVw were estimated to be 25.4%, 19.2%, and 15.0%, respectively, and decreased to 16.6%, 8.2% and 12.5%, respectively, when adjusting for the same covariates. Discussion Our results suggest that short-term day-to-day variability of gCBF is relatively low compared to between-subject variability when studied in standardized conditions, whereas long-term variability in an aged population appears to be much larger when studied in less a standardized setup. The results further showed that from 20% to 35% of the total variability in gCBF can be attributed to the effects of hemoglobin and caffeine.
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Kalfaoglu ME, Hızal M, Kiyan A, Gurel K. The effects of chronic smoking on total cerebral blood volume measured by carotid and vertebral artery doppler ultrasonography. JOURNAL OF CLINICAL ULTRASOUND : JCU 2017; 45:561-565. [PMID: 28656716 DOI: 10.1002/jcu.22513] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2016] [Revised: 05/10/2017] [Accepted: 05/31/2017] [Indexed: 06/07/2023]
Abstract
PURPOSE To evaluate the effects of chronic cigarette smoking on total cerebral blood flow in healthy adults by Doppler ultrasonography (US). METHODS We evaluated 50 smoker (median age 29) and 50 nonsmoker (median age 28) healthy, 20- to 40-year-old subjects without any cardiovascular and cerebrovascular disease. Peak systolic maximal blood flow velocity (PSV), end-diastolic maximal blood flow velocity (EDV), time-averaged mean blood flow velocity (TAMV), resistance index (RI), and pulsatility index (PI) were measured in the left and right carotid and vertebral arteries, and total cerebral blood flow volume was calculated. RESULTS There was no significant difference of smoking rate between genders. Blood pressure and PSV values were similar in both groups. EDV values of internal carotid artery (ICA) and vertebral artery (VA) were lower and RI and PI values were higher in smokers. TAMV, total ICA (-10.8%) and VA (-6%) flow volume, and tCBF (-9.2%) were lower in smokers. CONCLUSIONS Doppler US is an effective tool to detect tCBF volume decrease in chronic cigarette smokers. Although minimal, this decrease, as demonstrated here in asymptomatic, healthy people, might be critical in patients with subclinical cerebral arterial insufficiency. © 2017 Wiley Periodicals, Inc. J Clin Ultrasound 45:561-565, 2017.
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Affiliation(s)
| | - Mustafa Hızal
- Department of Radiology, Abant Izzet Baysal University, Izzet Baysal School of Medicine, 14280, Golkoy, Bolu, Turkey
| | - Aysu Kiyan
- Department of Public Health, Abant Izzet Baysal University, Izzet Baysal School of Medicine, 14280, Golkoy, Bolu, Turkey
| | - Kamil Gurel
- Department of Radiology, Abant Izzet Baysal University, Izzet Baysal School of Medicine, 14280, Golkoy, Bolu, Turkey
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Ito H, Mizumoto T, Sawada Y, Fujinaga K, Tempaku H, Yamamoto Y, Tsutsui K, Shimpo H. Neuroprotective effect of pressure-oriented flow regulation and pH-stat management in selective antegrade brain perfusion during total aortic arch repair. Interact Cardiovasc Thorac Surg 2017. [PMID: 28637170 DOI: 10.1093/icvts/ivx182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVES The aim of this study was to assess the safety and effectiveness of our selective antegrade brain perfusion (SABP) strategy, which is characterized by moderate hypothermic and low-pressure management under pH-stat using a completely closed cardiopulmonary bypass circuit with a single centrifugal pump. METHODS Forty-nine consecutive patients (median age, 74) underwent total aortic arch replacement using a 4-branched graft. SABP was conducted with individual cannulation in all arch vessels. The SABP flow rate was monitored, and the flow rates of each arch vessel were also measured in patients with available data. RESULTS One patient died of cerebral infarction, and 7 had transient neurological deficits without apparent findings on postoperative imaging studies and without residual sequels at hospital discharge. The operation, cardiopulmonary bypass, cardiac arrest, circulatory arrest and SABP times were 327 min (interquartile range, 292-381), 211 (184-247), 107 (84.8-138.3), 54.0 (48-68) and 137 (114-158), respectively. The total flow of the SABP was 18.1 ml/kg/min (15.7-20.9). The flow rates of the brachiocephalic, the left carotid and the left subclavian arteries were 9.5 ml/kg/min (7.7-11.5), 4.2 (2.8-5.7) and 4.5 (3.7-5.5), respectively. Only the flow rate of the brachiocephalic artery was significantly correlated with the total SABP flow rate (Spearman rank correlation coefficient, r = 0.58, P < 0.01). CONCLUSIONS The moderate hypothermic, high-flow, low-pressure SABP strategy with pH-stat management can be applied in adult aortic surgery; however, the feasibility and effectiveness of this concept need further evaluation in a prospective controlled study.
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Affiliation(s)
- Hisato Ito
- Department of Cardiothoracic Surgery, Anjo Kosei Hospital, Anjo, Aichi, Japan
| | - Toru Mizumoto
- Department of Cardiothoracic Surgery, Anjo Kosei Hospital, Anjo, Aichi, Japan
| | - Yasuhiro Sawada
- Department of Cardiothoracic Surgery, Anjo Kosei Hospital, Anjo, Aichi, Japan
| | - Kazuya Fujinaga
- Department of Cardiothoracic Surgery, Anjo Kosei Hospital, Anjo, Aichi, Japan
| | - Hironori Tempaku
- Department of Cardiothoracic Surgery, Anjo Kosei Hospital, Anjo, Aichi, Japan
| | - Yasunori Yamamoto
- Department of Cardiothoracic Surgery, Anjo Kosei Hospital, Anjo, Aichi, Japan
| | - Katsuhiro Tsutsui
- Department of Cardiothoracic Surgery, Anjo Kosei Hospital, Anjo, Aichi, Japan
| | - Hideto Shimpo
- Department of Thoracic and Cardiovascular Surgery, Mie University, Tsu, Mie, Japan
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Vestergaard MB, Lindberg U, Aachmann-Andersen NJ, Lisbjerg K, Christensen SJ, Rasmussen P, Olsen NV, Law I, Larsson HBW, Henriksen OM. Comparison of global cerebral blood flow measured by phase-contrast mapping MRI with 15 O-H 2 O positron emission tomography. J Magn Reson Imaging 2016; 45:692-699. [PMID: 27619317 PMCID: PMC5324556 DOI: 10.1002/jmri.25442] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 06/22/2016] [Accepted: 06/22/2016] [Indexed: 11/28/2022] Open
Abstract
Purpose To compare mean global cerebral blood flow (CBF) measured by phase‐contrast mapping magnetic resonance imaging (PCM MRI) and by 15O‐H2O positron emission tomography (PET) in healthy subjects. PCM MRI is increasingly being used to measure mean global CBF, but has not been validated in vivo against an accepted reference technique. Materials and Methods Same‐day measurements of CBF by 15O‐H2O PET and subsequently by PCM MRI were performed on 22 healthy young male volunteers. Global CBF by PET was determined by applying a one‐tissue compartment model with measurement of the arterial input function. Flow was measured in the internal carotid and vertebral arteries by a noncardiac triggered PCM MRI sequence at 3T. The measured flow was normalized to total brain weight determined from a volume‐segmented 3D T1‐weighted anatomical MR‐scan. Results Mean CBF was 34.9 ± 3.4 mL/100 g/min measured by 15O‐H2O PET and 57.0 ± 6.8 mL/100 g/min measured by PCM MRI. The measurements were highly correlated (P = 0.0008, R2 = 0.44), although values obtained by PCM MRI were higher compared to 15O‐H2O PET (absolute and relative differences were 22.0 ± 5.2 mL/100 g/min and 63.4 ± 14.8%, respectively). Conclusion This study confirms the use of PCM MRI for quantification of global CBF, but also that PCM MRI systematically yields higher values relative to 15O‐H2O PET, probably related to methodological bias. Level of Evidence: 3 J. Magn. Reson. Imaging 2017;45:692–699.
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Affiliation(s)
- Mark Bitsch Vestergaard
- Functional Imaging Unit, Department of Clinical Physiology, Nuclear Medicine and PET, Copenhagen University Hospital Rigshospitalet Glostrup, Glostrup, Denmark
| | - Ulrich Lindberg
- Functional Imaging Unit, Department of Clinical Physiology, Nuclear Medicine and PET, Copenhagen University Hospital Rigshospitalet Glostrup, Glostrup, Denmark
| | - Niels Jacob Aachmann-Andersen
- Department of Neuroscience and Pharmacology, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Kristian Lisbjerg
- Department of Neuroscience and Pharmacology, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Søren Just Christensen
- Department of Neuroscience and Pharmacology, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Peter Rasmussen
- Department of Neuroscience and Pharmacology, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Niels Vidiendal Olsen
- Department of Neuroscience and Pharmacology, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Neuroanaesthesia, Neuroscience Centre, Copenhagen University Hospital Rigshospitalet Blegdamsvej, Copenhagen, Denmark
| | - Ian Law
- Institute for Clinical Medicine, The Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Clinical Physiology, Nuclear Medicine and PET, Copenhagen University Hospital Rigshospitalet Blegdamsvej, Copenhagen, Denmark
| | - Henrik Bo Wiberg Larsson
- Functional Imaging Unit, Department of Clinical Physiology, Nuclear Medicine and PET, Copenhagen University Hospital Rigshospitalet Glostrup, Glostrup, Denmark.,Institute for Clinical Medicine, The Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Otto Mølby Henriksen
- Department of Clinical Physiology, Nuclear Medicine and PET, Copenhagen University Hospital Rigshospitalet Blegdamsvej, Copenhagen, Denmark
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41
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Vállez García D, Doorduin J, Willemsen ATM, Dierckx RAJO, Otte A. Altered Regional Cerebral Blood Flow in Chronic Whiplash Associated Disorders. EBioMedicine 2016; 10:249-57. [PMID: 27444853 PMCID: PMC5006659 DOI: 10.1016/j.ebiom.2016.07.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 07/06/2016] [Accepted: 07/07/2016] [Indexed: 01/02/2023] Open
Abstract
There is increasing evidence of central hyperexcitability in chronic whiplash-associated disorders (cWAD). However, little is known about how an apparently simple cervical spine injury can induce changes in cerebral processes. The present study was designed (1) to validate previous results showing alterations of regional cerebral blood flow (rCBF) in cWAD, (2) to test if central hyperexcitability reflects changes in rCBF upon non-painful stimulation of the neck, and (3) to verify our hypothesis that the missing link in understanding the underlying pathophysiology could be the close interaction between the neck and midbrain structures. For this purpose, alterations of rCBF were explored in a case-control study using H215O positron emission tomography, where each group was exposed to four different conditions, including rest and different levels of non-painful electrical stimulation of the neck. rCBF was found to be elevated in patients with cWAD in the posterior cingulate and precuneus, and decreased in the superior temporal, parahippocampal, and inferior frontal gyri, the thalamus and the insular cortex when compared with rCBF in healthy controls. No differences in rCBF were observed between different levels of electrical stimulation. The alterations in regions directly involved with pain perception and interoceptive processing indicate that cWAD symptoms might be the consequence of a mismatch during the integration of information in brain regions involved in pain processing. Differences of rCBF were explored by PET in cWAD patients and healthy volunteers exposed to four conditions. Changes in rCBF were observed in cWAD patients in regions involved in pain perception and interoceptive sensory information. These changes might be the consequence of a mismatch in the integration of interoceptive stimuli in pain processing regions.
In the past, published work on chronic whiplash-associated disorders (cWAD) has caused much confusion and discussion, yet functional imaging methods such as positron emission tomography (PET) have demonstrated a variety of different significant alterations in the perfusion or glucose utilization of the brain. The present study, using PET and the perfusion marker, H215O, is a step forward in whiplash research. It shows changes in perfusion in regions directly involved in pain perception and interoceptive sensory information, such as the insular cortex, precuneus, and posterior cingulate, indicating a mismatch in the integration of interoceptive information in pain processing brain regions.
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Affiliation(s)
- David Vállez García
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Huispostcode EB50, Postbus 30001, 9700 RB Groningen, The Netherlands.
| | - Janine Doorduin
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Huispostcode EB50, Postbus 30001, 9700 RB Groningen, The Netherlands.
| | - Antoon T M Willemsen
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Huispostcode EB50, Postbus 30001, 9700 RB Groningen, The Netherlands.
| | - Rudi A J O Dierckx
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Huispostcode EB50, Postbus 30001, 9700 RB Groningen, The Netherlands.
| | - Andreas Otte
- Division of Biomedical Engineering, Department of Electrical Engineering and Information Technology, Offenburg University, D-77652 Offenburg, Germany.
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42
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Fantini S, Sassaroli A, Tgavalekos KT, Kornbluth J. Cerebral blood flow and autoregulation: current measurement techniques and prospects for noninvasive optical methods. NEUROPHOTONICS 2016; 3:031411. [PMID: 27403447 PMCID: PMC4914489 DOI: 10.1117/1.nph.3.3.031411] [Citation(s) in RCA: 211] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 05/10/2016] [Indexed: 05/23/2023]
Abstract
Cerebral blood flow (CBF) and cerebral autoregulation (CA) are critically important to maintain proper brain perfusion and supply the brain with the necessary oxygen and energy substrates. Adequate brain perfusion is required to support normal brain function, to achieve successful aging, and to navigate acute and chronic medical conditions. We review the general principles of CBF measurements and the current techniques to measure CBF based on direct intravascular measurements, nuclear medicine, X-ray imaging, magnetic resonance imaging, ultrasound techniques, thermal diffusion, and optical methods. We also review techniques for arterial blood pressure measurements as well as theoretical and experimental methods for the assessment of CA, including recent approaches based on optical techniques. The assessment of cerebral perfusion in the clinical practice is also presented. The comprehensive description of principles, methods, and clinical requirements of CBF and CA measurements highlights the potentially important role that noninvasive optical methods can play in the assessment of neurovascular health. In fact, optical techniques have the ability to provide a noninvasive, quantitative, and continuous monitor of CBF and autoregulation.
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Affiliation(s)
- Sergio Fantini
- Tufts University, Department of Biomedical Engineering, 4 Colby Street, Medford, Massachusetts 02155, United States
| | - Angelo Sassaroli
- Tufts University, Department of Biomedical Engineering, 4 Colby Street, Medford, Massachusetts 02155, United States
| | - Kristen T. Tgavalekos
- Tufts University, Department of Biomedical Engineering, 4 Colby Street, Medford, Massachusetts 02155, United States
| | - Joshua Kornbluth
- Tufts University School of Medicine, Department of Neurology, Division of Neurocritical Care, 800 Washington Street, Box #314, Boston, Massachusetts 02111, United States
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43
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Rooijackers HMM, Wiegers EC, Tack CJ, van der Graaf M, de Galan BE. Brain glucose metabolism during hypoglycemia in type 1 diabetes: insights from functional and metabolic neuroimaging studies. Cell Mol Life Sci 2016; 73:705-22. [PMID: 26521082 PMCID: PMC4735263 DOI: 10.1007/s00018-015-2079-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 10/16/2015] [Accepted: 10/20/2015] [Indexed: 12/30/2022]
Abstract
Hypoglycemia is the most frequent complication of insulin therapy in patients with type 1 diabetes. Since the brain is reliant on circulating glucose as its main source of energy, hypoglycemia poses a threat for normal brain function. Paradoxically, although hypoglycemia commonly induces immediate decline in cognitive function, long-lasting changes in brain structure and cognitive function are uncommon in patients with type 1 diabetes. In fact, recurrent hypoglycemia initiates a process of habituation that suppresses hormonal responses to and impairs awareness of subsequent hypoglycemia, which has been attributed to adaptations in the brain. These observations sparked great scientific interest into the brain's handling of glucose during (recurrent) hypoglycemia. Various neuroimaging techniques have been employed to study brain (glucose) metabolism, including PET, fMRI, MRS and ASL. This review discusses what is currently known about cerebral metabolism during hypoglycemia, and how findings obtained by functional and metabolic neuroimaging techniques contributed to this knowledge.
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Affiliation(s)
- Hanne M M Rooijackers
- Department of Internal Medicine 463, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands.
| | - Evita C Wiegers
- Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Cees J Tack
- Department of Internal Medicine 463, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - Marinette van der Graaf
- Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
- Department of Pediatrics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Bastiaan E de Galan
- Department of Internal Medicine 463, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
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44
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Park CS, Payne SJ. Modelling the effects of cerebral microvasculature morphology on oxygen transport. Med Eng Phys 2016; 38:41-7. [PMID: 26499366 PMCID: PMC4751405 DOI: 10.1016/j.medengphy.2015.09.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 07/29/2015] [Accepted: 09/10/2015] [Indexed: 12/28/2022]
Abstract
The cerebral microvasculature plays a vital role in adequately supplying blood to the brain. Determining the health of the cerebral microvasculature is important during pathological conditions, such as stroke and dementia. Recent studies have shown the complex relationship between cerebral metabolic rate and transit time distribution, the transit times of all the possible pathways available dependent on network topology. In this paper, we extend a recently developed technique to solve for residue function, the amount of tracer left in the vasculature at any time, and transit time distribution in an existing model of the cerebral microvasculature to calculate cerebral metabolism. We present the mathematical theory needed to solve for oxygen concentration followed by results of the simulations. It is found that oxygen extraction fraction, the fraction of oxygen removed from the blood in the capillary network by the tissue, and cerebral metabolic rate are dependent on both mean and heterogeneity of the transit time distribution. For changes in cerebral blood flow, a positive correlation can be observed between mean transit time and oxygen extraction fraction, and a negative correlation between mean transit time and metabolic rate of oxygen. A negative correlation can also be observed between transit time heterogeneity and the metabolic rate of oxygen for a constant cerebral blood flow. A sensitivity analysis on the mean and heterogeneity of the transit time distribution was able to quantify their respective contributions to oxygen extraction fraction and metabolic rate of oxygen. Mean transit time has a greater contribution than the heterogeneity for oxygen extraction fraction. This is found to be opposite for metabolic rate of oxygen. These results provide information on the role of the cerebral microvasculature and its effects on flow and metabolism. They thus open up the possibility of obtaining additional valuable clinical information for diagnosing and treating cerebrovascular diseases.
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Affiliation(s)
- Chang Sub Park
- Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, United Kingdom.
| | - Stephen J Payne
- Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, United Kingdom
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45
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Acute ischemic stroke imaging: a practical approach for diagnosis and triage. Int J Cardiovasc Imaging 2015; 32:19-33. [DOI: 10.1007/s10554-015-0757-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 08/26/2015] [Indexed: 11/30/2022]
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46
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Carbon dioxide induced changes in cerebral blood flow and flow velocity: role of cerebrovascular resistance and effective cerebral perfusion pressure. J Cereb Blood Flow Metab 2015; 35:1470-7. [PMID: 25873428 PMCID: PMC4640336 DOI: 10.1038/jcbfm.2015.63] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Revised: 02/17/2015] [Accepted: 03/12/2015] [Indexed: 11/08/2022]
Abstract
In addition to cerebrovascular resistance (CVR) zero flow pressure (ZFP), effective cerebral perfusion pressure (CPPe) and the resistance area product (RAP) are supplemental determinants of cerebral blood flow (CBF). Until now, the interrelationship of PaCO2-induced changes in CBF, CVR, CPPe, ZFP, and RAP is not fully understood. In a controlled crossover trial, we investigated 10 anesthetized patients aiming at PaCO2 levels of 30, 37, 43, and 50 mm Hg. Cerebral blood flow was measured with a modified Kety-Schmidt-technique. Zero flow pressure and RAP was estimated by linear regression analysis of pressure-flow velocity relationships of the middle cerebral artery. Effective cerebral perfusion pressure was calculated as the difference between mean arterial pressure and ZFP, CVR as the ratio CPPe/CBF. Statistical analysis was performed by one-way RM-ANOVA. When comparing hypocapnia with hypercapnia, CBF showed a significant exponential reduction by 55% and mean VMCA by 41%. Effective cerebral perfusion pressure linearly decreased by 17% while ZFP increased from 14 to 29 mm Hg. Cerebrovascular resistance increased by 96% and RAP by 39%; despite these concordant changes in mean CVR and Doppler-derived RAP correlation between these variables was weak (r=0.43). In conclusion, under general anesthesia hypocapnia-induced reduction in CBF is caused by both an increase in CVR and a decrease in CPPe, as a consequence of an increase in ZFP.
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47
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Vachha BA, Schaefer PW. Imaging Patterns and Management Algorithms in Acute Stroke: An Update for the Emergency Radiologist. Radiol Clin North Am 2015; 53:801-26, ix. [PMID: 26046512 DOI: 10.1016/j.rcl.2015.02.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Neuroimaging plays a key role in the initial work-up of patients with symptoms of acute stroke. Understanding the advantages and limitations of available CT and MR imaging techniques and how to use them optimally in the emergency setting is crucial for accurately making the diagnosis of acute stroke and for rapidly determining appropriate treatment.
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Affiliation(s)
- Behroze A Vachha
- Neuroradiology, Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, Boston, MA 02114, USA
| | - Pamela W Schaefer
- Neuroradiology, Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, Boston, MA 02114, USA.
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48
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Stewart SB, Koller JM, Campbell MC, Perlmutter JS, Black KJ. Additive global cerebral blood flow normalization in arterial spin labeling perfusion imaging. PeerJ 2015; 3:e834. [PMID: 25802806 PMCID: PMC4369335 DOI: 10.7717/peerj.834] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Accepted: 02/20/2015] [Indexed: 11/20/2022] Open
Abstract
To determine how different methods of normalizing for global cerebral blood flow (gCBF) affect image quality and sensitivity to cortical activation, pulsed arterial spin labeling (pASL) scans obtained during a visual task were normalized by either additive or multiplicative normalization of modal gCBF. Normalization by either method increased the statistical significance of cortical activation by a visual stimulus. However, image quality was superior with additive normalization, whether judged by intensity histograms or by reduced variability within gray and white matter.
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Affiliation(s)
- Stephanie B Stewart
- Department of Neurology, Washington University School of Medicine , St Louis, MO , USA ; Department of Psychiatry, Washington University School of Medicine , St Louis, MO , USA
| | - Jonathan M Koller
- Department of Psychiatry, Washington University School of Medicine , St Louis, MO , USA
| | - Meghan C Campbell
- Department of Neurology, Washington University School of Medicine , St Louis, MO , USA ; Department of Radiology, Washington University School of Medicine , St Louis, MO , USA
| | - Joel S Perlmutter
- Department of Neurology, Washington University School of Medicine , St Louis, MO , USA ; Department of Radiology, Washington University School of Medicine , St Louis, MO , USA ; Departments of Anatomy and Neurobiology, Washington University School of Medicine , St Louis, MO , USA ; Division of Biology and Biomedical Sciences, Washington University School of Medicine , St Louis, MO , USA ; Programs in Physical Therapy and Occupational Therapy, Washington University School of Medicine , St Louis, MO , USA
| | - Kevin J Black
- Department of Neurology, Washington University School of Medicine , St Louis, MO , USA ; Department of Psychiatry, Washington University School of Medicine , St Louis, MO , USA ; Department of Radiology, Washington University School of Medicine , St Louis, MO , USA ; Departments of Anatomy and Neurobiology, Washington University School of Medicine , St Louis, MO , USA ; Division of Biology and Biomedical Sciences, Washington University School of Medicine , St Louis, MO , USA
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49
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Functional mapping of the human visual cortex with intravoxel incoherent motion MRI. PLoS One 2015; 10:e0117706. [PMID: 25647423 PMCID: PMC4315413 DOI: 10.1371/journal.pone.0117706] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Accepted: 12/30/2014] [Indexed: 01/01/2023] Open
Abstract
Functional imaging with intravoxel incoherent motion (IVIM) magnetic resonance imaging (MRI) is demonstrated. Images were acquired at 3 Tesla using a standard Stejskal-Tanner diffusion-weighted echo-planar imaging sequence with multiple b-values. Cerebro-spinal fluid signal, which is highly incoherent, was suppressed with an inversion recovery preparation pulse. IVIM microvascular perfusion parameters were calculated according to a two-compartment (vascular and non-vascular) diffusion model. The results obtained in 8 healthy human volunteers during visual stimulation are presented. The IVIM blood flow related parameter fD* increased 170% during stimulation in the visual cortex, and 70% in the underlying white matter.
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50
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Nybo L, Rasmussen P, Sawka MN. Performance in the heat-physiological factors of importance for hyperthermia-induced fatigue. Compr Physiol 2014; 4:657-89. [PMID: 24715563 DOI: 10.1002/cphy.c130012] [Citation(s) in RCA: 201] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
This article presents a historical overview and an up-to-date review of hyperthermia-induced fatigue during exercise in the heat. Exercise in the heat is associated with a thermoregulatory burden which mediates cardiovascular challenges and influence the cerebral function, increase the pulmonary ventilation, and alter muscle metabolism; which all potentially may contribute to fatigue and impair the ability to sustain power output during aerobic exercise. For maximal intensity exercise, the performance impairment is clearly influenced by cardiovascular limitations to simultaneously support thermoregulation and oxygen delivery to the active skeletal muscle. In contrast, during submaximal intensity exercise at a fixed intensity, muscle blood flow and oxygen consumption remain unchanged and the potential influence from cardiovascular stressing and/or high skin temperature is not related to decreased oxygen delivery to the skeletal muscles. Regardless, performance is markedly deteriorated and exercise-induced hyperthermia is associated with central fatigue as indicated by impaired ability to sustain maximal muscle activation during sustained contractions. The central fatigue appears to be influenced by neurotransmitter activity of the dopaminergic system, but inhibitory signals from thermoreceptors arising secondary to the elevated core, muscle and skin temperatures and augmented afferent feedback from the increased ventilation and the cardiovascular stressing (perhaps baroreceptor sensing of blood pressure stability) and metabolic alterations within the skeletal muscles are likely all factors of importance for afferent feedback to mediate hyperthermia-induced fatigue during submaximal intensity exercise. Taking all the potential factors into account, we propose an integrative model that may help understanding the interplay among factors, but also acknowledging that the influence from a given factor depends on the exercise hyperthermia situation.
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Affiliation(s)
- Lars Nybo
- Department of Nutrition, Exercise and Sport Sciences, University of Copenhagen, Denmark
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