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Nippert AR, Chiang PP, Newman EA. Whisker-evoked neurovascular coupling is preserved during hypoglycemia in mouse cortical arterioles and capillaries. J Cereb Blood Flow Metab 2024; 44:155-168. [PMID: 37728791 PMCID: PMC10993878 DOI: 10.1177/0271678x231201241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 07/12/2023] [Accepted: 08/15/2023] [Indexed: 09/21/2023]
Abstract
Hypoglycemia is a serious complication of insulin treatment of diabetes that can lead to coma and death. Neurovascular coupling, which mediates increased local blood flow in response to neuronal activity, increases glucose availability to active neurons. This mechanism could be essential for neuronal health during hypoglycemia, when total glucose supplies are low. Previous studies suggest, however, that neurovascular coupling (a transient blood flow increase in response to an increase in neuronal activity) may be reduced during hypoglycemia. Such a reduction in blood flow increase would exacerbate the effects of hypoglycemia, depriving active neurons of glucose. We have reexamined the effects of hypoglycemia on neurovascular coupling by simultaneously monitoring neuronal and vascular responses to whisker stimulation in the awake mouse somatosensory cortex. We find that neurovascular coupling at both penetrating arterioles and at 2nd order capillaries did not change significantly during insulin-induced hypoglycemia compared to euglycemia. In addition, we show that the basal diameter of both arterioles and capillaries increases during hypoglycemia (10.3 and 9.7% increases, respectively). Our results demonstrate that both neurovascular coupling and basal increases in vessel diameter are active mechanisms which help to maintain an adequate supply of glucose to the brain during hypoglycemia.
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Affiliation(s)
| | | | - Eric A Newman
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota, USA
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2
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Cufe J, Gierse F, Schäfers KP, Hermann S, Schäfers MA, Backhaus P, Büther F. Dispersion-corrected extracorporeal arterial input functions in PET studies of mice: a comparison to intracorporeal microprobe measurements. EJNMMI Res 2023; 13:86. [PMID: 37752319 PMCID: PMC10522560 DOI: 10.1186/s13550-023-01031-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 09/08/2023] [Indexed: 09/28/2023] Open
Abstract
BACKGROUND Kinetic modelling of dynamic PET typically requires knowledge of the arterial radiotracer concentration (arterial input function, AIF). Its accurate determination is very difficult in mice. AIF measurements in an extracorporeal shunt can be performed; however, this introduces catheter dispersion. We propose a framework for extracorporeal dispersion correction and validated it by comparison to invasively determined intracorporeal AIFs using implanted microprobes. RESULTS The response of an extracorporeal radiation detector to radioactivity boxcar functions, characterised by a convolution-based dispersion model, gave best fits using double-gamma variate and single-gamma variate kernels compared to mono-exponential kernels for the investigated range of flow rates. Parametric deconvolution with the optimal kernels was performed on 9 mice that were injected with a bolus of 39 ± 25 MBq [18F]F-PSMA-1007 after application of an extracorporeal circulation for three different flow rates in order to correct for dispersion. Comparison with synchronous implantation of microprobes for invasive aortic AIF recordings showed favourable correspondence, with no significant difference in terms of area-under-curve after 300 s and 5000 s. One-tissue and two-tissue compartment model simulations were performed to investigate differences in kinetic parameters between intra- and extracorporeally measured AIFs. Results of the modelling study revealed kinetic parameters close to the chosen simulated values in all compartment models. CONCLUSION The high correspondence of simultaneously intra- and extracorporeally determined AIFs and resulting model parameters establishes a feasible framework for extracorporeal dispersion correction. This should allow more precise and accurate kinetic modelling in small animal experiments.
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Affiliation(s)
- Juela Cufe
- Department of Nuclear Medicine, University Hospital Münster, Albert-Schweitzer-Campus 1, 48149, Münster, Germany.
- European Institute for Molecular Imaging (EIMI), University of Münster, Münster, Germany.
| | - Florian Gierse
- European Institute for Molecular Imaging (EIMI), University of Münster, Münster, Germany
| | - Klaus P Schäfers
- European Institute for Molecular Imaging (EIMI), University of Münster, Münster, Germany
| | - Sven Hermann
- European Institute for Molecular Imaging (EIMI), University of Münster, Münster, Germany
| | - Michael A Schäfers
- Department of Nuclear Medicine, University Hospital Münster, Albert-Schweitzer-Campus 1, 48149, Münster, Germany
- European Institute for Molecular Imaging (EIMI), University of Münster, Münster, Germany
| | - Philipp Backhaus
- Department of Nuclear Medicine, University Hospital Münster, Albert-Schweitzer-Campus 1, 48149, Münster, Germany
- European Institute for Molecular Imaging (EIMI), University of Münster, Münster, Germany
| | - Florian Büther
- Department of Nuclear Medicine, University Hospital Münster, Albert-Schweitzer-Campus 1, 48149, Münster, Germany
- European Institute for Molecular Imaging (EIMI), University of Münster, Münster, Germany
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3
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Göttler J, Preibisch C, Riederer I, Pasquini L, Alexopoulos P, Bohn KP, Yakushev I, Beller E, Kaczmarz S, Zimmer C, Grimmer T, Drzezga A, Sorg C. Reduced blood oxygenation level dependent connectivity is related to hypoperfusion in Alzheimer's disease. J Cereb Blood Flow Metab 2019; 39:1314-1325. [PMID: 29431005 PMCID: PMC6668525 DOI: 10.1177/0271678x18759182] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Functional connectivity of blood oxygenation level dependent signal fluctuations (BOLD-FC) is decreased in Alzheimer's disease (AD), and suggested to reflect reduced coherence in neural population activity; however, as both neuronal and vascular-hemodynamic processes underlie BOLD signals, impaired perfusion might also contribute to reduced BOLD-FC; 42 AD patients and 27 controls underwent simultaneous PET/MR imaging. Resting-state functional MRI assessed BOLD co-activity to quantify BOLD-FC, pulsed arterial spin labeling (pASL) assessed cerebral blood flow (CBF) as proxy for vascular hemodynamics, and 18F-fluorodeoxyglucose PET assessed glucose metabolism (GluMet) to index neuronal activity. Patients' BOLD-FC, CBF, and GluMet were reduced within the same precuneal parietal regions. BOLD-FC was positively associated with mean CBF, specifically in patients and controlled for GluMet levels, suggesting that BOLD-FC reductions correlate with pASL-derived hypoperfusion in AD, independently from 18F-fluorodeoxyglucose PET-derived hypometabolism. Data indicate that impaired vascular hemodynamic processes contribute to reduced BOLD connectivity in AD.
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Affiliation(s)
- Jens Göttler
- 1 Department of Diagnostic and Interventional Neuroradiology, Klinikum Rechts der Isar, Technische Universität München, Munich, Germany.,2 TUM Neuroimaging Center (TUM-NIC), Klinikum Rechts der Isar, Technische Universität München, Munich, Germany
| | - Christine Preibisch
- 1 Department of Diagnostic and Interventional Neuroradiology, Klinikum Rechts der Isar, Technische Universität München, Munich, Germany.,2 TUM Neuroimaging Center (TUM-NIC), Klinikum Rechts der Isar, Technische Universität München, Munich, Germany.,3 Clinic for Neurology, Klinikum Rechts der Isar, Technische Universität München, Munich, Germany
| | - Isabelle Riederer
- 1 Department of Diagnostic and Interventional Neuroradiology, Klinikum Rechts der Isar, Technische Universität München, Munich, Germany.,2 TUM Neuroimaging Center (TUM-NIC), Klinikum Rechts der Isar, Technische Universität München, Munich, Germany
| | - Lorenzo Pasquini
- 2 TUM Neuroimaging Center (TUM-NIC), Klinikum Rechts der Isar, Technische Universität München, Munich, Germany.,4 Department of Neurology, Memory and Aging Center, University of California San Francisco, San Francisco, CA, USA
| | - Panagiotis Alexopoulos
- 5 Department of Psychiatry and Psychotherapy, Klinikum Rechts der Isar, Technische Universität München, Munich, Germany
| | - Karl Peter Bohn
- 6 Department of Nuclear Medicine, Klinikum Rechts der Isar, Technische Universität München, Munich, Germany
| | - Igor Yakushev
- 2 TUM Neuroimaging Center (TUM-NIC), Klinikum Rechts der Isar, Technische Universität München, Munich, Germany.,6 Department of Nuclear Medicine, Klinikum Rechts der Isar, Technische Universität München, Munich, Germany
| | - Ebba Beller
- 7 Department of Radiology, Klinikum Großhadern, Ludwig-Maximilans-Universität München, Munich, Germany
| | - Stephan Kaczmarz
- 1 Department of Diagnostic and Interventional Neuroradiology, Klinikum Rechts der Isar, Technische Universität München, Munich, Germany.,2 TUM Neuroimaging Center (TUM-NIC), Klinikum Rechts der Isar, Technische Universität München, Munich, Germany
| | - Claus Zimmer
- 1 Department of Diagnostic and Interventional Neuroradiology, Klinikum Rechts der Isar, Technische Universität München, Munich, Germany
| | - Timo Grimmer
- 2 TUM Neuroimaging Center (TUM-NIC), Klinikum Rechts der Isar, Technische Universität München, Munich, Germany.,5 Department of Psychiatry and Psychotherapy, Klinikum Rechts der Isar, Technische Universität München, Munich, Germany
| | - Alexander Drzezga
- 6 Department of Nuclear Medicine, Klinikum Rechts der Isar, Technische Universität München, Munich, Germany.,8 Department of Nuclear Medicine, University of Cologne, Cologne, Germany
| | - Christian Sorg
- 1 Department of Diagnostic and Interventional Neuroradiology, Klinikum Rechts der Isar, Technische Universität München, Munich, Germany.,2 TUM Neuroimaging Center (TUM-NIC), Klinikum Rechts der Isar, Technische Universität München, Munich, Germany.,5 Department of Psychiatry and Psychotherapy, Klinikum Rechts der Isar, Technische Universität München, Munich, Germany
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Yang J, Zhang LJ, Wang F, Hong T, Liu Z. Molecular imaging of diabetes and diabetic complications: Beyond pancreatic β-cell targeting. Adv Drug Deliv Rev 2019; 139:32-50. [PMID: 30529307 DOI: 10.1016/j.addr.2018.11.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 09/28/2018] [Accepted: 11/27/2018] [Indexed: 12/13/2022]
Abstract
Diabetes is a chronic non-communicable disease affecting over 400 million people worldwide. Diabetic patients are at a high risk of various complications, such as cardiovascular, renal, and other diseases. The pathogenesis of diabetes (both type 1 and type 2 diabetes) is associated with a functional impairment of pancreatic β-cells. Consequently, most efforts to manage and prevent diabetes have focused on preserving β-cells and their function. Advances in imaging techniques, such as magnetic resonance imaging, magnetic resonance spectroscopy, positron emission tomography, and single-photon-emission computed tomography, have enabled noninvasive and quantitative detection and characterization of the population and function of β-cells in vivo. These advantages aid in defining and monitoring the progress of diabetes and determining the efficacy of anti-diabetic therapies. Beyond β-cell targeting, molecular imaging of biomarkers associated with the development of diabetes, e.g., lymphocyte infiltration, insulitis, and metabolic changes, may also be a promising strategy for early detection of diabetes, monitoring its progression, and occurrence of complications, as well as facilitating exploration of new therapeutic interventions. Moreover, molecular imaging of glucose uptake, production and excretion in specified tissues is critical for understanding the pathogenesis of diabetes. In the current review, we summarize and discuss recent advances in noninvasive imaging technologies for imaging of biomarkers beyond β-cells for early diagnosis of diabetes, investigation of glucose metabolism, and precise diagnosis and monitoring of diabetic complications for better management of diabetic patients.
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Affiliation(s)
- Jichun Yang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences Peking University Health Science Center, Key Laboratory of Cardiovascular Science of the Ministry of Education, Center for Non-coding RNA Medicine, Beijing 100191, China.
| | - Long Jiang Zhang
- Department of Medical Imaging, Jinling Hospital, Medical School of Nanjing University, Nanjing, Jiangsu 210002, China
| | - Fan Wang
- Medical Isotopes Research Center and Department of Radiation Medicine, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Tianpei Hong
- Department of Endocrinology and Metabolism, Peking University Third Hospital, Beijing 100191, China.
| | - Zhaofei Liu
- Medical Isotopes Research Center and Department of Radiation Medicine, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China.
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Narchi H, Thachillath P, Souid AK. Forebrain cellular bioenergetics in neonatal mice. J Neonatal Perinatal Med 2018; 11:79-86. [PMID: 29689747 DOI: 10.3233/npm-181737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Hypoglycemia occurs frequently in the neonate and may result in neurologic dysfunction. Its impact on the kinetics of cellular respiration and bioenergetics in the neonatal brain remains to be explored. AIMS Develop murine model to investigate the effects of hypoglycemia on neonatal brain bioenergetics. STUDY DESIGN Forebrain fragments were excised from euthanized BALB/c pups aged <24 hours to 14 days. We measured cellular respiration (μM O2 min-1.mg-1) in phosphate-buffered saline with and without glucose, using phosphorescence oxygen analyzer, as well as cellular adenosine triphosphate (ATP, nmol.mg-1) using the luciferin-luciferase system. RESULTS In the presence of glucose, although cellular respiration was 11% lower in pups ≤3 days compared to those 3- 14 days old (0.48 vs. 0.54), that difference was not statistically significant (p = 0.14). Respiration driven by endogenous metabolic fuels (without added glucose) was 16% lower in pups ≤3 days compared to those 3- 14 days (0.35 vs. 0.42, p = 0.03), confirming their increased dependency on exogenous glucose. Although cellular ATP was similar between the two age groups (14.9 vs. 11.2, p = 0.32), the ATP content was more severely depleted without added glucose in the younger pups, especially in the presence of the cytochrome c oxidase inhibitor cyanide. The first-order rate constant of cellular ATP decay (hydrolysis) was 44% lower in 2-day-old pups compared to 14-day-old mice (0.43 vs. 0.77 min-1, p = 0.03). CONCLUSIONS Forebrain cellular respiration and ATP consumption are lower in young pups than older mice. In the absence of glucose, the support for these processes is reduced in young pups, explaining their brain hypersensitivity to hypoglycemia.
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Affiliation(s)
- Hassib Narchi
- Department of Pediatrics, College of Medicine and Health Sciences, United Arab Emirates University, United Arab Emirates
| | - Pramathan Thachillath
- Department of Pediatrics, College of Medicine and Health Sciences, United Arab Emirates University, United Arab Emirates
| | - Abdul-Kader Souid
- Department of Pediatrics, College of Medicine and Health Sciences, United Arab Emirates University, United Arab Emirates
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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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7
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Vanhove C, Bankstahl JP, Krämer SD, Visser E, Belcari N, Vandenberghe S. Accurate molecular imaging of small animals taking into account animal models, handling, anaesthesia, quality control and imaging system performance. EJNMMI Phys 2015; 2:31. [PMID: 26560138 PMCID: PMC4642455 DOI: 10.1186/s40658-015-0135-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 11/05/2015] [Indexed: 11/22/2022] Open
Abstract
Small-animal imaging has become an important technique for the development of new radiotracers, drugs and therapies. Many laboratories have now a combination of different small-animal imaging systems, which are being used by biologists, pharmacists, medical doctors and physicists. The aim of this paper is to give an overview of the important factors in the design of a small animal, nuclear medicine and imaging experiment. Different experts summarize one specific aspect important for a good design of a small-animal experiment.
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Affiliation(s)
- Christian Vanhove
- Department of Electronics and Information Systems, MEDISIP, Ghent University-iMinds Medical IT-IBiTech, De Pintelaan 185 block B, B-9000, Ghent, Belgium.
| | - Jens P Bankstahl
- Department of Nuclear Medicine, Preclinical Molecular Imaging, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany
| | - Stefanie D Krämer
- Radiopharmaceutical Sciences/Biopharmacy, ETH Zurich, Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, Vladimir-Prelog-Weg 4, CH-8093, Zurich, Switzerland
| | - Eric Visser
- Department of Radiology and Nuclear Medicine, Radboudumc, 6525 GA Nijmegen, the Netherlands
| | - Nicola Belcari
- Department of Physics, University of Pisa and INFN sezione di Pisa, 56127 Pisa, Italy
| | - Stefaan Vandenberghe
- Department of Electronics and Information Systems, MEDISIP, Ghent University-iMinds Medical IT-IBiTech, De Pintelaan 185 block B, B-9000, Ghent, Belgium
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Quantitative aspects of drug permeation across in vitro and in vivo barriers. Eur J Pharm Sci 2015; 87:30-46. [PMID: 26493585 DOI: 10.1016/j.ejps.2015.10.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 10/16/2015] [Accepted: 10/17/2015] [Indexed: 01/09/2023]
Abstract
The kinetics of permeation across epithelial and endothelial cell sheets and across cell membranes is determinant for the pharmacokinetics of a drug. In vitro transport experiments with cultured cells or artificial barriers have tremendously improved the predictability of the in vivo behaviour of tested compounds. This article focuses on the parameters and calculation methods that are used to describe permeation quantitatively, with a focus on in vitro experiments and the prediction of intestinal absorption and blood-brain barrier passage. It shows under which in vitro experimental conditions standard calculations are adequate and under which conditions equations should be adapted to the experimental details. The impact of volume differences between donor and receiver compartments, pH gradients, addition of albumin, accumulation in the barrier and unidirectional transport by an efflux transporter on the results is shown in simulations. The article should make researchers aware of experimental factors that affect the outcome of a permeation experiment and how to account for this during data analysis. Finally, strategies to predict the in vivo behaviour of a compound based on the in vitro data are discussed. The goal of the article is to support researchers in choosing experimental conditions and calculation methods that deliver appropriate and reproducible results in permeation studies in vitro.
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Alf MF, Duarte JMN, Lei H, Krämer SD, Mlynarik V, Schibli R, Gruetter R. MRS glucose mapping and PET joining forces: re-evaluation of the lumped constant in the rat brain under isoflurane anaesthesia. J Neurochem 2014; 129:672-82. [PMID: 24471521 DOI: 10.1111/jnc.12667] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Revised: 01/22/2014] [Accepted: 01/24/2014] [Indexed: 12/17/2022]
Abstract
Although numerous positron emission tomography (PET) studies with (18) F-fluoro-deoxyglucose (FDG) have reported quantitative results on cerebral glucose kinetics and consumption, there is a large variation between the absolute values found in the literature. One of the underlying causes is the inconsistent use of the lumped constants (LCs), the derivation of which is often based on multiple assumptions that render absolute numbers imprecise and errors hard to quantify. We combined a kinetic FDG-PET study with magnetic resonance spectroscopic imaging (MRSI) of glucose dynamics in Sprague-Dawley rats to obtain a more comprehensive view of brain glucose kinetics and determine a reliable value for the LC under isoflurane anaesthesia. Maps of Tmax /CMRglc derived from MRSI data and Tmax determined from PET kinetic modelling allowed to obtain an LC-independent CMRglc . The LC was estimated to range from 0.33 ± 0.07 in retrosplenial cortex to 0.44 ± 0.05 in hippocampus, yielding CMRglc between 62 ± 14 and 54 ± 11 μmol/min/100 g, respectively. These newly determined LCs for four distinct areas in the rat brain under isoflurane anaesthesia provide means of comparing the growing amount of FDG-PET data available from translational studies.
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Affiliation(s)
- Malte F Alf
- Laboratory of Functional and Metabolic Imaging, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland; Center for Radiopharmaceutical Sciences of ETH Zurich, Zurich, Switzerland
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