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Lu J, Mei Q, Hou X, Manaenko A, Zhou L, Liebeskind DS, Zhang JH, Li Y, Hu Q. Imaging Acute Stroke: From One-Size-Fit-All to Biomarkers. Front Neurol 2021; 12:697779. [PMID: 34630278 PMCID: PMC8497192 DOI: 10.3389/fneur.2021.697779] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 06/30/2021] [Indexed: 12/27/2022] Open
Abstract
In acute stroke management, time window has been rigidly used as a guide for decades and the reperfusion treatment is only available in the first few limited hours. Recently, imaging-based selection of patients has successfully expanded the treatment window out to 16 and even 24 h in the DEFUSE 3 and DAWN trials, respectively. Recent guidelines recommend the use of imaging techniques to guide therapeutic decision-making and expanded eligibility in acute ischemic stroke. A tissue window is proposed to replace the time window and serve as the surrogate marker for potentially salvageable tissue. This article reviews the evolution of time window, addresses the advantage of a tissue window in precision medicine for ischemic stroke, and discusses both the established and emerging techniques of neuroimaging and their roles in defining a tissue window. We also emphasize the metabolic imaging and molecular imaging of brain pathophysiology, and highlight its potential in patient selection and treatment response prediction in ischemic stroke.
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Affiliation(s)
- Jianfei Lu
- Central Laboratory, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Qiyong Mei
- Department of Neurosurgery, Changzheng Hospital, Navy Medical University, Shanghai, China
| | - Xianhua Hou
- Department of Neurology, Southwest Hospital, Army Medical University, Chongqing, China
| | - Anatol Manaenko
- National Health Commission Key Laboratory of Diagnosis and Treatment on Brain Functional Diseases, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Lili Zhou
- Department of Neurology, Chinese People's Liberation Army General Hospital, Beijing, China
| | - David S Liebeskind
- Neurovascular Imaging Research Core and University of California Los Angeles Stroke Center, University of California, Los Angeles, Los Angeles, CA, United States
| | - John H Zhang
- Department of Anesthesiology, Loma Linda University School of Medicine, Loma Linda, CA, United States
| | - Yao Li
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Qin Hu
- Central Laboratory, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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Harutyunyan G, Harutyunyan G, Mkhoyan G. New Viewpoint in Exaggerated Increase of PtiO 2 With Normobaric Hyperoxygenation and Reasons to Limit Oxygen Use in Neurotrauma Patients. Front Med (Lausanne) 2018; 5:119. [PMID: 29872657 PMCID: PMC5972302 DOI: 10.3389/fmed.2018.00119] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Accepted: 04/10/2018] [Indexed: 01/06/2023] Open
Affiliation(s)
| | | | - Gagik Mkhoyan
- Anesthesiology and Intensive Care, Erebouni Medical Center, Yerevan, Armenia
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Deuchar GA, Brennan D, Holmes WM, Shaw M, Macrae IM, Santosh C. Perfluorocarbon Enhanced Glasgow Oxygen Level Dependent (GOLD) Magnetic Resonance Metabolic Imaging Identifies the Penumbra Following Acute Ischemic Stroke. Am J Cancer Res 2018; 8:1706-1722. [PMID: 29556351 PMCID: PMC5858177 DOI: 10.7150/thno.21685] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 12/16/2017] [Indexed: 01/27/2023] Open
Abstract
The ability to identify metabolically active and potentially salvageable ischaemic penumbra is crucial for improving treatment decisions in acute stroke patients. Our solution involves two complementary novel MRI techniques (Glasgow Oxygen Level Dependant (GOLD) Metabolic Imaging), which when combined with a perfluorocarbon (PFC) based oxygen carrier and hyperoxia can identify penumbra due to dynamic changes related to continued metabolism within this tissue compartment. Our aims were (i) to investigate whether PFC offers similar enhancement of the second technique (Lactate Change) as previously demonstrated for the T2*OC technique (ii) to demonstrate both GOLD metabolic imaging techniques working concurrently to identify penumbra, following administration of Oxycyte® (O-PFC) with hyperoxia. Methods: An established rat stroke model was utilised. Part-1: Following either saline or PFC, magnetic resonance spectroscopy was applied to investigate the effect of hyperoxia on lactate change in presumed penumbra. Part-2; rats received O-PFC prior to T2*OC (technique 1) and MR spectroscopic imaging, which was used to identify regions of tissue lactate change (technique 2) in response to hyperoxia. In order to validate the techniques, imaging was followed by [14C]2-deoxyglucose autoradiography to correlate tissue metabolic status to areas identified as penumbra. Results: Part-1: PFC+hyperoxia resulted in an enhanced reduction of lactate in the penumbra when compared to saline+hyperoxia. Part-2: Regions of brain tissue identified as potential penumbra by both GOLD metabolic imaging techniques utilising O-PFC, demonstrated maintained glucose metabolism as compared to adjacent core tissue. Conclusion: For the first time in vivo, enhancement of both GOLD metabolic imaging techniques has been demonstrated following intravenous O-PFC+hyperoxia to identify ischaemic penumbra. We have also presented preliminary evidence of the potential therapeutic benefit offered by O-PFC. These unique theranostic applications would enable treatment based on metabolic status of the brain tissue, independent of time from stroke onset, leading to increased uptake and safer use of currently available treatment options.
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Dani KA, Moreton FC, Santosh C, Lopez R, Brennan D, Schwarzbauer C, Goutcher C, O'Hare K, Macrae IM, Muir KW. Oxygen challenge magnetic resonance imaging in healthy human volunteers. J Cereb Blood Flow Metab 2017; 37:366-376. [PMID: 26787107 PMCID: PMC5363753 DOI: 10.1177/0271678x15627827] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Revised: 11/12/2015] [Accepted: 11/16/2015] [Indexed: 11/15/2022]
Abstract
Oxygen challenge imaging involves transient hyperoxia applied during deoxyhaemoglobin sensitive (T2*-weighted) magnetic resonance imaging and has the potential to detect changes in brain oxygen extraction. In order to develop optimal practical protocols for oxygen challenge imaging, we investigated the influence of oxygen concentration, cerebral blood flow change, pattern of oxygen administration and field strength on T2*-weighted signal. Eight healthy volunteers underwent multi-parametric magnetic resonance imaging including oxygen challenge imaging and arterial spin labelling using two oxygen concentrations (target FiO2 of 100 and 60%) administered consecutively (two-stage challenge) at both 1.5T and 3T. There was a greater signal increase in grey matter compared to white matter during oxygen challenge (p < 0.002 at 3T, P < 0.0001 at 1.5T) and at FiO2 = 100% compared to FiO2 = 60% in grey matter at both field strengths (p < 0.02) and in white matter at 3T only (p = 0.0314). Differences in the magnitude of signal change between 1.5T and 3T did not reach statistical significance. Reduction of T2*-weighted signal to below baseline, after hyperoxia withdrawal, confounded interpretation of two-stage oxygen challenge imaging. Reductions in cerebral blood flow did not obscure the T2*-weighted signal increases. In conclusion, the optimal protocol for further study should utilise target FiO2 = 100% during a single oxygen challenge. Imaging at both 1.5T and 3T is clinically feasible.
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Affiliation(s)
- Krishna A Dani
- Institute of Neuroscience and Psychology, College of Medical Veterinary and Life Sciences, University of Glasgow, Queen Elizabeth University Hospital Glasgow, Glasgow
| | - Fiona C Moreton
- Institute of Neuroscience and Psychology, College of Medical Veterinary and Life Sciences, University of Glasgow, Queen Elizabeth University Hospital Glasgow, Glasgow
| | - Celestine Santosh
- Department of Neuroradiology, Institute of Neurological Sciences, Queen Elizabeth University Hospital Glasgow, Glasgow
| | - Rosario Lopez
- Department of Clinical Physics, Institute of Neurological Sciences, Queen Elizabeth University Hospital Glasgow, Glasgow
| | - David Brennan
- Department of Clinical Physics, Institute of Neurological Sciences, Queen Elizabeth University Hospital Glasgow, Glasgow
| | - Christian Schwarzbauer
- University of Applied Sciences Munich, School of Applied Sciences and Mechatronics, München
| | - Colin Goutcher
- Department of Anaesthetics, Institute of Neurological Sciences, Queen Elizabeth University Hospital Glasgow, Glasgow
| | - Kevin O'Hare
- Department of Anaesthetics, Institute of Neurological Sciences, Queen Elizabeth University Hospital Glasgow, Glasgow
| | - I Mhairi Macrae
- Institute of Neuroscience and Psychology, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow
| | - Keith W Muir
- Institute of Neuroscience and Psychology, College of Medical Veterinary and Life Sciences, University of Glasgow, Queen Elizabeth University Hospital Glasgow, Glasgow
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5
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Cardenas DP, Muir ER, Duong TQ. MRI of cerebral blood flow under hyperbaric conditions in rats. NMR IN BIOMEDICINE 2016; 29:961-968. [PMID: 27192391 PMCID: PMC4998963 DOI: 10.1002/nbm.3555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Revised: 03/03/2016] [Accepted: 04/11/2016] [Indexed: 06/05/2023]
Abstract
Hyperbaric oxygen (HBO) therapy has a number of clinical applications. However, the effects of acute HBO on basal cerebral blood flow (CBF) and neurovascular coupling are not well understood. This study explored the use of arterial spin labeling MRI to evaluate changes in baseline and forepaw stimulus-evoked CBF responses in rats (n = 8) during normobaric air (NB), normobaric oxygen (NBO) (100% O2 ), 3 atm absolute (ATA) hyperbaric air (HB) and 3 ATA HBO conditions. T1 was also measured, and the effects of changes in T1 caused by increasing oxygen on the CBF calculation were investigated. The major findings were as follows: (i) increased inhaled oxygen concentrations led to a reduced respiration rate; (ii) increased dissolved paramagnetic oxygen had significant effects on blood and tissue T1 , which affected the CBF calculation using the arterial spin labeling method; (iii) the differences in blood T1 had a larger effect than the differences in tissue T1 on CBF calculation; (iv) if oxygen-induced changes in blood and tissue T1 were not taken into account, CBF was underestimated by 33% at 3 ATA HBO, 10% at NBO and <5% at HB; (v) with correction, CBF values under HBO, HB and NBO were similar (p > 0.05) and all were higher than CBF under NB by ~40% (p < 0.05), indicating that hypercapnia from the reduced respiration rate masks oxygen-induced vasoconstriction, although blood gas was not measured; and (vi) substantial stimulus-evoked CBF increases were detected under HBO, similar to NB, supporting the notion that activation-induced CBF regulation in the brain does not operate through an oxygen-sensing mechanism. CBF MRI provides valuable insights into the effects of oxygen on basal CBF and neurovascular coupling under hyperbaric conditions. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Damon P. Cardenas
- Research Imaging Institute, University of Texas Health Science Center, San Antonio, TX, USA
- Graduate School of Biomedical Science, University of Texas at San Antonio, San Antonio, TX, USA
| | - Eric R. Muir
- Research Imaging Institute, University of Texas Health Science Center, San Antonio, TX, USA
- Department of Ophthalmology, University of Texas Health Science Center, San Antonio, TX, USA
| | - Timothy Q. Duong
- Research Imaging Institute, University of Texas Health Science Center, San Antonio, TX, USA
- Department of Ophthalmology, University of Texas Health Science Center, San Antonio, TX, USA
- South Texas Veterans Health Care System, Department of Veterans Affairs, San Antonio, TX, USA
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6
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Muir ER, Cardenas DP, Duong TQ. MRI of brain tissue oxygen tension under hyperbaric conditions. Neuroimage 2016; 133:498-503. [PMID: 27033683 DOI: 10.1016/j.neuroimage.2016.03.040] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 03/14/2016] [Accepted: 03/17/2016] [Indexed: 11/19/2022] Open
Abstract
The brain depends on a continuous supply of oxygen to maintain its structural and functional integrity. This study measured T1 from MRI under normobaric air, normobaric oxygen, hyperbaric air, and hyperbaric oxygen (HBO) conditions as a marker of tissue pO2 since dissolved molecular oxygen acts as an endogenous contrast agent. Brain tissue T1 decreased corresponding to increased pO2 with increasing inhaled oxygen concentrations, and tissue oxygenation was estimated from the T1 changes between different inhaled oxygen levels. Tissue pO2 difference maps between different oxygen conditions showed heterogeneous pO2 changes in the brain. MRI-derived tissue pO2 was markedly lower than the arterial pO2 but was slightly higher than venous pO2. Additionally, for comparison with published extracellular tissue pO2 data obtained using oxygen electrodes and other invasive techniques, a model was used to estimate extracellular and intracellular pO2 from the MRI-derived mean tissue pO2. This required multiple assumptions, and so the effects of the assumptions and parameters used in modeling brain pO2 were evaluated. MRI-derived pO2 values were strongly dependent on assumptions about the extra- and intracellular compartments but were relatively less sensitive to variations in the relaxivity constant of oxygen and contribution from oxygen in the cerebral blood compartment. This approach may prove useful in evaluating tissue oxygenation in disease states such as stroke.
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Affiliation(s)
- Eric R Muir
- Research Imaging Institute, University of Texas Health Science Center, San Antonio, TX, United States; Department of Ophthalmology, University of Texas Health Science Center, San Antonio, TX, United States.
| | - Damon P Cardenas
- Research Imaging Institute, University of Texas Health Science Center, San Antonio, TX, United States; Graduate School of Biomedical Science, University of Texas at San Antonio, San Antonio, TX, United States
| | - Timothy Q Duong
- Research Imaging Institute, University of Texas Health Science Center, San Antonio, TX, United States; Department of Ophthalmology, University of Texas Health Science Center, San Antonio, TX, United States; South Texas Veterans Health Care System, Department of Veterans Affairs, San Antonio, TX, United States.
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7
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Sun Y, Shen Q, Watts LT, Muir ER, Huang S, Yang GY, Suarez JI, Duong TQ. Multimodal MRI characterization of experimental subarachnoid hemorrhage. Neuroscience 2016; 316:53-62. [PMID: 26708744 PMCID: PMC4724533 DOI: 10.1016/j.neuroscience.2015.12.027] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2015] [Revised: 12/10/2015] [Accepted: 12/14/2015] [Indexed: 01/01/2023]
Abstract
Subarachnoid hemorrhage (SAH) is associated with significant morbidity and mortality. We implemented an in-scanner rat model of mild SAH in which blood or vehicle was injected into the cistern magna, and applied multimodal MRI to study the brain prior to, immediately after (5min to 4h), and upto 7days after SAH. Vehicle injection did not change arterial lumen diameter, apparent diffusion coefficient (ADC), T2, venous signal, vascular reactivity to hypercapnia, or foot-fault scores, but mildly reduce cerebral blood flow (CBF) up to 4h, and open-field activity up to 7days post injection. By contrast, blood injection caused: (i) vasospasm 30min after SAH but not thereafter, (ii) venous abnormalities at 3h and 2days, delayed relative to vasospasm, (iii) reduced basal CBF and to hypercapnia 1-4h but not thereafter, (iv) reduced ADC immediately after SAH but no ADC and T2 changes on days 2 and 7, and (v) reduced open-field activities in both SAH and vehicle animals, but no significant differences in open-field activities and foot-fault tests between groups. Mild SAH exhibited transient and mild hemodynamic disturbances and diffusion changes, but did not show apparent ischemic brain injury nor functional deficits.
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Affiliation(s)
- Y Sun
- Department of Neurosurgery, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China; Department of Stereotactic and Functional Neurosurgery, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China; Research Imaging Institute, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Q Shen
- Research Imaging Institute, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - L T Watts
- Research Imaging Institute, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA; Department of Cellular and Structural Biology, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA; Department of Neurology, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - E R Muir
- Research Imaging Institute, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - S Huang
- Research Imaging Institute, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - G-Y Yang
- Department of Neurosurgery, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China; Department of Stereotactic and Functional Neurosurgery, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China; Neuroscience and Neuroengineering Research Center, Med-X Research Institute, Shanghai Jiao Tong University, Shanghai 200030, China
| | - J I Suarez
- Division of Vascular Neurology and Neurocritical Care, Department of Neurology, Baylor College of Medicine, Baylor St Luke's Medical Center, Houston, TX 77027, USA
| | - T Q Duong
- Research Imaging Institute, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA.
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8
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Shen Q, Huang S, Duong TQ. T2*-weighted fMRI time-to-peak of oxygen challenge in ischemic stroke. J Cereb Blood Flow Metab 2016; 36:283-91. [PMID: 26661164 PMCID: PMC4759668 DOI: 10.1177/0271678x15606461] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Accepted: 07/11/2015] [Indexed: 11/16/2022]
Abstract
T2 (*)-weighted MRI of transient oxygen challenge (OC) showed exaggerated OC percent changes in the ischemic tissue at risk compared to normal tissue. One ambiguity is that regions with high vascular density also showed exaggerated OC percent changes. This study explored time-to-peak (TTP) of the OC percent changes to improve the utility of T2 (*)-weighted OC MRI. Experiments were performed longitudinally at 30 min, 150 min and 24 h after transient (60-min) stroke in rats. Ischemic core, normal, and mismatch tissue were classified pixel-by-pixel based on apparent diffusion coefficient and cerebral blood flow. Major findings were: (i) Delayed OC TTP was localized to and corresponded well with the perfusion-diffusion mismatch. (ii) By contrast, the exaggerated OC percent changes were less localized, with changes not only in the at-risk tissue but also in some areas of the contralesional hemisphere with venous vessel origins. (iii) The OC time-course of the mismatch tissue was biphasic, with a faster initial increase followed by a slower increase. (iv) At-risk tissue with delayed TTP and exaggerated OC was normal after reperfusion and the at-risk tissue was mostly (83 ± 18%) rescued by reperfusion as indicated by normal 24-h T2. OC TTP offers unique information toward better characterization of at-risk tissue in ischemic stroke.
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Affiliation(s)
- Qiang Shen
- Research Imaging Institute, University of Texas Health Science Center, San Antonio, TX, USA Department of Ophthalmology, University of Texas Health Science Center, San Antonio, TX, USA Department of Radiology, University of Texas Health Science Center, San Antonio, TX, USA
| | - Shiliang Huang
- Research Imaging Institute, University of Texas Health Science Center, San Antonio, TX, USA
| | - Timothy Q Duong
- Research Imaging Institute, University of Texas Health Science Center, San Antonio, TX, USA Department of Ophthalmology, University of Texas Health Science Center, San Antonio, TX, USA Department of Radiology, University of Texas Health Science Center, San Antonio, TX, USA South Texas Veterans Health Care System, Department of Veterans Affairs, San Antonio, TX, USA
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9
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Jiang Z, Watts LT, Huang S, Shen Q, Rodriguez P, Chen C, Zhou C, Duong TQ. The Effects of Methylene Blue on Autophagy and Apoptosis in MRI-Defined Normal Tissue, Ischemic Penumbra and Ischemic Core. PLoS One 2015; 10:e0131929. [PMID: 26121129 PMCID: PMC4488003 DOI: 10.1371/journal.pone.0131929] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Accepted: 06/09/2015] [Indexed: 12/11/2022] Open
Abstract
Methylene blue (MB) USP, which has energy-enhancing and antioxidant properties, is currently used to treat methemoglobinemia and cyanide poisoning in humans. We recently showed that MB administration reduces infarct volume and behavioral deficits in rat models of ischemic stroke and traumatic brain injury. This study reports the underlying molecular mechanisms of MB neuroprotection following transient ischemic stroke in rats. Rats were subjected to transient (60-mins) ischemic stroke. Multimodal MRI during the acute phase and at 24 hrs were used to define three regions of interest (ROIs): i) the perfusion-diffusion mismatch salvaged by reperfusion, ii) the perfusion-diffusion mismatch not salvaged by reperfusion, and iii) the ischemic core. The tissues from these ROIs were extracted for western blot analyses of autophagic and apoptotic markers. The major findings were: 1) MB treatment reduced infarct volume and behavioral deficits, 2) MB improved cerebral blood flow to the perfusion-diffusion mismatch tissue after reperfusion and minimized harmful hyperperfusion 24 hrs after stroke, 3) MB inhibited apoptosis and enhanced autophagy in the perfusion-diffusion mismatch, 4) MB inhibited apoptotic signaling cascades (p53-Bax-Bcl2-Caspase3), and 5) MB enhanced autophagic signaling cascades (p53-AMPK-TSC2-mTOR). MB induced neuroprotection, at least in part, by enhancing autophagy and reducing apoptosis in the perfusion-diffusion mismatch tissue following ischemic stroke.
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Affiliation(s)
- Zhao Jiang
- Department of Anatomy and Embryology, Peking University Health Science Center, Beijing, China
- Research Imaging Institute, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Lora Talley Watts
- Research Imaging Institute, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Shiliang Huang
- Research Imaging Institute, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Qiang Shen
- Research Imaging Institute, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Pavel Rodriguez
- Research Imaging Institute, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Chunhua Chen
- Department of Anatomy and Embryology, Peking University Health Science Center, Beijing, China
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Changman Zhou
- Department of Anatomy and Embryology, Peking University Health Science Center, Beijing, China
| | - Timothy Q. Duong
- Research Imaging Institute, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
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Huang CH, Shih YYI, Siow TY, Hsu YH, Chen CCV, Lin TN, Jaw FS, Chang C. Temporal assessment of vascular reactivity and functionality using MRI during postischemic proangiogenenic vascular remodeling. Magn Reson Imaging 2015; 33:903-10. [PMID: 25944092 DOI: 10.1016/j.mri.2015.04.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Revised: 03/13/2015] [Accepted: 04/26/2015] [Indexed: 11/18/2022]
Abstract
Postischemic angiogenesis is an important recovery mechanism. Both arteries and veins are upregulated during angiogenesis, but eventually there are more angiogenic veins than arteries in terms of number and length. It is critical to understand how the veins are modulated after ischemia and then transitioned into angiogenic vessels during the proangiogenic stage to finally serve as a restorative strength to the injured area. Using a rat model of transient focal cerebral ischemia, the hypercapnic blood oxygen level-dependent (BOLD) response was used to evaluate vascular reactivity, while the hyperoxic BOLD and tissue oxygen level-dependent (TOLD) responses were used to evaluate the vascular functionality at 1, 3, and 7days after ischemia. Vessel-like venous signals appeared on R2* maps on days 3 and 7, but not on day 1. The large hypercapnic BOLD responses on days 3 and 7 indicated that these areas have high vascular reactivity. The temporal correlation between vascular reactivity and the immunoreactivity to desmin and VEGF further indicates that the integrity of vascular reactivity is associated with the pericyte coverage as regulated by the VEGF level. Vascular functionality remained low on days 1, 3, and 7, as reflected by the small hyperoxic BOLD and large hyperoxic TOLD responses, indicating the low oxygen consumption of the ischemic tissues. These functional changes in proangiogenic veins may be critical for angiogenesis.
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Affiliation(s)
- Chien-Hsiang Huang
- Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan; Institute of Biomedical Sciences, Academic Sinica, Taipei, Taiwan
| | - Yen-Yu Ian Shih
- Experimental Neuroimaging Laboratory, Department of Neurology and Biomedical Research Imaging Center, University of North Carolina, Chapel Hill, NC, USA
| | - Tiing-Yee Siow
- Department of Medical Imaging and Intervention, Chang-Gung Memorial Hospital, Chang-Gung University College of Medicine, Taoyuan, Taiwan
| | - Yi-Hua Hsu
- Institute of Biomedical Sciences, Academic Sinica, Taipei, Taiwan
| | - Chiao-Chi V Chen
- Institute of Biomedical Sciences, Academic Sinica, Taipei, Taiwan
| | - Teng-Nan Lin
- Institute of Biomedical Sciences, Academic Sinica, Taipei, Taiwan
| | - Fu-Shan Jaw
- Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan.
| | - Chen Chang
- Institute of Biomedical Sciences, Academic Sinica, Taipei, Taiwan.
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11
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Dani KA, Warach S. Metabolic imaging of ischemic stroke: the present and future. AJNR Am J Neuroradiol 2014; 35:S37-43. [PMID: 24722308 DOI: 10.3174/ajnr.a3789] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Measures of cerebral metabolism may be useful in the selection of patients for reperfusion therapies and as end points in clinical trials. However, there are currently no clinically routine techniques that provide such data directly. We review how imaging modalities in current clinical use may provide surrogate markers of metabolic activity. Promising techniques for metabolic imaging that are currently in the pipeline are reviewed.
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Affiliation(s)
- K A Dani
- From the Institute of Neurosciences and Psychology (K.A.D.), University of Glasgow, Institute of Neurological Sciences, Glasgow, United Kingdom
| | - S Warach
- Department of Neurology and Neurotherapeutics (S.W.), UT Southwestern, Dallas, Texas.
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12
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Abstract
The ability to image the ischemic penumbra during hyper-acute stroke promises to identify patients who may benefit from treatment intervention beyond population-defined therapeutic time windows. MR blood oxygenation level dependent (BOLD) contrast imaging has been explored in ischemic stroke. This review provides an overview of several BOLD-based methods, including susceptibility weighted imaging (SWI), R2, R2*, R2', R2* under oxygen challenge, MR_OEF and MROMI approaches to assess cerebral oxygen metabolism in ischemic stroke. We will review the underlying pathophysiological basis of the imaging approaches, followed by a brief introduction of BOLD contrast. Finally, we will discuss the applications of the BOLD approaches in patients with ischemic stroke. BOLD-based methods hold promise for imaging tissue oxygenation during acute ischemia. Further technical refinement and validation studies in stroke patients against positron emission tomography (PET) measurements are needed.
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13
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Shen Q, Du F, Huang S, Duong TQ. Effects of cerebral ischemic and reperfusion on T2*-weighted MRI responses to brief oxygen challenge. J Cereb Blood Flow Metab 2014; 34:169-75. [PMID: 24129750 PMCID: PMC3887355 DOI: 10.1038/jcbfm.2013.179] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Revised: 08/19/2013] [Accepted: 09/19/2013] [Indexed: 11/09/2022]
Abstract
This study characterized the effects of cerebral ischemia and reperfusion on T2*-weighted magnetic resonance image (MRI) responses to brief oxygen challenge (OC) in transient (60 minutes) cerebral ischemia in rats. During occlusion, the ischemic core tissue showed no significant OC response, whereas the perfusion-diffusion mismatch tissue showed markedly higher percent changes relative to normal tissue. After reperfusion, much of the pixels with initial exaggerated OC responses showed normal OC responses, and the majority of these tissues were salvaged as defined by endpoint T2 MRI. The initial core pixels showed exaggerated OC responses after reperfusion, but the majority of the core pixels eventually became infarct, suggesting exaggerated OC responses do not necessarily reflect salvageable tissue. Twenty-four hours after stroke, basal T1 increased in the ischemic core. Oxygen challenge decreased T1 significantly in the core, indicative of the substantial increases in dissolved oxygen in the core as the result of hyperperfusion. We concluded that exaggerated T2*-weighted MRI responses to OC offer useful insight in ischemic tissue fates. However, exaggerated OC pixels are not all salvageable, and they exhibited complex dynamics depending on reperfusion status, hyperperfusion, and edema effects.
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Affiliation(s)
- Qiang Shen
- 1] Department of Research Imaging Institute, San Antonio, Texas, USA [2] Department of Ophthalmology, San Antonio, Texas, USA [3] Department of Radiology, University of Texas Health Science Center, San Antonio, Texas, USA
| | - Fang Du
- Department of Research Imaging Institute, San Antonio, Texas, USA
| | - Shiliang Huang
- Department of Research Imaging Institute, San Antonio, Texas, USA
| | - Timothy Q Duong
- 1] Department of Research Imaging Institute, San Antonio, Texas, USA [2] Department of Ophthalmology, San Antonio, Texas, USA [3] Department of Radiology, University of Texas Health Science Center, San Antonio, Texas, USA [4] South Texas Veterans Health Care System, Department of Veterans Affairs, San Antonio, Texas, USA
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14
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Muir ER, Watts LT, Tiwari YV, Bresnen A, Shen Q, Duong TQ. Quantitative cerebral blood flow measurements using MRI. Methods Mol Biol 2014; 1135:205-11. [PMID: 24510866 DOI: 10.1007/978-1-4939-0320-7_17] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Magnetic resonance imaging can be utilized as a quantitative and noninvasive method to image cerebral blood flow. The two most common techniques used to detect cerebral blood flow are dynamic susceptibility contrast (DSC) perfusion MRI and arterial spin labeling perfusion MRI. Herein we describe the use of these two techniques to measure cerebral blood flow in rodents, including methods, analysis, and important considerations when utilizing these techniques.
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Affiliation(s)
- Eric R Muir
- Department of Ophthalmology, Research Imaging Institute, University of Texas Health Science Center, San Antonio, TX, USA
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15
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Muir ER, Cardenas D, Huang S, Roby J, Li G, Duong TQ. MRI under hyperbaric air and oxygen: effects on local magnetic field and relaxation times. Magn Reson Med 2013; 72:1176-81. [PMID: 24243603 DOI: 10.1002/mrm.25027] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Revised: 09/30/2013] [Accepted: 10/11/2013] [Indexed: 11/11/2022]
Abstract
PURPOSE Hyperbaric oxygen therapy has shown efficacies in the treatment of a number of diseases. The goal of this study was to develop a rodent hyperbaric chamber for MRI studies and to investigate the effects of hyperbaric air and hyperbaric oxygen on local magnetic field (B0 ) and MRI relaxation parameters in the rat brain. METHODS A hyperbaric chamber, constructed to fit inside an animal MRI scanner, was pressurized with air to four atmospheres, while oxygen was delivered locally via nose cone. B0 , T2 , T2 *, and T1 maps in the rat brain were evaluated under normobaric air, hyperbaric air, and hyperbaric oxygen at 7T. RESULTS Under hyperbaric oxygen, images exhibited artifacts and temporal instability, attributable to fluctuating oxygen concentration from air and oxygen mixing near the imaging region. Physically shielding the imaging region from fluctuating oxygen concentration resolved the problems. With increasing oxygen at hyperbaric pressure, B0 was shifted downfield with increased inhomogeneity near the ear canals and nose. Brain T2 and T2 * were lengthened, and T1 was shortened. CONCLUSION This study establishes the means to perform MRI on rodents under hyperbaric conditions. Hyperbaric air and hyperbaric oxygen have significant effects on B0 and tissue relaxation parameters compared with normobaric air.
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Affiliation(s)
- Eric R Muir
- Department of Ophthalmology, University of Texas Health Science Center, San Antonio, Texas, USA; Research Imaging Institute, University of Texas Health Science Center, San Antonio, Texas, USA
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16
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Deuchar GA, Brennan D, Griffiths H, Macrae I M, Santosh C. Perfluorocarbons enhance a T2*-based MRI technique for identifying the penumbra in a rat model of acute ischemic stroke. J Cereb Blood Flow Metab 2013; 33:1422-8. [PMID: 23801243 PMCID: PMC3764387 DOI: 10.1038/jcbfm.2013.86] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Revised: 04/22/2013] [Accepted: 05/01/2013] [Indexed: 02/05/2023]
Abstract
Accurate imaging of ischemic penumbra is crucial for improving the management of acute stroke patients. T2* magnetic resonance imaging (MRI) combined with a T2*oxygen challenge (T2*OC) is being developed to detect penumbra based on changes in blood deoxyhemoglobin. Using 100% O2, T2*OC-defined penumbra exhibits ongoing glucose metabolism and tissue recovery on reperfusion. However, potential limitations in translating this technique include a sinus artefact in human scans with delivery of 100% OC and relatively small signal changes. Here we investigate whether an oxygen-carrying perfluorocarbon (PFC) emulsion can enhance the sensitivity of the technique, enabling penumbra detection with lower levels of inspired oxygen. Stroke was induced in male Sprague-Dawley rats (n=17) with ischemic injury and perfusion deficit determined by diffusion and perfusion MRI, respectively. T2* signal change was measured in regions of interest (ROIs) located within ischemic core, T2*OC-defined penumbra and equivalent contralateral areas during 40% O2±prior PFC injection. Region of interest analyses between groups showed that PFC significantly enhanced the T2* response to 40% O2 in T2*-defined penumbra (mean increase of 10.6±2.3% compared to 5.6±1.5% with 40% O2, P<0.001). This enhancement was specific to the penumbra ROI. Perfluorocarbon emulsions therefore enhances the translational potential of the T2*OC technique for identifying penumbra in acute stroke patients.
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Affiliation(s)
- Graeme A Deuchar
- Wellcome Surgical Institute, Glasgow Experimental MRI Centre, Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - David Brennan
- Department of Neuroradiology, Institute of Neurological Sciences, Southern General Hospital, Glasgow, UK
| | - Hugh Griffiths
- Department of Neuroradiology, Institute of Neurological Sciences, Southern General Hospital, Glasgow, UK
| | - I Mhairi Macrae
- Wellcome Surgical Institute, Glasgow Experimental MRI Centre, Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Celestine Santosh
- Department of Neuroradiology, Institute of Neurological Sciences, Southern General Hospital, Glasgow, UK
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17
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Abstract
Stroke is a serious healthcare problem with high mortality and long-term disability. However, to date, our ability to prevent and cure stroke remains limited. One important goal in stroke research is to identify the extent and location of lesion for treatment. In addition, accurately differentiating salvageable tissue from infarct and evaluating therapeutic efficacies are indispensible. These objectives could potentially be met with the assistance of modern neuroimaging techniques. This paper reviews current imaging methods commonly used in ischemic stroke research. These methods include positron emission tomography, computed tomography, T1 MRI, T2 MRI, diffusion and perfusion MRI, diffusion tensor imaging, blood-brain barrier permeability MRI, pH-weighted MRI, and functional MRI.
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Affiliation(s)
- Hsiao-Ying Wey
- University of Texas Health Science Center, San Antonio, Texas, USA
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18
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Stroke neuroprotection: targeting mitochondria. Brain Sci 2013; 3:540-60. [PMID: 24961414 PMCID: PMC4061853 DOI: 10.3390/brainsci3020540] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Revised: 04/08/2013] [Accepted: 04/09/2013] [Indexed: 11/17/2022] Open
Abstract
Stroke is the fourth leading cause of death and the leading cause of long-term disability in the United States. Blood flow deficit results in an expanding infarct core with a time-sensitive peri-infarct penumbra that is considered salvageable and is the primary target for treatment strategies. The only current FDA-approved drug for treating ischemic stroke is recombinant tissue plasminogen activator (rt-PA). However, this treatment is limited to within 4.5 h of stroke onset in a small subset of patients. The goal of this review is to focus on mitochondrial-dependent therapeutic agents that could provide neuroprotection following stroke. Dysfunctional mitochondria are linked to neurodegeneration in many disease processes including stroke. The mechanisms reviewed include: (1) increasing ATP production by purinergic receptor stimulation, (2) decreasing the production of ROS by superoxide dismutase, or (3) increasing antioxidant defenses by methylene blue, and their benefits in providing neuroprotection following a stroke.
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19
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Duong TQ. Magnetic resonance imaging of perfusion-diffusion mismatch in rodent and non-human primate stroke models. Neurol Res 2013; 35:465-9. [PMID: 23594679 DOI: 10.1179/1743132813y.0000000211] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Stroke is a leading cause of death and long-term disability. Non-invasive magnetic resonance imaging (MRI) has been widely used for the early detection of ischemic stroke and the longitudinal monitoring of novel treatment strategies. Recent advances in MRI techniques have enabled improved sensitivity and specificity to detecting ischemic brain injury and monitoring functional recovery. This review describes recent progresses in the development and application of multimodal MRI and image analysis techniques to study experimental stroke in rats and non-human primates.
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Affiliation(s)
- Timothy Q Duong
- South Texas Veterans Health Care System, Department of Veterans Affairs, San Antonio, TX, USA.
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20
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Jensen-Kondering U, Baron JC. Oxygen imaging by MRI: can blood oxygen level-dependent imaging depict the ischemic penumbra? Stroke 2012; 43:2264-9. [PMID: 22588263 DOI: 10.1161/strokeaha.111.632455] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Ulf Jensen-Kondering
- Stroke Research Group, University of Cambridge, Department of Clinical Neurosciences, Addenbrooke's Hospital, Cambridge, UK
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21
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Duong TQ. Multimodal MRI of experimental stroke. Transl Stroke Res 2011; 3:8-15. [PMID: 24323751 DOI: 10.1007/s12975-011-0140-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2011] [Revised: 12/01/2011] [Accepted: 12/05/2011] [Indexed: 10/14/2022]
Abstract
Stroke is the fourth leading cause of death and the leading cause of long-term disability in USA. Brain imaging data from experimental stroke models and stroke patients have shown that there is often a gradual progression of potentially reversible ischemic injury toward infarction. Reestablishing tissue perfusion and/or treating with neuroprotective drugs in a timely fashion are expected to salvage some ischemic tissues. Diffusion-weighted imaging based on magnetic resonance imaging (MRI) in which contrast is based on water motion can detect ischemic injury within minutes after onsets, whereas computed tomography and other imaging modalities fail to detect stroke injury for at least a few hours. Along with quantitative perfusion imaging, the perfusion-diffusion mismatch which approximates the ischemic penumbra could be imaged noninvasively. This review describes recent progresses in the development and application of multimodal MRI and image analysis techniques to study ischemic tissue at risk in experimental stroke in rats.
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Affiliation(s)
- Timothy Q Duong
- Research Imaging Institute, Departments of Ophthalmology, Radiology and Physiology, University of Texas Health Science Center, 8403 Floyd Curl Dr, San Antonio, TX, 78229, USA,
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22
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Obenaus A, Ashwal S. Neuroimaging of stroke and ischemia in animal models. Transl Stroke Res 2011; 3:4-7. [PMID: 24323750 DOI: 10.1007/s12975-011-0139-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2011] [Accepted: 11/30/2011] [Indexed: 12/12/2022]
Abstract
Magnetic resonance imaging (MRI) has dramatically changed our ability to diagnose and treat stroke as well as follow its evolution and response to treatment. Early stroke and ischemia can be visualized using diffusion-weighted imaging that utilizes water diffusion within tissues as a reporter for evolving neuropathology that reflects cytotoxic edema, particularly during the first several days after injury. T2-weighted imaging is used for evaluation of vasogenic edema but also is a reliable indicator of the volume and regional distribution of injured tissues. Perfusion-weighted imaging can be used to assess vascular function and also to evaluate potential tissues that might be rescued using therapeutic interventions (core vs. penumbra). Other imaging modalities such as magnetic resonance spectroscopy, diffusion tensor imaging, and susceptibility-weighted imaging are also being used to assist in rapid diagnosis of injured tissues following stroke. While visual analysis of MR data can provide some information about the evolution of injury, quantitative analyses allow definitive and objective evaluations of the injury and could be used to assess novel therapeutic strategies. We review here the basic uses of neuroimaging, focusing on MR approaches to assess stroke and ischemic injury in animal models.
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Affiliation(s)
- Andre Obenaus
- Non-Invasive Imaging Laboratory, Department of Radiation Medicine, Loma Linda University, 11175 Campus St, CSPA1010, Loma Linda, CA, 92324, USA,
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