1
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Wang X, Zhang H, Wang Q, Li G, Shen H, Xiao Y, Xu L, Long Y, Chen C, Huang Z, Zhang Y. Effect of intravenous thrombolysis on core growth rate in patients with acute cerebral infarction. Front Neurol 2023; 14:1096605. [PMID: 36908588 PMCID: PMC9996056 DOI: 10.3389/fneur.2023.1096605] [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: 11/12/2022] [Accepted: 01/30/2023] [Indexed: 02/25/2023] Open
Abstract
Objective This study aimed to investigate the effects of recombinant tissue plasminogen activator intravenous thrombolysis (IVT) on the core growth rate of acute ischemic stroke. Methods Stroke patients with large vessel occlusion and non-recanalization from IVT treatment were retrospectively included in this study and divided into two groups: IVT and non-IVT. The core growth rate was estimated by the acute core volume on perfusion CT divided by the last known well time from stroke to CT perfusion. The primary endpoint was the core growth rate, the tissue outcome was 24 h-ASPECTS, and the clinical outcome was a 3-month modified Rankin score. Results A total of 94 patients were included with 53 in the IVT group and 41 in the non-IVT group. There was no significant difference in age, gender, hypertension, diabetes, atrial fibrillation, acute NIHSS, and last known well time from stroke to CT perfusion acquisition between the two groups. The core growth rate in the IVT group was lower than that in the non-IVT group, which was statistically significant after multivariate adjustment (coefficient: -5.20, 95% CI= [-9.85, -0.56], p = 0.028). There was a significant interaction between the IVT and the collateral index in predicting the core growth rate. The analysis was then stratified according to the collateral index, and the results suggested that IVT reduced the core growth rate more significantly after the worsening of collateral circulation (coefficient: 15.38, 95% CI= [-26.25, -4.40], p = 0.007). The 3-month modified Rankin score and 24 h-ASPECTS were not statistically significant between the two groups. Conclusion Intravenous thrombolysis reduces the core growth rate in patients with AIS, especially those with poor collateral status.
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Affiliation(s)
- Xueqi Wang
- Shanghai East Hospital, Tongji University, Shanghai, China
| | - Hao Zhang
- Shanghai East Hospital, Tongji University, Shanghai, China
| | - Qi Wang
- Shanghai East Hospital, Tongji University, Shanghai, China
| | - Gang Li
- Shanghai East Hospital, Tongji University, Shanghai, China
| | - Hao Shen
- Shanghai East Hospital, Tongji University, Shanghai, China
| | - Yaping Xiao
- Shanghai East Hospital, Tongji University, Shanghai, China
| | - Luran Xu
- Shanghai East Hospital, Tongji University, Shanghai, China
| | - Yuming Long
- Shanghai East Hospital, Tongji University, Shanghai, China
| | - Chen Chen
- Shanghai East Hospital, Tongji University, Shanghai, China
| | - Zhengyu Huang
- Shanghai East Hospital, Tongji University, Shanghai, China
| | - Yue Zhang
- Shanghai East Hospital, Tongji University, Shanghai, China
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2
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Paydarfar DA, Paydarfar D, Mucha PJ, Chang J. Optimizing Emergency Stroke Transport Strategies Using Physiological Models. Stroke 2021; 52:4010-4020. [PMID: 34407639 PMCID: PMC8607917 DOI: 10.1161/strokeaha.120.031633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Supplemental Digital Content is available in the text. The criteria for choosing between drip and ship and mothership transport strategies in emergency stroke care is widely debated. Although existing data-driven probability models can inform transport decision-making at an epidemiological level, we propose a novel mathematical, physiologically derived framework that provides insight into how patient characteristics underlying infarct core growth influence these decisions.
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Affiliation(s)
- Daniel A Paydarfar
- Carolina Center for Interdisciplinary Applied Mathematics, Department of Mathematics (D.A.P., P.J.M.), University of North Carolina, Chapel Hill
| | - David Paydarfar
- Departments of Neurology (D.P., J.C.), Dell Medical School, Mulva Clinic for the Neurosciences and Oden Institute for Computational Engineering and Sciences, The University of Texas at Austin
| | - Peter J Mucha
- Carolina Center for Interdisciplinary Applied Mathematics, Department of Mathematics (D.A.P., P.J.M.), University of North Carolina, Chapel Hill
| | - Joshua Chang
- Departments of Neurology (D.P., J.C.), Dell Medical School, Mulva Clinic for the Neurosciences and Oden Institute for Computational Engineering and Sciences, The University of Texas at Austin.,Population Health (J.C.), Dell Medical School, Mulva Clinic for the Neurosciences and Oden Institute for Computational Engineering and Sciences, The University of Texas at Austin
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3
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Little PV, Arnberg F, Jussing E, Lu L, Ingemann Jensen A, Mitsios N, Mulder J, Tran TA, Holmin S. The cellular basis of increased PET hypoxia tracer uptake in focal cerebral ischemia with comparison between [ 18F]FMISO and [ 64Cu]CuATSM. J Cereb Blood Flow Metab 2021; 41:617-629. [PMID: 32423333 PMCID: PMC7922752 DOI: 10.1177/0271678x20923857] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 03/31/2020] [Accepted: 04/12/2020] [Indexed: 11/16/2022]
Abstract
PET hypoxia imaging can assess tissue viability in acute ischemic stroke (AIS). [18F]FMISO is an established tracer but requires substantial accumulation time, limiting its use in hyperacute AIS. [64Cu]CuATSM requires less accumulation time and has shown promise as a hypoxia tracer. We compared these tracers in a M2-occlusion model (M2CAO) with preserved collateral blood flow. Rats underwent M2CAO and [18F]FMISO (n = 12) or [64Cu]CuATSM (n = 6) examinations. [64Cu]CuATSM animals were also examined with MRI. Pimonidazole was used as a surrogate for [18F]FMISO in an immunofluorescence analysis employed to profile levels of hypoxia in neurons (NeuN) and astrocytes (GFAP). There was increased [18F]FMISO uptake in the M2CAO cortex. No increase in [64Cu]CuATSM activity was found. The pimonidazole intensity of neurons and astrocytes was increased in hypoxic regions. The pimonidazole intensity ratio was higher in neurons than in astrocytes. In the majority of animals, immunofluorescence revealed a loss of astrocytes within the core of regions with increased pimonidazole uptake. We conclude that [18F]FMISO is superior to [64Cu]CuATSM in detecting hypoxia in AIS, consistent with an earlier study. [18F]FMISO may provide efficient diagnostic imaging beyond the hyperacute phase. Results do not provide encouragement for the use of [64Cu]CuATSM in experimental AIS.
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Affiliation(s)
- Philip V Little
- The Department of Clinical Neuroscience, Karolinska Institutet,
Stockholm Sweden
- The Department of Neuroradiology, BioClinicum, Karolinska
University Hospital, Stockholm, Sweden
| | - Fabian Arnberg
- The Department of Clinical Neuroscience, Karolinska Institutet,
Stockholm Sweden
- The Department of Neuroradiology, BioClinicum, Karolinska
University Hospital, Stockholm, Sweden
| | - Emma Jussing
- The Department of Clinical Neuroscience, Karolinska Institutet,
Stockholm Sweden
- The Department of Radiopharmacy, Karolinska University Hospital,
Stockholm, Sweden
- The Department of Oncology and Pathology, Karolinska Institutet,
Stockholm Sweden
| | - Li Lu
- The Department of Clinical Neuroscience, Karolinska Institutet,
Stockholm Sweden
- The Department of Radiopharmacy, Karolinska University Hospital,
Stockholm, Sweden
- The Department of Oncology and Pathology, Karolinska Institutet,
Stockholm Sweden
| | | | - Nicholas Mitsios
- The Department of Neuroscience, Karolinska Institutet,
Stockholm, Sweden
| | - Jan Mulder
- The Department of Neuroscience, Karolinska Institutet,
Stockholm, Sweden
| | - Thuy A Tran
- The Department of Clinical Neuroscience, Karolinska Institutet,
Stockholm Sweden
- The Department of Radiopharmacy, Karolinska University Hospital,
Stockholm, Sweden
- The Department of Oncology and Pathology, Karolinska Institutet,
Stockholm Sweden
| | - Staffan Holmin
- The Department of Clinical Neuroscience, Karolinska Institutet,
Stockholm Sweden
- The Department of Neuroradiology, BioClinicum, Karolinska
University Hospital, Stockholm, Sweden
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4
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Gómez-Lado N, López-Arias E, Iglesias-Rey R, Díaz-Platas L, Medín-Aguerre S, Fernández-Ferreiro A, Posado-Fernández A, García-Varela L, Rodríguez-Pérez M, Campos F, Del Pino P, Ruibal Á, Pardo-Montero J, Castillo J, Aguiar P, Sobrino T. [ 18F]-FMISO PET/MRI Imaging Shows Ischemic Tissue around Hematoma in Intracerebral Hemorrhage. Mol Pharm 2020; 17:4667-4675. [PMID: 33186043 DOI: 10.1021/acs.molpharmaceut.0c00932] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Intracerebral hemorrhage (ICH), being the most severe cerebrovascular disease, accounts for 10-15% of all strokes. Hematoma expansion is one of the most important factors associated with poor outcome in intracerebral hemorrhage (ICH). Several studies have suggested that an "ischemic penumbra" might arise when the hematoma has a large expansion, but clinical studies are inconclusive. We performed a preclinical study to demonstrate the presence of hypoxic-ischemic tissue around the hematoma by means of longitudinal [18F]-fluoromisonidazole ([18F]-FMISO) PET/MRI studies over time in an experimental ICH model. Our results showed that all [18F]-FMISO PET/MRI images exhibited hypoxic-ischemic tissue around the hematoma area. A significant increase of [18F]-FMISO uptake was found at 18-24 h post-ICH when the maximum of hematoma volume is achieved and this increase disappeared before 42 h. These results demonstrate the presence of hypoxic tissue around the hematoma and open the possibility of new therapies aimed to reduce ischemic damage associated with ICH.
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Affiliation(s)
- Noemí Gómez-Lado
- Molecular Imaging Research Group, Nuclear Medicine Department, Health Research Institute of Santiago de Compostela (IDIS), Santiago de Compostela 15706, Spain.,Molecular Imaging and Medical Physics Group, Psychiatry, Radiology, Public Health, Nursing and Medicine Department, University of Santiago de Compostela (USC), University Clinical Hospital, Santiago de Compostela 15706, Spain
| | - Esteban López-Arias
- Clinical Neurosciences Research Laboratory, Health Research Institute of Santiago de Compostela (IDIS), Santiago de Compostela 15706, Spain
| | - Ramón Iglesias-Rey
- Clinical Neurosciences Research Laboratory, Health Research Institute of Santiago de Compostela (IDIS), Santiago de Compostela 15706, Spain
| | - Lucía Díaz-Platas
- Galician PET Radiopharmacy Unit, GALARIA, University Clinical Hospital, Santiago de Compostela 15706, Spain
| | - Santiago Medín-Aguerre
- Galician PET Radiopharmacy Unit, GALARIA, University Clinical Hospital, Santiago de Compostela 15706, Spain
| | - Anxo Fernández-Ferreiro
- Pharmacology Group, Pharmacy Department, University Clinical Hospital, University of Santiago de Compostela, Health Research Institute of Santiago de Compostela (IDIS), Santiago de Compostela 15706, Spain
| | - Adrián Posado-Fernández
- Clinical Neurosciences Research Laboratory, Health Research Institute of Santiago de Compostela (IDIS), Santiago de Compostela 15706, Spain
| | - Lara García-Varela
- Molecular Imaging Research Group, Nuclear Medicine Department, Health Research Institute of Santiago de Compostela (IDIS), Santiago de Compostela 15706, Spain
| | - Manuel Rodríguez-Pérez
- Clinical Neurosciences Research Laboratory, Health Research Institute of Santiago de Compostela (IDIS), Santiago de Compostela 15706, Spain
| | - Francisco Campos
- Clinical Neurosciences Research Laboratory, Health Research Institute of Santiago de Compostela (IDIS), Santiago de Compostela 15706, Spain
| | - Pablo Del Pino
- Center for Research in Biological Chemistry and Molecular Materials (CIQUS), Particle Physics Departament, University of Santiago de Compostela, Santiago de Compostela 15706, Spain
| | - Álvaro Ruibal
- Molecular Imaging Research Group, Nuclear Medicine Department, Health Research Institute of Santiago de Compostela (IDIS), Santiago de Compostela 15706, Spain.,Molecular Imaging and Medical Physics Group, Psychiatry, Radiology, Public Health, Nursing and Medicine Department, University of Santiago de Compostela (USC), University Clinical Hospital, Santiago de Compostela 15706, Spain
| | - Juan Pardo-Montero
- Group of Medical Physics and Biomathematics, Health Research Institute of Santiago de Compostela (IDIS), Santiago de Compostela 15706, Spain
| | - José Castillo
- Clinical Neurosciences Research Laboratory, Health Research Institute of Santiago de Compostela (IDIS), Santiago de Compostela 15706, Spain
| | - Pablo Aguiar
- Molecular Imaging Research Group, Nuclear Medicine Department, Health Research Institute of Santiago de Compostela (IDIS), Santiago de Compostela 15706, Spain.,Molecular Imaging and Medical Physics Group, Psychiatry, Radiology, Public Health, Nursing and Medicine Department, University of Santiago de Compostela (USC), University Clinical Hospital, Santiago de Compostela 15706, Spain
| | - Tomás Sobrino
- Clinical Neurosciences Research Laboratory, Health Research Institute of Santiago de Compostela (IDIS), Santiago de Compostela 15706, Spain
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5
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Gwak DS, Park HK, Jung C, Kim JH, Lee J, Kim BJ, Han MK, Bae HJ. Infarct growth patterns may vary in acute stroke due to large vessel occlusion and recanalization with endovascular therapy. Eur Radiol 2020; 30:6432-6440. [PMID: 32676782 DOI: 10.1007/s00330-020-07068-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 04/27/2020] [Accepted: 07/03/2020] [Indexed: 10/23/2022]
Abstract
OBJECTIVES This study aimed to investigate infarct growth patterns in stroke patients with large vessel occlusion (LVO) and successful recanalization by endovascular therapy (EVT). METHODS A total of 135 patients with LVO of the internal carotid artery or proximal segment of the middle cerebral artery admitted within 12 h after onset, having baseline National Institute of Health Stroke Scale score ≥ 5 points, and successfully recanalized by EVT were enrolled. Infarct growth pattern models were developed based on infarct volumes on diffusion-weighted imaging before and after reperfusion. Single pattern models of linear, logarithmic, and exponential shapes were initially tested. Their appropriateness was predetermined. If none of these patterns was suitable, the best pattern model, which was the most suitable pattern among the three shapes selected for each individual, was tested. Clinical correlates were explored. RESULTS Each single pattern model was tested for their suitability. However, none of the single pattern models successfully represented infarct growth curves: Of all subjects, only 63.7%, 62.2%, and 54.1% of patients were explained by the logarithmic, linear, and exponential model, respectively. Compared with the single pattern models, the best pattern model explained 80.7% of the subjects. The linear shape fit best in 40 patients, the logarithmic in 51, and the exponential in 44. Those fit best for the logarithmic pattern showed more favorable outcomes at discharge (31.4%) than did the others (linear, 10.0%; exponential, 9.1%; p = 0.01). CONCLUSIONS Infarct growth patterns may vary among individual patients with acute stroke due to LVO and successful treatment with EVT. KEY POINTS • Infarct growth during the acute stage of stroke is highly dynamic and the exact shape remains unknown. • Infarct growth pattern models were developed based on infarct volumes on diffusion-weighted imaging before and after reperfusion. • Infarct growth patterns may not be singular, rather various among individual patients with acute stroke due to LVO and successful treatment with EVT.
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Affiliation(s)
- Dong-Seok Gwak
- Department of Neurology, Kyungpook National University Hospital, Daegu, South Korea
| | - Hong-Kyun Park
- Department of Neurology, Inje University Ilsan Paik Hospital, Inje University College of Medicine, Goyang, South Korea
| | - Cheolkyu Jung
- Department of Radiology, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, South Korea
| | - Jae Hyoung Kim
- Department of Radiology, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, South Korea
| | - Juneyoung Lee
- Department of Biostatistics, Korea University College of Medicine, Seoul, South Korea
| | - Beom Joon Kim
- Department of Neurology, Seoul National University Bundang Hospital, Seoul National University College of Medicine, 82, Gumi-ro 173 beon-gil, Bundang-gu, Seongnam-si, Gyeonggi-do, 13620, South Korea
| | - Moon-Ku Han
- Department of Neurology, Seoul National University Bundang Hospital, Seoul National University College of Medicine, 82, Gumi-ro 173 beon-gil, Bundang-gu, Seongnam-si, Gyeonggi-do, 13620, South Korea
| | - Hee-Joon Bae
- Department of Neurology, Seoul National University Bundang Hospital, Seoul National University College of Medicine, 82, Gumi-ro 173 beon-gil, Bundang-gu, Seongnam-si, Gyeonggi-do, 13620, South Korea.
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6
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Response of distant regions affected by diaschisis commissuralis in one of the most common models of transient focal ischemia in rats. J Chem Neuroanat 2019; 101:101666. [DOI: 10.1016/j.jchemneu.2019.101666] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 08/09/2019] [Accepted: 08/10/2019] [Indexed: 11/17/2022]
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7
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Jiang B, Ball RL, Michel P, Li Y, Zhu G, Ding V, Su B, Naqvi Z, Eskandari A, Desai M, Wintermark M. Factors influencing infarct growth including collateral status assessed using computed tomography in acute stroke patients with large artery occlusion. Int J Stroke 2019; 14:603-612. [PMID: 31096871 DOI: 10.1177/1747493019851278] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
In major ischemic stroke caused by a large artery occlusion, neuronal loss varies considerably across individuals without revascularization. This study aims to identify which patient characteristics are most highly associated with this variability. Demographic and clinical information were retrospectively collected on a registry of 878 patients. Imaging biomarkers including Alberta Stroke Program Early CT score, noncontrast head computed tomography infarct volume, perfusion computed tomography infarct core and penumbra, occlusion site, collateral score, and recanalization status were evaluated on the baseline and early follow-up computed tomography images. Infarct growth rates were calculated by dividing infarct volumes by the time elapsed between the computed tomography scan and the symptom onset. Collateral score was graded into four levels (0, 1, 2, and 3) in comparison with the normal side. Correlation of perfusion computed tomography and noncontrast head computed tomography infarct volumes and infarct growth rates were estimated with the nonparametric Spearman's rank correlation. Conditional inference trees were used to identify the clinical and imaging biomarkers that were most highly associated with the infarct growth rate and modified Rankin Scale at 90 days. Two hundred and thirty-two patients met the inclusion criteria for this study. The median infarct growth rates for perfusion computed tomography and noncontrast head computed tomography were 11.2 and 6.2 ml/log(min) in logarithmic model, and 18.9 and 10.4 ml/h in linear model, respectively. Noncontrast head computed tomography and perfusion computed tomography infarct volumes and infarct growth rates were significantly correlated (rho=0.53; P < 0.001). Collateral status was the strongest predictor for infarct growth rates. For collateral=0, the perfusion computed tomography and noncontrast head computed tomography infarct growth rate were 31.56 and 16.86 ml/log(min), respectively. Patients who had collateral >0 and penumbra volumes>92 ml had the lowest predicted perfusion computed tomography infarct growth rates (6.61 ml/log(min)). Collateral status was closely related to the diversity of infarct growth rates, poor collaterals were associated with a faster infarct growth rates and vice versa.
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Affiliation(s)
- Bin Jiang
- 1 Department of Radiology, Neuroradiology Section, Stanford University School of Medicine, Stanford, USA
| | - Robyn L Ball
- 2 Department of Medicine, Quantitative Sciences Unit, Stanford University, Stanford, USA
| | - Patrik Michel
- 3 Department of Neurology, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
| | - Ying Li
- 1 Department of Radiology, Neuroradiology Section, Stanford University School of Medicine, Stanford, USA
| | - Guangming Zhu
- 1 Department of Radiology, Neuroradiology Section, Stanford University School of Medicine, Stanford, USA
| | - Victoria Ding
- 2 Department of Medicine, Quantitative Sciences Unit, Stanford University, Stanford, USA
| | - Bochao Su
- 1 Department of Radiology, Neuroradiology Section, Stanford University School of Medicine, Stanford, USA
| | - Zack Naqvi
- 1 Department of Radiology, Neuroradiology Section, Stanford University School of Medicine, Stanford, USA
| | - Ashraf Eskandari
- 3 Department of Neurology, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
| | - Manisha Desai
- 2 Department of Medicine, Quantitative Sciences Unit, Stanford University, Stanford, USA
| | - Max Wintermark
- 1 Department of Radiology, Neuroradiology Section, Stanford University School of Medicine, Stanford, USA
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8
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Bonnitcha P, Grieve S, Figtree G. Clinical imaging of hypoxia: Current status and future directions. Free Radic Biol Med 2018; 126:296-312. [PMID: 30130569 DOI: 10.1016/j.freeradbiomed.2018.08.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 07/30/2018] [Accepted: 08/14/2018] [Indexed: 12/20/2022]
Abstract
Tissue hypoxia is a key feature of many important causes of morbidity and mortality. In pathologies such as stroke, peripheral vascular disease and ischaemic heart disease, hypoxia is largely a consequence of low blood flow induced ischaemia, hence perfusion imaging is often used as a surrogate for hypoxia to guide clinical diagnosis and treatment. Importantly, ischaemia and hypoxia are not synonymous conditions as it is not universally true that well perfused tissues are normoxic or that poorly perfused tissues are hypoxic. In pathologies such as cancer, for instance, perfusion imaging and oxygen concentration are less well correlated, and oxygen concentration is independently correlated to radiotherapy response and overall treatment outcomes. In addition, the progression of many diseases is intricately related to maladaptive responses to the hypoxia itself. Thus there is potentially great clinical and scientific utility in direct measurements of tissue oxygenation. Despite this, imaging assessment of hypoxia in patients is rarely performed in clinical settings. This review summarises some of the current methods used to clinically evaluate hypoxia, the barriers to the routine use of these methods and the newer agents and techniques being explored for the assessment of hypoxia in pathological processes.
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Affiliation(s)
- Paul Bonnitcha
- Northern and Central Clinical Schools, Faculty of Medicine, Sydney University, Sydney, NSW 2006, Australia; Chemical Pathology Department, NSW Health Pathology, Royal Prince Alfred Hospital, Camperdown, NSW 2050, Australia; Kolling Institute of Medical Research, University of Sydney, St Leonards, New South Wales 2065, Australia.
| | - Stuart Grieve
- Sydney Translational Imaging Laboratory, Heart Research Institute, Charles Perkins Centre and Sydney Medical School, University of Sydney, NSW 2050, Australia
| | - Gemma Figtree
- Kolling Institute of Medical Research, University of Sydney, St Leonards, New South Wales 2065, Australia; Cardiology Department, Royal North Shore Hospital, St Leonards, New South Wales 2065, Australia
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9
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Leigh R, Knutsson L, Zhou J, van Zijl PC. Imaging the physiological evolution of the ischemic penumbra in acute ischemic stroke. J Cereb Blood Flow Metab 2018; 38:1500-1516. [PMID: 28345479 PMCID: PMC6125975 DOI: 10.1177/0271678x17700913] [Citation(s) in RCA: 98] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We review the hemodynamic, metabolic and cellular parameters affected during early ischemia and their changes as a function of approximate cerebral blood flow ( CBF) thresholds. These parameters underlie the current practical definition of an ischemic penumbra, namely metabolically affected but still viable brain tissue. Such tissue is at risk of infarction under continuing conditions of reduced CBF, but can be rescued through timely intervention. This definition will be useful in clinical diagnosis only if imaging techniques exist that can rapidly, and with sufficient accuracy, visualize the existence of a mismatch between such a metabolically affected area and regions that have suffered cell depolarization. Unfortunately, clinical data show that defining the outer boundary of the penumbra based solely on perfusion-related thresholds may not be sufficiently accurate. Also, thresholds for CBF and cerebral blood volume ( CBV) differ for white and gray matter and evolve with time for both inner and outer penumbral boundaries. As such, practical penumbral imaging would involve parameters in which the physiology is immediately displayed in a manner independent of baseline CBF or CBF threshold, namely pH, oxygen extraction fraction ( OEF), diffusion constant and mean transit time ( MTT). Suitable imaging technologies will need to meet this requirement in a 10-20 min exam.
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Affiliation(s)
- Richard Leigh
- 1 National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, USA
| | - Linda Knutsson
- 2 Department of Medical Radiation Physics, Lund University, Lund, Sweden.,3 Department of Radiology, Johns Hopkins University, Baltimore, MD, USA
| | - Jinyuan Zhou
- 3 Department of Radiology, Johns Hopkins University, Baltimore, MD, USA.,4 F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
| | - Peter Cm van Zijl
- 3 Department of Radiology, Johns Hopkins University, Baltimore, MD, USA.,4 F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
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10
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Gomez CR. Time Is Brain: The Stroke Theory of Relativity. J Stroke Cerebrovasc Dis 2018; 27:2214-2227. [DOI: 10.1016/j.jstrokecerebrovasdis.2018.04.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 04/04/2018] [Indexed: 01/24/2023] Open
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11
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Salas JR, Chen BY, Wong A, Duarte S, Angarita SAK, Lipshutz GS, Witte ON, Clark PM. Noninvasive Imaging of Drug-Induced Liver Injury with 18F-DFA PET. J Nucl Med 2018; 59:1308-1315. [PMID: 29496991 PMCID: PMC6071498 DOI: 10.2967/jnumed.117.206961] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 02/21/2018] [Indexed: 12/19/2022] Open
Abstract
Drug-induced liver failure is a significant indication for a liver transplant, and unexpected liver toxicity is a major reason that otherwise effective therapies are removed from the market. Various methods exist for monitoring liver injury but are often inadequate to predict liver failure. New diagnostic tools are needed. Methods: We evaluate in a preclinical model whether 18F-2-deoxy-2-fluoroarabinose (18F-DFA), a PET radiotracer that measures the ribose salvage pathway, can be used to monitor acetaminophen-induced liver injury and failure. Mice treated with vehicle, 100, 300, or 500 mg/kg acetaminophen for 7 or 21 h were imaged with 18F-FDG and 18F-DFA PET. Hepatic radiotracer accumulation was correlated to survival and percentage of nonnecrotic tissue in the liver. Mice treated with acetaminophen and vehicle or N-acetylcysteine were imaged with 18F-DFA PET. 18F-DFA accumulation was evaluated in human hepatocytes engrafted into the mouse liver. Results: We show that hepatic 18F-DFA accumulation is 49%-52% lower in mice treated with high-dose acetaminophen than in mice treated with low-dose acetaminophen or vehicle. Under these same conditions, hepatic 18F-FDG accumulation was unaffected. At 21 h after acetaminophen treatment, hepatic 18F-DFA accumulation can distinguish mice that will succumb to the liver injury from those that will survive it (6.2 vs. 9.7 signal to background, respectively). Hepatic 18F-DFA accumulation in this model provides a tomographic representation of hepatocyte density in the liver, with a R2 between hepatic 18F-DFA accumulation and percentage of nonnecrotic tissue of 0.70. PET imaging with 18F-DFA can be used to distinguish effective from ineffective resolution of acetaminophen-induced liver injury with N-acetylcysteine (15.6 vs. 6.2 signal to background, respectively). Human hepatocytes, in culture or engrafted into a mouse liver, have levels of ribose salvage activity similar to those of mouse hepatocytes. Conclusion: Our findings suggest that PET imaging with 18F-DFA can be used to visualize and quantify drug-induced acute liver injury and may provide information on the progression from liver injury to hepatic failure.
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Affiliation(s)
- Jessica R Salas
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles California
- Crump Institute for Molecular Imaging, University of California, Los Angeles California
| | - Bao Ying Chen
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles California
- Crump Institute for Molecular Imaging, University of California, Los Angeles California
| | - Alicia Wong
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles California
- Crump Institute for Molecular Imaging, University of California, Los Angeles California
| | - Sergio Duarte
- Department of Surgery, University of California, Los Angeles California
| | | | - Gerald S Lipshutz
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles California
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California, Los Angeles California
- Intellectual and Developmental Disabilities Research Center, University of California, Los Angeles California; and
| | - Owen N Witte
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles California
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California, Los Angeles California
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles California
| | - Peter M Clark
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles California
- Crump Institute for Molecular Imaging, University of California, Los Angeles California
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California, Los Angeles California
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12
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Thirugnanachandran T, Ma H, Singhal S, Slater LA, Davis SM, Donnan GA, Phan T. Refining the ischemic penumbra with topography. Int J Stroke 2017; 13:277-284. [DOI: 10.1177/1747493017743056] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
It has been 40 years since the ischemic penumbra was first conceptualized through work on animal models. The topography of penumbra has been portrayed as an infarcted core surrounded by penumbral tissue and an extreme rim of oligemic tissue. This picture has been used in many review articles and textbooks before the advent of modern imaging. In this paper, we review our understanding of the topography of the ischemic penumbra from the initial experimental animal models to current developments with neuroimaging which have helped to further define the temporal and spatial evolution of the penumbra and refine our knowledge. The concept of the penumbra has been successfully applied in clinical trials of endovascular therapies with a time window as long as 24 h from onset. Further, there are reports of “good” outcome even in patients with a large ischemic core. This latter observation of good outcome despite having a large core requires an understanding of the topography of the penumbra and the function of the infarcted regions. It is proposed that future research in this area takes departure from a time-dependent approach to a more individualized tissue and location-based approach.
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Affiliation(s)
- Tharani Thirugnanachandran
- Stroke & Ageing Research (STARC), Department of Medicine, School of Clinical Sciences at Monash Health, Monash University, Clayton, VIC, Australia
| | - Henry Ma
- Stroke & Ageing Research (STARC), Department of Medicine, School of Clinical Sciences at Monash Health, Monash University, Clayton, VIC, Australia
| | - Shaloo Singhal
- Stroke & Ageing Research (STARC), Department of Medicine, School of Clinical Sciences at Monash Health, Monash University, Clayton, VIC, Australia
| | - Lee-Anne Slater
- Diagnostic Imaging, Monash Health, The Royal Melbourne Hospital and the University of Melbourne, Parkville, VIC, Australia
| | - Stephen M Davis
- Melbourne Brain Centre, The Royal Melbourne Hospital and the University of Melbourne, Parkville, VIC, Australia
| | - Geoffrey A Donnan
- Florey Neuroscience Institute, The Royal Melbourne Hospital and the University of Melbourne, Parkville, VIC, Australia
| | - Thanh Phan
- Stroke & Ageing Research (STARC), Department of Medicine, School of Clinical Sciences at Monash Health, Monash University, Clayton, VIC, Australia
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13
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Effects of hyperoxia on 18F-fluoro-misonidazole brain uptake and tissue oxygen tension following middle cerebral artery occlusion in rodents: Pilot studies. PLoS One 2017; 12:e0187087. [PMID: 29091934 PMCID: PMC5665507 DOI: 10.1371/journal.pone.0187087] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2017] [Accepted: 10/15/2017] [Indexed: 12/11/2022] Open
Abstract
PURPOSE Mapping brain hypoxia is a major goal for stroke diagnosis, pathophysiology and treatment monitoring. 18F-fluoro-misonidazole (FMISO) positron emission tomography (PET) is the gold standard hypoxia imaging method. Normobaric hyperoxia (NBO) is a promising therapy in acute stroke. In this pilot study, we tested the straightforward hypothesis that NBO would markedly reduce FMISO uptake in ischemic brain in Wistar and spontaneously hypertensive rats (SHRs), two rat strains with distinct vulnerability to brain ischemia, mimicking clinical heterogeneity. METHODS Thirteen adult male rats were randomized to distal middle cerebral artery occlusion under either 30% O2 or 100% O2. FMISO was administered intravenously and PET data acquired dynamically for 3hrs, after which magnetic resonance imaging (MRI) and tetrazolium chloride (TTC) staining were carried out to map the ischemic lesion. Both FMISO tissue uptake at 2-3hrs and FMISO kinetic rate constants, determined based on previously published kinetic modelling, were obtained for the hypoxic area. In a separate group (n = 9), tissue oxygen partial pressure (PtO2) was measured in the ischemic tissue during both control and NBO conditions. RESULTS As expected, the FMISO PET, MRI and TTC lesion volumes were much larger in SHRs than Wistar rats in both the control and NBO conditions. NBO did not appear to substantially reduce FMISO lesion size, nor affect the FMISO kinetic rate constants in either strain. Likewise, MRI and TTC lesion volumes were unaffected. The parallel study showed the expected increases in ischemic cortex PtO2 under NBO, although these were small in some SHRs with very low baseline PtO2. CONCLUSIONS Despite small samples, the apparent lack of marked effects of NBO on FMISO uptake suggests that in permanent ischemia the cellular mechanisms underlying FMISO trapping in hypoxic cells may be disjointed from PtO2. Better understanding of FMISO trapping processes will be important for future applications of FMISO imaging.
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14
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Evans NR, Tarkin JM, Buscombe JR, Markus HS, Rudd JHF, Warburton EA. PET imaging of the neurovascular interface in cerebrovascular disease. Nat Rev Neurol 2017; 13:676-688. [PMID: 28984315 DOI: 10.1038/nrneurol.2017.129] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Cerebrovascular disease encompasses a range of pathologies that affect different components of the cerebral vasculature and brain parenchyma. Large artery atherosclerosis, acute cerebral ischaemia, and intracerebral small vessel disease all demonstrate altered metabolic processes that are key to their pathogenesis. Although structural imaging techniques such as MRI are the mainstay of clinical care and research in cerebrovascular disease, they have limited ability to detect these pathophysiological processes in vivo. By contrast, PET can detect and quantify metabolic processes that are relevant to each facet of cerebrovascular disease. Information obtained from PET studies has helped to shape the understanding of key concepts in cerebrovascular medicine, including vulnerable atherosclerotic plaque, salvageable ischaemic penumbra, neuroinflammation and selective neuronal loss after ischaemic insult. PET has also helped to elucidate the relationships between chronic hypoxia, neuroinflammation, and amyloid-β deposition in cerebral small vessel disease. This Review describes how PET-based imaging of metabolic processes at the neurovascular interface has contributed to our understanding of cerebrovascular disease.
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Affiliation(s)
- Nicholas R Evans
- Department of Clinical Neurosciences, University of Cambridge, Box 83, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, UK
| | - Jason M Tarkin
- Division of Cardiovascular Medicine, Department of Medicine, University of Cambridge, Box 157, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, UK
| | - John R Buscombe
- Department of Nuclear Medicine, Box 219, Cambridge University Hospitals NHS Foundation Trust, Hills Road, Cambridge CB2 0QQ, UK
| | - Hugh S Markus
- Department of Clinical Neurosciences, University of Cambridge, Box 83, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, UK
| | - James H F Rudd
- Division of Cardiovascular Medicine, Department of Medicine, University of Cambridge, Box 157, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, UK
| | - Elizabeth A Warburton
- Department of Clinical Neurosciences, University of Cambridge, Box 83, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, UK
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15
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Yang W, Paschen W. Is age a key factor contributing to the disparity between success of neuroprotective strategies in young animals and limited success in elderly stroke patients? Focus on protein homeostasis. J Cereb Blood Flow Metab 2017; 37:3318-3324. [PMID: 28752781 PMCID: PMC5624400 DOI: 10.1177/0271678x17723783] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Neuroprotection strategies to improve stroke outcome have been successful in the laboratory but not in clinical stroke trials, and thus have come under scrutiny by the medical community. Experimental stroke investigators are therefore under increased pressure to resolve this problem. Acute ischemic stroke represents a severe form of metabolic stress that activates many pathological processes and thereby impairs cellular functions. Traditionally, neuroprotection strategies were designed to improve stroke outcome by interfering with pathological processes triggered by ischemia. However, stroke outcome is also dependent on the brain's capacity to restore cellular functions impaired by ischemia, and this capacity declines with age. It is, therefore, conceivable that this age-dependent decline in the brain's self-healing capacity contributes to the disparity between the success of neuroprotective strategies in young animals, and limited success in elderly stroke patients. Here, prosurvival pathways that restore protein homeostasis impaired by ischemic stress should be considered, because their capacity decreases with increasing age, and maintenance of proteome fidelity is pivotal for cell survival. Boosting such prosurvival pathways pharmacologically to restore protein homeostasis and, thereby, cellular functions impaired by ischemic stress is expected to counterbalance the compromised self-healing capacity of aged brains and thereby help to improve stroke outcome.
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Affiliation(s)
- Wei Yang
- 1 Laboratory of Molecular Neurobiology, Multidisciplinary Neuroprotection Laboratories, Department of Anesthesiology, Duke University Medical Center, Durham, NC, USA
| | - Wulf Paschen
- 1 Laboratory of Molecular Neurobiology, Multidisciplinary Neuroprotection Laboratories, Department of Anesthesiology, Duke University Medical Center, Durham, NC, USA.,2 Department of Neurobiology, Duke University Medical Center, Durham, NC, USA
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16
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Gribkoff VK, Kaczmarek LK. The need for new approaches in CNS drug discovery: Why drugs have failed, and what can be done to improve outcomes. Neuropharmacology 2017; 120:11-19. [PMID: 26979921 PMCID: PMC5820030 DOI: 10.1016/j.neuropharm.2016.03.021] [Citation(s) in RCA: 210] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Revised: 02/14/2016] [Accepted: 03/11/2016] [Indexed: 12/31/2022]
Abstract
An important goal of biomedical research is to translate basic research findings into useful medical advances. In the field of neuropharmacology this requires understanding disease mechanisms as well as the effects of drugs and other compounds on neuronal function. Our hope is that this information will result in new or improved treatment for CNS disease. Despite great progress in our understanding of the structure and functions of the CNS, the discovery of new drugs and their clinical development for many CNS disorders has been problematic. As a result, CNS drug discovery and development programs have been subjected to significant cutbacks and eliminations over the last decade. While there has been recent resurgence of interest in CNS targets, these past changes in priority of the pharmaceutical and biotech industries reflect several well-documented realities. CNS drugs in general have higher failure rates than non-CNS drugs, both preclinically and clinically, and in some areas, such as the major neurodegenerative diseases, the clinical failure rate for disease-modifying treatments has been 100%. The development times for CNS drugs are significantly longer for those drugs that are approved, and post-development regulatory review is longer. In this introduction we review some of the reasons for failure, delineating both scientific and technical realities, some unique to the CNS, that have contributed to this. We will focus on major neurodegenerative disorders, which affect millions, attract most of the headlines, and yet have witnessed the fewest successes. We will suggest some changes that, when coupled with the approaches discussed in the rest of this special volume, may improve outcomes in future CNS-targeted drug discovery and development efforts. This article is part of the Special Issue entitled "Beyond small molecules for neurological disorders".
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Affiliation(s)
- Valentin K Gribkoff
- Department of Internal Medicine, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA.
| | - Leonard K Kaczmarek
- Department of Pharmacology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA; Department of Cellular and Molecular Physiology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
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17
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Schindler TH. Cardiovascular PET/MR imaging: Quo Vadis? J Nucl Cardiol 2017; 24:1007-1018. [PMID: 27659454 DOI: 10.1007/s12350-016-0451-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2016] [Accepted: 02/08/2016] [Indexed: 12/30/2022]
Abstract
With the recent advent of PET/MRI scanners, the combination of molecular imaging with a variety of known and novel PET radiotracers, the high spatial resolution of MRI, and its potential for multi-parametric imaging are anticipated to increase the diagnostic accuracy in cardiovascular disease detection, while providing novel mechanistic insights into the initiation and progression of the disease state. For the time being, cardiac PET/MRI emerges as potential clinical tool in the identification and characterization of infiltrative cardiac diseases, such as sarcoidosis, acute or chronic myocarditis, and cardiac tumors, respectively. The application of PET/MRI in conjunction with various radiotracer probes in the identification of the vulnerable atherosclerotic plaque also holds much promise but needs further translation and validation in clinical investigations. The combination of molecular imaging and creation of multi-parametric imaging maps with PET/MRI, however, are likely to set new horizons to develop predictive parameters for myocardial recovery and treatment response in ischemic and non-ischemic cardiomyopathy patients. Molecular imaging and multi-parametric imaging in cardiovascular disease with PET/MRI at current stage are at its infancy but bear a bright future.
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Affiliation(s)
- Thomas Hellmut Schindler
- Department of Radiology and Radiological Science, Division of Nuclear Medicine, Nuclear Cardiovascular Medicine, Johns Hopkins University School of Medicine, 3225, 601 N. Caroline Street, Baltimore, MD, 21287, USA.
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18
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Jensen-Kondering U, Manavaki R, Ejaz S, Sawiak SJ, Carpenter TA, Fryer TD, Aigbirhio FI, Williamson DJ, Baron JC. Brain hypoxia mapping in acute stroke: Back-to-back T2' MR versus 18F-fluoromisonidazole PET in rodents. Int J Stroke 2017; 12:752-760. [PMID: 28523963 DOI: 10.1177/1747493017706221] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Background Mapping the hypoxic brain in acute ischemic stroke has considerable potential for both diagnosis and treatment monitoring. PET using 18F-fluoro-misonidazole (FMISO) is the reference method; however, it lacks clinical accessibility and involves radiation exposure. MR-based T2' mapping may identify tissue hypoxia and holds clinical potential. However, its validation against FMISO imaging is lacking. Here we implemented back-to-back FMISO-PET and T2' MR in rodents subjected to acute middle cerebral artery occlusion. For direct clinical relevance, regions of interest delineating reduced T2' signal areas were manually drawn. Methods Wistar rats were subjected to filament middle cerebral artery occlusion, immediately followed by intravenous FMISO injection. Multi-echo T2 and T2* sequences were acquired twice during FMISO brain uptake, interleaved with diffusion-weighted imaging. Perfusion-weighted MR was also acquired whenever feasible. Immediately following MR, PET data reflecting the history of FMISO brain uptake during MR acquisition were acquired. T2' maps were generated voxel-wise from T2 and T2*. Two raters independently drew T2' lesion regions of interest. FMISO uptake and perfusion data were obtained within T2' consensus regions of interest, and their overlap with the automatically generated FMISO lesion and apparent diffusion coefficient lesion regions of interest was computed. Results As predicted, consensus T2' lesion regions of interest exhibited high FMISO uptake as well as substantial overlap with the FMISO lesion and significant hypoperfusion, but only small overlap with the apparent diffusion coefficient lesion. Overlap of the T2' lesion regions of interest between the two raters was ∼50%. Conclusions This study provides formal validation of T2' to map non-core hypoxic tissue in acute stroke. T2' lesion delineation reproducibility was suboptimal, reflecting unclear lesion borders.
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Affiliation(s)
- Ulf Jensen-Kondering
- 1 Stroke Research Group, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.,2 Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.,3 Department of Radiology and Neuroradiology, University Medical Center Schleswig-Holstein, Kiel, Germany
| | - Roido Manavaki
- 4 Department of Radiology, University of Cambridge, Cambridge, UK
| | - Sohail Ejaz
- 1 Stroke Research Group, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Stephen J Sawiak
- 2 Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - T Adrian Carpenter
- 2 Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Tim D Fryer
- 2 Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Franklin I Aigbirhio
- 2 Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - David J Williamson
- 2 Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Jean-Claude Baron
- 1 Stroke Research Group, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.,5 INSERM U894, Université Paris Descartes, Hôpital Sainte-Anne, Paris, France
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19
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Funck T, Al‐Kuwaiti M, Lepage C, Zepper P, Minuk J, Schipper HM, Evans AC, Thiel A. Assessing neuronal density in peri-infarct cortex with PET: Effects of cortical topology and partial volume correction. Hum Brain Mapp 2017; 38:326-338. [PMID: 27614005 PMCID: PMC6866936 DOI: 10.1002/hbm.23363] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 08/05/2016] [Accepted: 08/18/2016] [Indexed: 01/02/2023] Open
Abstract
The peri-infarct cortex (PIC) is the site of long-term physiologic changes after ischemic stroke. Traditional methods for delineating the peri-infarct gray matter (GM) have used a volumetric Euclidean distance metric to define its extent around the infarct. This metric has limitations in the case of cortical stroke, i.e., those where ischemia leads to infarction in the cortical GM, because the vascularization of the cerebral cortex follows the complex, folded topology of the cortical surface. Instead, we used a geodesic distance metric along the cortical surface to subdivide the PIC into equidistant rings emanating from the infarct border and compared this new approach to a Euclidean distance metric definition. This was done in 11 patients with [F-18]-Flumazenil ([18-F]-FMZ) positron emission tomography (PET) scans at 2 weeks post-stroke and at 6 month follow-up. FMZ is a PET radiotracer with specific binding to the alpha subunits of the type A γ-aminobutyric acid (GABAA) receptor. Additionally, we used partial-volume correction (PVC) of the PET images to compensate for potential cortical thinning and long-term neuronal loss in follow-up images. The difference in non-displaceable binding potential (BPND ) between the stroke unaffected and affected hemispheres was 35% larger in the geodesic versus the Euclidean peri-infarct models in initial PET images and 48% larger in follow-up PET images. The inter-hemispheric BPND difference was approximately 17-20% larger after PVC when compared to uncorrected PET images. PET studies of peri-infarct GM in cortical strokes should use a geodesic model and include PVC as a preprocessing step. Hum Brain Mapp 38:326-338, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Thomas Funck
- Montreal Neurological Institute, McGill UniversityMontrealCanada
- Jewish General HospitalLady Davis InstituteMontrealCanada
| | - Mohammed Al‐Kuwaiti
- Montreal Neurological Institute, McGill UniversityMontrealCanada
- Jewish General HospitalLady Davis InstituteMontrealCanada
| | - Claude Lepage
- Montreal Neurological Institute, McGill UniversityMontrealCanada
| | - Peter Zepper
- Department of NeurologyTechnische Universität MünchenMunichGermany
| | - Jeffrey Minuk
- Jewish General HospitalLady Davis InstituteMontrealCanada
| | | | - Alan C. Evans
- Montreal Neurological Institute, McGill UniversityMontrealCanada
| | - Alexander Thiel
- Montreal Neurological Institute, McGill UniversityMontrealCanada
- Jewish General HospitalLady Davis InstituteMontrealCanada
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20
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Christoforidis GA, Vakil P, Ansari SA, Dehkordi FH, Carroll TJ. Impact of Pial Collaterals on Infarct Growth Rate in Experimental Acute Ischemic Stroke. AJNR Am J Neuroradiol 2016; 38:270-275. [PMID: 27856435 DOI: 10.3174/ajnr.a5003] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 09/06/2016] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Cerebral infarction evolves at different rates depending on available blood flow suggesting that treatment time windows vary depending on the degree of pial collateral recruitment. This work sought to mathematically model infarct growth and determine whether infarct volume growth can be predicted by angiographic assessment of pial collateral recruitment in an experimental MCA occlusion animal model. MATERIALS AND METHODS Pial collateral recruitment was quantified by using DSA, acquired 15 minutes following permanent MCA occlusion in 6 canines based on a scoring system (average pial collateral score) and arterial arrival time. MR imaging-based infarct volumes were measured 60, 90, 120, 180, 240 and 1440 minutes following MCA occlusion and were parameterized in terms of the growth rate index and final infarct volume (VFinal) as V(t) = VFinal [1 - e(-G × t)] (t = time). Correlations of the growth rate index and final infarct volume to the average pial collateral score and arterial arrival time were assessed by linear bivariate analysis. Correlations were used to generate asymptotic models of infarct growth for average pial collateral score or arterial arrival time values. Average pial collateral score- and arterial arrival time-based models were assessed by F tests and residual errors. RESULTS Evaluation of pial collateral recruitment at 15 minutes postocclusion was strongly correlated with 24-hour infarct volumes (average pial collateral score: r2 = 0.96, P < .003; arterial arrival time: r2 = 0.86, P < .008). Infarct growth and the growth rate index had strong and moderate linear relationships to the average pial collateral score (r2 = 0.89; P < .0033) and arterial arrival time (r2 = 0.69; P < .0419), respectively. Final infarct volume and the growth rate index were algebraically replaced by angiographically based collateral assessments to model infarct growth. The F test demonstrated no statistical advantage to using the average pial collateral score- over arterial arrival time-based predictive models, despite lower residual errors in the average pial collateral score-based model (P < .03). CONCLUSIONS In an experimental permanent MCA occlusion model, assessment of pial collaterals correlates with the infarct growth rate index and has the potential to predict asymptotic infarct volume growth.
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Affiliation(s)
- G A Christoforidis
- From the Department of Radiology (G.A.C., S.A.A., T.J.C.), University of Chicago, Chicago, Illinois
| | - P Vakil
- College of Medicine (P.V.), University of Illinois, Chicago, Illinois
| | - S A Ansari
- From the Department of Radiology (G.A.C., S.A.A., T.J.C.), University of Chicago, Chicago, Illinois.,Departments of Radiology, Neurology, and Neurological Surgery (S.A.A.), Northwestern University, Chicago, Illinois
| | - F H Dehkordi
- Department of Economics and Decision Sciences (F.H.D.), Western Illinois University, Macomb, Illinois
| | - T J Carroll
- From the Department of Radiology (G.A.C., S.A.A., T.J.C.), University of Chicago, Chicago, Illinois
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21
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Khaw AV, Angermaier A, Michel P, Kirsch M, Kessler C, Langner S. Inter-rater Agreement in Three Perfusion-Computed Tomography Evaluation Methods before Endovascular Therapy for Acute Ischemic Stroke. J Stroke Cerebrovasc Dis 2016; 25:960-8. [PMID: 26851212 DOI: 10.1016/j.jstrokecerebrovasdis.2016.01.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Revised: 10/26/2015] [Accepted: 01/02/2016] [Indexed: 11/29/2022] Open
Abstract
PURPOSE There is ongoing debate on which method of perfusion computed tomography (PCT) evaluation in ischemic stroke is the most appropriate for improved selection of patients for endovascular treatment. We sought to test different assessment methods for inter-rater reliability. METHODS Twenty-six patients were enrolled prospectively before endovascular therapy for acute anterior circulation ischemic stroke. Three raters experienced in stroke imaging and blinded to other imaging and clinical information independently analyzed 22 technically successful PCT scans according to 3 prespecified assessment methods applied to cerebral blood flow (CBF)/cerebral blood volume (CBV) and time-to-peak (TTP) maps: (1) visual mismatch estimate (VME), (2) Alberta Stroke Program Early CT Score perfusion method (ASPECTS-PCT), and (3) quantitative perfusion ratios (qPRs): RCBF, RCBV, RTTP. Inter-rater agreement was assessed with Cohen's kappa, intraclass correlation coefficients (ICC), Bland-Altman plots, and global and descriptive statistics. RESULTS Significant differences between raters were found with VME and ASPECTS-PCT (P < .001) but with qPRs only for CBV (P = .03). Inter-rater agreement for VME was at best moderate by kappa statistics (.51); moderate by ICC for all parametric maps of ASPECTS-PCT (.56-.62), strong for RTTP (.76), and excellent for RCBF (.92) and RCBV (.86). Pairwise comparisons revealed less scattering of individual values with qPRs and less deviation of mean differences from 0, suggesting minor systematic deviation by any 1 rater as compared with VME or ASPECTS-PCT. CONCLUSION PCT evaluation methods used before endovascular therapy for acute anterior circulation stroke are subject to substantial inter-rater disagreement. QPRs in PCT evaluation had better inter-rater reliability than the often used VME and ASPECTS-PCT assessment.
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Affiliation(s)
- A V Khaw
- Department of Clinical Neurosciences, University of Western Ontario, London Health Sciences Centre, London, Ontario, Canada
| | - A Angermaier
- Department of Neurology, University Medicine Greifswald, Greifswald, Germany
| | - P Michel
- Stroke Center, Department of Clinical Neurosciences, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
| | - M Kirsch
- Institute for Diagnostic Radiology and Neuroradiology, University Medicine Greifswald, Greifswald, Germany
| | - C Kessler
- Department of Neurology, University Medicine Greifswald, Greifswald, Germany
| | - S Langner
- Institute for Diagnostic Radiology and Neuroradiology, University Medicine Greifswald, Greifswald, Germany.
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22
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Beard DJ, McLeod DD, Logan CL, Murtha LA, Imtiaz MS, van Helden DF, Spratt NJ. Intracranial pressure elevation reduces flow through collateral vessels and the penetrating arterioles they supply. A possible explanation for 'collateral failure' and infarct expansion after ischemic stroke. J Cereb Blood Flow Metab 2015; 35:861-72. [PMID: 25669909 PMCID: PMC4420869 DOI: 10.1038/jcbfm.2015.2] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Revised: 12/22/2014] [Accepted: 12/27/2014] [Indexed: 01/09/2023]
Abstract
Recent human imaging studies indicate that reduced blood flow through pial collateral vessels ('collateral failure') is associated with late infarct expansion despite stable arterial occlusion. The cause for 'collateral failure' is unknown. We recently showed that intracranial pressure (ICP) rises dramatically but transiently 24 hours after even minor experimental stroke. We hypothesized that ICP elevation would reduce collateral blood flow. First, we investigated the regulation of flow through collateral vessels and the penetrating arterioles arising from them during stroke reperfusion. Wistar rats were subjected to intraluminal middle cerebral artery (MCA) occlusion (MCAo). Individual pial collateral and associated penetrating arteriole blood flow was quantified using fluorescent microspheres. Baseline bidirectional flow changed to MCA-directed flow and increased by >450% immediately after MCAo. Collateral diameter changed minimally. Second, we determined the effect of ICP elevation on collateral and watershed penetrating arteriole flow. Intracranial pressure was artificially raised in stepwise increments during MCAo. The ICP increase was strongly correlated with collateral and penetrating arteriole flow reductions. Changes in collateral flow post-stroke appear to be primarily driven by the pressure drop across the collateral vessel, not vessel diameter. The ICP elevation reduces cerebral perfusion pressure and collateral flow, and is the possible explanation for 'collateral failure' in stroke-in-progression.
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Affiliation(s)
- Daniel J Beard
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, New South Wales, Australia
| | - Damian D McLeod
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, New South Wales, Australia
| | - Caitlin L Logan
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, New South Wales, Australia
| | - Lucy A Murtha
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, New South Wales, Australia
| | - Mohammad S Imtiaz
- 1] School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, New South Wales, Australia [2] Computational Cardiology Laboratory, Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia
| | - Dirk F van Helden
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, New South Wales, Australia
| | - Neil J Spratt
- 1] School of Biomedical Sciences and Pharmacy, University of Newcastle and Hunter Medical Research Institute, Callaghan, New South Wales, Australia [2] Department of Neurology, John Hunter Hospital, Hunter New England Local Health District, New Lambton Heights, New South Wales, Australia
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Saura H, Ogasawara K, Beppu T, Yoshida K, Kobayashi M, Yoshida K, Terasaki K, Takai Y, Ogawa A. Hypoxic viable tissue in human chronic cerebral ischemia because of unilateral major cerebral artery steno-occlusive disease. Stroke 2015; 46:1250-6. [PMID: 25873597 DOI: 10.1161/strokeaha.114.008238] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 03/16/2015] [Indexed: 01/07/2023]
Abstract
BACKGROUND AND PURPOSE Positron emission tomography (PET) with radiolabeled 2-nitroimidazoles directly detects hypoxic but viable tissue present in an acute ischemic area in the human brain. This study using PET with 1-(2-(18)F-fluoro-1-[hydroxymethyl]ethoxy) methyl-2-nitroimidazole ((18)F-FRP170) aimed to determine whether tissue with an abnormally elevated uptake of (18)F-FRP170 exists in human chronic cerebral ischemia because of unilateral atherosclerotic major cerebral artery steno-occlusive disease. METHODS (18)F-FRP170 PET was performed, and cerebral blood flow and metabolism were assessed using (15)O-gas PET in 20 healthy subjects and 52 patients. A region of interest (ROI) was automatically placed in 3 segments of the middle cerebral artery territory in both cerebral hemispheres with a 3-dimensional stereotaxic ROI template using SPM2, and each PET value was determined in each ROI. The ratio of values in the affected versus contralateral hemispheres was calculated for the (18)F-FRP170 PET image. RESULTS A significant correlation was observed between oxygen extraction fraction and (18)F-FRP170 ratios (ρ=0.509; P<0.0001) in a total of 156 ROIs in 52 patients. The specificity and positive-predictive value for a combination of an elevated oxygen extraction fraction and a moderately reduced cerebral oxygen metabolism for detection of an abnormally elevated (18)F-FRP170 ratio (19 ROIs: 12%) were significantly greater than those for the individual categories (elevated oxygen extraction fraction, moderately reduced cerebral oxygen metabolism, or reduced cerebral blood flow). CONCLUSIONS Tissues with abnormally elevated uptake of (18)F-FRP170 exist in human chronic cerebral ischemia characterized by a combination of misery perfusion and moderately reduced oxygen metabolism because of unilateral atherosclerotic major cerebral artery steno-occlusive disease.
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Affiliation(s)
- Hiroaki Saura
- From the Department of Neurosurgery (H.S., K.O., T.B., Koji Yoshida, M.K., Kenji Yoshida, A.O.) and Cyclotron Research Center (K.T.), School of Medicine, Iwate Medical University, Morioka, Japan; and Department of Radiology and Radiation Oncology, Hirosaki University Graduate School of Medicine, Hirosaki, Japan (Y.T.).
| | - Kuniaki Ogasawara
- From the Department of Neurosurgery (H.S., K.O., T.B., Koji Yoshida, M.K., Kenji Yoshida, A.O.) and Cyclotron Research Center (K.T.), School of Medicine, Iwate Medical University, Morioka, Japan; and Department of Radiology and Radiation Oncology, Hirosaki University Graduate School of Medicine, Hirosaki, Japan (Y.T.)
| | - Takaaki Beppu
- From the Department of Neurosurgery (H.S., K.O., T.B., Koji Yoshida, M.K., Kenji Yoshida, A.O.) and Cyclotron Research Center (K.T.), School of Medicine, Iwate Medical University, Morioka, Japan; and Department of Radiology and Radiation Oncology, Hirosaki University Graduate School of Medicine, Hirosaki, Japan (Y.T.)
| | - Koji Yoshida
- From the Department of Neurosurgery (H.S., K.O., T.B., Koji Yoshida, M.K., Kenji Yoshida, A.O.) and Cyclotron Research Center (K.T.), School of Medicine, Iwate Medical University, Morioka, Japan; and Department of Radiology and Radiation Oncology, Hirosaki University Graduate School of Medicine, Hirosaki, Japan (Y.T.)
| | - Masakazu Kobayashi
- From the Department of Neurosurgery (H.S., K.O., T.B., Koji Yoshida, M.K., Kenji Yoshida, A.O.) and Cyclotron Research Center (K.T.), School of Medicine, Iwate Medical University, Morioka, Japan; and Department of Radiology and Radiation Oncology, Hirosaki University Graduate School of Medicine, Hirosaki, Japan (Y.T.)
| | - Kenji Yoshida
- From the Department of Neurosurgery (H.S., K.O., T.B., Koji Yoshida, M.K., Kenji Yoshida, A.O.) and Cyclotron Research Center (K.T.), School of Medicine, Iwate Medical University, Morioka, Japan; and Department of Radiology and Radiation Oncology, Hirosaki University Graduate School of Medicine, Hirosaki, Japan (Y.T.)
| | - Kazunori Terasaki
- From the Department of Neurosurgery (H.S., K.O., T.B., Koji Yoshida, M.K., Kenji Yoshida, A.O.) and Cyclotron Research Center (K.T.), School of Medicine, Iwate Medical University, Morioka, Japan; and Department of Radiology and Radiation Oncology, Hirosaki University Graduate School of Medicine, Hirosaki, Japan (Y.T.)
| | - Yoshihiro Takai
- From the Department of Neurosurgery (H.S., K.O., T.B., Koji Yoshida, M.K., Kenji Yoshida, A.O.) and Cyclotron Research Center (K.T.), School of Medicine, Iwate Medical University, Morioka, Japan; and Department of Radiology and Radiation Oncology, Hirosaki University Graduate School of Medicine, Hirosaki, Japan (Y.T.)
| | - Akira Ogawa
- From the Department of Neurosurgery (H.S., K.O., T.B., Koji Yoshida, M.K., Kenji Yoshida, A.O.) and Cyclotron Research Center (K.T.), School of Medicine, Iwate Medical University, Morioka, Japan; and Department of Radiology and Radiation Oncology, Hirosaki University Graduate School of Medicine, Hirosaki, Japan (Y.T.)
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Tarkin JM, Joshi FR, Rajani NK, Rudd JHF. PET imaging of atherosclerosis. Future Cardiol 2015; 11:115-31. [DOI: 10.2217/fca.14.55] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
ABSTRACT Atherosclerosis is a chronic, progressive, multifocal disease of the arterial wall, which is mainly fuelled by local and systemic inflammation, often resulting in acute ischemic events following plaque rupture and vessel occlusion. When assessing the cardiovascular risk of an individual patient, we must consider both global measures of disease activity and local features of plaque vulnerability, in addition to anatomical distribution and degree of established atherosclerosis. These parameters cannot be measured with conventional anatomical imaging techniques alone, which are designed primarily to identify the presence of organic intraluminal obstruction in symptomatic patients. However, molecular imaging with PET, using specifically targeted radiolabeled probes to track active in vivo atherosclerotic mechanisms noninvasively, may potentially provide a method that is better suited for this purpose. Vascular PET imaging can help us to further understand aspects of plaque biology, and current evidence supports a future role as an emerging clinical tool for the quantification of cardiovascular risk in order to guide and monitor responses to antiatherosclerosis treatments and to distinguish high-risk plaques.
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Affiliation(s)
- Jason M Tarkin
- Division of Cardiovascular Medicine, University of Cambridge, Box 110, Addenbrooke's Centre for Clinical Investigation, Hills Road, Cambridge CB2 2QQ, UK
| | - Francis R Joshi
- Division of Cardiovascular Medicine, University of Cambridge, Box 110, Addenbrooke's Centre for Clinical Investigation, Hills Road, Cambridge CB2 2QQ, UK
| | - Nikil K Rajani
- Division of Cardiovascular Medicine, University of Cambridge, Box 110, Addenbrooke's Centre for Clinical Investigation, Hills Road, Cambridge CB2 2QQ, UK
| | - James HF Rudd
- Division of Cardiovascular Medicine, University of Cambridge, Box 110, Addenbrooke's Centre for Clinical Investigation, Hills Road, Cambridge CB2 2QQ, UK
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Lee GH, Kim JS, Oh SJ, Kang DW, Kim JS, Kwon SU. (18)F-fluoromisonidazole (FMISO) Positron Emission Tomography (PET) Predicts Early Infarct Growth in Patients with Acute Ischemic Stroke. J Neuroimaging 2014; 25:652-5. [PMID: 25311732 DOI: 10.1111/jon.12180] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 02/27/2014] [Accepted: 03/02/2014] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE (18) F-fluoromisonidazole (FMISO) positron emission tomography (PET) is used to image metabolically compromised but viable hypoxic tissue. We hypothesized that FMISO PET might predict early infarct growth in acute ischemic stroke patients with perfusion-diffusion mismatch in magnetic resonance imaging (MRI). METHODS We prospectively enrolled acute ischemic stroke patients who visited the emergency room within 48 hours after stroke onset and had perfusion-diffusion mismatch (>20%), as shown MRI. Infarct growth was defined as >20% increase of initial infarct volume or >5 mL in follow-up diffusion-weighted image 5 ± 2 days after stroke. The association between FMISO uptake and infarct growth was explored. RESULTS Of 19 enrolled patients, 10 (52.6%) showed increased FMISO uptake, with 8 of the latter showing infarct growth. None of the 9 patients who did not show FMISO uptake had infarct growth. FMISO uptake was significantly associated with infarct growth (Fisher's exact test; P < .01). FMISO PET scan had a sensitivity of 100% and a specificity of 82% (AUC = .909) in predicting infarct growth. CONCLUSIONS FMISO PET scan can predict early infarct growth in acute ischemic stroke patients with perfusion-diffusion mismatch in MRI.
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Affiliation(s)
- Gha-Hyun Lee
- Department of Neurology, Pusan National University Hospital, Pusan National University School of Medicine and Medical Research Institute, Busan, South Korea
| | - Jae Seung Kim
- Department of Nuclear Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea
| | - Seung Jun Oh
- Department of Nuclear Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea
| | - Dong-Wha Kang
- Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea
| | - Jong S Kim
- Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea
| | - Sun U Kwon
- Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea
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PET imaging in ischemic cerebrovascular disease: current status and future directions. Neurosci Bull 2014; 30:713-32. [PMID: 25138055 DOI: 10.1007/s12264-014-1463-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Accepted: 04/10/2014] [Indexed: 01/08/2023] Open
Abstract
Cerebrovascular diseases are caused by interruption or significant impairment of the blood supply to the brain, which leads to a cascade of metabolic and molecular alterations resulting in functional disturbance and morphological damage. These pathophysiological changes can be assessed by positron emission tomography (PET), which permits the regional measurement of physiological parameters and imaging of the distribution of molecular markers. PET has broadened our understanding of the flow and metabolic thresholds critical for the maintenance of brain function and morphology: in this application, PET has been essential in the transfer of the concept of the penumbra (tissue with perfusion below the functional threshold but above the threshold for the preservation of morphology) to clinical stroke and thereby has had great impact on developing treatment strategies. Radioligands for receptors can be used as early markers of irreversible neuronal damage and thereby can predict the size of the final infarcts; this is also important for decisions concerning invasive therapy in large ("malignant") infarctions. With PET investigations, the reserve capacity of blood supply to the brain can be tested in obstructive arteriosclerosis of the supplying arteries, and this again is essential for planning interventions. The effect of a stroke on the surrounding and contralateral primarily unaffected tissue can be investigated, and these results help to understand the symptoms caused by disturbances in functional networks. Chronic cerebrovascular disease causes vascular cognitive disorders, including vascular dementia. PET permits the detection of the metabolic disturbances responsible for cognitive impairment and dementia, and can differentiate vascular dementia from degenerative diseases. It may also help to understand the importance of neuroinflammation after stroke and its interaction with amyloid deposition in the development of dementia. Although the clinical application of PET investigations is limited, this technology had and still has a great impact on research into cerebrovascular diseases.
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Mateo J, Izquierdo-Garcia D, Badimon JJ, Fayad ZA, Fuster V. Noninvasive assessment of hypoxia in rabbit advanced atherosclerosis using ¹⁸F-fluoromisonidazole positron emission tomographic imaging. Circ Cardiovasc Imaging 2014; 7:312-20. [PMID: 24508668 DOI: 10.1161/circimaging.113.001084] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Hypoxia is an important microenvironmental factor influencing atherosclerosis progression by inducing foam-cell formation, metabolic adaptation of infiltrated macrophages, and plaque neovascularization. Therefore, imaging plaque hypoxia could serve as a marker of lesions at risk. METHODS AND RESULTS Advanced aortic atherosclerosis was induced in 18 rabbits by atherogenic diet and double balloon endothelial denudation. Animals underwent (18)F-fluoromisonidazole positron emission tomographic and (18)F-fluorodeoxyglucose positron emission tomographic imaging after 6 to 8 months (atherosclerosis induction) and 12 to 16 months (progression) of diet initiation. Four rabbits fed standard chow served as controls. Radiotracer uptake of the abdominal aorta was measured using standardized uptake values. After imaging, plaque hypoxia (pimonidazole), macrophages (RAM-11), neovessels (CD31), and hypoxia-inducible factor-1α were assessed by immunohistochemistry.(18)F-fluoromisonidazole uptake increased with time on diet (standardized uptake value mean, 0.10±0.01 in nonatherosclerotic animals versus 0.20±0.03 [P=0.002] at induction and 0.25±0.03 [P<0.001] at progression). Ex vivo positron emission tomographic imaging corroborated the (18)F-fluoromisonidazole uptake by the aorta of atherosclerotic rabbits. (18)F-fluorodeoxyglucose uptake also augmented in atherosclerotic animals, with an standardized uptake value mean of 0.43±0.02 at induction versus 0.35±0.02 in nonatherosclerotic animals (P=0.031) and no further increase at progression. By immunohistochemistry, hypoxia was mainly located in the macrophage-rich areas within the atheromatous core, whereas the macrophages close to the lumen were hypoxia-negative. Intraplaque neovessels were found predominantly in macrophage-rich hypoxic regions (pimonidazole(+)/hypoxia-inducible factor-1α(+)/RAM-11(+)). CONCLUSIONS Plaque hypoxia increases with disease progression and is present in macrophage-rich areas associated with neovascularization. (18)F-fluoromisonidazole positron emission tomographic imaging emerges as a new tool for the detection of atherosclerotic lesions.
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Affiliation(s)
- Jesus Mateo
- Department of Epidemiology, Atherothrombosis and Imaging, Centro Nacional de Investigaciones Cardiovasculares
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Abstract
Cerebral ischemia manifests widely in patient symptoms. Along with the clinical examination, imaging serves as a powerful tool throughout the course of ischemia-from acute onset to evolution. A thorough understanding of imaging modalities, their strengths and their limitations, is essential for capitalizing on the benefit of this complementary source of information for understanding the mechanism of disease, making therapeutic decisions, and monitoring patient response over time.
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Affiliation(s)
- May Nour
- Department of Neurology, David Geffen School of Medicine, UCLA Stroke Center, University of California, RNRC, RM 4-126, Los Angeles, CA 90095, USA; Department of Radiology, Division of Interventional Neuroradiology, University of California, Los Angeles, 757 Westwood plaza Suite 2129, Los Angeles, CA 90095, USA
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Alawneh JA, Moustafa RR, Marrapu ST, Jensen-Kondering U, Morris RS, Jones PS, Aigbirhio FI, Fryer TD, Carpenter TA, Warburton EA, Baron JC. Diffusion and perfusion correlates of the 18F-MISO PET lesion in acute stroke: pilot study. Eur J Nucl Med Mol Imaging 2013; 41:736-44. [PMID: 24126468 DOI: 10.1007/s00259-013-2581-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Accepted: 09/12/2013] [Indexed: 12/22/2022]
Abstract
PURPOSE Mapping the ischaemic penumbra in acute stroke is of considerable clinical interest. For this purpose, mapping tissue hypoxia with (18)F-misonidazole (FMISO) PET is attractive, and is straightforward compared to (15)O PET. Given the current emphasis on penumbra imaging using diffusion/perfusion MR or CT perfusion, investigating the relationships between FMISO uptake and abnormalities with these modalities is important. METHODS According to a prospective design, three patients (age 54-81 years; admission NIH stroke scale scores 16-22) with an anterior circulation stroke and extensive penumbra on CT- or MR-based perfusion imaging successfully completed FMISO PET, diffusion-weighted imaging and MR angiography 6-26 h after stroke onset, and follow-up FLAIR to map the final infarction. All had persistent proximal occlusion and a poor outcome despite thrombolysis. Significant FMISO trapping was defined voxel-wise relative to ten age-matched controls and mapped onto coregistered maps of the penumbra and irreversibly damaged ischaemic core. RESULTS FMISO trapping was present in all patients (volume range 18-119 ml) and overlapped mainly with the penumbra but also with the core in each patient. There was a significant (p ≤ 0.001) correlation in the expected direction between FMISO uptake and perfusion, with a sharp FMISO uptake bend around the expected penumbra threshold. CONCLUSION FMISO uptake had the expected overlap with the penumbra and relationship with local perfusion. However, consistent with recent animal data, our study suggests FMISO trapping may not be specific to the penumbra. If confirmed in larger samples, this preliminary finding would have potential implications for the clinical application of FMISO PET in acute ischaemic stroke.
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Affiliation(s)
- Josef A Alawneh
- Stroke Research Group, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
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A comparison of four PET tracers for brain hypoxia mapping in a rodent model of stroke. Nucl Med Biol 2013; 40:338-44. [PMID: 23294900 DOI: 10.1016/j.nucmedbio.2012.11.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Revised: 10/31/2012] [Accepted: 11/23/2012] [Indexed: 11/20/2022]
Abstract
INTRODUCTION Severe brain hypoxia in the territory of the occluded artery is a key feature of ischemic stroke. This region can be imaged using positron emission tomography (PET) and the standard hypoxia radiotracer (18)F-fluoromisonidazole ((18)F-FMISO). However, the utility of (18)F-FMISO is limited by its slow accumulation in the lesion. Therefore, this study investigated three hypoxia-sensitive radiotracers, namely the nitroimidazole (18)F-fluoroazomycin arabinoside ((18)F-FAZA) and two (64)Cu bis(thiosemicarbazone) complexes ((64)Cu-ATSM and (64)Cu-ATSE), expected to have improved pharmacokinetic profiles relative to (18)F-FMISO, in a rodent model of ischemic stroke. METHODS In anaesthetised Wistar rats, the distal middle cerebral artery was permanently occluded by electrocoagulation, the radiotracers administered intravenously and animals PET scanned for up to 3hours, followed by T2-weighted magnetic resonance imaging to map the infarct. RESULTS As expected, late and prominent (18)F-FMISO retention was observed despite lower tracer delivery into the affected region. Time-activity curves revealed that both (64)Cu-ATSM and (64)Cu-ATSE showed rapid entry and efflux from the brain, but did not show significant accumulation in the lesion. (18)F-FAZA showed limited brain penetration, and accumulation in the lesion was inconsistent, low and as slow as (18)F-FMISO. CONCLUSIONS This study suggests further development of these radiotracers as hypoxia markers for ischemic stroke may not be warranted.
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Skelding KA, Spratt NJ, Fluechter L, Dickson PW, Rostas JAP. αCaMKII is differentially regulated in brain regions that exhibit differing sensitivities to ischemia and excitotoxicity. J Cereb Blood Flow Metab 2012; 32:2181-92. [PMID: 22929440 PMCID: PMC3519412 DOI: 10.1038/jcbfm.2012.124] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Different brain regions exhibit differing sensitivities to ischemia/excitotoxicity. Whether these differences are due to perfusion or intrinsic factors has not been established. Herein, we found no apparent association between sensitivity to ischemia/excitotoxicity and the level of expression or basal phosphorylation of calcium/calmodulin-stimulated protein kinase II (αCaMKII) or glutamate receptors. However, we demonstrated significant differences in CaMKII-mediated responses after ischemia/excitotoxic stimulation in striatum and cortex. In vivo ischemia and in vitro excitotoxic stimulation produced more rapid phosphorylation of Thr253-αCaMKII in striatum compared with cortex, but equal rates of Thr286-αCaMKII phosphorylation. Phosphorylation by CaMKII of Ser831-GluA1 and Ser1303-GluN2B occurred more rapidly in striatum than in cortex after either stimulus. The differences between brain regions in CaMKII activation and its effects were not accounted for by differences in the expression of αCaMKII, glutamate receptors, or density of synapses. These results implicate intrinsic tissue differences in Thr253-αCaMKII phosphorylation in the differential sensitivities of brain regions to ischemia/excitotoxicity.
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Affiliation(s)
- Kathryn A Skelding
- School of Biomedical Sciences and Pharmacy, and The Hunter Medical Research Institute, Faculty of Health, The University of Newcastle, Callaghan, New South Wales, Australia
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Metabolic Imaging in Translational Stroke Research. Transl Stroke Res 2012. [DOI: 10.1007/978-1-4419-9530-8_41] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Abstract
Original experimental studies in nonhuman primate models of focal ischemia showed flow-related changes in evoked potentials that suggested a circumferential zone of low regional cerebral blood flow with normal K(+) homeostasis, around a core of permanent injury in the striatum or the cortex. This became the basis for the definition of the ischemic penumbra. Imaging techniques of the time suggested a homogeneous core of injury, while positing a surrounding 'penumbral' region that could be salvaged. However, both molecular studies and observations of vascular integrity indicate a more complex and dynamic situation in the ischemic core that also changes with time. The microvascular, cellular, and molecular events in the acute setting are compatible with heterogeneity of the injury within the injury center, which at early time points can be described as multiple 'mini-cores' associated with multiple 'mini-penumbras'. These observations suggest the progression of injury from many small foci to a homogeneous defect over time after the onset of ischemia. Recent observations with updated imaging techniques and data processing support these dynamic changes within the core and the penumbra in humans following focal ischemia.
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Affiliation(s)
- Gregory J del Zoppo
- Department of Medicine (Division of Hematology), University of Washington School of Medicine, Seattle, Washington 98104, USA.
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Single-subject statistical mapping of acute brain hypoxia in the rat following middle cerebral artery occlusion: A microPET study. Exp Neurol 2011; 229:251-8. [DOI: 10.1016/j.expneurol.2011.02.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2010] [Revised: 02/07/2011] [Accepted: 02/09/2011] [Indexed: 11/23/2022]
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Brekenfeld C, Schroth G, Mordasini P, Fischer U, Mono ML, Weck A, Arnold M, El-Koussy M, Gralla J. Impact of retrievable stents on acute ischemic stroke treatment. AJNR Am J Neuroradiol 2011; 32:1269-73. [PMID: 21566010 DOI: 10.3174/ajnr.a2494] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Retrievable stents combine the high recanalization rate of stents and the capability of removing the thrombus offered by mechanical thrombectomy devices. We hypothesized that retrievable stents shorten time to recanalization in the multimodal approach for endovascular stroke treatment. MATERIALS AND METHODS Forty consecutive patients with acute ischemic stroke and undergoing endovascular therapy were included. Treatment included thromboaspiration, thrombus disruption, thrombolysis, PTA, and stent placement. In 17 patients, a retrievable stent was used (group A) in addition to multimodal therapy. The remaining 23 patients constituted group B. Baseline characteristics, occlusion sites, urokinase dose, recanalization rate, and time to recanalization were compared between the groups. RESULTS Median NIHSS scores were higher in group A compared with group B on admission (19 versus 12.5; P = .018) but were not significantly different at day 1 (14 versus 10; P = .6). Intra-arterial thrombolysis was used in significantly fewer patients of group A than group B (53% versus 87%, respectively; P = .017), and median urokinase dose was lower in group A than in group B (250,000 IU versus 700,000 IU; P = .006). Time to recanalization was significantly shorter in group A compared with group B (median time to recanalization 52.5 minutes versus 90 minutes, respectively; P = .001). Recanalization rate was higher in group A than group B (94% versus 78%; P = .17). CONCLUSIONS Addition of retrievable stents to the multimodal endovascular approach for acute ischemic stroke treatment significantly reduces time to recanalization and further increases the recanalization rate.
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Affiliation(s)
- C Brekenfeld
- University Institute of Diagnostic and Interventional Neuroradiology, Inselspital, Bern, Switzerland.
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Spratt NJ, Donnan GA, McLeod DD, Howells DW. 'Salvaged' stroke ischaemic penumbra shows significant injury: studies with the hypoxia tracer FMISO. J Cereb Blood Flow Metab 2011; 31:934-43. [PMID: 20877386 PMCID: PMC3063627 DOI: 10.1038/jcbfm.2010.174] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The degree of cellular injury within the stroke ischaemic penumbra is controversial. Clinical and experimental studies using the hypoxia tracer fluoromisonidazole (FMISO) have shown retention of this tracer in the penumbra, but cellular outcome has not been well characterised. We hypothesised that macroscopically intact FMISO-retaining penumbral tissues would show evidence of microscopic injury, and that no FMISO retention would be seen in the infarct core. To determine the distribution of FMISO retention, a tritium-labelled tracer (hydrogen-3 FMISO ([(3)H]FMISO)) was administered 5 minutes after induction of 2-hour temporary middle cerebral artery occlusion. Coregistered brain histology and autoradiography at 24 hours revealed marked retention of FMISO within the infarct. However, 48% of the FMISO-retaining tissue was not infarcted. Within this noninfarcted tissue, only 27% (17 of 64) of sampled regions showed no evidence of neuronal loss, whereas 44% (28 of 64) showed injury to >50% of neurons within the sample. To determine whether FMISO retention occurred after the tissue was already committed to infarction, FMISO was administered 4 to 6 hours after the onset of permanent vessel occlusion. Intense FMISO retention was consistently seen throughout the infarct core. In conclusion, FMISO retention occurs both within the ischaemic penumbra and within the early infarct core. Most penumbral tissues show evidence of selective cellular injury.
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Affiliation(s)
- Neil J Spratt
- Hunter Medical Research Institute and University of Newcastle School of Biomedical Sciences and Pharmacy, Callaghan, New South Wales, Australia.
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Isozaki M, Kiyono Y, Arai Y, Kudo T, Mori T, Maruyama R, Kikuta KI, Okazawa H. Feasibility of 62Cu-ATSM PET for evaluation of brain ischaemia and misery perfusion in patients with cerebrovascular disease. Eur J Nucl Med Mol Imaging 2011; 38:1075-82. [DOI: 10.1007/s00259-011-1734-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Accepted: 01/04/2011] [Indexed: 11/29/2022]
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Abstract
The 'penumbra' is a concept coined in animal experiments suggesting that functionally impaired tissue can survive and recover if sufficient reperfusion is re-established within a limited time period, which depends on the level of residual flow. In an ischaemic territory, irreversible damage progresses over time from the centre of the most severe flow reduction to the periphery with less disturbed perfusion. This centrifugal progression of irreversible tissue damage is characterised by a complex cascade of interconnected electrophysiological, molecular, metabolic and perfusion disturbances. Waves of depolarisations, the peri infarct spreading depressions, inducing activation of ion pumps and liberation of excitatory transmitters play an important role in the drastically increased metabolic demand during reduced oxygen supply causing hypoxic tissue changes and lactacidosis, which further damage the tissue. Positron emission tomography allows the quantification of regional cerebral blood flow, the regional metabolic rate for oxygen and the regional oxygen extraction fraction, which can be used to identify regions with a critical reduction in these physiologic variables as indicators of penumbra and irreversible damage within ischaemic territories in animal models and patients with stroke. These positron emission tomography methods require arterial blood sampling and due to the complex logistics involved, are limited for routine application. Therefore, newer tracers were developed for the noninvasive detection of irreversible tissue damage (flumazenil) and of hypoxic tissue changes (fluoromisonidazole). As a widely applicable clinical tool, diffusion/perfusion-weighted magnetic resonance imaging is used; the 'mismatch' between perfusion and diffusion changes serves as a surrogate marker of the penumbra. However, in comparative studies of magnetic resonance imaging and positron emission tomography, diffusion-weighted imaging showed a high false-positive rate of irreversible damage, and the perfusion-weighted-diffusion-weighted mismatch overestimated the penumbra as defined by positron emission tomography. Advanced analytical procedures of magnetic resonance imaging data may improve the reliability of these surrogate markers but should be validated with quantitative procedures.
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Nuclear neuroimaging in acute and subacute ischemic stroke. Ann Nucl Med 2010; 24:629-38. [DOI: 10.1007/s12149-010-0421-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2010] [Accepted: 08/12/2010] [Indexed: 10/18/2022]
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Rojas S, Herance JR, Abad S, Jiménez X, Pareto D, Ruiz A, Torrent È, Figueiras FP, Popota F, Fernández-Soriano FJ, Planas AM, Gispert JD. Evaluation of Hypoxic Tissue Dynamics with 18F-FMISO PET in a Rat Model of Permanent Cerebral Ischemia. Mol Imaging Biol 2010; 13:558-564. [DOI: 10.1007/s11307-010-0371-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Sarrafzadeh AS, Nagel A, Czabanka M, Denecke T, Vajkoczy P, Plotkin M. Imaging of hypoxic-ischemic penumbra with (18)F-fluoromisonidazole PET/CT and measurement of related cerebral metabolism in aneurysmal subarachnoid hemorrhage. J Cereb Blood Flow Metab 2010; 30:36-45. [PMID: 19773799 PMCID: PMC2949093 DOI: 10.1038/jcbfm.2009.199] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
This study aimed to characterize hypoxic, but salvageable, tissue imaged by (18)F-fluoromisonidazole ((18)F-FMISO), combining with perfusion-computed tomography (PCT) for regional cerebral blood flow (rCBF) measurement and metabolism by microdialysis (MD) in aneurysmal subarachnoidal hemorrhage (SAH) patients. (18)F-FMISO positron-emission tomography (PET)/CT was performed within the period of possible vasospasm (day 6.8+/-3 after SAH) in seven SAH patients. In parallel, rCBF was determined within the MD region of interest (MD-ROI) (n=5). The MD catheter was inserted into the brain parenchyma with highest risk for ischemia; extracellular levels of glutamate and energy metabolites were registered at time of PET and hourly for 10 days. Twelve-month outcome was evaluated. In asymptomatic patients (n=3) no hypoxia was detected and glutamate levels were low (<10 mmol/L), whereas symptomatic patients had higher glutamate concentrations (P<0.001). Increased (18)F-FMISO uptake within the MD-ROI (n=3) was related to higher glutamate levels, while rCBF was above the ischemic range. Hypoxia (increased (18)F-FMISO uptake) was present in symptomatic patients and associated with relevant metabolic derangement of extracellular glutamate levels, whereas energy metabolism and rCBF were preserved. This technique has the potential to improve our understanding of the role of cellular hypoxia in aneurysmal SAH.
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Affiliation(s)
- Asita S Sarrafzadeh
- Department of Neurosurgery, Charité-Universitätsmedizin Berlin, Berlin, Germany.
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Abstract
Investigation of the interplay between the cerebral circulation and brain cellular function is fundamental to understanding both the pathophysiology and treatment of stroke. Currently, PET is the only technique that provides accurate, quantitative in vivo regional measurements of both cerebral circulation and cellular metabolism in human subjects. We review normal human cerebral blood flow and metabolism and human PET studies of ischemic stroke, carotid artery disease, vascular dementia, intracerebral hemorrhage and aneurysmal subarachnoid hemorrhage and discuss how these studies have added to our understanding of the pathophysiology of human cerebrovascular disease.
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Affiliation(s)
- William J. Powers
- Department of Neurology, University of North Carolina School of Medicine, Chapel Hill, NC
| | - Allyson R. Zazulia
- Departments of Neurology and Radiology, Washington University School of Medicine, St. Louis, MO
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Mountz JM. Imaging Pathophysiology and Neuroplasticity After Stroke. PET Clin 2010; 5:107-25. [DOI: 10.1016/j.cpet.2009.12.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Ma H, Zavala JA, Teoh H, Churilov L, Gunawan M, Ly J, Wright P, Phan T, Arakawa S, Davis SM, Donnan GA. Fragmentation of the classical magnetic resonance mismatch "penumbral" pattern with time. Stroke 2009; 40:3752-7. [PMID: 19850896 DOI: 10.1161/strokeaha.109.555011] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE The classical mismatch pattern in the middle cerebral artery territory stroke on MR is defined by a central diffusion-weighted image core with surrounding mismatch tissue. Because of variable rates of tissue salvage, we hypothesized that this pattern may fragment over time and may be influenced by vessel patency, mismatch volume, and infarct core location. METHODS Patients were recruited with MR studies performed within 48 hours of ischemic stroke. Mismatch patterns based on diffusion-weighted/perfusion-weighted images were categorized as classical (majority of the diffusion-weighted image within the perfusion-weighted image lesion) or nonclassical (fragmented) patterns. The proportion of patterns was assessed with reference to time, vessel patency, mismatch volume, and infarct core location. RESULTS Sixty-seven patients (33 classical [49.3%] and 34 nonclassical patterns [50.7%]) were studied within 48 hours (median age, 74.0 years). Compared to the nonclassical pattern, the classical pattern had a shorter time to MR (3.4 hours vs 10.4 hours; P=0.004) and a larger mismatch volume (62.0 mL vs 3.5 mL; P<0.0001). The positive predictors for the classical pattern were earlier time, vessel occlusion, superficial core location, and larger mismatch volume. CONCLUSIONS The classical mismatch pattern may fragment with time. Over 48 hours the classical pattern is seen earlier after stroke onset, with higher rates of vessel occlusion and larger mismatch volumes.
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Affiliation(s)
- Henry Ma
- National Stroke Research Institute, Austin Health, University of Melbourne, 300 Waterdale Rd, Heidelberg West, Vic 3081, Australia
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Cai W, Guzman R, Hsu AR, Wang H, Chen K, Sun G, Gera A, Choi R, Bliss T, He L, Li ZB, Maag ALD, Hori N, Zhao H, Moseley M, Steinberg GK, Chen X. Positron Emission Tomography Imaging of Poststroke Angiogenesis. Stroke 2009; 40:270-7. [DOI: 10.1161/strokeaha.108.517474] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background and Purpose—
Vascular endothelial growth factor (VEGF) and VEGF receptors (VEGFRs) play important roles during neurovascular repair after stroke. In this study, we imaged VEGFR expression with positron emission tomography (PET) to noninvasively analyze poststroke angiogenesis.
Methods—
Female Sprague-Dawley rats after distal middle cerebral artery occlusion surgery were subjected to weekly MRI,
18
F-FDG PET, and
64
Cu-DOTA-VEGF
121
PET scans. Several control experiments were performed to confirm the VEGFR specificity of
64
Cu-DOTA-VEGF
121
uptake in the stroke border zone. VEGFR, BrdU, lectin staining, and
125
I-VEGF
165
autoradiography on stroke brain tissue slices were performed to validate the in vivo findings.
Results—
T2-weighed MRI correlated with the “cold spot” on
18
F-FDG PET for rats undergoing distal middle cerebral artery occlusion surgery. The
64
Cu-DOTA-VEGF
121
uptake in the stroke border zone peaked at ≈10 days after surgery, indicating neovascularization as confirmed by histology (VEGFR-2, BrdU, and lectin staining). VEGFR specificity of
64
Cu-DOTA-VEGF
121
uptake was confirmed by significantly lower uptake of
64
Cu-DOTA-VEGF
mutant
in vivo and intense
125
I-VEGF
165
uptake ex vivo in the stroke border zone. No appreciable uptake of
64
Cu-DOTA-VEGF
121
was observed in the brain of sham-operated rats.
Conclusions—
For the first time to our knowledge, we successfully evaluated the VEGFR expression kinetics noninvasively in a rat stroke model. In vivo imaging of VEGFR expression could become a significant clinical tool to plan and monitor therapies aimed at improving poststroke angiogenesis.
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Affiliation(s)
- Weibo Cai
- From The Molecular Imaging Program at Stanford (W.C., A.R.H, H.W., L.H., K.C., Z-B.L., M.M., X.C.), Department of Radiology, Stanford University, Calif; Departments of Radiology and Medical Physics (W.C.), University of Wisconsin–Madison, Wis; Department of Neurosurgery (R.G., G.S., A.G., R.C., T.B., A-L.D.M., N.H., H.Z., G.K.S.), Stanford University, Calif
| | - Raphael Guzman
- From The Molecular Imaging Program at Stanford (W.C., A.R.H, H.W., L.H., K.C., Z-B.L., M.M., X.C.), Department of Radiology, Stanford University, Calif; Departments of Radiology and Medical Physics (W.C.), University of Wisconsin–Madison, Wis; Department of Neurosurgery (R.G., G.S., A.G., R.C., T.B., A-L.D.M., N.H., H.Z., G.K.S.), Stanford University, Calif
| | - Andrew R. Hsu
- From The Molecular Imaging Program at Stanford (W.C., A.R.H, H.W., L.H., K.C., Z-B.L., M.M., X.C.), Department of Radiology, Stanford University, Calif; Departments of Radiology and Medical Physics (W.C.), University of Wisconsin–Madison, Wis; Department of Neurosurgery (R.G., G.S., A.G., R.C., T.B., A-L.D.M., N.H., H.Z., G.K.S.), Stanford University, Calif
| | - Hui Wang
- From The Molecular Imaging Program at Stanford (W.C., A.R.H, H.W., L.H., K.C., Z-B.L., M.M., X.C.), Department of Radiology, Stanford University, Calif; Departments of Radiology and Medical Physics (W.C.), University of Wisconsin–Madison, Wis; Department of Neurosurgery (R.G., G.S., A.G., R.C., T.B., A-L.D.M., N.H., H.Z., G.K.S.), Stanford University, Calif
| | - Kai Chen
- From The Molecular Imaging Program at Stanford (W.C., A.R.H, H.W., L.H., K.C., Z-B.L., M.M., X.C.), Department of Radiology, Stanford University, Calif; Departments of Radiology and Medical Physics (W.C.), University of Wisconsin–Madison, Wis; Department of Neurosurgery (R.G., G.S., A.G., R.C., T.B., A-L.D.M., N.H., H.Z., G.K.S.), Stanford University, Calif
| | - Guohua Sun
- From The Molecular Imaging Program at Stanford (W.C., A.R.H, H.W., L.H., K.C., Z-B.L., M.M., X.C.), Department of Radiology, Stanford University, Calif; Departments of Radiology and Medical Physics (W.C.), University of Wisconsin–Madison, Wis; Department of Neurosurgery (R.G., G.S., A.G., R.C., T.B., A-L.D.M., N.H., H.Z., G.K.S.), Stanford University, Calif
| | - Atul Gera
- From The Molecular Imaging Program at Stanford (W.C., A.R.H, H.W., L.H., K.C., Z-B.L., M.M., X.C.), Department of Radiology, Stanford University, Calif; Departments of Radiology and Medical Physics (W.C.), University of Wisconsin–Madison, Wis; Department of Neurosurgery (R.G., G.S., A.G., R.C., T.B., A-L.D.M., N.H., H.Z., G.K.S.), Stanford University, Calif
| | - Raymond Choi
- From The Molecular Imaging Program at Stanford (W.C., A.R.H, H.W., L.H., K.C., Z-B.L., M.M., X.C.), Department of Radiology, Stanford University, Calif; Departments of Radiology and Medical Physics (W.C.), University of Wisconsin–Madison, Wis; Department of Neurosurgery (R.G., G.S., A.G., R.C., T.B., A-L.D.M., N.H., H.Z., G.K.S.), Stanford University, Calif
| | - Tonya Bliss
- From The Molecular Imaging Program at Stanford (W.C., A.R.H, H.W., L.H., K.C., Z-B.L., M.M., X.C.), Department of Radiology, Stanford University, Calif; Departments of Radiology and Medical Physics (W.C.), University of Wisconsin–Madison, Wis; Department of Neurosurgery (R.G., G.S., A.G., R.C., T.B., A-L.D.M., N.H., H.Z., G.K.S.), Stanford University, Calif
| | - Lina He
- From The Molecular Imaging Program at Stanford (W.C., A.R.H, H.W., L.H., K.C., Z-B.L., M.M., X.C.), Department of Radiology, Stanford University, Calif; Departments of Radiology and Medical Physics (W.C.), University of Wisconsin–Madison, Wis; Department of Neurosurgery (R.G., G.S., A.G., R.C., T.B., A-L.D.M., N.H., H.Z., G.K.S.), Stanford University, Calif
| | - Zi-Bo Li
- From The Molecular Imaging Program at Stanford (W.C., A.R.H, H.W., L.H., K.C., Z-B.L., M.M., X.C.), Department of Radiology, Stanford University, Calif; Departments of Radiology and Medical Physics (W.C.), University of Wisconsin–Madison, Wis; Department of Neurosurgery (R.G., G.S., A.G., R.C., T.B., A-L.D.M., N.H., H.Z., G.K.S.), Stanford University, Calif
| | - Anne-Lise D. Maag
- From The Molecular Imaging Program at Stanford (W.C., A.R.H, H.W., L.H., K.C., Z-B.L., M.M., X.C.), Department of Radiology, Stanford University, Calif; Departments of Radiology and Medical Physics (W.C.), University of Wisconsin–Madison, Wis; Department of Neurosurgery (R.G., G.S., A.G., R.C., T.B., A-L.D.M., N.H., H.Z., G.K.S.), Stanford University, Calif
| | - Nobutaka Hori
- From The Molecular Imaging Program at Stanford (W.C., A.R.H, H.W., L.H., K.C., Z-B.L., M.M., X.C.), Department of Radiology, Stanford University, Calif; Departments of Radiology and Medical Physics (W.C.), University of Wisconsin–Madison, Wis; Department of Neurosurgery (R.G., G.S., A.G., R.C., T.B., A-L.D.M., N.H., H.Z., G.K.S.), Stanford University, Calif
| | - Heng Zhao
- From The Molecular Imaging Program at Stanford (W.C., A.R.H, H.W., L.H., K.C., Z-B.L., M.M., X.C.), Department of Radiology, Stanford University, Calif; Departments of Radiology and Medical Physics (W.C.), University of Wisconsin–Madison, Wis; Department of Neurosurgery (R.G., G.S., A.G., R.C., T.B., A-L.D.M., N.H., H.Z., G.K.S.), Stanford University, Calif
| | - Michael Moseley
- From The Molecular Imaging Program at Stanford (W.C., A.R.H, H.W., L.H., K.C., Z-B.L., M.M., X.C.), Department of Radiology, Stanford University, Calif; Departments of Radiology and Medical Physics (W.C.), University of Wisconsin–Madison, Wis; Department of Neurosurgery (R.G., G.S., A.G., R.C., T.B., A-L.D.M., N.H., H.Z., G.K.S.), Stanford University, Calif
| | - Gary K. Steinberg
- From The Molecular Imaging Program at Stanford (W.C., A.R.H, H.W., L.H., K.C., Z-B.L., M.M., X.C.), Department of Radiology, Stanford University, Calif; Departments of Radiology and Medical Physics (W.C.), University of Wisconsin–Madison, Wis; Department of Neurosurgery (R.G., G.S., A.G., R.C., T.B., A-L.D.M., N.H., H.Z., G.K.S.), Stanford University, Calif
| | - Xiaoyuan Chen
- From The Molecular Imaging Program at Stanford (W.C., A.R.H, H.W., L.H., K.C., Z-B.L., M.M., X.C.), Department of Radiology, Stanford University, Calif; Departments of Radiology and Medical Physics (W.C.), University of Wisconsin–Madison, Wis; Department of Neurosurgery (R.G., G.S., A.G., R.C., T.B., A-L.D.M., N.H., H.Z., G.K.S.), Stanford University, Calif
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Ebinger M, De Silva DA, Christensen S, Parsons MW, Markus R, Donnan GA, Davis SM. Imaging the penumbra - strategies to detect tissue at risk after ischemic stroke. J Clin Neurosci 2008; 16:178-87. [PMID: 19097909 DOI: 10.1016/j.jocn.2008.04.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Revised: 03/05/2008] [Accepted: 04/06/2008] [Indexed: 10/21/2022]
Abstract
The aim of thrombolytic therapy after acute ischemic stroke is salvage of the ischemic penumbra. Several imaging techniques have been used to identify the penumbra in patients who may benefit from reperfusion beyond the currently narrow 3-hour time-window for thrombolysis. We discuss the advantages and disadvantages of positron emission tomography (PET), single photon emission computed tomography (SPECT), MRI and CT scans. We comment on concepts of clinical-imaging mismatch models and we explore the implications for clinical trials.
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Affiliation(s)
- M Ebinger
- Department of Neurology, Royal Melbourne Hospital, University of Melbourne, Parkville, Victoria 3050, Australia
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Abstract
Hypoxia, a condition of insufficient O2 to support metabolism, occurs when the vascular supply is interrupted, as in stroke or myocardial infarction, or when a tumor outgrows its vascular supply. When otherwise healthy tissues lose their O2 supply acutely, the cells usually die, whereas when cells gradually become hypoxic, they adapt by up-regulating the production of numerous proteins that promote their survival. These proteins slow the rate of growth, switch the mitochondria to glycolysis, stimulate growth of new vasculature, inhibit apoptosis, and promote metastatic spread. The consequence of these changes is that patients with hypoxic tumors invariably experience poor outcome to treatment. This has led the molecular imaging community to develop assays for hypoxia in patients, including regional measurements from O2 electrodes placed under CT guidance, several nuclear medicine approaches with imaging agents that accumulate with an inverse relationship to O2, MRI methods that measure either oxygenation directly or lactate production as a consequence of hypoxia, and optical methods with NIR and bioluminescence. The advantages and disadvantages of these approaches are reviewed, along with the individual strategies for validating different imaging methods. Ultimately the proof of value is in the clinical performance to predict outcome, select an appropriate cohort of patients to benefit from a hypoxia-directed treatment, or plan radiation fields that result in better local control. Hypoxia imaging in support of molecular medicine has become an important success story over the last decade and provides a model and some important lessons for development of new molecular imaging probes or techniques.
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Affiliation(s)
- Kenneth A Krohn
- Department of Radiology, University of Washington, Seattle, Washington 98195-6004, USA.
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Guadagno JV, Jones PS, Aigbirhio FI, Wang D, Fryer TD, Day DJ, Antoun N, Nimmo-Smith I, Warburton EA, Baron JC. Selective neuronal loss in rescued penumbra relates to initial hypoperfusion. Brain 2008; 131:2666-78. [PMID: 18678564 DOI: 10.1093/brain/awn175] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Selective neuronal loss (SNL) in the rescued penumbra could account for suboptimal clinical recovery despite effective early reperfusion. Previous studies of SNL used single-photon emission tomography (SPECT), did not account for potential volume loss secondary to collapse of the infarct cavity, and failed to show a relationship with initial hypoperfusion. Here, we obtained acute-stage computerized tomography (CT) perfusion and follow-up quantitative (11)C-flumazenil (FMZ)-PET to map SNL in the non-infarcted tissue and assess its relationship with acute-stage hypoperfusion. We prospectively recruited seven patients with evidence of (i) acute (<6 h) extensive middle cerebral artery territory ischaemia based on clinical deficit (National Institutes of Health stroke scale, NIHSS score range: 8-23) and CT Perfusion (CTp) findings and (ii) early recanalization (spontaneous or following thrombolysis) based on spectacular clinical recovery (DeltaNIHSS > or =6 at 24 h), good clinical outcome (NIHSS < or =5) and small final infarct (6/7 subcortical) on late-stage MRI. Ten age-matched controls were also studied. FMZ image analysis took into account potential post-stroke volume loss. Across patients, clusters of significantly reduced FMZ binding were more prevalent and extensive in the non-infarcted middle cerebral artery cortical areas than in the non-affected hemisphere (P = 0.028, Wilcoxon sign rank test). Voxel-based between-group comparisons revealed several large clusters of significantly reduced FMZ binding in the affected peri-insular, superior temporal and prefrontal cortices (FDR P < 0.05), as compared with no cluster on the unaffected side. Finally, comparing CTp and PET data revealed a significant negative correlation between FMZ binding and initial hypoperfusion. Applying correction for volume loss did not substantially alter the significance of these results. Although based on a small patient sample sometimes studied late after the index stroke, and as such preliminary, our results establish the presence and distribution of FMZ binding loss in ultimately non-infarcted brain areas after stroke. In addition, the data suggest that this binding loss is proportional to initial hypoperfusion, in keeping with the hypothesis that the rescued penumbra is affected by SNL. Although its clinical counterparts remain uncertain, it is tempting to speculate that peri-infarct SNL could represent a new therapeutic target.
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Affiliation(s)
- J V Guadagno
- Department of Clinical Neurosciences, Neurology Unit, Addenbrooke's Hospital, Cambridge, UK
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Takasawa M, Moustafa RR, Baron JC. Applications of nitroimidazole in vivo hypoxia imaging in ischemic stroke. Stroke 2008; 39:1629-37. [PMID: 18369176 DOI: 10.1161/strokeaha.107.485938] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE Nitroimidazole imaging is a promising contender for noninvasive in vivo mapping of brain hypoxia after stroke. However, there is a dearth of knowledge about the behavior of these compounds in the various pathophysiologic situations encountered in ischemic stroke. In this article we report the findings from a systematic review of the literature on the use of the nitroimidazoles to map hypoxia after stroke. SUMMARY OF REVIEW We describe the characteristics of nitroimidazoles as imaging tracers, their pharmacology, and results of both animal and clinical studies during and after focal cerebral ischemia. Findings in brain tumors are also presented to the extent that they enlighten results in stroke. Early results from application of kinetic modeling for quantitative measurement of tracer binding are briefly discussed. CONCLUSIONS Based on this literature review, nitroimidazole hypoxia imaging agents are of considerable interest in stroke because they appear, both in animal models and in humans, to specifically detect the severely hypoxic viable tissue, but not the reperfused nor the necrotic tissue. To fully realize this potential in stroke, however, formal validation by concurrent measurement of tissue oxygen tension, together with development of novel ligands with faster distribution kinetics, faster clearance from normal tissue, and well-defined trapping mechanisms, are important goals for future investigations.
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Affiliation(s)
- Masashi Takasawa
- University of Cambridge, Department of Clinical Neurosciences, Cambridge, UK
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50
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Stoeckel MC, Wittsack HJ, Meisel S, Seitz RJ. Pattern of cortex and white matter involvement in severe middle cerebral artery ischemia. J Neuroimaging 2007; 17:131-40. [PMID: 17441834 DOI: 10.1111/j.1552-6569.2007.00102.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND AND PURPOSE In middle cerebral artery (MCA) stroke, ischemia usually is unevenly distributed within the MCA territory. We sought to investigate which brain structures are critical for the acute neurological deficit in severe MCA stroke. METHODS We used magnetic resonance (MR) imaging and statistical parametric mapping in 64 consecutive stroke patients (64 +/-13 years) to study the pattern of the initial perfusion abnormality. RESULTS Patients with lesion progression had more severe time-to-peak (TTP) abnormalities (P < .0001) in the inferior frontal gyrus, superior temporal gyrus, insula, and underlying hemispheric white matter than those with lesion regression. Also, patients with lesion progression had more severe T2 abnormalities on day 8 than those with lesion regression. In contrast, the changes of water diffusion were similar among the two groups resulting in a perfusion-diffusion mismatch in lesion progression. TTP-lesions were related to the neurological deficit score (r(s)=-0.563, P < .0001), T2-lesions (r= 0.686, P < .0001), and cerebral artery abnormalities assessed on MR-angiography (r(s)= 0.399, P < .01). CONCLUSIONS In major MCA, stroke ischemia was most severe in the central portion of the MCA territory. It is suggested that involvement of hemispheric white matter accentuated the neurological deficit probably by affecting cortico-cortical and cortico-subcortical fibers.
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