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Szöllősi D, Hegedűs N, Veres DS, Futó I, Horváth I, Kovács N, Martinecz B, Dénes Á, Seifert D, Bergmann R, Lebeda O, Varga Z, Kaleta Z, Szigeti K, Máthé D. Evaluation of Brain Nuclear Medicine Imaging Tracers in a Murine Model of Sepsis-Associated Encephalopathy. Mol Imaging Biol 2019; 20:952-962. [PMID: 29736562 PMCID: PMC6244542 DOI: 10.1007/s11307-018-1201-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Purpose The purpose of this study was to evaluate a set of widely used nuclear medicine imaging agents as possible methods to study the early effects of systemic inflammation on the living brain in a mouse model of sepsis-associated encephalopathy (SAE). The lipopolysaccharide (LPS)-induced murine systemic inflammation model was selected as a model of SAE. Procedures C57BL/6 mice were used. A multimodal imaging protocol was carried out on each animal 4 h following the intravenous administration of LPS using the following tracers: [99mTc][2,2-dimethyl-3-[(3E)-3-oxidoiminobutan-2-yl]azanidylpropyl]-[(3E)-3-hydroxyiminobutan-2-yl]azanide ([99mTc]HMPAO) and ethyl-7-[125I]iodo-5-methyl-6-oxo-4H-imidazo[1,5-a][1,4]benzodiazepine-3-carboxylate ([125I]iomazenil) to measure brain perfusion and neuronal damage, respectively; 2-deoxy-2-[18F]fluoro-d-glucose ([18F]FDG) to measure cerebral glucose uptake. We assessed microglia activity on another group of mice using 2-[6-chloro-2-(4-[125I]iodophenyl)-imidazo[1,2-a]pyridin-3-yl]-N-ethyl-N-methyl-acetamide ([125I]CLINME). Radiotracer uptakes were measured in different brain regions and correlated. Microglia activity was also assessed using immunohistochemistry. Brain glutathione levels were measured to investigate oxidative stress. Results Significantly reduced perfusion values and significantly enhanced [18F]FDG and [125I]CLINME uptake was measured in the LPS-treated group. Following perfusion compensation, enhanced [125I]iomazenil uptake was measured in the LPS-treated group’s hippocampus and cerebellum. In this group, both [18F]FDG and [125I]iomazenil uptake showed highly negative correlation to perfusion measured with ([99mTc]HMPAO uptake in all brain regions. No significant differences were detected in brain glutathione levels between the groups. The CD45 and P2Y12 double-labeling immunohistochemistry showed widespread microglia activation in the LPS-treated group. Conclusions Our results suggest that [125I]CLINME and [99mTc]HMPAO SPECT can be used to detect microglia activation and brain hypoperfusion, respectively, in the early phase (4 h post injection) of systemic inflammation. We suspect that the enhancement of [18F]FDG and [125I]iomazenil uptake in the LPS-treated group does not necessarily reflect neural hypermetabolism and the lack of neuronal damage. They are most likely caused by processes emerging during neuroinflammation, e.g., microglia activation and/or immune cell infiltration. Electronic supplementary material The online version of this article (10.1007/s11307-018-1201-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Dávid Szöllősi
- Department of Biophysics and Radiation Biology, Semmelweis Univ, Budapest, H-1094, Hungary
| | - Nikolett Hegedűs
- Department of Biophysics and Radiation Biology, Semmelweis Univ, Budapest, H-1094, Hungary
| | - Dániel S Veres
- Department of Biophysics and Radiation Biology, Semmelweis Univ, Budapest, H-1094, Hungary
| | - Ildikó Futó
- Department of Biophysics and Radiation Biology, Semmelweis Univ, Budapest, H-1094, Hungary
| | - Ildikó Horváth
- Department of Biophysics and Radiation Biology, Semmelweis Univ, Budapest, H-1094, Hungary
| | - Noémi Kovács
- CROmed Translational Research Centers, Budapest, H-1047, Hungary
| | - Bernadett Martinecz
- Laboratory of Neuroimmunology, Institute of Experimental Medicine, Budapest, Hungary
| | - Ádám Dénes
- Laboratory of Neuroimmunology, Institute of Experimental Medicine, Budapest, Hungary
| | - Daniel Seifert
- Nuclear Physics Institute of the CAS, CZ 250 68, Rez, Czech Republic
| | - Ralf Bergmann
- Helmholz-Zentrum Dresden-Rossendorf, Radiopharmazie Radiopharmaceutische Biologie, Dresden, Germany
| | - Ondřej Lebeda
- Nuclear Physics Institute of the CAS, CZ 250 68, Rez, Czech Republic
| | - Zoltán Varga
- Department of Biophysics and Radiation Biology, Semmelweis Univ, Budapest, H-1094, Hungary.,Biological Nanochemistry Research Group, Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
| | - Zoltán Kaleta
- Progressio Fine Chemical Engineering Ltd, Székesfehérvár, Hungary
| | - Krisztián Szigeti
- Department of Biophysics and Radiation Biology, Semmelweis Univ, Budapest, H-1094, Hungary.
| | - Domokos Máthé
- CROmed Translational Research Centers, Budapest, H-1047, Hungary
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Ejaz S, Williamson DJ, Ahmed T, Sitnikov S, Hong YT, Sawiak SJ, Fryer TD, Aigbirhio FI, Baron JC. Characterizing infarction and selective neuronal loss following temporary focal cerebral ischemia in the rat: a multi-modality imaging study. Neurobiol Dis 2012; 51:120-32. [PMID: 23146994 DOI: 10.1016/j.nbd.2012.11.002] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Revised: 10/05/2012] [Accepted: 11/01/2012] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND AND PURPOSE Current models dictate that, depending on occurrence of early reperfusion, the ischemic penumbra either undergoes or escapes infarction (i.e., "pan-necrosis"). However, tissue outcome following temporary middle-cerebral artery occlusion (tMCAo) in rodents can also include selective neuronal loss (SNL), which even if subtle may impede functional recovery. In order to explore the pathophysiology of ischemic stroke, determine potential therapeutic targets and monitor effects of therapy, in vivo imaging surrogates of these varied histopathological outcomes applicable in the clinical setting would be useful. Although hyperintense signal on T(2)-weighted MRI in the chronic post-stroke stage is considered a reliable surrogate of tissue infarction, SNL is not associated with T(2)W abnormal signal. In the clinical setting, the neuron-specific PET ligand (11)C-flumazenil (FMZ) has been used to identify both pan-necrosis and peri-infarct SNL, but this inference has not been histopathological confirmed so far. Here we investigated the late tissue sequelae of tMCAo in the rodent using in vivo T(2)W MRI and FMZ-PET against post mortem immunohistochemistry as gold standard. METHODS Adult spontaneously hypertensive rats (SHRs) underwent 45 min distal-clip middle-cerebral artery occlusion and, 28 days later, FMZ-PET and T(2)W-MRI, immediately followed by immunohistochemistry for neuronal loss (NeuN), activated microglia and astrocytosis. Based on standard histopathological definitions, ischemic lesions were classified into pan-necrosis, partial infarction or SNL. NeuN changes and FMZ binding across the whole hemisphere were quantified in the same set of 44 regions-of-interest according to previously validated protocols; linear regressions between these two measures were carried out both within and across subjects. RESULTS Both cortical pan-necrosis/partial infarction and SNL were present in all rats except one, where SNL was isolated and extensive. Infarction/partial infarction, but not SNL, was associated with T(2)W hyperintense signals and cortical atrophy. In contrast, FMZ binding was decreased in all types of lesions including SNL, in proportion with NeuN staining intensity both within (p<0.05 to <0.001) and across (p<0.001) subjects, including the subject that showed pure SNL (p=0.01). CONCLUSION This novel study revealed three main facts: i) long-term histopathological cortical changes following 45 min tMCAo in SHRs included all three of SNL, partial infarction and frank infarction; ii) T2W MRI showed conspicuous high signal lesions for complete or partial infarction, but no changes for SNL; and iii) FMZ-PET was sensitive to all three types of tMCAo-induced histopathological changes, including isolated SNL, suggesting it is a valid surrogate for the histological sequelae of focal cerebral ischemia. In addition, the finding of almost universal completed cortical infarction at 28 days differed from our previous findings at 14-day survival using the same model and rat strain, where SNL was the almost exclusive outcome, possibly representing delayed infarct maturation. Prospective studies are needed to investigate this interesting possibility.
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Affiliation(s)
- Sohail Ejaz
- Stroke Research Group, Department of Clinical Neurosciences, Addenbrooke's Hospital, University of Cambridge, Cambridge, UK
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Yamauchi H, Kudoh T, Kishibe Y, Iwasaki J, Kagawa S. Selective neuronal damage and chronic hemodynamic cerebral ischemia. Ann Neurol 2007; 61:454-65. [PMID: 17380523 DOI: 10.1002/ana.21104] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
OBJECTIVE In atherothrombotic internal carotid artery or middle cerebral artery (MCA) occlusive disease, chronic hemodynamic compromise may increase the risk for cerebral ischemic damage. To determine whether selective neuronal damage demonstrated as a decrease in central benzodiazepine receptor (BZR) in the normal-appearing cerebral cortex is associated with increased oxygen extraction fraction (OEF) (misery perfusion). METHODS We measured BZR and OEF using positron emission tomography in 105 nondisabled patients with atherothrombotic internal carotid artery or MCA occlusive disease and no cortical infarction. By using three-dimensional stereotactic surface projections and the stereotactic extraction estimation method, without correction for partial volume effects, the abnormally decreased BZR index [(the extent of the pixels with Z-score more than 2 compared with controls) x (average Z-score in those pixels)] in the cerebral cortex of the MCA distribution with arterial disease was calculated, and it was found to be correlated with the mean hemispheric value of OEF and several clinical variables. RESULTS All patients had pixels with abnormally decreased BZR, with the extent varying from 0.04 to 60.91%. Multivariate analysis showed that the abnormally decreased BZR index was positively correlated with the value of OEF and the history of stroke, whereas it was negatively correlated with the presence of hypercholesterolemia with statin treatment. Follow-up examinations of 17 patients without ischemic episode showed that a decrease of BZR was associated with an increase of OEF. INTERPRETATION In atherothrombotic internal carotid artery or MCA occlusive disease, misery perfusion may cause selective neuronal damage, and statins might have beneficial effects against neuronal damage.
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Abstract
Because it is the main determinant of clinical recovery, early reperfusion of the ischemic penumbra has become the mainstay of acute stroke therapy. Although early permanent recanalization can be associated with spectacular and complete recovery, some patients in fact exhibit delayed or incomplete recovery, even despite small infarcts on late structural imaging. This might result from tissue inflammation and selective neuronal death/damage, two probably inter-related cellular events well described in the animal literature, precluding full functional restoration in the salvaged penumbra. However, impact of these processes on recovery may be complex because of the interplay with ongoing plasticity and the possible promoting effect of inflammation on the latter. Preliminary results from imaging studies of inflammation and selective neuronal loss after middle cerebral artery territory stroke, using radioligands of the central benzodiazepine receptor and the activated microglia, respectively, reviewed here, suggest these phenomena also exist in man, although their relationship with acute-stage hypoperfusion and their impact on clinical recovery, if any, remain poorly understood. Furthermore, their inter-relationships in the salvaged penumbra have not been addressed. Better understanding of these potentially harmful processes might help to maximize benefits from thrombolysis, and could also have implications for patients who enjoy spontaneous recanalization.
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Affiliation(s)
- J-C Baron
- University of Cambridge, Department of Clinical Neurosciences, Neurology Unit, Addenbrookes Hospital, Cambridge, UK.
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Song HC, Bom HS, Cho KH, Kim BC, Seo JJ, Kim CG, Yang DJ, Kim EE. Prognostication of recovery in patients with acute ischemic stroke through the use of brain SPECT with Technetium-99m--labeled metronidazole. Stroke 2003; 34:982-6. [PMID: 12649518 DOI: 10.1161/01.str.0000062902.94892.f5] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE We hypothesized that technetium-99m-ethylene dicysteine-metronidazole (99mTc-EC-MN) localizes to brain tissue that is hypoxic but viable. This study prospectively evaluated the relationship between neurological outcome and uptake of 99mTc-EC-MN in peri-infarcted regions of the brain. METHODS Eight patients with acute ischemic stroke in the territory of the left middle cerebral artery underwent 99mTc-EC-MN and 99mTc-ethyl cysteinate dimer (ECD) brain SPECTs on the same day during the subacute stage (10.3+/-2.5 days). The infarct volumes from 99mTc-ECD images (IV(ECD)), infarct volumes from diffusion-weighted MRI images (IV(DW)), and hypoxic volume (HV) from 99mTc-EC-MN images were calculated. The net infarct volume (NIV(ECD)) was defined as IV(ECD) minus HV. The National Institutes of Health Stroke Scale scores were measured on admission and days 1, 3, 7, and 30. RESULTS IV(ECD) was greater than IV(DW). The lesion-to-normal count-density ratios of 99mTc-EC-MN ranged from 1.80 to 5.96. HV was 60.2+/-65.2 cm3, and the mean percent HV was 24.5+/-28.1% of IV(ECD). NIV(ECD) was 162.6+/-133.4 cm3 and was significantly smaller than IV(ECD). NIV(ECD) was significantly correlated with National Institutes of Health Stroke Scale score at 1 month and was a significant predictor of neurological deficit at 1 month. CONCLUSIONS 99mTc-EC-MN brain SPECT can detect hypoxic tissue after acute ischemic stroke and, in combination with 99mTc-ECD brain SPECT, is useful in predicting neurological outcome in ischemic stroke patients.
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Affiliation(s)
- Ho-Chun Song
- Department of Nuclear Medicine, Chonnam National University Hospital, 8 Hak-Dong, Dong-Gu, Gwangju, South Korea
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Müller V, Saur D, Klutmann S, Weiller C, Röther J, Clausen M. Experience with 123I-iomazenil SPECT in acute cerebral infarction. Nucl Med Commun 2002; 23:1191-6. [PMID: 12464784 DOI: 10.1097/00006231-200212000-00007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Neuronal cells are susceptible to cerebral ischaemia. As gamma-aminobutyric acid(A) (GABA(A)) receptors are specific for neurones, functional receptor imaging using I-iomazenil (IMZ), a ligand to the GABA benzodiazepine receptor, has been proposed as an imaging modality for the assessment of neuronal integrity. However, there is only limited experience with IMZ in patients with acute cerebral infarction. Therefore, the aim of this study was to evaluate IMZ single photon emission computed tomography (SPECT) in patients with acute cerebral ischaemia. IMZ SPECT was performed in 21 patients with acute cerebral infarction 7-10 days after stroke onset. Eleven patients underwent systemic thrombolysis within 6 h after symptom onset (group 1), whereas 10 patients were treated conservatively (group 2). IMZ (150-200 MBq) was injected intravenously and imaging was performed using a dedicated four-head SPECT camera at 5 min (perfusion) and 90 min (receptor distribution) post-injection, with an acquisition time of 50 min each. Images were analysed by visual inspection. Four patients showed normal IMZ distribution, and 17 patients showed abnormalities of IMZ uptake on both early and late images. In six patients with regional uptake deficits, a crossed cerebellar diaschisis was observed on early images. Cerebellar inhomogeneity of tracer uptake was absent at the time of late images in all six patients. In eight patients, areas of hypoperfusion corresponded exactly to the regions of receptor deficiency (match). In five patients, preserved neuronal integrity was present in hypoperfused areas (mismatch). In four patients, normally or even hyperperfused areas exhibited regional receptor deficiency (inverse mismatch). In conclusion, IMZ SPECT demonstrated differences between regional perfusion and receptor distribution in about one-half of patients 7-10 days after acute cerebral ischaemia. Interesting patterns between the early phase (perfusion) and the late phase (receptor distribution) were found. These patterns are indicative of the heterogeneous development of cerebral ischaemia where, even days after stroke onset, areas of hypoperfusion but preserved neuronal integrity may be present. However, the evaluation of the potential clinical and therapeutic impact of individual IMZ distribution patterns requires further investigation.
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Affiliation(s)
- V Müller
- Department of Nuclear Medicine, University Hospital Hamburg-Eppendorf, Hamburg, Germany.
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Tsuchida T, Yonekura Y, Sadato N, Takahashi N, Yamamoto K, Ishii Y. Prediction of improvement of cerebral perfusion with I-123 iomazenil SPECT. Ann Nucl Med 1999; 13:265-8. [PMID: 10510884 DOI: 10.1007/bf03164903] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
We report a case of 61-year old man who was suffering from cerebrovascular disease with right hemiparesis and received I-123 iomazenil (IMZ) SPECT prior to carotid endoarterectomy. Severe stenosis of the right internal carotid artery and occlusion of the left middle cerebral artery (MCA) were revealed by cerebral angiography, and a hypoperfused area in left MCA territory and crossed cerebellar diaschisis (CCD) on I-123 IMP SPECT was demonstrated. In contrast, IMZ SPECT showed symmetric normal distribution. After the carotid endoarterectomy, the hypoperfused area in left MCA territory on IMP SPECT and hemiparesis had improved. It is thought that IMZ SPECT can be a useful tool for the prediction of improvement of cerebral perfusion and the clinical outcome.
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Affiliation(s)
- T Tsuchida
- Department of Radiology, Fukui Medical University, Japan
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