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Hu JY, Kirilina E, Nierhaus T, Ovadia-Caro S, Livne M, Villringer K, Margulies D, Fiebach JB, Villringer A, Khalil AA. A novel approach for assessing hypoperfusion in stroke using spatial independent component analysis of resting-state fMRI. Hum Brain Mapp 2021; 42:5204-5216. [PMID: 34323339 PMCID: PMC8519861 DOI: 10.1002/hbm.25610] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 07/09/2021] [Accepted: 07/20/2021] [Indexed: 01/03/2023] Open
Abstract
Individualized treatment of acute stroke depends on the timely detection of ischemia and potentially salvageable tissue in the brain. Using functional MRI (fMRI), it is possible to characterize cerebral blood flow from blood‐oxygen‐level‐dependent (BOLD) signals without the administration of exogenous contrast agents. In this study, we applied spatial independent component analysis to resting‐state fMRI data of 37 stroke patients scanned within 24 hr of symptom onset, 17 of whom received follow‐up scans the next day. Our analysis revealed “Hypoperfusion spatially‐Independent Components” (HICs) whose spatial patterns of BOLD signal resembled regions of delayed perfusion depicted by dynamic susceptibility contrast MRI. These HICs were detected even in the presence of excessive patient motion, and disappeared following successful tissue reperfusion. The unique spatial and temporal features of HICs allowed them to be distinguished with high accuracy from other components in a user‐independent manner (area under the curve = 0.93, balanced accuracy = 0.90, sensitivity = 1.00, and specificity = 0.85). Our study therefore presents a new, noninvasive method for assessing blood flow in acute stroke that minimizes interpretative subjectivity and is robust to severe patient motion.
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Affiliation(s)
- Jiun-Yiing Hu
- Department of Internal Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Evgeniya Kirilina
- Department of Neurophysics, Max-Planck-Institute for Human Cognitive and Brain Sciences, Leipzig, Germany.,Neurocomputation and Neuroimaging Unit, Center for Cognitive Neuroscience Berlin (CCNB), Department of Education and Psychology, Freie Universität Berlin, Berlin, Germany
| | - Till Nierhaus
- Neurocomputation and Neuroimaging Unit, Center for Cognitive Neuroscience Berlin (CCNB), Department of Education and Psychology, Freie Universität Berlin, Berlin, Germany.,Department of Neurology, Max-Planck-Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | | | - Michelle Livne
- Center for Stroke Research Berlin, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Kersten Villringer
- Center for Stroke Research Berlin, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Daniel Margulies
- Centre National de la Recherche Scientifique (CNRS) UMR 7225, Frontlab, Institut du Cerveau et de la Moelle Épinière, Paris, France
| | - Jochen B Fiebach
- Center for Stroke Research Berlin, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Arno Villringer
- Department of Neurology, Max-Planck-Institute for Human Cognitive and Brain Sciences, Leipzig, Germany.,Berlin School of Mind and Brain, Humboldt Universität zu Berlin, Berlin, Germany
| | - Ahmed A Khalil
- Department of Neurology, Max-Planck-Institute for Human Cognitive and Brain Sciences, Leipzig, Germany.,Center for Stroke Research Berlin, Charité-Universitätsmedizin Berlin, Berlin, Germany.,Berlin School of Mind and Brain, Humboldt Universität zu Berlin, Berlin, Germany.,Berlin Institute of Health (BIH), Berlin, Germany
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2
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Tanrıtanır AC, Villringer K, Galinovic I, Grittner U, Kirilina E, Fiebach JB, Villringer A, Khalil AA. The Effect of Scan Length on the Assessment of BOLD Delay in Ischemic Stroke. Front Neurol 2020; 11:381. [PMID: 32431665 PMCID: PMC7214917 DOI: 10.3389/fneur.2020.00381] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 04/15/2020] [Indexed: 01/21/2023] Open
Abstract
Objectives: To evaluate the impact of resting-state functional MRI scan length on the diagnostic accuracy, image quality and lesion volume estimation of BOLD delay maps used for brain perfusion assessment in acute ischemic stroke. Methods: Sixty-three acute ischemic stroke patients received a 340 s resting-state functional MRI within 24 h of stroke symptom onset. BOLD delay maps were calculated from the full scan and four shortened versions (68 s, 136 s, 204 s, 272 s). The BOLD delay lesions on these maps were compared in terms of spatial overlap and volumetric agreement with the lesions derived from the full scans and with time-to-maximum (Tmax) lesions derived from DSC-MRI in a subset of patients (n = 10). In addition, the interpretability and quality of these maps were compared across different scan lengths using mixed models. Results: Shortened BOLD delay scans showed a small volumetric bias (ranging from 0.05 to 5.3 mL; between a 0.13% volumetric underestimation and a 7.7% overestimation relative to the mean of the volumes, depending on scan length) compared to the full scan. Decreased scan length was associated with decreased spatial overlap with both the BOLD delay lesions derived from the full scans and with Tmax lesions. Only the two shortest scan lengths (68 and 136 s) were associated with substantially decreased interpretability, decreased structure clarity, and increased noisiness of BOLD delay maps. Conclusions: BOLD delay maps derived from resting-state fMRI scans lasting 272 and 204 s provide sufficient diagnostic quality and adequate assessment of perfusion lesion volumes. Such shortened scans may be helpful in situations where quick clinical decisions need to be made.
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Affiliation(s)
| | - Kersten Villringer
- Center for Stroke Research, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Ivana Galinovic
- Center for Stroke Research, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Ulrike Grittner
- Institute of Biometry and Clinical Epidemiology, Charité - Universitätsmedizin Berlin, Berlin, Germany.,Berlin Institute of Health (BIH), Berlin, Germany
| | - Evgeniya Kirilina
- Department of Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany.,Center for Cognitive Neuroscience Berlin, Free University, Berlin, Germany
| | - Jochen B Fiebach
- Center for Stroke Research, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Arno Villringer
- Berlin School of Mind and Brain, Humboldt Universität zu Berlin, Berlin, Germany.,Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Ahmed A Khalil
- Center for Stroke Research, Charité - Universitätsmedizin Berlin, Berlin, Germany.,Berlin Institute of Health (BIH), Berlin, Germany.,Berlin School of Mind and Brain, Humboldt Universität zu Berlin, Berlin, Germany.,Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
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3
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Khalil AA, Villringer K, Filleböck V, Hu JY, Rocco A, Fiebach JB, Villringer A. Non-invasive monitoring of longitudinal changes in cerebral hemodynamics in acute ischemic stroke using BOLD signal delay. J Cereb Blood Flow Metab 2020; 40:23-34. [PMID: 30334657 PMCID: PMC6928563 DOI: 10.1177/0271678x18803951] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Relative delays in blood-oxygen-level-dependent (BOLD) signal oscillations can be used to assess cerebral perfusion without using contrast agents. However, little is currently known about the utility of this method in detecting clinically relevant perfusion changes over time. We investigated the relationship between longitudinal BOLD delay changes, vessel recanalization, and reperfusion in 15 acute stroke patients with vessel occlusion examined within 24 h of symptom onset (D0) and one day later (D1). We created BOLD delay maps using time shift analysis of resting-state functional MRI data and quantified perfusion lesion volume changes (using the D1/D0 volume ratio) and severity changes (using a linear mixed model) over time. Between baseline and follow-up, BOLD delay lesions shrank (median D1/D0 ratio = 0.2, IQR = 0.03-0.7) and BOLD delay severity decreased (b = -4.4 s) in patients with recanalization, whereas they grew (median D1/D0 ratio = 1.47, IQR = 1.1-1.7) and became more severe (b = 4.3 s) in patients with persistent vessel occlusion. Clinically relevant changes in cerebral perfusion in early stroke can be detected using BOLD delay, making this non-invasive method a promising option for detecting tissue at risk of infarction and monitoring stroke patients following recanalization therapy.
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Affiliation(s)
- Ahmed A Khalil
- Center for Stroke Research Berlin, Charité - Universitätsmedizin Berlin, Berlin, Germany.,Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany.,Mind, Brain, Body Institute, Berlin School of Mind and Brain, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Kersten Villringer
- Center for Stroke Research Berlin, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Vivien Filleböck
- Center for Stroke Research Berlin, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Jiun-Yiing Hu
- Center for Stroke Research Berlin, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Andrea Rocco
- Center for Stroke Research Berlin, Charité - Universitätsmedizin Berlin, Berlin, Germany.,Department of Neurology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Jochen B Fiebach
- Center for Stroke Research Berlin, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Arno Villringer
- Center for Stroke Research Berlin, Charité - Universitätsmedizin Berlin, Berlin, Germany.,Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany.,Mind, Brain, Body Institute, Berlin School of Mind and Brain, Humboldt-Universität zu Berlin, Berlin, Germany
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4
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Chen J, Sun D, Shi Y, Jin W, Wang Y, Xi Q, Ren C. Dynamic Alterations in Spontaneous Neural Activity in Multiple Brain Networks in Subacute Stroke Patients: A Resting-State fMRI Study. Front Neurosci 2019; 12:994. [PMID: 30666181 PMCID: PMC6330292 DOI: 10.3389/fnins.2018.00994] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Accepted: 12/11/2018] [Indexed: 01/09/2023] Open
Abstract
Objective: To examine whether subacute stroke patients would exhibit abnormal dynamic characteristics of brain activity relative to healthy controls (HC) and to investigate whether the altered dynamic regional indexes were associated with clinical behavior in stroke patients. Methods: The dynamic amplitude of low-frequency fluctuations (dALFF) and dynamic regional homogeneity (dReHo) in 42 subacute stroke patients and 55 healthy controls were compared. Correlation analyses between dALFF and dReHo in regions showing significant intergroup differences and clinical scores (i.e., the National Institutes of Health Stroke Scale, Fugl-Meyer assessment and lesion volume size) were conducted in stroke patients. Receiver operating characteristic (ROC) curve analysis was used to determine the potential value of altered dynamic regional indexes to identify stroke patients. Results: Significantly dALFF in the bilateral cerebellum posterior lobe (CPL), ipsilesional superior parietal lobe, ipsilesional inferior temporal gyrus (ITG), the midline supplementary motor area (SMA), ipsilesional putamen and lentiform nucleus were detected in stroke patients compared to HC. Relative to the HC group, the stroke patients showed significant differences in dReHo in the contralesional rectal gyrus, contralesional ITG, contralesional pons, ipsilesional middle frontal gyrus (MFG). Significant correlations between dALFF variability in midline SMA and Fugl-Meyer assessment (FMA) scores or between dReHo variability in the ipsilesional MFG and FMA scores were detected in stroke patients. Furthermore, the ROC curve revealed that dynamic ALFF at SMA and ReHo at ipsilesional MFG might have the potential to distinguish stroke patients. Conclusion: The pattern of intrinsic brain activity variability is altered in stroke patients compared with HC, and dynamic ALFF/ReHo might be potential tools to assess stroke patients' motor function.
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Affiliation(s)
- Jing Chen
- Department of Neurology, Shanghai Fifth People’s Hospital, Fudan University, Shanghai, China
| | - Dalong Sun
- Division of Gastroenterology, Department of Internal Medicine, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Yonghui Shi
- Department of Neurology, Shanghai Fifth People’s Hospital, Fudan University, Shanghai, China
| | - Wei Jin
- Department of Neurology, Shanghai Fifth People’s Hospital, Fudan University, Shanghai, China
| | - Yanbin Wang
- Department of Radiology, Shanghai East Hospital, Tongji University, Shanghai, China
| | - Qian Xi
- Department of Radiology, Shanghai East Hospital, Tongji University, Shanghai, China
| | - Chuancheng Ren
- Department of Neurology, Shanghai Fifth People’s Hospital, Fudan University, Shanghai, China
- Department of Neurology, Shanghai East Hospital, Tongji University, Shanghai, China
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5
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Min YS, Park JW, Jang KE, Lee HJ, Lee J, Lee YS, Jung TD, Chang Y. Power Spectral Density Analysis of Long-Term Motor Recovery in Patients With Subacute Stroke. Neurorehabil Neural Repair 2018; 33:38-46. [PMID: 30565493 DOI: 10.1177/1545968318818900] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
BACKGROUND Prognostic measures of long-term motor recovery are important in patients with stroke presenting with severe hemiplegia. OBJECTIVE We aimed to investigate whether initial power spectral density (PSD) analysis of resting-state functional magnetic resonance (fMRI) data can provide a sensitive prognostic predictor in patients with subacute stroke with severe hand disability. METHODS Twelve patients with good recovery, 14 patients with poor recovery, and 12 healthy subjects were included. PSD analysis was performed using resting-state fMRI data. Contralesional and ipsilesional PSD in the motor cortex were measured. Pearson correlation analysis was performed to assess a possible association between the difference in ipsilesional versus contralesional PSD and motor outcomes. A receiver operating characteristic (ROC) curve was constructed to estimate the discriminative value of the difference between the ipsilesional PSD and the contralesional PSD for good versus poor recovery. RESULTS There were no differences in PSD between the contralesional and ipsilesional hemispheres in the good recovery group ( P = .77). In contrast, there were significant differences in PSD between the 2 hemispheres in the poor recovery group ( P = .07). The difference in PSD between the 2 hemispheres had a positive correlation with post Brunnstrom stage scores. ROC analysis showed that the difference in PSD between the 2 hemispheres was sensitive in discriminating good versus poor recovery. CONCLUSION The present study suggests that PSD in the motor cortex may be a sensitive predictor of late-onset motor recovery following stroke.
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Affiliation(s)
- Yu-Sun Min
- 1 Kyungpook National University, Daegu, Korea.,2 Kyungpook National University Hospital, Daegu, Korea.,3 Seoul National University College of Medicine, Korea
| | - Jang Woo Park
- 4 Korea Institute of Radiological & Medical Sciences, Seoul, Korea
| | | | - Hui Joong Lee
- 1 Kyungpook National University, Daegu, Korea.,2 Kyungpook National University Hospital, Daegu, Korea
| | - Jongmin Lee
- 1 Kyungpook National University, Daegu, Korea.,2 Kyungpook National University Hospital, Daegu, Korea
| | - Yang-Soo Lee
- 1 Kyungpook National University, Daegu, Korea.,2 Kyungpook National University Hospital, Daegu, Korea
| | - Tae-Du Jung
- 1 Kyungpook National University, Daegu, Korea.,2 Kyungpook National University Hospital, Daegu, Korea
| | - Yongmin Chang
- 1 Kyungpook National University, Daegu, Korea.,2 Kyungpook National University Hospital, Daegu, Korea
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Dijkhuizen RM, Zaharchuk G, Otte WM. Assessment and modulation of resting-state neural networks after stroke. Curr Opin Neurol 2015; 27:637-43. [PMID: 25333606 DOI: 10.1097/wco.0000000000000150] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
PURPOSE OF REVIEW Stroke is a major cause of disability; however, most patients experience spontaneous partial recovery of functions in subacute to chronic phases. Poststroke loss and recovery of functions have been increasingly correlated with brain-wide alterations in the connectivity of neural networks, which is described in this review. Elucidation of the mechanisms of functional brain remodeling could reveal targets and strategies for more effective neurorehabilitation. RECENT FINDINGS Data from recent resting-state functional MRI, electroencephalography, magnetoencephalography, and optical imaging studies in patients and animal models have demonstrated that loss of function after stroke is closely associated with disrupted connectivity in large-scale networks beyond the lesion territory. Restoration of functional connectivity in the surviving networks appears to be critical for functional recovery, and this may be promoted with specific therapeutic strategies, such as robot-assisted training and noninvasive brain stimulation. The adaptability of functional networks relies on the structural integrity of neuronal pathways, but the relationship between the two remains incompletely understood. Furthermore, disturbed neurovascular coupling after stroke can confound hemodynamically based measurements of functional connectivity. SUMMARY Identification of key network processes in adaptive brain plasticity can aid in the prediction of functional outcome and the development of therapeutic interventions to support and promote recovery after stroke.
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Affiliation(s)
- Rick M Dijkhuizen
- aBiomedical MR Imaging and Spectroscopy Group, Image Sciences Institute, University Medical Center Utrecht, Utrecht, the Netherlands bDepartment of Radiology, Stanford University School of Medicine, Stanford, California, USA cDepartment of Pediatric Neurology, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, the Netherlands
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7
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Altered resting-state FMRI signals in acute stroke patients with ischemic penumbra. PLoS One 2014; 9:e105117. [PMID: 25121486 PMCID: PMC4133354 DOI: 10.1371/journal.pone.0105117] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2014] [Accepted: 07/20/2014] [Indexed: 11/19/2022] Open
Abstract
Background Identifying the ischemic penumbra in acute stroke subjects is important for the clinical decision making process. The aim of this study was to use resting-state functional magnetic resonance singal (fMRI) to investigate the change in the amplitude of low-frequency fluctuations (ALFF) of these subjects in three different subsections of acute stroke regions: the infarct core tissue, the penumbra tissue, and the normal brain tissue. Another aim of this study was to test the feasilbility of consistently detecting the penumbra region of the brain through ALFF analysis. Methods Sixteen subjects with first-ever acute ischemic stroke were scanned within 27 hours of the onset of stroke using magnetic resonance imaging. The core of infarct regions and penumbra regions were determined by diffusion and perfusion-weighted imaging respectively. The ALFF were measured from resting-state blood oxygen level dependent (BOLD) fMRI scans. The averaged relative ALFF value of each regions were correlated with the time after the onset of stroke. Results Relative ALFF values were significantly different in the infarct core tissue, penumbra tissue and normal brain tissue. The locations of lesions in the ALFF maps did not match perfectly with diffusion and perfusion-weighted imagings; however, these maps provide a contrast that can be used to differentiate between penumbra brain tissue and normal brain tissue. Significant correlations between time after stroke onset and the relative ALFF values were present in the penumbra tissue but not in the infarct core and normal brain tissue. Conclusion Preliminary results from this study suggest that the ALFF reflects the underlying neurovascular activity and has a great potential to estimate the brain tissue viability after ischemia. Results also show that the ALFF may contribute to acute stroke imaging for thrombolytic or neuroprotective therapies.
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Jahanian H, Ni WW, Christen T, Moseley ME, Tamura MK, Zaharchuk G. Spontaneous BOLD signal fluctuations in young healthy subjects and elderly patients with chronic kidney disease. PLoS One 2014; 9:e92539. [PMID: 24651703 PMCID: PMC3961376 DOI: 10.1371/journal.pone.0092539] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Accepted: 02/24/2014] [Indexed: 11/18/2022] Open
Abstract
Spontaneous fluctuations in blood oxygenation level-dependent (BOLD) images are the basis of resting-state fMRI and frequently used for functional connectivity studies. However, there may be intrinsic information in the amplitudes of these fluctuations. We investigated the possibility of using the amplitude of spontaneous BOLD signal fluctuations as a biomarker for cerebral vasomotor reactivity. We compared the coefficient of variation (CV) of the time series (defined as the temporal standard deviation of the time series divided by the mean signal intensity) in two populations: 1) Ten young healthy adults and 2) Ten hypertensive elderly subjects with chronic kidney disease (CKD). We found a statistically significant increase (P<0.01) in the CV values for the CKD patients compared with the young healthy adults in both gray matter (GM) and white matter (WM). The difference was independent of the exact segmentation method, became more significant after correcting for physiological signals using RETROICOR, and mainly arose from very low frequency components of the BOLD signal fluctuation (f<0.025 Hz). Furthermore, there was a strong relationship between WM and GM signal fluctuation CV's (R2 = 0.87) in individuals, with a ratio of about 1∶3. These results suggest that amplitude of the spontaneous BOLD signal fluctuations may be used to assess the cerebrovascular reactivity mechanisms and provide valuable information about variations with age and different disease states.
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Affiliation(s)
- Hesamoddin Jahanian
- Department of Radiology, Stanford University, Stanford, California, United States of America
- * E-mail:
| | - Wendy W. Ni
- Department of Radiology, Stanford University, Stanford, California, United States of America
- Department of Electrical Engineering, Stanford University, Stanford, California, Untied States of America
| | - Thomas Christen
- Department of Radiology, Stanford University, Stanford, California, United States of America
| | - Michael E. Moseley
- Department of Radiology, Stanford University, Stanford, California, United States of America
| | - Manjula Kurella Tamura
- Geriatric Research and Education Clinical Center, Palo Alto Veterans Affairs Health Care System and Division of Nephrology, Stanford University, Stanford, California, United States of America
| | - Greg Zaharchuk
- Department of Radiology, Stanford University, Stanford, California, United States of America
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Christen T, Jahanian H, Ni WW, Qiu D, Moseley ME, Zaharchuk G. Noncontrast mapping of arterial delay and functional connectivity using resting-state functional MRI: a study in Moyamoya patients. J Magn Reson Imaging 2014; 41:424-30. [PMID: 24419985 DOI: 10.1002/jmri.24558] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2013] [Accepted: 12/04/2013] [Indexed: 11/08/2022] Open
Abstract
PURPOSE To investigate if delays in resting-state spontaneous fluctuations of the BOLD (sfBOLD) signal can be used to create maps similar to time-to-maximum of the residue function (Tmax) in Moyamoya patients and to determine whether sfBOLD delays affect the results of brain connectivity mapping. MATERIALS AND METHODS Ten patients were scanned at 3 Tesla using a gradient-echo echo planar imaging sequence for sfBOLD imaging. Cross correlation analysis was performed between each brain voxel signal and a reference signal comprised of either the superior sagittal sinus (SSS) or whole brain (WB) average time course. sfBOLD delay maps were created based on the time shift necessary to maximize the correlation coefficient, and compared with dynamic susceptibility contrast Tmax maps. Standard and time-shifted resting-state BOLD connectivity analyses of the default mode network were compared. RESULTS Good linear correlations were found between sfBOLD delays and Tmax using the SSS as reference (r(2) = 0.8, slope = 1.4, intercept = -4.6) or WB (r(2) = 0.7, slope = 0.8, intercept = -3.2). New nodes of connectivity were found in delayed regions when accounting for delays in the analysis. CONCLUSION Resting-state sfBOLD imaging can create delay maps similar to Tmax maps without the use of contrast agents in Moyamoya patients. Accounting for these delays may affect the results of functional connectivity maps.
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Affiliation(s)
- Thomas Christen
- Department of Radiology, Stanford University, Stanford, California, USA
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10
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Abstract
Stroke is a serious healthcare problem with high mortality and long-term disability. However, to date, our ability to prevent and cure stroke remains limited. One important goal in stroke research is to identify the extent and location of lesion for treatment. In addition, accurately differentiating salvageable tissue from infarct and evaluating therapeutic efficacies are indispensible. These objectives could potentially be met with the assistance of modern neuroimaging techniques. This paper reviews current imaging methods commonly used in ischemic stroke research. These methods include positron emission tomography, computed tomography, T1 MRI, T2 MRI, diffusion and perfusion MRI, diffusion tensor imaging, blood-brain barrier permeability MRI, pH-weighted MRI, and functional MRI.
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Affiliation(s)
- Hsiao-Ying Wey
- University of Texas Health Science Center, San Antonio, Texas, USA
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11
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Wey HY, Duong TQ. Multimodal MRI of nonhuman primate stroke. Transl Stroke Res 2012; 3:84-9. [PMID: 24323756 DOI: 10.1007/s12975-012-0145-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Accepted: 01/19/2012] [Indexed: 01/18/2023]
Abstract
Stroke is the fourth leading cause of death. Despite decades of research, no neuroprotective drug has proven to be effective clinically. One widely accepted view to account for this negative outcome is that the rodent stroke model simply does not adequately reflect the complexity of human stroke. Recent failures of several high-profile neuroprotective drugs for stroke treatment in phase III clinical trials further underscore the importance of developing adequate animal models for stroke research. The brain organization and vascular circuitry of nonhuman primates (NHPs) are more homologous with humans than the widely used rodent for stroke modeling. The Stroke Therapy Academic Industry Roundtable, a national committee commissioned by the American Heart Association, recommended that clinically relevant NHP stroke models be established for developing and assessing neuroprotective drugs. The aim of this article is to review the challenges and applications of magnetic resonance imaging studies of NHP stroke models.
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Affiliation(s)
- Hsiao-Ying Wey
- Athinoula. A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachussetts General Hospital, Harvard Medical School, Building 120, 2nd Ave., Charlestown, Boston, MA, USA,
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Yao QL, Zhang HY, Nie BB, Fang F, Jiao Y, Teng GJ. MRI assessment of amplitude of low-frequency fluctuation in rat brains with acute cerebral ischemic stroke. Neurosci Lett 2012; 509:22-6. [DOI: 10.1016/j.neulet.2011.12.036] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Revised: 12/09/2011] [Accepted: 12/21/2011] [Indexed: 01/07/2023]
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13
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D'Arceuil HE, de Crespigny AJ. Imaging Stroke Evolution after Middle Cerebral Artery Occlusion in Non-human Primates. Open Neuroimag J 2011; 5:216-24. [PMID: 22253663 PMCID: PMC3256846 DOI: 10.2174/1874440001105010216] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Revised: 01/18/2011] [Accepted: 02/14/2011] [Indexed: 12/01/2022] Open
Abstract
This article reviews imaging approaches applied to the study of stroke in nonhuman primates. We briefly survey the various surgical and minimally invasive experimental stroke models in nonhuman primates, followed by a summary of studies using computed tomography, positron emission tomography and magnetic resonance imaging and spectroscopy to monitor stroke from the hyperacute phase (within minutes of the onset of cerebral ischemia) to the chronic phase (1 month and beyond).
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Affiliation(s)
- H E D'Arceuil
- Department of Radiology, Massachusetts General Hospital, Boston, MA, USA
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14
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Liu S, Fleysher R, Fleysher L, Joo CG, Ratai EM, González RG, Gonen O. Brain metabolites B1-corrected proton T1 mapping in the rhesus macaque at 3 T. Magn Reson Med 2010; 63:865-71. [PMID: 20373387 DOI: 10.1002/mrm.22270] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The accuracy of metabolic quantification in MR spectroscopy is limited by the unknown radiofrequency field and T(1). To address both issues in proton ((1)H) MR spectroscopy, we obtained radiofrequency field-corrected T(1) maps of N-acetylaspartate, choline, and creatine in five healthy rhesus macaques at 3 T. For efficient use of the 4 hour experiment, we used a new three-point protocol that optimizes the precision of T(1) in three-dimensional (1)H-MR spectroscopy localization for extensive, approximately 30%, brain coverage at 0.6 x 0.6 x 0.5 cm(3) = 180-microL spatial resolution. The resulting mean T(1)s in 700 voxels were N-acetylaspartate = 1232 +/- 44, creatine = 1238 +/- 23 and choline = 1107 +/- 56 ms (mean +/- standard error of the mean). Their histograms from all 140 voxels in each animal were similar in position and shape, characterized by standard errors of the mean of the full width at half maximum divided by their means of better than 8%. Regional gray matter N-acetylaspartate, choline, and creatine T(1)s (1333 +/- 43, 1265 +/- 52, and 1131 +/- 28 ms) were 5-10% longer than white matter: 1188 +/- 34, 1201 +/- 24, and 1082 +/- 50 ms (statistically significant for the N-acetylaspartate only), all within 10% of the corresponding published values in the human brain.
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Affiliation(s)
- Songtao Liu
- Department of Radiology, New York University School of Medicine, New York, New York, USA
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15
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Liu S, Gonen O, Fleysher R, Fleysher L, Babb JS, Soher BJ, Joo CG, Ratai EM, González RG. Metabolite proton T(2) mapping in the healthy rhesus macaque brain at 3 T. Magn Reson Med 2010; 62:1292-9. [PMID: 19780178 DOI: 10.1002/mrm.22117] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The structure and metabolism of the rhesus macaque brain, an advanced model for neurologic diseases and their treatment response, is often studied noninvasively with MRI and (1)H-MR spectroscopy. Due to the shorter transverse relaxation time (T(2)) at the higher magnetic fields these studies favor, the echo times used in (1)H-MR spectroscopy subject the metabolites to unknown T(2) weighting, decreasing the accuracy of quantification which is key for inter- and intra-animal comparisons. To establish the "baseline" (healthy animal) T(2) values, we mapped them for the three main metabolites' T(2)s at 3 T in four healthy rhesus macaques and tested the hypotheses that their mean values are similar (i) among animals; and (ii) to analogs regions in the human brain. This was done with three-dimensional multivoxel (1)H-MR spectroscopy at (0.6 x 0.6 x 0.5 cm)(3) = 180 microL spatial resolution over a 4.2 x 3.0 x 2.0 = 25 cm(3) ( approximately 30%) of the macaque brain in a two-point protocol that optimizes T(2) precision per unit time. The estimated T(2)s in several gray and white matter regions are all within 10% of those reported in the human brain (mean +/- standard error of the mean): N-acetylaspartate = 316 +/- 7, creatine = 177 +/- 3, and choline = 264 +/- 9 ms, with no statistically significant gray versus white matter differences.
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Affiliation(s)
- Songtao Liu
- Department of Radiology, New York University School of Medicine, New York, New York 10016, USA
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16
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Kiviniemi V, Remes J, Starck T, Nikkinen J, Haapea M, Silven O, Tervonen O. Mapping Transient Hyperventilation Induced Alterations with Estimates of the Multi-Scale Dynamics of BOLD Signal. Front Neuroinform 2009; 3:18. [PMID: 19636388 PMCID: PMC2715265 DOI: 10.3389/neuro.11.018.2009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2009] [Accepted: 06/22/2009] [Indexed: 11/24/2022] Open
Abstract
Temporal blood oxygen level dependent (BOLD) contrast signals in functional MRI during rest may be characterized by power spectral distribution (PSD) trends of the form 1/f(alpha). Trends with 1/f characteristics comprise fractal properties with repeating oscillation patterns in multiple time scales. Estimates of the fractal properties enable the quantification of phenomena that may otherwise be difficult to measure, such as transient, non-linear changes. In this study it was hypothesized that the fractal metrics of 1/f BOLD signal trends can map changes related to dynamic, multi-scale alterations in cerebral blood flow (CBF) after a transient hyperventilation challenge. Twenty-three normal adults were imaged in a resting-state before and after hyperventilation. Different variables (1/f trend constant alpha, fractal dimension D(f), and, Hurst exponent H) characterizing the trends were measured from BOLD signals. The results show that fractal metrics of the BOLD signal follow the fractional Gaussian noise model, even during the dynamic CBF change that follows hyperventilation. The most dominant effect on the fractal metrics was detected in grey matter, in line with previous hyperventilation vaso-reactivity studies. The alpha was able to differentiate also blood vessels from grey matter changes. D(f) was most sensitive to grey matter. H correlated with default mode network areas before hyperventilation but this pattern vanished after hyperventilation due to a global increase in H. In the future, resting-state fMRI combined with fractal metrics of the BOLD signal may be used for analyzing multi-scale alterations of cerebral blood flow.
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Affiliation(s)
- Vesa Kiviniemi
- Department of Diagnostic Radiology, Oulu University HospitalOulu, Finland
| | - Jukka Remes
- Department of Diagnostic Radiology, Oulu University HospitalOulu, Finland
- Department of Information and Electrical Engineering, University of OuluOulu, Finland
| | - Tuomo Starck
- Department of Diagnostic Radiology, Oulu University HospitalOulu, Finland
| | - Juha Nikkinen
- Department of Diagnostic Radiology, Oulu University HospitalOulu, Finland
| | - Marianne Haapea
- Department of Diagnostic Radiology, Oulu University HospitalOulu, Finland
| | - Olli Silven
- Department of Information and Electrical Engineering, University of OuluOulu, Finland
| | - Osmo Tervonen
- Department of Diagnostic Radiology, Oulu University HospitalOulu, Finland
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Spontaneous low-frequency blood oxygenation level-dependent fluctuations and functional connectivity analysis of the 'resting' brain. Magn Reson Imaging 2008; 26:1055-64. [PMID: 18657923 DOI: 10.1016/j.mri.2008.05.008] [Citation(s) in RCA: 154] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2008] [Accepted: 05/15/2008] [Indexed: 12/31/2022]
Abstract
Functional magnetic resonance imaging techniques using the blood oxygenation level-dependent (BOLD) contrast are widely used to map human brain function by relating local hemodynamic responses to neuronal stimuli compared to control conditions. There is increasing interest in spontaneous cerebral BOLD fluctuations that are prominent in the low-frequency range (<0.1 Hz) and show intriguing spatio-temporal correlations in functional networks. The nature of these signal fluctuations remains unclear, but there is accumulating evidence for a neural basis opening exciting new avenues to study human brain function and its connectivity at rest. Moreover, an increasing number of patient studies report disease-dependent variation in the amplitude and spatial coherence of low-frequency BOLD fluctuations (LFBF) that may afford greater diagnostic sensitivity and easier clinical applicability than standard fMRI. The main disadvantage of this emerging tool relates to physiological (respiratory, cardiac and vasomotion) and motion confounds that are challenging to disentangle requiring thorough preprocessing. Technical aspects of functional connectivity fMRI analysis and the neuroscientific potential of spontaneous LFBF in the default mode and other resting-state networks have been recently reviewed. This review will give an update on the current knowledge of the nature of LFBF, their relation to physiological confounds and potential for clinical diagnostic and pharmacological studies.
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