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Korponay C, Janes AC, Frederick BB. Brain-wide functional connectivity artifactually inflates throughout functional magnetic resonance imaging scans. Nat Hum Behav 2024; 8:1568-1580. [PMID: 38898230 DOI: 10.1038/s41562-024-01908-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Accepted: 05/03/2024] [Indexed: 06/21/2024]
Abstract
Functional magnetic resonance imaging (fMRI) is a central tool for investigating human brain function, organization and disease. Here, we show that fMRI-based estimates of functional brain connectivity artifactually inflate at spatially heterogeneous rates during resting-state and task-based scans. This produces false positive connection strength changes and spatial distortion of brain connectivity maps. We demonstrate that this artefact is driven by temporal inflation of the non-neuronal, systemic low-frequency oscillation (sLFO) blood flow signal during fMRI scanning and is not addressed by standard denoising procedures. We provide evidence that sLFO inflation reflects perturbations in cerebral blood flow by respiration and heart rate changes that accompany diminishing arousal during scanning, although the mechanisms of this pathway are uncertain. Finally, we show that adding a specialized sLFO denoising procedure to fMRI processing pipelines mitigates the artifactual inflation of functional connectivity, enhancing the validity and within-scan reliability of fMRI findings.
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Affiliation(s)
- Cole Korponay
- Department of Psychiatry, Harvard University Medical School, Boston, MA, USA.
- McLean Hospital Brain Imaging Center, Belmont, MA, USA.
| | - Amy C Janes
- Neuroimaging Research Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Bethesda, MD, USA
| | - Blaise B Frederick
- Department of Psychiatry, Harvard University Medical School, Boston, MA, USA
- McLean Hospital Brain Imaging Center, Belmont, MA, USA
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2
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Schneider SC, Kaczmarz S, Göttler J, Kufer J, Zott B, Priller J, Kallmayer M, Zimmer C, Sorg C, Preibisch C. Stronger influence of systemic than local hemodynamic-vascular factors on resting-state BOLD functional connectivity. Neuroimage 2023; 281:120380. [PMID: 37741595 DOI: 10.1016/j.neuroimage.2023.120380] [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: 04/06/2023] [Revised: 08/28/2023] [Accepted: 09/13/2023] [Indexed: 09/25/2023] Open
Abstract
Correlated fluctuations in the blood oxygenation level dependent (BOLD) signal of resting-state functional MRI (i.e., BOLD-functional connectivity, BOLD-FC) reflect a spectrum of neuronal and non-neuronal processes. In particular, there are multiple hemodynamic-vascular influences on BOLD-FC on both systemic (e.g., perfusion delay) and local levels (e.g., neurovascular coupling). While the influence of individual factors has been studied extensively, combined and comparative studies of systemic and local hemodynamic-vascular factors on BOLD-FC are scarce, notably in humans. We employed a multi-modal MRI approach to investigate and compare distinct hemodynamic-vascular processes and their impact on homotopic BOLD-FC in healthy controls and patients with unilateral asymptomatic internal carotid artery stenosis (ICAS). Asymptomatic ICAS is a cerebrovascular disorder, in which neuronal functioning is largely preserved but hemodynamic-vascular processes are impaired, mostly on the side of stenosis. Investigated indicators for local hemodynamic-vascular processes comprise capillary transit time heterogeneity (CTH) and cerebral blood volume (CBV) from dynamic susceptibility contrast (DSC) MRI, and cerebral blood flow (CBF) from pseudo-continuous arterial spin labeling (pCASL). Indicators for systemic processes are time-to-peak (TTP) from DSC MRI and BOLD lags from functional MRI. For each of these parameters, their influence on BOLD-FC was estimated by a comprehensive linear mixed model. Equally across groups, we found that individual mean BOLD-FC, local (CTH, CBV, and CBF) and systemic (TTP and BOLD lag) hemodynamic-vascular factors together explain 40.7% of BOLD-FC variance, with 20% of BOLD-FC variance explained by hemodynamic-vascular factors, with an about two-times larger contribution of systemic versus local factors. We conclude that regional differences in blood supply, i.e., systemic perfusion delays, exert a stronger influence on BOLD-FC than impairments in local neurovascular coupling.
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Affiliation(s)
- Sebastian C Schneider
- Technical University of Munich, School of Medicine, Klinikum rechts der Isar, Clinic for Psychiatry, Ismaningerstr. 22, 81675 Munich, Germany; Technical University of Munich, School of Medicine, Klinikum rechts der Isar, TUM Neuroimaging Center, Ismaningerstr. 22, 81675 Munich, Germany; Technical University of Munich, School of Medicine, Klinikum rechts der Isar, Department of Diagnostic and Interventional Neuroradiology, Ismaningerstr. 22, 81675 Munich, Munich, Germany.
| | - Stephan Kaczmarz
- Technical University of Munich, School of Medicine, Klinikum rechts der Isar, TUM Neuroimaging Center, Ismaningerstr. 22, 81675 Munich, Germany; Technical University of Munich, School of Medicine, Klinikum rechts der Isar, Department of Diagnostic and Interventional Neuroradiology, Ismaningerstr. 22, 81675 Munich, Munich, Germany; Philips GmbH Market DACH, Hamburg, Germany
| | - Jens Göttler
- Technical University of Munich, School of Medicine, Klinikum rechts der Isar, TUM Neuroimaging Center, Ismaningerstr. 22, 81675 Munich, Germany; Technical University of Munich, School of Medicine, Klinikum rechts der Isar, Department of Diagnostic and Interventional Neuroradiology, Ismaningerstr. 22, 81675 Munich, Munich, Germany
| | - Jan Kufer
- Technical University of Munich, School of Medicine, Klinikum rechts der Isar, TUM Neuroimaging Center, Ismaningerstr. 22, 81675 Munich, Germany; Technical University of Munich, School of Medicine, Klinikum rechts der Isar, Department of Diagnostic and Interventional Neuroradiology, Ismaningerstr. 22, 81675 Munich, Munich, Germany; Department of Radiology & Biomedical Imaging, Yale University, New Haven, CT, United States of America
| | - Benedikt Zott
- Technical University of Munich, School of Medicine, Klinikum rechts der Isar, TUM Neuroimaging Center, Ismaningerstr. 22, 81675 Munich, Germany; Technical University of Munich, School of Medicine, Klinikum rechts der Isar, Department of Diagnostic and Interventional Neuroradiology, Ismaningerstr. 22, 81675 Munich, Munich, Germany
| | - Josef Priller
- Technical University of Munich, School of Medicine, Klinikum rechts der Isar, Clinic for Psychiatry, Ismaningerstr. 22, 81675 Munich, Germany
| | - Michael Kallmayer
- Technical University of Munich, School of Medicine, Klinikum rechts der Isar, Clinic for vascular surgery, Ismaningerstr. 22, 81675 Munich, Munich, Germany
| | - Claus Zimmer
- Technical University of Munich, School of Medicine, Klinikum rechts der Isar, Department of Diagnostic and Interventional Neuroradiology, Ismaningerstr. 22, 81675 Munich, Munich, Germany
| | - Christian Sorg
- Technical University of Munich, School of Medicine, Klinikum rechts der Isar, Clinic for Psychiatry, Ismaningerstr. 22, 81675 Munich, Germany; Technical University of Munich, School of Medicine, Klinikum rechts der Isar, TUM Neuroimaging Center, Ismaningerstr. 22, 81675 Munich, Germany; Technical University of Munich, School of Medicine, Klinikum rechts der Isar, Department of Diagnostic and Interventional Neuroradiology, Ismaningerstr. 22, 81675 Munich, Munich, Germany
| | - Christine Preibisch
- Technical University of Munich, School of Medicine, Klinikum rechts der Isar, TUM Neuroimaging Center, Ismaningerstr. 22, 81675 Munich, Germany; Technical University of Munich, School of Medicine, Klinikum rechts der Isar, Department of Diagnostic and Interventional Neuroradiology, Ismaningerstr. 22, 81675 Munich, Munich, Germany; Technical University of Munich, School of Medicine, Klinikum rechts der Isar, Clinic for Neurology, Ismaningerstr. 22, 81675 Munich, Munich, Germany
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3
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Korponay C, Janes AC, Frederick BB. Brain-wide functional connectivity artifactually inflates throughout fMRI scans: a problem and solution. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.08.556939. [PMID: 37745340 PMCID: PMC10515781 DOI: 10.1101/2023.09.08.556939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
The fMRI blood oxygen level-dependent (BOLD) signal is a mainstay of neuroimaging assessment of neuronal activity and functional connectivity in vivo. Thus, a chief priority is maximizing this signal's reliability and validity. To this end, the fMRI community has invested considerable effort into optimizing both experimental designs and physiological denoising procedures to improve the accuracy, across-scan reproducibility, and subject discriminability of BOLD-derived metrics like functional connectivity. Despite these advances, we discover that a substantial and ubiquitous defect remains in fMRI datasets: functional connectivity throughout the brain artifactually inflates during the course of fMRI scans - by an average of more than 70% in 15 minutes of scan time - at spatially heterogeneous rates, producing both spatial and temporal distortion of brain connectivity maps. We provide evidence that this inflation is driven by a previously unrecognized time-dependent increase of non-neuronal, systemic low-frequency oscillation (sLFO) blood flow signal during fMRI scanning. This signal is not removed by standard denoising procedures such as independent component analysis (ICA). However, we demonstrate that a specialized sLFO denoising procedure - Regressor Interpolation at Progressive Time Delays (RIPTiDe) - can be added to standard denoising pipelines to significantly attenuate functional connectivity inflation. We confirm the presence of sLFO-driven functional connectivity inflation in multiple independent fMRI datasets - including the Human Connectome Project - as well as across resting-state, task, and sleep-state conditions, and demonstrate its potential to produce false positive findings. Collectively, we present evidence for a previously unknown physiological phenomenon that spatiotemporally distorts estimates of brain connectivity in human fMRI datasets, and present a solution for mitigating this artifact.
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Affiliation(s)
- Cole Korponay
- Department of Psychiatry, Harvard University Medical School, 25 Shattuck St, Boston, MA, 02115, USA
- McLean Hospital Brain Imaging Center, 115 Mill St., Belmont, MA, 02478, USA
| | - Amy C. Janes
- Neuroimaging Research Branch, National Institute on Drug Abuse (NIDA), Intramural Research Program, National Institutes of Health, Baltimore, Maryland, USA
| | - Blaise B. Frederick
- Department of Psychiatry, Harvard University Medical School, 25 Shattuck St, Boston, MA, 02115, USA
- McLean Hospital Brain Imaging Center, 115 Mill St., Belmont, MA, 02478, USA
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4
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Gong J, Stickland RC, Bright MG. Hemodynamic timing in resting-state and breathing-task BOLD fMRI. Neuroimage 2023; 274:120120. [PMID: 37072074 DOI: 10.1016/j.neuroimage.2023.120120] [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: 11/14/2022] [Revised: 04/06/2023] [Accepted: 04/15/2023] [Indexed: 04/20/2023] Open
Abstract
The blood flow response to a vasoactive stimulus demonstrates regional heterogeneity across both the healthy brain and in cerebrovascular pathology. The timing of a regional hemodynamic response is emerging as an important biomarker of cerebrovascular dysfunction, as well as a confound within fMRI analyses. Previous research demonstrated that hemodynamic timing is more robustly characterized when a larger systemic vascular response is evoked by a breathing challenge, compared to when only spontaneous fluctuations in vascular physiology are present (i.e., in resting-state data). However, it is not clear whether hemodynamic delays in these two conditions are physiologically interchangeable, and how methodological signal-to-noise factors may limit their agreement. To address this, we generated whole-brain maps of hemodynamic delays in nine healthy adults. We assessed the agreement of voxel-wise gray matter (GM) hemodynamic delays between two conditions: resting-state and breath-holding. We found that delay values demonstrated poor agreement when considering all GM voxels, but increasingly greater agreement when limiting analyses to voxels showing strong correlation with the GM mean time-series. Voxels showing the strongest agreement with the GM mean time-series were primarily located near large venous vessels, however these voxels explain some, but not all, of the observed agreement in timing. Increasing the degree of spatial smoothing of the fMRI data enhanced the correlation between individual voxel time-series and the GM mean time-series. These results suggest that signal-to-noise factors may be limiting the accuracy of voxel-wise timing estimates and hence their agreement between the two data segments. In conclusion, caution must be taken when using voxel-wise delay estimates from resting-state and breathing-task data interchangeably, and additional work is needed to evaluate their relative sensitivity and specificity to aspects of vascular physiology and pathology.
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Affiliation(s)
- Jingxuan Gong
- Department of Biomedical Engineering, McCormick School of Engineering and Applied Sciences, Northwestern University, Evanston, IL, USA
| | - Rachael C Stickland
- Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Molly G Bright
- Department of Biomedical Engineering, McCormick School of Engineering and Applied Sciences, Northwestern University, Evanston, IL, USA; Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.
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5
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Khalil AA, Tanritanir AC, Grittner U, Kirilina E, Villringer A, Fiebach JB, Mekle R. Reproducibility of cerebral perfusion measurements using BOLD delay. Hum Brain Mapp 2023; 44:2778-2789. [PMID: 36840928 PMCID: PMC10089099 DOI: 10.1002/hbm.26244] [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: 12/03/2022] [Revised: 02/06/2023] [Accepted: 02/11/2023] [Indexed: 02/26/2023] Open
Abstract
BOLD delay is an emerging, noninvasive method for assessing cerebral perfusion that does not require the use of intravenous contrast agents and is thus particularly suited for longitudinal monitoring. In this study, we assess the reproducibility of BOLD delay using data from 136 subjects with normal cerebral perfusion scanned on two separate occasions with scanners, sequence parameters, and intervals between scans varying between subjects. The effects of various factors on the reproducibility of BOLD delay, defined here as the differences in BOLD delay values between the scanning sessions, were investigated using a linear mixed model. Reproducibility was additionally assessed using the intraclass correlation coefficient of BOLD delay between sessions. Reproducibility was highest in the posterior cerebral artery territory. The mean BOLD delay test-retest difference after accounting for the aforementioned factors was 1.2 s (95% CI = 1.0 to 1.4 s). Overall, BOLD delay shows good reproducibility, but care should be taken when interpreting longitudinal BOLD delay changes that are either very small or are located in certain brain regions.
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Affiliation(s)
- Ahmed A Khalil
- Center for Stroke Research Berlin, Charité - Universitätsmedizin Berlin, 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.,Berlin Institute of Health (BIH), Berlin, Germany
| | - Ayse C Tanritanir
- Center for Stroke Research Berlin, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Ulrike Grittner
- Berlin Institute of Health (BIH), Berlin, Germany.,Charité - Universitätsmedizin Berlin, Institute of Biometry and Clinical Epidemiology, 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
| | - 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
| | - Jochen B Fiebach
- Center for Stroke Research Berlin, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Ralf Mekle
- Center for Stroke Research Berlin, Charité - Universitätsmedizin Berlin, Berlin, Germany
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6
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Vijayakrishnan Nair V, Kish BR, Inglis B, Yang HC(S, Wright AM, Wu YC, Zhou X, Schwichtenberg AJ, Tong Y. Human CSF movement influenced by vascular low frequency oscillations and respiration. Front Physiol 2022; 13:940140. [PMID: 36060685 PMCID: PMC9437252 DOI: 10.3389/fphys.2022.940140] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Accepted: 07/11/2022] [Indexed: 12/03/2022] Open
Abstract
Cerebrospinal fluid (CSF) movement through the pathways within the central nervous system is of high significance for maintaining normal brain health and function. Low frequency hemodynamics and respiration have been shown to drive CSF in humans independently. Here, we hypothesize that CSF movement may be driven simultaneously (and in synchrony) by both mechanisms and study their independent and coupled effects on CSF movement using novel neck fMRI scans. Caudad CSF movement at the fourth ventricle and hemodynamics of the major neck blood vessels (internal carotid arteries and internal jugular veins) was measured from 11 young, healthy volunteers using novel neck fMRI scans with simultaneous measurement of respiration. Two distinct models of CSF movement (1. Low-frequency hemodynamics and 2. Respiration) and possible coupling between them were investigated. We show that the dynamics of brain fluids can be assessed from the neck by studying the interrelationships between major neck blood vessels and the CSF movement in the fourth ventricle. We also demonstrate that there exists a cross-frequency coupling between these two separable mechanisms. The human CSF system can respond to multiple coupled physiological forces at the same time. This information may help inform the pathological mechanisms behind CSF movement-related disorders.
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Affiliation(s)
| | - Brianna R. Kish
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, United States
| | - Ben Inglis
- Henry H. Wheeler, Jr. Brain Imaging Center, Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, United States
| | - Ho-Ching (Shawn) Yang
- Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Adam M. Wright
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, United States
| | - Yu-Chien Wu
- Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Xiaopeng Zhou
- School of Health Sciences, Purdue University, West Lafayette, IN, United States
| | - Amy J. Schwichtenberg
- Department of Human Development and Family Studies, College of Health and Human Sciences, Purdue University, West Lafayette, IN, United States
| | - Yunjie Tong
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, United States
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7
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Bhogal AA, Sayin ES, Poublanc J, Duffin J, Fisher JA, Sobcyzk O, Mikulis DJ. Quantifying cerebral blood arrival times using hypoxia-mediated arterial BOLD contrast. Neuroimage 2022; 261:119523. [PMID: 35907499 DOI: 10.1016/j.neuroimage.2022.119523] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 07/20/2022] [Accepted: 07/25/2022] [Indexed: 11/19/2022] Open
Abstract
Cerebral blood arrival and tissue transit times are sensitive measures of the efficiency of tissue perfusion and can provide clinically meaningful information on collateral blood flow status. We exploit the arterial blood oxygen level dependent (BOLD) signal contrast established by precisely decreasing, and then increasing, arterial hemoglobin saturation using respiratory re-oxygenation challenges to quantify arterial blood arrival times throughout the brain. We term this approach the Step Hemoglobin re-Oxygenation Contrast Stimulus (SHOCS). Carpet plot analysis yielded measures of signal onset (blood arrival), global transit time (gTT) and calculations of relative total blood volume. Onset times averaged across 12 healthy subjects were 1.1 ± 0.4 and 1.9 ± 0.6 for cortical gray and deep white matter, respectively. The average whole brain gTT was 4.5 ± 0.9 seconds. The SHOCS response was 1.7 fold higher in grey versus white matter; in line with known differences in tissue-specific blood volume fraction. SHOCS was also applied in a patient with unilateral carotid artery occlusion revealing ipsilateral prolonged signal onset with normal perfusion in the unaffected hemisphere. We anticipate that SHOCS will further inform on the extent of collateral blood flow in patients with upstream steno-occlusive vascular disease, including those already known to manifest reductions in vasodilatory reserve capacity or vascular steal.
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Affiliation(s)
- Alex A Bhogal
- Center of Imaging Sciences, High Field Department, University Medical Center Utrecht, Heidelberglaan 100, Utrecht, CX 3584, the Netherlands.
| | - Ece Su Sayin
- Department of Physiology, University of Toronto, Toronto, Canada
| | - Julien Poublanc
- Joint Department of Medical Imaging and the Functional Neuroimaging Lab, University Health Network, Toronto, ON, Canada
| | - James Duffin
- Department of Physiology, University of Toronto, Toronto, Canada; Toronto General Hospital Research Institute, Toronto, Canada
| | - Joseph A Fisher
- Department of Physiology, University of Toronto, Toronto, Canada; Department of Anesthesiology and Pain Medicine, University Health Network and University of Toronto, Toronto, Canada
| | - Olivia Sobcyzk
- Joint Department of Medical Imaging and the Functional Neuroimaging Lab, University Health Network, Toronto, ON, Canada; Department of Anesthesiology and Pain Medicine, University Health Network and University of Toronto, Toronto, Canada
| | - David J Mikulis
- Joint Department of Medical Imaging and the Functional Neuroimaging Lab, University Health Network, Toronto, ON, Canada
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8
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Noda T, Isobe M, Ueda K, Aso T, Murao E, Kawabata M, Noma S, Murai T. The relationship between attention and avoidance coping in anorexia nervosa: functional magnetic resonance imaging study. BJPsych Open 2021; 7:e130. [PMID: 34253276 PMCID: PMC8281280 DOI: 10.1192/bjo.2021.963] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Numerous studies have demonstrated attentional control difficulties and high avoidance coping in patients with anorexia nervosa. Attention is a critical coping resource because it enables individuals to demonstrate self-control and complete goal-directed behaviours. AIMS We aimed to examine whether attentional control difficulty is related to high avoidance coping, and investigate the neural underpinnings of attentional control difficulties in individuals with anorexia nervosa. METHOD Twenty-three patients with anorexia nervosa and 17 healthy controls completed questionnaires that assessed attention and coping, and underwent functional magnetic resonance imaging while performing a go/no-go task. RESULTS Patients with anorexia nervosa showed weaker attentional control, higher omission error rates and higher avoidance coping compared with healthy controls. Attentional control difficulty was associated with higher avoidance coping in both groups. Functional magnetic resonance imaging analysis showed less deactivation in regions representing internal mental processing, such as the praecuneus, cuneus and left lingual gyrus, during the no-go condition. Moreover, weakened deactivation of the left lingual gyrus was associated with higher commission error rate in the anorexia nervosa group. CONCLUSIONS Our results suggest that patients with anorexia nervosa may have difficulty in maintaining attention to external ongoing events because of disturbance from internal self-related thought, and support the notion that attentional control difficulties underlie the frequent use of avoidance coping in anorexia nervosa.
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Affiliation(s)
- Tomomi Noda
- Department of Psychiatry, Kyoto University Graduate School of Medicine, Japan
| | - Masanori Isobe
- Department of Psychiatry, Kyoto University Graduate School of Medicine, Japan
| | - Keita Ueda
- Department of Psychiatry, Kyoto University Graduate School of Medicine, Japan
| | - Toshihiko Aso
- Laboratory for Brain Connectomics Imaging, RIKEN Center for Biosystems Dynamics Research, Japan
| | - Ema Murao
- Department of Psychiatry, Saga-Sakura Hospital, Japan
| | - Michiko Kawabata
- Department of Psychiatry, Kyoto University Graduate School of Medicine, Japan
| | - Shun'ichi Noma
- Department of Psychiatry, Nomakokoro Clinic, Japan; and Department of Psychiatry, Kyoto University Graduate School of Medicine, Japan
| | - Toshiya Murai
- Department of Psychiatry, Kyoto University Graduate School of Medicine, Japan
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9
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Chen JJ, Gauthier CJ. The Role of Cerebrovascular-Reactivity Mapping in Functional MRI: Calibrated fMRI and Resting-State fMRI. Front Physiol 2021; 12:657362. [PMID: 33841190 PMCID: PMC8027080 DOI: 10.3389/fphys.2021.657362] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 03/02/2021] [Indexed: 12/14/2022] Open
Abstract
Task and resting-state functional MRI (fMRI) is primarily based on the same blood-oxygenation level-dependent (BOLD) phenomenon that MRI-based cerebrovascular reactivity (CVR) mapping has most commonly relied upon. This technique is finding an ever-increasing role in neuroscience and clinical research as well as treatment planning. The estimation of CVR has unique applications in and associations with fMRI. In particular, CVR estimation is part of a family of techniques called calibrated BOLD fMRI, the purpose of which is to allow the mapping of cerebral oxidative metabolism (CMRO2) using a combination of BOLD and cerebral-blood flow (CBF) measurements. Moreover, CVR has recently been shown to be a major source of vascular bias in computing resting-state functional connectivity, in much the same way that it is used to neutralize the vascular contribution in calibrated fMRI. Furthermore, due to the obvious challenges in estimating CVR using gas challenges, a rapidly growing field of study is the estimation of CVR without any form of challenge, including the use of resting-state fMRI for that purpose. This review addresses all of these aspects in which CVR interacts with fMRI and the role of CVR in calibrated fMRI, provides an overview of the physiological biases and assumptions underlying hypercapnia-based CVR and calibrated fMRI, and provides a view into the future of non-invasive CVR measurement.
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Affiliation(s)
- J Jean Chen
- Baycrest Centre for Geriatric Care, Rotman Research Institute, Toronto, ON, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada
| | - Claudine J Gauthier
- Department of Physics, Concordia University, Montreal, QC, Canada.,Montreal Heart Institute, Montreal, QC, Canada
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10
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Cook PF, Hoard VA, Dolui S, Frederick BD, Redfern R, Dennison SE, Halaska B, Bloom J, Kruse-Elliott KT, Whitmer ER, Trumbull EJ, Berns GS, Detre JA, D'Esposito M, Gulland FMD, Reichmuth C, Johnson SP, Field CL, Inglis BA. An MRI protocol for anatomical and functional evaluation of the California sea lion brain. J Neurosci Methods 2021; 353:109097. [PMID: 33581216 DOI: 10.1016/j.jneumeth.2021.109097] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 01/29/2021] [Accepted: 02/04/2021] [Indexed: 12/14/2022]
Abstract
BACKGROUND Domoic acid (DOM) is a neurotoxin produced by some harmful algae blooms in coastal waters. California sea lions (Zalophus californianus) exposed to DOM often strand on beaches where they exhibit a variety of symptoms, including seizures. These animals typically show hippocampal atrophy on MRI scans. NEW METHOD We describe an MRI protocol for comprehensive evaluation of DOM toxicosis in the sea lion brain. We intend to study brain development in pups exposed in utero. The protocol depicts the hippocampal formation as the primary region of interest. We include scans for quantitative morphometry, functional and structural connectivity, and a cerebral blood flow map. RESULTS High-resolution 3D anatomical scans facilitate post hoc slicing in arbitrary planes and accurate morphometry. We demonstrate the first cerebral blood flow map using MRI, and the first structural tractography from a live sea lion brain. COMPARISON WITH EXISTING METHODS Scans were compared to prior anatomical and functional studies in live sea lions, and structural connectivity in post mortem specimens. Hippocampal volumes were broadly in line with prior studies, with differences likely attributable to the 3D approach used here. Functional connectivity of the dorsal left hippocampus matched that found in a prior study conducted at a lower magnetic field, while structural connectivity in the live brain agreed with findings observed in post mortem studies. CONCLUSIONS Our protocol provides a comprehensive, longitudinal view of the functional and anatomical changes expected to result from DOM toxicosis. It can also screen for other common neurological pathologies and is suitable for any pinniped that can fit inside an MRI scanner.
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Affiliation(s)
- Peter F Cook
- Department of Biopsychology, New College of Florida, 5800 Bay Shore Road, Sarasota, FL, 34243, USA
| | - Vanessa A Hoard
- The Marine Mammal Center, 2000 Bunker Road, Sausalito, CA, 94965, USA
| | - Sudipto Dolui
- Department of Radiology, University of Pennsylvania Perelman School of Medicine, 3400 Spruce Street, Philadelphia, PA, 19104, USA
| | - Blaise deB Frederick
- Department of Psychiatry, Harvard University Medical School, 25 Shattuck St, Boston, MA, 02115, USA; McLean Hospital Brain Imaging Center, 115 Mill St., Belmont, MA, 02478, USA
| | - Richard Redfern
- Henry H. Wheeler, Jr. Brain Imaging Center, 188 Li Ka Shing Center for Biomedical and Health Sciences, University of California, Berkeley, CA, 94720, USA
| | | | - Barbie Halaska
- The Marine Mammal Center, 2000 Bunker Road, Sausalito, CA, 94965, USA
| | - Josh Bloom
- AnimalScan Advanced Veterinary Imaging, 934 Charter St, Redwood City, CA, 94063, USA
| | - Kris T Kruse-Elliott
- AnimalScan Advanced Veterinary Imaging, 934 Charter St, Redwood City, CA, 94063, USA
| | - Emily R Whitmer
- The Marine Mammal Center, 2000 Bunker Road, Sausalito, CA, 94965, USA
| | - Emily J Trumbull
- The Marine Mammal Center, 2000 Bunker Road, Sausalito, CA, 94965, USA
| | - Gregory S Berns
- Psychology Department, Emory University, 36 Eagle Row, Atlanta, GA, 30322, USA
| | - John A Detre
- Department of Radiology, University of Pennsylvania Perelman School of Medicine, 3400 Spruce Street, Philadelphia, PA, 19104, USA; Department of Neurology, University of Pennsylvania, 3400 Spruce St, Philadelphia, PA, 19104, USA
| | - Mark D'Esposito
- Henry H. Wheeler, Jr. Brain Imaging Center, 188 Li Ka Shing Center for Biomedical and Health Sciences, University of California, Berkeley, CA, 94720, USA; Helen Wills Neuroscience Institute, University of California, 132 Barker Hall, Berkeley, CA, 94720, USA
| | - Frances M D Gulland
- School of Veterinary Medicine Wildlife Health Center, University of California at Davis, 1089 Veterinary Medicine Dr, Davis, CA, 95616, USA
| | - Colleen Reichmuth
- Long Marine Laboratory, Institute of Marine Sciences, University of California at Santa Cruz, 115 McAllister Way, Santa Cruz, CA, 95060, USA
| | - Shawn P Johnson
- The Marine Mammal Center, 2000 Bunker Road, Sausalito, CA, 94965, USA
| | - Cara L Field
- The Marine Mammal Center, 2000 Bunker Road, Sausalito, CA, 94965, USA
| | - Ben A Inglis
- Henry H. Wheeler, Jr. Brain Imaging Center, 188 Li Ka Shing Center for Biomedical and Health Sciences, University of California, Berkeley, CA, 94720, USA.
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11
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Aso T, Sugihara G, Murai T, Ubukata S, Urayama SI, Ueno T, Fujimoto G, Thuy DHD, Fukuyama H, Ueda K. A venous mechanism of ventriculomegaly shared between traumatic brain injury and normal ageing. Brain 2021; 143:1843-1856. [PMID: 32372102 PMCID: PMC7296851 DOI: 10.1093/brain/awaa125] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 02/18/2020] [Accepted: 03/01/2020] [Indexed: 11/15/2022] Open
Abstract
Recently, age-related timing dissociation between the superficial and deep venous systems has been observed; this was particularly pronounced in patients with normal pressure hydrocephalus, suggesting a common mechanism of ventriculomegaly. Establishing the relationship between venous drainage and ventricular enlargement would be clinically relevant and could provide insight into the mechanisms underlying brain ageing. To investigate a possible link between venous drainage and ventriculomegaly in both normal ageing and pathological conditions, we compared 225 healthy subjects (137 males and 88 females) and 71 traumatic brain injury patients of varying ages (53 males and 18 females) using MRI-based volumetry and a novel perfusion-timing analysis. Volumetry, focusing on the CSF space, revealed that the sulcal space and ventricular size presented different lifespan profiles with age; the latter presented a quadratic, rather than linear, pattern of increase. The venous timing shift slightly preceded this change, supporting a role for venous drainage in ventriculomegaly. In traumatic brain injury, a small but significant disease effect, similar to idiopathic normal pressure hydrocephalus, was found in venous timing, but it tended to decrease with age at injury, suggesting an overlapping mechanism with normal ageing. Structural bias due to, or a direct causative role of ventriculomegaly was unlikely to play a dominant role, because of the low correlation between venous timing and ventricular size after adjustment for age in both patients and controls. Since post-traumatic hydrocephalus can be asymptomatic and occasionally overlooked, the observation suggested a link between venous drainage and CSF accumulation. Thus, hydrocephalus, involving venous insufficiency, may be a part of normal ageing, can be detected non-invasively, and is potentially treatable. Further investigation into the clinical application of this new marker of venous function is therefore warranted.
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Affiliation(s)
- Toshihiko Aso
- Department of Psychiatry, Kyoto University Graduate School of Medicine, Kyoto, Japan.,Laboratory for Brain Connectomics Imaging, RIKEN Center for Biosystems Dynamics Research, Kobe, Japan.,Human Brain Research Center, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Genichi Sugihara
- Department of Psychiatry, Kyoto University Graduate School of Medicine, Kyoto, Japan.,Department of Psychiatry and Behavioral Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Toshiya Murai
- Department of Psychiatry, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Shiho Ubukata
- Department of Psychiatry, Kyoto University Graduate School of Medicine, Kyoto, Japan.,Medical Innovation Center, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Shin-Ichi Urayama
- Human Brain Research Center, Kyoto University Graduate School of Medicine, Kyoto, Japan.,Research and Educational Unit of Leaders for Integrated Medical System, Center for the Promotion of Interdisciplinary Education and Research, Kyoto University, Kyoto, Japan
| | - Tsukasa Ueno
- Department of Psychiatry, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Gaku Fujimoto
- Department of Psychiatry, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Dinh Ha Duy Thuy
- Human Brain Research Center, Kyoto University Graduate School of Medicine, Kyoto, Japan.,Research and Educational Unit of Leaders for Integrated Medical System, Center for the Promotion of Interdisciplinary Education and Research, Kyoto University, Kyoto, Japan
| | - Hidenao Fukuyama
- Human Brain Research Center, Kyoto University Graduate School of Medicine, Kyoto, Japan.,Research and Educational Unit of Leaders for Integrated Medical System, Center for the Promotion of Interdisciplinary Education and Research, Kyoto University, Kyoto, Japan
| | - Keita Ueda
- Department of Psychiatry, Kyoto University Graduate School of Medicine, Kyoto, Japan
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12
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Das A, Murphy K, Drew PJ. Rude mechanicals in brain haemodynamics: non-neural actors that influence blood flow. Philos Trans R Soc Lond B Biol Sci 2021; 376:20190635. [PMID: 33190603 PMCID: PMC7741032 DOI: 10.1098/rstb.2019.0635] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/15/2020] [Indexed: 01/10/2023] Open
Abstract
Fluctuations in blood oxygenation and flow are widely used to infer brain activity during resting-state functional magnetic resonance imaging (fMRI). However, there are strong systemic and vascular contributions to resting-state signals that are unrelated to ongoing neural activity. Importantly, these non-neural contributions to haemodynamic signals (or 'rude mechanicals') can be as large as or larger than the neurally evoked components. Here, we review the two broad classes of drivers of these signals. One is systemic and is tied to fluctuations in external drivers such as heart rate and breathing, and the robust autoregulatory mechanisms that try to maintain a constant milieu in the brain. The other class comprises local, active fluctuations that appear to be intrinsic to vascular tissue and are likely similar to active local fluctuations seen in vasculature all over the body. In this review, we describe these non-neural fluctuations and some of the tools developed to correct for them when interpreting fMRI recordings. However, we also emphasize the links between these vascular fluctuations and brain physiology and point to ways in which fMRI measurements can be used to exploit such links to gain valuable information about neurovascular health and about internal brain states. This article is part of the theme issue 'Key relationships between non-invasive functional neuroimaging and the underlying neuronal activity'.
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Affiliation(s)
- Aniruddha Das
- Department of Neuroscience, Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY 10027, USA
| | - Kevin Murphy
- Cardiff University Brain Research Imaging Centre (CUBRIC), School of Physics and Astronomy, Cardiff University, Cardiff CF24 4HQ, UK
| | - Patrick J. Drew
- Departments of Engineering Science and Mechanics, Neurosurgery, and Biomedical Engineering, The Pennsylvania State University, University Park, PA 16802, USA
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13
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Aso T, Sugihara G, Murai T, Ubukata S, Urayama SI, Ueno T, Fujimoto G, Thuy DHD, Fukuyama H, Ueda K. Reply: A transvenous pressure gradient mechanism behind ventriculomegaly. Brain 2020; 143:e75. [PMID: 32945879 DOI: 10.1093/brain/awaa271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Toshihiko Aso
- Department of Psychiatry, Kyoto University Graduate School of Medicine, Kyoto, Japan.,Laboratory for Brain Connectomics Imaging, RIKEN Center for Biosystems Dynamics Research, Kobe, Japan.,Human Brain Research Center, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Genichi Sugihara
- Department of Psychiatry, Kyoto University Graduate School of Medicine, Kyoto, Japan.,Department of Psychiatry and Behavioral Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Toshiya Murai
- Department of Psychiatry, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Shiho Ubukata
- Department of Psychiatry, Kyoto University Graduate School of Medicine, Kyoto, Japan.,Medical Innovation Center, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Shin-Ichi Urayama
- Human Brain Research Center, Kyoto University Graduate School of Medicine, Kyoto, Japan.,Research and Educational Unit of Leaders for Integrated Medical System, Center for the Promotion of Interdisciplinary Education and Research, Kyoto University, Kyoto, Japan
| | - Tsukasa Ueno
- Department of Psychiatry, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Gaku Fujimoto
- Department of Psychiatry, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Dinh Ha Duy Thuy
- Human Brain Research Center, Kyoto University Graduate School of Medicine, Kyoto, Japan.,Research and Educational Unit of Leaders for Integrated Medical System, Center for the Promotion of Interdisciplinary Education and Research, Kyoto University, Kyoto, Japan
| | - Hidenao Fukuyama
- Human Brain Research Center, Kyoto University Graduate School of Medicine, Kyoto, Japan.,Research and Educational Unit of Leaders for Integrated Medical System, Center for the Promotion of Interdisciplinary Education and Research, Kyoto University, Kyoto, Japan
| | - Keita Ueda
- Department of Psychiatry, Kyoto University Graduate School of Medicine, Kyoto, Japan
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14
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Fallon J, Ward PGD, Parkes L, Oldham S, Arnatkevičiūtė A, Fornito A, Fulcher BD. Timescales of spontaneous fMRI fluctuations relate to structural connectivity in the brain. Netw Neurosci 2020; 4:788-806. [PMID: 33615091 PMCID: PMC7888482 DOI: 10.1162/netn_a_00151] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 06/08/2020] [Indexed: 12/21/2022] Open
Abstract
Intrinsic timescales of activity fluctuations vary hierarchically across the brain. This variation reflects a broad gradient of functional specialization in information storage and processing, with integrative association areas displaying slower timescales that are thought to reflect longer temporal processing windows. The organization of timescales is associated with cognitive function, distinctive between individuals, and disrupted in disease, but we do not yet understand how the temporal properties of activity dynamics are shaped by the brain's underlying structural connectivity network. Using resting-state fMRI and diffusion MRI data from 100 healthy individuals from the Human Connectome Project, here we show that the timescale of resting-state fMRI dynamics increases with structural connectivity strength, matching recent results in the mouse brain. Our results hold at the level of individuals, are robust to parcellation schemes, and are conserved across a range of different timescale- related statistics. We establish a comprehensive BOLD dynamical signature of structural connectivity strength by comparing over 6,000 time series features, highlighting a range of new temporal features for characterizing BOLD dynamics, including measures of stationarity and symbolic motif frequencies. Our findings indicate a conserved property of mouse and human brain organization in which a brain region's spontaneous activity fluctuations are closely related to their surrounding structural scaffold.
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Affiliation(s)
- John Fallon
- Turner Institute for Brain and Mental Health, School of Psychological Sciences, and Monash Biomedical Imaging, Monash University, Victoria, Australia
| | - Phillip G. D. Ward
- Turner Institute for Brain and Mental Health, School of Psychological Sciences, and Monash Biomedical Imaging, Monash University, Victoria, Australia
- Australian Research Council Centre of Excellence for Integrative Brain Function, Melbourne, Australia
| | - Linden Parkes
- Turner Institute for Brain and Mental Health, School of Psychological Sciences, and Monash Biomedical Imaging, Monash University, Victoria, Australia
- Department of Bioengineering, School of Engineering & Applied Science, University of Pennsylvania, Philadelphia, PA, 19104 USA
| | - Stuart Oldham
- Turner Institute for Brain and Mental Health, School of Psychological Sciences, and Monash Biomedical Imaging, Monash University, Victoria, Australia
| | - Aurina Arnatkevičiūtė
- Turner Institute for Brain and Mental Health, School of Psychological Sciences, and Monash Biomedical Imaging, Monash University, Victoria, Australia
| | - Alex Fornito
- Turner Institute for Brain and Mental Health, School of Psychological Sciences, and Monash Biomedical Imaging, Monash University, Victoria, Australia
| | - Ben D. Fulcher
- Australian Research Council Centre of Excellence for Integrative Brain Function, Melbourne, Australia
- School of Physics, University of Sydney, NSW, Australia
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15
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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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16
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Aso T, Urayama S, Fukuyama H, Murai T. Correction: Axial variation of deoxyhemoglobin density as a source of the low-frequency time lag structure in blood oxygenation level-dependent signals. PLoS One 2019; 14:e0225489. [PMID: 31725801 PMCID: PMC6855433 DOI: 10.1371/journal.pone.0225489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
[This corrects the article DOI: 10.1371/journal.pone.0222787.].
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