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Xu F, Xu C, Zhu D, Liu D, Lu H, Qin Q. Evaluating cerebrovascular reactivity measured by velocity selective inversion arterial spin labeling with different post-labeling delays: The effect of fast flow. Magn Reson Med 2024; 92:2065-2073. [PMID: 38852173 PMCID: PMC11341248 DOI: 10.1002/mrm.30166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2024] [Revised: 04/24/2024] [Accepted: 05/08/2024] [Indexed: 06/11/2024]
Abstract
PURPOSE Velocity selective arterial spin labeling (VSASL) quantification assumes that the labeled bolus continuously moves into the imaging voxel during the post-labeling delay (PLD). Faster blood flow could lead to a bolus duration shorter than the applied PLD of VSASL and cause underestimation of cerebral blood flow (CBF). This study aims to evaluate the performance of velocity-selective inversion (VSI) prepared arterial spin labeling (ASL) with different PLDs and pseudo-continuous ASL (PCASL) for quantification of hypercapnia-induced cerebrovascular reactivity (CVR), using phase-contrast (PC) MRI as a global reference. METHODS We compared CVR obtained by VSI-ASL with PLD of 1520 ms (VSASL-1520), 1000 ms (VSASL-1000), and 500 ms (VSASL-500), PCASL with PLD of 1800 ms (PCASL-1800), and PC MRI on eight healthy volunteers at two sessions. RESULTS Compared with PC MRI, VSASL-1520 produced significantly lower global CVR values, while PCASL-1800, VSASL-1000, and VSASL-500 yielded more consistent results. The reduced CVR in VSASL-1520 was more pronounced in carotid territories including frontal and temporal lobes than in vertebral territories such as the occipital lobe. This is largely caused by the underestimated perfusion during hypercapnia due to the reduced bolus duration being less than the PLD. CONCLUSION Although VSASL offers certain advantages over spatially selective ASL due to its reduced susceptibility to delayed ATT, this technique is prone to biases when the ATT is excessively short. Therefore, a short PLD should be employed for reliable perfusion and CVR quantification in populations or conditions with fast flow.
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Affiliation(s)
- Feng Xu
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD, USA
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
| | - Cuimei Xu
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD, USA
| | - Dan Zhu
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD, USA
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
| | - Dapeng Liu
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD, USA
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
| | - Hanzhang Lu
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD, USA
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
| | - Qin Qin
- The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD, USA
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
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Libecap T, Bauer CE, Zachariou V, Pappas CA, Raslau FD, Liu P, Lu H, Gold BT. Association of Baseline Cerebrovascular Reactivity and Longitudinal Development of Enlarged Perivascular Spaces in the Basal Ganglia. Stroke 2023; 54:2785-2793. [PMID: 37712232 PMCID: PMC10615859 DOI: 10.1161/strokeaha.123.043882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Accepted: 08/24/2023] [Indexed: 09/16/2023]
Abstract
BACKGROUND Increasing evidence suggests that enlarged perivascular spaces (ePVS) are associated with cognitive dysfunction in aging. However, the pathogenesis of ePVS remains unknown. Here, we tested the possibility that baseline cerebrovascular dysfunction, as measured by a magnetic resonance imaging measure of cerebrovascular reactivity, contributes to the later development of ePVS. METHODS Fifty cognitively unimpaired, older adults (31 women; age range, 60-84 years) underwent magnetic resonance imaging scanning at baseline and follow-up separated by ≈2.5 years. ePVS were counted in the basal ganglia, centrum semiovale, midbrain, and hippocampus. Cerebrovascular reactivity, an index of the vasodilatory capacity of cerebral small vessels, was assessed using carbon dioxide inhalation while acquiring blood oxygen level-dependent magnetic resonance images. RESULTS Low baseline cerebrovascular reactivity values in the basal ganglia were associated with increased follow-up ePVS counts in the basal ganglia after controlling for age, sex, and baseline ePVS values (estimate [SE]=-3.18 [0.96]; P=0.002; [95% CI, -5.11 to -1.24]). This effect remained significant after accounting for self-reported risk factors of cerebral small vessel disease (estimate [SE]=-3.10 [1.00]; P=0.003; [CI, -5.11 to -1.09]) and neuroimaging markers of cerebral small vessel disease (estimate [SE]=-2.72 [0.99]; P=0.009; [CI, -4.71 to -0.73]). CONCLUSIONS Our results demonstrate that low baseline cerebrovascular reactivity is a risk factor for later development of ePVS.
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Affiliation(s)
- T.J. Libecap
- Department of Neuroscience, University of Kentucky College of Medicine, Lexington, Kentucky, USA
| | - Christopher E. Bauer
- Department of Neuroscience, University of Kentucky College of Medicine, Lexington, Kentucky, USA
| | - Valentinos Zachariou
- Department of Neuroscience, University of Kentucky College of Medicine, Lexington, Kentucky, USA
| | - Colleen A. Pappas
- Department of Neuroscience, University of Kentucky College of Medicine, Lexington, Kentucky, USA
| | - Flavius D. Raslau
- Department of Radiology, University of Kentucky College of Medicine, Lexington, Kentucky, USA
| | - Peiying Liu
- Department of Radiology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Hanzhang Lu
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Brian T. Gold
- Department of Neuroscience, University of Kentucky College of Medicine, Lexington, Kentucky, USA
- Department of Radiology, University of Kentucky College of Medicine, Lexington, Kentucky, USA
- Magnetic Resonance Imaging and Spectroscopy Center, University of Kentucky, Lexington, Kentucky, USA
- Sanders-Brown Center on Aging University of Kentucky, Lexington, Kentucky, USA
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3
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Cowdrick KR, Urner T, Sathialingam E, Fang Z, Quadri A, Turrentine K, Yup Lee S, Buckley EM. Agreement in cerebrovascular reactivity assessed with diffuse correlation spectroscopy across experimental paradigms improves with short separation regression. NEUROPHOTONICS 2023; 10:025002. [PMID: 37034012 PMCID: PMC10079775 DOI: 10.1117/1.nph.10.2.025002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 03/07/2023] [Indexed: 06/19/2023]
Abstract
Significance Cerebrovascular reactivity (CVR), i.e., the ability of cerebral vasculature to dilate or constrict in response to vasoactive stimuli, is a biomarker of vascular health. Exogenous administration of inhaled carbon dioxide, i.e., hypercapnia (HC), remains the "gold-standard" intervention to assess CVR. More tolerable paradigms that enable CVR quantification when HC is difficult/contraindicated have been proposed. However, because these paradigms feature mechanistic differences in action, an assessment of agreement of these more tolerable paradigms to HC is needed. Aim We aim to determine the agreement of CVR assessed during HC, breath-hold (BH), and resting state (RS) paradigms. Approach Healthy adults were subject to HC, BH, and RS paradigms. End tidal carbon dioxide (EtCO2) and cerebral blood flow (CBF, assessed with diffuse correlation spectroscopy) were monitored continuously. CVR (%/mmHg) was quantified via linear regression of CBF versus EtCO2 or via a general linear model (GLM) that was used to minimize the influence of systemic and extracerebral signal contributions. Results Strong agreement ( CCC ≥ 0.69 ; R ≥ 0.76 ) among CVR paradigms was demonstrated when utilizing a GLM to regress out systemic/extracerebral signal contributions. Linear regression alone showed poor agreement across paradigms ( CCC ≤ 0.35 ; R ≤ 0.45 ). Conclusions More tolerable experimental paradigms coupled with regression of systemic/extracerebral signal contributions may offer a viable alternative to HC for assessing CVR.
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Affiliation(s)
- Kyle R. Cowdrick
- Georgia Institute of Technology and Emory University, Wallace H. Coulter Department of Biomedical Engineering, Atlanta, Georgia, United States
| | - Tara Urner
- Georgia Institute of Technology and Emory University, Wallace H. Coulter Department of Biomedical Engineering, Atlanta, Georgia, United States
| | - Eashani Sathialingam
- Georgia Institute of Technology and Emory University, Wallace H. Coulter Department of Biomedical Engineering, Atlanta, Georgia, United States
| | - Zhou Fang
- Georgia Institute of Technology and Emory University, Wallace H. Coulter Department of Biomedical Engineering, Atlanta, Georgia, United States
| | - Ayesha Quadri
- Children’s Healthcare of Atlanta and Emory University School of Medicine, Department of Pediatrics, Atlanta, Georgia, United States
- Morehouse School of Medicine, Atlanta, Georgia, United States
| | - Katherine Turrentine
- Children’s Healthcare of Atlanta and Emory University School of Medicine, Department of Pediatrics, Atlanta, Georgia, United States
| | - Seung Yup Lee
- Georgia Institute of Technology and Emory University, Wallace H. Coulter Department of Biomedical Engineering, Atlanta, Georgia, United States
- Kennesaw State University, Department of Electrical and Computer Engineering, Marietta, Georgia, United States
| | - Erin M. Buckley
- Georgia Institute of Technology and Emory University, Wallace H. Coulter Department of Biomedical Engineering, Atlanta, Georgia, United States
- Children’s Healthcare of Atlanta and Emory University School of Medicine, Department of Pediatrics, Atlanta, Georgia, United States
- Children’s Healthcare of Atlanta, Children’s Research Scholar, Atlanta, Georgia, United States
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Amyot F, Davis C, Sangobowale M, Moore C, Silverman E, Gandjbakhche A, Diaz-Arrastia R, Kenney K. Cerebrovascular Reactivity Measurement with Functional Near Infrared Spectroscopy. J Vis Exp 2022:10.3791/61284. [PMID: 35723463 PMCID: PMC11189107 DOI: 10.3791/61284] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/22/2024] Open
Abstract
Cerebrovascular reactivity (CVR) is the capacity of blood vessels in the brain to alter cerebral blood flow (either with dilation or constriction) in response to chemical or physical stimuli. The amount of reactivity in the cerebral microvasculature depends on the integrity of the capacitance vasculature and is the primary function of endothelial cells. CVR is, therefore, an indicator of the microvasculature's physiology and overall health. Imaging methods that can measure CVR are available but can be costly, and require magnetic resonance imaging centers and technical expertise. In this study, we used fNIRS technology to monitor changes of oxyhemoglobin (HbO) and deoxyhemoglobin (HbR) in the cerebral microvasculature to assess the CVR of 15 healthy controls (HC) in response to a vasoactive stimulus (inhaled 5% carbon dioxide or CO2). Our results suggest that this is a promising imaging technology that offers a non-invasive, accurate, portable, and cost-effective method of mapping cortical CVR and associated microvasculature function, resulting from a traumatic brain injury or other conditions associated with cerebral microvasculopathy.
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Affiliation(s)
- Franck Amyot
- National Intrepid Center of Excellence, Walter Reed National Military Medical Center;
| | - Cora Davis
- National Intrepid Center of Excellence, Walter Reed National Military Medical Center
| | | | - Carol Moore
- Uniformed Services University of the Health Sciences
| | | | - Amir Gandjbakhche
- The Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health
| | | | - Kimbra Kenney
- National Intrepid Center of Excellence, Walter Reed National Military Medical Center; Uniformed Services University of the Health Sciences
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5
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Chan RW, Won Bang J, Trivedi V, Murphy MC, Liu P, Wollstein G, Schuman JS, Chan KC. Relationships between cerebrovascular reactivity, visual-evoked functional activity, and resting-state functional connectivity in the visual cortex and basal forebrain in glaucoma. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2021; 2021:4037-4040. [PMID: 34892116 PMCID: PMC9218998 DOI: 10.1109/embc46164.2021.9630904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Glaucoma is primarily considered an eye disease with widespread involvements of the brain. Yet, it remains unclear how cerebrovasculature is regulated in glaucoma and how different brain regions coordinate functionally across disease severity. To address these questions, we applied a novel whole-brain relative cerebrovascular reactivity (rCVR) mapping technique using resting-state functional magnetic resonance imaging (fMRI) without gas challenges to 38 glaucoma patients and 21 healthy subjects. The relationships between rCVR, visual-evoked fMRI response, and resting-state functional connectivity in glaucoma were then established. In the visual cortex, rCVR has a decreasing trend with glaucoma severity (p<0.05), and is coupled with visual-evoked response and functional connectivity in both hemispheres (p<0.001). Interestingly, rCVR in the basal forebrain (BF) has an increasing trend with glaucoma severity (p<0.05). The functional connectivity between right diagonal band of Broca (a sub-region of BF) and lateral visual cortex decreases with glaucoma (p<0.05), while such connectivity is inversely coupled with rCVR in the BF (p<0.05), but not the visual cortex. Overall, we demonstrate opposite trends of rCVR changes in the visual cortex and BF in glaucoma patients, suggestive of compensatory actions in vascular reserve between the two brain regions. The neurovascular coupling within the visual cortex appears deteriorated in glaucoma, whereas the association between BF-visual cortex functional connectivity and rCVR of BF indicates the functional and vascular involvements in glaucoma beyond the primary visual pathway.
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Haber M, Amyot F, Lynch CE, Sandsmark DK, Kenney K, Werner JK, Moore C, Flesher K, Woodson S, Silverman E, Chou Y, Pham D, Diaz-Arrastia R. Imaging biomarkers of vascular and axonal injury are spatially distinct in chronic traumatic brain injury. J Cereb Blood Flow Metab 2021; 41:1924-1938. [PMID: 33444092 PMCID: PMC8327117 DOI: 10.1177/0271678x20985156] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 10/07/2020] [Accepted: 12/06/2020] [Indexed: 11/17/2022]
Abstract
Traumatic Brain Injury (TBI) is associated with both diffuse axonal injury (DAI) and diffuse vascular injury (DVI), which result from inertial shearing forces. These terms are often used interchangeably, but the spatial relationships between DAI and DVI have not been carefully studied. Multimodal magnetic resonance imaging (MRI) can help distinguish these injury mechanisms: diffusion tensor imaging (DTI) provides information about axonal integrity, while arterial spin labeling (ASL) can be used to measure cerebral blood flow (CBF), and the reactivity of the Blood Oxygen Level Dependent (BOLD) signal to a hypercapnia challenge reflects cerebrovascular reactivity (CVR). Subjects with chronic TBI (n = 27) and healthy controls (n = 14) were studied with multimodal MRI. Mean values of mean diffusivity (MD), fractional anisotropy (FA), CBF, and CVR were extracted for pre-determined regions of interest (ROIs). Normalized z-score maps were generated from the pool of healthy controls. Abnormal ROIs in one modality were not predictive of abnormalities in another. Approximately 9-10% of abnormal voxels for CVR and CBF also showed an abnormal voxel value for MD, while only 1% of abnormal CVR and CBF voxels show a concomitant abnormal FA value. These data indicate that DAI and DVI represent two distinct TBI endophenotypes that are spatially independent.
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Affiliation(s)
- Margalit Haber
- Department of Neurology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA
| | - Franck Amyot
- National Intrepid Center of Excellence, Walter Reed National Military Medical Center, Bethesda, MD, USA
| | - Cillian E Lynch
- Department of Neurology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA
| | - Danielle K Sandsmark
- Department of Neurology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA
| | - Kimbra Kenney
- National Intrepid Center of Excellence, Walter Reed National Military Medical Center, Bethesda, MD, USA
- Department of Neurology, Uniformed Services University of the Health Sciences, Bethesda, MD, USA
| | - John K Werner
- Department of Neurology, Uniformed Services University of the Health Sciences, Bethesda, MD, USA
| | - Carol Moore
- Department of Neurology, Uniformed Services University of the Health Sciences, Bethesda, MD, USA
| | - Kelley Flesher
- Department of Neurology, Uniformed Services University of the Health Sciences, Bethesda, MD, USA
| | - Sarah Woodson
- Department of Neurology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA
| | - Erika Silverman
- Department of Neurology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA
| | - Yiyu Chou
- Center for Neuroscience and Regenerative Medicine, Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, USA
| | - Dzung Pham
- Center for Neuroscience and Regenerative Medicine, Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, USA
| | - Ramon Diaz-Arrastia
- Department of Neurology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA
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7
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Troy AM, Cheng HM. Human microvascular reactivity: a review of vasomodulating stimuli and non-invasive imaging assessment. Physiol Meas 2021; 42. [PMID: 34325417 DOI: 10.1088/1361-6579/ac18fd] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 07/29/2021] [Indexed: 11/11/2022]
Abstract
The microvasculature serves an imperative function in regulating perfusion and nutrient exchange throughout the body, adaptively altering blood flow to preserve hemodynamic and metabolic homeostasis. Its normal functioning is vital to tissue health, whereas its dysfunction is present in many chronic conditions, including diabetes, heart disease, and cognitive decline. As microvascular dysfunction often appears early in disease progression, its detection can offer early diagnostic information. To detect microvascular dysfunction, one uses imaging to probe the microvasculature's ability to react to a stimulus, also known as microvascular reactivity (MVR). An assessment of MVR requires an integrated understanding of vascular physiology, techniques for stimulating reactivity, and available imaging methods to capture the dynamic response. Practical considerations, including compatibility between the selected stimulus and imaging approach, likewise require attention. In this review, we provide a comprehensive foundation necessary for informed imaging of MVR, with a particular focus on the challenging endeavor of assessing microvascular function in deep tissues.
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Affiliation(s)
- Aaron M Troy
- Institute of Biomedical Engineering, University of Toronto, Toronto, CANADA
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8
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Zimmerman B, Rypma B, Gratton G, Fabiani M. Age-related changes in cerebrovascular health and their effects on neural function and cognition: A comprehensive review. Psychophysiology 2021; 58:e13796. [PMID: 33728712 PMCID: PMC8244108 DOI: 10.1111/psyp.13796] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 01/11/2021] [Accepted: 02/08/2021] [Indexed: 12/11/2022]
Abstract
The process of aging includes changes in cellular biology that affect local interactions between cells and their environments and eventually propagate to systemic levels. In the brain, where neurons critically depend on an efficient and dynamic supply of oxygen and glucose, age-related changes in the complex interaction between the brain parenchyma and the cerebrovasculature have effects on health and functioning that negatively impact cognition and play a role in pathology. Thus, cerebrovascular health is considered one of the main mechanisms by which a healthy lifestyle, such as habitual cardiorespiratory exercise and a healthful diet, could lead to improved cognitive outcomes with aging. This review aims at detailing how the physiology of the cerebral vascular system changes with age and how these changes lead to differential trajectories of cognitive maintenance or decline. This provides a framework for generating specific mechanistic hypotheses about the efficacy of proposed interventions and lifestyle covariates that contribute to enhanced cognitive well-being. Finally, we discuss the methodological implications of age-related changes in the cerebral vasculature for human cognitive neuroscience research and propose directions for future experiments aimed at investigating age-related changes in the relationship between physiology and cognitive mechanisms.
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Affiliation(s)
- Benjamin Zimmerman
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Bart Rypma
- School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX, USA
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Gabriele Gratton
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Department of Psychology, University of Illinois at Urbana-Champaign, Champaign, IL, USA
- Neuroscience Program, University of Illinois at Urbana-Champaign, Champaign, IL, USA
| | - Monica Fabiani
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Department of Psychology, University of Illinois at Urbana-Champaign, Champaign, IL, USA
- Neuroscience Program, University of Illinois at Urbana-Champaign, Champaign, IL, USA
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9
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Amyot F, Lynch CE, Ollinger J, Werner JK, Silverman E, Moore C, Davis C, Turtzo LC, Diaz-Arrastia R, Kenney K. Cerebrovascular Reactivity Measures Are Associated With Post-traumatic Headache Severity in Chronic TBI; A Retrospective Analysis. Front Physiol 2021; 12:649901. [PMID: 34054569 PMCID: PMC8155500 DOI: 10.3389/fphys.2021.649901] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 03/17/2021] [Indexed: 01/03/2023] Open
Abstract
OBJECTIVE To characterize the relationship between persistent post-traumatic headache (pPTH) and traumatic cerebrovascular injury (TCVI) in chronic traumatic brain injury (TBI). Cerebrovascular reactivity (CVR), a measure of the cerebral microvasculature and endothelial cell function, is altered both in individuals with chronic TBI and migraine headache disorder (Amyot et al., 2017; Lee et al., 2019b). The pathophysiologies of pPTH and migraine are believed to be associated with chronic microvascular dysfunction. We therefore hypothesize that TCVI may contribute to the underlying migraine-like mechanism(s) of pPTH. MATERIALS AND METHODS 22 moderate/severe TBI participants in the chronic stage (>6 months) underwent anatomic and functional magnetic resonance imaging (fMRI) scanning with hypercapnia gas challenge to measure CVR as well as the change in CVR (ΔCVR) after single-dose treatment of a specific phosphodiesterase-5 (PDE-5) inhibitor, sildenafil, which potentiates vasodilation in response to hypercapnia in impaired endothelium, as part of a Phase2a RCT of sildenafil in chronic TBI (NCT01762475). CVR and ΔCVR measures of each participant were compared with the individual's pPTH severity measured by the headache impact test-6 (HIT-6) survey. RESULTS There was a moderate correlation between HIT-6 and both CVR and ΔCVR scores [Spearman's correlation = -0.50 (p = 0.018) and = 0.46 (p = 0.03), respectively], indicating that a higher headache burden is associated with decreased endothelial function in our chronic TBI population. CONCLUSION There is a correlation between PTH and CVR in chronic moderate-severe TBI. This relationship suggests that chronic TCVI may underlie the pathobiology of pPTH. Further, our results suggest that novel treatment strategies that target endothelial function and vascular health may be beneficial in refractory pPTH.
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Affiliation(s)
- Franck Amyot
- National Intrepid Center of Excellence, Walter Reed National Military Medical Center, Bethesda, MD, United States
| | - Cillian E. Lynch
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - John Ollinger
- National Intrepid Center of Excellence, Walter Reed National Military Medical Center, Bethesda, MD, United States
| | - J. Kent Werner
- Department of Neurology, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| | - E. Silverman
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Carol Moore
- Department of Neurology, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| | - Cora Davis
- National Intrepid Center of Excellence, Walter Reed National Military Medical Center, Bethesda, MD, United States
| | - L. Christine Turtzo
- National Institutes of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
| | - Ramon Diaz-Arrastia
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Kimbra Kenney
- National Intrepid Center of Excellence, Walter Reed National Military Medical Center, Bethesda, MD, United States
- Department of Neurology, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
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10
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Pelizzari L, Laganà MM, Baglio F, Bergsland N, Cecconi P, Viotti S, Pugnetti L, Nemni R, Baselli G, Clerici M, Mendozzi L. Cerebrovascular reactivity and its correlation with age in patients with multiple sclerosis. Brain Imaging Behav 2021; 14:1889-1898. [PMID: 31175576 DOI: 10.1007/s11682-019-00132-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
We assessed cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) within gray matter (GM), normal appearing white matter (NAWM) and white matter (WM) lesions in a group of multiple sclerosis (MS) patients. Furthermore, correlations between CBF, CVR and age were investigated. 31 MS patients and 25 healthy controls (HC) were examined on a 1.5 T MRI scanner, using pseudo-continuous arterial spin labeling MRI. MS vs HC CBF and CVR differences were assessed in GM regions of interest (i.e. resting state networks and vascular territories), and within WM. Correlations between CBF/CVR and age were then computed for MS and HC groups. Whereas no significant CBF and CVR differences were observed between MS and HC in any of the considered brain areas, significantly lower CBF was found in WM lesions with respect to NAWM (p < 0.001) in MS patients. Furthermore, CVR was significantly correlated with age in HC, but not in MS patients. The relatively low-grade of inflammation of our MS cohort may be associated with the observed lack of significant CVR differences between MS patients and HC. The loss of correlation between CVR and age in the MS group suggests that CVR may be influenced by MS-related factors.
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Affiliation(s)
- Laura Pelizzari
- IRCCS, Fondazione Don Carlo Gnocchi ONLUS, MRI Laboratory, Via Alfonso Capecelatro, 66, Milan, Italy
| | - Maria M Laganà
- IRCCS, Fondazione Don Carlo Gnocchi ONLUS, MRI Laboratory, Via Alfonso Capecelatro, 66, Milan, Italy.
| | - Francesca Baglio
- IRCCS, Fondazione Don Carlo Gnocchi ONLUS, MRI Laboratory, Via Alfonso Capecelatro, 66, Milan, Italy
| | - Niels Bergsland
- IRCCS, Fondazione Don Carlo Gnocchi ONLUS, MRI Laboratory, Via Alfonso Capecelatro, 66, Milan, Italy.,Buffalo Neuroimaging Analysis Center, Department of Neurology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, USA
| | - Pietro Cecconi
- IRCCS, Fondazione Don Carlo Gnocchi ONLUS, MRI Laboratory, Via Alfonso Capecelatro, 66, Milan, Italy
| | - Stefano Viotti
- IRCCS, Fondazione Don Carlo Gnocchi ONLUS, MRI Laboratory, Via Alfonso Capecelatro, 66, Milan, Italy
| | - Luigi Pugnetti
- IRCCS, Fondazione Don Carlo Gnocchi ONLUS, MRI Laboratory, Via Alfonso Capecelatro, 66, Milan, Italy
| | - Raffaello Nemni
- IRCCS, Fondazione Don Carlo Gnocchi ONLUS, MRI Laboratory, Via Alfonso Capecelatro, 66, Milan, Italy.,Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Milan, Italy
| | - Giuseppe Baselli
- Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milan, Italy
| | - Mario Clerici
- IRCCS, Fondazione Don Carlo Gnocchi ONLUS, MRI Laboratory, Via Alfonso Capecelatro, 66, Milan, Italy.,Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Milan, Italy
| | - Laura Mendozzi
- IRCCS, Fondazione Don Carlo Gnocchi ONLUS, MRI Laboratory, Via Alfonso Capecelatro, 66, Milan, Italy
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11
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Sleight E, Stringer MS, Marshall I, Wardlaw JM, Thrippleton MJ. Cerebrovascular Reactivity Measurement Using Magnetic Resonance Imaging: A Systematic Review. Front Physiol 2021; 12:643468. [PMID: 33716793 PMCID: PMC7947694 DOI: 10.3389/fphys.2021.643468] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 02/01/2021] [Indexed: 12/27/2022] Open
Abstract
Cerebrovascular reactivity (CVR) magnetic resonance imaging (MRI) probes cerebral haemodynamic changes in response to a vasodilatory stimulus. CVR closely relates to the health of the vasculature and is therefore a key parameter for studying cerebrovascular diseases such as stroke, small vessel disease and dementias. MRI allows in vivo measurement of CVR but several different methods have been presented in the literature, differing in pulse sequence, hardware requirements, stimulus and image processing technique. We systematically reviewed publications measuring CVR using MRI up to June 2020, identifying 235 relevant papers. We summarised the acquisition methods, experimental parameters, hardware and CVR quantification approaches used, clinical populations investigated, and corresponding summary CVR measures. CVR was investigated in many pathologies such as steno-occlusive diseases, dementia and small vessel disease and is generally lower in patients than in healthy controls. Blood oxygen level dependent (BOLD) acquisitions with fixed inspired CO2 gas or end-tidal CO2 forcing stimulus are the most commonly used methods. General linear modelling of the MRI signal with end-tidal CO2 as the regressor is the most frequently used method to compute CVR. Our survey of CVR measurement approaches and applications will help researchers to identify good practice and provide objective information to inform the development of future consensus recommendations.
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Affiliation(s)
- Emilie Sleight
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom,UK Dementia Research Institute, Edinburgh, United Kingdom
| | - Michael S. Stringer
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom,UK Dementia Research Institute, Edinburgh, United Kingdom,*Correspondence: Michael S. Stringer
| | - Ian Marshall
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom,UK Dementia Research Institute, Edinburgh, United Kingdom
| | - Joanna M. Wardlaw
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom,UK Dementia Research Institute, Edinburgh, United Kingdom
| | - Michael J. Thrippleton
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom,UK Dementia Research Institute, Edinburgh, United Kingdom
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12
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Tsvetanov KA, Henson RNA, Rowe JB. Separating vascular and neuronal effects of age on fMRI BOLD signals. Philos Trans R Soc Lond B Biol Sci 2021; 376:20190631. [PMID: 33190597 PMCID: PMC7741031 DOI: 10.1098/rstb.2019.0631] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/19/2020] [Indexed: 12/14/2022] Open
Abstract
Accurate identification of brain function is necessary to understand the neurobiology of cognitive ageing, and thereby promote well-being across the lifespan. A common tool used to investigate neurocognitive ageing is functional magnetic resonance imaging (fMRI). However, although fMRI data are often interpreted in terms of neuronal activity, the blood oxygenation level-dependent (BOLD) signal measured by fMRI includes contributions of both vascular and neuronal factors, which change differentially with age. While some studies investigate vascular ageing factors, the results of these studies are not well known within the field of neurocognitive ageing and therefore vascular confounds in neurocognitive fMRI studies are common. Despite over 10 000 BOLD-fMRI papers on ageing, fewer than 20 have applied techniques to correct for vascular effects. However, neurovascular ageing is not only a confound in fMRI, but an important feature in its own right, to be assessed alongside measures of neuronal ageing. We review current approaches to dissociate neuronal and vascular components of BOLD-fMRI of regional activity and functional connectivity. We highlight emerging evidence that vascular mechanisms in the brain do not simply control blood flow to support the metabolic needs of neurons, but form complex neurovascular interactions that influence neuronal function in health and disease. 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)
- Kamen A. Tsvetanov
- Department of Clinical Neurosciences, University of Cambridge, Cambridge CB2 0SZ, UK
- Department of Psychology, University of Cambridge, Cambridge CB2 3EB, UK
| | - Richard N. A. Henson
- Department of Psychiatry, University of Cambridge, Cambridge CB2 0SP, UK
- Medical Research Council Cognition and Brain Sciences Unit, University of Cambridge, Cambridge CB2 7EF, UK
| | - James B. Rowe
- Department of Clinical Neurosciences, University of Cambridge, Cambridge CB2 0SZ, UK
- Medical Research Council Cognition and Brain Sciences Unit, University of Cambridge, Cambridge CB2 7EF, UK
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13
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Dodd AB, Lu H, Wertz CJ, Ling JM, Shaff NA, Wasserott BC, Meier TB, Park G, Oglesbee SJ, Phillips JP, Campbell RA, Liu P, Mayer AR. Persistent alterations in cerebrovascular reactivity in response to hypercapnia following pediatric mild traumatic brain injury. J Cereb Blood Flow Metab 2020; 40:2491-2504. [PMID: 31903838 PMCID: PMC7820694 DOI: 10.1177/0271678x19896883] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 10/15/2019] [Accepted: 11/21/2019] [Indexed: 12/31/2022]
Abstract
Much attention has been paid to the effects of mild traumatic brain injury (mTBI) on cerebrovascular reactivity in adult populations, yet it remains understudied in pediatric injury. In this study, 30 adolescents (12-18 years old) with pediatric mTBI (pmTBI) and 35 age- and sex-matched healthy controls (HC) underwent clinical and neuroimaging assessments during sub-acute (6.9 ± 2.2 days) and early chronic (120.4 ± 11.7 days) phases of injury. Relative to controls, pmTBI reported greater initial post-concussion symptoms, headache, pain, and anxiety, resolving by four months post-injury. Patients reported increased sleep issues and exhibited deficits in processing speed and attention across both visits. In grey-white matter interface areas throughout the brain, pmTBI displayed increased maximal fit/amplitude of a time-shifted end-tidal CO2 regressor to blood oxygen-level dependent response relative to HC, as well as increased latency to maximal fit. The alterations persisted through the early chronic phase of injury, with maximal fit being associated with complaints of ongoing sleep disturbances during post hoc analyses but not cognitive measures of processing speed or attention. Collectively, these findings suggest that deficits in the speed and degree of cerebrovascular reactivity may persist longer than current conceptualizations about clinical recovery within 30 days.
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Affiliation(s)
- Andrew B Dodd
- The Mind Research Network/Lovelace Biomedical and Environmental Research Institute, Albuquerque, NM, USA
| | - Hanzhang Lu
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Christopher J Wertz
- The Mind Research Network/Lovelace Biomedical and Environmental Research Institute, Albuquerque, NM, USA
| | - Josef M Ling
- The Mind Research Network/Lovelace Biomedical and Environmental Research Institute, Albuquerque, NM, USA
| | - Nicholas A Shaff
- The Mind Research Network/Lovelace Biomedical and Environmental Research Institute, Albuquerque, NM, USA
| | - Benjamin C Wasserott
- The Mind Research Network/Lovelace Biomedical and Environmental Research Institute, Albuquerque, NM, USA
| | - Timothy B Meier
- Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, WI, USA
- Departments of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA
- Department of Biomedical Engineering, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Grace Park
- Department of Pediatric Emergency Medicine, University of New Mexico, Albuquerque, NM, USA
| | - Scott J Oglesbee
- Department of Pediatric Emergency Medicine, University of New Mexico, Albuquerque, NM, USA
| | - John P Phillips
- The Mind Research Network/Lovelace Biomedical and Environmental Research Institute, Albuquerque, NM, USA
- Department of Neurology, University of New Mexico, Albuquerque, NM, USA
| | - Richard A Campbell
- Department of Psychiatry, University of New Mexico, Albuquerque, NM, USA
| | - Peiying Liu
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Andrew R Mayer
- The Mind Research Network/Lovelace Biomedical and Environmental Research Institute, Albuquerque, NM, USA
- Department of Neurology, University of New Mexico, Albuquerque, NM, USA
- Department of Psychiatry, University of New Mexico, Albuquerque, NM, USA
- Department of Psychology, University of New Mexico, Albuquerque, NM, USA
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14
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Ashimatey BS, D'Orazio LM, Ma SJ, Jann K, Jiang X, Lu H, Wang DJ, Ringman JM, Kashani AH. Lower retinal capillary density in minimal cognitive impairment among older Latinx adults. ALZHEIMER'S & DEMENTIA (AMSTERDAM, NETHERLANDS) 2020; 12:e12071. [PMID: 32875053 PMCID: PMC7447879 DOI: 10.1002/dad2.12071] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 06/17/2020] [Accepted: 06/23/2020] [Indexed: 01/21/2023]
Abstract
INTRODUCTION We investigated the hypothesis that retinal capillary perfusion is a biomarker of early cognitive decline and cerebrovascular perfusion associated with small vessel disease in a pilot data set of Latinx adults at high risk for vascular cognitive impairment and dementia. METHODS High-resolution optical coherence tomography angiography (OCTA) images were acquired from dilated eyes of Latinx subjects using a 3 × 3 mm2 scan pattern from a commercially available device. A previously validated method was used to quantify the density of perfused retinal capillaries as the retinal vessel skeleton density (VSD). The association of VSD with Clinical Dementia Rating Sum of Boxes, total Montreal Cognitive Assessment (MoCA) score, and individual MoCA test elements were analyzed using multivariate statistics that adjusted for confounders. VSD was also compared with magnetic resonance imaging (MRI) measures of cerebrovascular reactivity (CVR) and perfusion in the middle cerebral artery perforator (MCA-Perf) territory. RESULTS The mean (± SD) age of the subjects was 68 (± 6) years. For every 0.01-unit lower VSD, the risk of having a CDR-SOB >0 was 20% higher (95%CI = 5%-90%; P = .031). Similarly, a lower VSD was associated with lower total MoCA score (r = 0.3; P = .038). The Visuospatial/Executive domain of the MoCA assessment showed the strongest association with VSD ( β = 0.02; P = .022). Lower retinal VSD was associated with worse MRI measure of CVR (r = 0.7, P = .04) and less perfusion in the MCA-Perf territory (r = 0.45, P = .02). DISCUSSION Impaired retinal capillary perfusion is associated with cognitive impairment and abnormalities in cerebrovascular perfusion and function. OCTA-based retinal capillary assessment holds promise for identifying and quantifying retinal correlates of neurovascular abnormalities associated with vascular cognitive impairment.
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Affiliation(s)
- Bright S. Ashimatey
- Department of Ophthalmology, USC Roski Eye InstituteKeck School of Medicine of the University of Southern CaliforniaLos AngelesCaliforniaUSA
| | - Lina M. D'Orazio
- Department of NeurologyKeck School of MedicineUniversity of Southern CaliforniaLos AngelesCaliforniaUSA
| | - Samantha J. Ma
- Laboratory of FMRI Technology (LOFT), Mark & Mary Stevens Neuroimaging and Informatics InstituteKeck School of MedicineUniversity of Southern CaliforniaLos AngelesCaliforniaUSA
| | - Kay Jann
- Laboratory of FMRI Technology (LOFT), Mark & Mary Stevens Neuroimaging and Informatics InstituteKeck School of MedicineUniversity of Southern CaliforniaLos AngelesCaliforniaUSA
| | - Xuejuan Jiang
- Department of Ophthalmology, USC Roski Eye InstituteKeck School of Medicine of the University of Southern CaliforniaLos AngelesCaliforniaUSA
| | - Hanzhang Lu
- Department of RadiologyJohns Hopkins University School of MedicineBaltimoreMarylandUSA
| | - Danny J.J. Wang
- Department of NeurologyKeck School of MedicineUniversity of Southern CaliforniaLos AngelesCaliforniaUSA
- Laboratory of FMRI Technology (LOFT), Mark & Mary Stevens Neuroimaging and Informatics InstituteKeck School of MedicineUniversity of Southern CaliforniaLos AngelesCaliforniaUSA
| | - John M. Ringman
- Department of NeurologyKeck School of MedicineUniversity of Southern CaliforniaLos AngelesCaliforniaUSA
| | - Amir H. Kashani
- Department of Ophthalmology, USC Roski Eye InstituteKeck School of Medicine of the University of Southern CaliforniaLos AngelesCaliforniaUSA
- USC Ginsburg Institute for Biomedical TherapeuticsLos AngelesCaliforniaUSA
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15
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Taneja K, Liu P, Xu C, Turner M, Zhao Y, Abdelkarim D, Thomas BP, Rypma B, Lu H. Quantitative Cerebrovascular Reactivity in Normal Aging: Comparison Between Phase-Contrast and Arterial Spin Labeling MRI. Front Neurol 2020; 11:758. [PMID: 32849217 PMCID: PMC7411174 DOI: 10.3389/fneur.2020.00758] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 06/19/2020] [Indexed: 12/20/2022] Open
Abstract
Purpose: Cerebrovascular reactivity (CVR) is an index of the dilatory function of cerebral blood vessels and has shown great promise in the diagnosis of risk factors in cerebrovascular disease. Aging is one such risk factor; thus, it is important to characterize age-related differences in CVR. CVR can be measured by BOLD MRI but few studies have measured quantitative cerebral blood flow (CBF)-based CVR in the context of aging. This study aims to determine the age effect on CVR using two quantitative CBF techniques, phase-contrast (PC), and arterial spin labeling (ASL) MRI. Methods: In 49 participants (32 younger and 17 older), CVR was measured with PC, ASL, and BOLD MRI. These CVR methods were compared across young and older groups to determine their dependence on age. PC and ASL CVR were also studied for inter-correlation and mean differences. Gray and white matter CVR values were also studied. Results: PC CVR was higher in younger participants than older participants (by 17%, p = 0.046). However, there were no age differences in ASL or BOLD CVR. ASL CVR was significantly correlated with PC CVR (p = 0.042) and BOLD CVR (p = 0.016), but its values were underestimated compared to PC CVR (p = 0.045). ASL CVR map revealed no difference between gray matter and white matter tissue types, whereas gray matter was significantly higher than white matter in the BOLD CVR map. Conclusion: This study compared two quantitative CVR techniques in the context of brain aging and revealed that PC CVR is a more sensitive method for detection of age differences, despite the absence of spatial information. The ASL method showed a significant correlation with PC and BOLD, but it tends to underestimate CVR due to confounding factors associated with this technique. Importantly, our data suggest that there is not a difference in CBF-based CVR between the gray and white matter, in contrast to previous observation using BOLD MRI.
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Affiliation(s)
- Kamil Taneja
- The Russel H. Morgan Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Peiying Liu
- The Russel H. Morgan Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Cuimei Xu
- The Russel H. Morgan Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Monroe Turner
- School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX, United States
| | - Yuguang Zhao
- School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX, United States
| | - Dema Abdelkarim
- School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX, United States
| | - Binu P Thomas
- Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Bart Rypma
- School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX, United States.,Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Hanzhang Lu
- The Russel H. Morgan Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, United States.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States.,Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, United States
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16
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Sur S, Lin Z, Li Y, Yasar S, Rosenberg P, Moghekar A, Hou X, Kalyani R, Hazel K, Pottanat G, Xu C, van Zijl P, Pillai J, Liu P, Albert M, Lu H. Association of cerebrovascular reactivity and Alzheimer pathologic markers with cognitive performance. Neurology 2020; 95:e962-e972. [PMID: 32661101 DOI: 10.1212/wnl.0000000000010133] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Accepted: 03/17/2020] [Indexed: 01/14/2023] Open
Abstract
OBJECTIVE To determine whether MRI-based cerebrovascular reactivity (CVR) can predict cognitive performance independently of Alzheimer pathologic markers, we studied the relationship between cognition, CVR, and CSF-derived β-amyloid42 (Aβ42) and tau in a group of elderly individuals with mixed Alzheimer and vascular cognitive impairment and dementia. METHODS This was a cross-sectional study of 72 participants 69 ± 8 years of age consisting of individuals with normal cognition (n = 28) and cognitive impairment (n = 44) (including 36 with mild cognitive impairment [MCI] and 8 with mild dementia). CVR was measured with hypercapnia-MRI. Whole-brain CVR (percent blood oxygen level-dependent per 1 mm Hg Etco2) was used to estimate vasodilatory capacity. Montreal Cognitive Assessment (MoCA) scores, cognitive domains scores, and a global composite cognitive score were obtained. AD biomarkers included CSF assays of Aβ42 and tau. RESULTS Whole-brain CVR was lower in the impaired (mean ± SE, 0.132 ± 0.006%/mm Hg) compared to the normal (0.151 ± 0.007%/mm Hg) group (β = -0.02%/mm Hg; 95% confidence interval [CI] -0.038 to -0.001). After adjustment for CSF Aβ42 and tau, higher whole-brain CVR was associated with better performance on the MoCA (β = 29.64, 95% CI 9.94-49.34) and with a global composite cognitive score (β = 4.32, 95% CI 0.05-8.58). When the CVR marker was compared with the Fazekas score based on white matter hyperintensities and vascular risk-score in a single regression model predicting the MoCA score, only CVR revealed a significant effect (β = 28.09, 95% CI 6.14-50.04), while the other 2 measures were not significant. CONCLUSIONS CVR was significantly associated with cognitive performance independently of AD pathology. Whole-brain CVR may be a useful biomarker for evaluating cognitive impairment related to vascular disease in older individuals. CLASSIFICATION OF EVIDENCE This study provides Class II evidence that CVR was significantly associated with cognitive performance independent of AD pathology.
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Affiliation(s)
- Sandeepa Sur
- From the Departments of Radiology (S.S., Z.L., Y.L., X.H., K.H., G.P., C.X., P.v.Z., J.P., P.L., H.L.), Biomedical Engineering (Z.L., X.H., H.L.), Medicine (S.Y., R.K.), Psychiatry and Behavioral Sciences (P.R.), Neurology (A.M., M.A.), and Neurosurgery (J.P.), Johns Hopkins University, School of Medicine; and F.M. Kirby Research Center (P.v.Z., H.L.), Kennedy Krieger Institute, Baltimore, MD
| | - Zixuan Lin
- From the Departments of Radiology (S.S., Z.L., Y.L., X.H., K.H., G.P., C.X., P.v.Z., J.P., P.L., H.L.), Biomedical Engineering (Z.L., X.H., H.L.), Medicine (S.Y., R.K.), Psychiatry and Behavioral Sciences (P.R.), Neurology (A.M., M.A.), and Neurosurgery (J.P.), Johns Hopkins University, School of Medicine; and F.M. Kirby Research Center (P.v.Z., H.L.), Kennedy Krieger Institute, Baltimore, MD
| | - Yang Li
- From the Departments of Radiology (S.S., Z.L., Y.L., X.H., K.H., G.P., C.X., P.v.Z., J.P., P.L., H.L.), Biomedical Engineering (Z.L., X.H., H.L.), Medicine (S.Y., R.K.), Psychiatry and Behavioral Sciences (P.R.), Neurology (A.M., M.A.), and Neurosurgery (J.P.), Johns Hopkins University, School of Medicine; and F.M. Kirby Research Center (P.v.Z., H.L.), Kennedy Krieger Institute, Baltimore, MD
| | - Sevil Yasar
- From the Departments of Radiology (S.S., Z.L., Y.L., X.H., K.H., G.P., C.X., P.v.Z., J.P., P.L., H.L.), Biomedical Engineering (Z.L., X.H., H.L.), Medicine (S.Y., R.K.), Psychiatry and Behavioral Sciences (P.R.), Neurology (A.M., M.A.), and Neurosurgery (J.P.), Johns Hopkins University, School of Medicine; and F.M. Kirby Research Center (P.v.Z., H.L.), Kennedy Krieger Institute, Baltimore, MD
| | - Paul Rosenberg
- From the Departments of Radiology (S.S., Z.L., Y.L., X.H., K.H., G.P., C.X., P.v.Z., J.P., P.L., H.L.), Biomedical Engineering (Z.L., X.H., H.L.), Medicine (S.Y., R.K.), Psychiatry and Behavioral Sciences (P.R.), Neurology (A.M., M.A.), and Neurosurgery (J.P.), Johns Hopkins University, School of Medicine; and F.M. Kirby Research Center (P.v.Z., H.L.), Kennedy Krieger Institute, Baltimore, MD
| | - Abhay Moghekar
- From the Departments of Radiology (S.S., Z.L., Y.L., X.H., K.H., G.P., C.X., P.v.Z., J.P., P.L., H.L.), Biomedical Engineering (Z.L., X.H., H.L.), Medicine (S.Y., R.K.), Psychiatry and Behavioral Sciences (P.R.), Neurology (A.M., M.A.), and Neurosurgery (J.P.), Johns Hopkins University, School of Medicine; and F.M. Kirby Research Center (P.v.Z., H.L.), Kennedy Krieger Institute, Baltimore, MD
| | - Xirui Hou
- From the Departments of Radiology (S.S., Z.L., Y.L., X.H., K.H., G.P., C.X., P.v.Z., J.P., P.L., H.L.), Biomedical Engineering (Z.L., X.H., H.L.), Medicine (S.Y., R.K.), Psychiatry and Behavioral Sciences (P.R.), Neurology (A.M., M.A.), and Neurosurgery (J.P.), Johns Hopkins University, School of Medicine; and F.M. Kirby Research Center (P.v.Z., H.L.), Kennedy Krieger Institute, Baltimore, MD
| | - Rita Kalyani
- From the Departments of Radiology (S.S., Z.L., Y.L., X.H., K.H., G.P., C.X., P.v.Z., J.P., P.L., H.L.), Biomedical Engineering (Z.L., X.H., H.L.), Medicine (S.Y., R.K.), Psychiatry and Behavioral Sciences (P.R.), Neurology (A.M., M.A.), and Neurosurgery (J.P.), Johns Hopkins University, School of Medicine; and F.M. Kirby Research Center (P.v.Z., H.L.), Kennedy Krieger Institute, Baltimore, MD
| | - Kaisha Hazel
- From the Departments of Radiology (S.S., Z.L., Y.L., X.H., K.H., G.P., C.X., P.v.Z., J.P., P.L., H.L.), Biomedical Engineering (Z.L., X.H., H.L.), Medicine (S.Y., R.K.), Psychiatry and Behavioral Sciences (P.R.), Neurology (A.M., M.A.), and Neurosurgery (J.P.), Johns Hopkins University, School of Medicine; and F.M. Kirby Research Center (P.v.Z., H.L.), Kennedy Krieger Institute, Baltimore, MD
| | - George Pottanat
- From the Departments of Radiology (S.S., Z.L., Y.L., X.H., K.H., G.P., C.X., P.v.Z., J.P., P.L., H.L.), Biomedical Engineering (Z.L., X.H., H.L.), Medicine (S.Y., R.K.), Psychiatry and Behavioral Sciences (P.R.), Neurology (A.M., M.A.), and Neurosurgery (J.P.), Johns Hopkins University, School of Medicine; and F.M. Kirby Research Center (P.v.Z., H.L.), Kennedy Krieger Institute, Baltimore, MD
| | - Cuimei Xu
- From the Departments of Radiology (S.S., Z.L., Y.L., X.H., K.H., G.P., C.X., P.v.Z., J.P., P.L., H.L.), Biomedical Engineering (Z.L., X.H., H.L.), Medicine (S.Y., R.K.), Psychiatry and Behavioral Sciences (P.R.), Neurology (A.M., M.A.), and Neurosurgery (J.P.), Johns Hopkins University, School of Medicine; and F.M. Kirby Research Center (P.v.Z., H.L.), Kennedy Krieger Institute, Baltimore, MD
| | - Peter van Zijl
- From the Departments of Radiology (S.S., Z.L., Y.L., X.H., K.H., G.P., C.X., P.v.Z., J.P., P.L., H.L.), Biomedical Engineering (Z.L., X.H., H.L.), Medicine (S.Y., R.K.), Psychiatry and Behavioral Sciences (P.R.), Neurology (A.M., M.A.), and Neurosurgery (J.P.), Johns Hopkins University, School of Medicine; and F.M. Kirby Research Center (P.v.Z., H.L.), Kennedy Krieger Institute, Baltimore, MD
| | - Jay Pillai
- From the Departments of Radiology (S.S., Z.L., Y.L., X.H., K.H., G.P., C.X., P.v.Z., J.P., P.L., H.L.), Biomedical Engineering (Z.L., X.H., H.L.), Medicine (S.Y., R.K.), Psychiatry and Behavioral Sciences (P.R.), Neurology (A.M., M.A.), and Neurosurgery (J.P.), Johns Hopkins University, School of Medicine; and F.M. Kirby Research Center (P.v.Z., H.L.), Kennedy Krieger Institute, Baltimore, MD
| | - Peiying Liu
- From the Departments of Radiology (S.S., Z.L., Y.L., X.H., K.H., G.P., C.X., P.v.Z., J.P., P.L., H.L.), Biomedical Engineering (Z.L., X.H., H.L.), Medicine (S.Y., R.K.), Psychiatry and Behavioral Sciences (P.R.), Neurology (A.M., M.A.), and Neurosurgery (J.P.), Johns Hopkins University, School of Medicine; and F.M. Kirby Research Center (P.v.Z., H.L.), Kennedy Krieger Institute, Baltimore, MD
| | - Marilyn Albert
- From the Departments of Radiology (S.S., Z.L., Y.L., X.H., K.H., G.P., C.X., P.v.Z., J.P., P.L., H.L.), Biomedical Engineering (Z.L., X.H., H.L.), Medicine (S.Y., R.K.), Psychiatry and Behavioral Sciences (P.R.), Neurology (A.M., M.A.), and Neurosurgery (J.P.), Johns Hopkins University, School of Medicine; and F.M. Kirby Research Center (P.v.Z., H.L.), Kennedy Krieger Institute, Baltimore, MD
| | - Hanzhang Lu
- From the Departments of Radiology (S.S., Z.L., Y.L., X.H., K.H., G.P., C.X., P.v.Z., J.P., P.L., H.L.), Biomedical Engineering (Z.L., X.H., H.L.), Medicine (S.Y., R.K.), Psychiatry and Behavioral Sciences (P.R.), Neurology (A.M., M.A.), and Neurosurgery (J.P.), Johns Hopkins University, School of Medicine; and F.M. Kirby Research Center (P.v.Z., H.L.), Kennedy Krieger Institute, Baltimore, MD.
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17
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Lewis N, Lu H, Liu P, Hou X, Damaraju E, Iraji A, Calhoun V. Static and dynamic functional connectivity analysis of cerebrovascular reactivity: An fMRI study. Brain Behav 2020; 10:e01516. [PMID: 32342644 PMCID: PMC7303385 DOI: 10.1002/brb3.1516] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 08/20/2019] [Accepted: 10/03/2019] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Cerebrovascular reactivity (CVR) is an important aspect of brain function, and as such it is important to understand relationship between CVR and functional connectivity. METHODS This research studied the role of CVR, or the brain's ability to react to vasoactive stimuli on brain functional connectivity by scanning subjects with blood-oxygenation-level-dependent (BOLD) functional magnetic resonance imaging (fMRI) while they periodically inhale room air and a CO 2-enriched gas mixture. We developed a new metric to measure the effect of CVR on each intrinsic connectivity network (ICN), which contrasts to voxel-wise CVR. We also studied the changes in whole-brain connectivity patterns using both static functional network connectivity (sFNC) and dynamic FNC (dFNC). RESULTS We found that network connectivity is generally weaker during vascular dilation, which is supported by previous research. The dFNC analysis revealed that participants did not return to the pre-CO 2 inhalation state, suggesting that one-minute periods of room-air inhalation is not enough for the CO 2 effect to fully dissipate. CONCLUSIONS Cerebrovascular reactivity is one tool that the cerebrovascular system uses to ensure the constant, finely-tuned flow of oxygen to function properly. Understanding the relationship between CVR and brain dynamism can provide unique information about cerebrovascular diseases and general brain function. We observed that CVR has a wide, but consistent relationship to connectivity patterns between functional networks.
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Affiliation(s)
- Noah Lewis
- Tri-Institutional Center for Translational Research in Neuroimaging and Data Science, Georgia State University, Georgia institute of Technology, Emory UniversityAtlantaGAUSA
- Department of Computer ScienceUniversity of New MexicoAlbuquerqueNMUSA
| | - Hanzhang Lu
- Johns Hopkins University School of MedicineBaltimoreMDUSA
| | - Peiying Liu
- Johns Hopkins University School of MedicineBaltimoreMDUSA
| | - Xirui Hou
- Johns Hopkins University School of MedicineBaltimoreMDUSA
| | - Eswar Damaraju
- Tri-Institutional Center for Translational Research in Neuroimaging and Data Science, Georgia State University, Georgia institute of Technology, Emory UniversityAtlantaGAUSA
| | - Armin Iraji
- Tri-Institutional Center for Translational Research in Neuroimaging and Data Science, Georgia State University, Georgia institute of Technology, Emory UniversityAtlantaGAUSA
| | - Vince Calhoun
- Tri-Institutional Center for Translational Research in Neuroimaging and Data Science, Georgia State University, Georgia institute of Technology, Emory UniversityAtlantaGAUSA
- Department of Electrical and Computer EngineeringUniversity of New MexicoAlbuquerqueNMUSA
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18
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Liu P, Xu C, Lin Z, Sur S, Li Y, Yasar S, Rosenberg P, Albert M, Lu H. Cerebrovascular reactivity mapping using intermittent breath modulation. Neuroimage 2020; 215:116787. [PMID: 32278094 DOI: 10.1016/j.neuroimage.2020.116787] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 03/24/2020] [Accepted: 03/30/2020] [Indexed: 01/28/2023] Open
Abstract
Cerebrovascular reactivity (CVR), an index of brain vessel's dilatory capacity, is typically measured using hypercapnic gas inhalation or breath-holding as a vasoactive challenge. However, these methods require considerable subject cooperation and could be challenging in clinical studies. More recently, there have been attempts to use resting-state BOLD data to map CVR by utilizing spontaneous changes in breathing pattern. However, in subjects who have small fluctuations in their spontaneous breathing pattern, the CVR results could be noisy and unreliable. In this study, we aim to develop a new method for CVR mapping that does not require gas-inhalation yet provides substantially higher sensitivity than resting-state CVR mapping. This new method is largely based on resting-state scan, but introduces intermittent modulation of breathing pattern in the subject to enhance fluctuations in their end-tidal CO2 (EtCO2) level. Here we examined the comfort level, sensitivity, and accuracy of this method in two studies. First, in 8 healthy young subjects, we developed the intermittent breath-modulation method using two different modulation frequencies, 6 s per breath and 12 s per breath, respectively, and compared the results to three existing CVR methods, specifically hypercapnic gas inhalation, breath-holding, and resting-state. Our results showed that the comfort level of the 6-s breath-modulation method was significantly higher than breath-holding (p = 0.007) and CO2-inhalation (p = 0.015) methods, while not different from the resting-state, i.e. free breathing method (p = 0.52). When comparing the sensitivity of CVR methods, the breath-modulation methods revealed higher Z-statistics compared to the resting-state scan (p < 0.008) and was comparable to breath-holding results. Next, we tested the feasibility of breath-modulation CVR mapping (6 s per breath) in 21 cognitively normal elderly participants and compared quantitative CVR values to that obtained with the CO2-inhalation method. Whole-brain CVR was found to be 0.150 ± 0.055 and 0.154 ± 0.032 %ΔBOLD/mmHg for the breath-modulation and CO2-inhalation method, respectively, with a significant correlation between them (y = 0.97x, p = 0.007). CVR mapping with intermittent breath modulation may be a useful method that combines the advantages of resting-state and CO2-inhalation based approaches.
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Affiliation(s)
- Peiying Liu
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
| | - Cuimei Xu
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Zixuan Lin
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Sandeepa Sur
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Yang Li
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Sevil Yasar
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Paul Rosenberg
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Marilyn Albert
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Hanzhang Lu
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA; F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute, Baltimore, MD, USA
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19
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Kushner-Lenhoff S, Ashimatey BS, Kashani AH. Retinal Vascular Reactivity as Assessed by Optical Coherence Tomography Angiography. J Vis Exp 2020. [PMID: 32281974 DOI: 10.3791/60948] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The vascular supply to the retina has been shown to dynamically adapt through vasoconstriction and vasodilation to accommodate the metabolic demands of the retina. This process, referred to as retinal vascular reactivity (RVR), is mediated by neurovascular coupling, which is impaired very early in retinal vascular diseases such as diabetic retinopathy. Therefore, a clinically feasible method of assessing vascular function may be of significant interest in both research and clinical settings. Recently, in vivo imaging of the retinal vasculature at the capillary level has been made possible by the FDA approval of optical coherence tomography angiography (OCTA), a noninvasive, minimal risk and dyeless angiography method with capillary level resolution. Concurrently, physiological and pathological changes in RVR have been shown by several investigators. The method shown in this manuscript is designed to investigate RVR using OCTA with no need for alterations to the clinical imaging procedures or device. It demonstrates real time imaging of the retina and retinal vasculature during exposure to hypercapnic or hyperoxic conditions. The exam is easily performed with two personnel in under 30 min with minimal subject discomfort or risk. This method is adaptable to other ophthalmic imaging devices and the applications may vary based on the composition of the gas mixture and patient population. A strength of this method is that it allows for an investigation of retinal vascular function at the capillary level in human subjects in vivo. Limitations of this method are largely those of OCTA and other retinal imaging methods including imaging artifacts and a restricted dynamic range. The results obtained from the method are OCT and OCTA images of the retina. These images are amenable to any analysis that is possible on commercially available OCT or OCTA devices. The general method, however, can be adapted to any form of ophthalmic imaging.
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Affiliation(s)
| | | | - Amir H Kashani
- Department of Ophthalmology, USC Roski Eye Institute; USC Ginsberg Institute for Biomedical Therapeutics, Keck School of Medicine of the University of Southern California;
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20
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The association between BOLD-based cerebrovascular reactivity (CVR) and end-tidal CO 2 in healthy subjects. Neuroimage 2019; 207:116365. [PMID: 31734432 PMCID: PMC8080082 DOI: 10.1016/j.neuroimage.2019.116365] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 10/25/2019] [Accepted: 11/13/2019] [Indexed: 01/22/2023] Open
Abstract
Cerebrovascular reactivity (CVR) mapping using CO2-inhalation can provide important insight into vascular health. At present, blood-oxygenation-level-dependent (BOLD) MRI acquisition is the most commonly used CVR method due to its high sensitivity, high spatial resolution, and relatively straightforward processing. However, large variations in CVR across subjects and across different sessions of the same subject are often observed, which can cloud the ability of this promising measure in detecting diseases or monitoring treatment responses. The present work aims to identify the physiological components underlying the observed variability in CVR data. When studying the association between CVR value and the subject’s CO2 levels in a total of N = 253 healthy participants, we found that CVR was lower in individuals with a higher basal end-tidal CO2, EtCO2 (slope = −0.0036 ± 0.0008%/mmHg2, p < 0.001), or with a greater EtCO2 change (ΔEtCO2) with hypercapnic condition (slope = −0.0072 ± 0.0018%/mmHg2, p < 0.001). In a within-subject setting, when studying the CVR difference between two repeated scans (with repositioning) in relation to the corresponding differences in basal EtCO2 and ΔEtCO2 (n = 11), it was found that CVR values were lower if the basal EtCO2 or ΔEtCO2 during that particular scan session was greater. The present work suggests that basal physiological state and the level of hypercapnic stimulus intensity should be considered in application studies of CVR in order to reduce inter-subject and intra-subject variations in the data. Potential approaches to use these findings to reduce noise and augment sensitivity are proposed.
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Amyot F, Kenney K, Spessert E, Moore C, Haber M, Silverman E, Gandjbakhche A, Diaz-Arrastia R. Assessment of cerebrovascular dysfunction after traumatic brain injury with fMRI and fNIRS. Neuroimage Clin 2019; 25:102086. [PMID: 31790877 PMCID: PMC6909332 DOI: 10.1016/j.nicl.2019.102086] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 11/07/2019] [Accepted: 11/09/2019] [Indexed: 11/26/2022]
Abstract
Traumatic cerebral vascular injury (TCVI) is a frequent, but under-recognized, endophenotype of traumatic brain injury (TBI). It likely contributes to functional deficits after TBI and TBI-related chronic disability, and represents an attractive target for targeted therapeutic interventions. The aim of this prospective study is to assess microvascular injury/dysfunction in chronic TBI by measuring cerebral vascular reactivity (CVR) by 2 methods, functional magnetic resonance imaging (fMRI) and functional Near InfraRed Spectroscopy (fNIRS) imaging, as each has attractive features relevant to clinical utility. 42 subjects (27 chronic TBI, 15 age- and gender-matched non-TBI volunteers) were enrolled and underwent outpatient CVR testing by 2 methods, MRI-BOLD and fNIRS, each with hypercapnia challenge, a neuropsychological testing battery, and symptom survey questionnaires. Chronic TBI subjects showed a significant reduction in global CVR compared to HC (p < 0.0001). Mean CVR measures by fMRI were 0.225 ± 0.014 and 0.183 ± 0.026 %BOLD/mmHg for non-TBI and TBI subjects respectively and 12.3 ± 1.8 and 9.2 ± 1.7 mM/mmHg by fNIRS for non-TBI versus TBI subjects respectively. Global CVR measured by fNIRS imaging correlates with results by MRI-BOLD (R = 0.5). Focal CVR deficits seen on CVR maps by fMRI are also observed in the same areas by fNIRS in the frontal regions. Global CVR is significantly lower in chronic TBI patients and is reliably measured by both fMRI and fNIRS, the former with better spatial and the latter with better temporal resolution. Both methods show promise as non-invasive measures of CVR function and microvascular integrity after TBI.
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Affiliation(s)
- Franck Amyot
- Department of Neurology, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA; Center for Neuroscience and Regenerative Medicine, Department of Neurology, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA.
| | - Kimbra Kenney
- Department of Neurology, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA; Center for Neuroscience and Regenerative Medicine, Department of Neurology, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA
| | - Emily Spessert
- Department of Neurology, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA; Center for Neuroscience and Regenerative Medicine, Department of Neurology, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA
| | - Carol Moore
- Department of Neurology, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA; Center for Neuroscience and Regenerative Medicine, Department of Neurology, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA
| | - Margalit Haber
- Department of Neurology, University of Pennsylvania Perelman School of Medicine, Philadelphia
| | - Erika Silverman
- Department of Neurology, University of Pennsylvania Perelman School of Medicine, Philadelphia
| | - Amir Gandjbakhche
- Section on Analytical and Functional Biophotonics, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH), Bethesda, Maryland, USA
| | - Ramon Diaz-Arrastia
- Center for Neuroscience and Regenerative Medicine, Department of Neurology, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA; Department of Neurology, University of Pennsylvania Perelman School of Medicine, Philadelphia
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22
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Ashimatey BS, Green KM, Chu Z, Wang RK, Kashani AH. Impaired Retinal Vascular Reactivity in Diabetic Retinopathy as Assessed by Optical Coherence Tomography Angiography. Invest Ophthalmol Vis Sci 2019; 60:2468-2473. [PMID: 31173077 PMCID: PMC6557617 DOI: 10.1167/iovs.18-26417] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Purpose To assess retinal vascular reactivity in healthy controls and subjects with diabetic retinopathy (DR). Methods A total of 22 healthy control eyes and 16 eyes with DR were enrolled. Images were acquired using a commercially available swept-source optical coherence tomography angiography (SS-OCTA) system. Three conditions were tested for each patient (hyperoxia, hypercapnia, and room-air) by employing a non-rebreathing apparatus that delivered appropriate gas mixtures (100% O2, 5% CO2, room air). Vessel skeleton density (VSD) and vessel diameter index (VDI) were compared between the conditions using mixed-model ANOVA adjusting for age and hypertension. Significant gas or interaction effects were followed by a Bonferroni adjusted pairwise post hoc analysis. Statistical significance was defined at P < 0.05. Results The mixed-model ANOVA of the VSD found a significant intraindividual gas effect (F[2, 70] = 20.3, P < 0.001) and intergroup effect (F[1, 35] = 6.9, P = 0.001), and interaction effects (F[2, 70] = 4.6, P = 0.03). The post hoc pairwise comparison found significant differences among all three gas conditions in the healthy controls. In the subjects with DR, there were significant differences in VSD between hyperoxic and room air, and between hyperoxic and hypercapnic conditions, but not between hypercapnic and room-air conditions. Similar results were found for VDI. Conclusions The retinal capillaries, assessed with SS-OCTA, in subjects with DR preferentially reacted to hyperoxia but not hypercapnia, while the healthy controls reacted to both. The difference in the vascular reactivity may be indicative of the underlying pathophysiology of DR.
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Affiliation(s)
- Bright S. Ashimatey
- Department of Ophthalmology, USC Roski Eye Institute, Keck School of Medicine of the University of Southern California, Los Angeles, California, United States
| | - Kyle M. Green
- Department of Ophthalmology, USC Roski Eye Institute, Keck School of Medicine of the University of Southern California, Los Angeles, California, United States
| | - Zhongdi Chu
- Department of Bioengineering, University of Washington, Seattle, Washington, United States
| | - Ruikang K. Wang
- Department of Bioengineering, University of Washington, Seattle, Washington, United States
,Department of Ophthalmology, University of Washington, Seattle, Washington, United States
| | - Amir H. Kashani
- Department of Ophthalmology, USC Roski Eye Institute, Keck School of Medicine of the University of Southern California, Los Angeles, California, United States
,USC Ginsberg Institute for Biomedical Therapeutics, Los Angeles, California, United States
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23
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Evaluation of cerebrovascular reserve in patients with cerebrovascular diseases using resting-state MRI: A feasibility study. Magn Reson Imaging 2019; 59:46-52. [PMID: 30849484 DOI: 10.1016/j.mri.2019.03.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 03/03/2019] [Accepted: 03/04/2019] [Indexed: 11/22/2022]
Abstract
PURPOSE To demonstrate the feasibility of mapping cerebrovascular reactivity (CVR) using resting-state functional MRI (fMRI) data without gas or other challenges in patients with cerebrovascular diseases and to show that brain regions affected by the diseases have diminished vascular reactivity. MATERIALS AND METHODS Two sub-studies were performed on patients with stroke and Moyamoya disease. In Study 1, 20 stroke patients (56.3 ± 9.7 years, 7 females) were enrolled and resting-state blood‑oxygenation-level-dependent (rs-BOLD) fMRI data were collected, from which CVR maps were computed. CVR values were compared across lesion, perilesional and control ROIs defined on anatomic images. Reproducibility of the CVR measurement was tested in 6 patients with follow-up scans. In Study 2, rs-BOLD fMRI and dynamic susceptibility contrast (DSC) MRI scans were collected in 5 patients with Moyamoya disease (32.4 ± 8.2 years, 4 females). Cerebral blood flow (CBF), cerebral blood volume (CBV), and time-to-peak (TTP) maps were obtained from the DSC MRI data. CVR values were compared between stenotic brain regions and control regions perfused by non-stenotic arteries. RESULTS In stroke patients, lesion CVR (0.250 ± 0.055 relative unit (r.u.)) was lower than control CVR (0.731 ± 0.088 r.u., p = 0.0002). CVR was also lower in the perilesional regions in a graded manner (perilesion 1 CVR = 0.422 ± 0.051 r.u., perilesion 2 CVR = 0.492 ± 0.046 r.u.), relative to that in the control regions (p = 0.005 and 0.036, respectively). In the repeatability analysis, a strong correlation was observed between lesion CVR (r2 = 0.91, p = 0.006) measured at two time points, as well as between control CVR (r2 = 0.79, p = 0.036) at two time points. In Moyamoya patients, CVR in the perfusion deficit regions delineated by DSC TTP maps (0.178 ± 0.189 r.u.) was lower than that in the control regions (0.868 ± 0.214 r.u., p = 0.013). Furthermore, the extent of reduction in CVR was significantly correlated with the extent of lengthening in TTP (r2 = 0.91, p = 0.033). CONCLUSION Our findings suggested that rs-BOLD data can be used to reproducibly evaluate CVR in patients with cerebrovascular diseases without the use of any vasoactive challenges.
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Agarwal S, Sair HI, Gujar S, Hua J, Lu H, Pillai JJ. Functional Magnetic Resonance Imaging Activation Optimization in the Setting of Brain Tumor-Induced Neurovascular Uncoupling Using Resting-State Blood Oxygen Level-Dependent Amplitude of Low Frequency Fluctuations. Brain Connect 2019; 9:241-250. [PMID: 30547681 DOI: 10.1089/brain.2017.0562] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The goal of this study was to demonstrate that a novel resting state BOLD ALFF (amplitude of low frequency fluctuations)-based correction method can substantially enhance the detectability of motor task activation in the presence of tumor-induced neurovascular uncoupling (NVU). Twelve de novo brain tumor patients who underwent comprehensive clinical BOLD fMRI exams including task fMRI and resting state fMRI (rsfMRI) were evaluated. Each patient displayed decreased/absent task fMRI activation in the ipsilesional primary motor cortex in the absence of corresponding motor deficit or suboptimal task performance, consistent with NVU. Z-score maps for the motor tasks were obtained from general linear model (GLM) analysis (reflecting motor activation vs. rest). ALFF maps were calculated from rsfMRI data. Precentral and postcentral gyri in contralesional (CL) and ipsilesional (IL) hemispheres were parcellated using an Automated Anatomical Labeling (AAL) template for each patient. A novel ALFF-based correction method was used to identify the NVU affected voxels in the ipsilesional primary motor cortex (PMC), and a correction factor was applied to normalize the baseline Z-scores for these voxels. In all cases, substantially greater activation was seen on post-ALFF correction motor activation maps within the ipsilesional precentral gyri than in the pre-ALFF correction activation maps. We have demonstrated the feasibility of a new resting state ALFF-based technique for effective correction of brain tumor-related NVU in the primary motor cortex.
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Affiliation(s)
- Shruti Agarwal
- 1 Divisions of Neuroradiology and Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Haris I Sair
- 1 Divisions of Neuroradiology and Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Sachin Gujar
- 1 Divisions of Neuroradiology and Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Jun Hua
- 2 Divisions of MR Research, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland.,3 F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland
| | - Hanzhang Lu
- 2 Divisions of MR Research, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland.,3 F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland
| | - Jay J Pillai
- 1 Divisions of Neuroradiology and Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland.,4 Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
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Hou X, Liu P, Gu H, Chan M, Li Y, Peng SL, Wig G, Yang Y, Park D, Lu H. Estimation of brain functional connectivity from hypercapnia BOLD MRI data: Validation in a lifespan cohort of 170 subjects. Neuroimage 2018; 186:455-463. [PMID: 30463025 DOI: 10.1016/j.neuroimage.2018.11.028] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Revised: 10/31/2018] [Accepted: 11/16/2018] [Indexed: 01/07/2023] Open
Abstract
Functional connectivity MRI, based on Blood-Oxygenation-Level-Dependent (BOLD) signals, is typically performed while the subject is at rest. On the other hand, BOLD is also widely used in physiological imaging such as cerebrovascular reactivity (CVR) mapping using hypercapnia (HC) as a modulator. We therefore hypothesize that hypercapnia BOLD data can be used to extract FC metrics after factoring out the effects of the physiological modulation, which will allow simultaneous assessment of neural and vascular function and may be particularly important in populations such as aging and cerebrovascular diseases. The present work aims to systematically examine the feasibility of hypercapnia BOLD-based FC mapping using three commonly applied analysis methods, specifically dual-regression Independent Component Analysis (ICA), region-based FC matrix analysis, and graph-theory based network analysis, in a large cohort of 170 healthy subjects ranging from 20 to 88 years old. To validate the hypercapnia BOLD results, we also compared these FC metrics with those obtained from conventional resting-state data. ICA analysis of the hypercapnia BOLD data revealed FC maps that strongly resembled those reported in the literature. FC matrix using region-based analysis showed a correlation of 0.97 on the group-level and 0.54 ± 0.10 on the individual-level, when comparing between hypercapnia and resting-state results. Although the correspondence on the individual-level was moderate, this was primarily attributed to variations intrinsic to FC mapping, because a corresponding resting-vs-resting comparison in a sub-cohort (N = 39) revealed a similar correlation of 0.57 ± 0.09. Graph-theory computations were also feasible in hypercapnia BOLD data and indices of global efficiency, clustering coefficient, modularity, and segregation were successfully derived. Hypercapnia FC results revealed age-dependent differences in which within-network connections generally exhibited an age-dependent decrease while between-network connections showed an age-dependent increase.
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Affiliation(s)
- Xirui Hou
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Peiying Liu
- The Russell H. Morgan Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
| | - Hong Gu
- Neuroimaging Research Branch, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Micaela Chan
- Center for Vital Longevity, School of Behavioral and Brain Sciences, University of Texas at Dallas, Dallas, TX, USA
| | - Yang Li
- The Russell H. Morgan Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Graduate School of Biomedical Sciences, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Shin-Lei Peng
- The Russell H. Morgan Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Biomedical Imaging and Radiological Science, China Medical University, Taichung, Taiwan
| | - Gagan Wig
- Center for Vital Longevity, School of Behavioral and Brain Sciences, University of Texas at Dallas, Dallas, TX, USA; Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Yihong Yang
- Neuroimaging Research Branch, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Denise Park
- Center for Vital Longevity, School of Behavioral and Brain Sciences, University of Texas at Dallas, Dallas, TX, USA; Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Hanzhang Lu
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA; The Russell H. Morgan Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA.
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Mayer AR, Kaushal M, Dodd AB, Hanlon FM, Shaff NA, Mannix R, Master CL, Leddy JJ, Stephenson D, Wertz CJ, Suelzer EM, Arbogast KB, Meier TB. Advanced biomarkers of pediatric mild traumatic brain injury: Progress and perils. Neurosci Biobehav Rev 2018; 94:149-165. [PMID: 30098989 DOI: 10.1016/j.neubiorev.2018.08.002] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 07/27/2018] [Accepted: 08/03/2018] [Indexed: 12/20/2022]
Abstract
There is growing public concern about neurodegenerative changes (e.g., Chronic Traumatic Encephalopathy) that may occur chronically following clinically apparent and clinically silent (i.e., sub-concussive blows) pediatric mild traumatic brain injury (pmTBI). However, there are currently no biomarkers that clinicians can use to objectively diagnose patients or predict those who may struggle to recover. Non-invasive neuroimaging, electrophysiological and neuromodulation biomarkers have promise for providing evidence of the so-called "invisible wounds" of pmTBI. Our systematic review, however, belies that notion, identifying a relative paucity of high-quality, clinically impactful, diagnostic or prognostic biomarker studies in the sub-acute injury phase (36 studies on unique samples in 28 years), with the majority focusing on adolescent pmTBI. Ultimately, well-powered longitudinal studies with appropriate control groups, as well as standardized and clearly-defined inclusion criteria (time post-injury, injury severity and past history) are needed to truly understand the complex pathophysiology that is hypothesized (i.e., still needs to be determined) to exist during the acute and sub-acute stages of pmTBI and may underlie post-concussive symptoms.
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Affiliation(s)
- Andrew R Mayer
- The Mind Research Network/Lovelace Biomedical and Environmental Research Institute, Pete & Nancy Domenici Hall, 1011 Yale Blvd. NE, Albuquerque, NM, 87106, United States; Neurology Department, University of New Mexico School of Medicine, Albuquerque, NM, 87131, United States; Psychiatry Department, University of New Mexico School of Medicine, Albuquerque, NM, 87131, United States; Psychology Department, University of New Mexico, Albuquerque, NM, 87131, United States.
| | - Mayank Kaushal
- Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, WI, 53226, United States
| | - Andrew B Dodd
- The Mind Research Network/Lovelace Biomedical and Environmental Research Institute, Pete & Nancy Domenici Hall, 1011 Yale Blvd. NE, Albuquerque, NM, 87106, United States
| | - Faith M Hanlon
- The Mind Research Network/Lovelace Biomedical and Environmental Research Institute, Pete & Nancy Domenici Hall, 1011 Yale Blvd. NE, Albuquerque, NM, 87106, United States
| | - Nicholas A Shaff
- The Mind Research Network/Lovelace Biomedical and Environmental Research Institute, Pete & Nancy Domenici Hall, 1011 Yale Blvd. NE, Albuquerque, NM, 87106, United States
| | - Rebekah Mannix
- Division of Emergency Medicine, Boston Children's Hospital, Boston, MA, 02115, United States
| | - Christina L Master
- Center for Injury Research and Prevention, The Children's Hospital of Philadelphia, PA, 19104, United States; Division of Orthopedic Surgery, The Children's Hospital of Philadelphia, Philadelphia, PA, 19104, United States
| | - John J Leddy
- UBMD Department of Orthopaedics and Sports Medicine, University at Buffalo, Buffalo, NY, 14214, United States
| | - David Stephenson
- The Mind Research Network/Lovelace Biomedical and Environmental Research Institute, Pete & Nancy Domenici Hall, 1011 Yale Blvd. NE, Albuquerque, NM, 87106, United States
| | - Christopher J Wertz
- The Mind Research Network/Lovelace Biomedical and Environmental Research Institute, Pete & Nancy Domenici Hall, 1011 Yale Blvd. NE, Albuquerque, NM, 87106, United States
| | - Elizabeth M Suelzer
- Medical College of Wisconsin Libraries, Medical College of Wisconsin, Milwaukee, WI, 53226, United States
| | - Kristy B Arbogast
- Center for Injury Research and Prevention, The Children's Hospital of Philadelphia, PA, 19104, United States
| | - Timothy B Meier
- Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, WI, 53226, United States; Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, 53226, United States
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27
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Sheng M, Lu H, Liu P, Li Y, Ravi H, Peng SL, Diaz-Arrastia R, Devous MD, Womack KB. Sildenafil Improves Vascular and Metabolic Function in Patients with Alzheimer's Disease. J Alzheimers Dis 2018; 60:1351-1364. [PMID: 29036811 DOI: 10.3233/jad-161006] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
BACKGROUND Alzheimer's disease (AD) is the leading cause of degenerative dementia in the aging population. Patients with AD have alterations in cerebral hemodynamic function including reduced cerebral blood flow (CBF) and cerebral metabolic rate. Therefore, improved cerebrovascular function may be an attractive goal for pharmaceutical intervention in AD. OBJECTIVE We wished to observe the acute effects of sildenafil on cerebrovascular function and brain metabolism in patients with AD. METHODS We used several novel non-invasive MRI techniques to investigate the alterations of CBF, cerebral metabolic rate of oxygen (CMRO2), and cerebrovascular reactivity (CVR) after a single dose of sildenafil administration in order to assess its physiological effects in patients with AD. CBF, CMRO2, and CVR measurements using MRI were performed before and one hour after the oral administration of 50 mg sildenafil. Baseline Montreal Cognitive Assessment score was also obtained. RESULTS Complete CBF and CMRO2 data were obtained in twelve patients. Complete CVR data were obtained in eight patients. Global CBF and CMRO2 significantly increased (p = 0.03, p = 0.05, respectively) following sildenafil administration. Voxel-wise analyses of CBF maps showed that increased CBF was most pronounced in the bilateral medial temporal lobes. CVR significantly decreased after administration of sildenafil. CONCLUSION Our data suggest that a single dose of sildenafil improves cerebral hemodynamic function and increases cerebral oxygen metabolism in patients with AD.
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Affiliation(s)
- Min Sheng
- Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, TX, USA.,Department of Radiology, Beijing Eden Hospital, Beijing, China
| | - Hanzhang Lu
- Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, TX, USA.,Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Peiying Liu
- Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, TX, USA.,Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Yang Li
- Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, TX, USA.,Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Harshan Ravi
- Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, TX, USA.,Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Shin-Lei Peng
- Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, TX, USA.,Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA.,Department of Biomedical Imaging and Radiological Science, China Medical University, Taichung, Taiwan
| | - Ramon Diaz-Arrastia
- Department of Neurology, University of Pennsylvania Perelman School of Medicine, Penn Presbyterian Medical Center, Philadelphia, PA, USA
| | - Michael D Devous
- Department of Neurology and Neurotherapeutics, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Kyle B Womack
- Department of Neurology and Neurotherapeutics, The University of Texas Southwestern Medical Center, Dallas, TX, USA.,Department of Psychiatry, The University of Texas Southwestern Medical Center, Dallas, TX, USA
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28
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Catchlove SJ, Parrish TB, Chen Y, Macpherson H, Hughes ME, Pipingas A. Regional Cerebrovascular Reactivity and Cognitive Performance in Healthy Aging. J Exp Neurosci 2018; 12:1179069518785151. [PMID: 30013388 PMCID: PMC6043917 DOI: 10.1177/1179069518785151] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Accepted: 06/03/2018] [Indexed: 12/21/2022] Open
Abstract
Cerebrovascular reactivity (CVR) reflects the response of brain blood vessels to vasoactive stimuli, such as neural activity. The current research assessed age-related changes in regional CVR to 5% CO2 inhalation in younger (n = 30, range: 21-45 years) and older (n = 29, range: 55-75 years) adults, and the contribution of regional CVR to cognitive performance using blood-oxygen-level dependent contrast imaging (BOLD) functional magnetic resonance imaging (fMRI) at 3T field strength. CVR was measured by inducing hypercapnia using a block-design paradigm under physiological monitoring. Memory and attention were assessed with a comprehensive computerized aging battery. MRI data analysis was conducted using MATLAB® and SPM12. Memory and attention performance was positively associated with CVR in the temporal cortices. Temporal lobe CVR influenced memory performance independently of age, gender, and education level. When analyzing age groups separately, CVR in the hippocampus contributed significantly to memory score in the older group and was also related to subjective memory complaints. No associations between CVR and cognition were observed in younger adults. Vascular responsiveness in the brain has consequences for cognition in cognitively healthy people. These findings may inform other areas of research concerned with vaso-protective approaches for prevention or treatment of neurocognitive decline.
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Affiliation(s)
- Sarah J Catchlove
- Centre for Human Psychopharmacology,
Swinburne University, Hawthorn, VIC, Australia
| | - Todd B Parrish
- Feinberg School of Medicine,
Northwestern University, Chicago, IL, USA
| | - Yufen Chen
- Feinberg School of Medicine,
Northwestern University, Chicago, IL, USA
| | - Helen Macpherson
- Institute for Physical Activity and
Nutrition, Deakin University, Geelong, VIC, Australia
| | - Matthew E Hughes
- Centre for Mental Health, Swinburne
University, Hawthorn, VIC, Australia
- Australian National Imaging Facility, St
Lucia, QLD, Australia
| | - Andrew Pipingas
- Centre for Human Psychopharmacology,
Swinburne University, Hawthorn, VIC, Australia
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29
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Haber M, Amyot F, Kenney K, Meredith-Duliba T, Moore C, Silverman E, Podell J, Chou YY, Pham DL, Butman J, Lu H, Diaz-Arrastia R, Sandsmark D. Vascular Abnormalities within Normal Appearing Tissue in Chronic Traumatic Brain Injury. J Neurotrauma 2018; 35:2250-2258. [PMID: 29609518 DOI: 10.1089/neu.2018.5684] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022] Open
Abstract
Magnetic resonance imaging (MRI) is a powerful tool for visualizing traumatic brain injury(TBI)-related lesions. Trauma-induced encephalomalacia is frequently identified by its hyperintense appearance on fluid-attenuated inversion recovery (FLAIR) sequences. In addition to parenchymal lesions, TBI commonly results in cerebral microvascular injury, but its anatomical relationship to parenchymal encephalomalacia is not well characterized. The current study utilized a multi-modal MRI protocol to assess microstructural tissue integrity (by mean diffusivity [MD] and fractional aniosotropy [FA]) and altered vascular function (by cerebral blood flow [CBF] and cerebral vascular reactivity [CVR]) within regions of visible encephalomalacia and normal appearing tissue in 27 chronic TBI (minimum 6 months post-injury) subjects. Fifteen subjects had visible encephalomalacias whereas 12 did not have evident lesions on MRI. Imaging from 14 age-matched healthy volunteers were used as controls. CBF was assessed by arterial spin labeling (ASL) and CVR by measuring the change in blood-oxygen-level-dependent (BOLD) MRI during a hypercapnia challenge. There was a significant reduction in FA, CBF, and CVR with a complementary increase in MD within regions of FLAIR-visible encephalomalacia (p < 0.05 for all comparisons). In normal-appearing brain regions, only CVR was significantly reduced relative to controls (p < 0.05). These findings indicate that vascular dysfunction represents a TBI endophenotype that is distinct from structural injury detected using conventional MRI, may be present even in the absence of visible structural injury, and persists long after trauma. CVR may serve as a useful diagnostic and pharmacodynamic imaging biomarker of traumatic microvascular injury.
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Affiliation(s)
- Margalit Haber
- 1 Department of Neurology, University of Pennsylvania Perelman School of Medicine , Philadelphia, Pennsylvania
| | - Franck Amyot
- 6 National Intrepid Center of Excellence, Walter Reed National Military Medical Center, Bethesda, Maryland
| | - Kimbra Kenney
- 2 Department of Neurology, Uniformed Services University of the Health Sciences , Bethesda, Maryland
| | - Tawny Meredith-Duliba
- 1 Department of Neurology, University of Pennsylvania Perelman School of Medicine , Philadelphia, Pennsylvania
| | - Carol Moore
- 2 Department of Neurology, Uniformed Services University of the Health Sciences , Bethesda, Maryland
| | - Erika Silverman
- 1 Department of Neurology, University of Pennsylvania Perelman School of Medicine , Philadelphia, Pennsylvania
| | - Jamie Podell
- 1 Department of Neurology, University of Pennsylvania Perelman School of Medicine , Philadelphia, Pennsylvania
| | - Yi-Yu Chou
- 3 Center for Neuroscience and Regenerative Medicine , Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, Maryland
| | - Dzung L Pham
- 3 Center for Neuroscience and Regenerative Medicine , Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, Maryland
| | - John Butman
- 4 National Institutes of Health , Clinical Center, Radiology and Imaging Sciences, Bethesda, Maryland
| | - Hanzhang Lu
- 5 Department of Radiology, Johns Hopkins University Baltimore , Maryland
| | - Ramon Diaz-Arrastia
- 1 Department of Neurology, University of Pennsylvania Perelman School of Medicine , Philadelphia, Pennsylvania
| | - Danielle Sandsmark
- 1 Department of Neurology, University of Pennsylvania Perelman School of Medicine , Philadelphia, Pennsylvania
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30
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Kenney K, Amyot F, Moore C, Haber M, Turtzo LC, Shenouda C, Silverman E, Gong Y, Qu BX, Harburg L, Wassermann EM, Lu H, Diaz‐Arrastia R. Phosphodiesterase-5 inhibition potentiates cerebrovascular reactivity in chronic traumatic brain injury. Ann Clin Transl Neurol 2018; 5:418-428. [PMID: 29687019 PMCID: PMC5899908 DOI: 10.1002/acn3.541] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 12/12/2017] [Accepted: 12/26/2017] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Traumatic cerebrovascular injury (TCVI), a common consequence of traumatic brain injury (TBI), presents an attractive therapeutic target. Because phosphodiesterase-5 (PDE5) inhibitors potentiate the action of nitric oxide (NO) produced by endothelial cells, they are candidate therapies for TCVI. This study aims to: (1) measure cerebral blood flow (CBF), cerebrovascular reactivity (CVR), and change in CVR after a single dose of sildenafil (ΔCVR) in chronic TBI compared to uninjured controls; (2) examine the safety and tolerability of 8-week sildenafil administration in chronic symptomatic moderate/severe TBI patients; and as an exploratory aim, (3) assess the effect of an 8-week course of sildenafil on chronic TBI symptoms. METHODS Forty-six subjects (31 chronic TBI, 15 matched healthy volunteers) were enrolled. Baseline CBF and CVR before and after administration of sildenafil were measured. Symptomatic TBI subjects then completed an 8-week double-blind, placebo-controlled, crossover trial of sildenafil. A neuropsychological battery and neurobehavioral symptom questionnaires were administered at each study visit. RESULTS After a single dose of sildenafil, TBI subjects showed a significant increase in global CVR compared to healthy controls (P < 0.001, d = 0.9). Post-sildenafil CVR maps showed near-normalization of CVR in many regions where baseline CVR was low, predominantly within areas without structural abnormalities. Sildenafil was well tolerated. Clinical Global Impression (CGI) scale showed a trend toward clinical improvement while on sildenafil treatment. FINDINGS Single-dose sildenafil improves regional CVR deficits in chronic TBI patients. CVR and ΔCVR are potential predictive and pharmacodynamic biomarkers of PDE5 inhibitor therapy for TCVI. Sildenafil is a potential therapy for TCVI.
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Affiliation(s)
- Kimbra Kenney
- Department of NeurologyUniformed Services University of the Health SciencesBethesdaMaryland
| | - Franck Amyot
- Department of NeurologyUniformed Services University of the Health SciencesBethesdaMaryland
| | - Carol Moore
- Department of NeurologyUniformed Services University of the Health SciencesBethesdaMaryland
| | - Margalit Haber
- Department of NeurologyUniversity of Pennsylvania Perelman School of MedicinePhiladelphiaPennsylvania
| | | | - Christian Shenouda
- Department of Physical Medicine and RehabilitationNational Institutes of Health Clinical CenterBethesdaMaryland
| | - Erika Silverman
- Department of NeurologyUniversity of Pennsylvania Perelman School of MedicinePhiladelphiaPennsylvania
| | - Yunhua Gong
- Department of NeurologyUniversity of Pennsylvania Perelman School of MedicinePhiladelphiaPennsylvania
| | - Bao‐ Xi Qu
- Department of NeurologyUniformed Services University of the Health SciencesBethesdaMaryland
| | - Leah Harburg
- Department of NeurologyUniformed Services University of the Health SciencesBethesdaMaryland
| | - Eric M. Wassermann
- Behavioral Neurology UnitNational Institute of Neurological Diseases and StrokeNational Institutes of HealthBethesdaMaryland
| | | | - Ramon Diaz‐Arrastia
- Department of NeurologyUniversity of Pennsylvania Perelman School of MedicinePhiladelphiaPennsylvania
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31
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De Vis JB, Lu H, Ravi H, Hendrikse J, Liu P. Spatial distribution of flow and oxygenation in the cerebral venous drainage system. J Magn Reson Imaging 2018; 47:1091-1098. [PMID: 28791759 PMCID: PMC5807233 DOI: 10.1002/jmri.25833] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 07/25/2017] [Indexed: 12/16/2022] Open
Abstract
PURPOSE To investigate the venous oxygenation and flow in the brain, and determine how they might change under challenged states. MATERIALS AND METHODS Eight healthy human subjects (24-37 years) were studied. T2 -relaxation under spin tagging (TRUST) magnetic resonance imaging (MRI) and phase-contrast MRI were performed to measure venous oxygenation and venous blood flow, respectively, in the superior sagittal sinus (SSS), the straight sinus (SS), and the internal jugular veins (IJVs). Venous oxygenation was assessed at room air (0.03%CO2 , 21%O2 ) and under hyperoxia (O%CO2 , 95%O2 , and 5%N2 ) conditions. Venous blood flow was assessed at room air and under hypercapnia (5%CO2 , 21%O2 , and 74%N2 ) conditions. Whole-brain blood flow was also measured at the four feeding arteries of the brain using phase-contrast MRI. The changes in venous oxygenation and blood flow from room air to hyperoxia or hypercapnia conditions were tested using paired t-tests. RESULTS Venous oxygenation in the SSS, the SS, and the IJVs was 61 ± 4%, 64 ± 4%, and 62 ± 4%, respectively, at room air, and increased to 70 ± 3% (P < 0.01 compared to room air), 71 ± 5% (P = 0.59), and 68 ± 5% (P < 0.05) under hyperoxic condition. The SSS, SS, and IJV drained 46 ± 9%, 16 ± 4%, and 79 ± 1% of whole-brain blood flow, respectively, and this flow distribution did not change under hypercapnic condition (P > 0.5). CONCLUSION The results found in this study provide insight into the venous oxygenation and venous flow distribution and its heterogeneity among different venous structures. LEVEL OF EVIDENCE 1 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018;47:1091-1098.
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Affiliation(s)
- Jill B. De Vis
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Hanzhang Lu
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Harshan Ravi
- Center for Neuroscience and Regenerative Medicine, National Institutes of Health, Bethesda, MD
| | - Jeroen Hendrikse
- Department of Radiology, University Medical Center Utrecht, The Netherlands
| | - Peiying Liu
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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32
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Liu P, De Vis JB, Lu H. Cerebrovascular reactivity (CVR) MRI with CO2 challenge: A technical review. Neuroimage 2018; 187:104-115. [PMID: 29574034 DOI: 10.1016/j.neuroimage.2018.03.047] [Citation(s) in RCA: 136] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 02/06/2018] [Accepted: 03/19/2018] [Indexed: 11/16/2022] Open
Abstract
Cerebrovascular reactivity (CVR) is an indicator of cerebrovascular reserve and provides important information about vascular health in a range of brain conditions and diseases. Unlike steady-state vascular parameters, such as cerebral blood flow (CBF) and cerebral blood volume (CBV), CVR measures the ability of cerebral vessels to dilate or constrict in response to challenges or maneuvers. Therefore, CVR mapping requires a physiological challenge while monitoring the corresponding hemodynamic changes in the brain. The present review primarily focuses on methods that use CO2 inhalation as a physiological challenge while monitoring changes in hemodynamic MRI signals. CO2 inhalation has been increasingly used in CVR mapping in recent literature due to its potency in causing vasodilation, rapid onset and cessation of the effect, as well as advances in MRI-compatible gas delivery apparatus. In this review, we first discuss the physiological basis of CVR mapping using CO2 inhalation. We then review the methodological aspects of CVR mapping, including gas delivery apparatus, the timing paradigm of the breathing challenge, the MRI imaging sequence, and data analysis. In addition, we review alternative approaches for CVR mapping that do not require CO2 inhalation.
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Affiliation(s)
- Peiying Liu
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, 21287, United States.
| | - Jill B De Vis
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, 21287, United States
| | - Hanzhang Lu
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, 21287, United States; Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, 21287, United States; F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, 21205, United States
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33
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Amyot F, Kenney K, Moore C, Haber M, Turtzo LC, Shenouda C, Silverman E, Gong Y, Qu BX, Harburg L, Lu HY, Wassermann EM, Diaz-Arrastia R. Imaging of Cerebrovascular Function in Chronic Traumatic Brain Injury. J Neurotrauma 2018; 35:1116-1123. [PMID: 29065769 DOI: 10.1089/neu.2017.5114] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Traumatic cerebrovascular injury (TCVI) is a common pathologic mechanism of traumatic brain injury (TBI) and presents an attractive target for intervention. The aims of this study were to assess cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) using magnetic resonance imaging (MRI) to assess their value as biomarkers of TCVI in chronic TBI, characterize the spatial distribution of TCVI, and assess the relationships between each biomarker and neuropsychological and clinical assessments. Forty-two subjects (27 chronic TBI, 15 age- and gender-matched healthy volunteers) were studied cross-sectionally. CBF was measured by arterial spin labeling and CVR by assessing the MRI-blood oxygen level-dependent signal with hypercapnia challenge. A focused neuropsychological battery adapted from the TBI Common Data Elements and neurobehavioral symptom questionnaires were administered at the time of the imaging session. Chronic TBI subjects showed a significant reduction in mean global, gray matter (GM), and white matter (WM) CVR, compared with healthy volunteers (p < 0.001). Mean GM CVR had the greatest effect size (Cohen's d = 0.9). CVR maps in chronic TBI subjects showed patchy, multifocal CVR deficits. CBF discriminated poorly between TBI subjects and healthy volunteers and did not correlate with CVR. Mean global CVR correlated best with chronic neurobehavioral symptoms among TBI subjects. Global, GM, and WM CVR are reliable and potentially useful biomarkers of TCVI in the chronic stage after moderate-to-severe TBI. CBF is less useful as biomarker of TCVI. CVR correlates best with chronic TBI symptoms. CVR has potential as a predictive and pharmacodynamic biomarker for interventions targeting TCVI.
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Affiliation(s)
- Franck Amyot
- 1 Department of Neurology, Uniformed Services University of the Health Sciences , Bethesda, Maryland
| | - Kimbra Kenney
- 1 Department of Neurology, Uniformed Services University of the Health Sciences , Bethesda, Maryland
| | - Carol Moore
- 1 Department of Neurology, Uniformed Services University of the Health Sciences , Bethesda, Maryland
| | - Margalit Haber
- 2 Department of Neurology, University of Pennsylvania Perelman School of Medicine , Philadelphia, Pennsylvania
| | - L Christine Turtzo
- 3 Center for Neuroscience and Regenerative Medicine, National Institute of Neurological Disorder and Stroke, National Institutes of Health , Bethesda, Maryland
| | - Christian Shenouda
- 3 Center for Neuroscience and Regenerative Medicine, National Institute of Neurological Disorder and Stroke, National Institutes of Health , Bethesda, Maryland
| | - Erika Silverman
- 2 Department of Neurology, University of Pennsylvania Perelman School of Medicine , Philadelphia, Pennsylvania
| | - Yunhua Gong
- 2 Department of Neurology, University of Pennsylvania Perelman School of Medicine , Philadelphia, Pennsylvania
| | - Bao-Xi Qu
- 1 Department of Neurology, Uniformed Services University of the Health Sciences , Bethesda, Maryland
| | - Leah Harburg
- 1 Department of Neurology, Uniformed Services University of the Health Sciences , Bethesda, Maryland
| | - Hanzhang Y Lu
- 4 Department of Radiology and Radiological Science, Johns Hopkins University Baltimore , Maryland
| | - Eric M Wassermann
- 5 National Institute of Neurological Disorders and Stroke, National Institutes of Health , Bethesda, Maryland
| | - Ramon Diaz-Arrastia
- 2 Department of Neurology, University of Pennsylvania Perelman School of Medicine , Philadelphia, Pennsylvania
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34
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Lin Z, Li Y, Su P, Mao D, Wei Z, Pillai JJ, Moghekar A, van Osch M, Ge Y, Lu H. Non-contrast MR imaging of blood-brain barrier permeability to water. Magn Reson Med 2018; 80:1507-1520. [PMID: 29498097 DOI: 10.1002/mrm.27141] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Revised: 01/05/2018] [Accepted: 01/29/2018] [Indexed: 12/18/2022]
Abstract
PURPOSE Many brain diseases are associated with an alteration in blood-brain barrier (BBB) and its permeability. Current methods using contrast agent are primarily sensitive to major leakage of BBB to macromolecules, but may not detect subtle changes in BBB permeability. The present study aims to develop a novel non-contrast MRI technique for the assessment of BBB permeability to water. METHODS The central principle is that by measuring arterially labeled blood spins that are drained into cerebral veins, water extraction fraction (E) and permeability-surface-area product (PS) of BBB can be determined. Four studies were performed. We first demonstrated the proof-of-principle using conventional ASL with very long post-labeling delays (PLD). Next, a new sequence, dubbed water-extraction-with-phase-contrast-arterial-spin-tagging (WEPCAST), and its Look-Locker (LL) version were developed. Finally, we demonstrated that the sensitivity of the technique can be significantly enhanced by acquiring the data under mild hypercapnia. RESULTS By combining a strong background suppression with long PLDs (2500-4500 ms), ASL spins were reliably detected in the superior sagittal sinus (SSS), demonstrating the feasibility of measuring this signal. The WEPCAST sequence eliminated partial voluming effects of tissue perfusion and allowed quantitative estimation of E = 95.5 ± 1.1% and PS = 188.9 ± 13.4 mL/100 g/min, which were in good agreement with literature reports. LL-WEPCAST sequence shortened the scan time from 19 min to 5 min while providing results consistent with multiple single-PLD acquisitions. Mild hypercapnia increased SNR by 78 ± 25% without causing a discomfort in participants. CONCLUSION A new non-contrast technique for the assessment of global BBB permeability was developed, which may have important clinical applications.
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Affiliation(s)
- Zixuan Lin
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Yang Li
- The Russell H. Morgan Department of Radiology & Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland.,Graduate School of Biomedical Sciences, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Pan Su
- The Russell H. Morgan Department of Radiology & Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland.,Graduate School of Biomedical Sciences, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Deng Mao
- The Russell H. Morgan Department of Radiology & Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland.,Graduate School of Biomedical Sciences, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Zhiliang Wei
- The Russell H. Morgan Department of Radiology & Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute, Baltimore, Maryland
| | - Jay J Pillai
- The Russell H. Morgan Department of Radiology & Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland.,Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Abhay Moghekar
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Matthias van Osch
- Department of Radiology, C. J. Gorter Center for High Field MRI, Leiden University Medical Center, Leiden, the Netherlands
| | - Yulin Ge
- Department of Radiology, New York University Langone Medical Center, New York, New York
| | - Hanzhang Lu
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland.,The Russell H. Morgan Department of Radiology & Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute, Baltimore, Maryland
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35
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Metzger A, Le Bars E, Deverdun J, Molino F, Maréchal B, Picot MC, Ayrignac X, Carra C, Bauchet L, Krainik A, Labauge P, Menjot de Champfleur N. Is impaired cerebral vasoreactivity an early marker of cognitive decline in multiple sclerosis patients? Eur Radiol 2017; 28:1204-1214. [PMID: 29026971 DOI: 10.1007/s00330-017-5068-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 08/27/2017] [Accepted: 09/08/2017] [Indexed: 11/25/2022]
Abstract
OBJECTIVE The link between cerebral vasoreactivity and cognitive status in multiple sclerosis remains unclear. The aim of the present study was to investigate a potential decrease of cerebral vasoreactivity in multiple sclerosis patients and correlate it with cognitive status. METHODS Thirty-three patients with multiple sclerosis (nine progressive and 24 remitting forms, median age: 39 years, 12 males) and 22 controls underwent MRI with a hypercapnic challenge to assess cerebral vasoreactivity and a neuropsychological assessment. Cerebral vasoreactivity, measured as the cerebral blood flow percent increase normalised by end-tidal carbon dioxide variation, was assessed globally and by regions of interest using the blood oxygen level-dependent technique. Non-parametric statistics tests were used to assess differences between groups, and associations were estimated using linear models. RESULTS Cerebral vasoreactivity was lower in patients with cognitive impairment than in cognitively normal patients (p=0.004) and was associated with education level in patients (R2 = 0.35; p = 0.047). There was no decrease in cerebral vasoreactivity between patients and controls. CONCLUSIONS Cognitive impairment in multiple sclerosis may be mediated through decreased cerebral vasoreactivity. Cerebral vasoreactivity could therefore be considered as a marker of cognitive decline in multiple sclerosis. KEY POINTS • Cerebral vasoreactivity does not differ between multiple sclerosis patients and controls. • Cerebral vasoreactivity measure is linked to cognitive impairment in multiple sclerosis. • Cerebral vasoreactivity is linked to level of education in multiple sclerosis.
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Affiliation(s)
- Aude Metzger
- Department of Neurology, University Hospital Center, Gui de Chauliac Hospital, Montpellier, France.
- Department of Neurology, Memory Ressource and Research Center, University Hospital Center, Gui de Chauliac Hospital, 80 Avenue Augustin Fliche, 34295, Montpellier Cedex 5, France.
| | - Emmanuelle Le Bars
- Département de Neuroradiologie, Hôpital Gui de Chauliac, Centre Hospitalier Régional Universitaire de Montpellier, Montpellier, France
- Institut d'Imagerie Fonctionnelle Humaine (I2FH), Hôpital Gui de Chauliac, Centre Hospitalier Régional Universitaire de Montpellier, Montpellier, France
- Laboratoire Charles Coulomb, CNRS UMR 5221, Université de Montpellier, Montpellier, France
| | - Jeremy Deverdun
- Département de Neuroradiologie, Hôpital Gui de Chauliac, Centre Hospitalier Régional Universitaire de Montpellier, Montpellier, France
- Institut d'Imagerie Fonctionnelle Humaine (I2FH), Hôpital Gui de Chauliac, Centre Hospitalier Régional Universitaire de Montpellier, Montpellier, France
- Laboratoire Charles Coulomb, CNRS UMR 5221, Université de Montpellier, Montpellier, France
| | - François Molino
- Laboratoire Charles Coulomb, CNRS UMR 5221, Université de Montpellier, Montpellier, France
- Institut de Génomique Fonctionnelle, CNRS UMR 5203, INSERM U661, Université de Montpellier, Montpellier, France
| | - Bénédicte Maréchal
- Advanced Clinical Imaging Technology, Siemens Healthcare, HC CEMEA SUI DI, Lausanne, PI, Switzerland
- Department of Radiology, CHUV, Lausanne, Switzerland
- LTS5, EPFL, Lausanne, Switzerland
| | - Marie-Christine Picot
- Département de Biostatistiques, Centre Hospitalier Régional Universitaire de Montpellier, Montpellier, France
| | - Xavier Ayrignac
- Department of Neurology, University Hospital Center, Gui de Chauliac Hospital, Montpellier, France
| | - Clarisse Carra
- Department of Neurology, University Hospital Center, Gui de Chauliac Hospital, Montpellier, France
| | - Luc Bauchet
- Département de Neurochirurgie, Hôpital Gui de Chauliac, Centre Hospitalier Régional Universitaire de Montpellier, Montpellier, France
- Institut de Neurosciences de Montpellier, INSERM U1051, Hôpital Saint Eloi, Montpellier, France
| | | | - Pierre Labauge
- Department of Neurology, University Hospital Center, Gui de Chauliac Hospital, Montpellier, France
| | - Nicolas Menjot de Champfleur
- Département de Neuroradiologie, Hôpital Gui de Chauliac, Centre Hospitalier Régional Universitaire de Montpellier, Montpellier, France
- Institut d'Imagerie Fonctionnelle Humaine (I2FH), Hôpital Gui de Chauliac, Centre Hospitalier Régional Universitaire de Montpellier, Montpellier, France
- Laboratoire Charles Coulomb, CNRS UMR 5221, Université de Montpellier, Montpellier, France
- Département d'Imagerie Médicale, Centre Hospitalier Universitaire Caremeau, Nîmes, France
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Staffaroni AM, Elahi FM, McDermott D, Marton K, Karageorgiou E, Sacco S, Paoletti M, Caverzasi E, Hess CP, Rosen HJ, Geschwind MD. Neuroimaging in Dementia. Semin Neurol 2017; 37:510-537. [PMID: 29207412 PMCID: PMC5823524 DOI: 10.1055/s-0037-1608808] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Although the diagnosis of dementia still is primarily based on clinical criteria, neuroimaging is playing an increasingly important role. This is in large part due to advances in techniques that can assist with discriminating between different syndromes. Magnetic resonance imaging remains at the core of differential diagnosis, with specific patterns of cortical and subcortical changes having diagnostic significance. Recent developments in molecular PET imaging techniques have opened the door for not only antemortem but early, even preclinical, diagnosis of underlying pathology. This is vital, as treatment trials are underway for pharmacological agents with specific molecular targets, and numerous failed trials suggest that earlier treatment is needed. This article provides an overview of classic neuroimaging findings as well as new and cutting-edge research techniques that assist with clinical diagnosis of a range of dementia syndromes, with an emphasis on studies using pathologically proven cases.
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Affiliation(s)
- Adam M. Staffaroni
- Department of Neurology, Memory and Aging Center, University of California, San Francisco (UCSF), San Francisco, California
| | - Fanny M. Elahi
- Department of Neurology, Memory and Aging Center, University of California, San Francisco (UCSF), San Francisco, California
| | - Dana McDermott
- Department of Neurology, Memory and Aging Center, University of California, San Francisco (UCSF), San Francisco, California
| | - Kacey Marton
- Department of Neurology, Memory and Aging Center, University of California, San Francisco (UCSF), San Francisco, California
| | - Elissaios Karageorgiou
- Department of Neurology, Memory and Aging Center, University of California, San Francisco (UCSF), San Francisco, California
- Neurological Institute of Athens, Athens, Greece
| | - Simone Sacco
- Department of Neurology, Memory and Aging Center, University of California, San Francisco (UCSF), San Francisco, California
- Institute of Radiology, Department of Clinical Surgical Diagnostic and Pediatric Sciences, University of Pavia, Pavia, Italy
| | - Matteo Paoletti
- Department of Neurology, Memory and Aging Center, University of California, San Francisco (UCSF), San Francisco, California
- Institute of Radiology, Department of Clinical Surgical Diagnostic and Pediatric Sciences, University of Pavia, Pavia, Italy
| | - Eduardo Caverzasi
- Department of Neurology, Memory and Aging Center, University of California, San Francisco (UCSF), San Francisco, California
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
| | - Christopher P. Hess
- Division of Neuroradiology, Department of Radiology, University of California, San Francisco (UCSF), California
| | - Howard J. Rosen
- Department of Neurology, Memory and Aging Center, University of California, San Francisco (UCSF), San Francisco, California
| | - Michael D. Geschwind
- Department of Neurology, Memory and Aging Center, University of California, San Francisco (UCSF), San Francisco, California
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Mao D, Li Y, Liu P, Peng SL, Pillai JJ, Lu H. Three-dimensional mapping of brain venous oxygenation using R2* oximetry. Magn Reson Med 2017; 79:1304-1313. [PMID: 28585238 DOI: 10.1002/mrm.26763] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Revised: 04/07/2017] [Accepted: 05/03/2017] [Indexed: 11/11/2022]
Abstract
PURPOSE Cerebral venous oxygenation (Yv ) is an important biomarker for brain diseases. This study aims to develop an R2*-based MR oximetry that can measure cerebral Yv in 3D. METHODS This technique separates blood signal from tissue by velocity-encoding phase contrast and measures the R2* of pure blood by multi-gradient-echo acquisition. The blood R2* was converted to Yv using an R2*-versus-oxygenation (Y) calibration curve, which was obtained by in vitro bovine blood experiments. Reproducibility, sensitivity, validity, and resolution dependence of the technique were evaluated. RESULTS In vitro R2*-Y calibration plot revealed a strong dependence of blood R2* on oxygenation, with additional dependence on hematocrit. In vivo results demonstrated that the technique can provide a 3D venous oxygenation map that depicts both large sinuses and smaller cortical veins, with venous oxygenation ranging from 57 to 72%. Intrasession coefficient of variation of the measurement was 3.0%. The technique detected an average Yv increase of 10.8% as a result of hyperoxia, which was validated by global oxygenation measurement from T2 -Relaxation-Under-Spin-Tagging (TRUST) MRI. Two spatial resolutions, one with an isotropic voxel dimension and the other with a nonisotropic dimension, were tested for full brain coverage. CONCLUSIONS This study demonstrated the feasibility of 3D brain oxygenation mapping without using contrast agent. Magn Reson Med 79:1304-1313, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Deng Mao
- The Russell H. Morgan Department of Radiology & Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,Graduate School of Biomedical Sciences, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Yang Li
- The Russell H. Morgan Department of Radiology & Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,Graduate School of Biomedical Sciences, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Peiying Liu
- The Russell H. Morgan Department of Radiology & Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Shin-Lei Peng
- The Russell H. Morgan Department of Radiology & Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,Department of Biomedical Imaging and Radiological Science, China Medical University, Taichung, Taiwan
| | - Jay J Pillai
- The Russell H. Morgan Department of Radiology & Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Hanzhang Lu
- The Russell H. Morgan Department of Radiology & Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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Sheng M, Liu P, Mao D, Ge Y, Lu H. The impact of hyperoxia on brain activity: A resting-state and task-evoked electroencephalography (EEG) study. PLoS One 2017; 12:e0176610. [PMID: 28464001 PMCID: PMC5412995 DOI: 10.1371/journal.pone.0176610] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Accepted: 04/13/2017] [Indexed: 12/17/2022] Open
Abstract
A better understanding of the effect of oxygen on brain electrophysiological activity may provide a more mechanistic insight into clinical studies that use oxygen treatment in pathological conditions, as well as in studies that use oxygen to calibrate functional magnetic resonance imaging (fMRI) signals. This study applied electroencephalography (EEG) in healthy subjects and investigated how high a concentration of oxygen in inhaled air (i.e., normobaric hyperoxia) alters brain activity under resting-state and task-evoked conditions. Study 1 investigated its impact on resting EEG and revealed that hyperoxia suppressed α (8-13Hz) and β (14-35Hz) band power (by 15.6±2.3% and 14.1±3.1%, respectively), but did not change the δ (1-3Hz), θ (4-7Hz), and γ (36-75Hz) bands. Sham control experiments did not result in such changes. Study 2 reproduced these findings, and, furthermore, examined the effect of hyperoxia on visual stimulation event-related potentials (ERP). It was found that the main peaks of visual ERP, specifically N1 and P2, were both delayed during hyperoxia compared to normoxia (P = 0.04 and 0.02, respectively). In contrast, the amplitude of the peaks did not show a change. Our results suggest that hyperoxia has a pronounced effect on brain neural activity, for both resting-state and task-evoked potentials.
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Affiliation(s)
- Min Sheng
- Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Peiying Liu
- Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Deng Mao
- Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Yulin Ge
- Department of Radiology, New York University Langone Medical Center, New York, New York, United States of America
| | - Hanzhang Lu
- Advanced Imaging Research Center, The University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- * E-mail:
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Thomas BP, Sheng M, Tseng BY, Tarumi T, Martin-Cook K, Womack KB, Cullum MC, Levine BD, Zhang R, Lu H. Reduced global brain metabolism but maintained vascular function in amnestic mild cognitive impairment. J Cereb Blood Flow Metab 2017; 37:1508-1516. [PMID: 27389176 PMCID: PMC5453471 DOI: 10.1177/0271678x16658662] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Amnestic mild cognitive impairment represents an early stage of Alzheimer's disease, and characterization of physiological alterations in mild cognitive impairment is an important step toward accurate diagnosis and intervention of this condition. To investigate the extent of neurodegeneration in patients with mild cognitive impairment, whole-brain cerebral metabolic rate of oxygen in absolute units of µmol O2/min/100 g was quantified in 44 amnestic mild cognitive impairment and 28 elderly controls using a novel, non-invasive magnetic resonance imaging method. We found a 12.9% reduction ( p = 0.004) in cerebral metabolic rate of oxygen in mild cognitive impairment, which was primarily attributed to a reduction in the oxygen extraction fraction, by 10% ( p = 0.016). Global cerebral blood flow was not found to be different between groups. Another aspect of vascular function, cerebrovascular reactivity, was measured by CO2-inhalation magnetic resonance imaging and was found to be equivalent between groups. Therefore, there seems to be a global, diffuse diminishment in neural function in mild cognitive impairment, while their vascular function did not show a significant reduction.
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Affiliation(s)
- Binu P Thomas
- 1 Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Min Sheng
- 1 Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Benjamin Y Tseng
- 2 Institute of Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas, TX, USA
| | - Takashi Tarumi
- 2 Institute of Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas, TX, USA
| | - Kristen Martin-Cook
- 3 Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Kyle B Womack
- 3 Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Munro C Cullum
- 3 Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, Dallas, TX, USA.,4 Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Benjamin D Levine
- 2 Institute of Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas, TX, USA
| | - Rong Zhang
- 2 Institute of Exercise and Environmental Medicine, Texas Health Presbyterian Hospital, Dallas, TX, USA.,3 Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Hanzhang Lu
- 1 Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, USA.,5 Department of Radiology, Johns Hopkins University, Baltimore, MD, USA
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Huang L, Liu Y, Lu J, Cerqueira B, Misra V, Duong TQ. Intraarterial transplantation of human umbilical cord blood mononuclear cells in hyperacute stroke improves vascular function. Stem Cell Res Ther 2017; 8:74. [PMID: 28330501 PMCID: PMC5361847 DOI: 10.1186/s13287-017-0529-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 01/18/2017] [Accepted: 03/04/2017] [Indexed: 12/20/2022] Open
Abstract
Background Human umbilical cord blood (hUCB) cell therapy is a promising treatment for ischemic stroke. The effects of hyperacute stem cell transplantation on cerebrovascular function in ischemic stroke are, however, not well understood. This study evaluated the effects of hyperacute intraarterial transplantation of hUCB mononuclear cells (MNCs) on cerebrovascular function in stroke rats using serial magnetic resonance imaging (MRI). Methods HUCB MNCs or vehicle were administered to stroke rats via the internal carotid artery immediately after reperfusion at 60 min following ischemia onset. Lesion volumes were longitudinally evaluated by MRI on days 0, 2, 14, and 28 after stroke, accompanied by behavioral tests. Cerebral blood flow (CBF) and cerebrovascular reactivity were measured by perfusion MRI and CO2 functional MRI (fMRI) at 28 days post-stroke; corresponding vascular morphological changes were also detected by immunohistology in the same animals. Results We found that CBF to the stroke-affected region at 28 days was improved (normalized CBF value: 1.41 ± 0.30 versus 0.49 ± 0.07) by intraarterial transplantation of hUCB MNCs in the hyperacute stroke phase, compared to vehicle control. Cerebrovascular reactivity within the stroke-affected area, measured by CBF fMRI, was also increased (35.2 ± 3.5% versus 12.8 ± 4.3%), as well as the corresponding cerebrovascular density. Some engrafted cells appeared with microvascular-like morphology and stained positive for von Willebrand Factor (an endothelial cell marker), suggesting they differentiated into endothelial cells. Some engrafted cells also connected to host endothelial cells, suggesting they interacted with the host vasculature. Compared to the vehicle group, infarct volume at 28 days in the stem cell treated group was significantly smaller (160.9 ± 15.7 versus 231.2 ± 16.0 mm3); behavioral deficits were also markedly reduced by stem cell treatment at day 28 (19.5 ± 1.0% versus 30.7 ± 4.7% on the foot fault test; 68.2 ± 4.6% versus 86.6 ± 5.8% on the cylinder test). More tissue within initial perfusion-diffusion mismatch was rescued in the treatment group. Conclusions Intraarterial hUCB MNC transplantation during the hyperacute phase of ischemic stroke improved cerebrovascular function and reduced behavioral deficits and infarct volume.
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Affiliation(s)
- Lei Huang
- Research Imaging Institute, University of Texas Health Science Center, San Antonio, Texas, USA
| | - Yichu Liu
- Department of Biomedical Engineering, University of Texas, San Antonio, Texas, USA
| | - Jianfei Lu
- Research Imaging Institute, University of Texas Health Science Center, San Antonio, Texas, USA
| | - Bianca Cerqueira
- Research Imaging Institute, University of Texas Health Science Center, San Antonio, Texas, USA.,Department of Biomedical Engineering, University of Texas, San Antonio, Texas, USA
| | - Vivek Misra
- Department of Neurology, University of Texas Health Science Center, San Antonio, Texas, USA
| | - Timothy Q Duong
- Research Imaging Institute, University of Texas Health Science Center, San Antonio, Texas, USA. .,Radiology, Stony Brook Medicine, Stony Brook, NY, USA.
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Cogswell PM, Davis TL, Strother MK, Faraco CC, Scott AO, Jordan LC, Fusco MR, Frederick BD, Hendrikse J, Donahue MJ. Impact of vessel wall lesions and vascular stenoses on cerebrovascular reactivity in patients with intracranial stenotic disease. J Magn Reson Imaging 2017; 46:1167-1176. [PMID: 28061015 DOI: 10.1002/jmri.25602] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 12/06/2016] [Indexed: 11/10/2022] Open
Abstract
PURPOSE To compare cerebrovascular reactivity (CVR) and CVR lagtimes in flow territories perfused by vessels with vs. without proximal arterial wall disease and/or stenosis, separately in patients with atherosclerotic and nonatherosclerotic (moyamoya) intracranial stenosis. MATERIALS AND METHODS Atherosclerotic and moyamoya patients with >50% intracranial stenosis and <70% cervical stenosis underwent angiography, vessel wall imaging (VWI), and CVR-weighted imaging (n = 36; vessel segments evaluated = 396). Angiography and VWI were evaluated for stenosis locations and vessel wall lesions. Maximum CVR and CVR lagtime were contrasted between vascular territories with and without proximal intracranial vessel wall lesions and stenosis, and a Wilcoxon rank-sum was test used to determine differences (criteria: corrected two-sided P < 0.05). RESULTS CVR lagtime was prolonged in territories with vs. without a proximal vessel wall lesion or stenosis for both patient groups: moyamoya (CVR lagtime = 45.5 sec ± 14.2 sec vs. 35.7 sec ± 9.7 sec, P < 0.001) and atherosclerosis (CVR lagtime = 38.2 sec ± 9.1 sec vs. 35.0 sec ± 7.2 sec, P = 0.001). For reactivity, a significant decrease in maximum CVR in the moyamoya group only (maximum CVR = 9.8 ± 2.2 vs. 12.0 ± 2.4, P < 0.001) was observed. CONCLUSION Arterial vessel wall lesions detected on noninvasive, noncontrast intracranial VWI in patients with intracranial stenosis correlate on average with tissue-level impairment on CVR-weighted imaging. LEVEL OF EVIDENCE 4 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2017;46:1167-1176.
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Affiliation(s)
- Petrice M Cogswell
- Department of Radiology, Vanderbilt University, Nashville, Tennessee, USA
| | - Taylor L Davis
- Department of Radiology, Vanderbilt University, Nashville, Tennessee, USA
| | | | - Carlos C Faraco
- Department of Radiology, Vanderbilt University, Nashville, Tennessee, USA
| | - Allison O Scott
- Department of Radiology, Vanderbilt University, Nashville, Tennessee, USA
| | - Lori C Jordan
- Department of Pediatrics, Vanderbilt University, Nashville, Tennessee, USA.,Department of Neurology, Vanderbilt University, Nashville, Tennessee, USA
| | - Matthew R Fusco
- Department of Neurosurgery, Vanderbilt University, Nashville, Tennessee, USA
| | | | - Jeroen Hendrikse
- Department of Radiology, University Medical Center Utrecht, Utrecht, Netherlands
| | - Manus J Donahue
- Department of Radiology, Vanderbilt University, Nashville, Tennessee, USA.,Department of Neurology, Vanderbilt University, Nashville, Tennessee, USA.,Department of Psychiatry, Vanderbilt University, Nashville, Tennessee, USA
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Cerebrovascular reactivity mapping without gas challenges. Neuroimage 2016; 146:320-326. [PMID: 27888058 DOI: 10.1016/j.neuroimage.2016.11.054] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 11/16/2016] [Accepted: 11/21/2016] [Indexed: 11/22/2022] Open
Abstract
Cerebrovascular reactivity (CVR), the ability of cerebral vessels to dilate or constrict, has been shown to provide valuable information in the diagnosis and treatment evaluation of patients with various cerebrovascular conditions. CVR mapping is typically performed using hypercapnic gas inhalation as a vasoactive challenge while collecting BOLD images, but the inherent need of gas inhalation and the associated apparatus setup present a practical obstacle in applying it in routine clinical use. Therefore, we aimed to develop a new method to map CVR using resting-state BOLD data without the need of gas inhalation. This approach exploits the natural variation in respiration and measures its influence on BOLD MRI signal. In this work, we first identified a surrogate of the arterial CO2 fluctuation during spontaneous breathing from the global BOLD signal. Second, we tested the feasibility and reproducibility of the proposed approach to use the above-mentioned surrogate as a regressor to estimate voxel-wise CVR. Third, we validated the "resting-state CVR map" with a conventional CVR map obtained with hypercapnic gas inhalation in healthy volunteers. Finally, we tested the utility of this new approach in detecting abnormal CVR in a group of patients with Moyamoya disease, and again validated the results using the conventional gas inhalation method. Our results showed that global BOLD signal fluctuation in the frequency range of 0.02-0.04Hz contains the most prominent contribution from natural variation in arterial CO2. The CVR map calculated using this signal as a regressor is reproducible across runs (ICC=0.91±0.06), and manifests a strong spatial correlation with results measured with a conventional hypercapnia-based method in healthy subjects (r=0.88, p<0.001). We also found that resting-state CVR was able to identify vasodilatory deficit in patients with steno-occlusive disease, the spatial pattern of which matches that obtained using the conventional gas method (r=0.71±0.18). These results suggest that CVR obtained with resting-state BOLD may be a useful alternative in detecting vascular deficits in clinical applications when gas challenge is not feasible.
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Ravi H, Liu P, Peng SL, Liu H, Lu H. Simultaneous multi-slice (SMS) acquisition enhances the sensitivity of hemodynamic mapping using gas challenges. NMR IN BIOMEDICINE 2016; 29:1511-1518. [PMID: 27598821 PMCID: PMC5123823 DOI: 10.1002/nbm.3600] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Revised: 06/29/2016] [Accepted: 07/18/2016] [Indexed: 06/06/2023]
Abstract
Hemodynamic mapping using gas inhalation has received increasing interest in recent years. Cerebrovascular reactivity (CVR), which reflects the ability of the brain vasculature to dilate in response to a vasoactive stimulus, can be measured by CO2 inhalation with continuous acquisition of blood oxygen level-dependent (BOLD) magnetic resonance images. Cerebral blood volume (CBV) can be measured by O2 inhalation. These hemodynamic mapping methods are appealing because of their absence of gadolinium contrast agent, their ability to assess both baseline perfusion and vascular reserve, and their utility in calibrating the functional magnetic resonance imaging (fMRI) signal. However, like other functional and physiological indices, a major drawback of these measurements is their poor sensitivity and reliability. Simultaneous multi-slice echo planar imaging (SMS EPI) is a fast imaging technology that allows the excitation and acquisition of multiple two-dimensional slices simultaneously, and has been shown to enhance the sensitivity of several MRI applications. To our knowledge, the benefit of SMS in gas inhalation imaging has not been investigated. In this work, we compared the sensitivity of CO2 and O2 inhalation data collected using SMS factor 2 (SMS2) and SMS factor 3 (SMS3) with those collected using conventional EPI (SMS1). We showed that the sensitivity of SMS scans was significantly (p = 0.01) higher than that of conventional EPI, although no difference was found between SMS2 and SMS3 (p = 0.3). On a voxel-wise level, approximately 20-30% of voxels in the brain showed a significant enhancement in sensitivity when using SMS compared with conventional EPI, with other voxels showing an increase, but not reaching statistical significance. When using SMS, the scan duration can be reduced by half, whilst maintaining the sensitivity of conventional EPI. The availability of a sensitive acquisition technique can further enhance the potential of gas inhalation MRI in clinical applications.
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Affiliation(s)
- Harshan Ravi
- Department of Radiology, Johns Hopkins University, Baltimore, MD, USA
- Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, TX, USA
- Department of Bioengineering, University of Texas at Arlington, Arlington, TX, USA
| | - Peiying Liu
- Department of Radiology, Johns Hopkins University, Baltimore, MD, USA
- Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, TX, USA
| | - Shin-Lei Peng
- Department of Radiology, Johns Hopkins University, Baltimore, MD, USA
- Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, TX, USA
- Department of Biomedical Imaging and Radiological Science, China Medical University, Taichung, Taiwan
| | - Hanli Liu
- Department of Bioengineering, University of Texas at Arlington, Arlington, TX, USA
| | - Hanzhang Lu
- Department of Radiology, Johns Hopkins University, Baltimore, MD, USA.
- Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, TX, USA.
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Donahue MJ, Strother MK, Lindsey KP, Hocke LM, Tong Y, Frederick BD. Time delay processing of hypercapnic fMRI allows quantitative parameterization of cerebrovascular reactivity and blood flow delays. J Cereb Blood Flow Metab 2016; 36:1767-1779. [PMID: 26661192 PMCID: PMC5076782 DOI: 10.1177/0271678x15608643] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 07/29/2015] [Indexed: 11/17/2022]
Abstract
Blood oxygenation level-dependent fMRI contrast depends on the volume and oxygenation of blood flowing through the circulatory system. The effects on image intensity depend temporally on the arrival of blood within a voxel, and signal can be monitored during the time course of such blood flow. It has been previously shown that the passage of global endogenous variations in blood volume and oxygenation can be tracked as blood passes through the brain by determining the strength and peak time lag of their cross-correlation with blood oxygenation level-dependent data. By manipulating blood composition using transient hypercarbia and hyperoxia, we can induce much larger oxygenation and volume changes in the blood oxygenation level-dependent signal than result from natural endogenous fluctuations. This technique was used to examine cerebrovascular parameters in healthy subjects (n = 8) and subjects with intracranial stenosis (n = 22), with a subgroup of intracranial stenosis subjects scanned before and after surgical revascularization (n = 6). The halfwidth of cross-correlation lag times in the brain was larger in IC stenosis subjects (21.21 ± 14.22 s) than in healthy control subjects (8.03 ± 3.67), p < 0.001, and was subsequently reduced in regions that co-localized with surgical revascularization. These data show that blood circulatory timing can be measured robustly and longitudinally throughout the brain using simple respiratory challenges.
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Affiliation(s)
- Manus J Donahue
- Department of Radiology, Vanderbilt Medical Center, Nashville, TN, USA Department of Neurology, Vanderbilt Medical Center, Nashville, TN, USA Department of Psychiatry, Vanderbilt Medical Center, Nashville, TN, USA Department of Physics and Astronomy, Vanderbilt University, Nashville, TN, USA
| | - Megan K Strother
- Department of Radiology, Vanderbilt Medical Center, Nashville, TN, USA
| | - Kimberly P Lindsey
- Brain Imaging Center, McLean Hospital, Belmont, MA, USA Department of Psychiatry, Harvard Medical School, Boston, MA, USA
| | - Lia M Hocke
- Brain Imaging Center, McLean Hospital, Belmont, MA, USA Department of Bioengineering, Tufts University, Medford, MA, USA
| | - Yunjie Tong
- Brain Imaging Center, McLean Hospital, Belmont, MA, USA Department of Psychiatry, Harvard Medical School, Boston, MA, USA
| | - Blaise deB Frederick
- Brain Imaging Center, McLean Hospital, Belmont, MA, USA Department of Psychiatry, Harvard Medical School, Boston, MA, USA
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Liu P, Welch BG, Li Y, Gu H, King D, Yang Y, Pinho M, Lu H. Multiparametric imaging of brain hemodynamics and function using gas-inhalation MRI. Neuroimage 2016; 146:715-723. [PMID: 27693197 DOI: 10.1016/j.neuroimage.2016.09.063] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Revised: 09/21/2016] [Accepted: 09/26/2016] [Indexed: 12/30/2022] Open
Abstract
Diagnosis and treatment monitoring of cerebrovascular diseases routinely require hemodynamic imaging of the brain. Current methods either only provide part of the desired information or require the injection of multiple exogenous agents. In this study, we developed a multiparametric imaging scheme for the imaging of brain hemodynamics and function using gas-inhalation MRI. The proposed technique uses a single MRI scan to provide simultaneous measurements of baseline venous cerebral blood volume (vCBV), cerebrovascular reactivity (CVR), bolus arrival time (BAT), and resting-state functional connectivity (fcMRI). This was achieved with a novel, concomitant O2 and CO2 gas inhalation paradigm, rapid MRI image acquisition with a 9.3min BOLD sequence, and an advanced algorithm to extract multiple hemodynamic information from the same dataset. In healthy subjects, CVR and vCBV values were 0.23±0.03%/mmHg and 0.0056±0.0006%/mmHg, respectively, with a strong correlation (r=0.96 for CVR and r=0.91 for vCBV) with more conventional, separate acquisitions that take twice the scan time. In patients with Moyamoya syndrome, CVR in the stenosis-affected flow territories (typically anterior-cerebral-artery, ACA, and middle-cerebral-artery, MCA, territories) was significantly lower than that in posterior-cerebral-artery (PCA), which typically has minimal stenosis, flow territories (0.12±0.06%/mmHg vs. 0.21±0.05%/mmHg, p<0.001). BAT of the gas bolus was significantly longer (p=0.008) in ACA/MCA territories, compared to PCA, and the maps were consistent with the conventional contrast-enhanced CT perfusion method. FcMRI networks were robustly identified from the gas-inhalation MRI data after factoring out the influence of CO2 and O2 on the signal time course. The spatial correspondence between the gas-data-derived fcMRI maps and those using a separate, conventional fcMRI scan was excellent, showing a spatial correlation of 0.58±0.17 and 0.64±0.20 for default mode network and primary visual network, respectively. These findings suggest that advanced gas-inhalation MRI provides reliable measurements of multiple hemodynamic parameters within a clinically acceptable imaging time and is suitable for patient examinations.
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Affiliation(s)
- Peiying Liu
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, United States
| | - Babu G Welch
- Department of Neurological Surgery, UT Southwestern Medical Center, Dallas, TX 75390, United States; Department of Radiology, UT Southwestern Medical Center, Dallas, TX 75390, United States
| | - Yang Li
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, United States; Biomedical Engineering Graduate Program, UT Southwestern Medical Center, Dallas, TX 75390, United States
| | - Hong Gu
- Neuroimaging Research Branch, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, United States
| | - Darlene King
- Department of Neurological Surgery, UT Southwestern Medical Center, Dallas, TX 75390, United States
| | - Yihong Yang
- Neuroimaging Research Branch, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, United States
| | - Marco Pinho
- Department of Radiology, UT Southwestern Medical Center, Dallas, TX 75390, United States
| | - Hanzhang Lu
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, United States.
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Fisher JA. The CO2 stimulus for cerebrovascular reactivity: Fixing inspired concentrations vs. targeting end-tidal partial pressures. J Cereb Blood Flow Metab 2016; 36:1004-11. [PMID: 27000209 PMCID: PMC4908627 DOI: 10.1177/0271678x16639326] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Accepted: 02/20/2016] [Indexed: 11/15/2022]
Abstract
Cerebrovascular reactivity (CVR) studies have elucidated the physiology and pathophysiology of cerebral blood flow regulation. A non-invasive, high spatial resolution approach uses carbon dioxide (CO2) as the vasoactive stimulus and magnetic resonance techniques to estimate the cerebral blood flow response. CVR is assessed as the ratio response change to stimulus change. Precise control of the stimulus is sought to minimize CVR variability between tests, and show functional differences. Computerized methods targeting end-tidal CO2 partial pressures are precise, but expensive. Simpler, improvised methods that fix the inspired CO2 concentrations have been recommended as less expensive, and so more widely accessible. However, these methods have drawbacks that have not been previously presented by those that advocate their use, or those that employ them in their studies. As one of the developers of a computerized method, I provide my perspective on the trade-offs between these two methods. The main concern is that declaring the precision of fixed inspired concentration of CO2 is misleading: it does not, as implied, translate to precise control of the actual vasoactive stimulus - the arterial partial pressure of CO2 The inherent test-to-test, and therefore subject-to-subject variability, precludes clinical application of findings. Moreover, improvised methods imply widespread duplication of development, assembly time and costs, yet lack uniformity and quality control. A tabular comparison between approaches is provided.
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Affiliation(s)
- Joseph A Fisher
- Department of Anesthesiology University Health Network, and Department of Physiology, University of Toronto, Toronto, Canada
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Song Z, McDonough IM, Liu P, Lu H, Park DC. Cortical amyloid burden and age moderate hippocampal activity in cognitively-normal adults. NEUROIMAGE-CLINICAL 2016; 12:78-84. [PMID: 27408792 PMCID: PMC4925884 DOI: 10.1016/j.nicl.2016.05.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Revised: 05/08/2016] [Accepted: 05/25/2016] [Indexed: 11/30/2022]
Abstract
Neurodegeneration in the medial temporal lobe, particularly in the hippocampus, is viewed as the primary source of AD-related memory deficits. Yet, in the earliest preclinical phase of Alzheimer's disease (AD), amyloid-beta (Aβ) plaques deposit primarily in the neocortex, not in the medial temporal lobe. Tau tangles, however, do often aggregate in the medial temporal lobe in parallel with amyloid deposition in the neocortex in AD. In the present study, we focused on the relationship between cortical amyloid deposition and hippocampal activity during a memory-encoding task in a sample of cognitively-normal elderly aged 60–89. We hypothesized that age would moderate the Aβ effect on hippocampal activity, and could explain some of the mixed findings in the literature. We report that high cortical Aβ load was associated with lower task-related hippocampal activity during memory encoding. Importantly, this relationship was found more evident in the younger elderly, even after controlling for subsequent recognition memory of the in-scanner task and a general episodic memory construct score. Furthermore, regional cerebrovascular reactivity measured in a subset of participants showed little role in modifying the age-dependent Aβ effect on hippocampal activity. Our findings support the idea that age is an important variable in understanding hippocampal function in preclinical AD.
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Affiliation(s)
- Zhuang Song
- Center for Vital Longevity, University of Texas at Dallas, Dallas, TX 75235, USA
- Corresponding author.
| | - Ian M. McDonough
- Center for Vital Longevity, University of Texas at Dallas, Dallas, TX 75235, USA
| | - Peiying Liu
- Department of Radiology & Radiological Science, Johns Hopkins University, MD 21287, USA
| | - Hanzhang Lu
- Department of Radiology & Radiological Science, Johns Hopkins University, MD 21287, USA
| | - Denise C. Park
- Center for Vital Longevity, University of Texas at Dallas, Dallas, TX 75235, USA
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Marshall O, Uh J, Lurie D, Lu H, Milham MP, Ge Y. The influence of mild carbon dioxide on brain functional homotopy using resting-state fMRI. Hum Brain Mapp 2015; 36:3912-21. [PMID: 26138728 PMCID: PMC6320689 DOI: 10.1002/hbm.22886] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Revised: 06/09/2015] [Accepted: 06/16/2015] [Indexed: 11/10/2022] Open
Abstract
Homotopy reflects the intrinsic functional architecture of the brain through synchronized spontaneous activity between corresponding bilateral regions, measured as voxel mirrored homotopic connectivity (VMHC). Hypercapnia is known to have clear impact on brain hemodynamics through vasodilation, but have unclear effect on neuronal activity. This study investigates the effect of hypercapnia on brain homotopy, achieved by breathing 5% carbon dioxide (CO2 ) gas mixture. A total of 14 healthy volunteers completed three resting state functional MRI (RS-fMRI) scans, the first and third under normocapnia and the second under hypercapnia. VMHC measures were calculated as the correlation between the BOLD signal of each voxel and its counterpart in the opposite hemisphere. Group analysis was performed between the hypercapnic and normocapnic VMHC maps. VMHC showed a diffused decrease in response to hypercapnia. Significant regional decreases in VMHC were observed in all anatomical lobes, except for the occipital lobe, in the following functional hierarchical subdivisions: the primary sensory-motor, unimodal, heteromodal, paralimbic, as well as in the following functional networks: ventral attention, somatomotor, default frontoparietal, and dorsal attention. Our observation that brain homotopy in RS-fMRI is affected by arterial CO2 levels suggests that caution should be used when comparing RS-fMRI data between healthy controls and patients with pulmonary diseases and unusual respiratory patterns such as sleep apnea or chronic obstructive pulmonary disease.
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Affiliation(s)
- Olga Marshall
- Radiology/Center for Biomedical ImagingNew York University School of MedicineNew YorkNew York
| | - Jinsoo Uh
- Advanced Imaging Research CenterUniversity of Texas Southwestern Medical CenterDallasTexas
| | - Daniel Lurie
- Center for the Developing Brain, Child Mind InstituteNew YorkNew York
| | - Hanzhang Lu
- Advanced Imaging Research CenterUniversity of Texas Southwestern Medical CenterDallasTexas
- Department of RadiologyJohns Hopkins University School of MedicineBaltimoreMaryland
| | - Michael P. Milham
- Center for the Developing Brain, Child Mind InstituteNew YorkNew York
- Nathan S Kline Institute for Psychiatric ResearchNew York
| | - Yulin Ge
- Radiology/Center for Biomedical ImagingNew York University School of MedicineNew YorkNew York
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Ravi H, Thomas BP, Peng SL, Liu H, Lu H. On the optimization of imaging protocol for the mapping of cerebrovascular reactivity. J Magn Reson Imaging 2015; 43:661-8. [PMID: 26268541 DOI: 10.1002/jmri.25028] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2015] [Revised: 07/23/2015] [Accepted: 07/24/2015] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND To devise an improved blood-oxygen-level-dependent (BOLD) imaging protocol for cerebrovascular reactivity (CVR) measurement that can remove a known artifact of negative values. METHODS Theoretical and simulation studies were first performed to understand the biophysical mechanism of the negative CVR signals, through which improved BOLD sequence parameters were proposed. This was achieved by equating signal intensities between cerebrospinal fluid and blood, by means of shortening the echo time (TE) of the BOLD sequence. Then, 10 healthy volunteers were recruited to participate in an experimental study, in which we compared the CVR results of two versions of the optimized ("Opt1" and "Opt2") protocols with that of the standard protocol at 3 Tesla. Two sessions were performed for each subject to test the reproducibility of all three protocols. RESULTS Experimental results demonstrated that the optimized protocols resulted in elimination of negative-CVR voxels. Quantitative CVR results were compared across protocols, which show that the optimized protocols yielded smaller CVR values (Opt1: 0.16 ± 0.01 %BOLD/mmHg CO2 ; Opt2: 0.15 ± 0.01 %BOLD/mmHg CO2 ) than (P < 0.001) the standard protocol (0.21 ± 0.01 %BOLD/mmHg CO2 ), but the CNR was comparable (P = 0.1) to the standard protocol. The coefficient-of-variation between repetitions was found to be 5.6 ± 1.4%, 6.3 ± 1.6%, and 6.9 ± 0.9% for the three protocols, but there were no significant differences (P = 0.65). CONCLUSION Based on the theoretical and experimental results obtained from this study, we suggest that the use of a TE shorter than those used in fMRI is necessary to minimize negative artifact in CVR results.
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Affiliation(s)
- Harshan Ravi
- Department of Radiology, Johns Hopkins University, Baltimore, Maryland, USA
- Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, Texas, USA
- Department of Bioengineering, University of Texas at Arlington, Arlington, Texas, USA
| | - Binu P Thomas
- Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, Texas, USA
- Department of Bioengineering, University of Texas at Arlington, Arlington, Texas, USA
| | - Shin-Lei Peng
- Department of Radiology, Johns Hopkins University, Baltimore, Maryland, USA
- Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Hanli Liu
- Department of Bioengineering, University of Texas at Arlington, Arlington, Texas, USA
| | - Hanzhang Lu
- Department of Radiology, Johns Hopkins University, Baltimore, Maryland, USA
- Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, Texas, USA
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