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Lambers H, Wachsmuth L, Lippe C, Faber C. The impact of vasomotion on analysis of rodent fMRI data. Front Neurosci 2023; 17:1064000. [PMID: 36908777 PMCID: PMC9998505 DOI: 10.3389/fnins.2023.1064000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Accepted: 02/06/2023] [Indexed: 03/14/2023] Open
Abstract
Introduction Small animal fMRI is an essential part of translational research in the cognitive neurosciences. Due to small dimensions and animal physiology preclinical fMRI is prone to artifacts that may lead to misinterpretation of the data. To reach unbiased translational conclusions, it is, therefore, crucial to identify potential sources of experimental noise and to develop correction methods for contributions that cannot be avoided such as physiological noise. Aim of this study was to assess origin and prevalence of hemodynamic oscillations (HDO) in preclinical fMRI in rat, as well as their impact on data analysis. Methods Following the development of algorithms for HDO detection and suppression, HDO prevalence in fMRI measurements was investigated for different anesthetic regimens, comprising isoflurane and medetomidine, and for both gradient echo and spin echo fMRI sequences. In addition to assessing the effect of vasodilation on HDO, it was studied if HDO have a direct neuronal correlate using local field potential (LFP) recordings. Finally, the impact of HDO on analysis of fMRI data was assessed, studying both the impact on calculation of activation maps as well as the impact on brain network analysis. Overall, 303 fMRI measurements and 32 LFP recordings were performed in 71 rats. Results In total, 62% of the fMRI measurements showed HDO with a frequency of (0.20 ± 0.02) Hz. This frequent occurrence indicated that HDO cannot be generally neglected in fMRI experiments. Using the developed algorithms, HDO were detected with a specificity of 95%, and removed efficiently from the signal time courses. HDO occurred brain-wide under vasoconstrictive conditions in both small and large blood vessels. Vasodilation immediately interrupted HDO, which, however, returned within 1 h under vasoconstrictive conditions. No direct neuronal correlate of HDO was observed in LFP recordings. HDO significantly impacted analysis of fMRI data, leading to altered cluster sizes and F-values for activated voxels, as well as altered brain networks, when comparing data with and without HDO. Discussion We therefore conclude that HDO are caused by vasomotion under certain anesthetic conditions and should be corrected during fMRI data analysis to avoid bias.
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Affiliation(s)
| | - Lydia Wachsmuth
- Clinic of Radiology, University of Münster, Münster, Germany
| | - Chris Lippe
- Clinic of Radiology, University of Münster, Münster, Germany
| | - Cornelius Faber
- Clinic of Radiology, University of Münster, Münster, Germany
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Anderson GK, Rosenberg AJ, Barnes HJ, Bird J, Pentz B, Byman BRM, Jendzjowsky N, Wilson RJA, Day TA, Rickards CA. Peaks and valleys: oscillatory cerebral blood flow at high altitude protects cerebral tissue oxygenation. Physiol Meas 2021; 42:10.1088/1361-6579/ac0593. [PMID: 34038879 PMCID: PMC11046575 DOI: 10.1088/1361-6579/ac0593] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 05/26/2021] [Indexed: 01/21/2023]
Abstract
Introduction.Oscillatory patterns in arterial pressure and blood flow (at ∼0.1 Hz) may protect tissue oxygenation during conditions of reduced cerebral perfusion and/or hypoxia. We hypothesized that inducing oscillations in arterial pressure and cerebral blood flow at 0.1 Hz would protect cerebral blood flow and cerebral tissue oxygen saturation during exposure to a combination of simulated hemorrhage and sustained hypobaric hypoxia.Methods.Eight healthy human subjects (4 male, 4 female; 30.1 ± 7.6 year) participated in two experiments at high altitude (White Mountain, California, USA; altitude, 3800 m) following rapid ascent and 5-7 d of acclimatization: (1) static lower body negative pressure (LBNP, control condition) was used to induce central hypovolemia by reducing chamber pressure to -60 mmHg for 10 min(0 Hz), and; (2) oscillatory LBNP where chamber pressure was reduced to -60 mmHg, then oscillated every 5 s between -30 mmHg and -90 mmHg for 10 min(0.1 Hz). Measurements included arterial pressure, internal carotid artery (ICA) blood flow, middle cerebral artery velocity (MCAv), and cerebral tissue oxygen saturation (ScO2).Results.Forced 0.1 Hz oscillations in mean arterial pressure and mean MCAv were accompanied by a protection of ScO2(0.1 Hz: -0.67% ± 1.0%; 0 Hz: -4.07% ± 2.0%;P = 0.01). However, the 0.1 Hz profile did not protect against reductions in ICA blood flow (0.1 Hz: -32.5% ± 4.5%; 0 Hz: -19.9% ± 8.9%;P = 0.24) or mean MCAv (0.1 Hz: -18.5% ± 3.4%; 0 Hz: -15.3% ± 5.4%;P = 0.16).Conclusions.Induced oscillatory arterial pressure and cerebral blood flow led to protection of ScO2during combined simulated hemorrhage and sustained hypoxia. This protection was not associated with the preservation of cerebral blood flow suggesting preservation of ScO2may be due to mechanisms occurring within the microvasculature.
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Affiliation(s)
- Garen K Anderson
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, United States of America
- Co-first authorship
| | - Alexander J Rosenberg
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, United States of America
- Co-first authorship
| | - Haley J Barnes
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, United States of America
| | - Jordan Bird
- Department of Biology, Mount Royal University, Calgary, Alberta, Canada
| | - Brandon Pentz
- Department of Biology, Mount Royal University, Calgary, Alberta, Canada
| | - Britta R M Byman
- Department of Biology, Mount Royal University, Calgary, Alberta, Canada
| | - Nicholas Jendzjowsky
- Institute of Respiratory Medicine & Exercise Physiology, The Lundquist Institute at UCLA Harbor Medical, Torrance, CA, United States of America
| | - Richard J A Wilson
- Hotchkiss Brain Institute and Alberta Children’s Hospital Research Institute; Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
| | - Trevor A Day
- Department of Biology, Mount Royal University, Calgary, Alberta, Canada
| | - Caroline A Rickards
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, United States of America
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Kay VL, Sprick JD, Rickards CA. Cerebral oxygenation and regional cerebral perfusion responses with resistance breathing during central hypovolemia. Am J Physiol Regul Integr Comp Physiol 2017; 313:R132-R139. [PMID: 28539354 DOI: 10.1152/ajpregu.00385.2016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 04/21/2017] [Accepted: 05/11/2017] [Indexed: 11/22/2022]
Abstract
Resistance breathing improves tolerance to central hypovolemia induced by lower body negative pressure (LBNP), but this is not related to protection of anterior cerebral blood flow [indexed by mean middle cerebral artery velocity (MCAv)]. We hypothesized that inspiratory resistance breathing improves tolerance to central hypovolemia by maintaining cerebral oxygenation (ScO2), and protecting cerebral blood flow in the posterior cerebral circulation [indexed by posterior cerebral artery velocity (PCAv)]. Eight subjects (4 male/4 female) completed two experimental sessions of a presyncopal-limited LBNP protocol (3 mmHg/min onset rate) with and without (Control) resistance breathing via an impedance threshold device (ITD). ScO2 (via near-infrared spectroscopy), MCAv and PCAv (both via transcranial Doppler ultrasound), and arterial pressure (via finger photoplethysmography) were measured continuously. Hemodynamic responses were analyzed between the Control and ITD condition at baseline (T1) and the time representing 10 s before presyncope in the Control condition (T2). While breathing on the ITD increased LBNP tolerance from 1,506 ± 75 s to 1,704 ± 88 s (P = 0.003), both mean MCAv and mean PCAv were similar between conditions at T2 (P ≥ 0.46), and decreased by the same magnitude with and without ITD breathing (P ≥ 0.53). ScO2 also decreased by ~9% with or without ITD breathing at T2 (P = 0.97), and there were also no differences in deoxygenated (dHb) or oxygenated hemoglobin (HbO2) between conditions at T2 (P ≥ 0.43). There was no evidence that protection of regional cerebral blood velocity (i.e., anterior or posterior cerebral circulation) nor cerebral oxygen extraction played a key role in the determination of tolerance to central hypovolemia with resistance breathing.
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Affiliation(s)
- Victoria L Kay
- Institute for Cardiovascular and Metabolic Diseases, University of North Texas Health Science Center, Fort Worth, Texas
| | - Justin D Sprick
- Institute for Cardiovascular and Metabolic Diseases, University of North Texas Health Science Center, Fort Worth, Texas
| | - Caroline A Rickards
- Institute for Cardiovascular and Metabolic Diseases, University of North Texas Health Science Center, Fort Worth, Texas
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Tgavalekos KT, Kainerstorfer JM, Sassaroli A, Fantini S. Blood-pressure-induced oscillations of deoxy- and oxyhemoglobin concentrations are in-phase in the healthy breast and out-of-phase in the healthy brain. J Biomed Opt 2016; 21:101410. [PMID: 27020418 PMCID: PMC4809098 DOI: 10.1117/1.jbo.21.10.101410] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 03/03/2016] [Indexed: 05/29/2023]
Abstract
We present a near-infrared spectroscopy (NIRS) study of local hemodynamics in the breast and the brain (prefrontal cortex) of healthy volunteers in a protocol involving periodic perturbations to the systemic arterial blood pressure. These periodic perturbations were achieved by cyclic inflation (to a pressure of 200 mmHg) and deflation (at frequencies of 0.046, 0.056, 0.063, 0.071, and 0.083 Hz) of two pneumatic cuffs wrapped around the subject’s thighs. As a result of these systemic perturbations, the concentrations of deoxy- and oxyhemoglobin in tissue (D and O , respectively) oscillate at the set frequency. We found that the oscillations of D and O in breast tissue are in-phase at all frequencies considered, a result that we attribute to dominant contributions from blood volume oscillations. In contrast, D and O oscillations in brain tissue feature a frequency-dependent phase difference, which we attribute to significant contributions from cerebral blood flow oscillations. Frequency-resolved measurements of D and O oscillations are exploited by the technique of coherent hemodynamics spectroscopy for the assessment of cerebrovascular parameters and cerebral autoregulation. We show the relevant physiological information content of NIRS measurements of oscillatory hemodynamics, which have qualitatively distinct features in the healthy breast and healthy brain.
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Affiliation(s)
- Kristen T. Tgavalekos
- Tufts University, Department of Biomedical Engineering, 4 Colby Street, Medford, Massachusetts 02155, United States
| | - Jana M. Kainerstorfer
- Tufts University, Department of Biomedical Engineering, 4 Colby Street, Medford, Massachusetts 02155, United States
| | - Angelo Sassaroli
- Tufts University, Department of Biomedical Engineering, 4 Colby Street, Medford, Massachusetts 02155, United States
| | - Sergio Fantini
- Tufts University, Department of Biomedical Engineering, 4 Colby Street, Medford, Massachusetts 02155, United States
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Selb J, Yücel MA, Phillip D, Schytz HW, Iversen HK, Vangel M, Ashina M, Boas DA. Effect of motion artifacts and their correction on near-infrared spectroscopy oscillation data: a study in healthy subjects and stroke patients. J Biomed Opt 2015; 20:56011. [PMID: 26018790 PMCID: PMC4445402 DOI: 10.1117/1.jbo.20.5.056011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Accepted: 05/04/2015] [Indexed: 05/02/2023]
Abstract
Functional near-infrared spectroscopy is prone to contamination by motion artifacts (MAs). Motion correction algorithms have previously been proposed and their respective performance compared for evoked rain activation studies. We study instead the effect of MAs on "oscillation" data which is at the basis of functional connectivity and autoregulation studies. We use as our metric of interest the interhemispheric correlation (IHC), the correlation coefficient between symmetrical time series of oxyhemoglobin oscillations. We show that increased motion content results in a decreased IHC. Using a set of motion-free data on which we add real MAs, we find that the best motion correction approach consists of discarding the segments of MAs following a careful approach to minimize the contamination due to band-pass filtering of data from "bad" segments spreading into adjacent "good" segments. Finally, we compare the IHC in a stroke group and in a healthy group that we artificially contaminated with the MA content of the stroke group, in order to avoid the confounding effect of increased motion incidence in the stroke patients. After motion correction, the IHC remains lower in the stroke group in the frequency band around 0.1 and 0.04 Hz, suggesting a physiological origin for the difference. We emphasize the importance of considering MAs as a confounding factor in oscillation-based functional near-infrared spectroscopy studies.
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Affiliation(s)
- Juliette Selb
- Massachusetts General Hospital, Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, 149 13th Street, Charlestown, Massachusetts 02129, United States
- Address all correspondence to: Juliette Selb, E-mail:
| | - Meryem A. Yücel
- Massachusetts General Hospital, Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, 149 13th Street, Charlestown, Massachusetts 02129, United States
| | - Dorte Phillip
- University of Copenhagen, Rigshospitalet, Danish Headache Center, Faculty of Health Sciences, Department of Neurology, Copenhagen, Glostrup 2600, Denmark
| | - Henrik W. Schytz
- University of Copenhagen, Rigshospitalet, Danish Headache Center, Faculty of Health Sciences, Department of Neurology, Copenhagen, Glostrup 2600, Denmark
| | - Helle K. Iversen
- University of Copenhagen, Rigshospitalet, Stroke Unit, Faculty of Health Sciences, Department of Neurology, Copenhagen, Glostrup 2600, Denmark
| | - Mark Vangel
- Massachusetts General Hospital, Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, 149 13th Street, Charlestown, Massachusetts 02129, United States
| | - Messoud Ashina
- University of Copenhagen, Rigshospitalet, Danish Headache Center, Faculty of Health Sciences, Department of Neurology, Copenhagen, Glostrup 2600, Denmark
| | - David A. Boas
- Massachusetts General Hospital, Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, 149 13th Street, Charlestown, Massachusetts 02129, United States
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Abstract
Variability in arterial pressure and cerebral blood flow has traditionally been interpreted as a marker of cardiovascular decompensation, and has been associated with negative clinical outcomes across varying time scales, from impending orthostatic syncope to an increased risk of stroke. Emerging evidence, however, suggests that increased hemodynamic variability may, in fact, be protective in the face of acute challenges to perfusion, including significant central hypovolemia and hypotension (including hemorrhage), and during cardiac bypass surgery. This review presents the dichotomous views on the role of hemodynamic variability on clinical outcome, including the physiological mechanisms underlying these patterns, and the potential impact of increased and decreased variability on cerebral perfusion and oxygenation. We suggest that reconciliation of these two apparently discrepant views may lie in the time scale of hemodynamic variability; short time scale variability appears to be cerebroprotective, while mid to longer term fluctuations are associated with primary and secondary end-organ dysfunction.
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Affiliation(s)
- Caroline A Rickards
- Department of Integrative Physiology, Cardiovascular Research Institute, University of North Texas Health Science Center Fort Worth, TX, USA
| | - Yu-Chieh Tzeng
- Cardiovascular Systems Laboratory, Centre for Translational Physiology, University of Otago Wellington, New Zealand
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Pierro ML, Kainerstorfer JM, Civiletto A, Weiner DE, Sassaroli A, Hallacoglu B, Fantini S. Reduced speed of microvascular blood flow in hemodialysis patients versus healthy controls: a coherent hemodynamics spectroscopy study. J Biomed Opt 2014; 19:026005. [PMID: 24522805 PMCID: PMC3922146 DOI: 10.1117/1.jbo.19.2.026005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Revised: 01/08/2014] [Accepted: 01/10/2014] [Indexed: 05/19/2023]
Abstract
We present a pilot clinical application of coherent hemodynamics spectroscopy (CHS), a technique to investigate cerebral hemodynamics at the microcirculatory level. CHS relies on frequency-resolved measurements of induced cerebral hemodynamic oscillations that are measured with near-infrared spectroscopy (NIRS) and analyzed with a hemodynamic model. We have used cyclic inflation (200 mmHg) and deflation of a pneumatic cuff placed around the subject's thigh at seven frequencies in the range of 0.03 to 0.17 Hz to generate CHS spectra and to obtain a set of physiological parameters that include the blood transit times in the cerebral microcirculation, the cutoff frequency for cerebral autoregulation, and blood volume ratios across the three different compartments. We have investigated five hemodialysis patients, during the hemodialysis procedure, and six healthy subjects. We have found that the blood transit time in the cerebral microcirculation is significantly longer in hemodialysis patients with respect to healthy subjects. No significant differences were observed between the two groups in terms of autoregulation efficiency and blood volume ratios. The demonstration of the applicability of CHS in a clinical setting and its sensitivity to the highly important cerebral microcirculation may open up new opportunities for NIRS applications in research and in medical diagnostics and monitoring.
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Affiliation(s)
- Michele L. Pierro
- Tufts University, Department of Biomedical Engineering, 4 Colby Street, Medford, Massachusetts 02155
| | - Jana M. Kainerstorfer
- Tufts University, Department of Biomedical Engineering, 4 Colby Street, Medford, Massachusetts 02155
- Address all correspondence to: Jana M. Kainerstorfer, E-mail:
| | - Amanda Civiletto
- Tufts Medical Center, 800 Washington Street, Boston, Massachusetts 02111
| | - Daniel E. Weiner
- Tufts Medical Center, 800 Washington Street, Boston, Massachusetts 02111
| | - Angelo Sassaroli
- Tufts University, Department of Biomedical Engineering, 4 Colby Street, Medford, Massachusetts 02155
| | - Bertan Hallacoglu
- Tufts University, Department of Biomedical Engineering, 4 Colby Street, Medford, Massachusetts 02155
| | - Sergio Fantini
- Tufts University, Department of Biomedical Engineering, 4 Colby Street, Medford, Massachusetts 02155
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