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Langri DS, Sunar U. Non-Invasive Continuous Optical Monitoring of Cerebral Blood Flow after Traumatic Brain Injury in Mice Using Fiber Camera-Based Speckle Contrast Optical Spectroscopy. Brain Sci 2023; 13:1365. [PMID: 37891734 PMCID: PMC10605647 DOI: 10.3390/brainsci13101365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 09/05/2023] [Accepted: 09/15/2023] [Indexed: 10/29/2023] Open
Abstract
Neurocritical care focuses on monitoring cerebral blood flow (CBF) to prevent secondary brain injuries before damage becomes irreversible. Thus, there is a critical unmet need for continuous neuromonitoring methods to quantify CBF within the vulnerable cortex continuously and non-invasively. Animal models and imaging biomarkers can provide valuable insights into the mechanisms and kinetics of head injury, as well as insights for potential treatment strategies. For this purpose, we implemented an optical technique for continuous monitoring of blood flow changes after a closed head injury in a mouse model, which is based on laser speckle contrast imaging and a fiber camera-based approach. Our results indicate a significant decrease (~10%, p-value < 0.05) in blood flow within 30 min of a closed head injury. Furthermore, the low-frequency oscillation analysis also indicated much lower power in the trauma group compared to the control group. Overall, blood flow has the potential to be a biomarker for head injuries in the early phase of a trauma, and the system is useful for continuous monitoring with the potential for clinical translation.
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Affiliation(s)
- Dharminder S. Langri
- Department of Biomedical Engineering, Wright State University, Dayton, OH 45435, USA;
| | - Ulas Sunar
- Department of Biomedical Engineering, Stony Brook University, New York, NY 11794, USA
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Becker S, Klein F, König K, Mathys C, Liman T, Witt K. Assessment of dynamic cerebral autoregulation in near-infrared spectroscopy using short channels: A feasibility study in acute ischemic stroke patients. Front Neurol 2022; 13:1028864. [PMID: 36479048 PMCID: PMC9719939 DOI: 10.3389/fneur.2022.1028864] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Accepted: 11/04/2022] [Indexed: 10/07/2023] Open
Abstract
Introduction In acute ischemic stroke, progressive impairment of cerebral autoregulation (CA) is frequent and associated with unfavorable outcomes. Easy assessment of cerebral blood flow and CA in stroke units bedside tools like near-infrared spectroscopy (NIRS) might improve early detection of CA deterioration. This study aimed to assess dynamic CA with multichannel CW-NIRS in acute ischemic stroke (AIS) patients compared to agematched healthy controls. Methods CA reaction was amplified by changes in head of bed position. Long- and short channels were used to monitor systemic artery pressure- and intracranial oscillations simultaneously. Gain and phase shift in spontaneous low- and very low-frequency oscillations (LFO, VLFO) of blood pressure were assessed. Results A total of 54 participants, 27 with AIS and 27 age-matched controls were included. Gain was significantly lower in the AIS group in the LFO range (i) when the upper body was steadily elevated to 30. and (ii) after its abrupt elevation to 30°. No other differences were found between groups. Discussion This study demonstrates the feasibility of NIRS short channels to measure CA in AIS patients in one single instrument. A lower gain in AIS might indicate decreased CA activity in this pilot study, but further studies investigating the role of NIRS short channels in AIS are needed.
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Affiliation(s)
- Sabeth Becker
- Department of Neurology, School of Medicine and Health Sciences, Carl von Ossietzky University of Oldenburg, Oldenburg, Germany
| | - Franziska Klein
- Neurocognition and Functional Neurorehabilitation Group, Neuropsychology Lab, Department of Psychology, Faculty of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany
| | - Katja König
- Department of Neurology, School of Medicine and Health Sciences, Carl von Ossietzky University of Oldenburg, Oldenburg, Germany
- University Clinic for Neurology, Evangelical Hospital, Oldenburg, Germany
| | - Christian Mathys
- Institute of Radiology and Neuroradiology, Evangelical Hospital, Oldenburg, Germany
- Research Centre Neurosensory Science, Department of Human Medicine, Faculty of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany
| | - Thomas Liman
- Department of Neurology, School of Medicine and Health Sciences, Carl von Ossietzky University of Oldenburg, Oldenburg, Germany
- University Clinic for Neurology, Evangelical Hospital, Oldenburg, Germany
| | - Karsten Witt
- Department of Neurology, School of Medicine and Health Sciences, Carl von Ossietzky University of Oldenburg, Oldenburg, Germany
- University Clinic for Neurology, Evangelical Hospital, Oldenburg, Germany
- Institute of Radiology and Neuroradiology, Evangelical Hospital, Oldenburg, Germany
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Bahrani AA, Kong W, Shang Y, Huang C, Smith CD, Powell DK, Jiang Y, Rayapati AO, Jicha GA, Yu G. Diffuse optical assessment of cerebral-autoregulation in older adults stratified by cerebrovascular risk. JOURNAL OF BIOPHOTONICS 2020; 13:e202000073. [PMID: 32533642 PMCID: PMC8824485 DOI: 10.1002/jbio.202000073] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 05/06/2020] [Accepted: 06/09/2020] [Indexed: 05/04/2023]
Abstract
Diagnosis of cerebrovascular disease (CVD) at early stages is essential for preventing sequential complications. CVD is often associated with abnormal cerebral microvasculature, which may impact cerebral-autoregulation (CA). A novel hybrid near-infrared diffuse optical instrument and a finger plethysmograph were used to simultaneously detect low-frequency oscillations (LFOs) of cerebral blood flow (CBF), oxy-hemoglobin concentration ([HbO2 ]), deoxy-hemoglobin concentration ([Hb]) and mean arterial pressure (MAP) in older adults before, during and after 70° head-up-tilting (HUT). The participants with valid data were divided based on Framingham risk score (FRS, 1-30 points) into low-risk (FRS ≤15, n = 13) and high-risk (FRS >15, n = 11) groups for developing CVD. The LFO gains were determined by transfer function analyses with MAP as the input, and CBF, [HbO2 ] and [Hb] as the outputs (CA ∝ 1/Gain). At resting-baseline, LFO gains in the high-risk group were relatively lower compared to the low-risk group. The lower baseline gains in the high-risk group may attribute to compensatory mechanisms to maintain stronger steady-state CAs. However, HUT resulted in smaller gain reductions in the high-risk group compared to the low-risk group, suggesting weaker dynamic CAs. LFO gains are potentially valuable biomarkers for early detection of CVD based on associations with CAs.
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Affiliation(s)
- Ahmed A. Bahrani
- Department of Biomedical Engineering, University of Kentucky, Lexington, Kentucky
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, Kentucky
- Biomedical Engineering Department, Al-Khwarizmi College of Engineering, University of Baghdad, Baghdad, Iraq
| | - Weikai Kong
- Department of Biomedical Engineering, University of Kentucky, Lexington, Kentucky
| | - Yu Shang
- Shanxi Provincial Key Laboratory for Biomedical Imaging and Big Data, North University of China, Shanxi, China
| | - Chong Huang
- Department of Biomedical Engineering, University of Kentucky, Lexington, Kentucky
| | - Charles D. Smith
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, Kentucky
- Magnetic Resonance Imaging and Spectroscopy Center (MRISC), University of Kentucky, Lexington, Kentucky
- Department of Neurology, University of Kentucky, Lexington, Kentucky
| | - David K. Powell
- Magnetic Resonance Imaging and Spectroscopy Center (MRISC), University of Kentucky, Lexington, Kentucky
- Neuroscience Department, University of Kentucky, Lexington, Kentucky
| | - Yang Jiang
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, Kentucky
- Magnetic Resonance Imaging and Spectroscopy Center (MRISC), University of Kentucky, Lexington, Kentucky
- Department of Behavioral Science, University of Kentucky, Lexington, Kentucky
| | - Abner O. Rayapati
- Department of Psychiatry, University of Kentucky, Lexington, Kentucky
| | - Gregory A. Jicha
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, Kentucky
- Magnetic Resonance Imaging and Spectroscopy Center (MRISC), University of Kentucky, Lexington, Kentucky
- Department of Neurology, University of Kentucky, Lexington, Kentucky
| | - Guoqiang Yu
- Department of Biomedical Engineering, University of Kentucky, Lexington, Kentucky
- Correspondence: Guoqiang Yu, Department of Biomedical Engineering, University of Kentucky, Lexington, KY 40506,
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Elting JWJ, Tas J, Aries MJ, Czosnyka M, Maurits NM. Dynamic cerebral autoregulation estimates derived from near infrared spectroscopy and transcranial Doppler are similar after correction for transit time and blood flow and blood volume oscillations. J Cereb Blood Flow Metab 2020; 40:135-149. [PMID: 30353763 PMCID: PMC6927073 DOI: 10.1177/0271678x18806107] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
We analysed mean arterial blood pressure, cerebral blood flow velocity, oxygenated haemoglobin and deoxygenated haemoglobin signals to estimate dynamic cerebral autoregulation. We compared macrovascular (mean arterial blood pressure-cerebral blood flow velocity) and microvascular (oxygenated haemoglobin-deoxygenated haemoglobin) dynamic cerebral autoregulation estimates during three different conditions: rest, mild hypocapnia and hypercapnia. Microvascular dynamic cerebral autoregulation estimates were created by introducing the constant time lag plus constant phase shift model, which enables correction for transit time, blood flow and blood volume oscillations (TT-BF/BV correction). After TT-BF/BV correction, a significant agreement between mean arterial blood pressure-cerebral blood flow velocity and oxygenated haemoglobin-deoxygenated haemoglobin phase differences in the low frequency band was found during rest (left: intraclass correlation=0.6, median phase difference 29.5° vs. 30.7°, right: intraclass correlation=0.56, median phase difference 32.6° vs. 39.8°) and mild hypocapnia (left: intraclass correlation=0.73, median phase difference 48.6° vs. 43.3°, right: intraclass correlation=0.70, median phase difference 52.1° vs. 61.8°). During hypercapnia, the mean transit time decreased and blood volume oscillations became much more prominent, except for very low frequencies. The transit time related to blood flow oscillations was remarkably stable during all conditions. We conclude that non-invasive microvascular dynamic cerebral autoregulation estimates are similar to macrovascular dynamic cerebral autoregulation estimates, after TT-BF/BV correction is applied. These findings may increase the feasibility of non-invasive continuous autoregulation monitoring and guided therapy in clinical situations.
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Affiliation(s)
- Jan Willem J Elting
- Department of Neurology, University Medical Center Groningen, Groningen, The Netherlands
| | - Jeanette Tas
- Department of Neurology, University Medical Center Groningen, Groningen, The Netherlands
| | - Marcel Jh Aries
- Department of Intensive Care, Maastricht University Medical Center, Maastricht, The Netherlands.,Brain Physics Group, Department of Clinical Neurosciences, Addenbrooke's Hospital, University of Cambridge, Cambridge, UK
| | - Marek Czosnyka
- Brain Physics Group, Department of Clinical Neurosciences, Addenbrooke's Hospital, University of Cambridge, Cambridge, UK.,Institute of Electronic Systems, Warsaw University of Technology, Warsaw, Poland
| | - Natasha M Maurits
- Department of Neurology, University Medical Center Groningen, Groningen, The Netherlands
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Müller M, Österreich M. Cerebral Microcirculatory Blood Flow Dynamics During Rest and a Continuous Motor Task. Front Physiol 2019; 10:1355. [PMID: 31708802 PMCID: PMC6821676 DOI: 10.3389/fphys.2019.01355] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Accepted: 10/11/2019] [Indexed: 12/13/2022] Open
Abstract
Objectives: To examine the brain’s microcirculatory response over the course of a continuous 5-min elbow movement task in order to estimate its potential role in grading vaso-neural coupling compared to the macrocirculatory response. Methods: We simultaneously recorded cerebral blood flow velocity (CBFV), changes in oxygenated/deoxygenated hemoglobin concentrations ([oxHb], [deoxHb]), blood pressure (BP), and end-tidal CO2 over 5-min periods of rest and left elbow movements in 24 healthy persons (13 women and 11 men of mean age ± SD, 38 ± 11 years). A low frequency range (0.07–0.15 Hz) was used for analysis by transfer function estimates of phase and gain. Results: Elbow movement led to a small BP increase (mean BP at rest 83 mm Hg, at movement 87; p < 0.01) and a small ETCO2 decrease (at rest 44.6 mm Hg, at movement 41.7 mm Hg; p < 0.01). Further, it increased BP-[oxHb] phase from 55° (both sides) to 74° (right; p < 0.05)/69° (left; p < 0.05), and BP-[deoxHb] phase from 264° (right)/270° (left) to 288° (right; p < 0.05)/297° (left; p = 0.09). The cerebral mean transit time at 0.1 Hz of 5.6 s of rest remained unchanged by movement. Elbow movement significantly decreased BP-CBFV gain on both sides, and BP-CBFV phase only on the right side (p = 0.05). Conclusion: Elbow movement leads to an increased time delay between BP and [oxHb]/[deoxHb] while leaving the cerebral mean transit time unchanged. Phase shifting is usually the more robust parameter when using a transfer function to estimate dynamic cerebral autoregulation; phase shifting at the microcirculatory level seems to be a better marker of VNC-induced changes than phase shifting between BP and CBFV.
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Affiliation(s)
- Martin Müller
- Neurovascular Laboratory, Neurocenter, Lucerne Kantonsspital, Lucerne, Switzerland
| | - Mareike Österreich
- Neurovascular Laboratory, Neurocenter, Lucerne Kantonsspital, Lucerne, Switzerland
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Goltsov A, Anisimova AV, Zakharkina M, Krupatkin AI, Sidorov VV, Sokolovski SG, Rafailov E. Bifurcation in Blood Oscillatory Rhythms for Patients with Ischemic Stroke: A Small Scale Clinical Trial using Laser Doppler Flowmetry and Computational Modeling of Vasomotion. Front Physiol 2017; 8:160. [PMID: 28386231 PMCID: PMC5362641 DOI: 10.3389/fphys.2017.00160] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2016] [Accepted: 03/02/2017] [Indexed: 11/18/2022] Open
Abstract
We describe application of spectral analysis of laser Doppler flowmetry (LDF) signals to investigation of cerebrovascular haemodynamics in patients with post-acute ischemic stroke (AIS) and cerebrovascular insufficiency. LDF was performed from 3 to 7 days after the onset of AIS on forehead in the right and left supraorbital regions in patients. Analysis of LDF signals showed that perfusion in the microvasculature in AIS patients was lower than that in patients with cerebrovascular insufficiency. As a result of wavelet analysis of the LDF signals we obtained activation of the vasomotion in the frequency range of myogenic oscillation of 0.1 Hz and predominantly nutritive regime microcirculation after systemic thrombolytic therapy of the AIS patients. In case of significant stroke size, myogenic activity, and nutritive pattern microhaemodynamics were reduced, in some cases non-nutritive pattern and/or venular stasis was revealed. Wavelet analysis of the LDF signals also showed asymmetry in wavelet spectra of the LDF signals obtained in stroke-affected and unaffected hemispheres in the AIS patients. A mechanism underlying the observed asymmetry was analyzed by computational modeling of vasomotion developed in Arciero and Secomb (2012). We applied this model to describe relaxation oscillation of arteriole diameter which is forced by myogenic oscillation induced by synchronous calcium oscillation in vascular smooth muscle cells. Calculation showed that vasomotion frequency spectrum at the low-frequency range (0.01 Hz) is reciprocally modulated by myogenic oscillation (0.1 Hz) that correlates with experimental observation of inter-hemispheric variation in the LDF spectrum.
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Affiliation(s)
- Alexey Goltsov
- Division of Science, School of Science, Engineering and Technology, Abertay University Dundee, UK
| | - Anastasia V Anisimova
- Department of Neurology, Neurosurgery and Medical Genetics, Pirogov Russian National Research Medical University, First City Hospital Moscow, Russia
| | - Maria Zakharkina
- Department of Neurology, Neurosurgery and Medical Genetics, Pirogov Russian National Research Medical University, First City Hospital Moscow, Russia
| | - Alexander I Krupatkin
- Department of Functional Diagnostics, Priorov's Central Institute of Traumatology and Orthopedics Moscow, Russia
| | | | - Sergei G Sokolovski
- Optoelectronics and Biomedical Photonics Group, Photonics and Nanoscience Group, Aston Institute of Photonic Technologies, Aston University Birmingham, UK
| | - Edik Rafailov
- Optoelectronics and Biomedical Photonics Group, Photonics and Nanoscience Group, Aston Institute of Photonic Technologies, Aston University Birmingham, UK
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Müller MWD, Österreich M, Müller A, Lygeros J. Assessment of the Brain's Macro- and Micro-Circulatory Blood Flow Responses to CO2 via Transfer Function Analysis. Front Physiol 2016; 7:162. [PMID: 27242536 PMCID: PMC4860618 DOI: 10.3389/fphys.2016.00162] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Accepted: 04/15/2016] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES At present, there is no standard bedside method for assessing cerebral autoregulation (CA) with high temporal resolution. We combined the two methods most commonly used for this purpose, transcranial Doppler sonography (TCD, macro-circulation level), and near-infrared spectroscopy (NIRS, micro-circulation level), in an attempt to identify the most promising approach. METHODS In eight healthy subjects (5 women; mean age, 38 ± 10 years), CA disturbance was achieved by adding carbon dioxide (CO2) to the breathing air. We simultaneously recorded end-tidal CO2 (ETCO2), blood pressure (BP; non-invasively at the fingertip), and cerebral blood flow velocity (CBFV) in both middle cerebral arteries using TCD and determined oxygenated and deoxygenated hemoglobin levels using NIRS. For the analysis, we used transfer function calculations in the low-frequency band (0.07-0.15 Hz) to compare BP-CBFV, BP-oxygenated hemoglobin (OxHb), BP-tissue oxygenation index (TOI), CBFV-OxHb, and CBFV-TOI. RESULTS ETCO2 increased from 37 ± 2 to 44 ± 3 mmHg. The CO2-induced CBFV increase significantly correlated with the OxHb increase (R (2) = 0.526, p < 0.001). Compared with baseline, the mean CO2 administration phase shift (in radians) significantly increased (p < 0.005) from -0.67 ± 0.20 to -0.51 ± 0.25 in the BP-CBFV system, and decreased from 1.21 ± 0.81 to -0.05 ± 0.91 in the CBFV-OxHb system, and from 0.94 ± 1.22 to -0.24 ± 1.0 in the CBFV-TOI system; no change was observed for BP-OxHb (0.38 ± 1.17 to 0.41 ± 1.42). Gain changed significantly only in the BP-CBFV system. The correlation between the ETCO2 change and phase change was higher in the CBFV-OxHb system [r = -0.60; 95% confidence interval (CI): -0.16, -0.84; p < 0.01] than in the BP-CBFV system (r = 0.52; 95% CI: 0.03, 0.08; p < 0.05). CONCLUSION The transfer function characterizes the blood flow transition from macro- to micro-circulation by time delay only. The CBFV-OxHb system response with a broader phase shift distribution offers the prospect of a more detailed grading of CA responses. Whether this is of clinical relevance needs further studies in different patient populations.
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Affiliation(s)
- Martin W-D Müller
- Department of Neurology and Neurorehabilitation, Kantonsspital Lucerne Lucerne, Switzerland
| | - Mareike Österreich
- Department of Neurology and Neurorehabilitation, Kantonsspital Lucerne Lucerne, Switzerland
| | - Andreas Müller
- Department of Neurology and Neurorehabilitation, Kantonsspital Lucerne Lucerne, Switzerland
| | - John Lygeros
- Automatic Control Laboratory, ETH Zurich Zurich, Switzerland
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Dullaart RP, Al-Daghri NM, Ashina M, Bouzas-Mosquera A, Brunetti ND, Buechler C, Chen HS, Corrales JJ, D'Archivio M, Dei Cas A, Pino GG, Gómez-Abril SA, Győri D, Haslacher H, Herder C, Kerstens MN, Koutsilieris M, Lombardi C, Lupattelli G, Mócsai A, Msaouel P, Orfao A, Ormazabal P, Pacher R, Perkmann T, Peteiro J, Plischke M, Reynaert NL, Ricci MA, Robles NR, Rocha M, Rutten EP, Sabico S, Santamaria F, Santoro F, Schmid A, Schmidt M, Schytz HW, Shyu KG, Tada H, Thorand B, Valerio G, Vesely DL, Wu TE, Yamagishi M, Yeh YT. Research update for articles published in EJCI in 2012. Eur J Clin Invest 2014. [DOI: 10.1111/eci.12319] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Very-low-frequency oscillations of cerebral hemodynamics and blood pressure are affected by aging and cognitive load. Neuroimage 2014; 85 Pt 1:608-15. [DOI: 10.1016/j.neuroimage.2013.04.107] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Revised: 04/04/2013] [Accepted: 04/26/2013] [Indexed: 11/22/2022] Open
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Scholkmann F, Kleiser S, Metz AJ, Zimmermann R, Mata Pavia J, Wolf U, Wolf M. A review on continuous wave functional near-infrared spectroscopy and imaging instrumentation and methodology. Neuroimage 2014; 85 Pt 1:6-27. [PMID: 23684868 DOI: 10.1016/j.neuroimage.2013.05.004] [Citation(s) in RCA: 993] [Impact Index Per Article: 99.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 04/12/2013] [Accepted: 05/03/2013] [Indexed: 01/09/2023] Open
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Phillip D, Iversen HK, Schytz HW, Selb J, Boas DA, Ashina M. Altered Low Frequency Oscillations of Cortical Vessels in Patients with Cerebrovascular Occlusive Disease - A NIRS Study. Front Neurol 2013; 4:204. [PMID: 24379801 PMCID: PMC3864103 DOI: 10.3389/fneur.2013.00204] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Accepted: 12/03/2013] [Indexed: 11/30/2022] Open
Abstract
Analysis of cerebral autoregulation by measuring spontaneous oscillations in the low frequency spectrum of cerebral cortical vessels might be a useful tool for assessing risk and investigating different treatment strategies in carotid artery disease and stroke. Near infrared spectroscopy (NIRS) is a non-invasive optical method to investigate regional changes in oxygenated (oxyHb) and deoxygenated hemoglobin (deoxyHb) in the outermost layers of the cerebral cortex. In the present study we examined oxyHb low frequency oscillations, believed to reflect cortical cerebral autoregulation, in 16 patients with both symptomatic carotid occlusive disease and cerebral hypoperfusion in comparison to healthy controls. Each hemisphere was examined with two NIRS channels using a 3 cm source detector distance. Arterial blood pressure (ABP) was measured via a finger plethysmograph. Using transfer function analysis ABP-oxyHb phase shift and gain as well as inter-hemispheric phase shift and amplitude ratio were assessed. We found that inter-hemispheric amplitude ratio was significantly altered in hypoperfusion patients compared to healthy controls (P = 0.010), because of relatively lower amplitude on the hypoperfusion side. The inter-hemispheric phase shift showed a trend (P = 0.061) toward increased phase shift in hypoperfusion patients compared to controls. We found no statistical difference between hemispheres in hypoperfusion patients for phase shift or gain values. There were no differences between the hypoperfusion side and controls for phase shift or gain values. These preliminary results suggest an impairment of autoregulation in hypoperfusion patients at the cortical level detected by NIRS.
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Affiliation(s)
- Dorte Phillip
- Danish Headache Center, Glostrup Hospital, University of Copenhagen , Glostrup , Denmark
| | - Helle K Iversen
- Stroke Unit, Department of Neurology, Glostrup Hospital, University of Copenhagen , Glostrup , Denmark
| | - Henrik W Schytz
- Danish Headache Center, Glostrup Hospital, University of Copenhagen , Glostrup , Denmark
| | - Juliette Selb
- Photon Migration Imaging Laboratory, Athinoula A. Martinos Center for Biomedical Imaging, Harvard Medical School , Boston, MA , USA
| | - David A Boas
- Photon Migration Imaging Laboratory, Athinoula A. Martinos Center for Biomedical Imaging, Harvard Medical School , Boston, MA , USA
| | - Messoud Ashina
- Danish Headache Center, Glostrup Hospital, University of Copenhagen , Glostrup , Denmark
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Pierro ML, Hallacoglu B, Sassaroli A, Kainerstorfer JM, Fantini S. Validation of a novel hemodynamic model for coherent hemodynamics spectroscopy (CHS) and functional brain studies with fNIRS and fMRI. Neuroimage 2013; 85 Pt 1:222-33. [PMID: 23562703 DOI: 10.1016/j.neuroimage.2013.03.037] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2012] [Revised: 03/13/2013] [Accepted: 03/25/2013] [Indexed: 01/08/2023] Open
Abstract
We report an experimental validation and applications of the new hemodynamic model presented in the companion article (Fantini, 2014-this issue) both in the frequency domain and in the time domain. In the frequency domain, we have performed diffuse optical measurements for coherent hemodynamics spectroscopy (CHS) on the brain and calf muscle of human subjects, showing that the hemodynamic model predictions (both in terms of spectral shapes and absolute spectral values) are confirmed experimentally. We show how the quantitative analysis based on the new model allows for autoregulation measurements from brain data, and provides an analytical description of near-infrared spiroximetry from muscle data. In the time domain, we have used data from the literature to perform a comparison between brain activation signals measured with functional near-infrared spectroscopy (fNIRS) or with blood oxygenation level dependent (BOLD) fMRI, and the corresponding signals predicted by the new model. This comparison shows an excellent agreement between the model predictions and the reported fNIRS and BOLD fMRI signals. This new hemodynamic model provides a valuable tool for brain studies with hemodynamic-based techniques.
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Affiliation(s)
- Michele L Pierro
- Department of Biomedical Engineering, Tufts University, Medford, MA 02155, USA.
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Schytz HW, Jensen BE, Jennum P, Selb J, Boas DA, Ashina M. Low-frequency oscillations and vasoreactivity of cortical vessels in obstructive sleep apnea during wakefulness: a near infrared spectroscopy study. Sleep Med 2013; 14:416-21. [PMID: 23517585 DOI: 10.1016/j.sleep.2012.12.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2012] [Revised: 11/09/2012] [Accepted: 12/17/2012] [Indexed: 11/29/2022]
Abstract
OBJECTIVES Effective nasal continuous positive airway pressure (CPAP) therapy reduces the cardiovascular outcomes associated with obstructive sleep apnea (OSA), but the mechanism behind this effect is unclear. We investigated if OSA patients during wakefulness showed signs of increased sympathetic activity and decreased vasoreactivity in cerebral cortical vessels as measured with near-infrared spectroscopy (NIRS), and if this may be reversed by CPAP treatment. SUBJECTS AND METHODS 23 OSA patients (mean age, 55y) naive to CPAP were included in a prospective interventional study. The OSA patients received CPAP therapy for at least two months. Cortical low-frequency oscillation (LFO) amplitudes and vasoreactivity during a breath hold test were measured with NIRS and were compared between baseline and after CPAP treatment. Baseline values also were compared to 13 healthy controls (mean age, 52y). RESULTS We found a decrease in LFO amplitudes after CPAP therapy (P=0.022) in OSA patients. We found no differences in LFO amplitudes between OSA patients and healthy controls (P=0.934). There were no differences in peak vascular response following breath hold tests in OSA patients before and after CPAP therapy (P=0.158) or compared to healthy controls (P=0.740). CONCLUSION Our NIRS study revealed a decrease in LFO amplitude following two months of CPAP treatment in OSA patients, which may reflect a decrease in sympathetic activity affecting cortical vessels.
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Affiliation(s)
- Henrik Winther Schytz
- Danish Headache Center and Department of Neurology, Glostrup University Hospital, Glostrup, Denmark
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