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Wang Q, Pan M, Kreiss L, Samaei S, Carp SA, Johansson JD, Zhang Y, Wu M, Horstmeyer R, Diop M, Li DDU. A comprehensive overview of diffuse correlation spectroscopy: Theoretical framework, recent advances in hardware, analysis, and applications. Neuroimage 2024; 298:120793. [PMID: 39153520 DOI: 10.1016/j.neuroimage.2024.120793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2024] [Revised: 07/23/2024] [Accepted: 08/14/2024] [Indexed: 08/19/2024] Open
Abstract
Diffuse correlation spectroscopy (DCS) is a powerful tool for assessing microvascular hemodynamic in deep tissues. Recent advances in sensors, lasers, and deep learning have further boosted the development of new DCS methods. However, newcomers might feel overwhelmed, not only by the already-complex DCS theoretical framework but also by the broad range of component options and system architectures. To facilitate new entry to this exciting field, we present a comprehensive review of DCS hardware architectures (continuous-wave, frequency-domain, and time-domain) and summarize corresponding theoretical models. Further, we discuss new applications of highly integrated silicon single-photon avalanche diode (SPAD) sensors in DCS, compare SPADs with existing sensors, and review other components (lasers, sensors, and correlators), as well as data analysis tools, including deep learning. Potential applications in medical diagnosis are discussed and an outlook for the future directions is provided, to offer effective guidance to embark on DCS research.
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Affiliation(s)
- Quan Wang
- Department of Biomedical Engineering, Faculty of Engineering, University of Strathclyde, Glasgow, United Kingdom
| | - Mingliang Pan
- Department of Biomedical Engineering, Faculty of Engineering, University of Strathclyde, Glasgow, United Kingdom
| | - Lucas Kreiss
- Department of Biomedical Engineering, Duke University, Durham, NC, United States
| | - Saeed Samaei
- Department of Medical and Biophysics, Schulich School of Medical & Dentistry, Western University, London, Ontario, Canada; Lawson Health Research Institute, Imaging Program, London, Ontario, Canada
| | - Stefan A Carp
- Massachusetts General Hospital, Optics at Athinoula A. Martinos Center for Biomedical Imaging, Harvard Medical School, Charlestown, MA, United States
| | | | - Yuanzhe Zhang
- Department of Biomedical Engineering, Faculty of Engineering, University of Strathclyde, Glasgow, United Kingdom
| | - Melissa Wu
- Department of Biomedical Engineering, Duke University, Durham, NC, United States
| | - Roarke Horstmeyer
- Department of Biomedical Engineering, Duke University, Durham, NC, United States
| | - Mamadou Diop
- Department of Medical and Biophysics, Schulich School of Medical & Dentistry, Western University, London, Ontario, Canada; Lawson Health Research Institute, Imaging Program, London, Ontario, Canada
| | - David Day-Uei Li
- Department of Biomedical Engineering, Faculty of Engineering, University of Strathclyde, Glasgow, United Kingdom.
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Sarkar S, K M, Varma HM. Tunable dynamical tissue phantom for laser speckle imaging. BIOMEDICAL OPTICS EXPRESS 2024; 15:4737-4748. [PMID: 39347004 PMCID: PMC11427206 DOI: 10.1364/boe.528286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/24/2024] [Revised: 06/13/2024] [Accepted: 06/14/2024] [Indexed: 10/01/2024]
Abstract
We introduce a novel method to design and implement a tunable dynamical tissue phantom for laser speckle-based in-vivo blood flow imaging. This approach relies on stochastic differential equations (SDE) to control a piezoelectric actuator which, upon illuminated with a laser source, generates speckles of pre-defined probability density function and auto-correlation. The validation experiments show that the phantom can generate dynamic speckles that closely replicate both surfaces as well as deep tissue blood flow for a reasonably wide range and accuracy.
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Affiliation(s)
- Soumyajit Sarkar
- Department of Biosciences and Bioengineering, Indian Institute of Technology - Bombay, Mumbai 400076, India
| | - Murali K
- Department of Biosciences and Bioengineering, Indian Institute of Technology - Bombay, Mumbai 400076, India
| | - Hari M Varma
- Department of Biosciences and Bioengineering, Indian Institute of Technology - Bombay, Mumbai 400076, India
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3
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Huang YX, Mahler S, Dickson M, Abedi A, Tyszka JM, Lo YT, Russin J, Liu C, Yang C. Compact and cost-effective laser-powered speckle contrast optical spectroscopy fiber-free device for measuring cerebral blood flow. JOURNAL OF BIOMEDICAL OPTICS 2024; 29:067001. [PMID: 38826808 PMCID: PMC11140771 DOI: 10.1117/1.jbo.29.6.067001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Revised: 04/22/2024] [Accepted: 05/15/2024] [Indexed: 06/04/2024]
Abstract
Significance In the realm of cerebrovascular monitoring, primary metrics typically include blood pressure, which influences cerebral blood flow (CBF) and is contingent upon vessel radius. Measuring CBF noninvasively poses a persistent challenge, primarily attributed to the difficulty of accessing and obtaining signal from the brain. Aim Our study aims to introduce a compact speckle contrast optical spectroscopy device for noninvasive CBF measurements at long source-to-detector distances, offering cost-effectiveness, and scalability while tracking blood flow (BF) with remarkable sensitivity and temporal resolution. Approach The wearable sensor module consists solely of a laser diode and a board camera. It can be easily placed on a subject's head to measure BF at a sampling rate of 80 Hz. Results Compared to the single-fiber-based version, the proposed device achieved a signal gain of about 70 times, showed superior stability, reproducibility, and signal-to-noise ratio for measuring BF at long source-to-detector distances. The device can be distributed in multiple configurations around the head. Conclusions Given its cost-effectiveness, scalability, and simplicity, this laser-centric tool offers significant potential in advancing noninvasive cerebral monitoring technologies.
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Affiliation(s)
- Yu Xi Huang
- California Institute of Technology, Department of Electrical Engineering, Pasadena, California, United States
| | - Simon Mahler
- California Institute of Technology, Department of Electrical Engineering, Pasadena, California, United States
| | - Maya Dickson
- California Institute of Technology, Department of Electrical Engineering, Pasadena, California, United States
| | - Aidin Abedi
- University of Southern California, USC Neurorestoration Center, Department of Neurological Surgery, Los Angeles, California, United States
| | - Julian Michael Tyszka
- California Institute of Technology, Division of Humanities and Social Sciences, Pasadena, California, United States
| | - Yu Tung Lo
- University of Southern California, USC Neurorestoration Center, Department of Neurological Surgery, Los Angeles, California, United States
| | - Jonathan Russin
- University of Southern California, USC Neurorestoration Center, Department of Neurological Surgery, Los Angeles, California, United States
- Rancho Los Amigos National Rehabilitation Center, Downey, California, United States
| | - Charles Liu
- University of Southern California, USC Neurorestoration Center, Department of Neurological Surgery, Los Angeles, California, United States
- Rancho Los Amigos National Rehabilitation Center, Downey, California, United States
| | - Changhuei Yang
- California Institute of Technology, Department of Electrical Engineering, Pasadena, California, United States
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Cheng TY, Kim B, Zimmermann BB, Robinson MB, Renna M, Carp SA, Franceschini MA, Boas DA, Cheng X. Choosing a camera and optimizing system parameters for speckle contrast optical spectroscopy. Sci Rep 2024; 14:11915. [PMID: 38789499 PMCID: PMC11126420 DOI: 10.1038/s41598-024-62106-y] [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: 01/30/2024] [Accepted: 05/14/2024] [Indexed: 05/26/2024] Open
Abstract
Speckle contrast optical spectroscopy (SCOS) is an emerging camera-based technique that can measure human cerebral blood flow (CBF) with high signal-to-noise ratio (SNR). At low photon flux levels typically encountered in human CBF measurements, camera noise and nonidealities could significantly impact SCOS measurement SNR and accuracy. Thus, a guide for characterizing, selecting, and optimizing a camera for SCOS measurements is crucial for the development of next-generation optical devices for monitoring human CBF and brain function. Here, we provide such a guide and illustrate it by evaluating three commercially available complementary metal-oxide-semiconductor cameras, considering a variety of factors including linearity, read noise, and quantization distortion. We show that some cameras that are well-suited for general intensity imaging could be challenged in accurately quantifying spatial contrast for SCOS. We then determine the optimal operating parameters for the preferred camera among the three and demonstrate measurement of human CBF with this selected low-cost camera. This work establishes a guideline for characterizing and selecting cameras as well as for determining optimal parameters for SCOS systems.
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Affiliation(s)
- Tom Y Cheng
- Department of Biomedical Engineering, Neurophotonics Center, Boston University, Boston, MA, 02215, USA
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, 02129, USA
- Lincoln Laboratory, Massachusetts Institute of Technology, Lexington, MA, 02421, USA
| | - Byungchan Kim
- Department of Biomedical Engineering, Neurophotonics Center, Boston University, Boston, MA, 02215, USA
| | - Bernhard B Zimmermann
- Department of Biomedical Engineering, Neurophotonics Center, Boston University, Boston, MA, 02215, USA
| | - Mitchell B Robinson
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, 02129, USA
| | - Marco Renna
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, 02129, USA
| | - Stefan A Carp
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, 02129, USA
| | - Maria Angela Franceschini
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, 02129, USA
| | - David A Boas
- Department of Biomedical Engineering, Neurophotonics Center, Boston University, Boston, MA, 02215, USA
| | - Xiaojun Cheng
- Department of Biomedical Engineering, Neurophotonics Center, Boston University, Boston, MA, 02215, USA.
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Favilla CG, Baird GL, Grama K, Konecky S, Carter S, Smith W, Gitlevich R, Lebron-Cruz A, Yodh AG, McTaggart RA. Portable cerebral blood flow monitor to detect large vessel occlusion in patients with suspected stroke. J Neurointerv Surg 2024:jnis-2024-021536. [PMID: 38514189 DOI: 10.1136/jnis-2024-021536] [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: 01/25/2024] [Accepted: 03/10/2024] [Indexed: 03/23/2024]
Abstract
BACKGROUND Early detection of large vessel occlusion (LVO) facilitates triage to an appropriate stroke center to reduce treatment times and improve outcomes. Prehospital stroke scales are not sufficiently sensitive, so we investigated the ability of the portable Openwater optical blood flow monitor to detect LVO. METHODS Patients were prospectively enrolled at two comprehensive stroke centers during stroke alert evaluation within 24 hours of onset with National Institutes of Health Stroke Scale (NIHSS) score ≥2. A 70 s bedside optical blood flow scan generated cerebral blood flow waveforms based on relative changes in speckle contrast. Anterior circulation LVO was determined by CT angiography. A deep learning model trained on all patient data using fivefold cross-validation and learned discriminative representations from the raw speckle contrast waveform data. Receiver operating characteristic (ROC) analysis compared the Openwater diagnostic performance (ie, LVO detection) with prehospital stroke scales. RESULTS Among 135 patients, 52 (39%) had an anterior circulation LVO. The median NIHSS score was 8 (IQR 4-14). The Openwater instrument had 79% sensitivity and 84% specificity for the detection of LVO. The rapid arterial occlusion evaluation (RACE) scale had 60% sensitivity and 81% specificity and the Los Angeles motor scale (LAMS) had 50% sensitivity and 81% specificity. The binary Openwater classification (high-likelihood vs low-likelihood) had an area under the ROC (AUROC) of 0.82 (95% CI 0.75 to 0.88), which outperformed RACE (AUC 0.70; 95% CI 0.62 to 0.78; P=0.04) and LAMS (AUC 0.65; 95% CI 0.57 to 0.73; P=0.002). CONCLUSIONS The Openwater optical blood flow monitor outperformed prehospital stroke scales for the detection of LVO in patients undergoing acute stroke evaluation in the emergency department. These encouraging findings need to be validated in an independent test set and the prehospital environment.
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Affiliation(s)
- Christopher G Favilla
- Department of Neurology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Grayson L Baird
- Department of Interventional Radiology, Brown University, Providence, Rhode Island, USA
| | | | | | - Sarah Carter
- Department of Neurology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Wendy Smith
- Department of Diagnostic Imaging, Lifespan Health System, Providence, Rhode Island, USA
| | - Rebecca Gitlevich
- Department of Neurology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Alexa Lebron-Cruz
- Department of Neurology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Arjun G Yodh
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Ryan A McTaggart
- Department of Interventional Radiology, Brown University, Providence, Rhode Island, USA
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Huang YX, Mahler S, Dickson M, Abedi A, Tyszka JM, Lo YT, Russin J, Liu C, Yang C. A compact and cost-effective laser-powered speckle visibility spectroscopy (SVS) device for measuring cerebral blood flow. ARXIV 2024:arXiv:2401.16592v2. [PMID: 38351942 PMCID: PMC10862935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/19/2024]
Abstract
In the realm of cerebrovascular monitoring, primary metrics typically include blood pressure, which influences cerebral blood flow (CBF) and is contingent upon vessel radius. Measuring CBF non-invasively poses a persistent challenge, primarily attributed to the difficulty of accessing and obtaining signal from the brain. This study aims to introduce a compact speckle visibility spectroscopy (SVS) device designed for non-invasive CBF measurements, offering cost-effectiveness and scalability while tracking CBF with remarkable sensitivity and temporal resolution. The wearable hardware has a modular design approach consisting solely of a laser diode as the source and a meticulously selected board camera as the detector. They both can be easily placed on a subject's head to measure CBF with no additional optical elements. The SVS device can achieve a sampling rate of 80 Hz with minimal susceptibility to external disturbances. The device also achieves better SNR compared with traditional fiber-based SVS devices, capturing about 70 times more signal and showing superior stability and reproducibility. It is designed to be paired and distributed in multiple configurations around the head, and measure signals that exceed the quality of prior optical CBF measurement techniques. Given its cost-effectiveness, scalability, and simplicity, this laser-centric tool offers significant potential in advancing non-invasive cerebral monitoring technologies.
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Affiliation(s)
- Yu Xi Huang
- Department of Electrical Engineering, California Institute of Technology, Pasadena, California 91125, USA
| | - Simon Mahler
- Department of Electrical Engineering, California Institute of Technology, Pasadena, California 91125, USA
| | - Maya Dickson
- Department of Electrical Engineering, California Institute of Technology, Pasadena, California 91125, USA
| | - Aidin Abedi
- USC Neurorestoration Center and the Departments of Neurosurgery and Neurology, University of Southern California; Los Angeles, CA 90033, USA
| | - Julian M. Tyszka
- Division of Humanities and Social Sciences, California Institute of Technology, Pasadena, California 91125, USA
| | - Yu Tung Lo
- USC Neurorestoration Center and the Departments of Neurosurgery and Neurology, University of Southern California; Los Angeles, CA 90033, USA
| | - Jonathan Russin
- USC Neurorestoration Center and the Departments of Neurosurgery and Neurology, University of Southern California; Los Angeles, CA 90033, USA
| | - Charles Liu
- USC Neurorestoration Center and the Departments of Neurosurgery and Neurology, University of Southern California; Los Angeles, CA 90033, USA
| | - Changhuei Yang
- Department of Electrical Engineering, California Institute of Technology, Pasadena, California 91125, USA
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Favilla CG, Carter S, Hartl B, Gitlevich R, Mullen MT, Yodh AG, Baker WB, Konecky S. Validation of the Openwater wearable optical system: cerebral hemodynamic monitoring during a breath-hold maneuver. NEUROPHOTONICS 2024; 11:015008. [PMID: 38464864 PMCID: PMC10923543 DOI: 10.1117/1.nph.11.1.015008] [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: 10/18/2023] [Revised: 02/10/2024] [Accepted: 02/13/2024] [Indexed: 03/12/2024]
Abstract
Significance Bedside cerebral blood flow (CBF) monitoring has the potential to inform and improve care for acute neurologic diseases, but technical challenges limit the use of existing techniques in clinical practice. Aim Here, we validate the Openwater optical system, a novel wearable headset that uses laser speckle contrast to monitor microvascular hemodynamics. Approach We monitored 25 healthy adults with the Openwater system and concurrent transcranial Doppler (TCD) while performing a breath-hold maneuver to increase CBF. Relative blood flow (rBF) was derived from changes in speckle contrast, and relative blood volume (rBV) was derived from changes in speckle average intensity. Results A strong correlation was observed between beat-to-beat optical rBF and TCD-measured cerebral blood flow velocity (CBFv), R = 0.79 ; the slope of the linear fit indicates good agreement, 0.87 (95% CI: 0.83 - 0.92 ). Beat-to-beat rBV and CBFv were also strongly correlated, R = 0.72 , but as expected the two variables were not proportional; changes in rBV were smaller than CBFv changes, with linear fit slope of 0.18 (95% CI: 0.17 to 0.19). Further, strong agreement was found between rBF and CBFv waveform morphology and related metrics. Conclusions This first in vivo validation of the Openwater optical system highlights its potential as a cerebral hemodynamic monitor, but additional validation is needed in disease states.
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Affiliation(s)
- Christopher G. Favilla
- University of Pennsylvania, Department of Neurology, Philadelphia, Pennsylvania, United States
| | - Sarah Carter
- University of Pennsylvania, Department of Neurology, Philadelphia, Pennsylvania, United States
| | - Brad Hartl
- Openwater, San Francisco, California, United States
| | - Rebecca Gitlevich
- University of Pennsylvania, Department of Neurology, Philadelphia, Pennsylvania, United States
| | - Michael T. Mullen
- Temple University, Department of Neurology, Philadelphia, Pennsylvania, United States
| | - Arjun G. Yodh
- University of Pennsylvania, Department of Physics and Astronomy, Philadelphia, Pennsylvania, United States
| | - Wesley B. Baker
- Children’s Hospital of Philadelphia, Department of Neurology, Philadelphia, Pennsylvania, United States
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Robinson MB, Cheng TY, Renna M, Wu MM, Kim B, Cheng X, Boas DA, Franceschini MA, Carp SA. Comparing the performance potential of speckle contrast optical spectroscopy and diffuse correlation spectroscopy for cerebral blood flow monitoring using Monte Carlo simulations in realistic head geometries. NEUROPHOTONICS 2024; 11:015004. [PMID: 38282721 PMCID: PMC10821780 DOI: 10.1117/1.nph.11.1.015004] [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: 10/25/2023] [Revised: 12/13/2023] [Accepted: 01/08/2024] [Indexed: 01/30/2024]
Abstract
Significance The non-invasive measurement of cerebral blood flow based on diffuse optical techniques has seen increased interest as a research tool for cerebral perfusion monitoring in critical care and functional brain imaging. Diffuse correlation spectroscopy (DCS) and speckle contrast optical spectroscopy (SCOS) are two such techniques that measure complementary aspects of the fluctuating intensity signal, with DCS quantifying the temporal fluctuations of the signal and SCOS quantifying the spatial blurring of a speckle pattern. With the increasing interest in the use of these techniques, a thorough comparison would inform new adopters of the benefits of each technique. Aim We systematically evaluate the performance of DCS and SCOS for the measurement of cerebral blood flow. Approach Monte Carlo simulations of dynamic light scattering in an MRI-derived head model were performed. For both DCS and SCOS, estimates of sensitivity to cerebral blood flow changes, coefficient of variation of the measured blood flow, and the contrast-to-noise ratio of the measurement to the cerebral perfusion signal were calculated. By varying complementary aspects of data collection between the two methods, we investigated the performance benefits of different measurement strategies, including altering the number of modes per optical detector, the integration time/fitting time of the speckle measurement, and the laser source delivery strategy. Results Through comparison across these metrics with simulated detectors having realistic noise properties, we determine several guiding principles for the optimization of these techniques and report the performance comparison between the two over a range of measurement properties and tissue geometries. We find that SCOS outperforms DCS in terms of contrast-to-noise ratio for the cerebral blood flow signal in the ideal case simulated here but note that SCOS requires careful experimental calibrations to ensure accurate measurements of cerebral blood flow. Conclusion We provide design principles by which to evaluate the development of DCS and SCOS systems for their use in the measurement of cerebral blood flow.
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Affiliation(s)
- Mitchell B. Robinson
- Massachusetts General Hospital, Harvard Medical School, Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Boston, Massachusetts, United States
| | - Tom Y. Cheng
- Massachusetts General Hospital, Harvard Medical School, Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Boston, Massachusetts, United States
- Boston University, Neurophotonics Center, Department of Biomedical Engineering, Boston, Massachusetts, United States
| | - Marco Renna
- Massachusetts General Hospital, Harvard Medical School, Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Boston, Massachusetts, United States
| | - Melissa M. Wu
- Duke University, Department of Biomedical Engineering, Durham, North Carolina, United States
| | - Byungchan Kim
- Boston University, Neurophotonics Center, Department of Biomedical Engineering, Boston, Massachusetts, United States
| | - Xiaojun Cheng
- Boston University, Neurophotonics Center, Department of Biomedical Engineering, Boston, Massachusetts, United States
| | - David A. Boas
- Boston University, Neurophotonics Center, Department of Biomedical Engineering, Boston, Massachusetts, United States
| | - Maria Angela Franceschini
- Massachusetts General Hospital, Harvard Medical School, Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Boston, Massachusetts, United States
| | - Stefan A. Carp
- Massachusetts General Hospital, Harvard Medical School, Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Boston, Massachusetts, United States
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Favilla CG, Carter S, Hartl B, Gitlevich R, Mullen MT, Yodh AG, Baker WB, Konecky S. Validation of the Openwater wearable optical system: cerebral hemodynamic monitoring during a breath hold maneuver. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2023:2023.10.11.23296612. [PMID: 37873126 PMCID: PMC10592983 DOI: 10.1101/2023.10.11.23296612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Bedside cerebral blood flow (CBF) monitoring has the potential to inform and improve care for acute neurologic diseases, but technical challenges limit the use of existing techniques in clinical practice. Here we validate the Openwater optical system, a novel wearable headset that uses laser speckle contrast to monitor microvascular hemodynamics. We monitored 25 healthy adults with the Openwater system and concurrent transcranial Doppler (TCD) while performing a breath-hold maneuver to increase CBF. Relative blood flow (rBF) was derived from the changes in speckle contrast, and relative blood volume (rBV) was derived from the changes in speckle average intensity. A strong correlation was observed between beat-to-beat optical rBF and TCD-measured cerebral blood flow velocity (CBFv), R=0.79; the slope of the linear fit indicates good agreement, 0.87 (95% CI:0.83-0.92). Beat-to-beat rBV and CBFv were strongly correlated, R=0.72, but as expected the two variables were not proportional; changes in rBV were smaller than CBFv changes, with linear fit slope of 0.18 (95% CI:0.17-0.19). Further, strong agreement was found between rBF and CBFv waveform morphology and related metrics. This first in vivo validation of the Openwater optical system highlights its potential as a cerebral hemodynamic monitor, but additional validation is needed in disease states.
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