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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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2
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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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Huang YX, Mahler S, Mertz J, Yang C. Interferometric speckle visibility spectroscopy (iSVS) for measuring decorrelation time and dynamics of moving samples with enhanced signal-to-noise ratio and relaxed reference requirements. OPTICS EXPRESS 2023; 31:31253-31266. [PMID: 37710649 PMCID: PMC10544958 DOI: 10.1364/oe.499473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 08/15/2023] [Accepted: 08/25/2023] [Indexed: 09/16/2023]
Abstract
Diffusing wave spectroscopy (DWS) is a group of techniques used to measure the dynamics of a scattering medium in a non-invasive manner. DWS methods rely on detecting the speckle light field from the moving scattering medium and measuring the speckle decorrelation time to quantify the scattering medium's dynamics. For DWS, the signal-to-noise (SNR) is determined by the ratio between measured decorrelation time to the standard error of the measurement. This SNR is often low in certain applications because of high noise variances and low signal intensity, especially in biological applications with restricted exposure and emission levels. To address this photon-limited signal-to-noise ratio problem, we investigated, theoretically and experimentally, the SNR of an interferometric speckle visibility spectroscopy (iSVS) compared to more traditional DWS methods. We found that iSVS can provide excellent SNR performance through its ability to overcome camera noise. We also proved an iSVS system has more relaxed constraints on the reference beam properties. For an iSVS system to function properly, we only require the reference beam to exhibit local temporal stability, while incident angle, reference phase and intensity uniformity do not need to be constrained. This flexibility can potentially enable more unconventional iSVS implementation schemes.
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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
| | - Jerome Mertz
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts 02215, USA
- Neurophotonics Center, Boston University, Boston, Massachusetts 02215, USA
| | - Changhuei Yang
- Department of Electrical Engineering, California Institute of Technology, Pasadena, California 91125, USA
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Robinson MB, Renna M, Ozana N, Martin AN, Otic N, Carp SA, Franceschini MA. Portable, high speed blood flow measurements enabled by long wavelength, interferometric diffuse correlation spectroscopy (LW-iDCS). Sci Rep 2023; 13:8803. [PMID: 37258644 PMCID: PMC10232495 DOI: 10.1038/s41598-023-36074-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2023] [Accepted: 05/29/2023] [Indexed: 06/02/2023] Open
Abstract
Diffuse correlation spectroscopy (DCS) is an optical technique that can be used to characterize blood flow in tissue. The measurement of cerebral hemodynamics has arisen as a promising use case for DCS, though traditional implementations of DCS exhibit suboptimal signal-to-noise ratio (SNR) and cerebral sensitivity to make robust measurements of cerebral blood flow in adults. In this work, we present long wavelength, interferometric DCS (LW-iDCS), which combines the use of a longer illumination wavelength (1064 nm), multi-speckle, and interferometric detection, to improve both cerebral sensitivity and SNR. Through direct comparison with long wavelength DCS based on superconducting nanowire single photon detectors, we demonstrate an approximate 5× improvement in SNR over a single channel of LW-DCS in the measured blood flow signals in human subjects. We show equivalence of extracted blood flow between LW-DCS and LW-iDCS, and demonstrate the feasibility of LW-iDCS measured at 100 Hz at a source-detector separation of 3.5 cm. This improvement in performance has the potential to enable robust measurement of cerebral hemodynamics and unlock novel use cases for diffuse correlation spectroscopy.
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Affiliation(s)
- Mitchell B Robinson
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA.
| | - Marco Renna
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Nisan Ozana
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
- Bar-Ilan University, Tel Aviv District, Ramat Gan, Israel
| | - Alyssa N Martin
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Nikola Otic
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
- Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Stefan A Carp
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Maria Angela Franceschini
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
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Wayne MA, Sie EJ, Ulku AC, Mos P, Ardelean A, Marsili F, Bruschini C, Charbon E. Massively parallel, real-time multispeckle diffuse correlation spectroscopy using a 500 × 500 SPAD camera. BIOMEDICAL OPTICS EXPRESS 2023; 14:703-713. [PMID: 36874503 PMCID: PMC9979680 DOI: 10.1364/boe.473992] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 12/01/2022] [Accepted: 12/24/2022] [Indexed: 06/02/2023]
Abstract
Diffuse correlation spectroscopy (DCS) is a promising noninvasive technique for monitoring cerebral blood flow and measuring cortex functional activation tasks. Taking multiple parallel measurements has been shown to increase sensitivity, but is not easily scalable with discrete optical detectors. Here we show that with a large 500 × 500 SPAD array and an advanced FPGA design, we achieve an SNR gain of almost 500 over single-pixel mDCS performance. The system can also be reconfigured to sacrifice SNR to decrease correlation bin width, with 400 ns resolution being demonstrated over 8000 pixels.
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Affiliation(s)
- Michael A. Wayne
- Advanced Quantum Architecture Laboratory, École polytechnique fédérale de Lausanne, Rue de la Maladière 71B, Neuchatel, NE 2000, Switzerland
| | - Edbert J. Sie
- Reality Labs Research, Meta Platforms Inc., Menlo Park, CA 94025, USA
| | - Arin C. Ulku
- Advanced Quantum Architecture Laboratory, École polytechnique fédérale de Lausanne, Rue de la Maladière 71B, Neuchatel, NE 2000, Switzerland
| | - Paul Mos
- Advanced Quantum Architecture Laboratory, École polytechnique fédérale de Lausanne, Rue de la Maladière 71B, Neuchatel, NE 2000, Switzerland
| | - Andrei Ardelean
- Advanced Quantum Architecture Laboratory, École polytechnique fédérale de Lausanne, Rue de la Maladière 71B, Neuchatel, NE 2000, Switzerland
| | - Francesco Marsili
- Reality Labs Research, Meta Platforms Inc., Menlo Park, CA 94025, USA
| | - Claudio Bruschini
- Advanced Quantum Architecture Laboratory, École polytechnique fédérale de Lausanne, Rue de la Maladière 71B, Neuchatel, NE 2000, Switzerland
| | - Edoardo Charbon
- Advanced Quantum Architecture Laboratory, École polytechnique fédérale de Lausanne, Rue de la Maladière 71B, Neuchatel, NE 2000, Switzerland
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6
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Zhao M, Zhou W, Aparanji S, Mazumder D, Srinivasan VJ. Interferometric diffusing wave spectroscopy imaging with an electronically variable time-of-flight filter. OPTICA 2023; 10:42-52. [PMID: 37275218 PMCID: PMC10238083 DOI: 10.1364/optica.472471] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 11/09/2022] [Indexed: 06/07/2023]
Abstract
Diffuse optics (DO) is a light-based technique used to study the human brain, but it suffers from low brain specificity. Interferometric diffuse optics (iDO) promises to improve the quantitative accuracy and depth specificity of DO, and particularly, coherent light fluctuations (CLFs) arising from blood flow. iDO techniques have alternatively achieved either time-of-flight (TOF) discrimination or highly parallel detection, but not both at once. Here, we break this barrier with a single iDO instrument. Specifically, we show that rapid tuning of a temporally coherent laser during the sensor integration time increases the effective linewidth seen by a highly parallel interferometer. Using this concept to create a continuously variable and user-specified TOF filter, we demonstrate a solution to the canonical problem of DO, measuring optical properties. Then, with a deep TOF filter, we reduce scalp sensitivity of CLFs by 2.7 times at 1 cm source-collector separation. With this unique combination of desirable features, i.e., TOF-discrimination, spatial localization, and highly parallel CLF detection, we perform multiparametric imaging of light intensities and CLFs via the human forehead.
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Affiliation(s)
- Mingjun Zhao
- Department of Radiology, New York University Langone Health, 660 First Avenue, New York, New York 10016, USA
- Department of Biomedical Engineering, University of California Davis, 1 Shields Ave, Davis, California 95616, USA
| | - Wenjun Zhou
- Department of Biomedical Engineering, University of California Davis, 1 Shields Ave, Davis, California 95616, USA
- College of Optical and Electronic Technology, China Jiliang University, Hangzhou, Zhejiang 310018, China
| | - Santosh Aparanji
- Department of Radiology, New York University Langone Health, 660 First Avenue, New York, New York 10016, USA
| | - Dibbyan Mazumder
- Department of Radiology, New York University Langone Health, 660 First Avenue, New York, New York 10016, USA
| | - Vivek J. Srinivasan
- Department of Radiology, New York University Langone Health, 660 First Avenue, New York, New York 10016, USA
- Department of Biomedical Engineering, University of California Davis, 1 Shields Ave, Davis, California 95616, USA
- Department of Ophthalmology, New York University Langone Health, 550 First Avenue, New York, New York 10016, USA
- Tech4Health Institute, New York University Langone Health, 433 1st Avenue, New York, New York 10010, USA
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7
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Zhou W, Zhao M, Srinivasan VJ. Interferometric diffuse optics: recent advances and future outlook. NEUROPHOTONICS 2023; 10:013502. [PMID: 36284601 PMCID: PMC9587754 DOI: 10.1117/1.nph.10.1.013502] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 09/26/2022] [Indexed: 06/16/2023]
Abstract
The field of diffuse optics has provided a rich set of neurophotonic tools to measure the human brain noninvasively. Interferometric detection is a recent, exciting methodological development in this field. The approach is especially promising for the measurement of diffuse fluctuation signals related to blood flow. Benefitting from inexpensive sensor arrays, the interferometric approach has already dramatically improved throughput, enabling the measurement of brain blood flow faster and deeper. The interferometric approach can also achieve time-of-flight resolution, improving the accuracy of acquired signals. We provide a historical perspective and summary of recent work in the nascent area of interferometric diffuse optics. We predict that the convergence of interferometric technology with existing economies of scale will propel many advances in the years to come.
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Affiliation(s)
- Wenjun Zhou
- China Jiliang University, College of Optical and Electronic Technology, Hangzhou, China
- University of California Davis, Department of Biomedical Engineering, Davis, California, United States
| | - Mingjun Zhao
- University of California Davis, Department of Biomedical Engineering, Davis, California, United States
- New York University Langone Health, Department of Radiology, New York, New York, United States
| | - Vivek J. Srinivasan
- University of California Davis, Department of Biomedical Engineering, Davis, California, United States
- New York University Langone Health, Department of Radiology, New York, New York, United States
- New York University Langone Health, Department of Ophthalmology, New York, New York, United States
- New York University Langone Health, Tech4Health Institute, New York, New York, United States
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