1
|
Suwalski M, Shoemaker LN, Shoemaker JK, Diop M, Murkin JM, Chui J, St. Lawrence K, Milej D. Assessing the Sensitivity of Multi-Distance Hyperspectral NIRS to Changes in the Oxidation State of Cytochrome C Oxidase in the Brain. Metabolites 2022; 12:metabo12090817. [PMID: 36144221 PMCID: PMC9502461 DOI: 10.3390/metabo12090817] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 08/25/2022] [Accepted: 08/29/2022] [Indexed: 11/16/2022] Open
Abstract
Near-infrared spectroscopy (NIRS) measurements of tissue oxygen saturation (StO2) are frequently used during vascular and cardiac surgeries as a non-invasive means of assessing brain health; however, signal contamination from extracerebral tissues remains a concern. As an alternative, hyperspectral (hs)NIRS can be used to measure changes in the oxidation state of cytochrome c oxidase (ΔoxCCO), which provides greater sensitivity to the brain given its higher mitochondrial concentration versus the scalp. The purpose of this study was to evaluate the depth sensitivity of the oxCCO signal to changes occurring in the brain and extracerebral tissue components. The oxCCO assessment was conducted using multi-distance hsNIRS (source-detector separations = 1 and 3 cm), and metabolic changes were compared to changes in StO2. Ten participants were monitored using an in-house system combining hsNIRS and diffuse correlation spectroscopy (DCS). Data were acquired during carotid compression (CC) to reduce blood flow and hypercapnia to increase flow. Reducing blood flow by CC resulted in a significant decrease in oxCCO measured at rSD = 3 cm but not at 1 cm. In contrast, significant changes in StO2 were found at both distances. Hypercapnia caused significant increases in StO2 and oxCCO at rSD = 3 cm, but not at 1 cm. Extracerebral contamination resulted in elevated StO2 but not oxCCO after hypercapnia, which was significantly reduced by applying regression analysis. This study demonstrated that oxCCO was less sensitive to extracerebral signals than StO2.
Collapse
Affiliation(s)
- Marianne Suwalski
- Department of Medical Biophysics, Western University, 1151 Richmond St, London, ON N6A 3K7, Canada
- Imaging Division, Lawson Health Research Institute, Imaging Program, 268 Grosvenor St, London, ON N6A 4V2, Canada
- Correspondence: (M.S.); (D.M.)
| | - Leena N. Shoemaker
- Imaging Division, Lawson Health Research Institute, Imaging Program, 268 Grosvenor St, London, ON N6A 4V2, Canada
- Department of Kinesiology, Western University, 1151 Richmond St, London, ON N6A 3K7, Canada
| | - J. Kevin Shoemaker
- Department of Kinesiology, Western University, 1151 Richmond St, London, ON N6A 3K7, Canada
| | - Mamadou Diop
- Department of Medical Biophysics, Western University, 1151 Richmond St, London, ON N6A 3K7, Canada
- Imaging Division, Lawson Health Research Institute, Imaging Program, 268 Grosvenor St, London, ON N6A 4V2, Canada
| | - John M. Murkin
- Department of Anesthesiology and Perioperative Medicine, London Health Science Centre, 339 Windermere Rd, London, ON N6A 5A5, Canada
| | - Jason Chui
- Department of Anesthesiology and Perioperative Medicine, London Health Science Centre, 339 Windermere Rd, London, ON N6A 5A5, Canada
| | - Keith St. Lawrence
- Department of Medical Biophysics, Western University, 1151 Richmond St, London, ON N6A 3K7, Canada
- Imaging Division, Lawson Health Research Institute, Imaging Program, 268 Grosvenor St, London, ON N6A 4V2, Canada
| | - Daniel Milej
- Department of Medical Biophysics, Western University, 1151 Richmond St, London, ON N6A 3K7, Canada
- Imaging Division, Lawson Health Research Institute, Imaging Program, 268 Grosvenor St, London, ON N6A 4V2, Canada
- Correspondence: (M.S.); (D.M.)
| |
Collapse
|
2
|
Milej D, Rajaram A, Suwalski M, Morrison LB, Shoemaker LN, St. Lawrence K. Assessing the relationship between the cerebral metabolic rate of oxygen and the oxidation state of cytochrome-c-oxidase. NEUROPHOTONICS 2022; 9:035001. [PMID: 35874144 PMCID: PMC9298853 DOI: 10.1117/1.nph.9.3.035001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 06/22/2022] [Indexed: 05/07/2023]
Abstract
Significance: Hyperspectral near-infrared spectroscopy (hsNIRS) combined with diffuse correlation spectroscopy (DCS) provides a noninvasive approach for monitoring cerebral blood flow (CBF), the cerebral metabolic rate of oxygen ( CMRO 2 ) and the oxidation state of cytochrome-c-oxidase (oxCCO). CMRO 2 is calculated by combining tissue oxygen saturation ( S t O 2 ) with CBF, whereas oxCCO can be measured directly by hsNIRS. Although both reflect oxygen metabolism, a direct comparison has yet to be studied. Aim: We aim to investigate the relationship between CMRO 2 and oxCCO during periods of restricted oxygen delivery and lower metabolic demand. Approach: A hybrid hsNIRS/DCS system was used to measure hemodynamic and metabolic responses in piglets exposed to cerebral ischemia and anesthetic-induced reductions in brain activity. Results: Although a linear relationship was observed between CMRO 2 and oxCCO during ischemia, both exhibited a nonlinear relationship with respect to CBF. In contrast, linear correlation was sufficient to characterize the relationships between CMRO 2 and CBF and between the two metabolic markers during reduced metabolic demand. Conclusions: The observed relationship between CMRO 2 and oxCCO during periods of restricted oxygen delivery and lower metabolic demand indicates that the two metabolic markers are strongly correlated.
Collapse
Affiliation(s)
- Daniel Milej
- Lawson Health Research Institute, Imaging Program, London, Ontario, Canada
- Western University, Department of Medical Biophysics, London, Ontario, Canada
- Address all correspondence to Daniel Milej,
| | - Ajay Rajaram
- Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts, United States
| | - Marianne Suwalski
- Lawson Health Research Institute, Imaging Program, London, Ontario, Canada
- Western University, Department of Medical Biophysics, London, Ontario, Canada
| | - Laura B. Morrison
- Lawson Health Research Institute, Imaging Program, London, Ontario, Canada
| | - Leena N. Shoemaker
- Lawson Health Research Institute, Imaging Program, London, Ontario, Canada
- Western University, Department of Medical Biophysics, London, Ontario, Canada
- Western University, Department of Kinesiology, London, Ontario, Canada
| | - Keith St. Lawrence
- Lawson Health Research Institute, Imaging Program, London, Ontario, Canada
- Western University, Department of Medical Biophysics, London, Ontario, Canada
| |
Collapse
|
3
|
Mainard N, Tsiakaka O, Li S, Denoulet J, Messaoudene K, Vialle R, Feruglio S. Intraoperative Optical Monitoring of Spinal Cord Hemodynamics Using Multiwavelength Imaging System. SENSORS (BASEL, SWITZERLAND) 2022; 22:3840. [PMID: 35632249 PMCID: PMC9146887 DOI: 10.3390/s22103840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 05/13/2022] [Accepted: 05/16/2022] [Indexed: 12/10/2022]
Abstract
The spinal cord is a major structure of the central nervous system allowing, among other things, the transmission of afferent sensory and efferent motor information. During spinal surgery, such as scoliosis correction, this structure can be damaged, resulting in major neurological damage to the patient. To date, there is no direct way to monitor the oxygenation of the spinal cord intraoperatively to reflect its vitality. This is essential information that would allow surgeons to adapt their procedure in case of ischemic suffering of the spinal cord. We report the development of a specific device to monitor the functional status of biological tissues with high resolution. The device, operating with multiple wavelengths, uses Near-InfraRed Spectroscopy (NIRS) in combination with other additional sensors, including ElectroNeuroGraphy (ENG). In this paper, we focused primarily on aspects of the PhotoPlethysmoGram (PPG), emanating from four different light sources to show in real time and record biological signals from the spinal cord in transmission and reflection modes. This multispectral system was successfully tested in in vivo experiments on the spinal cord of a pig for specific medical applications.
Collapse
Affiliation(s)
- Nicolas Mainard
- Department of Pediatric Surgery, Jeanne-de-Flandre Hospital, CHU Lille, Avenue Eugène-Avinée, 59000 Lille, France
- Laboratoire D’Informatique de Paris 6 (LIP6), CNRS UMR7606, Sorbonne Université, 4 Place Jussieu, CEDEX 05, 75252 Paris, France; (S.L.); (J.D.); (K.M.); (S.F.)
| | - Olivier Tsiakaka
- CERVO, Biomedical Microsystems Laboratory, Université Laval, Quebec, QC G1V 0A6, Canada;
| | - Songlin Li
- Laboratoire D’Informatique de Paris 6 (LIP6), CNRS UMR7606, Sorbonne Université, 4 Place Jussieu, CEDEX 05, 75252 Paris, France; (S.L.); (J.D.); (K.M.); (S.F.)
| | - Julien Denoulet
- Laboratoire D’Informatique de Paris 6 (LIP6), CNRS UMR7606, Sorbonne Université, 4 Place Jussieu, CEDEX 05, 75252 Paris, France; (S.L.); (J.D.); (K.M.); (S.F.)
| | - Karim Messaoudene
- Laboratoire D’Informatique de Paris 6 (LIP6), CNRS UMR7606, Sorbonne Université, 4 Place Jussieu, CEDEX 05, 75252 Paris, France; (S.L.); (J.D.); (K.M.); (S.F.)
| | - Raphael Vialle
- Clinical Research Group “RIC” Robotics and Surgical Innovations, GRC-33 Sorbonne University, 26 Avenue du Dr. Arnold Netter, 75012 Paris, France;
| | - Sylvain Feruglio
- Laboratoire D’Informatique de Paris 6 (LIP6), CNRS UMR7606, Sorbonne Université, 4 Place Jussieu, CEDEX 05, 75252 Paris, France; (S.L.); (J.D.); (K.M.); (S.F.)
| |
Collapse
|
4
|
Assessing cerebral blood flow, oxygenation and cytochrome c oxidase stability in preterm infants during the first 3 days after birth. Sci Rep 2022; 12:181. [PMID: 34996949 PMCID: PMC8741949 DOI: 10.1038/s41598-021-03830-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2021] [Accepted: 12/02/2021] [Indexed: 02/07/2023] Open
Abstract
A major concern with preterm birth is the risk of neurodevelopmental disability. Poor cerebral circulation leading to periods of hypoxia is believed to play a significant role in the etiology of preterm brain injury, with the first three days of life considered the period when the brain is most vulnerable. This study focused on monitoring cerebral perfusion and metabolism during the first 72 h after birth in preterm infants weighing less than 1500 g. Brain monitoring was performed by combining hyperspectral near-infrared spectroscopy to assess oxygen saturation and the oxidation state of cytochrome c oxidase (oxCCO), with diffuse correlation spectroscopy to monitor cerebral blood flow (CBF). In seven of eight patients, oxCCO remained independent of CBF, indicating adequate oxygen delivery despite any fluctuations in cerebral hemodynamics. In the remaining infant, a significant correlation between CBF and oxCCO was found during the monitoring periods on days 1 and 3. This infant also had the lowest baseline CBF, suggesting the impact of CBF instabilities on metabolism depends on the level of blood supply to the brain. In summary, this study demonstrated for the first time how continuous perfusion and metabolic monitoring can be achieved, opening the possibility to investigate if CBF/oxCCO monitoring could help identify preterm infants at risk of brain injury.
Collapse
|
5
|
Ioussoufovitch S, Cohen DJF, Milej D, Diop M. Compressed sensing time-resolved spectrometer for quantification of light absorbers in turbid media. BIOMEDICAL OPTICS EXPRESS 2021; 12:6442-6460. [PMID: 34745748 PMCID: PMC8547999 DOI: 10.1364/boe.433427] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 08/20/2021] [Accepted: 09/10/2021] [Indexed: 06/13/2023]
Abstract
Time-resolved (TR) spectroscopy is well-suited to address the challenges of quantifying light absorbers in highly scattering media such as living tissue; however, current TR spectrometers are either based on expensive array detectors or rely on wavelength scanning. Here, we introduce a TR spectrometer architecture based on compressed sensing (CS) and time-correlated single-photon counting. Using both CS and basis scanning, we demonstrate that-in homogeneous and two-layer tissue-mimicking phantoms made of Intralipid and Indocyanine Green-the CS method agrees with or outperforms uncompressed approaches. Further, we illustrate the superior depth sensitivity of TR spectroscopy and highlight the potential of the device to quantify absorption changes in deeper (>1 cm) tissue layers.
Collapse
Affiliation(s)
- Seva Ioussoufovitch
- Western University, Faculty of Engineering, School of Biomedical Engineering, Collaborative Training Program in Musculoskeletal Health Research, Bone & Joint Institute, 1151 Richmond St., London, N6A 5C1, Canada
| | - David Jonathan Fulop Cohen
- Western University, Schulich School of Medicine & Dentistry, Department of Medical Biophysics, 1151 Richmond St., London, N6A 5C1, Canada
| | - Daniel Milej
- Western University, Schulich School of Medicine & Dentistry, Department of Medical Biophysics, 1151 Richmond St., London, N6A 5C1, Canada
- Lawson Health Research Institute, Imaging Program, 268 Grosvenor St., London, N6A 4V2, Canada
| | - Mamadou Diop
- Western University, Faculty of Engineering, School of Biomedical Engineering, Collaborative Training Program in Musculoskeletal Health Research, Bone & Joint Institute, 1151 Richmond St., London, N6A 5C1, Canada
- Western University, Schulich School of Medicine & Dentistry, Department of Medical Biophysics, 1151 Richmond St., London, N6A 5C1, Canada
- Lawson Health Research Institute, Imaging Program, 268 Grosvenor St., London, N6A 4V2, Canada
| |
Collapse
|
6
|
Milej D, Abdalmalak A, Rajaram A, Jhajj A, Owen AM, St. Lawrence K. Incorporating early and late-arriving photons to improve the reconstruction of cerebral hemodynamic responses acquired by time-resolved near-infrared spectroscopy. JOURNAL OF BIOMEDICAL OPTICS 2021; 26:056003. [PMCID: PMC8130006 DOI: 10.1117/1.jbo.26.5.056003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 04/28/2021] [Indexed: 06/14/2023]
Abstract
Significance: Despite its advantages in terms of safety, low cost, and portability, functional near-infrared spectroscopy applications can be challenging due to substantial signal contamination from hemodynamics in the extracerebral layer (ECL). Time-resolved near-infrared spectroscopy (tr NIRS) can improve sensitivity to brain activity but contamination from the ECL remains an issue. This study demonstrates how brain signal isolation can be further improved by applying regression analysis to tr data acquired at a single source–detector distance. Aim: To investigate if regression analysis can be applied to single-channel trNIRS data to further isolate the brain and reduce signal contamination from the ECL. Approach: Appropriate regressors for trNIRS were selected based on simulations, and performance was evaluated by applying the regression technique to oxygenation responses recording during hypercapnia and functional activation. Results: Compared to current methods of enhancing depth sensitivity for trNIRS (i.e., higher statistical moments and late gates), incorporating regression analysis using a signal sensitive to the ECL significantly improved the extraction of cerebral oxygenation signals. In addition, this study demonstrated that regression could be applied to trNIRS data from a single detector using the early arriving photons to capture hemodynamic changes in the ECL. Conclusion: Applying regression analysis to trNIRS metrics with different depth sensitivities improves the characterization of cerebral oxygenation signals.
Collapse
Affiliation(s)
- Daniel Milej
- Lawson Health Research Institute, Imaging Program, London, Ontario, Canada
- Western University, Department of Medical Biophysics, London, Ontario, Canada
| | - Androu Abdalmalak
- Lawson Health Research Institute, Imaging Program, London, Ontario, Canada
- Western University, Department of Medical Biophysics, London, Ontario, Canada
| | - Ajay Rajaram
- Lawson Health Research Institute, Imaging Program, London, Ontario, Canada
- Western University, Department of Medical Biophysics, London, Ontario, Canada
| | - Amandeep Jhajj
- Western University, Department of Medical Biophysics, London, Ontario, Canada
| | - Adrian M. Owen
- Western University, Brain and Mind Institute, London, Ontario, Canada
| | - Keith St. Lawrence
- Lawson Health Research Institute, Imaging Program, London, Ontario, Canada
- Western University, Department of Medical Biophysics, London, Ontario, Canada
| |
Collapse
|
7
|
Kovacsova Z, Bale G, Mitra S, Lange F, Tachtsidis I. Absolute quantification of cerebral tissue oxygen saturation with multidistance broadband NIRS in newborn brain. BIOMEDICAL OPTICS EXPRESS 2021; 12:907-925. [PMID: 33680549 PMCID: PMC7901317 DOI: 10.1364/boe.412088] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 11/27/2020] [Accepted: 11/27/2020] [Indexed: 05/23/2023]
Abstract
Tissue oximetry with near-infrared spectroscopy (NIRS) is a technique for the measurement of absolute tissue oxygen saturation (StO2). Offering a real-time and non-invasive assessment of brain oxygenation and haemodynamics, StO2 has potential to be used for the assessment of newborn brain injury. Multiple algorithms have been developed to measure StO2, however, issues with low measurement accuracy or extracranial tissue signal contamination remain. In this work, we present a novel algorithm to recover StO2 in the neonate, broadband multidistance oximetry (BRUNO), based on a measurement of the gradient of attenuation against distance measured with broadband NIRS. The performance of the algorithm was compared to two other published algorithms, broadband fitting (BF) and spatially resolved spectroscopy (SRS). The median error when recovering StO2 in light transport simulations on a neonatal head mesh was 0.4% with BRUNO, 4.2% with BF and 9.5% with SRS. BRUNO was more sensitive to brain tissue oxygenation changes, shown in layered head model simulations. Comparison of algorithm performance during full oxygenation-deoxygenation cycles in a homogeneous dynamic blood phantom showed significant differences in the dynamic range of the algorithms; BRUNO recovered StO2 over 0-100%, BF over 0-90% and SRS over 39-80%. Recovering StO2 from data collected in a neonate treated at the neonatal intensive care showed different baseline values; mean StO2 was 64.9% with BRUNO, 67.2% with BF and 73.2% with SRS. These findings highlight the effect of StO2 algorithm selection on oxygenation recovery; applying BRUNO in the clinical care setting could reveal further insight into complex haemodynamic processes occurring during neonatal brain injury.
Collapse
Affiliation(s)
- Zuzana Kovacsova
- Department of Medical Physics & Biomedical Engineering, University College London, London, WC1E 6BT, UK
| | - Gemma Bale
- Department of Medical Physics & Biomedical Engineering, University College London, London, WC1E 6BT, UK
- Department of Engineering, University of Cambridge, Cambridge, CB2 1PZ, UK
- Department of Physics, University of Cambridge, Cambridge, CB3 0HE, UK
| | - Subhabrata Mitra
- Institute for Women’s Health, University College London and Neonatal Unit, University College London Hospitals Trust, London, NW1 2BU, UK
| | - Frédéric Lange
- Department of Medical Physics & Biomedical Engineering, University College London, London, WC1E 6BT, UK
| | - Ilias Tachtsidis
- Department of Medical Physics & Biomedical Engineering, University College London, London, WC1E 6BT, UK
| |
Collapse
|
8
|
Rajaram A, Milej D, Suwalski M, Yip LCM, Guo LR, Chu MWA, Chui J, Diop M, Murkin JM, St. Lawrence K. Optical monitoring of cerebral perfusion and metabolism in adults during cardiac surgery with cardiopulmonary bypass. BIOMEDICAL OPTICS EXPRESS 2020; 11:5967-5981. [PMID: 33149999 PMCID: PMC7587277 DOI: 10.1364/boe.404101] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 09/03/2020] [Accepted: 09/03/2020] [Indexed: 05/23/2023]
Abstract
During cardiac surgery with cardiopulmonary bypass (CPB), adequate maintenance of cerebral blood flow (CBF) is vital in preventing postoperative neurological injury - i.e. stroke, delirium, cognitive impairment. Reductions in CBF large enough to impact cerebral energy metabolism can lead to tissue damage and subsequent brain injury. Current methods for neuromonitoring during surgery are limited. This study presents the clinical translation of a hybrid optical neuromonitor for continuous intraoperative monitoring of cerebral perfusion and metabolism in ten patients undergoing non-emergent cardiac surgery with non-pulsatile CPB. The optical system combines broadband near-infrared spectroscopy (B-NIRS) to measure changes in the oxidation state of cytochrome c oxidase (oxCCO) - a direct marker of cellular energy metabolism - and diffuse correlation spectroscopy (DCS) to provide an index of cerebral blood flow (CBFi). As the heart was arrested and the CPB-pump started, increases in CBFi (88.5 ± 125.7%) and significant decreases in oxCCO (-0.5 ± 0.2 µM) were observed; no changes were noted during transitions off CPB. Fifteen hypoperfusion events, defined as large and sustained reductions in CPB-pump flow rate, were identified across all patients and resulted in significant decreases in perfusion and metabolism when mean arterial pressure dropped to 30 mmHg or below. The maximum reduction in cerebral blood flow preceded the corresponding metabolic reduction by 18.2 ± 15.0 s. Optical neuromonitoring provides a safe and non-invasive approach for assessing intraoperative perfusion and metabolism and has potential in guiding patient management to prevent adverse clinical outcomes.
Collapse
Affiliation(s)
- Ajay Rajaram
- Imaging Program, Lawson Health Research Institute, 268 Grosvenor St., London, ON, N6A 4V2, Canada
- Department of Medical Biophysics, Western University, 1151 Richmond St., London, ON, N6A 3K7, Canada
| | - Daniel Milej
- Imaging Program, Lawson Health Research Institute, 268 Grosvenor St., London, ON, N6A 4V2, Canada
| | - Marianne Suwalski
- Imaging Program, Lawson Health Research Institute, 268 Grosvenor St., London, ON, N6A 4V2, Canada
- Department of Medical Biophysics, Western University, 1151 Richmond St., London, ON, N6A 3K7, Canada
| | - Lawrence C. M. Yip
- Imaging Program, Lawson Health Research Institute, 268 Grosvenor St., London, ON, N6A 4V2, Canada
- Department of Medical Biophysics, Western University, 1151 Richmond St., London, ON, N6A 3K7, Canada
| | - Linrui R. Guo
- Division of Cardiac Surgery, London Health Science Centre, 339 Windermere Rd, London, ON, N6A 5A5, Canada
| | - Michael W. A. Chu
- Division of Cardiac Surgery, London Health Science Centre, 339 Windermere Rd, London, ON, N6A 5A5, Canada
| | - Jason Chui
- Department of Anesthesiology and Perioperative Medicine, London Health Science Centre, 339 Windermere Rd, London, ON, N6A 5A5, Canada
| | - Mamadou Diop
- Imaging Program, Lawson Health Research Institute, 268 Grosvenor St., London, ON, N6A 4V2, Canada
- Department of Medical Biophysics, Western University, 1151 Richmond St., London, ON, N6A 3K7, Canada
| | - John M. Murkin
- Department of Anesthesiology and Perioperative Medicine, London Health Science Centre, 339 Windermere Rd, London, ON, N6A 5A5, Canada
| | - Keith St. Lawrence
- Imaging Program, Lawson Health Research Institute, 268 Grosvenor St., London, ON, N6A 4V2, Canada
- Department of Medical Biophysics, Western University, 1151 Richmond St., London, ON, N6A 3K7, Canada
| |
Collapse
|
9
|
Bjorgan A, Randeberg LL. Exploiting scale-invariance: a top layer targeted inverse model for hyperspectral images of wounds. BIOMEDICAL OPTICS EXPRESS 2020; 11:5070-5091. [PMID: 33014601 PMCID: PMC7510863 DOI: 10.1364/boe.399636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 07/15/2020] [Accepted: 07/28/2020] [Indexed: 05/10/2023]
Abstract
Detection of re-epithelialization in wound healing is important, but challenging. Hyperspectral imaging can be used for non-destructive characterization, but efficient techniques are needed to extract and interpret the information. An inverse photon transport model suitable for characterization of re-epithelialization is validated and explored in this study. It exploits scale-invariance to enable fitting of the epidermal skin layer only. Monte Carlo simulations indicate that the fitted layer transmittance and reflectance spectra are unique, and that there exists an infinite number of coupled parameter solutions. The method is used to explain the optical behavior of and detect re-epithelialization in an in vitro wound model.
Collapse
|
10
|
Milej D, Shahid M, Abdalmalak A, Rajaram A, Diop M, St. Lawrence K. Characterizing dynamic cerebral vascular reactivity using a hybrid system combining time-resolved near-infrared and diffuse correlation spectroscopy. BIOMEDICAL OPTICS EXPRESS 2020; 11:4571-4585. [PMID: 32923065 PMCID: PMC7449704 DOI: 10.1364/boe.392113] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 04/28/2020] [Accepted: 05/12/2020] [Indexed: 05/09/2023]
Abstract
This study presents the characterization of dynamic cerebrovascular reactivity (CVR) in healthy adults by a hybrid optical system combining time-resolved (TR) near-infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS). Blood flow and oxygenation (oxy- and deoxy-hemoglobin) responses to a step hypercapnic challenge were recorded to characterize dynamic and static components of CVR. Data were acquired at short and long source-detector separations (r SD) to assess the impact of scalp hemodynamics, and moment analysis applied to the TR-NIRS to further enhance the sensitivity to the brain. Comparing blood flow and oxygenation responses acquired at short and long r SD demonstrated that scalp contamination distorted the CVR time courses, particularly for oxyhemoglobin. This effect was significantly diminished by the greater depth sensitivity of TR NIRS and less evident in the DCS data due to the higher blood flow in the brain compared to the scalp. The reactivity speed was similar for blood flow and oxygenation in the healthy brain. Given the ease-of-use, portability, and non-invasiveness of this hybrid approach, it is well suited to investigate if the temporal relationship between CBF and oxygenation is altered by factors such as age and cerebrovascular disease.
Collapse
Affiliation(s)
- Daniel Milej
- Imaging Program, Lawson Health Research Institute, London, Ontario, N6A 4V2, Canada
- Department of Medical Biophysics, Western University, London, Ontario, N6A 5C1, Canada
| | - Marwan Shahid
- Imaging Program, Lawson Health Research Institute, London, Ontario, N6A 4V2, Canada
- Department of Medical Biophysics, Western University, London, Ontario, N6A 5C1, Canada
| | - Androu Abdalmalak
- Imaging Program, Lawson Health Research Institute, London, Ontario, N6A 4V2, Canada
- Department of Medical Biophysics, Western University, London, Ontario, N6A 5C1, Canada
| | - Ajay Rajaram
- Imaging Program, Lawson Health Research Institute, London, Ontario, N6A 4V2, Canada
- Department of Medical Biophysics, Western University, London, Ontario, N6A 5C1, Canada
| | - Mamadou Diop
- Imaging Program, Lawson Health Research Institute, London, Ontario, N6A 4V2, Canada
- Department of Medical Biophysics, Western University, London, Ontario, N6A 5C1, Canada
| | - Keith St. Lawrence
- Imaging Program, Lawson Health Research Institute, London, Ontario, N6A 4V2, Canada
- Department of Medical Biophysics, Western University, London, Ontario, N6A 5C1, Canada
| |
Collapse
|
11
|
Rajaram A, Yip LCM, Milej D, Suwalski M, Kewin M, Lo M, Carson JJL, Han V, Bhattacharya S, Diop M, de Ribaupierre S, St. Lawrence K. Perfusion and Metabolic Neuromonitoring during Ventricular Taps in Infants with Post-Hemorrhagic Ventricular Dilatation. Brain Sci 2020; 10:E452. [PMID: 32679665 PMCID: PMC7407524 DOI: 10.3390/brainsci10070452] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 07/03/2020] [Accepted: 07/13/2020] [Indexed: 01/08/2023] Open
Abstract
Post-hemorrhagic ventricular dilatation (PHVD) is characterized by a build-up of cerebral spinal fluid (CSF) in the ventricles, which increases intracranial pressure and compresses brain tissue. Clinical interventions (i.e., ventricular taps, VT) work to mitigate these complications through CSF drainage; however, the timing of these procedures remains imprecise. This study presents Neonatal NeuroMonitor (NNeMo), a portable optical device that combines broadband near-infrared spectroscopy (B-NIRS) and diffuse correlation spectroscopy (DCS) to provide simultaneous assessments of cerebral blood flow (CBF), tissue saturation (StO2), and the oxidation state of cytochrome c oxidase (oxCCO). In this study, NNeMo was used to monitor cerebral hemodynamics and metabolism in PHVD patients selected for a VT. Across multiple VTs in four patients, no significant changes were found in any of the three parameters: CBF increased by 14.6 ± 37.6% (p = 0.09), StO2 by 1.9 ± 4.9% (p = 0.2), and oxCCO by 0.4 ± 0.6 µM (p = 0.09). However, removing outliers resulted in significant, but small, increases in CBF (6.0 ± 7.7%) and oxCCO (0.1 ± 0.1 µM). The results of this study demonstrate NNeMo's ability to provide safe, non-invasive measurements of cerebral perfusion and metabolism for neuromonitoring applications in the neonatal intensive care unit.
Collapse
Affiliation(s)
- Ajay Rajaram
- Imaging Program, Lawson Health Research Institute, London, ON N6A 4V2, Canada; (L.C.M.Y.); (D.M.); (M.S.); (M.K.); (M.L.); (J.J.L.C.); (M.D.); (K.S.L.)
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, ON N6A 3K7, Canada;
| | - Lawrence C. M. Yip
- Imaging Program, Lawson Health Research Institute, London, ON N6A 4V2, Canada; (L.C.M.Y.); (D.M.); (M.S.); (M.K.); (M.L.); (J.J.L.C.); (M.D.); (K.S.L.)
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, ON N6A 3K7, Canada;
| | - Daniel Milej
- Imaging Program, Lawson Health Research Institute, London, ON N6A 4V2, Canada; (L.C.M.Y.); (D.M.); (M.S.); (M.K.); (M.L.); (J.J.L.C.); (M.D.); (K.S.L.)
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, ON N6A 3K7, Canada;
| | - Marianne Suwalski
- Imaging Program, Lawson Health Research Institute, London, ON N6A 4V2, Canada; (L.C.M.Y.); (D.M.); (M.S.); (M.K.); (M.L.); (J.J.L.C.); (M.D.); (K.S.L.)
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, ON N6A 3K7, Canada;
| | - Matthew Kewin
- Imaging Program, Lawson Health Research Institute, London, ON N6A 4V2, Canada; (L.C.M.Y.); (D.M.); (M.S.); (M.K.); (M.L.); (J.J.L.C.); (M.D.); (K.S.L.)
| | - Marcus Lo
- Imaging Program, Lawson Health Research Institute, London, ON N6A 4V2, Canada; (L.C.M.Y.); (D.M.); (M.S.); (M.K.); (M.L.); (J.J.L.C.); (M.D.); (K.S.L.)
| | - Jeffrey J. L. Carson
- Imaging Program, Lawson Health Research Institute, London, ON N6A 4V2, Canada; (L.C.M.Y.); (D.M.); (M.S.); (M.K.); (M.L.); (J.J.L.C.); (M.D.); (K.S.L.)
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, ON N6A 3K7, Canada;
| | - Victor Han
- Division of Neonatal-Perinatal Medicine, Department of Pediatrics, London Health Sciences Centre, London, ON N6A 3K7, Canada; (V.H.); (S.B.)
| | - Soume Bhattacharya
- Division of Neonatal-Perinatal Medicine, Department of Pediatrics, London Health Sciences Centre, London, ON N6A 3K7, Canada; (V.H.); (S.B.)
| | - Mamadou Diop
- Imaging Program, Lawson Health Research Institute, London, ON N6A 4V2, Canada; (L.C.M.Y.); (D.M.); (M.S.); (M.K.); (M.L.); (J.J.L.C.); (M.D.); (K.S.L.)
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, ON N6A 3K7, Canada;
| | - Sandrine de Ribaupierre
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, ON N6A 3K7, Canada;
- Department of Clinical Neurological Sciences, London Health Sciences Centre, London, ON N6A 5W9, Canada
| | - Keith St. Lawrence
- Imaging Program, Lawson Health Research Institute, London, ON N6A 4V2, Canada; (L.C.M.Y.); (D.M.); (M.S.); (M.K.); (M.L.); (J.J.L.C.); (M.D.); (K.S.L.)
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, ON N6A 3K7, Canada;
| |
Collapse
|
12
|
Abdalmalak A, Milej D, Yip LCM, Khan AR, Diop M, Owen AM, St Lawrence K. Assessing Time-Resolved fNIRS for Brain-Computer Interface Applications of Mental Communication. Front Neurosci 2020; 14:105. [PMID: 32132894 PMCID: PMC7040089 DOI: 10.3389/fnins.2020.00105] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 01/27/2020] [Indexed: 12/13/2022] Open
Abstract
Brain-computer interfaces (BCIs) are becoming increasingly popular as a tool to improve the quality of life of patients with disabilities. Recently, time-resolved functional near-infrared spectroscopy (TR-fNIRS) based BCIs are gaining traction because of their enhanced depth sensitivity leading to lower signal contamination from the extracerebral layers. This study presents the first account of TR-fNIRS based BCI for “mental communication” on healthy participants. Twenty-one (21) participants were recruited and were repeatedly asked a series of questions where they were instructed to imagine playing tennis for “yes” and to stay relaxed for “no.” The change in the mean time-of-flight of photons was used to calculate the change in concentrations of oxy- and deoxyhemoglobin since it provides a good compromise between depth sensitivity and signal-to-noise ratio. Features were extracted from the average oxyhemoglobin signals to classify them as “yes” or “no” responses. Linear-discriminant analysis (LDA) and support vector machine (SVM) classifiers were used to classify the responses using the leave-one-out cross-validation method. The overall accuracies achieved for all participants were 75% and 76%, using LDA and SVM, respectively. The results also reveal that there is no significant difference in accuracy between questions. In addition, physiological parameters [heart rate (HR) and mean arterial pressure (MAP)] were recorded on seven of the 21 participants during motor imagery (MI) and rest to investigate changes in these parameters between conditions. No significant difference in these parameters was found between conditions. These findings suggest that TR-fNIRS could be suitable as a BCI for patients with brain injuries.
Collapse
Affiliation(s)
- Androu Abdalmalak
- Department of Medical Biophysics, Western University, London, ON, Canada.,Imaging Program, Lawson Health Research Institute, London, ON, Canada
| | - Daniel Milej
- Department of Medical Biophysics, Western University, London, ON, Canada.,Imaging Program, Lawson Health Research Institute, London, ON, Canada
| | - Lawrence C M Yip
- Department of Medical Biophysics, Western University, London, ON, Canada.,Imaging Program, Lawson Health Research Institute, London, ON, Canada
| | - Ali R Khan
- Department of Medical Biophysics, Western University, London, ON, Canada.,Imaging Research Laboratories, Robarts Research Institute, London, ON, Canada
| | - Mamadou Diop
- Department of Medical Biophysics, Western University, London, ON, Canada.,Imaging Program, Lawson Health Research Institute, London, ON, Canada
| | - Adrian M Owen
- Brain and Mind Institute, Western University, London, ON, Canada
| | - Keith St Lawrence
- Department of Medical Biophysics, Western University, London, ON, Canada.,Imaging Program, Lawson Health Research Institute, London, ON, Canada
| |
Collapse
|