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Sudakou A, Wabnitz H, Liemert A, Wolf M, Liebert A. Two-layered blood-lipid phantom and method to determine absorption and oxygenation employing changes in moments of DTOFs. BIOMEDICAL OPTICS EXPRESS 2023; 14:3506-3531. [PMID: 37497481 PMCID: PMC10368065 DOI: 10.1364/boe.492168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 05/29/2023] [Accepted: 05/29/2023] [Indexed: 07/28/2023]
Abstract
Near-infrared spectroscopy (NIRS) is an established technique for measuring tissue oxygen saturation (StO2), which is of high clinical value. For tissues that have layered structures, it is challenging but clinically relevant to obtain StO2 of the different layers, e.g. brain and scalp. For this aim, we present a new method of data analysis for time-domain NIRS (TD-NIRS) and a new two-layered blood-lipid phantom. The new analysis method enables accurate determination of even large changes of the absorption coefficient (Δµa) in multiple layers. By adding Δµa to the baseline µa, this method provides absolute µa and hence StO2 in multiple layers. The method utilizes (i) changes in statistical moments of the distributions of times of flight of photons (DTOFs), (ii) an analytical solution of the diffusion equation for an N-layered medium, (iii) and the Levenberg-Marquardt algorithm (LMA) to determine Δµa in multiple layers from the changes in moments. The method is suitable for NIRS tissue oximetry (relying on µa) as well as functional NIRS (fNIRS) applications (relying on Δµa). Experiments were conducted on a new phantom, which enabled us to simulate dynamic StO2 changes in two layers for the first time. Two separate compartments, which mimic superficial and deep layers, hold blood-lipid mixtures that can be deoxygenated (using yeast) and oxygenated (by bubbling oxygen) independently. Simultaneous NIRS measurements can be performed on the two-layered medium (variable superficial layer thickness, L), the deep (homogeneous), and/or the superficial (homogeneous). In two experiments involving ink, we increased the nominal µa in one of two compartments from 0.05 to 0.25 cm-1, L set to 14.5 mm. In three experiments involving blood (L set to 12, 15, or 17 mm), we used a protocol consisting of six deoxygenation cycles. A state-of-the-art multi-wavelength TD-NIRS system measured simultaneously on the two-layered medium, as well as on the deep compartment for a reference. The new method accurately determined µa (and hence StO2) in both compartments. The method is a significant progress in overcoming the contamination from the superficial layer, which is beneficial for NIRS and fNIRS applications, and may improve the determination of StO2 in the brain from measurements on the head. The advanced phantom may assist in the ongoing effort towards more realistic standardized performance tests in NIRS tissue oximetry. Data and MATLAB codes used in this study were made publicly available.
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Affiliation(s)
- Aleh Sudakou
- Nałęcz Institute of Biocybernetics and Biomedical Engineering Polish Academy of Sciences, Warsaw, Poland
| | - Heidrun Wabnitz
- Physikalisch-Technische Bundesanstalt (PTB), Berlin, Germany
| | - André Liemert
- Institut für Lasertechnologien in der Medizin und Meßtechnik an der Universität Ulm, Germany
| | - Martin Wolf
- Department of Neonatology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Adam Liebert
- Nałęcz Institute of Biocybernetics and Biomedical Engineering Polish Academy of Sciences, Warsaw, Poland
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2
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Wabnitz H, Contini D, Spinelli L, Torricelli A, Liebert A. Depth-selective data analysis for time-domain fNIRS: moments vs. time windows. BIOMEDICAL OPTICS EXPRESS 2020; 11:4224-4243. [PMID: 32923038 PMCID: PMC7449728 DOI: 10.1364/boe.396585] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 06/20/2020] [Accepted: 06/22/2020] [Indexed: 05/10/2023]
Abstract
Time-domain measurements facilitate the elimination of the influence of extracerebral, systemic effects, a key problem in functional near-infrared spectroscopy (fNIRS) of the adult human brain. The analysis of measured time-of-flight distributions of photons often relies on moments or time windows. However, a systematic and quantitative characterization of the performance of these measurands is still lacking. Based on perturbation simulations for small localized absorption changes, we compared spatial sensitivity profiles and depth selectivity for moments (integral, mean time of flight and variance), photon counts in time windows and their ratios for different time windows. The influence of the instrument response function (IRF) was investigated for all measurands and for various source-detector separations. Variance exhibits the highest depth selectivity among the moments. Ratios of photon counts in different late time windows can achieve even higher selectivity. An advantage of moments is their robustness against the shape of the IRF and instrumental drifts.
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Affiliation(s)
- Heidrun Wabnitz
- Physikalisch-Technische Bundesanstalt (PTB), Abbestraße 2-12, 10587 Berlin, Germany
| | - Davide Contini
- Politecnico di Milano, Dipartimento di Fisica, Piazza Leonardo da Vinci 32, 20133 Milan, Italy
| | - Lorenzo Spinelli
- Istituto di Fotonica e Nanotecnologie, Consiglio Nazionale delle Ricerche, Piazza Leonardo da Vinci 32, 20133 Milan, Italy
| | - Alessandro Torricelli
- Politecnico di Milano, Dipartimento di Fisica, Piazza Leonardo da Vinci 32, 20133 Milan, Italy
- Istituto di Fotonica e Nanotecnologie, Consiglio Nazionale delle Ricerche, Piazza Leonardo da Vinci 32, 20133 Milan, Italy
| | - Adam Liebert
- Nalecz Institute of Biocybernetics and Biomedical Engineering, Trojdena 4, 02-109 Warsaw, Poland
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3
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Baez GR, García H, Grosenick D, Wabnitz H. Implementation of the extended Kalman filter for determining the optical and geometrical properties of turbid layered media by time-resolved single distance measurements. BIOMEDICAL OPTICS EXPRESS 2020; 11:251-266. [PMID: 32010514 PMCID: PMC6968768 DOI: 10.1364/boe.11.000251] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 11/27/2019] [Accepted: 11/27/2019] [Indexed: 05/20/2023]
Abstract
In this article we propose an implementation of the extended Kalman filter (EKF) for the retrieval of optical and geometrical properties in two-layered turbid media assuming a dynamic setting, where absorption of each layer was changed in different steps. Prior works implemented the EKF in frequency-domain with several pairs of light sources and detectors and for static parameters estimation problems. Here we explore the use of the EKF in single distance, time-domain measurements, together with a corresponding forward model. Results show good agreement between retrieved and nominal values, with rather narrow analytical credibility intervals, indicating that the recovery process has low uncertainty, especially for the absorption coefficients.
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Affiliation(s)
- Guido R. Baez
- Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires (CIFICEN, UNCPBA - CICPBA - CONICET) Pinto 399, B7000GHG - Tandil, Buenos Aires, Argentina
- PLADEMA, FCEx - UNCPBA, Pinto 399, B7000GHG - Tandil, Buenos Aires, Argentina
| | - Héctor García
- Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires (CIFICEN, UNCPBA - CICPBA - CONICET) Pinto 399, B7000GHG - Tandil, Buenos Aires, Argentina
- Physikalisch-Technische Bundesanstalt (PTB), Abbestraβe 2-12, 10587, Berlin, Germany
| | - Dirk Grosenick
- Physikalisch-Technische Bundesanstalt (PTB), Abbestraβe 2-12, 10587, Berlin, Germany
| | - Heidrun Wabnitz
- Physikalisch-Technische Bundesanstalt (PTB), Abbestraβe 2-12, 10587, Berlin, Germany
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Almajidy RK, Mankodiya K, Abtahi M, Hofmann UG. A Newcomer's Guide to Functional Near Infrared Spectroscopy Experiments. IEEE Rev Biomed Eng 2019; 13:292-308. [PMID: 31634142 DOI: 10.1109/rbme.2019.2944351] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
This review presents a practical primer for functional near-infrared spectroscopy (fNIRS) with respect to technology, experimentation, and analysis software. Its purpose is to jump-start interested practitioners considering utilizing a non-invasive, versatile, nevertheless challenging window into the brain using optical methods. We briefly recapitulate relevant anatomical and optical foundations and give a short historical overview. We describe competing types of illumination (trans-illumination, reflectance, and differential reflectance) and data collection methods (continuous wave, time domain and frequency domain). Basic components (light sources, detection, and recording components) of fNIRS systems are presented. Advantages and limitations of fNIRS techniques are offered, followed by a list of very practical recommendations for its use. A variety of experimental and clinical studies with fNIRS are sampled, shedding light on many brain-related ailments. Finally, we describe and discuss a number of freely available analysis and presentation packages suited for data analysis. In conclusion, we recommend fNIRS due to its ever-growing body of clinical applications, state-of-the-art neuroimaging technique and manageable hardware requirements. It can be safely concluded that fNIRS adds a new arrow to the quiver of neuro-medical examinations due to both its great versatility and limited costs.
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5
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Sudakou A, Wojtkiewicz S, Lange F, Gerega A, Sawosz P, Tachtsidis I, Liebert A. Depth-resolved assessment of changes in concentration of chromophores using time-resolved near-infrared spectroscopy: estimation of cytochrome-c-oxidase uncertainty by Monte Carlo simulations. BIOMEDICAL OPTICS EXPRESS 2019; 10:4621-4635. [PMID: 31565513 PMCID: PMC6757481 DOI: 10.1364/boe.10.004621] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 08/05/2019] [Accepted: 08/06/2019] [Indexed: 06/10/2023]
Abstract
Time-resolved near-infrared spectroscopy (TR-NIRS) measurements can be used to recover changes in concentrations of tissue constituents ( Δ C ) by applying the moments method and the Beer-Lambert law. In this work we carried out the error propagation analysis allowing to calculate the standard deviations of uncertainty in estimation of the Δ C . Here, we show the process of choosing wavelengths for the evaluation of hemodynamic (oxy-, deoxyhemoglobin) and metabolic (cytochrome-c-oxidase (CCO)) responses within the brain tissue as measured with an in-house developed TR-NIRS multi-wavelength system, which measures at 16 consecutive wavelengths separated by 12.5 nm and placed between 650 and 950 nm. Data generated with Monte Carlo simulations on three-layered model (scalp, skull, brain) for wavelengths range from 650 to 950 nm were used to carry out the error propagation analysis for varying choices of wavelengths. For a detector with a spectrally uniform responsivity, the minimal standard deviation of the estimated changes in CCO within the brain layer, σ Δ C CCO brain = 0.40 µM, was observed for the 16 consecutive wavelengths from 725 to 912.5 nm. For realistic a detector model, i.e. the spectral responsivity characteristic is considered, the minimum, σ Δ C CCO brain = 0.47 µM, was observed at the 16 consecutive wavelengths from 688 to 875 nm. We introduce the method of applying the error propagation analysis to data as measured with spectral TR-NIRS systems to calculate uncertainty of recovery of tissue constituents concentrations.
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Affiliation(s)
- Aleh Sudakou
- Nalecz Institute of Biocybernetics and Biomedical Engineering Polish Academy of Sciences, Trojdena 4, 02-109 Warsaw, Poland
| | - Stanislaw Wojtkiewicz
- Nalecz Institute of Biocybernetics and Biomedical Engineering Polish Academy of Sciences, Trojdena 4, 02-109 Warsaw, Poland
- School of Computer Science, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom
| | - Frédéric Lange
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, United Kingdom
| | - Anna Gerega
- Nalecz Institute of Biocybernetics and Biomedical Engineering Polish Academy of Sciences, Trojdena 4, 02-109 Warsaw, Poland
| | - Piotr Sawosz
- Nalecz Institute of Biocybernetics and Biomedical Engineering Polish Academy of Sciences, Trojdena 4, 02-109 Warsaw, Poland
| | - Ilias Tachtsidis
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, United Kingdom
| | - Adam Liebert
- Nalecz Institute of Biocybernetics and Biomedical Engineering Polish Academy of Sciences, Trojdena 4, 02-109 Warsaw, Poland
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Grosenick D, Wabnitz H, Macdonald R. Diffuse near-infrared imaging of tissue with picosecond time resolution. ACTA ACUST UNITED AC 2019; 63:511-518. [PMID: 29494335 DOI: 10.1515/bmt-2017-0067] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 12/04/2017] [Indexed: 02/02/2023]
Abstract
Optical imaging of biological tissue in vivo at multiple wavelengths in the near-infrared (NIR) spectral range can be achieved with picosecond time resolution at high sensitivity by time-correlated single photon counting. Measuring and analyzing the distribution of times of flight of photons randomly propagated through the tissue has been applied for diffuse optical imaging and spectroscopy, e.g. of human breast tissue and of the brain. In this article, we review the main features and the potential of NIR multispectral imaging with picosecond time resolution and illustrate them by exemplar applications in these fields. In particular, we discuss the experimental methods developed at the Physikalisch-Technische Bundesanstalt (PTB) to record optical mammograms and to quantify the absorption and scattering properties from which hemoglobin concentration and oxygen saturation of healthy and diseased breast tissue have been derived by combining picosecond time-domain and spectral information. Furthermore, optical images of functional brain activation were obtained by a non-contact scanning device exploiting the null source-detector separation approach which takes advantage of the picosecond time resolution as well. The recorded time traces of changes in the oxy- and deoxyhemoglobin concentrations during a motor stimulation investigation show a localized response from the brain.
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Affiliation(s)
- Dirk Grosenick
- Physikalisch-Technische Bundesanstalt (PTB), Abbestraße 2-12, 10587 Berlin, Germany, Phone: +49 30 3481-7302, Fax: +49 30 3481-7505
| | - Heidrun Wabnitz
- Physikalisch-Technische Bundesanstalt (PTB), 10587 Berlin, Germany
| | - Rainer Macdonald
- Physikalisch-Technische Bundesanstalt (PTB), 10587 Berlin, Germany
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7
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He L, Baker WB, Milej D, Kavuri VC, Mesquita RC, Busch DR, Abramson K, Jiang JY, Diop M, St. Lawrence K, Amendolia O, Quattrone F, Balu R, Kofke WA, Yodh AG. Noninvasive continuous optical monitoring of absolute cerebral blood flow in critically ill adults. NEUROPHOTONICS 2018; 5:045006. [PMID: 30480039 PMCID: PMC6251207 DOI: 10.1117/1.nph.5.4.045006] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2018] [Accepted: 10/29/2018] [Indexed: 05/18/2023]
Abstract
We investigate a scheme for noninvasive continuous monitoring of absolute cerebral blood flow (CBF) in adult human patients based on a combination of time-resolved dynamic contrast-enhanced near-infrared spectroscopy (DCE-NIRS) and diffuse correlation spectroscopy (DCS) with semi-infinite head model of photon propogation. Continuous CBF is obtained via calibration of the DCS blood flow index (BFI) with absolute CBF obtained by intermittent intravenous injections of the optical contrast agent indocyanine green. A calibration coefficient ( γ ) for the CBF is thus determined, permitting conversion of DCS BFI to absolute blood flow units at all other times. A study of patients with acute brain injury ( N = 7 ) is carried out to ascertain the stability of γ . The patient-averaged DCS calibration coefficient across multiple monitoring days and multiple patients was determined, and good agreement between the two calibration coefficients measured at different times during single monitoring days was found. The patient-averaged calibration coefficient of 1.24 × 10 9 ( mL / 100 g / min ) / ( cm 2 / s ) was applied to previously measured DCS BFI from similar brain-injured patients; in this case, absolute CBF was underestimated compared with XeCT, an effect we show is primarily due to use of semi-infinite homogeneous models of the head.
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Affiliation(s)
- Lian He
- University of Pennsylvania, Department of Physics and Astronomy, Philadelphia, Pennsylvania, United States
- Address all correspondence to: Lian He, E-mail:
| | - Wesley B. Baker
- University of Pennsylvania, Department of Physics and Astronomy, Philadelphia, Pennsylvania, United States
- University of Pennsylvania, Department of Anesthesiology and Critical Care, Perelman School of Medicine, Philadelphia, Pennsylvania, United States
| | - Daniel Milej
- Western University, Department of Medical Biophysics, London, Ontario, Canada
- Lawson Health Research Institute, Imaging Division, London, Ontario, Canada
| | - Venkaiah C. Kavuri
- University of Pennsylvania, Department of Physics and Astronomy, Philadelphia, Pennsylvania, United States
| | | | - David R. Busch
- University of Texas Southwestern, Department of Neurology and Neurotherapeutics, Dallas, Texas, United States
- University of Texas Southwestern, Department of Anesthesiology and Pain Management, Dallas, Texas, United States
| | - Kenneth Abramson
- University of Pennsylvania, Department of Physics and Astronomy, Philadelphia, Pennsylvania, United States
| | - Jane Y. Jiang
- University of Pennsylvania, Department of Physics and Astronomy, Philadelphia, Pennsylvania, United States
| | - Mamadou Diop
- Western University, Department of Medical Biophysics, London, Ontario, Canada
- Lawson Health Research Institute, Imaging Division, London, Ontario, Canada
| | - Keith St. Lawrence
- Western University, Department of Medical Biophysics, London, Ontario, Canada
- Lawson Health Research Institute, Imaging Division, London, Ontario, Canada
| | - Olivia Amendolia
- University of Pennsylvania, Department of Neurosurgery, Perelman School of Medicine, Philadelphia, Pennsylvania, United States
| | - Francis Quattrone
- University of Pennsylvania, Department of Neurosurgery, Perelman School of Medicine, Philadelphia, Pennsylvania, United States
| | - Ramani Balu
- University of Pennsylvania, Department of Neurosurgery, Perelman School of Medicine, Philadelphia, Pennsylvania, United States
- University of Pennsylvania, Department of Neurology, Perelman School of Medicine, Philadelphia, Pennsylvania, United States
| | - W. Andrew Kofke
- University of Pennsylvania, Department of Anesthesiology and Critical Care, Perelman School of Medicine, Philadelphia, Pennsylvania, United States
- University of Pennsylvania, Department of Neurosurgery, Perelman School of Medicine, Philadelphia, Pennsylvania, United States
| | - Arjun G. Yodh
- University of Pennsylvania, Department of Physics and Astronomy, Philadelphia, Pennsylvania, United States
- University of Pennsylvania, Department of Anesthesiology and Critical Care, Perelman School of Medicine, Philadelphia, Pennsylvania, United States
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Lange F, Peyrin F, Montcel B. Broadband time-resolved multi-channel functional near-infrared spectroscopy system to monitor in vivo physiological changes of human brain activity. APPLIED OPTICS 2018; 57:6417-6429. [PMID: 30117872 DOI: 10.1364/ao.57.006417] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Accepted: 06/21/2018] [Indexed: 05/18/2023]
Abstract
We have developed a broadband time-resolved multi-channel near-infrared spectroscopy system that can monitor the physiological responses of the adult human brain. This system is composed of a supercontinuum laser for the source part and of an intensified charge-coupled device camera coupled with an imaging spectrometer for the detection part. It allows the detection of the spectral, from 600 to 900 nm, and spatial dimensions as well as the arrival time of photon information simultaneously. We describe the setup and its characterization in terms of temporal instrument response function, wavelength sensitivity, and stability. The ability of the system to detect the hemodynamic response is then demonstrated. First, an in vivo experiment on an adult volunteer was performed to monitor the response in the arm during a cuff occlusion. Second, the response in the brain during a cognitive task was monitored on a group of five healthy volunteers. Moreover, looking at the response at different time windows, we could monitor the hemodynamic response in depth, enhancing the detection of the cortical activation. Those first results demonstrate the ability of our system to discriminate between the responses of superficial and deep tissues, addressing an important issue in functional near-infrared spectroscopy.
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Nasseri N, Kleiser S, Ostojic D, Karen T, Wolf M. Quantifying the effect of adipose tissue in muscle oximetry by near infrared spectroscopy. BIOMEDICAL OPTICS EXPRESS 2016; 7:4605-4619. [PMID: 27895999 PMCID: PMC5119599 DOI: 10.1364/boe.7.004605] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Revised: 09/11/2016] [Accepted: 09/23/2016] [Indexed: 05/18/2023]
Abstract
Change of muscle tissue oxygen saturation (StO2), due to exercise, measured by near infrared spectroscopy (NIRS) is known to be lower for subjects with higher adipose tissue thickness. This is most likely not physiological but caused by the superficial fat and adipose tissue. In this paper we assessed, in vitro, the influence of adipose tissue thickness on muscle StO2, measured by NIRS oximeters. We measured StO2 of a liquid phantom by 3 continuous wave (CW) oximeters (Sensmart Model X-100 Universal Oximetry System, INVOS 5100C, and OxyPrem v1.3), as well as a frequency-domain oximeter, OxiplexTS, through superficial layers with 4 different thicknesses. Later, we employed the results to calibrate OxyPrem v1.3 for adipose tissue thickness in-vivo.
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Affiliation(s)
- Nassim Nasseri
- Biomedical Optics Research Laboratory, Department of Neonatology, University Hospital Zurich, Zurich,
Switzerland
- equal contribution
| | - Stefan Kleiser
- Biomedical Optics Research Laboratory, Department of Neonatology, University Hospital Zurich, Zurich,
Switzerland
- equal contribution
| | - Daniel Ostojic
- Biomedical Optics Research Laboratory, Department of Neonatology, University Hospital Zurich, Zurich,
Switzerland
| | - Tanja Karen
- Department of Neonatology, University Hospital Zurich, Zurich,
Switzerland
| | - Martin Wolf
- Biomedical Optics Research Laboratory, Department of Neonatology, University Hospital Zurich, Zurich,
Switzerland
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Tachtsidis I, Scholkmann F. False positives and false negatives in functional near-infrared spectroscopy: issues, challenges, and the way forward. NEUROPHOTONICS 2016; 3:031405. [PMID: 27054143 PMCID: PMC4791590 DOI: 10.1117/1.nph.3.3.031405] [Citation(s) in RCA: 277] [Impact Index Per Article: 34.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 02/05/2016] [Indexed: 05/20/2023]
Abstract
We highlight a significant problem that needs to be considered and addressed when performing functional near-infrared spectroscopy (fNIRS) studies, namely the possibility of inadvertently measuring fNIRS hemodynamic responses that are not due to neurovascular coupling. These can be misinterpreted as brain activity, i.e., "false positives" (errors caused by wrongly assigning a detected hemodynamic response to functional brain activity), or mask brain activity, i.e., "false negatives" (errors caused by wrongly assigning a not observed hemodynamic response in the presence of functional brain activity). Here, we summarize the possible physiological origins of these issues and suggest ways to avoid and remove them.
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Affiliation(s)
- Ilias Tachtsidis
- University College London, Department of Medical Physics and Biomedical Engineering, Gower Street, Malet Place Engineering Building, WC1E 6BT, London, United Kingdom
| | - Felix Scholkmann
- University Hospital Zurich, University of Zurich, Department of Neonatology, Biomedical Optics Research Laboratory, Frauenklinikstr. 10, 8091 Zurich, Switzerland
- Address all correspondence to: Felix Scholkmann, E-mail:
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11
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Tachtsidis I, Scholkmann F. False positives and false negatives in functional near-infrared spectroscopy: issues, challenges, and the way forward. NEUROPHOTONICS 2016. [PMID: 27054143 DOI: 10.1117/1.nph.3.3.030401] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
We highlight a significant problem that needs to be considered and addressed when performing functional near-infrared spectroscopy (fNIRS) studies, namely the possibility of inadvertently measuring fNIRS hemodynamic responses that are not due to neurovascular coupling. These can be misinterpreted as brain activity, i.e., "false positives" (errors caused by wrongly assigning a detected hemodynamic response to functional brain activity), or mask brain activity, i.e., "false negatives" (errors caused by wrongly assigning a not observed hemodynamic response in the presence of functional brain activity). Here, we summarize the possible physiological origins of these issues and suggest ways to avoid and remove them.
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Affiliation(s)
- Ilias Tachtsidis
- University College London , Department of Medical Physics and Biomedical Engineering, Gower Street, Malet Place Engineering Building, WC1E 6BT, London, United Kingdom
| | - Felix Scholkmann
- University Hospital Zurich, University of Zurich , Department of Neonatology, Biomedical Optics Research Laboratory, Frauenklinikstr. 10, 8091 Zurich, Switzerland
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12
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Martelli F, Del Bianco S, Spinelli L, Cavalieri S, Di Ninni P, Binzoni T, Jelzow A, Macdonald R, Wabnitz H. Optimal estimation reconstruction of the optical properties of a two-layered tissue phantom from time-resolved single-distance measurements. JOURNAL OF BIOMEDICAL OPTICS 2015; 20:115001. [PMID: 26524677 DOI: 10.1117/1.jbo.20.11.115001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 09/25/2015] [Indexed: 05/02/2023]
Abstract
In this work, we have tested the optimal estimation (OE) algorithm for the reconstruction of the optical properties of a two-layered liquid tissue phantom from time-resolved single-distance measurements. The OE allows a priori information, in particular on the range of variation of fit parameters, to be included. The purpose of the present investigations was to compare the performance of OE with the Levenberg–Marquardt method for a geometry and real experimental conditions typically used to reconstruct the optical properties of biological tissues such as muscle and brain. The absorption coefficient of the layers was varied in a range of values typical for biological tissues. The reconstructions performed demonstrate the substantial improvements achievable with the OE provided a priori information is available. We note the extreme reliability, robustness, and accuracy of the retrieved absorption coefficient of the second layer obtained with the OE that was found for up to six fit parameters, with an error in the retrieved values of less than 10%. A priori information on fit parameters and fixed forward model parameters clearly improves robustness and accuracy of the inversion procedure.
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Affiliation(s)
- Fabrizio Martelli
- Università degli Studi di Firenze, Dipartimento di Fisica e Astronomia, Via G. Sansone 1, Sesto Fiorentino 50019, Firenze, Italy
| | - Samuele Del Bianco
- Istituto di Fisica Applicata Nello Carrara del Consiglio Nazionale delle Ricerche, Via Madonna del Piano 10, Sesto Fiorentino 50019, Italy
| | - Lorenzo Spinelli
- Istituto di Fotonica e Nanotecnologie, Consiglio Nazionale delle Ricerche, Piazza Leonardo da Vinci 32, Milano 20133, Italy
| | - Stefano Cavalieri
- Università degli Studi di Firenze, Dipartimento di Fisica e Astronomia, Via G. Sansone 1, Sesto Fiorentino 50019, Firenze, Italy
| | - Paola Di Ninni
- Università degli Studi di Firenze, Dipartimento di Fisica e Astronomia, Via G. Sansone 1, Sesto Fiorentino 50019, Firenze, Italy
| | - Tiziano Binzoni
- University of Geneva, Département de Neurosciences Fondamentales, 1, rue Michel-Servet 1211 Genève 4, SwitzerlandeUniversity Hospital, Département de l'Imagerie et des Sciences de l'Information Médicale, 1, 4 rue Gabrielle-Perret-Gentil, 1211 Geneva 14, S
| | - Alexander Jelzow
- Physikalisch-Technische Bundesanstalt (PTB), Abbestraße 2-12, 10587 Berlin, Germany
| | - Rainer Macdonald
- Physikalisch-Technische Bundesanstalt (PTB), Abbestraße 2-12, 10587 Berlin, Germany
| | - Heidrun Wabnitz
- Physikalisch-Technische Bundesanstalt (PTB), Abbestraße 2-12, 10587 Berlin, Germany
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Holper L, Scholkmann F, Seifritz E. Time-frequency dynamics of the sum of intra- and extracerebral hemodynamic functional connectivity during resting-state and respiratory challenges assessed by multimodal functional near-infrared spectroscopy. Neuroimage 2015; 120:481-92. [PMID: 26169319 DOI: 10.1016/j.neuroimage.2015.07.021] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Revised: 06/29/2015] [Accepted: 07/07/2015] [Indexed: 12/13/2022] Open
Abstract
Monitoring respiratory processes is important for evaluating neuroimaging data, given their influence on time-frequency dynamics of intra- and extracerebral hemodynamics. Here we investigated the time-frequency dynamics of the sum of intra- and extracerebral hemodynamic functional connectivity states during hypo- and hypercapnia by using three different respiratory challenge tasks (i.e., hyperventilation, breath-holding, and rebreathing) compared to resting-state. The sum of intra- and extracerebral hemodynamic responses were assessed using functional near-infrared spectroscopy (fNIRS) within two regions of interest (i.e., the dorsolateral and the medial prefrontal cortex). Time-frequency fNIRS analysis was performed based on wavelet transform coherence to quantify functional connectivity in terms of positive and negative phase-coupling within each region of interest. Physiological measures were assessed in the form of partial end-tidal carbon dioxide, heart rate, arterial tissue oxygen saturation, and respiration rate. We found that the three respiration challenges modulated time-frequency dynamics differently with respect to resting-state: 1) Hyperventilation and breath-holding exhibited inverse patterns of positive and negative phase-coupling. 2) In contrast, rebreathing had no significant effect. 3) Low-frequency oscillations contributed to a greater extent to time-frequency dynamics compared to high-frequency oscillations. The results highlight that there exist distinct differences in time-frequency dynamics of the sum of intra- and extracerebral functional connectivity not only between hypo- (hyperventilation) and hypercapnia but also between different states of hypercapnia (breath-holding versus rebreathing). This suggests that a multimodal assessment of intra-/extracerebral and systemic physiological changes during respiratory challenges compared to resting-state may have potential use in the differentiation between physiological and pathological respiratory behavior accompanied by the psycho-physiological state of a human.
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Affiliation(s)
- L Holper
- Department of Psychiatry, Psychotherapy, and Psychosomatics, University Hospital of Psychiatry Zurich, Lenggstrasse 31, 8032 Zurich, Switzerland.
| | - F Scholkmann
- Biomedical Optics Research Laboratory, Division of Neonatology, University Hospital Zurich, University of Zurich, Frauenklinikstrasse 10, 8091 Zurich, Switzerland
| | - E Seifritz
- Department of Psychiatry, Psychotherapy, and Psychosomatics, University Hospital of Psychiatry Zurich, Lenggstrasse 31, 8032 Zurich, Switzerland
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Time-Domain Diffuse Optical Imaging of Tissue by Non-contact Scanning. SPRINGER SERIES IN CHEMICAL PHYSICS 2015. [DOI: 10.1007/978-3-319-14929-5_18] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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Gunadi S, Leung TS, Elwell CE, Tachtsidis I. Spatial sensitivity and penetration depth of three cerebral oxygenation monitors. BIOMEDICAL OPTICS EXPRESS 2014; 5:2896-912. [PMID: 25401006 PMCID: PMC4230856 DOI: 10.1364/boe.5.002896] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 07/16/2014] [Accepted: 07/16/2014] [Indexed: 05/03/2023]
Abstract
The spatial sensitivities of NIRO-100, ISS Oximeter and TRS-20 cerebral oxygenation monitors are mapped using the local perturbation method to inform on their penetration depths and susceptibilities to superficial contaminations. The results show that TRS-20 has the deepest mean penetration depth and is less sensitive than the other monitors to a localized absorption change in the superficial layer. However, an integration time of more than five seconds is required by the TRS-20 to achieve an acceptable level of signal-to-noise ratio, which is the poorest amongst the monitors. With the exception of NIRO-100 continuous wave method, the monitors are not significantly responsive to layer-wide absorption change that occurs in the superficial layer.
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