Open-source FlexNIRS: A low-cost, wireless and wearable cerebral health tracker

Wu, Kuan-Cheng; Tamborini, Davide; Renna, Marco; Peruch, Adriano; Huang, Yujing; Martin, Alyssa; Kaya, Kutlu; Starkweather, Zachary; Zavriyev, Alexander I.; Carp, Stefan A.; Salat, David H.; Franceschini, Maria Angela

doi:10.1016/j.neuroimage.2022.119216

Cited by 12 publications

(11 citation statements)

References 41 publications

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“…A new open‐source device (FlexNIRS) has been described recently with a reported cost as low as $50/unit. The authors have emphasized their revolutionary low cost, ease‐of‐use, smart‐phone readiness, accuracy, real‐time data quality feedback, and long battery life suitable for low resource settings, especially for medically underserved communities and telehealth applications 54 . Future research directions include the provision of sleep staging to provide a more accurate assessment of SDB‐related hemodynamic changes and to identify postoperative changes related to adenotonsillectomy to understand the causal implications of our observations.…”

Section: Discussionmentioning

confidence: 99%

Resting‐State Cerebral Hemodynamics is Associated With Problem Behaviors in Pediatric Sleep‐Disordered Breathing

Isaiah

Teplitzky

Dontu

et al. 2023

Otolaryngol.--head neck surg.

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ObjectiveUntreated sleep‐disordered breathing (SDB) is associated with problem behaviors in children. The neurological basis for this relationship is unknown. We used functional near‐infrared spectroscopy (fNIRS) to assess the relationship between cerebral hemodynamics of the frontal lobe of the brain and problem behaviors in children with SDB.Study DesignCross‐sectional.SettingUrban tertiary care academic children's hospital and affiliated sleep center.MethodsWe enrolled children with SDB aged 5 to 16 years old referred for polysomnography. We measured fNIRS‐derived cerebral hemodynamics within the frontal lobe during polysomnography. We assessed parent‐reported problem behaviors using the Behavioral Response Inventory of Executive Function Second Edition (BRIEF‐2). We compared the relationships between (i) the instability in cerebral perfusion in the frontal lobe measured fNIRS, (ii) SDB severity using apnea‐hypopnea index (AHI), and (iii) BRIEF‐2 clinical scales using Pearson correlation (r). A p < .05 was considered significant.ResultsA total of 54 children were included. The average age was 7.8 (95% confidence interval, 7.0‐8.7) years; 26 (48%) were boys and 25 (46%) were Black. The mean AHI was 9.9 (5.7‐14.1). There is a statistically significant inverse relationship between the coefficient of variation of perfusion in the frontal lobe and BRIEF‐2 clinical scales (range of r = 0.24‐0.49, range of p = .076 to <.001). The correlations between AHI and BRIEF‐2 scales were not statistically significant.ConclusionThese results provide preliminary evidence for fNIRS as a child‐friendly biomarker for the assessment of adverse outcomes of SDB.

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Section: Discussionmentioning

confidence: 99%

Resting‐State Cerebral Hemodynamics is Associated With Problem Behaviors in Pediatric Sleep‐Disordered Breathing

Isaiah

Teplitzky

Dontu

et al. 2023

Otolaryngol.--head neck surg.

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“…To quantify slow changes in SO2 and hemoglobin concentration, we used a mixed approach based on the multi-distance self-calibrating method described in Ref. 22 to calculate initial values and a single-distance modified Beer–Lambert law method to calculate hemoglobin changes. After ambient light subtraction, followed by a 1-s moving averaging, light intensity attenuation at 2.8 and 3.3 cm was used to recover absorption coefficients (μa), assuming reduced scattering coefficients (μs′) of 6.8 cm−1 at 735 nm and 5.9 cm−1 at 850 nm 22 , 38 .…”

Section: Methodsmentioning

confidence: 99%

“…22 to calculate initial values and a single-distance modified Beer–Lambert law method to calculate hemoglobin changes. After ambient light subtraction, followed by a 1-s moving averaging, light intensity attenuation at 2.8 and 3.3 cm was used to recover absorption coefficients (μa), assuming reduced scattering coefficients (μs′) of 6.8 cm−1 at 735 nm and 5.9 cm−1 at 850 nm 22 , 38 . A 75% water fraction was used to estimate hemoglobin concentration and oxygenation 39 .…”

Section: Methodsmentioning

confidence: 99%

“…Because NIRS measurements at the same sampling rate typically detect multiple orders of magnitude more photons, the SNR of NIRS is much better than the SNR of DCS, 19 , 20 allowing for the measurement of pulsatile blood volume waveforms with high temporal resolution at long SDsep (≥3 cm) 21 . In particular, we recently developed an open-source, wearable, and wireless NIRS device, called FlexNIRS, with a low noise equivalent power (NEP<70 fW/√Hz), able to acquire 10 channels at up to 266 Hz sampling rate 22 . The high SNR performance of this device allows us to resolve the pulsatile blood volume and its time derivative to perform cerebral pulse waveform analysis (PWA) on the pulsatile light absorbance of NIRS photoplethysmography (PPG) at a 3.3 cm SDsep (NIRS-PPG) with zero to a few beats averaging.…”

Section: Introductionmentioning

confidence: 99%

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Enhancing diffuse correlation spectroscopy pulsatile cerebral blood flow signal with near-infrared spectroscopy photoplethysmography

Wu,

Martin,

Renna

et al. 2023

Neurophoton.

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Combining near-infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS) allows for quantifying cerebral blood volume, flow, and oxygenation changes continuously and non-invasively. As recently shown, the DCS pulsatile cerebral blood flow index (pCBF i ) can be used to quantify critical closing pressure (CrCP) and cerebrovascular resistance (CVR i ).Aim: Although current DCS technology allows for reliable monitoring of the slow hemodynamic changes, resolving pulsatile blood flow at large source-detector separations, which is needed to ensure cerebral sensitivity, is challenging because of its low signal-to-noise ratio (SNR). Cardiac-gated averaging of several arterial pulse cycles is required to obtain a meaningful waveform.Approach: Taking advantage of the high SNR of NIRS, we demonstrate a method that uses the NIRS photoplethysmography (NIRS-PPG) pulsatile signal to model DCS pCBF i , reducing the coefficient of variation of the recovered pulsatile waveform (pCBF i-fit ) and allowing for an unprecedented temporal resolution (266 Hz) at a large source-detector separation (>3 cm).Results: In 10 healthy subjects, we verified the quality of the NIRS-PPG pCBF i-fit during common tasks, showing high fidelity against pCBF i (R 2 0.98 AE 0.01). We recovered CrCP and CVR i at 0.25 Hz, >10 times faster than previously achieved with DCS.Conclusions: NIRS-PPG improves DCS pCBF i SNR, reducing the number of gate-averaged heartbeats required to recover CrCP and CVR i .

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“…Different techniques, algorithms, and devices have been explored to estimate StO2. [1][2][3] Main approaches are broadband near-infrared spectroscopy, spatially resolved spectroscopy (SRS), and time or frequency-domain measurements. SRS offers the potential to extend continuous wave (CW) systems for fNIRS with a small number of NIR wavelengths towards oximetry.…”

Section: Introductionmentioning

confidence: 99%

Accuracy of tissue oxygen saturation measurement with multidistance CW fNIRS: a phantom study

Motamed Jahromi,

Yang,

Grosenick

et al. 2023

Diffuse Optical Spectroscopy and Imaging IX

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We investigate the potential of CW fNIRS with two NIR wavelengths to estimate tissue oxygen saturation by a model based on spatially resolved spectroscopy. Phantoms with optical properties similar to brain tissue are applied to study the influence of the optical parameters and the spatial probe configuration on effective attenuation, absorption, and oxygen saturation. Attenuation coefficients and saturation values can be estimated with a typical discrepancy of 5%, whereas absorption coefficients show larger deviations from the true values. The results are very sensitive against small errors in the source-detector separation.

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Open-source FlexNIRS: A low-cost, wireless and wearable cerebral health tracker

Cited by 12 publications

References 41 publications

Resting‐State Cerebral Hemodynamics is Associated With Problem Behaviors in Pediatric Sleep‐Disordered Breathing

Resting‐State Cerebral Hemodynamics is Associated With Problem Behaviors in Pediatric Sleep‐Disordered Breathing

Enhancing diffuse correlation spectroscopy pulsatile cerebral blood flow signal with near-infrared spectroscopy photoplethysmography

Accuracy of tissue oxygen saturation measurement with multidistance CW fNIRS: a phantom study

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