Interferometric diffuse correlation spectroscopy improves measurements at long source–detector separation and low photon count rate

Journal of Biomedical Optics, Год журнала: 2020, Номер 25(09)

Опубликована: Сен. 30, 2020

Significance: The use of diffuse correlation spectroscopy (DCS) has shown efficacy in research studies as a technique capable noninvasively monitoring blood flow tissue with applications neuromonitoring, exercise science, and breast cancer management. ability DCS to resolve these tissues is related the optical sensitivity signal-to-noise ratio (SNR) measurements, which some cases, particularly adult cerebral inadequate significant portion population. Improvements SNR could allow for greater clinical translation this technique. Aim: Interferometric (iDCS) was characterized compared traditional homodyne determine possible benefits utilizing heterodyne detection. Approach: An iDCS system constructed by modifying fused fiber couplers create Mach–Zehnder interferometer. Comparisons between detection were performed using an intralipid phantom at two extended source–detector separations (2.4, 3.6 cm), different photon count rates, range reference arm power levels. Characterization signal mixing theory. Precision estimation diffusion coefficient autocorrelation curve measurement conditions that mimicked what would be seen vivo. Results: mixture signals present function found agree derived theory resulted accurate phantom. Improvement up ∼2 × 80% reduction variability fit observed all cases increased power. Conclusions: potential improve characterization separations, enhancing depth SNR.

Язык: Английский

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The role of diffuse correlation spectroscopy and frequency-domain near-infrared spectroscopy in monitoring cerebral hemodynamics during hypothermic circulatory arrests

JTCVS Techniques, Год журнала: 2021, Номер 7, С. 161 - 177

Опубликована: Янв. 29, 2021

Real-time noninvasive monitoring of cerebral blood flow (CBF) during surgery is key to reducing mortality rates associated with adult cardiac surgeries requiring hypothermic circulatory arrest (HCA). We explored a method monitor different brain protection techniques using diffuse correlation spectroscopy (DCS), optical technique which, combined frequency-domain near-infrared (FDNIRS), also provides measure oxygen metabolism.

Язык: Английский

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Optimization of time domain diffuse correlation spectroscopy parameters for measuring brain blood flow

Neurophotonics, Год журнала: 2021, Номер 8(03)

Опубликована: Авг. 12, 2021

Significance: Time domain diffuse correlation spectroscopy (TD-DCS) can offer increased sensitivity to cerebral hemodynamics and reduced contamination from extracerebral layers by differentiating photons based on their travel time in tissue. We have developed rigorous simulation evaluation procedures determine the optimal gate parameters for monitoring perfusion considering instrumentation characteristics realistic measurement noise. Aim: simulate TD-DCS performance different instrument response functions (IRFs) presence of experimental noise evaluate metrics brain blood flow, signal-to-noise ratio (SNR), ability reject influence flow across a variety gates operating parameters. Approach: Light propagation was modeled an MRI-derived human head geometry using Monte Carlo simulations 765- 1064-nm excitation wavelengths. use virtual probe with source–detector separation 1 cm placed pre-frontal region. Performance described above were evaluated gate(s) IRFs. Validation estimates done experiments conducted intralipid-based liquid phantom. Results: find that strongly depends system IRF. Among Gaussian pulse shapes, ∼300 ps length appears best performance, at wide (500 larger) start times 400 600 after peak TPSF 765 1064 nm, respectively, 1-s integration photon detection rates seen experimentally (600 kcps nm 4 Mcps nm). Conclusions: Our work shows satisfy competing requirements sufficient SNR. The achievable is further impacted IRF quasi-Gaussian obtained electro-optic laser shaping providing results.

Язык: Английский

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Wearable fiber-free optical sensor for continuous monitoring of neonatal cerebral blood flow and oxygenation

Pediatric Research, Год журнала: 2024, Номер 96(2), С. 486 - 493

Опубликована: Март 19, 2024

Язык: Английский

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Cerebral Blood Flow Monitoring

Oxford University Press eBooks, Год журнала: 2025, Номер unknown, С. 107 - 116

Опубликована: Май 1, 2025

Abstract Most brain-oriented therapies in neurocritical care are directed towards the maintenance of nutrient and energy supply to injured brain. Providing adequate cerebral blood flow (CBF) is a key element these strategies. Brain perfusion might also be affected other critically ill patients such as those with sepsis or during use extracorporeal mechanical haemodynamic support systems. As such, CBF monitoring often applied part multimodal brain approach determine need for, guide assess effectiveness of, brain-directed therapies. This chapter discusses techniques, which can conceptually categorized invasive non-invasive, based on imaging non-imaging methods, providing single determinations, continuous at bedside. Although many clinical decisions intended maintain restore CBF, only few CBF-guided approaches available therapy.

Язык: Английский

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Non-invasive monitoring of microcirculation dynamics in hypovolemic shock: a novel application of diffuse correlation spectroscopy

Intensive Care Medicine Experimental, Год журнала: 2025, Номер 13(1)

Опубликована: Июнь 1, 2025

Abstract Background Microcirculatory dysfunction is a poor prognostic indicator for the management of critically ill patients, highlighting need development appropriate assessment methods. Current microcirculatory parameters are often indirect, invasive, or lack immediacy and continuity, with no standardised markers critical care. Diffuse correlation spectroscopy (DCS), near-infrared optical technique, facilitates non-invasive real-time monitoring microvascular dynamics via blood flow index (BFI). However, relationship between BFI conventional in hypovolemic shock remains unclear. This study examined utility DCS assessing microcirculation during canine model. Methods Six male beagle dogs underwent controlled withdrawal to induce shock, defined as ≥ 30% decrease cardiac output (CO) mean arterial pressure (MAP) < 60 mmHg systolic (SAP) 90 mmHg. was measured using device attached skin forelimb. From baseline withdrawals followed by transfusions, changes were compared parameters, mixed venous oxygen saturation (S v O₂), core-to-skin temperature gradient (ΔT), veno-arterial difference partial carbon dioxide (PCO₂ gap), serum lactate. Correlation receiver operating characteristic (ROC) analyses performed determine cut-off value relative predicting whether lactate levels exceeded 22.5 mg/dL. Results Blood resulted significant reductions BFI, CO, radial artery flow, corresponding deteriorations ΔT, S O₂, PCO 2 gap levels. showed correlations ΔT (correlation coefficient [CC] = − 0.48, 95% confidence interval [CI] 0.69 0.18, p 0.01), SvO₂ (CC 0.67, CI 0.43 0.81, PCO2 0.63, 0.79 0.39, 0.01). ROC analysis identified threshold 35.5% elevated levels, 62% sensitivity 100% specificity (AUC 0.75). Conclusions reflects peripheral perfusion significantly correlated clinical transfusion, its potential non-invasive, continuous shock.

Язык: Английский

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Dynamic cerebral autoregulation measured by diffuse correlation spectroscopy

Journal of Cerebral Blood Flow & Metabolism, Год журнала: 2023, Номер 43(8), С. 1317 - 1327

Опубликована: Янв. 26, 2023

Dynamic cerebral autoregulation (dCA) can be derived from spontaneous oscillations in arterial blood pressure (ABP) and flow (CBF). Transcranial Doppler (TCD) measures CBF-velocity is commonly used to assess dCA. Diffuse correlation spectroscopy (DCS) a promising optical technique for non-invasive CBF monitoring, so here we aimed validate DCS as tool quantifying In 33 healthy adults 17 acute ischemic stroke patients, resting-state hemodynamic were monitored simultaneously with high-speed (20 Hz) TCD. dCA parameters calcaulated by transfer function analysis using Fourier decomposition of ABP (or CBF-velocity). Strong was found between TCD measured gain (magnitude regulation) volunteers (r = 0.73, p < 0.001) patients 0.76, 0.003). DCS-gain retained strong test-retest reliability both groups (ICC 0.87 0.82, respectively). TCD-derived phase (latency did not significantly correlate 0.12, 0.50) but moderately correlated 0.65, 0.006). DCS-derived reproducible 0.88 0.90, High-frequency bedside that leveraged quantify data, the discrepancy requires further investigation.

Язык: Английский

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Comparison of cerebral metabolic rate of oxygen, blood flow, and bispectral index under general anesthesia

Neurophotonics, Год журнала: 2023, Номер 10(01)

Опубликована: Март 6, 2023

SignificanceThe optical measurement of cerebral oxygen metabolism was evaluated.AimCompare optically derived signals to the electroencephalographic bispectral index (BIS) sensors monitor propofol-induced anesthesia during surgery.ApproachRelative metabolic rate (rCMRO2) and blood flow (rCBF) were measured by time-resolved diffuse correlation spectroscopies. Changes tested against relative BIS (rBIS) ones. The synchronism in changes also assessed R-Pearson correlation.ResultsIn 23 measurements, showed significant agreement with rBIS: propofol induction, rBIS decreased 67% [interquartile ranges (IQR) 62% 71%], rCMRO2 33% (IQR 18% 46%), rCBF 28% 10% 37%). During recovery, a increase observed for (48%, IQR 38% 55%), (29%, 17% 39%), (30%, 44%). significance direction subject-by-subject tested: coupling between rBIS, rCMRO2, witnessed majority cases (14/18 12/18 19/21 13/18 initial final part, respectively). These correlated time (R > 0.69 R = 1, p-values < 0.05).ConclusionsOptics can reliably such conditions.

Язык: Английский

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Blunt and Penetrating Severe Traumatic Brain Injury

Neurologic Clinics, Год журнала: 2021, Номер 39(2), С. 443 - 469

Опубликована: Апрель 1, 2021

Язык: Английский

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A Device-on-Chip Solution for Real-Time Diffuse Correlation Spectroscopy Using FPGA

Опубликована: Май 1, 2024

Diffuse correlation spectroscopy (DCS) is a non-invasive technology for the evaluation of blood perfusion in deep tissue. However, it requires high computational resources data analysis which poses challenges its implementation real-time applications. To address unmet need, we developed novel device-on-chip solution that fully integrates all necessary components needed DCS. It takes output photon detector and determines flow index (BFI). implemented on Field Programmable Gate Array (FPGA) chip including multi-tau correlator calculation temporal light intensity autocorrelation function DCS analyzer to perform curve fitting operation derives BFI. The FPGA system was evaluated against lab-standard both phantom cuff-ischemia studies. results indicate BFI from reference matched well. Furthermore, able achieve measurement rate 50 Hz resolve pulsatile flow.

Язык: Английский

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