Clinical applications of near-infrared diffuse correlation spectroscopy and tomography for tissue blood flow monitoring and imaging

Physiological Measurement, Год журнала: 2017, Номер 38(4), С. R1 - R26

Опубликована: Фев. 15, 2017

Blood flow is one such available observable promoting a wealth of physiological insight both individually and in combination with other metrics.Near-infrared diffuse correlation spectroscopy (DCS) and, to lesser extent, tomography (DCT), have increasingly received interest over the past decade as noninvasive methods for tissue blood measurements imaging. DCS/DCT offers several attractive features measurements/imaging noninvasiveness, portability, high temporal resolution, relatively large penetration depth (up centimeters).This review first introduces basic principle instrumentation DCS/DCT, followed by presenting clinical application examples diagnosis therapeutic monitoring diseases variety organs/tissues including brain, skeletal muscle, tumor.Clinical study results demonstrate technical versatility providing important information disease intervention monitoring.

Язык: Английский

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Highly parallel, interferometric diffusing wave spectroscopy for monitoring cerebral blood flow dynamics

Optica, Год журнала: 2018, Номер 5(5), С. 518 - 518

Опубликована: Апрель 26, 2018

Light-scattering methods are widely used in soft matter physics and biomedical optics to probe dynamics turbid media, such as diffusion colloids or blood flow biological tissue.These typically rely on fluctuations of coherent light intensity, therefore cannot accommodate more than a few modes per detector.This limitation has hindered efforts measure deep tissue with high speed, since weak diffuse fluxes, together low singlemode fiber throughput, result photon count rates.To solve this, we introduce multimode (MMF) interferometry the field optics.In doing so, transform standard complementary metal-oxide-semiconductor (CMOS) camera into sensitive detector array for fluxes that tissue.Specifically, build novel CMOS-based, interferometric diffusing wave spectroscopy (iDWS) system show it can ∼20 speckles simultaneously near shot noise limit, acting essentially independent photon-counting channels.We develop matrix formalism, based MMF mode solutions geometry, predict both coherence speckle number iDWS.After validation liquid phantoms, demonstrate iDWS pulsatile measurements at 2.5 cm source-detector separation adult human brain vivo.By achieving highly parallel CMOS camera, this work promises enhance performance reduce cost optical instruments.

Язык: Английский

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Direct assessment of extracerebral signal contamination on optical measurements of cerebral blood flow, oxygenation, and metabolism

Neurophotonics, Год журнала: 2020, Номер 7(04)

Опубликована: Окт. 7, 2020

Significance: Near-infrared spectroscopy (NIRS) combined with diffuse correlation (DCS) provides a noninvasive approach for monitoring cerebral blood flow (CBF), oxygenation, and oxygen metabolism. However, these methods are vulnerable to signal contamination from the scalp. Our work evaluated of reducing impact this using time-resolved (TR) NIRS multidistance (MD) DCS. Aim: The magnitude scalp was by measuring flow, metabolic responses global hemodynamic challenge. Contamination assessed collecting data without impeding flow. Approach: Experiments involved healthy participants. A pneumatic tourniquet used cause ischemia, as confirmed contrast-enhanced NIRS, computerized gas system generate hypercapnic Results: Comparing acquired demonstrated that TR-NIRS technique could reduce contributions in signals up 4 times (rSD = 3 cm) 6 cm). Similarly, brain be separated analyzing MD DCS multilayer model. Using techniques, there no change metabolism during hypercapnia, expected, despite large increases CBF oxygenation. Conclusion: NIRS/DCS can accurately monitor appropriate enhancement depth sensitivity, highlighting potential techniques neuromonitoring.

Язык: Английский

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Prolonged monitoring of cerebral blood flow and autoregulation with diffuse correlation spectroscopy in neurocritical care patients

Neurophotonics, Год журнала: 2018, Номер 5(04), С. 1 - 1

Опубликована: Ноя. 13, 2018

Monitoring of cerebral blood flow (CBF) and autoregulation are essential components neurocritical care, but continuous noninvasive methods for CBF monitoring lacking. Diffuse correlation spectroscopy (DCS) is a diffuse optical modality that measures index (CBF_i) in the cortex microvasculature by rapid fluctuations near-infrared light diffusing through moving red cells. We tested feasibility CBF_i with DCS at-risk patients Neurosciences Intensive Care Unit. data were acquired continuously up to 20 h six aneurysmal subarachnoid hemorrhage, as permitted clinical care. Mean arterial pressure was recorded synchronously, allowing us derive curves compute an index. The suggest disrupted most patients, severity disruption limits preserved varying between subjects. Our findings potential noninvasive, long-term perfusion, autoregulation.

Язык: Английский

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Fast and sensitive diffuse correlation spectroscopy with highly parallelized single photon detection

APL Photonics, Год журнала: 2021, Номер 6(2)

Опубликована: Фев. 1, 2021

Diffuse correlation spectroscopy (DCS) is a well-established method that measures rapid changes in scattered coherent light to identify blood flow and functional dynamics within tissue. While its sensitivity minute scatterer displacements leads number of unique advantages, conventional DCS systems become photon-limited when attempting probe deep into the tissue, which long measurement windows (∽1 sec). Here, we present high-sensitivity system with 1024 parallel detection channels integrated single-photon avalanche diode array demonstrate ability detect mm-scale perturbations up 1 cm tissue-like phantom at 33 Hz sampling rate. We also show this highly parallelized strategy can measure human pulse high fidelity behaviorally induced physiological variations from above prefrontal cortex. By greatly improving speed, opens new experiments for high-speed biological signal measurement.

Язык: Английский

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Functional interferometric diffusing wave spectroscopy of the human brain

Science Advances, Год журнала: 2021, Номер 7(20)

Опубликована: Май 12, 2021

Cerebral blood flow (CBF) is essential for brain function, and CBF-related signals can inform us about activity. Yet currently, high-end medical instrumentation needed to perform a CBF measurement in adult humans. Here, we describe functional interferometric diffusing wave spectroscopy (fiDWS), which introduces collects near-infrared light via the scalp, using inexpensive detector arrays rapidly monitor coherent fluctuations that encode index (BFI), surrogate CBF. Compared other optical approaches, fiDWS measures BFI faster deeper while also providing continuous absorption signals. Achieving clear pulsatile waveforms at source-collector separations of 3.5 cm, confirm BFI, not absorption, shows graded hypercapnic response consistent with human cerebrovascular physiology, has better contrast-to-noise ratio than during activation. By high-throughput measurements low cost, will expand access

Язык: Английский

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A portable optical pulsatile flowmetry demonstrates strong clinical relevance for diabetic foot perfusion assessment

APL Bioengineering, Год журнала: 2024, Номер 8(1)

Опубликована: Фев. 21, 2024

We present a robust, cost-effective (<2000 USD), and portable optical diffuse speckle pulsatile flowmetry (DSPF) device with flexible handheld probe for deep tissue blood flow measurement in the human foot as well first-in-man observational clinical study using proposed ischemia assessment peripheral artery disease (PAD) diagnosis. Blood is inherently nature. However, most conventional methods cannot measure tissue-level noninvasively. The can ∼6 mm underneath skin surface. A new quantitative perfusion index (TPIDSPF) based on frequency domain analysis of waveform defined to assess status. Through involving 66 subjects, including healthy individuals diabetes patients without PAD, TPIDSPF demonstrated strong correlations 0.720 transcutaneous partial oxygen pressure (TcPO2) 0.652 toe–brachial (TBI). Moreover, among three methods, highest area under curve PAD diagnosis patients, notable value 0.941. promising results suggest that method has potential be an effective tool identifying diabetic cohort.

Язык: Английский

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Effects of exercise training on calf muscle oxygen extraction and blood flow in patients with peripheral artery disease

Journal of Applied Physiology, Год журнала: 2017, Номер 123(6), С. 1599 - 1609

Опубликована: Окт. 5, 2017

We employed near-infrared optical techniques, diffuse correlation spectroscopy (DCS), and frequency-domain (FD-NIRS) to test the hypothesis that supervised exercise training increases skeletal muscle microvascular blood flow oxygen extraction in patients with peripheral artery disease (PAD) who experience claudication. PAD ( n = 64) were randomly assigned control groups. Patients group received 3 mo of training. Calf optically monitored before, during, after performance a graded treadmill protocol at baseline both Additionally, measurements ankle-brachial index (ABI) peak walking time (PWT) maximal claudication made during each patient visit. Supervised was found increase calf levels by 29% (13%, 50%) 8% (1%, 12%), respectively [ P < 0.001; median (25th percentile, 75th percentile)]. These improvements across population significantly higher than corresponding changes 0.004). Exercise also increased PWT 49% (18%, 101%) 0.01). However, within statistical error, ABI, resting extraction, recovery half-time for hemoglobin\myoglobin desaturation following cessation not altered The concurrent monitoring hybrid DCS/FD-NIRS instrument revealed enhanced oxidative metabolism physical activity from training, which could be an underlying mechanism observed improvement PWT. NEW & NOTEWORTHY report on noninvasive dynamics before/during/after tracked effects 3-mo improved ability activity.

Язык: Английский

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Noninvasive optical monitoring of critical closing pressure and arteriole compliance in human subjects

Journal of Cerebral Blood Flow & Metabolism, Год журнала: 2017, Номер 37(8), С. 2691 - 2705

Опубликована: Май 25, 2017

The critical closing pressure ( CrCP) of the cerebral circulation depends on both tissue intracranial and vasomotor tone. CrCP defines arterial blood ABP) at which flow approaches zero, their difference ABP - is an accurate estimate perfusion pressure. Here we demonstrate a novel non-invasive technique for continuous monitoring bedside. methodology combines optical diffuse correlation spectroscopy (DCS) measurements pulsatile in arterioles with concurrent data during cardiac cycle. Together, two waveforms permit calculation via two-compartment Windkessel model arterioles. Measurements by optics transcranial Doppler ultrasound (TCD) were carried out 18 healthy adults; they demonstrated good agreement (R = 0.66, slope 1.14 ± 0.23) means 11.1 5.0 13.0 7.5 mmHg, respectively. Additionally, potentially useful rarely measured arteriole compliance parameter was derived from phase between DCS waveforms. provide evidence that signals originate predominantly are well suited long-term assessment clinic.

Язык: Английский

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Noninvasive continuous optical monitoring of absolute cerebral blood flow in critically ill adults

Neurophotonics, Год журнала: 2018, Номер 5(04), С. 1 - 1

Опубликована: Ноя. 23, 2018

We investigate a scheme for noninvasive continuous monitoring of absolute cerebral blood flow (CBF) in adult human patients based on combination time-resolved dynamic contrast-enhanced near-infrared spectroscopy (DCE-NIRS) and diffuse correlation (DCS) with semi-infinite head model photon propogation. Continuous CBF is obtained via calibration the DCS index (BFI) by intermittent intravenous injections optical contrast agent indocyanine green. A coefficient (γ) thus determined, permitting conversion BFI to units at all other times. study acute brain injury (N = 7) carried out ascertain stability γ. The patient-averaged across multiple days was good agreement between two coefficients measured different times during single found. 1.24 × 109 ( mL / 100 g min ) cm2 s applied previously from similar brain-injured patients; this case, underestimated compared XeCT, an effect we show primarily due use homogeneous models head.

Язык: Английский

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