Cerebral blood flow and autoregulation: current measurement techniques and prospects for noninvasive optical methods

Neurophotonics, Год журнала: 2016, Номер 3(3), С. 031411 - 031411

Опубликована: Июнь 21, 2016

Cerebral blood flow (CBF) and cerebral autoregulation (CA) are critically important to maintain proper brain perfusion supply the with necessary oxygen energy substrates. Adequate is required support normal function, achieve successful aging, navigate acute chronic medical conditions. We review general principles of CBF measurements current techniques measure based on direct intravascular measurements, nuclear medicine, X-ray imaging, magnetic resonance ultrasound techniques, thermal diffusion, optical methods. also for arterial pressure as well theoretical experimental methods assessment CA, including recent approaches techniques. The in clinical practice presented. comprehensive description principles, methods, requirements CA highlights potentially role that noninvasive can play neurovascular health. In fact, have ability provide a noninvasive, quantitative, continuous monitor autoregulation.

Язык: Английский

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Modified Beer-Lambert law for blood flow

Biomedical Optics Express, Год журнала: 2014, Номер 5(11), С. 4053 - 4053

Опубликована: Окт. 28, 2014

We develop and validate a Modified Beer-Lambert law for blood flow based on diffuse correlation spectroscopy (DCS) measurements.The new formulation enables monitoring from temporal intensity autocorrelation function data taken at single or multiple delay-times.Consequentially, the speed of optical measurement can be substantially increased.The scheme facilitates highly scattering tissues in geometries wherein light propagation is diffusive non-diffusive, it particularly well-suited utilization with pressure paradigms that employ differential signals to reduce contributions superficial tissues.

Язык: Английский

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Optical imaging and spectroscopy for the study of the human brain: status report

Neurophotonics, Год журнала: 2022, Номер 9(S2)

Опубликована: Авг. 30, 2022

This report is the second part of a comprehensive two-part series aimed at reviewing an extensive and diverse toolkit novel methods to explore brain health function. While first focused on neurophotonic tools mostly applicable animal studies, here, we highlight optical spectroscopy imaging relevant noninvasive human studies. We outline current state-of-the-art technologies software advances, most recent impact these neuroscience clinical applications, identify areas where innovation needed, provide outlook for future directions.

Язык: Английский

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Fast blood flow monitoring in deep tissues with real-time software correlators

Biomedical Optics Express, Год журнала: 2016, Номер 7(3), С. 776 - 776

Опубликована: Фев. 3, 2016

We introduce, validate and demonstrate a new software correlator for high-speed measurement of blood flow in deep tissues based on diffuse correlation spectroscopy (DCS).The scheme employs standard PC-based data acquisition boards to measure temporal intensity autocorrelation functions continuously at 50 -100 Hz, the fastest measurements reported with DCS date.The streams, obtained vivo typical source-detector separations 2.5 cm, easily resolve pulsatile heart-beat fluctuations which were previously considered be noise.We employ device separate tissue from absorption/scattering dynamics thereby show that origin signal is primarily flow, we monitor cerebral autoregulation healthy volunteers more accurately than traditional instrumentation as result increased rates.Finally, characterize signal-to-noise ratio identify count rate averaging parameters needed optimal performance.

Язык: Английский

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Simultaneous functional near-infrared spectroscopy and electroencephalography for monitoring of human brain activity and oxygenation: a review

Neurophotonics, Год журнала: 2017, Номер 4(04), С. 1 - 1

Опубликована: Авг. 22, 2017

Multimodal monitoring has become particularly common in the study of human brain function. In this context, combined, synchronous measurements functional near-infrared spectroscopy (fNIRS) and electroencephalography (EEG) are getting increased interest. Because absence electro-optical interference, it is quite simple to integrate these two noninvasive recording procedures activity. fNIRS EEG both scalp-located procedures. estimates hemodynamic fluctuations relying on spectroscopic measurements, whereas captures macroscopic temporal dynamics electrical activity through passive voltages evaluations. The "orthogonal" neurophysiological information provided by technologies increasing interest neurovascular coupling phenomenon further encourage their integration. This review provides, together with an introduction regarding principles future directions technologies, evaluation major clinical nonclinical applications flexible, low-cost combination neuroimaging modalities. fNIRS–EEG systems exploit ability be conducted environment or experimental setting and/or subjects that generally not suited for other modalities, such as magnetic resonance imaging, positron emission tomography, magnetoencephalography. settles itself a useful multimodal tool investigation.

Язык: Английский

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Continuous non-invasive optical monitoring of cerebral blood flow and oxidative metabolism after acute brain injury

Journal of Cerebral Blood Flow & Metabolism, Год журнала: 2019, Номер 39(8), С. 1469 - 1485

Опубликована: Май 14, 2019

Rapid detection of ischemic conditions at the bedside can improve treatment acute brain injury. In this observational study 11 critically ill brain-injured adults, we employed a monitoring approach that interleaves time-resolved near-infrared spectroscopy (TR-NIRS) measurements cerebral oxygen saturation and extraction fraction (OEF) with diffuse correlation (DCS) measurement blood flow (CBF). Using approach, demonstrate clinical promise non-invasive, continuous optical changes in CBF metabolic rate (CMRO 2 ). addition, CMRO measures were compared to invasive tissue tension (PbtO ), thermal diffusion flowmetry CBF, microdialysis obtained concurrently. The information successfully distinguished between ischemic, hypermetabolic, hyperemic arose spontaneously during patient care. Moreover, pressor-induced mean arterial pressure enabled assessment autoregulation. total, findings suggest hybrid non-invasive neurometabolic monitor (NNOM) facilitate adverse physiological injured patients are otherwise difficult measure conventional techniques.

Язык: Английский

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Neonatal NIRS monitoring: recommendations for data capture and review of analytics

Journal of Perinatology, Год журнала: 2021, Номер 41(4), С. 675 - 688

Опубликована: Фев. 15, 2021

Язык: Английский

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Combined multi-distance frequency domain and diffuse correlation spectroscopy system with simultaneous data acquisition and real-time analysis

Biomedical Optics Express, Год журнала: 2017, Номер 8(9), С. 3993 - 3993

Опубликована: Авг. 7, 2017

Frequency domain near infrared spectroscopy (FD-NIRS) and diffuse correlation (DCS) have emerged as synergistic techniques for the non-invasive assessment of tissue health. Combining FD-NIRS oximetry with DCS measures blood flow, oxygen metabolic rate can be quantified, a parameter more closely linked to underlying physiology pathology than either NIRS or estimates alone. Here we describe first commercially available integrated instrument, called "MetaOx", designed enable simultaneous measurements at rates 10 + Hz, offering real-time data evaluation. We show simultaneously acquired characterization demonstrating performance equivalent individual devices sample in vivo pulsation resolved forearm occlusion hemodynamic changes muscle monitoring during stationary bike exercise.

Язык: Английский

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Pressure modulation algorithm to separate cerebral hemodynamic signals from extracerebral artifacts

Neurophotonics, Год журнала: 2015, Номер 2(3), С. 035004 - 035004

Опубликована: Авг. 4, 2015

We introduce and validate a pressure measurement paradigm that reduces extracerebral contamination from superficial tissues in optical monitoring of cerebral blood flow with diffuse correlation spectroscopy (DCS). The scheme determines subject-specific contributions to the DCS signal by utilizing probe modulation induce variations flow. For analysis, head is modeled as two-layer medium probed long short source-detector separations. Then combination modified Beer-Lambert law for enables experimenters linearly relate differential signals variation without priori anatomical information. demonstrate algorithm's ability isolate during finger-tapping task graded scalp ischemia healthy adults. Finally, we adapt algorithm ameliorate oxygenation volume near-infrared spectroscopy.

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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