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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Diffuse correlation spectroscopy: current status and future outlook

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

Опубликована: Янв. 24, 2023

Diffuse correlation spectroscopy (DCS) has emerged as a versatile, noninvasive method for deep tissue perfusion assessment using near-infrared light. A broad class of applications is being pursued in neuromonitoring and beyond. However, technical limitations the technology originally implemented remain barriers to wider adoption. wide variety approaches improve measurement performance reduce cost are explored; these include interferometric methods, camera-based multispeckle detection, long path photon selection improved depth sensitivity. We review here current status DCS summarize future development directions challenges that on widespread

Язык: Английский

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Complete head cerebral sensitivity mapping for diffuse correlation spectroscopy using subject-specific magnetic resonance imaging models

Biomedical Optics Express, Год журнала: 2022, Номер 13(3), С. 1131 - 1131

Опубликована: Янв. 21, 2022

We characterize cerebral sensitivity across the entire adult human head for diffuse correlation spectroscopy, an optical technique increasingly used bedside perfusion monitoring. Sixteen subject-specific magnetic resonance imaging-derived models were to identify high regions by running Monte Carlo light propagation simulations at over eight hundred uniformly distributed locations on head. Significant spatial variations in sensitivity, consistent subjects, found. also identified correlates of such differences suitable real-time assessment. These can be largely attributed changes extracerebral thickness and should taken into account optimize probe placement experimental settings.

Язык: Английский

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Improved accuracy of cerebral blood flow quantification in the presence of systemic physiology cross-talk using multi-layer Monte Carlo modeling

Neurophotonics, Год журнала: 2021, Номер 8(01)

Опубликована: Янв. 1, 2021

Significance: Contamination of diffuse correlation spectroscopy (DCS) measurements cerebral blood flow (CBF) due to systemic physiology remains a significant challenge in the clinical translation DCS for neuromonitoring. Tunable, multi-layer Monte Carlo-based (MC) light transport models have potential remove extracerebral cross-talk index ( CBFi ) estimates. Aim: We explore effectiveness MC recovering accurate changes presence strong variations during hypercapnia maneuver. Approach: Multi-layer slab and head-like realistic (curved) geometries were used run simulations photon propagation through head. The simulation data post-processed into with variable thicknesses fit multi-distance intensity autocorrelation estimate timecourses. results values from set human subject sessions compared estimated using semi-infinite analytical model, as commonly field. Results: Group averages indicate gradual increase following different temporal profile versus expected rapid CBF response. Optimized models, guided by several intrinsic criteria pressure modulation maneuver, able more effectively separate scalp influence than fitting, which assumed homogeneous medium. Three-layer performed better two-layer ones; curved achieved largely similar results, though closer physiological layer thicknesses. Conclusion: Three-layer, adjustable can be useful separating distinct brain flow. Pressure modulation, along reasonable estimates parameters, help direct choice appropriate models.

Язык: Английский

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Optical monitoring of cerebral perfusion and metabolism in adults during cardiac surgery with cardiopulmonary bypass

Biomedical Optics Express, Год журнала: 2020, Номер 11(10), С. 5967 - 5967

Опубликована: Сен. 3, 2020

During cardiac surgery with cardiopulmonary bypass (CPB), adequate maintenance of cerebral blood flow (CBF) is vital in preventing postoperative neurological injury - i.e. stroke, delirium, cognitive impairment. Reductions CBF large enough to impact energy metabolism can lead tissue damage and subsequent brain injury. Current methods for neuromonitoring during are limited. This study presents the clinical translation a hybrid optical neuromonitor continuous intraoperative monitoring perfusion ten patients undergoing non-emergent non-pulsatile CPB. The system combines broadband near-infrared spectroscopy (B-NIRS) measure changes oxidation state cytochrome c oxidase (oxCCO) direct marker cellular diffuse correlation (DCS) provide an index (CBFi). As heart was arrested CPB-pump started, increases CBFi (88.5 ± 125.7%) significant decreases oxCCO (-0.5 0.2 µM) were observed; no noted transitions off Fifteen hypoperfusion events, defined as sustained reductions rate, identified across all resulted when mean arterial pressure dropped 30 mmHg or below. maximum reduction preceded corresponding metabolic by 18.2 15.0 s. Optical provides safe non-invasive approach assessing has potential guiding patient management prevent adverse outcomes.

Язык: Английский

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The Potential Role of fNIRS in Evaluating Levels of Consciousness

Frontiers in Human Neuroscience, Год журнала: 2021, Номер 15

Опубликована: Июль 8, 2021

Over the last few decades, neuroimaging techniques have transformed our understanding of brain and effect neurological conditions on function. More recently, light-based modalities such as functional near-infrared spectroscopy gained popularity tools to study function at bedside. A recent application is assess residual awareness in patients with disorders consciousness, some retain albeit lacking all behavioural response commands. Functional can play a vital role identifying these by assessing command-driven activity. The goal this review summarise studies reported topic, discuss technical ethical challenges working outline promising future directions field.

Язык: Английский

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Assessment of a Non-Invasive Brain Pulse Monitor to Measure Intra-Cranial Pressure Following Acute Brain Injury

Medical Devices Evidence and Research, Год журнала: 2023, Номер Volume 16, С. 15 - 26

Опубликована: Янв. 1, 2023

Background: Intracranial pressure (ICP) monitoring requires placing a hole in the skull through which an invasive monitor is inserted into brain. This approach has risks for patient and expensive. We have developed non-invasive brain pulse that uses red light to detect photoplethysmographic (PPG) signal arising from blood vessels on brain's cortical surface. The PPG ICP waveform share morphological features may allow measurement of intracranial pressure. Methods: enrolled critically ill patients with acute injury assess new monitor. A total 24 simultaneous measurements were undertaken 12 over range levels. Results: morphologies similar approach. Both methods demonstrated progressive increase amplitude P2 relative P1 increasing An automated algorithm was relation level. correlation between morphology levels, R 2 =0.66, P < 0.001. Conclusion: monitor's these provide method measure Trial Registration: ACTRN12620000828921. Keywords: pressure, injury, monitoring, non-invasive, photoplethysmography

Язык: Английский

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Assessing changes in regional cerebral hemodynamics in adults with a high-density full-head coverage time-resolved near-infrared spectroscopy device

Journal of Biomedical Optics, Год журнала: 2024, Номер 29(S3)

Опубликована: Май 3, 2024

Cerebral oximeters have the potential to detect abnormal cerebral blood oxygenation allow for early intervention. However, current commercial systems two major limitations: (1) spatial coverage of only frontal region, assuming that surgery-related hemodynamic effects are global and (2) susceptibility extracerebral signal contamination inherent continuous-wave near-infrared spectroscopy (NIRS).

Язык: Английский

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A comprehensive overview of diffuse correlation spectroscopy: theoretical framework, recent advances in hardware, analysis, and applications

NeuroImage, Год журнала: 2024, Номер 298, С. 120793 - 120793

Опубликована: Авг. 15, 2024

Diffuse correlation spectroscopy (DCS) is a powerful tool for assessing microvascular hemodynamic in deep tissues. Recent advances sensors, lasers, and learning have further boosted the development of new DCS methods. However, newcomers might feel overwhelmed, not only by already-complex theoretical framework but also broad range component options system architectures. To facilitate entry to this exciting field, we present comprehensive review hardware architectures (continuous-wave, frequency-domain, time-domain) summarize corresponding models. Further, discuss applications highly integrated silicon single-photon avalanche diode (SPAD) sensors DCS, compare SPADs with existing other components (lasers, correlators), as well data analysis tools, including learning. Potential medical diagnosis are discussed an outlook future directions provided, offer effective guidance embark on research.

Язык: Английский

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Relationship Between Signals from Cerebral near Infrared Spectroscopy Sensor Technology and Objectively Measured Cerebral Blood Volume: A Systematic Scoping Review

Sensors, Год журнала: 2025, Номер 25(3), С. 908 - 908

Опубликована: Фев. 3, 2025

Cerebral blood volume (CBV) is an essential metric that indicates and evaluates various healthy pathologic conditions. Most methods of CBV measurement are cumbersome have a poor temporal resolution. Recently, it has been proposed signals derived metrics from cerebral near-infrared spectroscopy (NIRS), non-invasive sensor, can be used to estimate CBV. However, this association remains vastly unexplored. As such, scoping review aimed examine the literature on relationship between NIRS A search six databases was conducted conforming Preferred Reporting Items for Systematic Reviews Meta-Analyses guidelines assess following question: What associations CBV? The database yielded 3350 unique results. Seven these articles were included in based inclusion exclusion criteria. An additional study identified while examining articles’ reference sections. Overall, systematic shows extreme variation CBV, with few sources objectively documenting true statistical two. This highlights current critical knowledge gap emphasizes need further research area.

Язык: Английский

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