In vivo time-domain diffuse correlation spectroscopy above the water absorption peak

Colombo, Lorenzo; Pagliazzi, Marco; Sekar, Sanathana Konugolu Venkata; Contini, Davide; Durdurán, Turgut; Pifferi, Antonio

doi:10.1364/ol.392355

Cited by 23 publications

(10 citation statements)

References 21 publications

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“…Through the use of the dual stage amplification and custom laser shaping, together with SNSPD detection, we were able to fully realize the promise of long-wavelength (1,064 nm) operation (in comparison, the system reported by Colombo et al (2020) was limited to shorter wavelengths near 1,000 nm where the attenuation is significantly higher than at 1,064 nm and used an InGaAs photomultiplier tube with 2% quantum efficiency). The increased SNR allows for the measurement of clear arterial pulsation at an acquisition rate of > 5 Hz at the late gate and 1.5 cm separation in all subjects.…”

Section: Discussionmentioning

confidence: 99%

“…Previously reported TD-DCS systems ( Pagliazzi et al, 2017 ; Tamborini et al, 2019 ; Colombo et al, 2020 ; Samaei et al, 2021b ) face limitations with respect to detector efficiency and/or the characteristics of the IRF. To address these limitations, and building on our previous work demonstrating the benefits of DCS measurements at 1,064 nm ( Carp et al, 2020 ; Ozana et al, 2021 ), as well as simulation studies by our group ( Mazumder et al, 2021 ) and others ( Qiu et al, 2018 , 2021 ; Colombo et al, 2019 ) indicating the importance of optimizing laser source characteristics for TD-DCS, we developed a high-performance, next-generation TD-DCS system employing a custom 1,064 nm laser source and superconducting nanowire single photon detectors (SNSPDs, overall size of 69 × 49.5 × 113 cm for depth, width, and height, respectively) to maximize measurement performance and enable functional brain imaging.…”

Section: Introductionmentioning

confidence: 99%

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Functional Time Domain Diffuse Correlation Spectroscopy

et al. 2022

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Time-domain diffuse correlation spectroscopy (TD-DCS) offers a novel approach to high-spatial resolution functional brain imaging based on the direct quantification of cerebral blood flow (CBF) changes in response to neural activity. However, the signal-to-noise ratio (SNR) offered by previous TD-DCS instruments remains a challenge to achieving the high temporal resolution needed to resolve perfusion changes during functional measurements. Here we present a next-generation optimized functional TD-DCS system that combines a custom 1,064 nm pulse-shaped, quasi transform-limited, amplified laser source with a high-resolution time-tagging system and superconducting nanowire single-photon detectors (SNSPDs). System characterization and optimization was conducted on homogenous and two-layer intralipid phantoms before performing functional CBF measurements in six human subjects. By acquiring CBF signals at over 5 Hz for a late gate start time of the temporal point spread function (TPSF) at 15 mm source-detector separation, we demonstrate for the first time the measurement of blood flow responses to breath-holding and functional tasks using TD-DCS.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Functional Time Domain Diffuse Correlation Spectroscopy

et al. 2022

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“…We focused on obtaining good quality of data for this first patient of our clinical study with the traditional NIR wavelength of~785 nm. In the future, these detectors can be used at longer wavelengths (e.g., 1064 nm), which is expected to increase the signal~10-fold, based on the previous work [39,40].…”

Section: Discussionmentioning

confidence: 99%

Noninvasive Optical Monitoring of Cerebral Blood Flow and EEG Spectral Responses after Severe Traumatic Brain Injury: A Case Report

et al. 2021

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Survivors of severe brain injury may require care in a neurointensive care unit (neuro-ICU), where the brain is vulnerable to secondary brain injury. Thus, there is a need for noninvasive, bedside, continuous cerebral blood flow monitoring approaches in the neuro-ICU. Our goal is to address this need through combined measurements of EEG and functional optical spectroscopy (EEG-Optical) instrumentation and analysis to provide a complementary fusion of data about brain activity and function. We utilized the diffuse correlation spectroscopy method for assessing cerebral blood flow at the neuro-ICU in a patient with traumatic brain injury. The present case demonstrates the feasibility of continuous recording of noninvasive cerebral blood flow transients that correlated well with the gold-standard invasive measurements and with the frequency content changes in the EEG data.

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“…Our experimental setup, for details see Ref. [9], is based on a custom Ti:Sapphire modelocked laser, tuned to a pulse width of 200 ps full-width at half-maximum. The laser light was injected in the tissue with a 100 µm core diameter graded-index fiber and the diffused light was recollected, at a SD separation ρ = 1 cm in reflectance, with a 4.4 µm core diameter single-mode fiber (780HP, Thorlabs, Germany).…”

Section: Introduction and Methodsmentioning

confidence: 99%

In vivo time-domain diffuse correlation spectroscopy at 1 μm

Colombo

Pagliazzi

Sekar

et al. 2021

Optical Tomography and Spectroscopy of Tissue XIV

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Diffuse correlation spectroscopy (DCS) is an optical technique which, by studying the speckle intensity fluctuations of coherent light diffused in a turbid medium, retrieves information regarding the scatterers motion. In the case of biological tissues, the particles of interest are the red blood cells, from which is possible to measure non-invasively microvascular blood flow (BF). However, being based on a continuous-wave light source, depth discrimination is achievable only by using multiple source-detector separations. On the other hand, time-domain (TD) DCS is a novel approach which exploits a pulsed yet coherent light source to discriminate the intensity fluctuations at different photon time-of-flights. This additional information is beneficial for in vivo applications, due to the physical relationship between photon time-of-flight and mean depth penetration. TD-DCS is typically performed in the spectral range between 700 and 800 nm. Here, we explore TD-DCS in a new spectral range compared to the typical one, moving to the spectral region beyond the water absorption peak (i.e., >970 nm). We performed liquid phantom and in vivo experiments on the human muscle at a wavelength of 1000 nm. Also, the possible advantages in terms of depth sensitivity and signal-to-noise ratio are discussed.

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In vivo time-domain diffuse correlation spectroscopy above the water absorption peak

Cited by 23 publications

References 21 publications

Functional Time Domain Diffuse Correlation Spectroscopy

Functional Time Domain Diffuse Correlation Spectroscopy

Noninvasive Optical Monitoring of Cerebral Blood Flow and EEG Spectral Responses after Severe Traumatic Brain Injury: A Case Report

In vivo time-domain diffuse correlation spectroscopy at 1 μm

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