Intraoperative multi-exposure speckle imaging of cerebral blood flow

Richards, Lisa; Kazmi, SM Shams; Olin, Katherine E.; Waldron, James S.; Fox, Douglas J.; Dunn, Andrew K.

doi:10.1177/0271678x16686987

Cited by 51 publications

(48 citation statements)

References 29 publications

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“…We reported on LSI as a real-time approach to image perfusion during laser treatment of port-wine stain birthmarks [3, [10][11][12]. Other groups reported on the use of LSI during neurosurgery [13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Momentum transfer Monte Carlo for the simulation of laser speckle imaging and its application in the skin

Regan¹,

Hayakawa²,

Choi³

2017

Biomed. Opt. Express

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Due to its simplicity and low cost, laser speckle imaging (LSI) has achieved widespread use in biomedical applications. However, interpretation of the blood-flow maps remains ambiguous, as LSI enables only limited visualization of vasculature below scattering layers such as the epidermis and skull. Here, we describe a computational model that enables flexible study of the impact of these factors on LSI measurements. The model uses Monte Carlo methods to simulate light and momentum transport in a heterogeneous tissue geometry. The virtual detectors of the model track several important characteristics of light. This model enables study of LSI aspects that may be difficult or unwieldy to address in an experimental setting, and enables detailed study of the fundamental origins of speckle contrast modulation in tissue-specific geometries. We applied the model to an in-depth exploration of the spectral dependence of speckle contrast signal in the skin, the effects of epidermal melanin content on LSI, and the depth-dependent origins of our signal. We found that LSI of transmitted light allows for a more homogeneous integration of the signal from the entire bulk of the tissue, whereas epi-illumination measurements of contrast are limited to a fraction of the light penetration depth. We quantified the spectral depth dependence of our contrast signal in the skin, and did not observe a statistically significant effect of epidermal melanin on speckle contrast. Finally, we corroborated these simulated results with experimental LSI measurements of flow beneath a thin absorbing layer. The results of this study suggest the use of LSI in the clinic to monitor perfusion in patients with different skin types, or inhomogeneous epidermal melanin distributions.

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Section: Introductionmentioning

confidence: 99%

Momentum transfer Monte Carlo for the simulation of laser speckle imaging and its application in the skin

Regan¹,

Hayakawa²,

Choi³

2017

Biomed. Opt. Express

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“…As expected, it was found that single exposure time LSCI performed relatively poorly compared to models that included multiple exposure times. The Kazmi model 12 that has been used in some studies for calculating perfusion or flow from multiexposure contrasts [20][21][22] performed better. However, it was inferior to the performance of ANN-MELSCI.…”

Section: Discussionmentioning

confidence: 99%

Machine learning in multiexposure laser speckle contrast imaging can replace conventional laser Doppler flowmetry

et al. 2019

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Laser speckle contrast imaging (LSCI) enables video rate imaging of blood flow. However, its relation to tissue blood perfusion is nonlinear and depends strongly on exposure time. By contrast, the perfusion estimate from the slower laser Doppler flowmetry (LDF) technique has a relationship to blood perfusion that is better understood. Multiexposure LSCI (MELSCI) enables a perfusion estimate closer to the actual perfusion than that using a single exposure time. We present and evaluate a method that utilizes contrasts from seven exposure times between 1 and 64 ms to calculate a perfusion estimate that resembles the perfusion estimate from LDF. The method is based on artificial neural networks (ANN) for fast and accurate processing of MELSCI contrasts to perfusion. The networks are trained using modeling of Doppler histograms and speckle contrasts from tissue models. The importance of accounting for noise is demonstrated. Results show that by using ANN, MELSCI data can be processed to LDF perfusion with high accuracy, with a correlation coefficient R ¼ 1.000 for noise-free data, R ¼ 0.993 when a moderate degree of noise is present, and R ¼ 0.995 for in vivo data from an occlusionrelease experiment. © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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“…Laser speckle imaging has become a useful tool for brain blood flow applications as the images it produces contain functional information (i.e. relative blood velocity) in addition to showing structure of the vessel networks 13,66,67 . As we previously reported, exposure time of 6 ms gave the highest SNR for imaging through WttB implant using our optical setup 24 .…”

Section: Discussionmentioning

confidence: 99%

Theranostic cranial implant for hyperspectral light delivery and microcirculation imaging without scalp removal

Davoodzadeh¹,

Cano‐Velázquez

Jonak³

et al. 2019

Preprint

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Light based techniques for imaging, diagnosing and treating the brain have become widespread clinical tools, but application of these techniques is limited by optical attenuation in the scalp and skull. This optical attenuation reduces the achievable spatial resolution, precluding the visualization of small features such as brain microvessels. The goal of this study was to assess a strategy for providing ongoing optical access to the brain without the need for repeated craniectomy or retraction of the scalp. This strategy involves the use of a transparent cranial implant and skin optical clearing agents, and was tested in mice to assess improvements in optical access which could be achieved for laser speckle imaging of cerebral microvasculature. Combined transmittance of the optically cleared scalp overlying the transparent cranial implant was as high as 89% in the NIR range, 50% in red range, 24% in green range, and 20% in blue range. In vivo laser speckle imaging experiments of mouse cerebral blood vessels showed that the proposed optical access increased signal-to-noise ratio and image resolution, allowing for visualization of microvessels through the transparent implant, which was not possible through the uncleared scalp and intact skull.

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Intraoperative multi-exposure speckle imaging of cerebral blood flow

Cited by 51 publications

References 29 publications

Momentum transfer Monte Carlo for the simulation of laser speckle imaging and its application in the skin

Momentum transfer Monte Carlo for the simulation of laser speckle imaging and its application in the skin

Machine learning in multiexposure laser speckle contrast imaging can replace conventional laser Doppler flowmetry

Theranostic cranial implant for hyperspectral light delivery and microcirculation imaging without scalp removal

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