Volume 28 Issue 7 | Journal of Biomedical Optics

Journal of Biomedical Optics

VOL. 28 · NO. 7 | July 2023

CONTENTS

IN THIS ISSUE

General (5)

Imaging (3)

Microscopy (2)

Sensing (1)

Errata (1)

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General

Evaluating feasibility of functional near-infrared spectroscopy in dolphins

Alexander Ruesch, Deepshikha Acharya, Eli Bulger, Jiaming Cao, Christopher McKnight, Mercy Manley, Andreas Fahlman, Barbara Shinn-Cunningham, Jana Kainerstorfer

Journal of Biomedical Optics, Vol. 28, Issue 07, 075001, (July 2023) https://doi.org/10.1117/1.JBO.28.7.075001

TOPICS: Brain, Near infrared spectroscopy, Brain tissue, Muscles, Tissues, Animals, Optical properties, Absorption, Animal model studies, Skin

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Significance

Using functional near-infrared spectroscopy (fNIRS) in bottlenose dolphins (Tursiops truncatus) could help to understand how echolocating animals perceive their environment and how they focus on specific auditory objects, such as fish, in noisy marine settings.

Aim

To test the feasibility of near-infrared spectroscopy (NIRS) in medium-sized marine mammals, such as dolphins, we modeled the light propagation with computational tools to determine the wavelengths, optode locations, and separation distances that maximize sensitivity to brain tissue.

Approach

Using frequency-domain NIRS, we measured the absorption and reduced scattering coefficient of dolphin sculp. We assigned muscle, bone, and brain optical properties from the literature and modeled light propagation in a spatially accurate and biologically relevant model of a dolphin head, using finite-element modeling. We assessed tissue sensitivities for a range of wavelengths (600 to 1700 nm), source–detector distances (50 to 120 mm), and animal sizes (juvenile model 25% smaller than adult).

Results

We found that the wavelengths most suitable for imaging the brain fell into two ranges: 700 to 900 nm and 1100 to 1150 nm. The optimal location for brain sensing positioned the center point between source and detector 30 to 50 mm caudal of the blowhole and at an angle 45 deg to 90 deg lateral off the midsagittal plane. Brain tissue sensitivity comparable to human measurements appears achievable only for smaller animals, such as juvenile bottlenose dolphins or smaller species of cetaceans, such as porpoises, or with source–detector separations ≫100 mm in adult dolphins.

Conclusions

Brain measurements in juvenile or subadult dolphins, or smaller dolphin species, may be possible using specialized fNIRS devices that support optode separations of >100 mm. We speculate that many measurement repetitions will be required to overcome hemodynamic signals originating predominantly from the muscle layer above the skull. NIRS measurements of muscle tissue are feasible today with source–detector separations of 50 mm, or even less.

Robustness of tissue oxygenation estimates by continuous wave space-resolved near infrared spectroscopy

Caterina Amendola, Davide Contini, Rebecca Re, Lorenzo Spinelli, Lorenzo Frabasile, Pietro Levoni, Alessandro Torricelli

Journal of Biomedical Optics, Vol. 28, Issue 07, 075002, (July 2023) https://doi.org/10.1117/1.JBO.28.7.075002

TOPICS: Tissues, Hemodynamics, Scattering, Near infrared spectroscopy, Oxygenation, Error analysis, Simulations, Muscles, Adaptive optics, Oxygen

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Significance

Continuous wave near infrared spectroscopy (CW-NIRS) is widely exploited in clinics to estimate skeletal muscles and brain cortex oxygenation. Spatially resolved spectroscopy (SRS) is generally implemented in commercial devices. However, SRS suffers from two main limitations: the a priori assumption on the spectral dependence of the reduced scattering coefficient [μs′(λ)] and the modeling of tissue as homogeneous.

Aim

We studied the accuracy and robustness of SRS NIRS. We investigated the errors in retrieving hemodynamic parameters, in particular tissue oxygen saturation (S_tO₂), when μs′(λ) was varied from expected values, and when layered tissue was considered.

Approach

We simulated hemodynamic variations mimicking real-life scenarios for skeletal muscles. Simulations were performed by exploiting the analytical solutions of the photon diffusion equation in different geometries: (1) semi-infinite homogeneous medium and constant μs′(λ); (2) semi-infinite homogeneous medium and linear changes in μs′(λ); (3) two-layered media with a superficial thickness s₁ = 5, 7.5, 10 mm and constant μs′(λ). All simulated data were obtained at source-detector distances ρ = 35, 40, 45 mm, and analyzed with the SRS approach to derive hemodynamic parameters (concentration of oxygenated and deoxygenated hemoglobin, total hemoglobin concentration, and tissue oxygen saturation, S_tO₂) and their relative error.

Results

Variations in μs′(λ) affect the estimated S_tO₂ (up to ±10 % ), especially if changes are different at the two wavelengths. However, the main limitation of the SRS method is the presence of a superficial layer: errors strongly larger than 20% were retrieved for the estimated S_tO₂ when the superficial thickness exceeds 5 mm.

Conclusions

These results highlight the need for more sophisticated strategies (e.g., the use of multiple short and long distances) to reduce the influence of superficial tissues in retrieving hemodynamic parameters and warn the SRS users to be aware of the intrinsic limitation of this approach, particularly when exploited in the clinical environment.

Characterization of bacteria swarming effect under plasmonic optical fiber illumination

Jang Ah Kim, Yingwei Hou, Meysam Keshavarz, Eric M. Yeatman, Alex J. Thompson

Journal of Biomedical Optics, Vol. 28, Issue 07, 075003, (July 2023) https://doi.org/10.1117/1.JBO.28.7.075003

TOPICS: Particles, Bacteria, Plasmonics, Optical fibers, Light sources and illumination, Picosecond phenomena, Convection, Laser irradiation, Windows, Ions

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Bubble dynamics and speed of jets for needle-free injections produced by thermocavitation

Nancy Elizabeth González-Sierra, José Manuel Perez-Corte, Juan Pablo Padilla-Martinez, Samuel Cruz-Vanegas, Silvio Bonfadini, Filippo Storti, Luigino Criante, Rubén Ramos-García

Journal of Biomedical Optics, Vol. 28, Issue 07, 075004, (July 2023) https://doi.org/10.1117/1.JBO.28.7.075004

TOPICS: Bubbles, Skin, Vacuum chambers, Liquids, Nozzles, Pulsed laser operation, Beam diameter, Design and modelling, Laser applications, Water

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Significance

The number of injections administered has increased dramatically worldwide due to vaccination campaigns following the COVID-19 pandemic, creating a problem of disposing of syringes and needles. Accidental needle sticks occur among medical and cleaning staff, exposing them to highly contagious diseases, such as hepatitis and human immunodeficiency virus. In addition, needle phobia may prevent adequate treatment. To overcome these problems, we propose a needle-free injector based on thermocavitation.

Aim

Experimentally study the dynamics of vapor bubbles produced by thermocavitation inside a fully buried 3D fused silica chamber and the resulting high-speed jets emerging through a small nozzle made at the top of it. The injected volume can range from ∼0.1 to 2 μL per shot. We also demonstrate that these jets have the ability to penetrate agar skin phantoms and ex-vivo porcine skin.

Approach

Through the use of a high-speed camera, the dynamics of liquid jets ejected from a microfluidic device were studied. Thermocavitation bubbles are generated by a continuous wave laser (1064 nm). The 3D chamber was fabricated by ultra-short pulse laser-assisted chemical etching. Penetration tests are conducted using agar gels (1%, 1.25%, 1.5%, 1.75%, and 2% concentrations) and porcine tissue as a model for human skin.

Result

High-speed camera video analysis showed that the average maximum bubble wall speed is about 10 to 25 m/s for almost any combination of pump laser parameters; however, a clever design of the chamber and nozzle enables one to obtain jets with an average speed of ∼70 m / s. The expelled volume per shot (0.1 to 2 μl) can be controlled by the pump laser intensity. Our injector can deliver up to 20 shots before chamber refill. Penetration of jets into agar of different concentrations and ex-vivo porcine skin is demonstrated.

Conclusions

The needle-free injectors based on thermocavitation may hold promise for commercial development, due to their cost and compactness.

Spectral correction of light emitting diodes enables accurate hydration ratio calculation using narrowband diffuse reflectance spectroscopy

Jesse Lam, Jeonghun Kim, Kelsey Tu, Dongbin Kim, Sehwan Kim

Journal of Biomedical Optics, Vol. 28, Issue 07, 075005, (July 2023) https://doi.org/10.1117/1.JBO.28.7.075005

TOPICS: Light emitting diodes, Photodiodes, Tissues, Emulsions, Chromophores, Reflectivity, Simulations, Diffuse reflectance spectroscopy, Spectroscopy, Crosstalk

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Imaging

Mapping estimates of vascular permeability with a clinical indocyanine green fluorescence imaging system in experimental pancreatic adenocarcinoma tumors

Matthew Reed, Marien Ochoa, Kenneth Tichauer, Ashley Weichmann, Marvin Doyley, Brian Pogue

Journal of Biomedical Optics, Vol. 28, Issue 07, 076001, (July 2023) https://doi.org/10.1117/1.JBO.28.7.076001

TOPICS: Tumors, Tissues, Imaging systems, Permeability, Capillaries, Fluorescence imaging, Muscles, Data modeling, Biological imaging, Skin

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Assessing the effects of prenatal poly-drug exposure on fetal brain vasculature using optical coherence angiography

Raksha Raghunathan, Jessica Gutierrez, Chih-Hao Liu, Manmohan Singh, Rajesh C. Miranda, Kirill V. Larin

Journal of Biomedical Optics, Vol. 28, Issue 07, 076002, (July 2023) https://doi.org/10.1117/1.JBO.28.7.076002

TOPICS: Bioalcohols, Fetus, Brain, Optical coherence tomography, Angiography, 3D image processing, Optical coherence, Neuroimaging, Photoacoustic imaging, Animals

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Cortical microvascular blood flow velocity mapping by combining dynamic light scattering optical coherence tomography and two-photon microscopy

Qi Pian, Mohammed Alfadhel, Jianbo Tang, Grace V. Lee, Baoqiang Li, Buyin Fu, Yagmur Ayata, Mohammad Abbas Yaseen, David A. Boas, Timothy W. Secomb, Sava Sakadzic

Journal of Biomedical Optics, Vol. 28, Issue 07, 076003, (July 2023) https://doi.org/10.1117/1.JBO.28.7.076003

TOPICS: Angiography, Optical coherence tomography, Capillaries, Blood circulation, Image segmentation, Brain, Biological imaging, Data acquisition, Voxels, Velocity measurements

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Significance

The accurate large-scale mapping of cerebral microvascular blood flow velocity is crucial for a better understanding of cerebral blood flow (CBF) regulation. Although optical imaging techniques enable both high-resolution microvascular angiography and fast absolute CBF velocity measurements in the mouse cortex, they usually require different imaging techniques with independent system configurations to maximize their performances. Consequently, it is still a challenge to accurately combine functional and morphological measurements to co-register CBF speed distribution from hundreds of microvessels with high-resolution microvascular angiograms.

Aim

We propose a data acquisition and processing framework to co-register a large set of microvascular blood flow velocity measurements from dynamic light scattering optical coherence tomography (DLS-OCT) with the corresponding microvascular angiogram obtained using two-photon microscopy (2PM).

Approach

We used DLS-OCT to first rapidly acquire a large set of microvascular velocities through a sealed cranial window in mice and then to acquire high-resolution microvascular angiograms using 2PM. The acquired data were processed in three steps: (i) 2PM angiogram coregistration with the DLS-OCT angiogram, (ii) 2PM angiogram segmentation and graphing, and (iii) mapping of the CBF velocities to the graph representation of the 2PM angiogram.

Results

We implemented the developed framework on the three datasets acquired from the mice cortices to facilitate the coregistration of the large sets of DLS-OCT flow velocity measurements with 2PM angiograms. We retrieved the distributions of red blood cell velocities in arterioles, venules, and capillaries as a function of the branching order from precapillary arterioles and postcapillary venules from more than 1000 microvascular segments.

Conclusions

The proposed framework may serve as a useful tool for quantitative analysis of large microvascular datasets obtained by OCT and 2PM in studies involving normal brain functioning, progression of various diseases, and numerical modeling of the oxygen advection and diffusion in the realistic microvascular networks.

Microscopy

Investigating ionizing radiation-induced changes in breast cancer cells using stimulated Raman scattering microscopy

Christian Harry Allen, Robyn Skillings, Duale Ahmed, Sarita Cuadros Sanchez, Kaitlyn Altwasser, George Hilan, William Willmore, Vinita Chauhan, Edana Cassol, Sangeeta Murugkar

Journal of Biomedical Optics, Vol. 28, Issue 07, 076501, (July 2023) https://doi.org/10.1117/1.JBO.28.7.076501

TOPICS: Cancer, Proteins, Breast cancer, Raman spectroscopy, Ion irradiation, Ionizing radiation, Radiotherapy, Raman scattering, Iron, Tissues

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Expanding the applicability of multiphoton fluorescence recovery after photobleaching by incorporating shear stress in laminar flow

Tresa M. Elias, Edward B. Brown Jr., Edward B. Brown III

Journal of Biomedical Optics, Vol. 28, Issue 07, 076502, (July 2023) https://doi.org/10.1117/1.JBO.28.7.076502

TOPICS: Diffusion, Fluorescence, Systems modeling, Multiphoton fluorescence microscopy, Molecules, Data modeling, Simulations, Photobleaching, Microfluidics, Mathematical modeling

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Sensing

Dual-ratio approach for detection of point fluorophores in biological tissue

Giles Blaney, Fernando Ivich, Angelo Sassaroli, Mark Niedre, Sergio Fantini

Journal of Biomedical Optics, Vol. 28, Issue 07, 077001, (July 2023) https://doi.org/10.1117/1.JBO.28.7.077001

TOPICS: Signal to noise ratio, Fluorophores, Fluorescence, Tissues, Signal detection, Target detection, Near infrared, Interference (communication), In vivo imaging, Skin

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Errata

Influence of edge enhancement applied in endoscopic systems on sharpness and noise (Erratum)

Geert Geleijnse, Bernd Rieger

Journal of Biomedical Optics, Vol. 28, Issue 07, 079801, (July 2023) https://doi.org/10.1117/1.JBO.28.7.079801

TOPICS: Endoscopy, Imaging systems, Throat, Physics, Nose, Image sharpness, Ear, Biomedical optics, Applied sciences

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