3,684 results match your criteria Biomed Opt Express[Journal]


Spectroscopic properties of various blood antigens/antibodies.

Biomed Opt Express 2020 Apr 1;11(4):2298-2312. Epub 2020 Apr 1.

CinnaGen Medical Biotechnology Research Center, Alborz University of Medical Sciences, P.O.Box 3165933155, Alborz, Iran.

Since the traditional method generates biological waste, there is a significant demand for an easy, quick technique of blood type identification without contamination. In fact, individuals can be divided into four main blood groups whose antigens are available in red blood cell (RBC) membranes and the antibodies in the plasma. Here, UV-vis and photoluminescence (PL) spectroscopic methods are systematically used to find the spectra of blood typing antigens (A, B and AB) and antibodies i. Read More

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http://dx.doi.org/10.1364/BOE.387112DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173882PMC

Measuring cell displacements in opaque tissues: dynamic light scattering in the multiple scattering regime.

Biomed Opt Express 2020 Apr 31;11(4):2277-2297. Epub 2020 Mar 31.

Université Grenoble Alpes, Laboratoire Interdisciplinaire de Physique, CNRS, F-38000 Grenoble, France.

Coherent light scattered by tissues brings structural and dynamic information, at depth, that standard imaging techniques cannot reach. Dynamics of cells or sub-cellular elements can be measured thanks to dynamic light scattering in thin samples (single scattering regime) or thanks to diffusive wave spectroscopy in thick samples (diffusion regime). Here, we address the intermediate regime and provide an analytical relationship between scattered light fluctuations and the distribution of cell displacements as a function of time. Read More

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http://dx.doi.org/10.1364/BOE.388360DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173902PMC

Visualization of blood cell contrast in nailfold capillaries with high-speed reverse lens mobile phone microscopy.

Biomed Opt Express 2020 Apr 30;11(4):2268-2276. Epub 2020 Mar 30.

Department of Biomedical Engineering, Johns Hopkins University (JHU), 3400 N. Charles Street, Baltimore, MD 21218, USA.

Quantification of optical absorption gaps in nailfold capillaries has recently shown promise as a non-invasive technique for neutropenia screening. Here we demonstrate a low-cost, portable attachment to a mobile phone that can resolve optical absorption gaps in nailfold capillaries using a reverse lens technique and oblique 520nm illumination. Resolution <4m within a 1mm on-axis region is demonstrated, and wide field of view (3. Read More

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http://dx.doi.org/10.1364/BOE.382376DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173903PMC

Terahertz three-dimensional monitoring of nanoparticle-assisted laser tissue soldering.

Biomed Opt Express 2020 Apr 27;11(4):2254-2267. Epub 2020 Mar 27.

Institut National de la Recherche Scientifique (INRS), Centre Énergie, Matériaux et Télécommunications (EMT), Varennes, QC J3X 1S2, Canada.

In view of minimally-invasive clinical interventions, laser tissue soldering assisted by plasmonic nanoparticles is emerging as an appealing concept in surgical medicine, holding the promise of surgeries without sutures. Rigorous monitoring of the plasmonically-heated solder and the underlying tissue is crucial for optimizing the soldering bonding strength and minimizing the photothermal damage. To this end, we propose a non-invasive, non-contact, and non-ionizing modality for monitoring nanoparticle-assisted laser-tissue interaction and visualizing the localized photothermal damage, by taking advantage of the unique sensitivity of terahertz radiation to the hydration level of biological tissue. Read More

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http://dx.doi.org/10.1364/BOE.389561DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173899PMC

High resolution 3D visualization of the spinal cord in a post-mortem murine model.

Biomed Opt Express 2020 Apr 27;11(4):2235-2253. Epub 2020 Mar 27.

Institute of Nanotechnology- CNR, Rome Unit, Piazzale Aldo Moro 5, Italy.

A crucial issue in the development of therapies to treat pathologies of the central nervous system is represented by the availability of non-invasive methods to study the three-dimensional morphology of spinal cord, with a resolution able to characterize its complex vascular and neuronal organization. X-ray phase contrast micro-tomography enables a high-quality, 3D visualization of both the vascular and neuronal network simultaneously without the need of contrast agents, destructive sample preparations or sectioning. Until now, high resolution investigations of the post-mortem spinal cord in murine models have mostly been performed in spinal cords removed from the spinal canal. Read More

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http://dx.doi.org/10.1364/BOE.386837DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173906PMC

Thermal damage threshold of neurons during infrared stimulation.

Biomed Opt Express 2020 Apr 27;11(4):2224-2234. Epub 2020 Mar 27.

Faculty of Science, Engineering and Technology, Swinburne University of Technology, John Street, Hawthorn, VIC 3122, Australia.

In infrared neural stimulation (INS), laser-evoked thermal transients are used to generate small depolarising currents in neurons. The laser exposure poses a moderate risk of thermal damage to the target neuron. Indeed, exogenous methods of neural stimulation often place the target neurons under stressful non-physiological conditions, which can hinder ordinary neuronal function and hasten cell death. Read More

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http://dx.doi.org/10.1364/BOE.383165DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173919PMC

Label-free imaging flow cytometer for analyzing large cell populations by line-field quantitative phase microscopy with digital refocusing.

Biomed Opt Express 2020 Apr 26;11(4):2213-2223. Epub 2020 Mar 26.

Central Research Laboratory, Hamamatsu Photonics K.K., 5000 Hirakuchi, Hamakita-ku, Hamamatsu, Shizuoka-Pref., 434-8601, Japan.

We propose a line-field quantitative phase-imaging flow cytometer for analyzing large populations of label-free cells. Hydrodynamical focusing brings cells into the focus plane of an optical system while diluting the cell suspension, resulting in decreased throughput rate. To overcome the trade-off between throughput rate and in-focus imaging, our cytometer involves digitally extending the depth-of-focus on loosely hydrodynamically focusing cell suspensions. Read More

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http://dx.doi.org/10.1364/BOE.389435DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173910PMC

Realization of a time-correlated photon counting technique for fluorescence analysis.

Biomed Opt Express 2020 Apr 25;11(4):2205-2212. Epub 2020 Mar 25.

Beijing Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Beijing Normal University, Beijing 100875, China.

An ultralow level light detection module, the time-correlated photon counter, is proposed and evaluated for fluorescence analysis. The time-correlated photon counter employs a silicon photomultiplier as a photon counting sensor in conjunction with a Poisson statistics algorithm and a double time windows technique, and therefore it can accurately count the photon number. The time-correlated photon counter is compatible with the time-correlated single photon counting technique and can record the arrival time of very faint light signals. Read More

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http://dx.doi.org/10.1364/BOE.385870DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173894PMC
April 2020
3.648 Impact Factor

Spectral clustering-based resting-state network detection approach for functional near-infrared spectroscopy.

Biomed Opt Express 2020 Apr 24;11(4):2191-2204. Epub 2020 Mar 24.

The Department of Psychology, Renmin University of China, Beijing, China.

In recent years, studying the resting-state network (RSN) by using functional near-infrared spectroscopy (fNIRS) has received increased attention. The previous resting-state fNIRS studies mainly adopted the seed-based correlation and the independent component analysis to detect RSN. However, these methods have several inherent problems. Read More

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http://dx.doi.org/10.1364/BOE.387919DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173901PMC

Thermographic detection and quantification of THC in oral fluid at unprecedented low concentrations.

Biomed Opt Express 2020 Apr 24;11(4):2178-2190. Epub 2020 Mar 24.

Department of Mechanical Engineering, Lassonde School of Engineering, York University, 4700 Keele St., Toronto, ON, M3J 1P3, Canada.

With recent changes in the legalization of cannabis around the world, there is an urgent need for rapid, yet sensitive, screening devices for testing drivers and employees under the influence of cannabis at the roadside and at the workplace, respectively. Oral fluid lateral flow immunoassays (LFAs) have recently been explored for such applications. While LFAs offer on-site, low-cost and rapid detection of tetrahydrocannabinol (THC), their nominal detection threshold is about 25 ng/ml, which is well above the 1-5 ng/ml limits set by regulations. Read More

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http://dx.doi.org/10.1364/BOE.388990DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173880PMC

Development and clinical trial of a smartphone-based colorimetric detection system for self-monitoring of blood glucose.

Biomed Opt Express 2020 Apr 23;11(4):2166-2177. Epub 2020 Mar 23.

iXensor Co., Ltd, Taiwan.

Blood glucose measurements help to guide insulin therapy, thus reducing disease severities, secondary complications, and related mortalities. Efforts are underway to allow diabetes patients to experience a more convenient way to measure blood glucose and consequently increase their adherence to regular self-monitoring of blood glucose (SMBG). This study demonstrated a new SMBG system that integrated all components of a glucometer via a smartphone's optical sensing module to detect the colorimetric blood strip and obtains the blood glucose concentration with calculations performed by an application install in the smartphone. Read More

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http://dx.doi.org/10.1364/BOE.389638DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173904PMC

Tomographic imaging with an ultrasound and LED-based photoacoustic system.

Biomed Opt Express 2020 Apr 23;11(4):2152-2165. Epub 2020 Mar 23.

Biomedical Photonic Imaging Group, Technical Medical Center, University of Twente, The Netherlands.

Pulsed lasers in photoacoustic tomography systems are expensive, which limit their use to a few clinics and small animal labs. We present a method to realize tomographic ultrasound and photoacoustic imaging using a commercial LED-based photoacoustic and ultrasound system. We present two illumination configurations using LED array units and an optimal number of angular views for tomographic reconstruction. Read More

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http://dx.doi.org/10.1364/BOE.384548DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173893PMC
April 2020
3.648 Impact Factor

Functional optical coherence tomography and photoacoustic microscopy imaging for zebrafish larvae.

Biomed Opt Express 2020 Apr 23;11(4):2137-2151. Epub 2020 Mar 23.

Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.

We present a dual modality functional optical coherence tomography and photoacoustic microscopy (OCT-PAM) system. The photoacoustic modality employs an akinetic optical sensor with a large imaging window. This imaging window enables direct reflection mode operation, and a seamless integration of optical coherence tomography (OCT) as a second imaging modality. Read More

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http://dx.doi.org/10.1364/BOE.390410DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173920PMC

Automatic protocol for quantifying the vasoconstriction in blood vessel images.

Biomed Opt Express 2020 Apr 20;11(4):2122-2136. Epub 2020 Mar 20.

MOE Key Laboratory of OptoElectronic Science and Technology for Medicine, Fujian Provincial Key Laboratory for Photonics Technology, Fujian Normal University, Fuzhou, 350117, China.

Vascular targeted photodynamic therapy (V-PDT) has been successfully utilized for various vascular-related diseases. To optimize the PDT dose and treatment protocols for clinical treatments and to elucidate the biological mechanisms for V-PDT, blood vessels in the dorsal skin-fold window chamber (DSWC) of nude mice are often chosen to perform studies. In this study, a new automatic protocol to quantify the vasoconstriction of blood vessels in the DSWC model is proposed, which focused on tracking the pixels of blood vessels in pre- V-PDT images that disappear after V-PDT. Read More

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http://dx.doi.org/10.1364/BOE.387080DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173888PMC

Polarization contrast optical diffraction tomography.

Biomed Opt Express 2020 Apr 20;11(4):2109-2121. Epub 2020 Mar 20.

Department of Imaging Physics, Lorentzweg 1, 2628 CJ, Delft, The Netherlands.

We demonstrate large scale polarization contrast optical diffraction tomography (ODT). In cross-polarized sample arm detection configuration we determine, from the amplitude of the optical wavefield, a relative measure of the birefringence projection. In parallel-polarized sample arm detection configuration we image the conventional phase projection. Read More

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http://dx.doi.org/10.1364/BOE.381992DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173917PMC

Concepts for structured illumination microscopy with extended axial resolution through mirrored illumination.

Biomed Opt Express 2020 Apr 20;11(4):2098-2108. Epub 2020 Mar 20.

Department of Chemical Engineering & Biotechnology, University of Cambridge, CB3 0AS, UK.

Wide-field fluorescence microscopy, while much faster than confocal microscopy, suffers from a lack of optical sectioning and poor axial resolution. 3D structured illumination microscopy (SIM) has been demonstrated to provide optical sectioning and to double the resolution limit both laterally and axially, but even with this the axial resolution is still worse than the lateral resolution of unmodified wide-field microscopy. Interferometric schemes using two high numerical aperture objectives, such as 4Pi confocal and IM microscopy, have improved the axial resolution beyond that of the lateral, but at the cost of a significantly more complex optical setup. Read More

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http://dx.doi.org/10.1364/BOE.382398DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173891PMC

Three-dimensional visualization of opacifications in the murine crystalline lens by in vivo optical coherence tomography.

Biomed Opt Express 2020 Apr 19;11(4):2085-2097. Epub 2020 Mar 19.

Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Austria.

Diagnostic classification techniques used to diagnose cataracts, the world's leading cause of blindness, are currently based on subjective methods. Here, we present optical coherence tomography as a noninvasive tool for volumetric visualization of lesions formed in the crystalline lens. A custom-made swept-source optical coherence tomography (SS-OCT) system was utilized to investigate the murine crystalline lens. Read More

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http://dx.doi.org/10.1364/BOE.387335DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173898PMC

Corneal hydration assessment indicator based on terahertz time domain spectroscopy.

Biomed Opt Express 2020 Apr 18;11(4):2073-2084. Epub 2020 Mar 18.

Tianjin Eye Hospital, Tianjin Key Laboratory of Ophthalmology and Visual Science, Tianjin Eye Institute, Tianjin 300020, China.

Terahertz technology has shown broad prospects for measuring corneal water content, which is an important parameter of ocular health. Based on terahertz time-domain spectroscopy, a new indicator named characteristic ratio (CR) of the sum of low (0.2-0. Read More

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http://dx.doi.org/10.1364/BOE.387826DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173912PMC

Wide-field optical spectroscopy system integrating reflectance and spatial frequency domain imaging to measure attenuation-corrected intrinsic tissue fluorescence in radical prostatectomy specimens.

Biomed Opt Express 2020 Apr 17;11(4):2052-2072. Epub 2020 Mar 17.

Polytechnique Montreal, Dept. of Engineering Physics, C.P. 6079, Succ. Centre-ville, Montreal, QC H3C 3A7, Canada.

The development of a multimodal optical imaging system is presented that integrates endogenous fluorescence and diffuse reflectance spectroscopy with single-wavelength spatial frequency domain imaging (SFDI) and surface profilometry. The system images specimens at visible wavelengths with a spatial resolution of 70 µm, a field of view of 25 cm and a depth of field of ∼1.5 cm. Read More

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http://dx.doi.org/10.1364/BOE.388482DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173915PMC

Multimodal quantitative optical elastography of the crystalline lens with optical coherence elastography and Brillouin microscopy.

Biomed Opt Express 2020 Apr 17;11(4):2041-2051. Epub 2020 Mar 17.

Department of Biomedical Engineering, University of Houston, Houston, TX 77030, USA.

Assessing the biomechanical properties of the crystalline lens can provide crucial information for diagnosing disease and guiding precision therapeutic interventions. Existing noninvasive methods have been limited to global measurements. Here, we demonstrate the quantitative assessment of the elasticity of crystalline lens with a multimodal optical elastography technique, which combines dynamic wave-based optical coherence elastography (OCE) and Brillouin microscopy to overcome the drawbacks of individual modalities. Read More

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http://dx.doi.org/10.1364/BOE.387361DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173892PMC

Label-free optical imaging in developmental biology [Invited].

Biomed Opt Express 2020 Apr 13;11(4):2017-2040. Epub 2020 Mar 13.

Department of Molecular Physiology and Biophysics, Baylor College of Medicine, 1 Baylor Plaza, Houston, TX 77030, USA.

Application of optical imaging in developmental biology marks an exciting frontier in biomedical optics. Optical resolution and imaging depth allow for investigation of growing embryos at subcellular, cellular, and whole organism levels, while the complexity and variety of embryonic processes set multiple challenges stimulating the development of various live dynamic embryonic imaging approaches. Among other optical methods, label-free optical techniques attract an increasing interest as they allow investigation of developmental mechanisms without application of exogenous markers or fluorescent reporters. Read More

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http://dx.doi.org/10.1364/BOE.381359DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173889PMC

Multifunctional laser speckle imaging.

Biomed Opt Express 2020 Apr 13;11(4):2007-2016. Epub 2020 Mar 13.

Optical Bioimaging Laboratory, Department of Biomedical Engineering, National University of Singapore, 7 Engineering Drive 1, Singapore 117574, Singapore.

We have developed a multi-functional laser speckle imaging system, which can be operated in both the surface illumination laser speckle contrast imaging (SI-LSCI) mode and the line scan laser speckle contrast imaging (LS-LSCI) mode. The system has been applied to imaging the chicken embryos to visualize both the blood flow and morphological details of the vasculature. The experimental results demonstrated that LS-LSCI is capable of detecting and quantifying blood flow in blood vessels smaller and deeper than those detectable by conventional SI-LSCI. Read More

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http://dx.doi.org/10.1364/BOE.388856DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173886PMC

Hyperspectral evaluation of peritoneal fibrosis in mouse models.

Biomed Opt Express 2020 Apr 13;11(4):1991-2006. Epub 2020 Mar 13.

Faculty of Mathematics and Physics, University of Ljubljana, Jadranska ulica 19, 1000 Ljubljana, Slovenia.

Analysis of morphological changes of the peritoneal membrane is an essential part of animal studies when investigating molecular mechanisms involved in the development of peritoneal fibrosis or testing the effects of potential therapeutic agents. Current methods, such as histology and immunohistochemistry, require time consuming sample processing and analysis and result in limited spatial information. In this paper we present a new method to evaluate structural and chemical changes in an animal model of peritoneal fibrosis that is based on hyperspectral imaging and a model of light transport. Read More

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http://dx.doi.org/10.1364/BOE.387837DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173895PMC

Discriminating different grades of cervical intraepithelial neoplasia based on label-free phasor fluorescence lifetime imaging microscopy.

Biomed Opt Express 2020 Apr 13;11(4):1977-1990. Epub 2020 Mar 13.

Department of Optical Science and Engineering, Shanghai Engineering Research Center of Ultra-precision Optical Manufacturing, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Green Photoelectron Platform, Fudan University, 220 Handan Road, Shanghai 200433, China.

This study proposed label-free fluorescence lifetime imaging and phasor analysis methods to discriminate different grades of cervical intraepithelial neoplasia (CIN). The human cervical tissue lesions associated with cellular metabolic abnormalities were detected by the status changes of important coenzymes in cells and tissues, reduced nicotinamide adenine dinucleotide (phosphate) (NAD(P)H) and flavin adenine dinucleotide (FAD). Fluorescence lifetime imaging microscopy (FLIM) was used to study human cervical tissues, human cervical epithelial cells, and standard samples. Read More

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http://dx.doi.org/10.1364/BOE.386999DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173885PMC

Metasurface-based total internal reflection microscopy.

Biomed Opt Express 2020 Apr 13;11(4):1967-1976. Epub 2020 Mar 13.

Ctr. de Nanosciences et de Nanotechnologies, Univ. Paris-Sud, Univ. Paris-Saclay, France.

Recent years have seen a tremendous progress in the development of dielectric metasurfaces for visible light applications. Such metasurfaces are ultra-thin optical devices that can manipulate optical wavefronts in an arbitrary manner. Here, we present a newly developed metasurface which allows for coupling light into a microscopy coverslip to achieve total internal reflection (TIR) excitation. Read More

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http://dx.doi.org/10.1364/BOE.385276DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173909PMC

Forward multiple scattering dominates speckle decorrelation in whole-blood flowmetry using optical coherence tomography.

Biomed Opt Express 2020 Apr 13;11(4):1947-1966. Epub 2020 Mar 13.

Wellman Center for Photomedicine, Harvard Medical School and Massachusetts General Hospital, 40 Blossom Street, Boston, Massachusetts 02114, USA.

Quantitative blood flow measurements using optical coherence tomography (OCT) have a wide potential range of medical research and clinical applications. Flowmetry based on the temporal dynamics of the OCT signal may have the ability to measure three-dimensional flow profiles regardless of the flow direction. State-of-the-art models describing the OCT signal temporal statistics are based on dynamic light scattering (DLS), a model which is inherently limited to single scattering regimes. Read More

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http://dx.doi.org/10.1364/BOE.384539DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173878PMC

Platform for quantitative multiscale imaging of tissue composition.

Biomed Opt Express 2020 Apr 12;11(4):1927-1946. Epub 2020 Mar 12.

Morgridge Institute for Research, 330 N Orchard St, Madison, WI 53715, USA.

Changes in the multi-level physical structure of biological features going from cellular to tissue level composition is a key factor in many major diseases. However, we are only beginning to understand the role of these structural changes because there are few dedicated multiscale imaging platforms with sensitivity at both the cellular and macrostructural spatial scale. A single platform reduces bias and complications from multiple sample preparation methods and can ease image registration. Read More

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http://dx.doi.org/10.1364/BOE.383248DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173879PMC

Optical diffraction tomography with finite object support for the minimization of missing cone artifacts.

Authors:
Wojciech Krauze

Biomed Opt Express 2020 Apr 11;11(4):1919-1926. Epub 2020 Mar 11.

Warsaw University of Technology, Institute of Micromechanics and Photonics, Św. A. Boboli 8 Street, 02-525 Warsaw, Poland.

Limited-angle optical diffraction tomography suffers from strong artifacts in tomographic reconstructions. Numerous algorithms, mainly based on regularization methods, have been developed recently to overcome this limitation. However, the quality of results still needs further improvement. Read More

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http://dx.doi.org/10.1364/BOE.386507DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173890PMC

Determination of refractive index, size, and solid content of monodisperse polystyrene microsphere suspensions for the characterization of optical phantoms.

Biomed Opt Express 2020 Apr 11;11(4):1901-1918. Epub 2020 Mar 11.

University of Ljubljana, Faculty of Electrical Engineering, Laboratory of Imaging Technologies, Tržaška cesta 25, SI-1000, Ljubljana, Slovenia.

Monodisperse polystyrene microspheres are often utilized in optical phantoms since optical properties such as the scattering coefficient and the scattering phase function can be calculated using the Mie theory. However, the calculated values depend on the inherent physical parameters of the microspheres which include the size, refractive index, and solid content. These parameters are often provided only approximately or can be affected by long shelf times. Read More

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http://dx.doi.org/10.1364/BOE.387619DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173914PMC

Peripheral image quality in pseudophakic eyes.

Biomed Opt Express 2020 Apr 11;11(4):1892-1900. Epub 2020 Mar 11.

Department of Research, Athens Eye Hospital, Leof. Vouliagmenis 45, Glifada 166 75, Greece.

The purpose of this work was to evaluate peripheral image quality in the pseudophakic eye using computational, physical, and psychophysical methods. We designed and constructed a physical model of the pseudophakic human eye with realistic dimensions using a corneal phantom and a board-only camera that was pivoted around an axis that matched the anatomical center of a human retina, assuming a radius of curvature of 12 mm, while it was submersed in a 23.4 mm long water filled chamber to emulate human ocular axial length. Read More

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http://dx.doi.org/10.1364/BOE.387254DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173905PMC

Detail-preserving pulse wave extraction from facial videos using consumer-level camera.

Biomed Opt Express 2020 Apr 11;11(4):1876-1891. Epub 2020 Mar 11.

School of Computer and Information, Hefei University of Technology, Hefei, 230009, China.

With the popularity of smart phones, non-contact video-based vital sign monitoring using a camera has gained increased attention over recent years. Especially, imaging photoplethysmography (IPPG), a technique for extracting pulse waves from videos, conduces to monitor physiological information on a daily basis, including heart rate, respiration rate, blood oxygen saturation, and so on. The main challenge for accurate pulse wave extraction from facial videos is that the facial color intensity change due to cardiovascular activities is subtle and is often badly disturbed by noise, such as illumination variation, facial expression changes, and head movements. Read More

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http://dx.doi.org/10.1364/BOE.380646DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173900PMC

Frugal filtering optical lenses for point-of-care diagnostics.

Biomed Opt Express 2020 Apr 9;11(4):1864-1875. Epub 2020 Mar 9.

EPSRC Proteus IRC Hub in Optical Molecular Sensing and Imaging, Centre for Inflammation Research, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, EH16 4TJ, UK.

Infectious diseases are the leading cause of morbidity and mortality in low and middle income countries (LMICs). Rapid diagnosis of infections in LMICs presents many challenges, especially in rural areas where access to health care, including diagnostics, is poor. Microscopy is one of the most commonly used platforms to diagnose bacterial infections on clinical samples. Read More

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http://dx.doi.org/10.1364/BOE.381014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173883PMC

Polarimetric second-harmonic generation microscopy of the hierarchical structure of collagen in stage I-III non-small cell lung carcinoma.

Biomed Opt Express 2020 Apr 9;11(4):1851-1863. Epub 2020 Mar 9.

Department of Physics, University of Toronto, 60 St. George St, Toronto, M5S 1A7, Canada.

Polarimetric second-harmonic generation (P-SHG) microscopy is used to quantify the structural alteration of collagen in stage-I,-II and -III non-small cell lung carcinoma (NSCLC) tissue. The achiral and chiral molecular second-order susceptibility tensor components ratios ( and , respectively), the degree of linear polarization () and the in-plane collagen fiber orientation () were extracted. Further, texture analysis was performed on the SHG intensity, , , and . Read More

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http://dx.doi.org/10.1364/BOE.387744DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173881PMC

Automated morphometric measurement of the retinal pigment epithelium complex and choriocapillaris using swept source OCT.

Biomed Opt Express 2020 Apr 6;11(4):1834-1850. Epub 2020 Mar 6.

Department of Bioengineering, University of Washington, Seattle, WA 98105, USA.

We report the development of an automated method to measure morphological features of the retinal pigment epithelium (RPE), Bruch's membrane (BM) and choriocapillaris (CC) using a commercially available swept source OCT (SS-OCT) system. The locations of the inner segment/outer segment (IS/OS), RPE and CC were determined by optical coherence tomography (OCT) and OCT angiography (OCTA) A-scan intensity profiles, which were used to calculate the mean IS/OS-to-RPE distance, mean RPE-to-CC distance, mean RPE-to-CC outer boundary distance, mean RPE thickness and mean CC thickness across the entire scan volume. The automated method was tested on two groups of normal subjects: younger age group (n=20, 30. Read More

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http://dx.doi.org/10.1364/BOE.385113DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173887PMC
April 2020
3.648 Impact Factor

Study on the chemodrug-induced effect in nasopharyngeal carcinoma cells using laser tweezer Raman spectroscopy.

Biomed Opt Express 2020 Apr 5;11(4):1819-1833. Epub 2020 Mar 5.

Key Laboratory of Optoelectronic Science and Technology for Medicine, Ministry of Education and Fujian Provincial Key Laboratory for Photonics Technology, Fujian Normal University, Fuzhou 350007, China.

To explore the effect in nasopharyngeal carcinoma (NPC) cells after treatment with chemodrugs, Raman profiles were characterized by laser tweezer Raman spectroscopy. Two NPC cell lines (CNE2 and C666-1) were treated with gemcitabine, cisplatin, and paclitaxel, respectively. The high-quality Raman spectra of cells without or with treatments were recorded at the single-cell level with label-free laser tweezers Raman spectroscopy (LTRS) and analyzed for the differences of alterations of Raman profiles. Read More

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http://dx.doi.org/10.1364/BOE.388785DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173897PMC
April 2020
3.648 Impact Factor

Generative optical modeling of whole blood for detecting platelets in lens-free images.

Biomed Opt Express 2020 Apr 5;11(4):1808-1818. Epub 2020 Mar 5.

Johns Hopkins University, Baltimore, MD 21218, USA.

In this paper, we consider the task of detecting platelets in images of diluted whole blood taken with a lens-free microscope. Despite having several advantages over traditional microscopes, lens-free imaging systems have the significant challenge that the resolution of the system is typically limited by the pixel dimensions of the image sensor. As a result of this limited resolution, detecting platelets is very difficult even by manual inspection of the images due to the fact that platelets occupy just a few pixels of the reconstructed image. Read More

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http://dx.doi.org/10.1364/BOE.382280DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173916PMC

Combined Nd:YAG and Er:YAG lasers for real-time closed-loop tissue-specific laser osteotomy.

Biomed Opt Express 2020 Apr 4;11(4):1790-1807. Epub 2020 Mar 4.

Biomedical Laser and Optics Group (BLOG), Department of Biomedical Engineering, University of Basel, CH-4123 Allschwil, Switzerland.

A novel real-time and non-destructive method for differentiating soft from hard tissue in laser osteotomy has been introduced and tested in a closed-loop fashion. Two laser beams were combined: a low energy frequency-doubled nanosecond Nd:YAG for detecting the type of tissue, and a high energy microsecond Er:YAG for ablating bone. The working principle is based on adjusting the energy of the Nd:YAG laser until it is low enough to create a microplasma in the hard tissue only (different energies are required to create plasma in different tissue types). Read More

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http://dx.doi.org/10.1364/BOE.385862DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173907PMC

Analysis of longitudinal sections of retinal vessels using Doppler OCT.

Biomed Opt Express 2020 Apr 4;11(4):1772-1789. Epub 2020 Mar 4.

Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, 1090, Austria.

We present a new method for imaging retinal vessels that provides both structural and hemodynamic information. Our technique is based on a single beam OCT system with an integrated retinal tracker that enables recording of arbitrary scan patterns. We record longitudinal sections along the traces of retinal vessels. Read More

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http://dx.doi.org/10.1364/BOE.385938DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173918PMC

Phase unwrapping based on a residual en-decoder network for phase images in Fourier domain Doppler optical coherence tomography.

Biomed Opt Express 2020 Apr 3;11(4):1760-1771. Epub 2020 Mar 3.

School of Optics and Photonics, Beijing Institute of Technology, No. 5 South Zhongguancun Street, Haidian, Beijing 100081, China.

To solve the phase unwrapping problem for phase images in Fourier domain Doppler optical coherence tomography (DOCT), we propose a deep learning-based residual en-decoder network (REDN) method. In our approach, we reformulate the definition for obtaining the true phase as obtaining an integer multiple of 2 at each pixel by semantic segmentation. The proposed REDN architecture can provide recognition performance with pixel-level accuracy. Read More

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http://dx.doi.org/10.1364/BOE.386101DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173896PMC
April 2020
3.648 Impact Factor

Large-scale label-free single-cell analysis of paramylon in by high-throughput broadband Raman flow cytometry.

Biomed Opt Express 2020 Apr 3;11(4):1752-1759. Epub 2020 Mar 3.

Department of Chemistry, The University of Tokyo, Tokyo 113-0033, Japan.

Microalga-based biomaterial production has attracted attention as a new source of drugs, foods, and biofuels. For enhancing the production efficiency, it is essential to understand its differences between heterogeneous microalgal subpopulations. However, existing techniques are not adequate to address the need due to the lack of single-cell resolution or the inability to perform large-scale analysis and detect small molecules. Read More

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http://dx.doi.org/10.1364/BOE.382957DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173913PMC

Laser fluorescence spectroscopy in predicting the formation of a keloid scar: preliminary results and the role of lipopigments.

Biomed Opt Express 2020 Apr 2;11(4):1742-1751. Epub 2020 Mar 2.

Moscow Regional Research and Clinical Institute, 61/2 Shchepkina str., Moscow, 129110, Russia.

Keloid scars, in contrast to other scar types, significantly reduce the patient's quality of life. To develop a nondestructive optical diagnostic technique predicting the keloid scars formation , laser-induced fluorescence spectroscopy (LFS) was used to study the autofluorescence in skin of patients with various types of head and neck cicatricial deformities. The unexpected results were obtained for the endogenous fluorescence of lipofuscin. Read More

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http://dx.doi.org/10.1364/BOE.386029DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173908PMC

Prefrontal functional connectivity analysis of cognitive decline for early diagnosis of mild cognitive impairment: a functional near-infrared spectroscopy study.

Biomed Opt Express 2020 Apr 2;11(4):1725-1741. Epub 2020 Mar 2.

Department of Information and Communication Engineering, DGIST, Daegu 42988, South Korea.

Cognitive decline (CD) is a major symptom of mild cognitive impairment (MCI). Patients with MCI have an increased likelihood of developing Alzheimer's disease (AD). Although a cure for AD is currently lacking, medication therapies and/or daily training in the early stage can alleviate disease progression and improve patients' quality of life. Read More

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http://dx.doi.org/10.1364/BOE.382197DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173911PMC

The Valsalva maneuver: an indispensable physiological tool to differentiate intra versus extracranial near-infrared signal.

Biomed Opt Express 2020 Apr 2;11(4):1712-1724. Epub 2020 Mar 2.

National Institute for Health Research Surgical Reconstruction and Microbiology Research Centre (NIHR SRMRC), University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK.

Developing near-infrared spectroscopy (NIRS) parameter recovery techniques to more specifically resolve brain physiology from that of the overlying tissue is an important part of improving the clinical utility of the technology. The Valsalva maneuver (VM) involves forced expiration against a closed glottis causing widespread venous congestion within the context of a fall in cardiac output. Due to the specific anatomical confines and metabolic demands of the brain we believe a properly executed VM has the ability to separate haemodynamic activity of brain tissue from that of the overlying scalp as observed by NIRS, and confirmed by functional magnetic resonance imaging (fMRI). Read More

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http://dx.doi.org/10.1364/BOE.11.001712DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7173884PMC
April 2020
3.648 Impact Factor

25 Anniversary of STED Microscopy and the 20 Anniversary of SIM: feature introduction.

Biomed Opt Express 2020 Mar 28;11(3):1707-1711. Epub 2020 Feb 28.

Quantitative Imaging Group, Delft University of Technology, Delft, Netherlands.

This feature issue commemorating 25 years of STED microscopy and 20 years of SIM is intended to highlight the incredible progress and growth in the field of superresolution microscopy since Stefan Hell and Jan Wichmann published the article Breaking the diffraction resolution limit by stimulated emission: stimulated-emission-depletion fluorescence microscopy in Optics Letters in 1994. Read More

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http://dx.doi.org/10.1364/BOE.391490DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7075616PMC

Optical characterization of porcine tissues from various organs in the 650-1100 nm range using time-domain diffuse spectroscopy.

Biomed Opt Express 2020 Mar 28;11(3):1697-1706. Epub 2020 Feb 28.

Dipartimento di Fisica, Politecnico di Milano, Milano, Italy.

We present a systematic characterization of the optical properties (µ and µ') of nine representative ex vivo porcine tissues over a broadband spectrum (650-1100 nm). We applied time-resolved diffuse optical spectroscopy measurements for recovering the optical properties of porcine tissues depicting a realistic representation of the tissue heterogeneity and morphology likely to be found in different ex vivo tissues. The results demonstrate a large spectral and inter-tissue variation of optical properties. Read More

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http://dx.doi.org/10.1364/BOE.386349DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7075607PMC

Predictive model for the quantitative analysis of human skin using photothermal radiometry and diffuse reflectance spectroscopy.

Biomed Opt Express 2020 Mar 28;11(3):1679-1696. Epub 2020 Feb 28.

Department of Complex Matter, Jožef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia.

We have recently introduced a novel methodology for the noninvasive analysis of the structure and composition of human skin . The approach combines pulsed photothermal radiometry (PPTR), involving time-resolved measurements of mid-infrared emission after irradiation with a millisecond light pulse, and diffuse reflectance spectroscopy (DRS) in the visible part of the spectrum. Simultaneous fitting of both data sets with respective predictions from a numerical model of light transport in human skin enables the assessment of the contents of skin chromophores (melanin, oxy-, and deoxy-hemoglobin), as well as scattering properties and thicknesses of the epidermis and dermis. Read More

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http://dx.doi.org/10.1364/BOE.384982DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7075612PMC

Design of a high-resolution light field miniscope for volumetric imaging in scattering tissue.

Biomed Opt Express 2020 Mar 28;11(3):1662-1678. Epub 2020 Feb 28.

Department of Electrical and Computer Engineering, Boston University, Boston, MA 02215, USA.

Integrating light field microscopy techniques with existing miniscope architectures has allowed for volumetric imaging of targeted brain regions in freely moving animals. However, the current design of light field miniscopes is limited by non-uniform resolution and long imaging path length. In an effort to overcome these limitations, this paper proposes an optimized Galilean-mode light field miniscope (Gali-MiniLFM), which achieves a more consistent resolution and a significantly shorter imaging path than its conventional counterparts. Read More

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http://dx.doi.org/10.1364/BOE.384673DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7075622PMC

Deep learning in single-molecule microscopy: fundamentals, caveats, and recent developments [Invited].

Biomed Opt Express 2020 Mar 27;11(3):1633-1661. Epub 2020 Feb 27.

Department of Chemistry, Stanford University, Stanford, CA 94305, USA.

Deep learning-based data analysis methods have gained considerable attention in all fields of science over the last decade. In recent years, this trend has reached the single-molecule community. In this review, we will survey significant contributions of the application of deep learning in single-molecule imaging experiments. Read More

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http://dx.doi.org/10.1364/BOE.386361DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7075610PMC

Wide-vergence, multi-spectral adaptive optics scanning laser ophthalmoscope with diffraction-limited illumination and collection.

Biomed Opt Express 2020 Mar 26;11(3):1617-1632. Epub 2020 Feb 26.

School of Optometry and Vision Science Graduate Group, University of California Berkeley; Berkeley, CA 94720, USA.

Visualizing and assessing the function of microscopic retinal structures in the human eye is a challenging task that has been greatly facilitated by ophthalmic adaptive optics (AO). Yet, as AO imaging systems advance in functionality by employing multiple spectral channels and larger vergence ranges, achieving optimal resolution and signal-to-noise ratios (SNR) becomes difficult and is often compromised. While current-generation AO retinal imaging systems have demonstrated excellent, near diffraction-limited imaging performance over wide vergence and spectral ranges, a full theoretical and experimental analysis of an AOSLO that includes both the light delivery and collection optics has not been done, and neither has the effects of extending wavefront correction from one wavelength to imaging performance in different spectral channels. Read More

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http://dx.doi.org/10.1364/BOE.384229DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7075605PMC

Towards real-time wide-field fluorescence lifetime imaging of 5-ALA labeled brain tumors with multi-tap CMOS cameras.

Biomed Opt Express 2020 Mar 26;11(3):1598-1616. Epub 2020 Feb 26.

Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, 1090 Vienna, Austria.

Fluorescence guided neurosurgery based on 5-aminolevulinic acid (5-ALA) has significantly increased maximal safe resections. Fluorescence lifetime imaging (FLIM) of 5-ALA could further boost this development by its increased sensitivity. However, neurosurgeons require real-time visual feedback which was so far limited in dual-tap CMOS camera based FLIM. Read More

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http://dx.doi.org/10.1364/BOE.382817DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7075617PMC