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    2496 results match your criteria Biomedical optics express[Journal]

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    Highly phase-stable 200 kHz swept-source optical coherence tomography based on KTN electro-optic deflector.
    Biomed Opt Express 2017 Aug 18;8(8):3687-3699. Epub 2017 Jul 18.
    Department of Electrical Engineering, Columbia University, 500 W 120th St., New York, New York 10027, USA.
    The rapid advance in swept-source optical coherence tomography (SS-OCT) technology has enabled exciting new applications in elastography, angiography, and vibrometry, where both high temporal resolution and phase stability are highly sought-after. In this paper, we present a 200 kHz SS-OCT system centered at 1321 nm by using an electro-optically tuned swept source. The proposed system's performance was fully characterized, and it possesses superior phase stability (0. Read More

    Custom built nonlinear optical crosslinking (NLO CXL) device capable of producing mechanical stiffening in ex vivo rabbit corneas.
    Biomed Opt Express 2017 Oct 29;8(10):4788-4797. Epub 2017 Sep 29.
    Department of Biomedical Engineering, University of California, Irvine, Irvine, CA, USA.
    The purpose of this study was to develop and test a nonlinear optical device to photoactivate riboflavin to produce spatially controlled collagen crosslinking and mechanical stiffening within the cornea. A nonlinear optical device using a variable numerical aperture objective was built and coupled to a Chameleon femtosecond laser. Ex vivo rabbit eyes were then saturated with riboflavin and scanned with various scanning parameters over a 4 mm area in the central cornea. Read More

    Chromophore decomposition in multispectral time-resolved diffuse optical tomography.
    Biomed Opt Express 2017 Oct 28;8(10):4772-4787. Epub 2017 Sep 28.
    Univ. Grenoble Alpes, F-38000 Grenoble, France, CEA, LETI, MINATEC Campus, F-38054 Grenoble, France.
    Multicomponent phantom measurements are carried out to evaluate the ability of multispectral time domain diffuse optical tomography in reflectance geometry to quantify the position and the composition of small heterogeneities at depths of 1-1.5 cm in turbid media. Time-resolved data were analyzed with the Mellin-Laplace transform. Read More

    Analysis of poration-induced changes in cells from laser-activated plasmonic substrates.
    Biomed Opt Express 2017 Oct 27;8(10):4756-4771. Epub 2017 Sep 27.
    John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA.
    Laser-exposed plasmonic substrates permeabilize the plasma membrane of cells when in close contact to deliver cell-impermeable cargo. While studies have determined the cargo delivery efficiency and viability of laser-exposed plasmonic substrates, morphological changes in a cell have not been quantified. We porated myoblast C2C12 cells on a plasmonic pyramid array using a 532-nm laser with 850-ps pulse length and time-lapse fluorescence imaging to quantify cellular changes. Read More

    Label free monitoring of megakaryocytic development and proplatelet formation in vitro.
    Biomed Opt Express 2017 Oct 27;8(10):4742-4755. Epub 2017 Sep 27.
    Department of Biomedical Engineering, Tufts University, 4 Colby St., 02155 Medford MA, USA.
    Megakaryopoiesis and platelet production are complex biological processes that require tight regulation of successive lineage commitment steps and are ultimately responsible for maintaining and renewing the pool of circulating platelets in the blood. Despite major advancements in the understanding of megakaryocytic biology, the detailed mechanisms driving megakaryocytic differentiation have yet to be elucidated. Here we show that automated image analysis algorithms applied to two-photon excited fluorescence (TPEF) images can non-invasively monitor structural and metabolic megakaryocyte behavior changes occurring during differentiation and platelet formation in vitro. Read More

    Automated segmentation and quantification of airway mucus with endobronchial optical coherence tomography.
    Biomed Opt Express 2017 Oct 26;8(10):4729-4741. Epub 2017 Sep 26.
    Division of Pulmonary and Critical Care Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA.
    We propose a novel suite of algorithms for automatically segmenting the airway lumen and mucus in endobronchial optical coherence tomography (OCT) data sets, as well as a novel approach for quantifying the contents of the mucus. Mucus and lumen were segmented using a robust, multi-stage algorithm that requires only minimal input regarding sheath geometry. The algorithm performance was highly accurate in a wide range of airway and noise conditions. Read More

    There is more to accommodation of the eye than simply minimizing retinal blur.
    Biomed Opt Express 2017 Oct 26;8(10):4717-4728. Epub 2017 Sep 26.
    State College of Optometry, State University of New York, New York, USA.
    Eyes of children and young adults change their optical power to focus nearby objects at the retina. But does accommodation function by trial and error to minimize blur and maximize contrast as is generally accepted? Three experiments in monocular and monochromatic vision were performed under two conditions while aberrations were being corrected. In the first condition, feedback was available to the eye from both optical vergence and optical blur. Read More

    In vivo cellular-level real-time pharmacokinetic imaging of free-form and liposomal indocyanine green in liver.
    Biomed Opt Express 2017 Oct 26;8(10):4706-4716. Epub 2017 Sep 26.
    Graduate School of Nanoscience and Technology, Korea Advanced Institute of Science and Technology (KAIST), 291 Deahak-ro, Yuseong-gu, Daejeon, 34141, South Korea.
    Indocyanine green (ICG) is a near-infrared fluorophore approved for human use which has been widely used for various clinical applications. Despite the well-established clinical usage, our understanding about the microscopic in vivo pharmacokinetics of systemically administered ICG has been relatively limited. In this work, we successfully visualized real-time in vivo pharmacokinetic dynamics of the intravenously injected free-form and liposomal ICG in cellular resolution by utilizing a custom-built video-rate near infrared laser-scanning confocal microscopy system. Read More

    Efficient quantitative phase microscopy using programmable annular LED illumination.
    Biomed Opt Express 2017 Oct 26;8(10):4687-4705. Epub 2017 Sep 26.
    School of Electronic and Optical Engineering, Nanjing University of Science and Technology, No. 200 Xiaolingwei Street, Nanjing, Jiangsu Province 210094, China.
    In this work, we present an efficient quantitative phase imaging (QPI) approach using programmable annular LED illumination. As a new type of coded light source, the LED array provides flexible illumination control for noninterferometric QPI based on a traditional microscopic configurations. The proposed method modulates the transfer function of system by changing the LED illumination pattern, which provides noise-robust response of transfer function and achieves twice resolution limit of objective NA. Read More

    Self-prior strategy for organ reconstruction in fluorescence molecular tomography.
    Biomed Opt Express 2017 Oct 25;8(10):4671-4686. Epub 2017 Sep 25.
    Tsinghua University, School of Medicine, Department of Biomedical Engineering, Beijing 100084, China.
    The purpose of this study is to propose a strategy for organ reconstruction in fluorescence molecular tomography (FMT) without prior information from other imaging modalities, and to overcome the high cost and ionizing radiation caused by the traditional structural prior strategy. The proposed strategy is designed as an iterative architecture to solve the inverse problem of FMT. In each iteration, a short time Fourier transform (STFT) based algorithm is used to extract the self-prior information in the space-frequency energy spectrum with the assumption that the regions with higher fluorescence concentration have larger energy intensity, then the cost function of the inverse problem is modified by the self-prior information, and lastly an iterative Laplacian regularization algorithm is conducted to solve the updated inverse problem and obtains the reconstruction results. Read More

    Characterization of the mechanical properties of resected porcine organ tissue using optical fiber photoelastic polarimetry.
    Biomed Opt Express 2017 Oct 25;8(10):4663-4670. Epub 2017 Sep 25.
    Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, 90089, USA.
    Characterizing the mechanical behavior of living tissue presents an interesting challenge because the elasticity varies by eight orders of magnitude, from 50Pa to 5GPa. In the present work, a non-destructive optical fiber photoelastic polarimetry system is used to analyze the mechanical properties of resected samples from porcine liver, kidney, and pancreas. Using a quasi-linear viscoelastic fit, the elastic modulus values of the different organ systems are determined. Read More

    Optophysiology of cardiomyocytes: characterizing cellular motion with quantitative phase imaging.
    Biomed Opt Express 2017 Oct 22;8(10):4652-4662. Epub 2017 Sep 22.
    Department of Ophthalmology, Stanford University, Stanford, CA, 94305, USA.
    Quantitative phase imaging enables precise characterization of cellular shape and motion. Variation of cell volume in populations of cardiomyocytes can help distinguish their types, while changes in optical thickness during beating cycle identify contraction and relaxation periods and elucidate cell dynamics. Parameters such as characteristic cycle shape, beating frequency, duration and regularity can be used to classify stem-cell derived cardiomyocytes according to their health and, potentially, cell type. Read More

    Non-invasive monitoring of skin inflammation using an oxygen-sensing paint-on bandage.
    Biomed Opt Express 2017 Oct 22;8(10):4640-4651. Epub 2017 Sep 22.
    Wellman Center for Photomedicine, Harvard Medical School, Massachusetts General Hospital, 149 13th Street, Charlestown, Massachusetts 02129, USA.
    Inflammation involves a cascade of cellular and molecular mediators that ultimately lead to the infiltration of immune cells into the affected area. This inflammatory process in skin is common to many diseases including acne, infection, and psoriasis, with the presence or absence of immune cells a potential diagnostic marker. Here we show that skin inflammation can be non-invasively measured and mapped using a paint-on oxygen sensing bandage in an in vivo porcine inflammation model. Read More

    Comparison and combination of rotational imaging optical coherence tomography and selective plane illumination microscopy for embryonic study.
    Biomed Opt Express 2017 Oct 22;8(10):4629-4639. Epub 2017 Sep 22.
    Department of Biomedical Engineering, University of Houston, Houston, TX 77204, USA.
    Several optical imaging techniques have been applied for high-resolution embryonic imaging using different contrast mechanisms, each with their own benefits and limitations. In this study, we imaged the same E9.5 mouse embryo with rotational imaging optical coherence tomography (RI-OCT) and selective plane illumination microscopy (SPIM). Read More

    Intra-ocular lens optical changes resulting from the loading of dexamethasone.
    Biomed Opt Express 2017 Oct 21;8(10):4621-4628. Epub 2017 Sep 21.
    Instituto de Bioingeniería, Universidad Miguel Hernández and CIBER BBN, Elche, Spain.
    To study the optical changes on hydrogel-silicone intraocular lenses (IOLs) resulting from loading them with dexamethasone. We used prototype hydrogel(pHEMA)-silicone IOLs and loaded the matrices with an anti-inflammatory drug (dexamethasone). The optical properties we analyzed experimentally were a) modulation transfer function (MTF); b) spectral transmission; c) diopter power. Read More

    Fitting-free algorithm for efficient quantification of collagen fiber alignment in SHG imaging applications.
    Biomed Opt Express 2017 Oct 20;8(10):4609-4620. Epub 2017 Sep 20.
    Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21205 USA.
    Collagen fiber alignment derived from second harmonic generation (SHG) microscopy images can be important for disease diagnostics. Image processing algorithms are needed to robustly quantify the alignment in images with high sensitivity and reliability. Fourier transform (FT) magnitude, 2D power spectrum, and image autocorrelation have previously been used to extract fiber information from images by assuming a certain mathematical model (e. Read More

    Angiographic and structural imaging using high axial resolution fiber-based visible-light OCT.
    Biomed Opt Express 2017 Oct 20;8(10):4595-4608. Epub 2017 Sep 20.
    Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA.
    Optical coherence tomography using visible-light sources can increase the axial resolution without the need for broader spectral bandwidth. Here, a high-resolution, fiber-based, visible-light optical coherence tomography system is built and used to image normal retina in rats and blood vessels in chicken embryo. In the rat retina, accurate segmentation of retinal layer boundaries and quantification of layer thicknesses are accomplished. Read More

    ELHnet: a convolutional neural network for classifying cochlear endolymphatic hydrops imaged with optical coherence tomography.
    Biomed Opt Express 2017 Oct 20;8(10):4579-4594. Epub 2017 Sep 20.
    USC Caruso Department of Otolaryngology-Head and Neck Surgery, 1540 Alcazar, Suite 204M, Los Angeles, CA 90033, USA.
    Detection of endolymphatic hydrops is important for diagnosing Meniere's disease, and can be performed non-invasively using optical coherence tomography (OCT) in animal models as well as potentially in the clinic. Here, we developed ELHnet, a convolutional neural network to classify endolymphatic hydrops in a mouse model using learned features from OCT images of mice cochleae. We trained ELHnet on 2159 training and validation images from 17 mice, using only the image pixels and observer-determined labels of endolymphatic hydrops as the inputs. Read More

    Millisecond infrared laser pulses depolarize and elicit action potentials on in-vitro dorsal root ganglion neurons.
    Biomed Opt Express 2017 Oct 19;8(10):4568-4578. Epub 2017 Sep 19.
    Institut d'Electronique et des Systèmes, CNRS UMR5214, Université de Montpellier, Montpellier, France.
    This work focuses on the optical stimulation of dorsal root ganglion (DRG) neurons through infrared laser light stimulation. We show that a few millisecond laser pulse at 1875 nm induces a membrane depolarization, which was observed by the patch-clamp technique. This stimulation led to action potentials firing on a minority of neurons beyond an energy threshold. Read More

    Vascular patterning of subcutaneous mouse fibrosarcomas expressing individual VEGF isoforms can be differentiated using angiographic optical coherence tomography.
    Biomed Opt Express 2017 Oct 19;8(10):4551-4567. Epub 2017 Sep 19.
    Biophotonics Group, Kroto Research Institute, University of Sheffield, Sheffield, UK.
    Subcutaneously implanted experimental tumors in mice are commonly used in cancer research. Despite their superficial location, they remain a challenge to image non-invasively at sufficient spatial resolution for microvascular studies. Here we evaluate the capabilities of optical coherence tomography (OCT) angiography for imaging such tumors directly through the murine skin in-vivo. Read More

    Simultaneously extracting multiple parameters via multi-distance and multi-exposure diffuse speckle contrast analysis.
    Biomed Opt Express 2017 Oct 19;8(10):4537-4550. Epub 2017 Sep 19.
    School of Science, Nanjing University of Science and Technology, No.200 Xiaolingwei Street, Nanjing 210094, China.
    Recent advancements in diffuse speckle contrast analysis (DSCA) have opened the path for noninvasive acquisition of deep tissue microvasculature blood flow. In fact, in addition to blood flow index αDB , the variations of tissue optical absorption μa , reduced scattering coefficients [Formula: see text], as well as coherence factor β can modulate temporal fluctuations of speckle patterns. In this study, we use multi-distance and multi-exposure DSCA (MDME-DSCA) to simultaneously extract multiple parameters such as μa , [Formula: see text], αDB , and β. Read More

    Analysis of the potential for non-invasive imaging of oxygenation at heart depth, using ultrasound optical tomography (UOT) or photo-acoustic tomography (PAT).
    Biomed Opt Express 2017 Oct 19;8(10):4523-4536. Epub 2017 Sep 19.
    Department of Physics, Lund University, 221 00 Lund, Sweden.
    Despite the important medical implications, it is currently an open task to find optical non-invasive techniques that can image deep organs in humans. Addressing this, photo-acoustic tomography (PAT) has received a great deal of attention in the past decade, owing to favorable properties like high contrast and high spatial resolution. However, even with optimal components PAT cannot penetrate beyond a few centimeters, which still presents an important limitation of the technique. Read More

    Human iris three-dimensional imaging at micron resolution by a micro-plenoptic camera.
    Biomed Opt Express 2017 Oct 14;8(10):4514-4522. Epub 2017 Sep 14.
    Department of Mechanical Engineering, University of Michigan, 1231 Beal Avenue, Ann Arbor, MI 48109, USA.
    A micro-plenoptic system was designed to capture the three-dimensional (3D) topography of the anterior iris surface by simple single-shot imaging. Within a depth-of-field of 2.4 mm, depth resolution of 10 µm can be achieved with accuracy (systematic errors) and precision (random errors) below 20%. Read More

    Examination of Drosophila eye development with third harmonic generation microscopy.
    Biomed Opt Express 2017 Oct 14;8(10):4504-4513. Epub 2017 Sep 14.
    Department of Biology, University of Toronto Mississauga, 3359 Mississauga Road, Mississauga, Ontario L5L 1C6, Canada.
    Third harmonic generation (THG) microscopy can exploit endogenous harmonophores such as pigment macromolecules for enhanced image contrast, and therefore can be used without exogenous contrast agents. Previous studies have established that carotenoid compounds are ideal harmonophores for THG microscopy; we therefore sought to determine whether THG from endogenous carotenoid-derived compounds, such as retinal in photoreceptor cells, could serve as a new label-free method for developmental studies. Here we study the development of the pupal eye in Drosophila melanogaster and determine the localization of rhodopsin using THG microscopy technique. Read More

    Robust tracking of respiratory rate in high-dynamic range scenes using mobile thermal imaging.
    Biomed Opt Express 2017 Oct 13;8(10):4480-4503. Epub 2017 Sep 13.
    Interaction Centre, Faculty of Brain Sciences, University College London, London, WC1E 6BT, UK.
    The ability to monitor the respiratory rate, one of the vital signs, is extremely important for the medical treatment, healthcare and fitness sectors. In many situations, mobile methods, which allow users to undertake everyday activities, are required. However, current monitoring systems can be obtrusive, requiring users to wear respiration belts or nasal probes. Read More

    Automated red blood cells extraction from holographic images using fully convolutional neural networks.
    Biomed Opt Express 2017 Oct 12;8(10):4466-4479. Epub 2017 Sep 12.
    Department of Electrical and Computer Engineering, University of Connecticut, Storrs, CT 06269, USA.
    In this paper, we present two models for automatically extracting red blood cells (RBCs) from RBCs holographic images based on a deep learning fully convolutional neural network (FCN) algorithm. The first model, called FCN-1, only uses the FCN algorithm to carry out RBCs prediction, whereas the second model, called FCN-2, combines the FCN approach with the marker-controlled watershed transform segmentation scheme to achieve RBCs extraction. Both models achieve good segmentation accuracy. Read More

    Tissue-like phantoms for quantitative birefringence imaging.
    Biomed Opt Express 2017 Oct 12;8(10):4454-4465. Epub 2017 Sep 12.
    Wellman Center for Photomedicine, Harvard Medical School and Massachusetts General Hospital, 40 Blossom Street, Boston, MA 02114, USA.
    Birefringence imaging, including polarization sensitive optical coherence tomography (PS-OCT), can provide valuable insight into the microscopic structure and organization of many biological tissues. In this paper, we report on a method to fabricate tissue-like birefringence phantoms for such imaging modalities. We utilize the photo-elastic effect, wherein birefringence is induced by stretching a polymer sample after heating it above its glass-transition temperature. Read More

    Flow-through micro-capillary refractive index sensor based on T/R spectral shift monitoring.
    Biomed Opt Express 2017 Oct 11;8(10):4438-4453. Epub 2017 Sep 11.
    Dipartimento di Ingegneria Industriale e dell'Informazione, University of Pavia, 27100, Pavia, Italy.
    We present a flow-through refractive index sensor for measuring the concentration of glucose solutions based on the application of rectangular glass micro-capillaries, with channel depth of 50 µm and 30 µm. A custom designed and 3D printed polymeric shell protects the tiny capillaries, ensuring an easier handling and interconnection with the macro-fluidic path. By illuminating the capillary with broadband radiation centered at λ~1. Read More

    Label-free sensing of the binding state of MUC1 peptide and anti-MUC1 aptamer solution in fluidic chip by terahertz spectroscopy.
    Biomed Opt Express 2017 Oct 11;8(10):4427-4437. Epub 2017 Sep 11.
    Department of Laboratory Medicine, Southwest Hospital, Third Military Medical University, Chongqing 400038, China.
    The aptamer and target molecule binding reaction has been widely applied for construction of aptasensors, most of which are labeled methods. In contrast, terahertz technology proves to be a label-free sensing tool for biomedical applications. We utilize terahertz absorption spectroscopy and molecular dynamics simulation to investigate the variation of binding-induced collective vibration of hydrogen bond network in a mixed solution of MUC1 peptide and anti-MUC1 aptamer. Read More

    Optical imaging for the assessment of hepatocyte metabolic state in ischemia and reperfusion injuries.
    Biomed Opt Express 2017 Oct 8;8(10):4419-4426. Epub 2017 Sep 8.
    Biopotonics Lab, Electrical Engineering Department, University of Wisconsin - Milwaukee, 3200 N Cramer St, Milwaukee, WI 53211, USA.
    Deterioration in mitochondrial function leads to hepatic ischemia and reperfusion injury (IRI) in liver surgery and transplantation. 3D optical cryoimaging was used to measure the levels of mitochondrial coenzymes NADH and FAD, and their redox ratio (NADH/FAD) gave a quantitative marker for hepatocyte oxidative stress during IRI. Using a rat model, five groups were compared: control, ischemia for 60 or 90 minutes (Isc60, Isc90), ischemia for 60 or 90 minutes followed by reperfusion of 24 hours (IRI60, IRI90). Read More

    Generation and optimization of superpixels as image processing kernels for Jones matrix optical coherence tomography.
    Biomed Opt Express 2017 Oct 8;8(10):4396-4418. Epub 2017 Sep 8.
    Computational Optics Group, University of Tsukuba, Tennodai 1-1-1, Tsukuba, Ibaraki 305-8573, Japan.
    Jones matrix-based polarization sensitive optical coherence tomography (JM-OCT) simultaneously measures optical intensity, birefringence, degree of polarization uniformity, and OCT angiography. The statistics of the optical features in a local region, such as the local mean of the OCT intensity, are frequently used for image processing and the quantitative analysis of JM-OCT. Conventionally, local statistics have been computed with fixed-size rectangular kernels. Read More

    Quantitative photoacoustic tomography augmented with surface light measurements.
    Biomed Opt Express 2017 Oct 8;8(10):4380-4395. Epub 2017 Sep 8.
    Department of Applied Physics, University of Eastern Finland, P.O. Box 1627, 70211 Kuopio, Finland.
    Quantitative photoacoustic tomography is an imaging modality in which distributions of optical parameters inside tissue are estimated from photoacoustic images. This optical parameter estimation is an ill-posed problem and it needs to be approached in the framework of inverse problems. In this work, utilising surface light measurements in quantitative photoacoustic tomography is studied. Read More

    Rapid adaptive remote focusing microscope for sensing of volumetric neural activity.
    Biomed Opt Express 2017 Oct 7;8(10):4369-4379. Epub 2017 Sep 7.
    Centre for Neural Circuits and Behaviour, University of Oxford, Mansfield Road, Oxford OX1 3SR, UK.
    The ability to record neural activity in the brain of a living organism at cellular resolution is of great importance for defining the neural circuit mechanisms that direct behavior. Here we present an adaptive two-photon microscope optimized for extraction of neural signals over volumes in intact Drosophila brains, even in the presence of specimen motion. High speed volume imaging was made possible through reduction of spatial resolution while maintaining the light collection efficiency of a high resolution, high numerical aperture microscope. Read More

    Angle-selective optical filter for highly sensitive reflection photoplethysmogram.
    Biomed Opt Express 2017 Oct 7;8(10):4361-4368. Epub 2017 Sep 7.
    Department of Bio and Brain Engineering and KAIST Institute for Health Science and Technology, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, South Korea.
    We report an angle-selective optical filter (ASOF) for highly sensitive reflection photoplethysmography (PPG) sensors. The ASOF features slanted aluminum (Al) micromirror arrays embedded in transparent polymer resin, which effectively block scattered light under human tissue. The device microfabrication was done by using geometry-guided resist reflow of polymer micropatterns, polydimethylsiloxane replica molding, and oblique angle deposition of thin Al film. Read More

    Noninvasive near infrared autofluorescence imaging of retinal pigment epithelial cells in the human retina using adaptive optics.
    Biomed Opt Express 2017 Oct 7;8(10):4348-4360. Epub 2017 Sep 7.
    National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA.
    The retinal pigment epithelial (RPE) cells contain intrinsic fluorophores that can be visualized using infrared autofluorescence (IRAF). Although IRAF is routinely utilized in the clinic for visualizing retinal health and disease, currently, it is not possible to discern cellular details using IRAF due to limits in resolution. We demonstrate that the combination of adaptive optics (AO) with IRAF (AO-IRAF) enables higher-resolution imaging of the IRAF signal, revealing the RPE mosaic in the living human eye. Read More

    Imaging of neuronal tissues by x-ray diffraction and x-ray fluorescence microscopy: evaluation of contrast and biomarkers for neurodegenerative diseases.
    Biomed Opt Express 2017 Oct 5;8(10):4331-4347. Epub 2017 Sep 5.
    Cluster of Excellence "Nanoscale Microscopy and Molecular Physiology of the Brain", Humboldtallee 23, 37073 Göttingen, Germany.
    We have used scanning X-ray diffraction (XRD) and X-ray fluorescence (XRF) with micro-focused synchrotron radiation to study histological sections from human substantia nigra (SN). Both XRF and XRD mappings visualize tissue properties, which are inaccessible by conventional microscopy and histology. We propose to use these advanced tools to characterize neuronal tissue in neurodegeneration, in particular in Parkinson's disease (PD). Read More

    POF-yarn weaves: controlling the light out-coupling of wearable phototherapy devices.
    Biomed Opt Express 2017 Oct 5;8(10):4316-4330. Epub 2017 Sep 5.
    Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Biomimetic Membranes and Textiles, Lerchenfeldstrasse 5, 9014 St. Gallen, Switzerland.
    Neonatal jaundice (hyperbilirubinaemia) is common in neonates and, often, intensive blue-light phototherapy is required to prevent long-term effects. A photonic textile can overcome three major incubator-related concerns: Insulation of the neonate, human contact, and usage restraints. This paper describes the development of a homogeneous luminous textile from polymer optical fibres to use as a wearable, long-term phototherapy device. Read More

    Mitotic tethers connect sister chromosomes and transmit "cross-polar" force during anaphase A of mitosis in PtK2 cells.
    Biomed Opt Express 2017 Oct 5;8(10):4310-4315. Epub 2017 Sep 5.
    Department of Bioengineering, University of California, San Diego, CA 92093, USA.
    Originally described in crane-fly spermatocytes, tethers physically link and transmit force between the ends of separating chromosomes. Optical tweezers and laser scissors were used to sever the tether between chromosomes, create chromosome fragments attached to the tether which move toward the opposite pole, and to trap the tethered fragments. Laser microsurgery in the intracellular space between separating telomeres reduced chromosome strain in half of tested chromosome pairs. Read More

    Combined multi-distance frequency domain and diffuse correlation spectroscopy system with simultaneous data acquisition and real-time analysis.
    Biomed Opt Express 2017 Sep 7;8(9):3993-4006. Epub 2017 Aug 7.
    Harvard Medical School, Massachusetts General Hospital, Martinos Center for Biomedical Imaging, 149 13th St., Charlestown, MA 02129, USA.
    Frequency domain near infrared spectroscopy (FD-NIRS) and diffuse correlation spectroscopy (DCS) have emerged as synergistic techniques for the non-invasive assessment of tissue health. Combining FD-NIRS oximetry with DCS measures of blood flow, the tissue oxygen metabolic rate can be quantified, a parameter more closely linked to underlying physiology and pathology than either NIRS or DCS estimates alone. Here we describe the first commercially available integrated instrument, called the "MetaOx", designed to enable simultaneous FD-NIRS and DCS measurements at rates of 10 + Hz, and offering real-time data evaluation. Read More

    High sensitivity optical measurement of skin gloss.
    Biomed Opt Express 2017 Sep 7;8(9):3981-3992. Epub 2017 Aug 7.
    Department of Personal Care and Wellness, Philips Research, 5656AE, Eindhoven, the Netherlands.
    We demonstrate a low-cost optical method for measuring the gloss properties with improved sensitivity in the low gloss regime, relevant for skin gloss properties. The gloss estimation method is based on, on the one hand, the slope of the intensity gradient in the transition regime between specular and diffuse reflection and on the other on the sum over the intensities of pixels above threshold, derived from a camera image obtained using unpolarized white light illumination. We demonstrate the improved sensitivity of the two proposed methods using Monte Carlo simulations and experiments performed on ISO gloss calibration standards with an optical prototype. Read More

    Wavelength-dependent optical properties of melanosomes in retinal pigmented epithelium and their changes with melanin bleaching: a numerical study.
    Biomed Opt Express 2017 Sep 7;8(9):3966-3980. Epub 2017 Aug 7.
    Department of Medicine, Boston University School of Medicine, Boston, MA 02118, USA.
    In this paper, we present the first numerical study on full metrics of wavelength-dependent optical properties of melanosomes in retinal pigmented epithelial (RPE) cells. T-matrix method was used to simulate the spheroidal shapes of mature melanosomes, and the complex refractive index was calculated by a subtractive Kramers-Kronig relation for melanin. The validity of the method was first confirmed by Mie theory, and corroborated by a comparison between visible light and near infrared (NIR) optical coherence tomography (OCT) on human retinal imaging. Read More

    Resolving adjacent nanophosphors of different concentrations by excitation-based cone-beam X-ray luminescence tomography.
    Biomed Opt Express 2017 Sep 4;8(9):3952-3965. Epub 2017 Aug 4.
    Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, Shaanxi 710032, China.
    Cone-beam X-ray luminescence computed tomography (CB-XLCT) has been proposed as a new molecular imaging modality recently. It can obtain both anatomical and functional tomographic images of an object efficiently, with the excitation of nanophosphors in vivo or in vitro by cone-beam X-rays. However, the ill-posedness of the CB-XLCT inverse problem degrades the image quality and makes it difficult to resolve adjacent luminescent targets with different concentrations, which is essential in the monitoring of nanoparticle metabolism and drug delivery. Read More

    All-optical photoacoustic projection imaging.
    Biomed Opt Express 2017 Sep 3;8(9):3938-3951. Epub 2017 Aug 3.
    Research Center for Non-Destructive Testing GmbH (RECENDT), Altenberger Straße 69, 4040 Linz, Austria.
    We introduce all-optical photoacoustic projection imaging. An array of fiber-optic interferometers is used to measure photoacoustic signals. The obtained images represent the projection of the three-dimensional spatial light absorbance within a sample onto a two-dimensional plane. Read More

    sideSPIM - selective plane illumination based on a conventional inverted microscope.
    Biomed Opt Express 2017 Sep 1;8(9):3918-3937. Epub 2017 Aug 1.
    Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California Irvine, Irvine, CA, USA.
    Previously described selective plane illumination microscopy techniques typically offset ease of use and sample handling for maximum imaging performance or vice versa. Also, to reduce cost and complexity while maximizing flexibility, it is highly desirable to implement light sheet microscopy such that it can be added to a standard research microscope instead of setting up a dedicated system. We devised a new approach termed sideSPIM that provides uncompromised imaging performance and easy sample handling while, at the same time, offering new applications of plane illumination towards fluidics and high throughput 3D imaging of multiple specimen. Read More

    Statistical model for OCT image denoising.
    Biomed Opt Express 2017 Sep 1;8(9):3903-3917. Epub 2017 Aug 1.
    King Abdullah University of science and Technology, Thuwal 23955-6900, Saudi Arabia.
    Optical coherence tomography (OCT) is a non-invasive technique with a large array of applications in clinical imaging and biological tissue visualization. However, the presence of speckle noise affects the analysis of OCT images and their diagnostic utility. In this article, we introduce a new OCT denoising algorithm. Read More

    Extended depth of focus intraocular lens: Chromatic performance.
    Biomed Opt Express 2017 Sep 31;8(9):4294-4309. Epub 2017 Aug 31.
    Departament d'Òptica i Optometria, Universitat Politècnica de Catalunya, BARCELONATECH Violinista Vellsolà 37, 08222 Terrassa, Spain.
    We describe a first-and-second-diffractive-order intraocular lens ((1(st),2(nd))DIOL) within the class of hybrid refractive-diffractive designs for intraocular lenses (IOLs) and analyse its properties of focus extension and compensation of longitudinal chromatic aberration (LCA), particularly for lenses with low addition. Power, energy efficiency and their wavelength dependence are extended from monofocal IOL and conventional bifocal zeroth-and-first-diffractive-order IOL ((0(th),1(st))DIOL) to (1(st),2(nd))DIOL of low addition. Compensation of LCA is experimentally assessed in optical bench through the through-focus energy efficiency of three Tecnis IOLs with red, green and blue illuminations: ZA9003 (monofocal), ZKB00 (bifocal (0(th),1(st))DIOL with + 2. Read More

    Accelerating nonlinear reconstruction in laminar optical tomography by use of recursive SVD inversion.
    Biomed Opt Express 2017 Sep 31;8(9):4275-4293. Epub 2017 Aug 31.
    Tianjin Key Laboratory of Biomedical Detecting Techniques and Instruments, Tianjin, 300072, China.
    Image reconstruction in the most model-based biophotonic imaging modalities essentially poses an ill-posed nonlinear inverse problem, which has been effectively tackled in the diffusion-approximation-satisfied scenarios such as diffuse optical tomography. Nevertheless, a nonlinear implementation in high-resolution laminar optical tomography (LOT) is normally computationally-costly due to its strong dependency on a dense source-detector configuration and a physically-rigorous photon-transport model. To circumvent the adversity, we herein propose a practical nonlinear LOT approach to the absorption reconstruction. Read More

    Three-dimensional continuous max flow optimization-based serous retinal detachment segmentation in SD-OCT for central serous chorioretinopathy.
    Biomed Opt Express 2017 Sep 29;8(9):4257-4274. Epub 2017 Aug 29.
    School of Electronic and Electrical Engineering, Sungkyunkwan University, South Korea.
    Assessment of serous retinal detachment plays an important role in the diagnosis of central serous chorioretinopathy (CSC). In this paper, we propose an automatic, three-dimensional segmentation method to detect both neurosensory retinal detachment (NRD) and pigment epithelial detachment (PED) in spectral domain optical coherence tomography (SD-OCT) images. The proposed method involves constructing a probability map from training samples using random forest classification. Read More

    Quantification of collagen organization in histopathology samples using liquid crystal based polarization microscopy.
    Biomed Opt Express 2017 Sep 29;8(9):4243-4256. Epub 2017 Aug 29.
    Laboratory for Optical and Computational Instrumentation, University of Wisconsin at Madison, Madison WI, USA.
    A number of histopathology studies have utilized the label free microscopy method of Second Harmonic Generation (SHG) to investigate collagen organization in disease onset and progression. Here we explored an alternative label free imaging approach, LC-PolScope that is based on liquid crystal based polarized light imaging. We demonstrated that this more accessible technology has the ability to visualize all fibers of interest and has a good to excellent correlation between SHG and LC-PolScope measurements in fibrillar collagen orientation and alignment. Read More

    Hyperspectral imaging with laser-scanning sum-frequency generation microscopy.
    Biomed Opt Express 2017 Sep 29;8(9):4230-4242. Epub 2017 Aug 29.
    Department of Chemistry, University of California, Irvine, CA 92697, USA.
    Vibrationally sensitive sum-frequency generation (SFG) microscopy is a chemically selective imaging technique sensitive to non-centrosymmetric molecular arrangements in biological samples. The routine use of SFG microscopy has been hampered by the difficulty of integrating the required mid-infrared excitation light into a conventional, laser-scanning nonlinear optical (NLO) microscope. In this work, we describe minor modifications to a regular laser-scanning microscope to accommodate SFG microscopy as an imaging modality. Read More

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