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    2764 results match your criteria Biomedical optics express[Journal]

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    Multiscale nonlinear microscopy and widefield white light imaging enables rapid histological imaging of surgical specimen margins.
    Biomed Opt Express 2018 May 30;9(5):2457-2475. Epub 2018 Apr 30.
    Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science and Research Laboratory of Electronics, 32 Vassar Street, Cambridge, MA 02139,USA.
    The ability to histologically assess surgical specimens in real-time is a long-standing challenge in cancer surgery, including applications such as breast conserving therapy (BCT). Up to 40% of women treated with BCT for breast cancer require a repeat surgery due to postoperative histological findings of close or positive surgical margins using conventional formalin fixed paraffin embedded histology. Imaging technologies such as nonlinear microscopy (NLM), combined with exogenous fluorophores can rapidly provide virtual H&E imaging of surgical specimens without requiring microtome sectioning, facilitating intraoperative assessment of margin status. Read More

    Quantitative multispectral optical evaluation of human ovarian tissue using spatial frequency domain imaging.
    Biomed Opt Express 2018 May 30;9(5):2451-2456. Epub 2018 Apr 30.
    Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USA.
    About 85-90% of all ovarian cancers are carcinomas; these manifest clinically as mass-forming epithelial proliferations involving the ovary. In this study, a visible light spatial frequency domain imaging (SFDI) system was used for multispectral imaging and quantitative evaluation of freshly excised benign and malignant human ovarian tissues. A total of 14 ovaries from 11 patients undergoing oophorectomy were investigated. Read More

    Potential of short-wave infrared spectroscopy for quantitative depth profiling of stratum corneum lipids and water in dermatology.
    Biomed Opt Express 2018 May 27;9(5):2436-2450. Epub 2018 Apr 27.
    Department of Personal Care and Wellness, Philips Research, 5656AE, Eindhoven, The Netherlands.
    We demonstrate the feasibility of short wave infrared (SWIR) spectroscopy combined with tape stripping for depth profiling of lipids and water in the stratum corneum of human skin. The proposed spectroscopic technique relies on differential detection at three wavelengths of 1720, 1750, and 1770 nm, with varying ratio of the lipid-to-water absorption coefficient and an 'isosbestic point'. Comparison of the data acquired using SWIR spectroscopy with that obtained by a gold standard for non-invasive quantitative molecular-specific skin measurements, namely confocal Raman spectroscopy (CRS), revealed specificity of the proposed modality for water and lipid quantification. Read More

    3D + time blood flow mapping using SPIM-microPIV in the developing zebrafish heart.
    Biomed Opt Express 2018 May 27;9(5):2418-2435. Epub 2018 Apr 27.
    School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK.
    We present SPIM-μPIV as a flow imaging system, capable of measuring flow information with 3D micron-scale resolution. Our system was validated using a phantom experiment consisting of a flow of beads in a 50 μm diameter FEP tube. Then, with the help of optical gating techniques, we obtained 3D + time flow fields throughout the full heartbeat in a ∼3 day old zebrafish larva using fluorescent red blood cells as tracer particles. Read More

    Six-wave mixing coherent anti-Stokes Raman scattering microscopy.
    Biomed Opt Express 2018 May 27;9(5):2407-2417. Epub 2018 Apr 27.
    "Gleb Wataghin" Institute of Physics, University of Campinas (UNICAMP), 13.083-859 Campinas, SP, Brazil.
    Acquiring images of biological tissues and cells without the assistance of exogenous labels with a fast repetition rate and chemical specificity is what coherent anti-Stokes Raman Scattering (CARS) imaging offers. Nonresonant background (NRB) is one of the main drawbacks of the CARS microscopy technique because it limits the detection of weak Raman lines and the detection of low-concentration molecules. We show that a six-wave mixing process with two beams, which is a cascade effect of CARS, show better signal/NRB ratio and can be utilized for biological tissues imaging. Read More

    Enhancement of morphological and vascular features in OCT images using a modified Bayesian residual transform.
    Biomed Opt Express 2018 May 27;9(5):2394-2406. Epub 2018 Apr 27.
    Department of Physics and Astronomy, University of Waterloo, Ontario, N2L 3G1, Canada.
    A novel image processing algorithm based on a modified Bayesian residual transform (MBRT) was developed for the enhancement of morphological and vascular features in optical coherence tomography (OCT) and OCT angiography (OCTA) images. The MBRT algorithm decomposes the original OCT image into multiple residual images, where each image presents information at a unique scale. Scale selective residual adaptation is used subsequently to enhance morphological features of interest, such as blood vessels and tissue layers, and to suppress irrelevant image features such as noise and motion artefacts. Read More

    Intravital imaging of a pulmonary endothelial surface layer in a murine sepsis model.
    Biomed Opt Express 2018 May 26;9(5):2383-2393. Epub 2018 Apr 26.
    Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, South Korea.
    Direct intravital imaging of an endothelial surface layer (ESL) in pulmonary microcirculation could be a valuable approach to investigate the role of a vascular endothelial barrier in various pathological conditions. Despite its importance as a marker of endothelial cell damage and impairment of the vascular system, visualization of ESL has remained a challenging technical issue. In this work, we implemented a pulmonary microcirculation imaging system integrated to a custom-design video-rate laser scanning confocal microscopy platform. Read More

    Nth-order linear algorithm for diffuse correlation tomography.
    Biomed Opt Express 2018 May 26;9(5):2365-2382. Epub 2018 Apr 26.
    Shanxi Provincial Key Laboratory for Biomedical Imaging and Big Data, North University of China, No. 3 Xueyuan Road, Taiyuan 030051, China.
    The current approaches to imaging the tissue blood flow index (BFI) from diffuse correlation tomography (DCT) data are either an analytical solution or a finite element method, both of which are unable to simultaneously account for the tissue heterogeneity and fully utilize the DCT data. In this study, a new imaging concept for DCT, namely NL-DCT, was created by us in which the medical images are combined with light Monte Carlo simulation to provide geometrical and heterogeneous information in tissue. Moreover, the DCT data at multiple delay time are fully utilized via iterative linear regression. Read More

    Assessing blood vessel perfusion and vital signs through retinal imaging photoplethysmography.
    Biomed Opt Express 2018 May 26;9(5):2351-2364. Epub 2018 Apr 26.
    Photonics Engineering and Health Technology Research Group, Wolfson School of Mechanical, Electrical and Manufacturing Engineering, Loughborough University, Loughborough, Leicestershire, LE11 3TU, UK.
    One solution to the global challenge of increasing ocular disease is a cost-effective technique for rapid screening and assessment. Current ophthalmic imaging techniques, e.g. Read More

    Effective bidirectional scanning pattern for optical coherence tomography angiography.
    Biomed Opt Express 2018 May 25;9(5):2336-2350. Epub 2018 Apr 25.
    Simon Fraser University, Department of Engineering Science, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada.
    We demonstrate the utility of a novel scanning method for optical coherence tomography angiography (OCTA). Although raster scanning is commonly used for OCTA imaging, a bidirectional approach would lessen the distortion caused by galvanometer-based scanners as sources continue to increase sweep rates. As shown, a unidirectional raster scan approach has a lower effective scanning time than bidirectional approaches; however, a strictly bidirectional approach causes contrast variation along the B-scan direction due to the non-uniform time interval between B-scans. Read More

    Compact fiber-based multi-photon endoscope working at 1700 nm.
    Biomed Opt Express 2018 May 25;9(5):2326-2335. Epub 2018 Apr 25.
    College of Optical Sciences, University of Arizona, Tucson, AZ 85721, USA.
    We present the design, implementation and performance analysis of a compact multi-photon endoscope based on a piezo electric scanning tube. A miniature objective lens with a long working distance and a high numerical aperture (≈ 0.5) is designed to provide a diffraction limited spot size. Read More

    Spatial and temporal identification of cerebral infarctions based on multiphoton microscopic imaging.
    Biomed Opt Express 2018 May 24;9(5):2312-2325. Epub 2018 Apr 24.
    Key Laboratory of OptoElectronic Science and Technology for Medicine of Ministry of Education, Fujian Provincial Key Laboratory of Photonics Technology, Fujian Normal University, Fuzhou 350007, China.
    Ischemic stroke is a leading cause of death and permanent disability worldwide. Middle cerebral artery occlusion (MCAO) of variable duration times could be anticipated to result in varying degrees of injury that evolve spatially over time. Therefore, investigations following strokes require information concerning the spatiotemporal dimensions of the ischemic core as well as of perilesional areas. Read More

    Fiber-based tunable repetition rate source for deep tissue two-photon fluorescence microscopy.
    Biomed Opt Express 2018 May 23;9(5):2304-2311. Epub 2018 Apr 23.
    School of Applied Physics and Engineering, Cornell University, Ithaca, NY 14850, USA.
    Deep tissue multiphoton imaging requires high peak power to enhance signal and low average power to prevent thermal damage. Both goals can be advantageously achieved through laser repetition rate tuning instead of simply adjusting the average power. We show that the ideal repetition rate for deep two-photon imaging in the mouse brain is between 1 and 10 MHz, and we present a fiber-based source with an arbitrarily tunable repetition rate within this range. Read More

    Intra-class variability in diffuse reflectance spectroscopy: application to porcine adipose tissue.
    Biomed Opt Express 2018 May 20;9(5):2297-2303. Epub 2018 Apr 20.
    Applied Optical Techniques Group, TEISA Department, University of Cantabria, Av. de los Castros s/n, 39005, Santander, Spain.
    Optical diffuse reflectance spectroscopy (DRS) has great potential in the study, diagnosis, and discrimination of biological tissues. Discrimination is based on massive measurements that conform training sets. These sets are then used to classify tissues according to the biomedical application. Read More

    5-ALA fluorescence and laser Doppler flowmetry for guidance in a stereotactic brain tumor biopsy.
    Biomed Opt Express 2018 May 20;9(5):2284-2296. Epub 2018 Apr 20.
    Department of Biomedical Engineering, Linköping University, Sweden.
    A fiber optic probe was developed for guidance during stereotactic brain biopsy procedures to target tumor tissue and reduce the risk of hemorrhage. The probe was connected to a setup for the measurement of 5-aminolevulinic acid (5-ALA) induced fluorescence and microvascular blood flow. Along three stereotactic trajectories, fluorescence (n = 109) and laser Doppler flowmetry (LDF) (n = 144) measurements were done in millimeter increments. Read More

    Analysis of dermal composite conditions using collagen absorption characteristics in the THz range.
    Biomed Opt Express 2018 May 20;9(5):2277-2283. Epub 2018 Apr 20.
    National Institute of Information and Communications Technology, Koganei, Tokyo 184-8795, Japan.
    The absorption characteristics of the dermis were reviewed in the terahertz range from 0.2 to 2 THz. The absorption magnitude of the dermis was higher than that of the epidermis model owing to the inclusion of collagen fibers. Read More

    Terahertz time-domain spectroscopy for non-invasive assessment of water content in biological samples.
    Biomed Opt Express 2018 May 20;9(5):2266-2276. Epub 2018 Apr 20.
    THz Biomedicine Laboratory, ITMO University, 3 b Kadetskaya Line, St. Petersburg, 197101, Russia.
    We apply terahertz time-domain spectroscopy for the quantitative non-invasive assessment of the water content in biological samples, such as tree leaves and pork muscles. The developed experimental terahertz time-domain spectroscopy system operates both in transmission and reflection modes. The Landau-Looyenga-Lifshitz-based model is used for the calculation of the water concentration within the samples. Read More

    The value of ultrahigh resolution OCT in dermatology - delineating the dermo-epidermal junction, capillaries in the dermal papillae and vellus hairs.
    Biomed Opt Express 2018 May 19;9(5):2240-2265. Epub 2018 Apr 19.
    Technical University of Denmark, DTU Fotonik, Kongens Lyngby, 2800, Denmark.
    Optical coherence tomography (OCT) imaging of the skin is gaining recognition and is increasingly applied to dermatological research. A key dermatological parameter inferred from an OCT image is the epidermal (Ep) thickness as a thickened Ep can be an indicator of a skin disease. Agreement in the literature on the signal characters of Ep and the subjacent skin layer, the dermis (D), is evident. Read More

    Performance of optoacoustic and fluorescence imaging in detecting deep-seated fluorescent agents.
    Biomed Opt Express 2018 May 19;9(5):2229-2239. Epub 2018 Apr 19.
    Institute for Biological and Medical Imaging (IBMI), Helmholtz Center Munich, Ingolstädter Landstr. 1, 85764 Neuherberg, Germany.
    Fluorescent contrast agents are widely employed in biomedical research. While many studies have reported deep tissue imaging of fluorescent moieties using either fluorescence-based or absorption-based (optoacoustic) imaging systems, no systematic comparison has been performed regarding the actual performance of these imaging modalities in detecting deep-seated fluorescent agents. Herein, an integrated imager combining epi-fluorescence and volumetric optoacoustic imaging capabilities has been employed in order to evaluate image degradation with depth for several commonly-used near-infrared dyes in both modes. Read More

    Biodynamic digital holography of chemoresistance in a pre-clinical trial of canine B-cell lymphoma.
    Biomed Opt Express 2018 May 17;9(5):2214-2228. Epub 2018 Apr 17.
    Department of Physics and Astronomy, Purdue University, 525 Northwestern Ave, West Lafayette, IN 47907, USA.
    Biodynamic digital holography was used to obtain phenotypic profiles of canine non-Hodgkin B-cell lymphoma biopsies treated with standard-of-care chemotherapy. Biodynamic signatures from the living 3D tissues were extracted using fluctuation spectroscopy from intracellular Doppler light scattering in response to the molecular mechanisms of action of therapeutic drugs that modify a range of internal cellular motions. The standard-of-care to treat B-cell lymphoma in both humans and dogs is a combination CHOP therapy that consists of doxorubicin, prednisolone, cyclophosphamide and vincristine. Read More

    A handheld microscope integrating photoacoustic microscopy and optical coherence tomography.
    Biomed Opt Express 2018 May 16;9(5):2205-2213. Epub 2018 Apr 16.
    Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, 518055, China.
    The combination of optical resolution photoacoustic microscopy (ORPAM) and optical coherence tomography (OCT) is capable of providing complementary imaging contrasts. Unfortunately, the miniaturization of ORPAM remains a major challenge in the development of a handheld dual-modality imaging microscope with OCT. Here, we report the design and evaluation of an integrated ORPAM and OCT imaging probe using a two-dimensional MEMS (micro-electro-mechanical-system)-based optical scanner. Read More

    Optimization of wavelength selection for multispectral image acquisition: a case study of atrial ablation lesions.
    Biomed Opt Express 2018 May 16;9(5):2189-2204. Epub 2018 Apr 16.
    Department of Pharmacology & Physiology, The George Washington University Medical Center, 2300 Eye Street NW, Washington, DC 20037, USA.
    In vivo autofluorescence hyperspectral imaging of moving objects can be challenging due to motion artifacts and to the limited amount of acquired photons. To address both limitations, we selectively reduced the number of spectral bands while maintaining accurate target identification. Several downsampling approaches were applied to data obtained from the atrial tissue of adult pigs with sites of radiofrequency ablation lesions. Read More

    Non-invasive quantification of the developing optical properties and graded index of the embryonic eye lens using SPIM.
    Biomed Opt Express 2018 May 10;9(5):2176-2188. Epub 2018 Apr 10.
    Department of Physics, Durham University, South Road, Durham, DH1 3LE, UK.
    Graded refractive index lenses are inherent to advanced visual systems in animals. By understanding their formation and local optical properties, significant potential for improved ocular healthcare may be realized. We report a novel technique measuring the developing optical power of the eye lens, in a living animal, by exploiting the orthogonal imaging modality of a selective plane illumination microscope (SPIM). Read More

    Dielectric barrier discharge plasma treatment of modified SU-8 for biosensing applications.
    Biomed Opt Express 2018 May 9;9(5):2168-2175. Epub 2018 Apr 9.
    School of Electrical and Computer Engineering, University of Campinas, 13083-852 Campinas, SP, Brazil.
    In this work we demonstrate the use of a dielectric barrier discharge plasma for the treatment of SU-8. The resulting hydrophilic surface displays a 5° contact angle and (0.40 ± 0. Read More

    Fast volume-scanning light sheet microscopy reveals transient neuronal events.
    Biomed Opt Express 2018 May 9;9(5):2154-2167. Epub 2018 Apr 9.
    Department of Pharmacology, University of Oxford, Oxford, OX1 3QT, UK.
    Light sheet fluorescence microscopy offers considerable potential to the cellular neuroscience community as it makes it possible to image extensive areas of neuronal structures, such as axons or dendrites, with a low light budget, thereby minimizing phototoxicity. However, the shallow depth of a light sheet, which is critical for achieving high contrast, well resolved images, adds a significant challenge if fast functional imaging is also required, as multiple images need to be collected across several image planes. Consequently, fast functional imaging of neurons is typically restricted to a small tissue volume where part of the neuronal structure lies within the plane of a single image. Read More

    Glioblastoma cells labeled by robust Raman tags for enhancing imaging contrast.
    Biomed Opt Express 2018 May 9;9(5):2142-2153. Epub 2018 Apr 9.
    Department of Photonics, National Cheng Kung University, Tainan, 70101, Taiwan.
    Complete removal of a glioblastoma multiforme (GBM), a highly malignant brain tumor, is challenging due to its infiltrative characteristics. Therefore, utilizing imaging agents such as fluorophores to increase the contrast between GBM and normal cells can help neurosurgeons to locate residual cancer cells during image guided surgery. In this work, Raman tag based labeling and imaging for GBM cells in vitro is described and evaluated. Read More

    High-throughput intensity diffraction tomography with a computational microscope.
    Biomed Opt Express 2018 May 5;9(5):2130-2141. Epub 2018 Apr 5.
    Department of Electrical and Computer Engineering, Boston University, Boston, MA 02215, USA.
    We demonstrate a motion-free intensity diffraction tomography technique that enables the direct inversion of 3D phase and absorption from intensity-only measurements for weakly scattering samples. We derive a novel linear forward model featuring slice-wise phase and absorption transfer functions using angled illumination. This new framework facilitates flexible and efficient data acquisition, enabling arbitrary sampling of the illumination angles. Read More

    White light polarization sensitive optical coherence tomography for sub-micron axial resolution and spectroscopic contrast in the murine retina.
    Biomed Opt Express 2018 May 5;9(5):2115-2129. Epub 2018 Apr 5.
    Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20/4L, 1090 Vienna, Austria.
    A white light polarization sensitive optical coherence tomography system has been developed, using a supercontinuum laser as the light source. By detecting backscattered light from 400 - 700 nm, an axial resolution of 1.0 µm in air was achieved. Read More

    Circumferential-scanning endoscopic optical coherence tomography probe based on a circular array of six 2-axis MEMS mirrors.
    Biomed Opt Express 2018 May 5;9(5):2104-2114. Epub 2018 Apr 5.
    University of Florida, Gainesville, FL, 26110-613, USA.
    We present a novel circumferential-scan endoscopic optical coherence tomography (OCT) probe by using a circular array of six electrothermal microelectromechanical (MEMS) mirrors and six C-lenses. The MEMS mirrors have a 0.5 mm × 0. Read More

    Selective delivery of laser energy to ester bonds of triacylglycerol in lipid droplets of adipocyte using a quantum cascade laser.
    Biomed Opt Express 2018 May 4;9(5):2095-2103. Epub 2018 Apr 4.
    Department of Medical Spectroscopy, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-Ku, Hamamatsu, Shizuoka 431-3192, Japan.
    The recent development of quantum cascade lasers (QCLs) has facilitated the irradiation of a mid-infrared laser beam that is specifically absorbed by a target molecular bond. Aiming for a selective delivery of laser energy to a specific absorption at 1,738 cm by the ester bonds of triacylglycerol (TAG), a QCL beam with a wavenumber of 1,710 cm was irradiated to 3T3-L1 adipocytes and preadipocytes. Neutral red staining, and FITC-labeled annexin V and ethidium homodimer-III assays revealed the occurrence of adipocyte-specific cell death 24 h after QCL irradiation. Read More

    Quantitative characterization of turbidity by radiative transfer based reflectance imaging.
    Biomed Opt Express 2018 May 4;9(5):2081-2094. Epub 2018 Apr 4.
    Institute for Advanced Optics, Hunan Institute of Science and Technology, Yueyang, Hunan 414006, China.
    A new and noncontact approach of multispectral reflectance imaging has been developed to inversely determine the absorption coefficient of μ , the scattering coefficient of μ and the anisotropy factor g of a turbid target from one measured reflectance image. The incident beam was profiled with a diffuse reflectance standard for deriving both measured and calculated reflectance images. A GPU implemented Monte Carlo code was developed to determine the parameters with a conjugate gradient descent algorithm and the existence of unique solutions was shown. Read More

    Liquid phantoms for near-infrared and diffuse correlation spectroscopies with tunable optical and dynamic properties.
    Biomed Opt Express 2018 May 4;9(5):2068-2080. Epub 2018 Apr 4.
    ICFO-Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels (Barcelona), Spain.
    We present the recipe and characterization for preparing liquid phantoms that are suitable for both near-infrared spectroscopy and diffuse correlation spectroscopy. The phantoms have well-defined and tunable optical and dynamic properties, and consist of a solution of water and glycerol with fat emulsion as the scattering element. The recipe takes into account the effect of bulk refractive index changes due to the addition of glycerol, which is commonly used to alter the sample viscosity. Read More

    Automated spectroscopic retinal oximetry with visible-light optical coherence tomography.
    Biomed Opt Express 2018 May 4;9(5):2056-2067. Epub 2018 Apr 4.
    Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA.
    Accurate, quantitative assessment of retinal blood oxygen saturation ( ) may provide a useful early indicator of pathophysiology in several ocular diseases. Here, with visible-light optical coherence tomography (OCT), we demonstrate an automated spectroscopic retinal oximetry algorithm to measure the within the retinal arteries (A- ) and veins (V- ) in rats by automatically detecting the vascular posterior boundary on cross-sectional structural OCT. The algorithm was validated with flow phantoms and in rats by comparing the results, respectively, to those obtained using a blood gas analyzer and pulse oximetry. Read More

    Analysis of hepatitis C infection using Raman spectroscopy and proximity based classification in the transformed domain.
    Biomed Opt Express 2018 May 3;9(5):2041-2055. Epub 2018 Apr 3.
    Pattern Recognition Lab, Pakistan Institute of Engineering and Applied Sciences (PIEAS), Nilore, Islamabad, 45650, Pakistan.
    This work presents a diagnostic system for the hepatitis C infection using Raman spectroscopy and proximity based classification. The proposed method exploits transformed Raman spectra using the proximity based machine learning technique and is denoted as RS-PCA-Prox. First, Raman spectral data is baseline corrected by subtracting noise and low intensity background. Read More

    Blood vessel detection, localization and estimation using a smart laparoscopic grasper: a Monte Carlo study.
    Biomed Opt Express 2018 May 3;9(5):2027-2040. Epub 2018 Apr 3.
    Briteseed, 4660 N. Ravenswood Ave Chicago, IL 60640, USA.
    For centuries, surgeons have relied on their sense of touch to identify vital structures such as blood vessels in traditional open surgery. Over the past two decades, surgeons have shifted to minimally invasive surgical (MIS) approaches, including laparoscopic surgery, which include benefits such as less scarring, less risk for infection, and quicker recovery times. In fact, some surgeries such as cholecystectomies have seen more than an 80% adoption of this technique because of those benefits. Read More

    Fast localization method of an anomaly in tissue based on differential optical density.
    Biomed Opt Express 2018 May 2;9(5):2018-2026. Epub 2018 Apr 2.
    School of Electronics and Information Engineering, Tianjin Polytechnic University, Tianjin 300387, China.
    The position of the source-detector (S-D) relative to an anomaly has an important influence on the detection effect in non-invasive near-infrared spectroscopy-based methods. In this study, a single-source multi-detector structure was designed in order to realize the rapid localization of anomalies within tissue. This method uses finite element analysis of the optical density distribution for different horizontal positions, depths and diameters of anomalies. Read More

    Sub-clinical assessment of atopic dermatitis severity using angiographic optical coherence tomography.
    Biomed Opt Express 2018 Apr 29;9(4):2001-2017. Epub 2018 Mar 29.
    Department of Electronic and Electrical Engineering, University of Sheffield, Sheffield, UK.
    Measurement of sub-clinical atopic dermatitis (AD) is important for determining how long therapies should be continued after clinical clearance of visible AD lesions. An important biomarker of sub-clinical AD is epidermal hypertrophy, the structural measures of which often make optical coherence tomography (OCT) challenging due to the lack of a clearly delineated dermal-epidermal junction in AD patients. Alternatively, angiographic OCT measurements of vascular depth and morphology may represent a robust biomarker for quantifying the severity of clinical and sub-clinical AD. Read More

    Rapid volumetric imaging with Bessel-Beam three-photon microscopy.
    Biomed Opt Express 2018 Apr 29;9(4):1992-2000. Epub 2018 Mar 29.
    State Key Laboratory of Advanced Optical Communication System and Networks, School of Electronics Engineering and Computer Science, Peking University, Beijing 100871, China.
    Owing to its tissue-penetration ability, multi-photon fluorescence microscopy allows for the high-resolution, non-invasive imaging of deep tissue ; the recently developed three-photon microscopy (3PM) has extended the depth of high-resolution, non-invasive functional imaging of mouse brains to beyond 1.0 mm. However, the low repetition rate of femtosecond lasers that are normally used in 3PM limits the temporal resolution of point-scanning three-photon microscopy. Read More

    Distinguishing between whole cells and cell debris using surface plasmon coupled emission.
    Biomed Opt Express 2018 Apr 29;9(4):1977-1991. Epub 2018 Mar 29.
    Center for Advanced Sensor Technology, University of Maryland, Baltimore County, MD 21227, USA.
    Distinguishing between whole cells and cell debris is important in microscopy, e.g., in screening of pulmonary patients for infectious tuberculosis. Read More

    50 Hz volumetric functional imaging with continuously adjustable depth of focus.
    Biomed Opt Express 2018 Apr 28;9(4):1964-1976. Epub 2018 Mar 28.
    Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA.
    Understanding how neural circuits control behavior requires monitoring a large population of neurons with high spatial resolution and volume rate. Here we report an axicon-based Bessel beam module with continuously adjustable depth of focus (CADoF), that turns frame rate into volume rate by extending the excitation focus in the axial direction while maintaining high lateral resolutions. Cost-effective and compact, this CADoF Bessel module can be easily integrated into existing two-photon fluorescence microscopes. Read More

    Efficiency of ocular UV protection by clear lenses.
    Biomed Opt Express 2018 Apr 27;9(4):1948-1963. Epub 2018 Mar 27.
    Carl Zeiss Vision International GmbH, Aalen, Germany.
    Ocular UV doses accumulate all-day, not only during periods of direct sun exposure. The UV protection efficiency of three clear lenses was evaluated experimentally, validated by simulation, and compared to non-UV protection: a first spectacle lens with a tailored UV absorber, a second spectacle lens, minimizing UV back reflections, as well as a third spectacle lens, combining both. A tailored UV-absorber efficiently reduced overall UV irradiance to 7 %, whereas reduction of back-reflections still left UV irradiance at 42 %. Read More

    Multispectral analog-mean-delay fluorescence lifetime imaging combined with optical coherence tomography.
    Biomed Opt Express 2018 Apr 27;9(4):1930-1947. Epub 2018 Mar 27.
    Department of Biomedical Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04673, South Korea.
    The pathophysiological progression of chronic diseases, including atherosclerosis and cancer, is closely related to compositional changes in biological tissues containing endogenous fluorophores such as collagen, elastin, and NADH, which exhibit strong autofluorescence under ultraviolet excitation. Fluorescence lifetime imaging (FLIm) provides robust detection of the compositional changes by measuring fluorescence lifetime, which is an inherent property of a fluorophore. In this paper, we present a dual-modality system combining a multispectral analog-mean-delay (AMD) FLIm and a high-speed swept-source optical coherence tomography (OCT) to simultaneously visualize the cross-sectional morphology and biochemical compositional information of a biological tissue. Read More

    Decreased resting-state brain signal complexity in patients with mild cognitive impairment and Alzheimer's disease: a multiscale entropy analysis.
    Biomed Opt Express 2018 Apr 26;9(4):1916-1929. Epub 2018 Mar 26.
    Department of Neurology, XuanWu Hospital of Capital Medical University, Beijing, 100053, China.
    Multiscale entropy (MSE) analysis is a novel entropy-based analysis method for quantifying the complexity of dynamic neural signals and physiological systems across multiple temporal scales. This approach may assist in elucidating the pathophysiologic mechanisms of amnestic mild cognitive impairment (aMCI) and Alzheimer's disease (AD). Using resting-state fNIRS imaging, we recorded spontaneous brain activity from 31 healthy controls (HC), 27 patients with aMCI, and 24 patients with AD. Read More

    Smartphone confocal microscopy for imaging cellular structures in human skin .
    Biomed Opt Express 2018 Apr 26;9(4):1906-1915. Epub 2018 Mar 26.
    Wellman Center for Photomedicine, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA.
    We report development of a low-cost smartphone confocal microscope and its first demonstration of human skin imaging. The smartphone confocal microscope uses a slit aperture and diffraction grating to conduct two-dimensional confocal imaging without using any beam scanning devices. Lateral and axial resolutions of the smartphone confocal microscope were measured as 2 and 5 µm, respectively. Read More

    Observation of laser-induced elastic waves in agar skin phantoms using a high-speed camera and a laser-beam-deflection probe.
    Biomed Opt Express 2018 Apr 26;9(4):1893-1905. Epub 2018 Mar 26.
    Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva cesta 6, 1000 Ljubljana, Slovenia.
    We present an optical study of elastic wave propagation inside skin phantoms consisting of agar gel as induced by an Er:YAG (wavelength of 2.94 μm) laser pulse. A laser-beam-deflection probe is used to measure ultrasonic propagation and a high-speed camera is used to record displacements in ablation-induced elastic transients. Read More

    Compact akinetic swept source optical coherence tomography angiography at 1060 nm supporting a wide field of view and adaptive optics imaging modes of the posterior eye.
    Biomed Opt Express 2018 Apr 26;9(4):1871-1892. Epub 2018 Mar 26.
    Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.
    Imaging of the human retina with high resolution is an essential step towards improved diagnosis and treatment control. In this paper, we introduce a compact, clinically user-friendly instrument based on swept source optical coherence tomography (SS-OCT). A key feature of the system is the realization of two different operation modes. Read More

    Investigation of the influence of sampling schemes on quantitative dynamic fluorescence imaging.
    Biomed Opt Express 2018 Apr 26;9(4):1859-1870. Epub 2018 Mar 26.
    Engineering Research Center of Molecular and Neuro Imaging of Ministry of Education & School of Life Science and Technology, Xidian University, Xi'an, Shaanxi 710071, China.
    Dynamic optical data from a series of sampling intervals can be used for quantitative analysis to obtain meaningful kinetic parameters of probe . The sampling schemes may affect the quantification results of dynamic fluorescence imaging. Here, we investigate the influence of different sampling schemes on the quantification of binding potential () with theoretically simulated and experimentally measured data. Read More

    Differentiation of seborrheic keratosis from basal cell carcinoma, nevi and melanoma by RGB autofluorescence imaging.
    Biomed Opt Express 2018 Apr 23;9(4):1852-1858. Epub 2018 Mar 23.
    Institute of Atomic Physics and Spectroscopy, University of Latvia, Raina Blvd. 19, Riga LV-1586, Latvia.
    A clinical trial on the autofluorescence imaging of skin lesions comprising 16 dermatologically confirmed pigmented nevi, 15 seborrheic keratosis, 2 dysplastic nevi, histologically confirmed 17 basal cell carcinomas and 1 melanoma was performed. The autofluorescence spatial properties of the skin lesions were acquired by smartphone RGB camera under 405 nm LED excitation. The diagnostic criterion is based on the calculation of the mean autofluorescence intensity of the examined lesion in the spectral range of 515 nm-700 nm. Read More

    Fiber-bundle-basis sparse reconstruction for high resolution wide-field microendoscopy.
    Biomed Opt Express 2018 Apr 23;9(4):1843-1851. Epub 2018 Mar 23.
    Light-Matter Interactions Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Japan.
    In order to observe deep regions of the brain, we propose the use of a fiber bundle for microendoscopy. Fiber bundles allow for the excitation and collection of fluorescence as well as wide field imaging while remaining largely impervious to image distortions brought on by bending. Furthermore, their thin diameter, from 200-500 m, means their impact on living tissue, though not absent, is minimal. Read More

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