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    2577 results match your criteria Biomedical optics express[Journal]

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    Two-photon microscopy imaging of oxidative stress in human living erythrocytes.
    Biomed Opt Express 2017 Dec 30;8(12):5834-5846. Epub 2017 Nov 30.
    Institute of Molecular Biology of National Academy of Sciences of Republic of Armenia, 7 Hasratyan str., 0014, Yerevan, Armenia.
    Red blood cells (RBCs) are known to be the most suitable cells to study oxidative stress, which is implicated in the etiopathology of many human diseases. The goal of the current study was to develop a new effective approach for assessing oxidative stress in human living RBCs using two-photon microscopy. To mimic oxidative stress in human living RBCs, an in vitro model was generated followed by two-photon microscopy imaging. Read More

    Periodic microstructures of blood capillaries revealed by synchrotron X-ray multi-resolution microscopic analysis.
    Biomed Opt Express 2017 Dec 30;8(12):5825-5833. Epub 2017 Nov 30.
    School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China.
    Cardiovascular diseases are closely related to structural blood capillaries lesions. Herein, microscopic investigations of mouse blood capillaries were performed at multiple spatial resolution by using synchrotron X-ray in-line phase contrast tomography and scanning transmission X-ray microscopy (STXM). The chemically fixed blood capillaries without any contrast agents were selected. Read More

    Intracerebral haemorrhage-induced injury progression assessed by cross-sectional photoacoustic tomography.
    Biomed Opt Express 2017 Dec 29;8(12):5814-5824. Epub 2017 Nov 29.
    School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu, China.
    In this study, we in vivo examined injury progression after intracerebral haemorrhage (ICH) induced by collagenase in mice using cross-sectional photoacoustic tomography (csPAT). csPAT displayed high resolution with high sensitivity for ICH detection. The PAT images obtained showed high correlation with conventional histologic images. Read More

    Ultrawidefield microscope for high-speed fluorescence imaging and targeted optogenetic stimulation.
    Biomed Opt Express 2017 Dec 29;8(12):5794-5813. Epub 2017 Nov 29.
    Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford St, Cambridge, MA 02138, USA.
    The rapid increase in the number and quality of fluorescent reporters and optogenetic actuators has yielded a powerful set of tools for recording and controlling cellular state and function. To achieve the full benefit of these tools requires improved optical systems with high light collection efficiency, high spatial and temporal resolution, and patterned optical stimulation, in a wide field of view (FOV). Here we describe our 'Firefly' microscope, which achieves these goals in a Ø6 mm FOV. Read More

    Structured illumination microscopy for dual-modality 3D sub-diffraction resolution fluorescence and refractive-index reconstruction.
    Biomed Opt Express 2017 Dec 28;8(12):5776-5793. Epub 2017 Nov 28.
    Department of Biomedical Engineering, Fitzpatrick Institute for Photonics, 1427 FCIEMAS, 101 Science Drive Box 90281, Durham, North Carolina 27708, USA.
    Though structured illumination (SI) microscopy is a popular imaging technique conventionally associated with fluorescent super-resolution, recent works have suggested its applicability towards sub-diffraction resolution coherent imaging with quantitative endogenous biological contrast. Here, we demonstrate that SI can efficiently integrate together the principles of fluorescent super-resolution and coherent synthetic aperture to achieve 3D dual-modality sub-diffraction resolution, fluorescence and refractive-index (RI) visualizations of biological samples. We experimentally demonstrate this framework by introducing a SI microscope capable of 3D sub-diffraction resolution fluorescence and RI imaging, and verify its biological visualization capabilities by experimentally reconstructing 3D RI/fluorescence visualizations of fluorescent calibration microspheres as well as alveolar basal epithelial adenocarcinoma (A549) and human colorectal adenocarcinmoa (HT-29) cells, fluorescently stained for F-actin. Read More

    High axial resolution imaging system for large volume tissues using combination of inclined selective plane illumination and mechanical sectioning.
    Biomed Opt Express 2017 Dec 27;8(12):5767-5775. Epub 2017 Nov 27.
    Collaborative Innovation Center for Biomedical Engineering, Wuhan National Laboratory for Optoelectronics-Huazhong University of Science and Technology, Wuhan, Hubei 430074, China.
    To resolve fine structures of biological systems like neurons, it is required to realize microscopic imaging with sufficient spatial resolution in three dimensional systems. With regular optical imaging systems, high lateral resolution is accessible while high axial resolution is hard to achieve in a large volume. We introduce an imaging system for high 3D resolution fluorescence imaging of large volume tissues. Read More

    Automated multimodal spectral histopathology for quantitative diagnosis of residual tumour during basal cell carcinoma surgery.
    Biomed Opt Express 2017 Dec 22;8(12):5749-5766. Epub 2017 Nov 22.
    School of Physics and Astronomy, University Park, University of Nottingham, Nottingham, NG7 2RD, UK.
    Multimodal spectral histopathology (MSH), an optical technique combining tissue auto-fluorescence (AF) imaging and Raman micro-spectroscopy (RMS), was previously proposed for detection of residual basal cell carcinoma (BCC) at the surface of surgically-resected skin tissue. Here we report the development of a fully-automated prototype instrument based on MSH designed to be used in the clinic and operated by a non-specialist spectroscopy user. The algorithms for the AF image processing and Raman spectroscopy classification had been first optimised on a manually-operated laboratory instrument and then validated on the automated prototype using skin samples from independent patients. Read More

    Observation of live chromatin dynamics in cells via 3D localization microscopy using Tetrapod point spread functions.
    Biomed Opt Express 2017 Dec 21;8(12):5735-5748. Epub 2017 Nov 21.
    Department of Chemistry, Stanford University, 375 North-South Mall, Stanford, California 94305, USA.
    We report the observation of chromatin dynamics in living budding yeast (Saccharomyces cerevisiae) cells, in three-dimensions (3D). Using dual color localization microscopy and employing a Tetrapod point spread function, we analyze the spatio-temporal dynamics of two fluorescently labeled DNA loci surrounding the GAL locus. From the measured trajectories, we obtain different dynamical characteristics in terms of inter-loci distance and temporal variance; when the GAL locus is activated, the 3D inter-loci distance and temporal variance increase compared to the inactive state. Read More

    Gabor optical coherence tomographic angiography (GOCTA) (Part I): human retinal imaging in vivo.
    Biomed Opt Express 2017 Dec 20;8(12):5724-5734. Epub 2017 Nov 20.
    Biophotonics and Bioengineering Lab, Department of Electrical and Computer Engineering, Ryerson University, Toronto, Ontario, Canada.
    Recently, parallel high A-line speed and wide field imaging for optical coherence tomography angiography (OCTA) has become more prevalent, resulting in a dramatic increase of data quantity which poses a challenge for real time imaging even for GPU in data processing. In this manuscript, we propose a new OCTA processing technique, Gabor optical coherence tomographic angiography (GOCTA), for label-free human retinal angiography imaging. In spectral domain optical coherence tomography (SDOCT), k-space resampling and Fourier transform (FFT) are required for the entire data set of interference fringes to calculate blood flow information in previous OCTA algorithms, which are computationally intensive. Read More

    Momentum transfer Monte Carlo for the simulation of laser speckle imaging and its application in the skin.
    Biomed Opt Express 2017 Dec 17;8(12):5708-5723. Epub 2017 Nov 17.
    Beckman Laser Institute, University of California-Irvine, 1002 Health Sciences Road East, Irvine, CA 92612, USA.
    Due to its simplicity and low cost, laser speckle imaging (LSI) has achieved widespread use in biomedical applications. However, interpretation of the blood-flow maps remains ambiguous, as LSI enables only limited visualization of vasculature below scattering layers such as the epidermis and skull. Here, we describe a computational model that enables flexible in-silico study of the impact of these factors on LSI measurements. Read More

    Augmented line-scan focal modulation microscopy for multi-dimensional imaging of zebrafish heart in vivo.
    Biomed Opt Express 2017 Dec 17;8(12):5698-5707. Epub 2017 Nov 17.
    Department of Biomedical Engineering, National University of Singapore, 117583, Singapore.
    Multi-dimensional fluorescence imaging of live animal models demands strong optical sectioning, high spatial resolution, fast image acquisition, and minimal photobleaching. While conventional laser scanning microscopes are capable of deep penetration and sub-cellular resolution, they are generally too slow and causing excessive photobleaching for volumetric or time-lapse imaging. We demonstrate the performance of an augmented line-scan focal modulation microscope (aLSFMM), a high-speed imaging platform that affords above video-rate imaging speed by the use of line scanning. Read More

    Correlative three-dimensional fluorescence and refractive index tomography: bridging the gap between molecular specificity and quantitative bioimaging.
    Biomed Opt Express 2017 Dec 17;8(12):5688-5697. Epub 2017 Nov 17.
    Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, South Korea.
    Optical diffraction tomography (ODT) provides label-free three-dimensional (3D) refractive index (RI) measurement of biological samples. However, due to the nature of the RI values of biological specimens, ODT has limited access to molecular specific information. Here, we present an optical setup combining ODT with three-channel 3D fluorescence microscopy, to enhance the molecular specificity of the 3D RI measurement. Read More

    Deblurring adaptive optics retinal images using deep convolutional neural networks.
    Biomed Opt Express 2017 Dec 16;8(12):5675-5687. Epub 2017 Nov 16.
    The Laboratory on Adaptive Optics, Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209, China.
    The adaptive optics (AO) can be used to compensate for ocular aberrations to achieve near diffraction limited high-resolution retinal images. However, many factors such as the limited aberration measurement and correction accuracy with AO, intraocular scatter, imaging noise and so on will degrade the quality of retinal images. Image post processing is an indispensable and economical method to make up for the limitation of AO retinal imaging procedure. Read More

    Spatial effect of conical angle on optical-thermal distribution for circumferential photocoagulation.
    Biomed Opt Express 2017 Dec 16;8(12):5663-5674. Epub 2017 Nov 16.
    Center for Marine-Integrated Biomedical Technology (BK21 Plus), Pukyong National University, Busan, South Korea.
    A uniformly diffusing applicator can be advantageous for laser treatment of tubular tissue. The current study investigated various conical angles for diffuser tips as a critical factor for achieving radially uniform light emission. A customized goniometer was employed to characterize the spatial uniformity of the light propagation. Read More

    High-throughput imaging of zebrafish embryos using a linear-CCD-based flow imaging system.
    Biomed Opt Express 2017 Dec 16;8(12):5651-5662. Epub 2017 Nov 16.
    Jiangsu Key Laboratory of Medical Optics, CAS Center for Excellence in Molecular Cell Science, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou 215163, China.
    High-throughput imaging and screening is essential for biomedical research and drug discovery using miniature model organisms such as zebrafish. This study introduces a high-speed imaging system which illuminates zebrafish embryos flowing through a capillary tube with a sheet of light and captures them using a linear charge-coupled device (CCD). This system can image dozens of zebrafish embryos per second. Read More

    Optical projection tomography for rapid whole mouse brain imaging.
    Biomed Opt Express 2017 Dec 15;8(12):5637-5650. Epub 2017 Nov 15.
    Laboratoire d'Optique Biomédicale, School of Engineering, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.
    In recent years, three-dimensional mesoscopic imaging has gained significant importance in life sciences for fundamental studies at the whole-organ level. In this manuscript, we present an optical projection tomography (OPT) method designed for imaging of the intact mouse brain. The system features an isotropic resolution of ~50 µm and an acquisition time of four to eight minutes, using a 3-day optimized clearing protocol. Read More

    Characterizing the optical properties of human brain tissue with high numerical aperture optical coherence tomography.
    Biomed Opt Express 2017 Dec 14;8(12):5617-5636. Epub 2017 Nov 14.
    Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital/Harvard Medical School, Charlestown, MA 02129, USA.
    Quantification of tissue optical properties with optical coherence tomography (OCT) has proven to be useful in evaluating structural characteristics and pathological changes. Previous studies primarily used an exponential model to analyze low numerical aperture (NA) OCT measurements and obtain the total attenuation coefficient for biological tissue. In this study, we develop a systematic method that includes the confocal parameter for modeling the depth profiles of high NA OCT, when the confocal parameter cannot be ignored. Read More

    Automated segmentation and quantification of OCT angiography for tracking angiogenesis progression.
    Biomed Opt Express 2017 Dec 14;8(12):5604-5616. Epub 2017 Nov 14.
    Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY 11794, USA.
    Angiogenesis is recognized as a crucial component of many neurovascular diseases such as stroke, carcinogenesis, and neurotoxicity of abused drug. The ability to track angiogenesis will facilitate a better understanding of disease progression and assessment of therapeutical effects. Optical coherence angiography (OCTA) is a promising tool to assess 3D microvascular networks due to its micron-level resolution, high sensitivity, and relatively large field of view. Read More

    Detection of optical activity with diode-integrated hyperbolic metasurfaces.
    Biomed Opt Express 2017 Dec 14;8(12):5594-5603. Epub 2017 Nov 14.
    Department of Electrical & Computer Engineering, University of California San Diego, La Jolla, CA, 92037, USA.
    We present an analytical technique for designing integrated polarized light-emitting diodes (LEDs) and polarization-sensitive photodiodes (PD) based on hyperbolic metasurfaces (HMS) for the detection of optical activity. Leveraging effective medium theory and the scattering matrix method, we first derive the conditions for optimizing the transmission efficiency of an LED-integrated HMS and the absorption efficiency of a PD-integrated HMS. We then propose using a differential detection technique with orthogonally oriented PD-integrated HMS to measure optical activity in an extremely compact volume. Read More

    Deformation velocity imaging using optical coherence tomography and its applications to the cornea.
    Biomed Opt Express 2017 Dec 13;8(12):5579-5593. Epub 2017 Nov 13.
    Department of Eye and Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, L7 8TX, UK.
    Optical coherence tomography (OCT) can monitor human donor corneas non-invasively during the de-swelling process following storage for corneal transplantation, but currently only resultant thickness as a function of time is extracted. To visualize and quantify the mechanism of de-swelling, we present a method exploiting the nanometer sensitivity of the Fourier phase in OCT data to image deformation velocities. The technique was demonstrated by non-invasively showing during de-swelling that osmotic flow through an intact epithelium is negligible and removing the endothelium approximately doubled the initial flow at that interface. Read More

    Multi-directional optical coherence tomography for retinal imaging.
    Biomed Opt Express 2017 Dec 13;8(12):5560-5578. Epub 2017 Nov 13.
    Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20 / 4L, 1090 Vienna, Austria.
    We introduce multi-directional optical coherence tomography (OCT), a technique for investigation of the scattering properties of directionally reflective tissue samples. By combining the concepts of multi-channel and directional OCT, this approach enables simultaneous acquisition of multiple reflectivity depth-scans probing a mutual sample location from differing angular orientations. The application of multi-directional OCT in retinal imaging allows for in-depth investigations on the directional reflectivity of the retinal nerve fiber layer, Henle's fiber layer and the photoreceptor layer. Read More

    Improved contrast in inverted selective plane illumination microscopy of thick tissues using confocal detection and structured illumination.
    Biomed Opt Express 2017 Dec 13;8(12):5546-5559. Epub 2017 Nov 13.
    Department of Biomedical Engineering, Tulane University, 500 Lindy Boggs Center, New Orleans, LA 70118, USA.
    Inverted selective plane illumination microscopy (iSPIM) enables fast, large field-of-view, long term imaging with compatibility with conventional sample mounting. However, the imaging quality can be deteriorated in thick tissues due to sample scattering. Three strategies have been adopted in this paper to optimize the imaging performance of iSPIM on thick tissue imaging: electronic confocal slit detection (eCSD), structured illumination (SI) and the two combined. Read More

    Three-dimensional side-view endomicroscope for tracking individual cells in vivo.
    Biomed Opt Express 2017 Dec 13;8(12):5533-5545. Epub 2017 Nov 13.
    Department of Internal Medicine, Division of Gastroenterology, University of Michigan, Ann Arbor, MI 48109, USA.
    We demonstrate a side-view endomicroscope using a monolithic 3-axis scanner placed in the post-objective position that performs either tilt or piston motion to achieve either optical scan angles >10° or large vertical displacements, respectively. This configuration allows for scaling down of instrument dimensions for high maneuverability and accurate positioning in vivo. Images exceeded either 700 × 600 μm2 in the horizontal plane or vertical depths of 200 μm. Read More

    Analytical models for time-domain diffuse correlation spectroscopy for multi-layer and heterogeneous turbid media.
    Biomed Opt Express 2017 Dec 9;8(12):5518-5532. Epub 2017 Nov 9.
    Department of Biomedical, Industrial and Human Factors Engineering, Wright State University, Dayton, OH 45435, USA.
    A novel approach for time-domain diffuse correlation spectroscopy (TD-DCS) has been recently proposed, which has the unique advantage by simultaneous measurements of optical and dynamical properties in a scattering medium. In this study, analytical models for calculating the time-resolved electric-field autocorrelation function is presented for a multi-layer turbid sample, as well as a semi-infinite medium embedded with a small dynamic heterogeneity. To verify the analytical models, we used Monte Carlo simulations, which demonstrated that the theoretical prediction for the time-resolved autocorrelation function was highly consistent with the Monte Carlo simulation, validating the proposed analytical models. Read More

    Fast label-free microscopy technique for 3D dynamic quantitative imaging of living cells.
    Biomed Opt Express 2017 Dec 9;8(12):5507-5517. Epub 2017 Nov 9.
    Universidad Complutense de Madrid, Facultad de Ciencias Físicas, Ciudad Universitaria s/n, Madrid 28040, Spain.
    The refractive index (RI) is an important optical characteristic that is often exploited in label-free microscopy for analysis of biological objects. A technique for 3D RI reconstruction of living cells has to be fast enough to capture the cell dynamics and preferably needs to be compatible with standard wide-field microscopes. To solve this challenging problem, we present a technique that provides fast measurement and processing of data required for real-time 3D visualization of the object RI. Read More

    Single shot, three-dimensional fluorescence microscopy with a spatially rotating point spread function.
    Biomed Opt Express 2017 Dec 9;8(12):5493-5506. Epub 2017 Nov 9.
    State Key Laboratory of Transient Optics and Photonics, Xi' an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi' an 710119, China.
    A wide-field fluorescence microscope with a double-helix point spread function (PSF) is constructed to obtain the specimen's three-dimensional distribution with a single snapshot. Spiral-phase-based computer-generated holograms (CGHs) are adopted to make the depth-of-field of the microscope adjustable. The impact of system aberrations on the double-helix PSF at high numerical aperture is analyzed to reveal the necessity of the aberration correction. Read More

    In vivo studies of transdermal nanoparticle delivery with microneedles using photoacoustic microscopy.
    Biomed Opt Express 2017 Dec 9;8(12):5483-5492. Epub 2017 Nov 9.
    School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, 637459, Singapore.
    Microneedle technology allows micron-sized conduits to be formed within the outermost skin layers for both localized and systemic delivery of therapeutics including nanoparticles. Histological methods are often employed for characterization, and unfortunately do not allow for the in vivo visualization of the delivery process. This study presents the utilization of optical resolution-photoacoustic microscopy to characterize the transdermal delivery of nanoparticles using microneedles. Read More

    In vivo real-time imaging of cutaneous hemoglobin concentration, oxygen saturation, scattering properties, melanin content, and epidermal thickness with visible spatially modulated light.
    Biomed Opt Express 2017 Dec 8;8(12):5468-5482. Epub 2017 Nov 8.
    Institute of Lasers and Biomedical Photonics, Biomedical Engineering College, Wenzhou Medical University, Wenzhou, Zhejiang, 325035, China.
    We present the real-time single snapshot multiple frequency demodulation - spatial frequency domain imaging (SSMD-SFDI) platform implemented with a visible digital mirror device that is capable of imaging and monitoring dynamic turbid medium and processes over a large field of view. One challenge in quantitative imaging of biological tissue such as the skin is the complex structure rendering techniques based on homogeneous medium models to fail. To address this difficulty we have also developed a novel method that maps the layered structure to a homogeneous medium for spatial frequency domain imaging. Read More

    Wavelet-based statistical classification of skin images acquired with reflectance confocal microscopy.
    Biomed Opt Express 2017 Dec 8;8(12):5450-5467. Epub 2017 Nov 8.
    University of Toulouse, IRIT-INPT, 2 rue Camichel, BP 7122, 31071 Toulouse cedex 7, France.
    Detecting skin lentigo in reflectance confocal microscopy images is an important and challenging problem. This imaging modality has not yet been widely investigated for this problem and there are a few automatic processing techniques. They are mostly based on machine learning approaches and rely on numerous classical image features that lead to high computational costs given the very large resolution of these images. Read More

    Two step imaging reconstruction using truncated pseudoinverse as a preliminary estimate in ultrasound guided diffuse optical tomography.
    Biomed Opt Express 2017 Dec 8;8(12):5437-5449. Epub 2017 Nov 8.
    Biomedical Engineering Department, Washington University in St. Louis, 1 Brookings Dr, St. Louis, MO 63130, USA.
    Due to the correlated nature of diffused light, the problem of reconstructing optical properties using diffuse optical tomography (DOT) is ill-posed. US-, MRI- or x-ray-guided DOT approaches can reduce the total number of parameters to be estimated and improve optical reconstruction accuracy. However, when the target volume is large, the number of parameters to estimate can exceed the number of measurements, resulting in an underdetermined imaging model. Read More

    Pencil-like imaging spectrometer for bio-samples sensing.
    Biomed Opt Express 2017 Dec 8;8(12):5427-5436. Epub 2017 Nov 8.
    State Key Laboratory of Modern Optical Instrumentations, Centre for Optical and Electromagnetic Research, Zhejiang University, Hangzhou, Zhejiang, 310058, China.
    Spectrally-resolved imaging techniques are becoming central to the investigation of bio-samples. In this paper, we demonstrate the use of a WIFI-camera as a detection module to assemble a pencil-like imaging spectrometer, which weighs only 140 g and has a size of 3.1 cm in diameter and 15. Read More

    Two-photon laser scanning microscopy with electrowetting-based prism scanning.
    Biomed Opt Express 2017 Dec 7;8(12):5412-5426. Epub 2017 Nov 7.
    Department of Mechanical Engineering, University of Colorado, Boulder, CO, 80309, USA.
    Laser scanners are an integral part of high resolution biomedical imaging systems such as confocal or 2-photon excitation (2PE) microscopes. In this work, we demonstrate the utility of electrowetting on dielectric (EWOD) prisms as a lateral laser-scanning element integrated in a conventional 2PE microscope. To the best of our knowledge, this is the first such demonstration for EWOD prisms. Read More

    Optical mapping of brain activation during the English to Chinese and Chinese to English sight translation.
    Biomed Opt Express 2017 Dec 7;8(12):5399-5411. Epub 2017 Nov 7.
    Bioimaging Core, Faculty of Health Sciences, University of Macau, Taipa, Macau SAR, China.
    Translating from Chinese into another language or vice versa is becoming a widespread phenomenon. However, current neuroimaging studies are insufficient to reveal the neural mechanism underlying translation asymmetry during Chinese/English sight translation. In this study, functional near infrared spectroscopy (fNIRS) was used to extract the brain activation patterns associated with Chinese/English sight translation. Read More

    Automated detection of photoreceptor disruption in mild diabetic retinopathy on volumetric optical coherence tomography.
    Biomed Opt Express 2017 Dec 7;8(12):5384-5398. Epub 2017 Nov 7.
    Casey Eye Institute, Oregon Health & Science University, Portland, OR, 97239, USA.
    Diabetic retinopathy is a pathology where microvascular circulation abnormalities ultimately result in photoreceptor disruption and, consequently, permanent loss of vision. Here, we developed a method that automatically detects photoreceptor disruption in mild diabetic retinopathy by mapping ellipsoid zone reflectance abnormalities from en face optical coherence tomography images. The algorithm uses a fuzzy c-means scheme with a redefined membership function to assign a defect severity level on each pixel and generate a probability map of defect category affiliation. Read More

    Correlative imaging of biological tissues with apertureless scanning near-field optical microscopy and confocal laser scanning microscopy.
    Biomed Opt Express 2017 Dec 7;8(12):5374-5383. Epub 2017 Nov 7.
    Center for Microscopy-Microanalysis and Information Processing, University Politehnica of Bucharest, Bucharest, 060042, Romania.
    Apertureless scanning near-field optical microscopy (ASNOM) has attracted considerable interest over the past years as a result of its valuable contrast mechanisms and capabilities for optical resolutions in the nanoscale range. However, at this moment the intersections between ASNOM and the realm of bioimaging are scarce, mainly due to data interpretation difficulties linked to the limited body of work performed so far in this field and hence the reduced volume of supporting information. We propose an imaging approach that holds significant potential for alleviating this issue, consisting of correlative imaging of biological specimens using a multimodal system that incorporates ASNOM and confocal laser scanning microscopy (CLSM), which allows placing near-field data into a well understood context of anatomical relevance. Read More

    Bridging medicine and biomedical technology: enhance translation of fundamental research to patient care.
    Biomed Opt Express 2017 Dec 3;8(12):5368-5373. Epub 2017 Nov 3.
    Wellman Center for Photomedicine, Massachusetts General Hospital Research Institute and Harvard Medical School, 40 Blossom Street, Boston, MA 02114, USA.
    The 'Bridging medicine and biomedical technology' special all-congress session took place for the first time at the OSA Biophotonics Congress: Optics in Life Sciences in 2017 (http://www.osa.org/enus/meetings/osa_meetings/optics_in_the_life_sciences/bridging_medicine_and_biomedical_technology_specia/). Read More

    Approach to breast cancer early detection via tracking of secondary speckle patterns reflected from the skin with artificial intradermal impurity.
    Biomed Opt Express 2017 Dec 2;8(12):5359-5367. Epub 2017 Nov 2.
    Faculty of Engineering and the Nanotechnology Center, Bar-Ilan University, Ramat-Gan 52900, Israel.
    Breast cancer has become a major cause of death among women. The lifetime risk of a woman developing this disease has been established as one in eight. The most useful way to reduce breast cancer death is to treat the disease as early as possible. Read More

    Direct inversion algorithm for focal plane scanning optical projection tomography.
    Biomed Opt Express 2017 Nov 31;8(11):5349-5358. Epub 2017 Oct 31.
    Electrical & Computer Engineering Department, University of California, Santa Barbara, CA 93106, USA.
    To achieve approximately parallel projection geometry, traditional optical projection tomography (OPT) requires the use of low numerical aperture (NA) objectives, which have a long depth-of-field at the expense of poor lateral resolution. Particularly promising methods to improve spatial resolution include ad-hoc post-processing filters that limit the effect of the system's MTF and focal-plane-scanning OPT (FPS-OPT), an alternative acquisition procedure that allows the use of higher NA objectives by limiting the effect of their shallow depth of field yet still assumes parallel projection rays during reconstruction. Here, we provide a detailed derivation that establishes the existence of a direct inversion formula for FPS-OPT. Read More

    Measuring blood oxygen saturation along a capillary vessel in human.
    Biomed Opt Express 2017 Nov 30;8(11):5342-5348. Epub 2017 Oct 30.
    Faculty of Biomedical Engineering, Technion - Israel Institute of Technology, Haifa 3200003, Israel.
    Measuring oxygen saturation in capillary vessels could provide valuable information on oxygen transport and tissue viability. Most spectroscopic measurement techniques, however, lack the spatial resolution to account for the small vessel dimensions within a scattering tissue and the steep gradients of oxygen saturation levels. Here, we developed a noninvasive technique for image-guided confocal measurement of the optical absorption spectrum from a small region that is comparable in size to the cross section of a single capillary vessel. Read More

    Dynamics of the human brain network revealed by time-frequency effective connectivity in fNIRS.
    Biomed Opt Express 2017 Nov 30;8(11):5326-5341. Epub 2017 Oct 30.
    Movement Disorders and Neurostimulation, Biomedical Statistics and Multimodal Signal Processing Unit, Department of Neurology, Focus Program Translational Neuroscience (FTN), Department of Neurology, Johannes Gutenberg University, Mainz, Germany.
    Functional near infrared spectroscopy (fNIRS) is a promising neuroimaging method for investigating networks of cortical regions over time. We propose a directed effective connectivity method (TPDC) allowing the capture of both time and frequency evolution of the brain's networks using fNIRS data acquired from healthy subjects performing a continuous finger-tapping task. Using this method we show the directed connectivity patterns among cortical motor regions involved in the task and their significant variations in the strength of information flow exchanges. Read More

    Time domain diffuse correlation spectroscopy with a high coherence pulsed source: in vivo and phantom results.
    Biomed Opt Express 2017 Nov 27;8(11):5311-5325. Epub 2017 Oct 27.
    ICFO-Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels (Barcelona), Spain.
    Diffuse correlation spectroscopy (DCS), combined with time-resolved reflectance spectroscopy (TRS) or frequency domain spectroscopy, aims at path length (i.e. depth) resolved, non-invasive and simultaneous assessment of tissue composition and blood flow. Read More

    Statistical independence in nonlinear model-based inversion for quantitative photoacoustic tomography.
    Biomed Opt Express 2017 Nov 27;8(11):5297-5310. Epub 2017 Oct 27.
    Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, WC1E 6BT, UK.
    The statistical independence between the distributions of different chromophores in tissue has previously been used for linear unmixing with independent component analysis (ICA). In this study, we propose exploiting this statistical property in a nonlinear model-based inversion method. The aim is to reduce the sensitivity of the inversion scheme to errors in the modelling of the fluence, and hence provide more accurate quantification of the concentration of independent chromophores. Read More

    Data-driven imaging of tissue inflammation using RGB-based hyperspectral reconstruction toward personal monitoring of dermatologic health.
    Biomed Opt Express 2017 Nov 26;8(11):5282-5296. Epub 2017 Oct 26.
    Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, USA.
    Sensitive and accurate assessment of dermatologic inflammatory hyperemia in otherwise grossly normal-appearing skin conditions is beneficial to laypeople for monitoring their own skin health on a regular basis, to patients for looking for timely clinical examination, and to primary care physicians or dermatologists for delivering effective treatments. We propose that mathematical hyperspectral reconstruction from RGB images in a simple imaging setup can provide reliable visualization of hemoglobin content in a large skin area. Without relying on a complicated, expensive, and slow hyperspectral imaging system, we demonstrate the feasibility of determining heterogeneous or multifocal areas of inflammatory hyperemia associated with experimental photocarcinogenesis in mice. Read More

    Multi-shaping technique reduces sidelobe magnitude in optical coherence tomography.
    Biomed Opt Express 2017 Nov 26;8(11):5267-5281. Epub 2017 Oct 26.
    Translational Imaging Center, University of Southern California, Los Angeles, CA 90089, USA.
    Shaping methods that are commonly used in Fourier-domain optical coherence tomography (FD-OCT) can suppress sidelobe artifacts in the axial direction, but they typically broaden the mainlobe of the point spread function (PSF) and reduce the axial resolution. To improve OCT image quality without this tradeoff, we have developed a multi-shaping technique that reduces the axial sidelobe magnitude dramatically and achieves better axial resolution than conventional shaping methods. This technique is robust and compatible in various FD-OCT imaging systems. Read More

    Common-path phase-sensitive optical coherence tomography provides enhanced phase stability and detection sensitivity for dynamic elastography.
    Biomed Opt Express 2017 Nov 26;8(11):5253-5266. Epub 2017 Oct 26.
    School of Optometry, University of Alabama at Birmingham, Birmingham, AL, USA.
    Phase-sensitive optical coherence elastography (PhS-OCE) is an emerging optical technique to quantify soft-tissue biomechanical properties. We implemented a common-path OCT design to enhance displacement sensitivity and optical phase stability for dynamic elastography imaging. The background phase stability was greater in common-path PhS-OCE (0. Read More

    Efficiency enhancement of Raman spectroscopy at long working distance by parabolic reflector.
    Biomed Opt Express 2017 Nov 26;8(11):5243-5252. Epub 2017 Oct 26.
    School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Dr. 637459, Singapore.
    Raman spectroscopy is well suited for readily revealing information about bio-samples. As such, this technique has been applied to a wide range of areas, particularly in bio-medical diagnostics. Raman scattering in bio-samples typically has a low signal level due to the nature of inelastic scattering of photons. Read More

    Multimodal nonlinear optical imaging of unstained retinas in the epi-direction with a sub-40 fs Yb-fiber laser.
    Biomed Opt Express 2017 Nov 26;8(11):5228-5242. Epub 2017 Oct 26.
    Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA.
    Ultrafast lasers have potential use in ophthalmology for diagnoses through non-invasive imaging as well as for surgical therapies or for evaluating pharmacological therapies. New ultrafast laser sources, operating at 1.07 μm and sub-40 fs pulse durations, offer exciting possibilities in multiphoton imagining of the retina as the bulk of the eye is relatively transparent to this wavelength, three-photon excitation is not absorbed by DNA, and this wavelength has a greater penetration depth compared to the commonly used 800 nm Ti:Sapphire laser. Read More

    Raman spectral post-processing for oral tissue discrimination - a step for an automatized diagnostic system.
    Biomed Opt Express 2017 Nov 24;8(11):5218-5227. Epub 2017 Oct 24.
    Biomedical Engineering Innovation Center - Biomedical Vibrational Spectroscopy Group, Universidade Brasil - UnBr - Rua Carolina Fonseca, 235 - 08230-030 - Itaquera, São Paulo/SP/ Visiting Professor Universidade Federal do Piauí - UFPI - Campus Ministro Petrônio Portella Departamento de Física - CCN Bairro Ininga Teresina, PI, CEP: 64049-550, Brazil.
    Most oral injuries are diagnosed by histopathological analysis of a biopsy, which is an invasive procedure and does not give immediate results. On the other hand, Raman spectroscopy is a real time and minimally invasive analytical tool with potential for the diagnosis of diseases. The potential for diagnostics can be improved by data post-processing. Read More

    Optical surface plasmon resonance sensor modified by mutant glucose/galactose-binding protein for affinity detection of glucose molecules.
    Biomed Opt Express 2017 Nov 24;8(11):5206-5217. Epub 2017 Oct 24.
    School of Precision Instrument and Opto-Electronics Engineering at Tianjin University, Tianjin 300072, China.
    Transdermal extraction of interstitial fluid (ISF) offers an attractive method for minimally invasive blood glucose monitoring. However, only a minute volume of ISF could be transdermally extracted, which is required to be diluted to form a manipulable volume of fluid for easy collection, transportation, and glucose detection. Therefore, a high-resolution glucose detection method is required for detecting glucose concentration in diluted ISF. Read More

    Label-free fiber optic optrode for the detection of class C β-lactamases expressed by drug resistant bacteria.
    Biomed Opt Express 2017 Nov 23;8(11):5191-5205. Epub 2017 Oct 23.
    Institute for Polymers, Composites and Biomaterials - National Council of Research, Portici, Italy.
    This paper reports the experimental assessment of an automated optical assay based on label free optical fiber optrodes for the fast detection of class C β-lactamases (AmpC BLs), actually considered as one of the most important sources of resistance to β-lactams antibiotics expressed by resistant bacteria. Reflection-type long period fiber gratings (RT-LPG) have been used as highly sensitive label free optrodes, while a higher affine boronic acid-based ligand was here selected to enhance the overall assay performances compared to those obtained in our first demonstration. In order to prove the feasibility analysis towards a fully automated optical assay, an engineered system was developed to simultaneously manipulate and interrogate multiple fiber optic optrodes in the different phases of the assay. Read More

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