Search our Database of Scientific Publications and Authors

I’m looking for a

    2428 results match your criteria Biomedical optics express[Journal]

    1 OF 49

    Adaptive optical versus spherical aberration corrections for in vivo brain imaging.
    Biomed Opt Express 2017 Aug 31;8(8):3891-3902. Epub 2017 Jul 31.
    Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia 20147, USA.
    Adjusting the objective correction collar is a widely used approach to correct spherical aberrations (SA) in optical microscopy. In this work, we characterized and compared its performance with adaptive optics in the context of in vivo brain imaging with two-photon fluorescence microscopy. We found that the presence of sample tilt had a deleterious effect on the performance of SA-only correction. Read More

    Comparison of pump-probe and hyperspectral imaging in unstained histology sections of pigmented lesions.
    Biomed Opt Express 2017 Aug 31;8(8):3882-3890. Epub 2017 Jul 31.
    Duke University, Department of Chemistry, Durham, NC, 27708, USA.
    Microscopic variations in melanin composition can be mapped through linear and nonlinear optical responses. Though instrumentation to measure linear attenuation is simple and inexpensive, the nonlinear response provides more degrees of freedom with which to spectroscopically resolve pigments. The objective of this study is to assess differences in imaging melanin contrast by comparing hyperspectral (linear) versus pump-probe (nonlinear) microscopy of unstained histology sections of pigmented lesions. Read More

    Improving mesoscopic fluorescence molecular tomography through data reduction.
    Biomed Opt Express 2017 Aug 28;8(8):3868-3881. Epub 2017 Jul 28.
    Department of Biomedical Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180, USA.
    Mesoscopic fluorescence molecular tomography (MFMT) is a novel imaging technique that aims at obtaining the 3-D distribution of molecular probes inside biological tissues at depths of a few millimeters. To achieve high resolution, around 100-150μm scale in turbid samples, dense spatial sampling strategies are required. However, a large number of optodes leads to sizable forward and inverse problems that can be challenging to compute efficiently. Read More

    Wide-field high-speed space-division multiplexing optical coherence tomography using an integrated photonic device.
    Biomed Opt Express 2017 Aug 28;8(8):3856-3867. Epub 2017 Jul 28.
    Department of Electrical and Computer Engineering, Lehigh University, 27 Memorial Drive W, Bethlehem, PA 18015, USA.
    Space-division multiplexing optical coherence tomography (SDM-OCT) is a recently developed parallel OCT imaging method in order to achieve multi-fold speed improvement. However, the assembly of fiber optics components used in the first prototype system was labor-intensive and susceptible to errors. Here, we demonstrate a high-speed SDM-OCT system using an integrated photonic chip that can be reliably manufactured with high precisions and low per-unit cost. Read More

    Increased prefrontal cortex connectivity during cognitive challenge assessed by fNIRS imaging.
    Biomed Opt Express 2017 Aug 25;8(8):3842-3855. Epub 2017 Jul 25.
    Institute of Clinical Experimental Research, Semmelweis University, 37-43 Tűzoltó Street, Budapest 1094, Hungary.
    In this study, functional near-infrared spectroscopy (fNIRS) and the graph theory approach were used to access the functional connectivity (FC) of the prefrontal cortex (PFC) in a resting state and during increased mental workload. For this very purpose, a pattern recognition-based test was developed, which elicited a strong response throughout the PFC during the test condition. FC parameters obtained during stimulation were found increased compared to those in a resting state after correlation based signal improvement (CBSI), which can attenuate those components of fNIRS signals which are unrelated to neural activity. Read More

    Microscope objective based 4π spectroscopic tissue scattering goniometry.
    Biomed Opt Express 2017 Aug 25;8(8):3828-3841. Epub 2017 Jul 25.
    Department of Biomedical Engineering, University of Wisconsin-Madison, 1550 Engineering Drive, Madison, WI 53706, USA.
    The measurement of optical scattering as a function of angle, goniometry, can provide a wealth of information about tissue. The goniometry technique described here measures the intensity profile at the pupil planes of two microscope objectives with a scattering sample between them. The maximum observable scattering angle is extended by employing off-axis illumination. Read More

    Differentiation of fibrotic liver tissue using laser-induced breakdown spectroscopy.
    Biomed Opt Express 2017 Aug 24;8(8):3816-3827. Epub 2017 Jul 24.
    Laboratorio de Hígado, Páncreas y Motilidad (HIPAM), Unidad de Investigación en Medicina Experimental, Facultad de Medicina-Universidad Nacional Autónoma de México (UNAM), Hospital General de México, Dr. Eduardo Liceaga, México.
    Hepatic cirrhosis is a major cause of morbidity and mortality worldwide due to hepatitis C, alcoholism and fatty liver disease associated with obesity. Assessment of hepatic fibrosis relies in qualitative histological evaluation of biopsy samples. This method is time-consuming and depends on the histopathologists' interpretation. Read More

    Line scanning, stage scanning confocal microscope (LSSSCM).
    Biomed Opt Express 2017 Aug 24;8(8):3807-3815. Epub 2017 Jul 24.
    Ronald O. Pearleman Department of Dermatology, New York University, 240 E. 38th St., New York, NY 10016, USA.
    For rapid pathological assessment of large surgical tissue excisions with cellular resolution, we present a line scanning, stage scanning confocal microscope (LSSSCM). LSSSCM uses no scanning mirrors. Laser light is focused with a single cylindrical lens to a line of diffraction-limited width directly into the (Z) sample focal plane, which is parallel to and near the flattened specimen surface. Read More

    Method for quantitative assessment of retinal vessel tortuosity in optical coherence tomography angiography applied to sickle cell retinopathy.
    Biomed Opt Express 2017 Aug 24;8(8):3796-3806. Epub 2017 Jul 24.
    Department of Ophthalmology, University of Southern California, CA, USA.
    Tortuosity is an important geometric vessel parameter and among the first microvascular alterations observed in various retinopathies. In the current study, a quantitative vessel tortuosity index (VTI) based on a combination of local and global centerline features is presented. Performance of VTI and previously established tortuosity indices were compared against human observers' evaluation of tortuosity. Read More

    Toward whole-body quantitative photoacoustic tomography of small-animals with multi-angle light-sheet illuminations.
    Biomed Opt Express 2017 Aug 24;8(8):3778-3795. Epub 2017 Jul 24.
    College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China.
    Several attempts to achieve the quantitative photoacoustic tomography (q-PAT) have been investigated using point sources or a single-angle wide-field illumination. However, these schemes normally suffer from low signal-to-noise ratio (SNR) or poor quantification in imaging applications on large-size domains, due to the limitation of ANSI-safety incidence and incompleteness in the data acquisition. We herein present a q-PAT implementation that uses multi-angle light-sheet illuminations and calibrated recovering-and-averaging iterations. Read More

    Similarity regularized sparse group lasso for cup to disc ratio computation.
    Biomed Opt Express 2017 Aug 20;8(8):3763-3777. Epub 2017 Jul 20.
    Singapore Eye Research Institute, Singapore National Eye Centre, Singapore.
    Automatic cup to disc ratio (CDR) computation from color fundus images has shown to be promising for glaucoma detection. Over the past decade, many algorithms have been proposed. In this paper, we first review the recent work in the area and then present a novel similarity-regularized sparse group lasso method for automated CDR estimation. Read More

    High-sensitivity detection of cardiac troponin I with UV LED excitation for use in point-of-care immunoassay.
    Biomed Opt Express 2017 Aug 20;8(8):3749-3762. Epub 2017 Jul 20.
    Technical University of Denmark, Frederiksborgvej 399, 4000 Roskilde, Denmark.
    High-sensitivity cardiac troponin assay development enables determination of biological variation in healthy populations, more accurate interpretation of clinical results and points towards earlier diagnosis and rule-out of acute myocardial infarction. In this paper, we report on preliminary tests of an immunoassay analyzer employing an optimized LED excitation to measure on a standard troponin I and a novel research high-sensitivity troponin I assay. The limit of detection is improved by factor of 5 for standard troponin I and by factor of 3 for a research high-sensitivity troponin I assay, compared to the flash lamp excitation. Read More

    Visualization of laser tattoo removal treatment effects in a mouse model by two-photon microscopy.
    Biomed Opt Express 2017 Aug 20;8(8):3735-3748. Epub 2017 Jul 20.
    Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, San 31, Hyoja-dong, Nam-gu, Pohang, Gyeongbuk 790-784, South Korea.
    Laser tattoo removal is an effective method of eliminating tattoo particles in the skin. However, laser treatment cannot always remove the unwanted tattoo completely, and there are risks of either temporary or permanent side effects. Studies using preclinical animal models could provide detailed information on the effects of laser treatment in the skin, and might help to minimize side effects in clinical practices. Read More

    In-silico and in-vitro investigation of a photonic monitor for intestinal perfusion and oxygenation.
    Biomed Opt Express 2017 Aug 19;8(8):3714-3734. Epub 2017 Jul 19.
    Texas A&M University, Optical Biosensing Lab, Biomedical Engineering, 5045 Emerging Technologies Building 3120 TAMU, College Station 77843, USA.
    The quantification of visceral organ oxygenation after trauma-related systemic hypovolemia and shock is critical to enable effective resuscitation. In this work, a photoplethysmography-based (PPG) sensor was specifically designed for probing the perfusion and oxygenation condition of intestinal tissue with the ultimate goal to monitor patients post trauma to guide resuscitation. Through Monte Carlo modeling, suitable optofluidic phantoms were determined, the wavelength and separation distance for the sensor was optimized, and sensor performance for the quantification of tissue perfusion and oxygenation was tested on the in-vitro phantom. Read More

    Label-free optical detection of action potential in mammalian neurons.
    Biomed Opt Express 2017 Aug 19;8(8):3700-3713. Epub 2017 Jul 19.
    Department of Bioengineering, University of Texas at Arlington, TX, USA.
    We describe an optical technique for label-free detection of the action potential in cultured mammalian neurons. Induced morphological changes due to action potential propagation in neurons are optically interrogated with a phase sensitive interferometric technique. Optical recordings composed of signal pulses mirror the electrical spike train activity of individual neurons in a network. Read More

    Whole blood clot optical clearing for nondestructive 3D imaging and quantitative analysis.
    Biomed Opt Express 2017 Aug 17;8(8):3671-3686. Epub 2017 Jul 17.
    Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN 46556, USA.
    A technological revolution in both light and electron microscopy imaging now allows unprecedented views of clotting, especially in animal models of hemostasis and thrombosis. However, our understanding of three-dimensional high-resolution clot structure remains incomplete since most of our recent knowledge has come from studies of relatively small clots or thrombi, due to the optical impenetrability of clots beyond a few cell layers in depth. Here, we developed an optimized optical clearing method termed cCLOT that renders large whole blood clots transparent and allows confocal imaging as deep as one millimeter inside the clot. Read More

    Fluorescence depth estimation from wide-field optical imaging data for guiding brain tumor resection: a multi-inclusion phantom study.
    Biomed Opt Express 2017 Aug 14;8(8):3656-3670. Epub 2017 Jul 14.
    Thayer School of Engineering, Dartmouth College, 14 Engineering Dr. Hanover, NH 03755, USA.
    Studies have shown that fluorescent agents demarcate tumor from surrounding brain tissue and offer intraoperative guidance during resection. However, visualization of fluorescence signal from tumor below the surgical surface or through the appearance of blood in the surgical field is challenging. We have previously described red light imaging techniques for estimating fluorescent depths in turbid media. Read More

    Quantitatively characterizing the microstructural features of breast ductal carcinoma tissues in different progression stages by Mueller matrix microscope.
    Biomed Opt Express 2017 Aug 13;8(8):3643-3655. Epub 2017 Jul 13.
    Shenzhen Key Laboratory for Minimal Invasive Medical Technologies, Institute of Optical Imaging and Sensing, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China.
    Polarization imaging has been recognized as a potentially powerful technique for probing the microstructural information and optical properties of complex biological specimens. Recently, we have reported a Mueller matrix microscope by adding the polarization state generator and analyzer (PSG and PSA) to a commercial transmission-light microscope, and applied it to differentiate human liver and cervical cancerous tissues with fibrosis. In this paper, we apply the Mueller matrix microscope for quantitative detection of human breast ductal carcinoma samples at different stages. Read More

    ReLayNet: retinal layer and fluid segmentation of macular optical coherence tomography using fully convolutional networks.
    Biomed Opt Express 2017 Aug 13;8(8):3627-3642. Epub 2017 Jul 13.
    Computer Aided Medical Procedures, Technische Universität München, Munich, Germany.
    Optical coherence tomography (OCT) is used for non-invasive diagnosis of diabetic macular edema assessing the retinal layers. In this paper, we propose a new fully convolutional deep architecture, termed ReLayNet, for end-to-end segmentation of retinal layers and fluid masses in eye OCT scans. ReLayNet uses a contracting path of convolutional blocks (encoders) to learn a hierarchy of contextual features, followed by an expansive path of convolutional blocks (decoders) for semantic segmentation. Read More

    Classification of biological micro-objects using optical coherence tomography: in silico study.
    Biomed Opt Express 2017 Aug 10;8(8):3606-3626. Epub 2017 Jul 10.
    Department of Medical Physics and Biomedical Engineering, University College London, Malet Place, Gower Street, London WC1E 6BT, UK.
    We report on the development of a technique for differentiating between biological micro-objects using a rigorous, full-wave model of OCT image formation. We model an existing experimental prototype which uses OCT to interrogate a microfluidic chip containing the blood cells. A full-wave model is required since the technique uses light back-scattered by a scattering substrate, rather than by the cells directly. Read More

    qF-SSOP: real-time optical property corrected fluorescence imaging.
    Biomed Opt Express 2017 Aug 10;8(8):3597-3605. Epub 2017 Jul 10.
    Department of Surgery, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA 02115, USA.
    Fluorescence imaging is well suited to provide image guidance during resections in oncologic and vascular surgery. However, the distorting effects of tissue optical properties on the emitted fluorescence are poorly compensated for on even the most advanced fluorescence image guidance systems, leading to subjective and inaccurate estimates of tissue fluorophore concentrations. Here we present a novel fluorescence imaging technique that performs real-time (i. Read More

    Plastic embedding immunolabeled large-volume samples for three-dimensional high-resolution imaging.
    Biomed Opt Express 2017 Aug 10;8(8):3583-3596. Epub 2017 Jul 10.
    Britton Chance Center for Biomedical Photonics, School of Engineering Sciences, Wuhan National Laboratory for Optoelectronics-Huazhong University of Science and Technology, Wuhan 430074, China.
    High-resolution three-dimensional biomolecule distribution information of large samples is essential to understanding their biological structure and function. Here, we proposed a method combining large sample resin embedding with iDISCO immunofluorescence staining to acquire the profile of biomolecules with high spatial resolution. We evaluated the compatibility of plastic embedding with an iDISCO staining technique and found that the fluorophores and the neuronal fine structures could be well preserved in the Lowicryl HM20 resin, and that numerous antibodies and fluorescent tracers worked well upon Lowicryl HM20 resin embedding. Read More

    Optical coherence tomography angiography of retinal vascular occlusions produced by imaging-guided laser photocoagulation.
    Biomed Opt Express 2017 Aug 7;8(8):3571-3582. Epub 2017 Jul 7.
    Department of Biomedical Engineering, Northwestern University, Evanston, IL, USA.
    Retinal vascular occlusive diseases represent a major form of vision loss worldwide. Rodent models of these diseases have traditionally relied upon a slit-lamp biomicroscope to help visualize the fundus and subsequently aid delivery of high-power laser shots to a target vessel. Here we describe a multimodal imaging system that can produce, image, and monitor retinal vascular occlusions in rodents. Read More

    Mueller matrix polarimetry for characterizing microstructural variation of nude mouse skin during tissue optical clearing.
    Biomed Opt Express 2017 Aug 7;8(8):3559-3570. Epub 2017 Jul 7.
    Shenzhen Key Laboratory for Minimal Invasive Medical Technologies, Institute of Optical Imaging and Sensing, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China.
    We investigate the polarization features corresponding to changes in the microstructure of nude mouse skin during immersion in a glycerol solution. By comparing the Mueller matrix imaging experiments and Monte Carlo simulations, we examine in detail how the Mueller matrix elements vary with the immersion time. The results indicate that the polarization features represented by Mueller matrix elements m22&m33&m44 and the absolute values of m34&m43 are sensitive to the immersion time. Read More

    Sensing viruses using terahertz nano-gap metamaterials.
    Biomed Opt Express 2017 Aug 7;8(8):3551-3558. Epub 2017 Jul 7.
    Department of Physics and Department of Energy Systems Research, Ajou University, Suwon 16499, South Korea.
    We demonstrate highly sensitive detection of viruses using terahertz split-ring resonators with various capacitive gap widths. Two types of viruses, with sizes ranging from 60 nm (PRD1) to 30 nm (MS2), were detected at low densities on the metamaterial surface. The dielectric constants of the virus layers in the THz frequency range were first measured using thick films, and the large values found identified them as efficient target substances for dielectric sensing. Read More

    Adapting Bobbert-Vlieger model to spectroscopic ellipsometry of gold nanoparticles with bio-organic shells.
    Biomed Opt Express 2017 Aug 3;8(8):3538-3550. Epub 2017 Jul 3.
    International Iberian Nanotechnology Laboratory (INL), Av. Mestre José Veiga, 4715-330 Braga, Portugal.
    We investigate spectroscopic imaging ellipsometry for monitoring biomolecules at surfaces of nanoparticles. For the modeling of polarimetric light scattering off surface-adsorbed core-shell nanoparticles, we employ an extension of the exact solution for the scattering by particles near a substrate presented by Bobbert and Vlieger, which offers insight beyond that of the Maxwell-Garnett effective medium approximation. Varying thickness and refractive index of a model bio-organic shell results in systematic and characteristic changes in spectroscopic parameters [Formula: see text] and [Formula: see text]. Read More

    Optimizing pulse compressibility in completely all-fibered Ytterbium chirped pulse amplifiers for in vivo two photon laser scanning microscopy.
    Biomed Opt Express 2017 Aug 3;8(8):3526-3537. Epub 2017 Jul 3.
    Photonics Institute, TU Wien, Gusshausstrasse 27-29/387, 1040 Vienna, Austria.
    A simple and completely all-fiber Yb chirped pulse amplifier that uses a dispersion matched fiber stretcher and a spliced-on hollow core photonic bandgap fiber compressor is applied in nonlinear optical microscopy. This stretching-compression approach improves compressibility and helps to maximize the fluorescence signal in two-photon laser scanning microscopy as compared with approaches that use standard single mode fibers as stretcher. We also show that in femtosecond all-fiber systems, compensation of higher order dispersion terms is relevant even for pulses with relatively narrow bandwidths for applications relying on nonlinear optical effects. Read More

    Blood oxygenation and flow measurements using a single 720-nm tunable V-cavity laser.
    Biomed Opt Express 2017 Aug 3;8(8):3516-3525. Epub 2017 Jul 3.
    State Key Laboratory of Modern Optical Instrumentation, Centre for Integrated Optoelectronics, College of Optical Science and Engineering, Zhejiang University, Hangzhou, 310027, China.
    We propose and demonstrate a single-laser-based sensing method for measuring both blood oxygenation and microvascular blood flow. Based on the optimal wavelength range found from theoretical analysis on differential absorption based blood oxygenation measurement, we designed and fabricated a 720-nm-band wavelength tunable V-cavity laser. Without any grating or bandgap engineering, the laser has a wavelength tuning range of 14. Read More

    Label-free photoacoustic imaging of the cardio-cerebrovascular development in the embryonic zebrafish.
    Biomed Opt Express 2017 Apr 30;8(4):2359-2367. Epub 2017 Mar 30.
    School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, China.
    Zebrafish play an important role in biology, pharmacology, toxicology, and medicine. The cardio-cerebrovascular development of zebrafish is particularly critical to understand both brain disorders and cardiovascular diseases in human. In this paper, we applied optical resolution photoacoustic microscopy (ORPAM) to image the whole-body vasculature of the embryonic zebrafish with a special focus on the development of the cardio-cerebrovascular system. Read More

    Simulation study on compressive laminar optical tomography for cardiac action potential propagation.
    Biomed Opt Express 2017 Apr 24;8(4):2339-2358. Epub 2017 Mar 24.
    Department of Bioengineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.
    To measure the activity of tissue at the microscopic level, laminar optical tomography (LOT), which is a microscopic form of diffuse optical tomography, has been developed. However, obtaining sufficient recording speed to determine rapidly changing dynamic activity remains major challenges. For a high frame rate of the reconstructed data, we here propose a new LOT method using compressed sensing theory, called compressive laminar optical tomography (CLOT), in which novel digital micromirror device-based illumination and data reduction in a single reconstruction are applied. Read More

    Fluorescein as a topical fluorescent contrast agent for quantitative microendoscopic inspection of colorectal epithelium.
    Biomed Opt Express 2017 Apr 24;8(4):2324-2338. Epub 2017 Mar 24.
    Department of Biomedical Engineering, University of Arkansas, 1 University Blvd., Fayetteville, AR 72701, USA.
    Fiber bundle microendoscopic imaging of colorectal tissue has shown promising results, for both qualitative and quantitative analysis. A quantitative image quality control and image feature extraction algorithm was previously designed for quantitative image feature analysis of proflavine-stained ex vivo colorectal tissue. We investigated fluorescein as an alternative topical stain. Read More

    Detection theory for accurate and non-invasive skin cancer diagnosis using dynamic thermal imaging.
    Biomed Opt Express 2017 Apr 22;8(4):2301-2323. Epub 2017 Mar 22.
    Center for High Technology Materials, University of New Mexico, 1313 Goddard Street SE, MSC04 2710, Albuquerque, NM 87106-4343, USA.
    Skin cancer is the most common cancer in the United States with over 3.5M annual cases. Presently, visual inspection by a dermatologist has good sensitivity (> 90%) but poor specificity (< 10%), especially for melanoma, which leads to a high number of unnecessary biopsies. Read More

    Handheld optical coherence tomography angiography.
    Biomed Opt Express 2017 Apr 22;8(4):2287-2300. Epub 2017 Mar 22.
    Casey Eye Institute, Oregon Health and Science University, 3375 SW Terwilliger Blvd, Portland, OR 97239, USA.
    We developed a handheld optical coherence tomography angiography (OCTA) system using a 100-kHz swept-source laser. The handheld probe weighs 0.4 kg and measures 20. Read More

    Noninvasive in vivo monitoring of collagenase induced intracerebral hemorrhage by photoacoustic tomography.
    Biomed Opt Express 2017 Apr 21;8(4):2276-2286. Epub 2017 Mar 21.
    School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu, Sichuan, China.
    Photoacoustic tomography (PAT) is an emerging noninvasive biomedical imaging modality that can be used for visualizing the structure and function of brain in high resolution. Here we report an application of PAT to imaging intracerebral hemorrhage (ICH) in a mouse model. In vivo photoacoustic images were obtained in mice with right basal ganglia hemorrhage induced by microinjection of collagenase. Read More

    Wavefront sensorless adaptive optics OCT with the DONE algorithm for in vivo human retinal imaging [Invited].
    Biomed Opt Express 2017 Apr 21;8(4):2261-2275. Epub 2017 Mar 21.
    School of Engineering Science, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A 1S6, Canada.
    In this report, which is an international collaboration of OCT, adaptive optics, and control research, we demonstrate the Data-based Online Nonlinear Extremum-seeker (DONE) algorithm to guide the image based optimization for wavefront sensorless adaptive optics (WFSL-AO) OCT for in vivo human retinal imaging. The ocular aberrations were corrected using a multi-actuator adaptive lens after linearization of the hysteresis in the piezoelectric actuators. The DONE algorithm succeeded in drastically improving image quality and the OCT signal intensity, up to a factor seven, while achieving a computational time of 1 ms per iteration, making it applicable for many high speed applications. Read More

    Photoacoustic reflection artifact reduction using photoacoustic-guided focused ultrasound: comparison between plane-wave and element-by-element synthetic backpropagation approach.
    Biomed Opt Express 2017 Apr 20;8(4):2245-2260. Epub 2017 Mar 20.
    Biomedical Photonic Imaging Group, MIRA institute for Biomedical Technology and Technical Medicine, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
    Reflection artifacts caused by acoustic inhomogeneities constitute a major problem in epi-mode biomedical photoacoustic imaging. Photoacoustic transients from the skin and superficial optical absorbers traverse into the tissue and reflect off echogenic structures to generate reflection artifacts. These artifacts cause difficulties in the interpretation of images and reduce contrast and imaging depth. Read More

    In vivo photoacoustics and high frequency ultrasound imaging of mechanical high intensity focused ultrasound (HIFU) ablation.
    Biomed Opt Express 2017 Apr 20;8(4):2235-2244. Epub 2017 Mar 20.
    Department of Radiology and Nuclear Medicine, Medical UltraSound Imaging Centre, Radboud University Nijmegen Medical Centre, Netherlands.
    The thermal effect of high intensity focused ultrasound (HIFU) has been clinically exploited over a decade, while the mechanical HIFU is still largely confined to laboratory investigations. This is in part due to the lack of adequate imaging techniques to better understand the in-vivo pathological and immunological effects caused by the mechanical treatment. In this work, we explore the use of high frequency ultrasound (US) and photoacoustics (PA) as a potential tool to evaluate the effect of mechanical ablation in-vivo, e. Read More

    Changes in optical properties of electroporated cells as revealed by digital holographic microscopy.
    Biomed Opt Express 2017 Apr 16;8(4):2222-2234. Epub 2017 Mar 16.
    Biophysics and Cellular Biotechnology Dept., Faculty of Medicine, Carol Davila University of Medicine and Pharmacy, 8 Eroii Sanitari Blvd., Bucharest 050474, Romania.
    Changes in optical and shape-related characteristics of B16F10 cells after electroporation were investigated using digital holographic microscopy (DHM). Bipolar rectangular pulses specific for electrochemotherapy were used. Electroporation was performed in an "off-axis" DHM set-up without using exogenous markers. Read More

    Enhancement of accuracy in shape sensing of surgical needles using optical frequency domain reflectometry in optical fibers.
    Biomed Opt Express 2017 Apr 16;8(4):2210-2221. Epub 2017 Mar 16.
    The Fabulas Laboratory, Department of Engineering Physics, Polytechnique Montréal, 2900 Édouard-Montpetit, Qc, Montreal H3T 1J4, Canada.
    We demonstrate a novel approach to enhance the precision of surgical needle shape tracking based on distributed strain sensing using optical frequency domain reflectometry (OFDR). The precision enhancement is provided by using optical fibers with high scattering properties. Shape tracking of surgical tools using strain sensing properties of optical fibers has seen increased attention in recent years. Read More

    Airway compliance measured by anatomic optical coherence tomography.
    Biomed Opt Express 2017 Apr 15;8(4):2195-2209. Epub 2017 Mar 15.
    Department of Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3216, USA.
    Quantification of airway compliance can aid in the diagnosis and treatment of obstructive airway disorders by detecting regions vulnerable to collapse. Here we evaluate the ability of a swept-source anatomic optical coherence tomography (SSaOCT) system to quantify airway cross-sectional compliance (CC) by measuring changes in the luminal cross-sectional area (CSA) under physiologically relevant pressures of 10-40 cmH2O. The accuracy and precision of CC measurements are determined using simulations of non-uniform rotation distortion (NURD) endemic to endoscopic scanning, and experiments performed in a simplified tube phantom and ex vivo porcine tracheas. Read More

    Identification of melanoma cells: a method based in mean variance of signatures via spectral densities.
    Biomed Opt Express 2017 Apr 15;8(4):2185-2194. Epub 2017 Mar 15.
    Departamento de Ciencias Químico Biológicas, Universidad de Sonora (UNISON), Luis Encinas y Rosales S/N, Col. Centro, C.P. 83000, Hermosillo, Sonora, Mexico.
    In this paper a new methodology to detect and differentiate melanoma cells from normal cells through 1D-signatures averaged variances calculated with a binary mask is presented. The sample images were obtained from histological sections of mice melanoma tumor of 4 [Formula: see text] in thickness and contrasted with normal cells. The results show that melanoma cells present a well-defined range of averaged variances values obtained from the signatures in the four conditions used. Read More

    Three-dimensional OCT based guinea pig eye model: relating morphology and optics.
    Biomed Opt Express 2017 Apr 15;8(4):2173-2184. Epub 2017 Mar 15.
    Instituto de Óptica "Daza de Valdés," Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain.
    Custom Spectral Optical Coherence Tomography (SOCT) provided with automatic quantification and distortion correction algorithms was used to measure the 3-D morphology in guinea pig eyes (n = 8, 30 days; n = 5, 40 days). Animals were measured awake in vivo under cyclopegia. Measurements showed low intraocular variability (<4% in corneal and anterior lens radii and <8% in the posterior lens radii, <1% interocular distances). Read More

    Can time-resolved NIRS provide the sensitivity to detect brain activity during motor imagery consistently?
    Biomed Opt Express 2017 Apr 13;8(4):2162-2172. Epub 2017 Mar 13.
    Department of Medical Biophysics, Western University, London, ON, Canada.
    Previous functional magnetic resonance imaging (fMRI) studies have shown that a subgroup of patients diagnosed as being in a vegetative state are aware and able to communicate by performing a motor imagery task in response to commands. Due to the fMRI's cost and accessibility, there is a need for exploring different imaging modalities that can be used at the bedside. A promising technique is functional near infrared spectroscopy (fNIRS) that has been successfully applied to measure brain oxygenation in humans. Read More

    Brain tumor delineation enhanced by moxifloxacin-based two-photon/CARS combined microscopy.
    Biomed Opt Express 2017 Apr 9;8(4):2148-2161. Epub 2017 Mar 9.
    Department of Biomedical Science and Engineering, Institute of Integrated Technology (IIT), Gwangju Institute of Science and Technology (GIST), 123 Cheomdangwagi-Ro, Buk-gu, Gwangju 61005, South Korea.
    Delineating brain tumor margin is critical for maximizing tumor removal while sparing adjacent normal tissue for better clinical outcome. We describe the use of moxifloxacin-based two-photon (TP)/coherent anti-Stokes Raman scattering (CARS) combined microscopy for differentiating normal mouse brain tissue from metastatic brain tumor tissue based on histoarchitectural and biochemical differences. Moxifloxacin, an FDA-approved compound, was used to label cells in the brain, and moxifloxacin-based two-photon microscopy (TPM) revealed tumor lesions with significantly high cellular density and invading edges in a metastatic brain tumor model. Read More

    Effect of higher-order aberrations and intraocular scatter on contrast sensitivity measured with a single instrument.
    Biomed Opt Express 2017 Apr 9;8(4):2138-2147. Epub 2017 Mar 9.
    The Key Laboratory on Adaptive Optics, Chinese Academy of Sciences, Chengdu 610209, China.
    Higher-order aberrations (HOAs) and intraocular scatter lead to the degradation of image quality on the retina, and consequently deteriorate subjective visual performance. In this article, we modified an adaptive optics double-pass system to combine objective and subjective visual testing capabilities. Employing the modified DP system, we investigated the effects of HOAs and intraocular scatter on contrast sensitivity. Read More

    High-dynamic-range fluorescence laminar optical tomography (HDR-FLOT).
    Biomed Opt Express 2017 Apr 9;8(4):2124-2137. Epub 2017 Mar 9.
    Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742 USA.
    Three-dimensional fluorescence laminar optical tomography (FLOT) can achieve resolutions of 100-200 µm and penetration depths of 2-3 mm. FLOT has been used in tissue engineering, neuroscience, as well as oncology. The limited dynamic range of the charge-coupled device-based system makes it difficult to image fluorescent samples with a large concentration difference, limits its penetration depth, and diminishes the quantitative accuracy of 3D reconstruction data. Read More

    3D reconstruction of cystoscopy videos for comprehensive bladder records.
    Biomed Opt Express 2017 Apr 8;8(4):2106-2123. Epub 2017 Mar 8.
    Dept. of Electrical Engineering, Stanford University, Stanford, CA, USA.
    White light endoscopy is widely used for diagnostic imaging of the interior of organs and body cavities, but the inability to correlate individual 2D images with 3D organ morphology limits its utility for quantitative or longitudinal studies of disease physiology or cancer surveillance. As a result, most endoscopy videos, which carry enormous data potential, are used only for real-time guidance and are discarded after collection. We present a computational method to reconstruct and visualize a 3D model of organs from an endoscopic video that captures the shape and surface appearance of the organ. Read More

    High temporal resolution aberrometry in a 50-eye population and implications for adaptive optics error budget.
    Biomed Opt Express 2017 Apr 7;8(4):2088-2105. Epub 2017 Mar 7.
    ONERA - the French Aerospace Lab, Châtillon, France.
    We formed a database gathering the wavefront aberrations of 50 healthy eyes measured with an original custom-built Shack-Hartmann aberrometer at a temporal frequency of 236 Hz, with 22 lenslets across a 7-mm diameter pupil, for a duration of 20 s. With this database, we draw statistics on the spatial and temporal behavior of the dynamic aberrations of the eye. Dynamic aberrations were studied on a 5-mm diameter pupil and on a 3. Read More

    Noise-bias and polarization-artifact corrected optical coherence tomography by maximum a-posteriori intensity estimation.
    Biomed Opt Express 2017 Apr 3;8(4):2069-2087. Epub 2017 Mar 3.
    Computational Optics Group, University of Tsukuba, Tennodai 1-1-1, Tsukuba, Ibaraki, 305-8573, Japan.
    We propose using maximum a-posteriori (MAP) estimation to improve the image signal-to-noise ratio (SNR) in polarization diversity (PD) optical coherence tomography. PD-detection removes polarization artifacts, which are common when imaging highly birefringent tissue or when using a flexible fiber catheter. However, dividing the probe power to two polarization detection channels inevitably reduces the SNR. Read More

    Comparison of vision through surface modulated and spatial light modulated multifocal optics.
    Biomed Opt Express 2017 Apr 3;8(4):2055-2068. Epub 2017 Mar 3.
    Institute of Optics, Spanish National Research Council (CSIC), Serrano, 121, Madrid 28006, Spain.
    Spatial-light-modulators (SLM) are increasingly used as active elements in adaptive optics (AO) systems to simulate optical corrections, in particular multifocal presbyopic corrections. In this study, we compared vision with lathe-manufactured multi-zone (2-4) multifocal, angularly and radially, segmented surfaces and through the same corrections simulated with a SLM in a custom-developed two-active-element AO visual simulator. We found that perceived visual quality measured through real manufactured surfaces and SLM-simulated phase maps corresponded highly. Read More

    1 OF 49