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Biomedical Optics Express

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https://www.readbyqxmd.com/read/30319924/ciliary-muscle-thickness-profiles-derived-from-optical-coherence-tomography-images
#1
Sandra Wagner, Eberhart Zrenner, Torsten Strasser
The purpose of this study was to provide an in-depth analysis of the ciliary muscle's (CM) morphological changes during accommodation by evaluating CM thickness (CMT) profiles. The CM of 15 near-emmetropic subjects (age 20-39) was imaged via optical coherence tomography (OCT) during far (0 D) and near vision (3 D). A custom-made Java-based program was used for semi-automatic CM segmentation and thickness measurements. CMT profiles were generated to determine regions of the largest shape changes. The results revealed on average a thinning within the first 0...
October 1, 2018: Biomedical Optics Express
https://www.readbyqxmd.com/read/30319923/determination-of-confocal-profile-and-curved-focal-plane-for-oct-mapping-of-the-attenuation-coefficient
#2
Sabina Stefan, Ki-Soo Jeong, Collin Polucha, Nikos Tapinos, Steven A Toms, Jonghwan Lee
The attenuation coefficient has proven to be a useful tool in numerous biological applications, but accurate calculation is dependent on the characterization of the confocal effect. This study presents a method to precisely determine the confocal effect and its focal plane within a sample by examining the ratio of two optical coherence tomography (OCT) images. The method can be employed to produce a single-value estimate, or a 2D map of the focal plane accounting for the curvature or tilt within the sample...
October 1, 2018: Biomedical Optics Express
https://www.readbyqxmd.com/read/30319922/full-depth-spectral-domain-optical-coherence-tomography-technology-insensitive-to-phase-disturbance
#3
Luying Yi, Liqun Sun, Xianshun Ming, Mingli Zou
To achieve full-depth spectral domain optical coherence tomography in the case of strong environmental disturbance, the iterative phase-shifting (IPS) method and modified dispersion-coded (MDC) method are proposed in this work. In IPS, the precise amount of phase shift is retrieved by iteration, and the direction of the phase shift is determined by dispersion compensation. Conjugate mirror items and noise can be simultaneously eliminated by two captured interferograms, whereas only one of them can be removed in the traditional phase-shift method with two interferograms...
October 1, 2018: Biomedical Optics Express
https://www.readbyqxmd.com/read/30319921/constant-linear-velocity-spiral-scanning-for-near-video-rate-4d-oct-ophthalmic-and-surgical-imaging-with-isotropic-transverse-sampling
#4
Oscar M Carrasco-Zevallos, Christian Viehland, Brenton Keller, Ryan P McNabb, Anthony N Kuo, Joseph A Izatt
Ultrahigh speed optical coherence tomography (OCT) systems with >100 kHz A-scan rates can generate volumes rapidly with minimal motion artifacts and are well suited for 4D imaging (volumes through time) applications such as intra-operative imaging. In such systems, high OCT data acquisition efficiency (defined as the fraction of usable A-scans generated during the total acquisition time) is desired to maximize the volumetric frame rate and sampling pitch. However, current methods for beam scanning using non-resonant and resonant mirror scanners can result in severe scan distortion and transverse oversampling as well as require acquisition dead times, which limit the acquisition efficiency and performance of ultrahigh speed 4D OCT...
October 1, 2018: Biomedical Optics Express
https://www.readbyqxmd.com/read/30319920/inverse-matrix-based-phase-estimation-algorithm-for-structured-illumination-microscopy
#5
Ruizhi Cao, Youhua Chen, Wenjie Liu, Dazhao Zhu, Cuifang Kuang, Yingke Xu, Xu Liu
The fast imaging speed and low-intensity requirement of structured illumination microscopy (SIM) have made it one of the most widely used imaging tools in live cell imaging. In order to obtain a high fidelity reconstructed image, a precise estimation of the phase of the illumination pattern is required, especially in those structured illumination based techniques that rely on high-order harmonics to improve the resolution. This can be achieved in one of two fundamental ways. The first is to build a high-end control system capable of shifting a sinusoidal pattern with high precision, while the second is to apply estimation algorithms to determine how patterns shift during post-processing...
October 1, 2018: Biomedical Optics Express
https://www.readbyqxmd.com/read/30319919/use-of-a-dpss-er-yag-laser-for-the-selective-removal-of-composite-from-tooth-surfaces
#6
William A Fried, Kenneth H Chan, Cynthia L Darling, Daniel Fried
New diode-pumped solid state (DPSS) Er:YAG lasers have become available operating at high pulse repetition rates. These lasers are ideally suited for integration with laser scanning systems for the selective removal of dental decay and composite restorative materials from tooth surfaces. The purpose of this study was to determine if a DPSS Er:YAG laser system is suitable for the selective removal of composite from tooth surfaces. Relative ablation rates of composite and enamel were determined and composite was removed from tooth surfaces using a DPSS Er:YAG laser...
October 1, 2018: Biomedical Optics Express
https://www.readbyqxmd.com/read/30319918/near-infrared-probe-based-confocal-microendoscope-for-deep-tissue-imaging
#7
Jiafu Wang, Hua Li, Geng Tian, Yong Deng, Qian Liu, Ling Fu
In this work, a near-infrared probe-based confocal microendoscope (pCM) with a 785 nm laser source, a long working distance, and a probe with diameter of 2.6 mm that can be compatible with a conventional endoscope is demonstrated to produce deep-tissue images at cellular resolutions with enhanced contrast and signal-to-noise ratio. Theoretical simulations and experiments confirm that near-infrared light can optimize the image quality. Abundant details of mouse esophagus obtained at different depths demonstrate the system's ability to image deep tissues at cellular resolutions, which makes it possible to diagnose diseases in the digestive tract in real time, laying a solid foundation for clinical applications...
October 1, 2018: Biomedical Optics Express
https://www.readbyqxmd.com/read/30319917/use-of-raman-spectroscopy-to-screen-diabetes-mellitus-with-machine-learning-tools
#8
Edgar Guevara, Juan Carlos Torres-Galván, Miguel G Ramírez-Elías, Claudia Luevano-Contreras, Francisco Javier González
Type 2 diabetes mellitus (DM2) is one of the most widely prevalent diseases worldwide and is currently screened by invasive techniques based on enzymatic assays that measure plasma glucose concentration in a laboratory setting. A promising plan of action for screening DM2 is to identify molecular signatures in a non-invasive fashion. This work describes the application of portable Raman spectroscopy coupled with several supervised machine-learning techniques, to discern between diabetic patients and healthy controls (Ctrl), with a high degree of accuracy...
October 1, 2018: Biomedical Optics Express
https://www.readbyqxmd.com/read/30319916/superhydrophobic-silver-film-as-a-sers-substrate-for-the-detection-of-uric-acid-and-creatinine
#9
Yudong Lu, Changji Wu, Ruiyun You, Yang Wu, Huiying Shen, Lanjin Zhu, Shangyuan Feng
Superhydrophobic silver films were fabricated by silver-mirror reaction and surface functionalization with thiol. The thiol-functionalization significantly improved the hydrophobic property of the Ag films (AFS), and their contact angle values slightly increased with the extension of a thiol alkyl chain, reaching about 160°. The surface-enhanced Raman scattering (SERS) detection capacity of these films were investigated, and AFS-Dodec showed the best substrate for R6G molecule detection with the concentration limit of 10-11 M...
October 1, 2018: Biomedical Optics Express
https://www.readbyqxmd.com/read/30319915/upconversion-raster-scanning-microscope-for-long-wavelength-infrared-imaging-of-breast-cancer-microcalcifications
#10
Yu-Pei Tseng, Pascaline Bouzy, Christian Pedersen, Nick Stone, Peter Tidemand-Lichtenberg
Long-wavelength identification of microcalcifications in breast cancer tissue is demonstrated using a novel upconversion raster scanning microscope. The system consists of quantum cascade lasers (QCL) for illumination and an upconversion system for efficient, high-speed detection using a silicon detector. Absorbance spectra and images of regions of ductal carcinoma in situ (DCIS) from the breast have been acquired using both upconversion and Fourier-transform infrared (FTIR) systems. The spectral images are compared and good agreement is found between the upconversion and the FTIR systems...
October 1, 2018: Biomedical Optics Express
https://www.readbyqxmd.com/read/30319914/characterization-of-nad-p-h-and-fad-autofluorescence-signatures-in-a-langendorff-isolated-perfused-rat-heart-model
#11
João L Lagarto, Benjamin T Dyer, Clifford B Talbot, Nicholas S Peters, Paul M W French, Alexander R Lyon, Chris Dunsby
Autofluorescence spectroscopy is a promising label-free approach to characterize biological samples with demonstrated potential to report structural and biochemical alterations in tissues in a number of clinical applications. We report a characterization of the ex vivo autofluorescence fingerprint of cardiac tissue, exploiting a Langendorff-perfused isolated rat heart model to induce physiological insults to the heart, with a view to understanding how metabolic alterations affect the autofluorescence signals...
October 1, 2018: Biomedical Optics Express
https://www.readbyqxmd.com/read/30319913/characterization-of-coronary-artery-pathological-formations-from-oct-imaging-using-deep-learning
#12
Atefeh Abdolmanafi, Luc Duong, Nagib Dahdah, Ibrahim Ragui Adib, Farida Cheriet
Coronary artery disease is the number one health hazard leading to the pathological formations in coronary artery tissues. In severe cases, they can lead to myocardial infarction and sudden death. Optical Coherence Tomography (OCT) is an interferometric imaging modality, which has been recently used in cardiology to characterize coronary artery tissues providing high resolution ranging from 10 to 20 µm . In this study, we investigate different deep learning models for robust tissue characterization to learn the various intracoronary pathological formations caused by Kawasaki disease (KD) from OCT imaging...
October 1, 2018: Biomedical Optics Express
https://www.readbyqxmd.com/read/30319912/aberration-diverse-optical-coherence-tomography-for-suppression-of-multiple-scattering-and-speckle
#13
Siyang Liu, Michael R E Lamont, Jeffrey A Mulligan, Steven G Adie
Multiple scattering is a major barrier that limits the optical imaging depth in scattering media. In order to alleviate this effect, we demonstrate aberration-diverse optical coherence tomography (AD-OCT), which exploits the phase correlation between the deterministic signals from single-scattered photons to suppress the random background caused by multiple scattering and speckle. AD-OCT illuminates the sample volume with diverse aberrated point spread functions, and computationally removes these intentionally applied aberrations...
October 1, 2018: Biomedical Optics Express
https://www.readbyqxmd.com/read/30319911/system-based-on-the-contrast-of-purkinje-images-to-measure-corneal-and-lens-scattering
#14
Pau Santos, Juan A Martínez-Roda, Juan C Ondategui, Fernando Díaz-Doutón, Jorge A Ortiz Cazal, Meritxell Vilaseca
Current methods to measure intraocular scattering provide information on the total scattered light, which consists of the combined contributions originating from different ocular structures. In this work, we propose a technique for the objective and independent assessment of scattering caused by the cornea and the lens based on the analysis of the contrast of the third and fourth Purkinje images. The technique is preliminarily validated first by using artificial eyes with different levels of corneal and lens scattering; second, it is validated in eyes wearing customized contact lenses to simulate corneal scattering and eyes with nuclear cataracts...
October 1, 2018: Biomedical Optics Express
https://www.readbyqxmd.com/read/30319910/visual-acuity-of-pseudophakic-patients-predicted-from-in-vitro-measurements-of-intraocular-lenses-with-different-design
#15
Fidel Vega, Maria S Millán, Nuria Garzón, Irene Altemir, Francisco Poyales, Jose Manuel Larrosa
The optical quality of a set of IOLs (modeling set: one monofocal and two bifocals) was assessed through focus by the area under the modulation transfer function (MTFa) metric and related to the visual acuity (VA) defocus curves of pseudophakic patients implanted with said IOLs. A non-linear relationship between the MTFa and clinical VA was obtained with an asymptotic limit found to be the best VA achievable by the patients. Two mathematical fitting functions between clinical VA and MTFa were derived with high correlation coefficients (R2 ≥0...
October 1, 2018: Biomedical Optics Express
https://www.readbyqxmd.com/read/30319909/evaluation-of-a-transparent-cranial-implant-as-a-permanent-window-for-cerebral-blood-flow-imaging
#16
Nami Davoodzadeh, Mildred S Cano-Velázquez, David L Halaney, Carrie R Jonak, Devin K Binder, Guillermo Aguilar
Laser speckle imaging (LSI) of mouse cerebral blood flow was compared through a transparent nanocrystalline yttria-stabilized zirconia (nc-YSZ) cranial implant over time (at days 0, 14, and 28, n = 3 mice), and vs. LSI through native skull (at day 60, n = 1 mouse). The average sharpness of imaged vessels was found to remain stable, with relative change in sharpness under 7.69% ± 1.2% over 28 days. Through-implant images of vessels at day 60 appeared sharper and smaller on average, with microvessels clearly visible, compared to through-skull images where vessels appeared blurred and distorted...
October 1, 2018: Biomedical Optics Express
https://www.readbyqxmd.com/read/30319908/detection-of-exudates-in-fundus-photographs-with-imbalanced-learning-using-conditional-generative-adversarial-network
#17
Rui Zheng, Lei Liu, Shulin Zhang, Chun Zheng, Filiz Bunyak, Ronald Xu, Bin Li, Mingzhai Sun
Diabetic retinopathy (DR) is a leading cause of blindness worldwide. However, 90% of DR caused blindness can be prevented if diagnosed and intervened early. Retinal exudates can be observed at the early stage of DR and can be used as signs for early DR diagnosis. Deep convolutional neural networks (DCNNs) have been applied for exudate detection with promising results. However, there exist two main challenges when applying the DCNN based methods for exudate detection. One is the very limited number of labeled data available from medical experts, and another is the severely imbalanced distribution of data of different classes...
October 1, 2018: Biomedical Optics Express
https://www.readbyqxmd.com/read/30319907/photodynamic-opening-of-the-blood-brain-barrier-to-high-weight-molecules-and-liposomes-through-an-optical-clearing-skull-window
#18
Chao Zhang, Wei Feng, Elena Vodovozova, Daria Tretiakova, Ivan Boldyrevd, Yusha Li, Jurgen Kürths, Tingting Yu, Oxana Semyachkina-Glushkovskaya, Dan Zhu
The photodynamic (PD) effect has been reported to be efficient for the opening of the blood-brain barrier (BBB), which provides a new informative platform for developing perspective strategies towards brain disease therapy and drug delivery. However, this method is usually performed via craniotomy due to high scattering of the turbid skull. In this work, we employed a newly-developed optical clearing skull window for investigating non-invasive PD-induced BBB opening to high weight molecules and 100-nm fluid-phase liposomes containing ganglioside GM1...
October 1, 2018: Biomedical Optics Express
https://www.readbyqxmd.com/read/30319906/swept-wavelength-lasers-based-on-gasb-gain-chip-technology-for-non-invasive-biomedical-sensing-applications-in-the-1-7-2-5-%C3%AE-m-wavelength-range
#19
Augustinas Vizbaras, Ieva Šimonytė, Arūnas Miasojedovas, Augustinas Trinkūnas, Tadas Bučiūnas, Mindaugas Greibus, Greta Naujokaitė, Nicolas Torcheboeuf, Serge Droz, Dmitri Boiko, Žilvinas Dambrauskas, Antanas Gulbinas, Kristijonas Vizbaras
The infrared spectral region beyond 1.7 μm is of utmost interest for biomedical applications due to strong overtone and combination absorption bands in a variety of important biomolecules such as lactates, urea, glucose, albumin, etc. In this article, we report on recent progress in widely tunable swept-wavelength lasers based on type-I GaSb gain-chip technology, setting a new state-of-the-art in the 1.7 - 2.5 μm range laser sources. We provide an application example for the spectroscopic sensing of several biomolecules in a cuvette as well as an experimental demonstration of a non-invasive in-vivo sensing of human serum albumin through the skin...
October 1, 2018: Biomedical Optics Express
https://www.readbyqxmd.com/read/30319905/cortical-bone-quality-affectations-and-their-strength-impact-analysis-using-holographic-interferometry
#20
Cesar G Tavera Ruiz, Manuel H De La Torre-Ibarra, J M Flores-Moreno, Claudio Frausto-Reyes, Fernando Mendoza Santoyo
It is now accepted that bone strength is a complex property determined mainly by three factors: quantity, quality and turnover of the bone itself. Most of the patients who experience fractures due to fragility could never develop affectations related to bone mass density (i.e. osteoporosis). In this work, the effect of secondary bone strength affectations are analyzed by simulating the degradation of one or more principal components (organic and inorganic) while they are inspected with a nondestructive optical technique...
October 1, 2018: Biomedical Optics Express
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