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Biomedical Optics Express

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https://www.readbyqxmd.com/read/29026684/combined-multi-distance-frequency-domain-and-diffuse-correlation-spectroscopy-system-with-simultaneous-data-acquisition-and-real-time-analysis
#1
Stefan A Carp, Parisa Farzam, Norin Redes, Dennis M Hueber, Maria Angela Franceschini
Frequency domain near infrared spectroscopy (FD-NIRS) and diffuse correlation spectroscopy (DCS) have emerged as synergistic techniques for the non-invasive assessment of tissue health. Combining FD-NIRS oximetry with DCS measures of blood flow, the tissue oxygen metabolic rate can be quantified, a parameter more closely linked to underlying physiology and pathology than either NIRS or DCS estimates alone. Here we describe the first commercially available integrated instrument, called the "MetaOx", designed to enable simultaneous FD-NIRS and DCS measurements at rates of 10 + Hz, and offering real-time data evaluation...
September 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/29026683/high-sensitivity-optical-measurement-of-skin-gloss
#2
Anna Ezerskaia, Arno Ras, Pascal Bloemen, Silvania F Pereira, H Paul Urbach, Babu Varghese
We demonstrate a low-cost optical method for measuring the gloss properties with improved sensitivity in the low gloss regime, relevant for skin gloss properties. The gloss estimation method is based on, on the one hand, the slope of the intensity gradient in the transition regime between specular and diffuse reflection and on the other on the sum over the intensities of pixels above threshold, derived from a camera image obtained using unpolarized white light illumination. We demonstrate the improved sensitivity of the two proposed methods using Monte Carlo simulations and experiments performed on ISO gloss calibration standards with an optical prototype...
September 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/29026682/wavelength-dependent-optical-properties-of-melanosomes-in-retinal-pigmented-epithelium-and-their-changes-with-melanin-bleaching-a-numerical-study
#3
Weiye Song, Lei Zhang, Steve Ness, Ji Yi
In this paper, we present the first numerical study on full metrics of wavelength-dependent optical properties of melanosomes in retinal pigmented epithelial (RPE) cells. T-matrix method was used to simulate the spheroidal shapes of mature melanosomes, and the complex refractive index was calculated by a subtractive Kramers-Kronig relation for melanin. The validity of the method was first confirmed by Mie theory, and corroborated by a comparison between visible light and near infrared (NIR) optical coherence tomography (OCT) on human retinal imaging...
September 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/29026681/resolving-adjacent-nanophosphors-of-different-concentrations-by-excitation-based-cone-beam-x-ray-luminescence-tomography
#4
Peng Gao, Huangsheng Pu, Junyan Rong, Wenli Zhang, Tianshuai Liu, Wenlei Liu, Yuanke Zhang, Hongbing Lu
Cone-beam X-ray luminescence computed tomography (CB-XLCT) has been proposed as a new molecular imaging modality recently. It can obtain both anatomical and functional tomographic images of an object efficiently, with the excitation of nanophosphors in vivo or in vitro by cone-beam X-rays. However, the ill-posedness of the CB-XLCT inverse problem degrades the image quality and makes it difficult to resolve adjacent luminescent targets with different concentrations, which is essential in the monitoring of nanoparticle metabolism and drug delivery...
September 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/29026680/all-optical-photoacoustic-projection-imaging
#5
Johannes Bauer-Marschallinger, Karoline Felbermayer, Thomas Berer
We introduce all-optical photoacoustic projection imaging. An array of fiber-optic interferometers is used to measure photoacoustic signals. The obtained images represent the projection of the three-dimensional spatial light absorbance within a sample onto a two-dimensional plane. We assess the performance of the system by phantom measurements and show that the fiber-optic detectors achieve a noise-equivalent pressure of 24 Pascal at a 10 MHz bandwidth. Furthermore, we demonstrate the ability to acquire high-resolution projection images of large volumes within a short period of time...
September 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/29026679/sidespim-selective-plane-illumination-based-on-a-conventional-inverted-microscope
#6
Per Niklas Hedde, Leonel Malacrida, Siavash Ahrar, Albert Siryaporn, Enrico Gratton
Previously described selective plane illumination microscopy techniques typically offset ease of use and sample handling for maximum imaging performance or vice versa. Also, to reduce cost and complexity while maximizing flexibility, it is highly desirable to implement light sheet microscopy such that it can be added to a standard research microscope instead of setting up a dedicated system. We devised a new approach termed sideSPIM that provides uncompromised imaging performance and easy sample handling while, at the same time, offering new applications of plane illumination towards fluidics and high throughput 3D imaging of multiple specimen...
September 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/29026678/statistical-model-for-oct-image-denoising
#7
Muxingzi Li, Ramzi Idoughi, Biswarup Choudhury, Wolfgang Heidrich
Optical coherence tomography (OCT) is a non-invasive technique with a large array of applications in clinical imaging and biological tissue visualization. However, the presence of speckle noise affects the analysis of OCT images and their diagnostic utility. In this article, we introduce a new OCT denoising algorithm. The proposed method is founded on a numerical optimization framework based on maximum-a-posteriori estimate of the noise-free OCT image. It combines a novel speckle noise model, derived from local statistics of empirical spectral domain OCT (SD-OCT) data, with a Huber variant of total variation regularization for edge preservation...
September 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/28966865/extended-depth-of-focus-intraocular-lens-chromatic-performance
#8
Maria S Millán, Fidel Vega
We describe a first-and-second-diffractive-order intraocular lens ((1(st),2(nd))DIOL) within the class of hybrid refractive-diffractive designs for intraocular lenses (IOLs) and analyse its properties of focus extension and compensation of longitudinal chromatic aberration (LCA), particularly for lenses with low addition. Power, energy efficiency and their wavelength dependence are extended from monofocal IOL and conventional bifocal zeroth-and-first-diffractive-order IOL ((0(th),1(st))DIOL) to (1(st),2(nd))DIOL of low addition...
September 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/28966864/accelerating-nonlinear-reconstruction-in-laminar-optical-tomography-by-use-of-recursive-svd-inversion
#9
Mengyu Jia, Jingying Jiang, Wenjuan Ma, Chenxi Li, Shuang Wang, Huijuan Zhao, Feng Gao
Image reconstruction in the most model-based biophotonic imaging modalities essentially poses an ill-posed nonlinear inverse problem, which has been effectively tackled in the diffusion-approximation-satisfied scenarios such as diffuse optical tomography. Nevertheless, a nonlinear implementation in high-resolution laminar optical tomography (LOT) is normally computationally-costly due to its strong dependency on a dense source-detector configuration and a physically-rigorous photon-transport model. To circumvent the adversity, we herein propose a practical nonlinear LOT approach to the absorption reconstruction...
September 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/28966863/three-dimensional-continuous-max-flow-optimization-based-serous-retinal-detachment-segmentation-in-sd-oct-for-central-serous-chorioretinopathy
#10
Menglin Wu, Wen Fan, Qiang Chen, Zhenlong Du, Xiaoli Li, Songtao Yuan, Hyunjin Park
Assessment of serous retinal detachment plays an important role in the diagnosis of central serous chorioretinopathy (CSC). In this paper, we propose an automatic, three-dimensional segmentation method to detect both neurosensory retinal detachment (NRD) and pigment epithelial detachment (PED) in spectral domain optical coherence tomography (SD-OCT) images. The proposed method involves constructing a probability map from training samples using random forest classification. The probability map is constructed from a linear combination of structural texture, intensity, and layer thickness information...
September 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/28966862/quantification-of-collagen-organization-in-histopathology-samples-using-liquid-crystal-based-polarization-microscopy
#11
Adib Keikhosravi, Yuming Liu, Cole Drifka, Kaitlin M Woo, Amitabh Verma, Rudolf Oldenbourg, Kevin W Eliceiri
A number of histopathology studies have utilized the label free microscopy method of Second Harmonic Generation (SHG) to investigate collagen organization in disease onset and progression. Here we explored an alternative label free imaging approach, LC-PolScope that is based on liquid crystal based polarized light imaging. We demonstrated that this more accessible technology has the ability to visualize all fibers of interest and has a good to excellent correlation between SHG and LC-PolScope measurements in fibrillar collagen orientation and alignment...
September 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/28966861/hyperspectral-imaging-with-laser-scanning-sum-frequency-generation-microscopy
#12
Adam Hanninen, Ming Wai Shu, Eric O Potma
Vibrationally sensitive sum-frequency generation (SFG) microscopy is a chemically selective imaging technique sensitive to non-centrosymmetric molecular arrangements in biological samples. The routine use of SFG microscopy has been hampered by the difficulty of integrating the required mid-infrared excitation light into a conventional, laser-scanning nonlinear optical (NLO) microscope. In this work, we describe minor modifications to a regular laser-scanning microscope to accommodate SFG microscopy as an imaging modality...
September 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/28966860/collagen-quantification-in-breast-tissue-using-a-12-wavelength-near-infrared-spectral-tomography-nirst-system
#13
Yan Zhao, William R Burger, Mingwei Zhou, Erica B Bernhardt, Peter A Kaufman, Roshani R Patel, Christina V Angeles, Brian W Pogue, Keith D Paulsen, Shudong Jiang
A portable near infrared spectral tomography (NIRST) system was adapted for breast cancer detection and treatment monitoring with improved speed of acquisition for parallel 12 wavelengths of parallel frequency-domain (FD) and continuous-wavelength (CW) measurement. Using a novel gain adjustment scheme in the Photomultiplier Tube detectors (PMTs), the data acquisition time for simultaneous acquisition involving three FD and three CW wavelengths, has been reduced from 90 to 55 seconds, while signal variation was also reduced from 2...
September 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/28966859/computer-aided-classification-of-sickle-cell-retinopathy-using-quantitative-features-in-optical-coherence-tomography-angiography
#14
Minhaj Alam, Damber Thapa, Jennifer I Lim, Dingcai Cao, Xincheng Yao
As a new optical coherence tomography (OCT) imaging modality, there is no standardized quantitative interpretation of OCT angiography (OCTA) characteristics of sickle cell retinopathy (SCR). This study is to demonstrate computer-aided SCR classification using quantitative OCTA features, i.e., blood vessel tortuosity (BVT), blood vessel diameter (BVD), vessel perimeter index (VPI), foveal avascular zone (FAZ) area, FAZ contour irregularity, parafoveal avascular density (PAD). It was observed that combined features show improved classification performance, compared to single feature...
September 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/28966858/effect-of-red-light-on-optically-trapped-spermatozoa
#15
Kay W Chow, Daryl Preece, Michael W Berns
Successful artificial insemination relies on the use of high quality spermatozoa. One measure of sperm quality is swimming force. Increased swimming force has been correlated with higher sperm swimming speeds and improved reproductive success. It is hypothesized that by increasing sperm swimming speed, one can increase swimming force. Previous studies have shown that red light irradiation causes an increase in sperm swimming speed. In the current study, 633nm red light irradiation is shown to increase mean squared displacement in trapped sperm...
September 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/28966857/cube-parametric-modeling-of-3d-foveal-shape-using-cubic-b%C3%A3-zier
#16
Sunil Kumar Yadav, Seyedamirhosein Motamedi, Timm Oberwahrenbrock, Frederike Cosima Oertel, Konrad Polthier, Friedemann Paul, Ella Maria Kadas, Alexander U Brandt
Optical coherence tomography (OCT) allows three-dimensional (3D) imaging of the retina, and is commonly used for assessing pathological changes of fovea and macula in many diseases. Many neuroinflammatory conditions are known to cause modifications to the fovea shape. In this paper, we propose a method for parametric modeling of the foveal shape. Our method exploits invariant features of the macula from OCT data and applies a cubic Bézier polynomial along with a least square optimization to produce a best fit parametric model of the fovea...
September 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/28966856/crystalline-lens-paradoxes-revisited-significance-of-age-related-restructuring-of-the-grin
#17
Conor J Sheil, Alexander V Goncharov
The accommodating volume-constant age-dependent optical (AVOCADO) model of the crystalline lens is used to explore the age-related changes in ocular power and spherical aberration. The additional parameter m in the GRIN lens model allows decoupling of the axial and radial GRIN profiles, and is used to stabilise the age-related change in ocular power. Data for age-related changes in ocular geometry and lens parameter P in the axial GRIN profile were taken from published experimental data. In our age-dependent eye model, the ocular refractive power shows behaviour similar to the previously unexplained "lens paradox"...
September 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/28966855/multi-mhz-laser-scanning-single-cell-fluorescence-microscopy-by-spatiotemporally-encoded-virtual-source-array
#18
Jianglai Wu, Anson H L Tang, Aaron T Y Mok, Wenwei Yan, Godfrey C F Chan, Kenneth K Y Wong, Kevin K Tsia
Apart from the spatial resolution enhancement, scaling of temporal resolution, equivalently the imaging throughput, of fluorescence microscopy is of equal importance in advancing cell biology and clinical diagnostics. Yet, this attribute has mostly been overlooked because of the inherent speed limitation of existing imaging strategies. To address the challenge, we employ an all-optical laser-scanning mechanism, enabled by an array of reconfigurable spatiotemporally-encoded virtual sources, to demonstrate ultrafast fluorescence microscopy at line-scan rate as high as 8 MHz...
September 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/28966854/retinal-imaging-in-human-autopsy-eyes-using-a-custom-optical-coherence-tomography-periscope
#19
Ryan P McNabb, James Tian, Sina Farsiu, Joseph A Izatt, Eleonora M Lad, Anthony N Kuo
Age-related macular degeneration (AMD) is a major cause of vision loss in the elderly. To better study the pathobiology of AMD, postmortem eyes offer an excellent opportunity to correlate optical coherence tomography (OCT) imaging characteristics with histopathology. However, postmortem eyes from autopsy present challenges to standard OCT imaging including opaque anterior segment structures and standard of care autopsy processing resulting in oblique views to the macula. To overcome these challenges, we report a custom periscope attached by a standard mount to an OCT sample arm and demonstrate high quality macular OCT acquisitions in autopsy-processed eyes...
September 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/28966853/in-vivo-imaging-of-the-palisades-of-vogt-and-the-limbal-crypts-with-sub-micrometer-axial-resolution-optical-coherence-tomography
#20
Kostadinka Bizheva, Bingyao Tan, Benjamin MacLellan, Zohreh Hosseinaee, Erik Mason, Denise Hileeto, Luigina Sorbara
A research-grade OCT system was used to image in-vivo and without contact with the tissue, the cellular structure and microvasculature of the healthy human corneo-scleral limbus. The OCT system provided 0.95 µm axial and 4 µm (2 µm) lateral resolution in biological tissue depending on the magnification of the imaging objective. Cross-sectional OCT images acquired tangentially from the inferior limbus showed reflective, loop-like features that correspond to the fibrous folds of the palisades of Vogt (POV)...
September 1, 2017: Biomedical Optics Express
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