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Biomedical Optics Express

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https://www.readbyqxmd.com/read/29188125/direct-inversion-algorithm-for-focal-plane-scanning-optical-projection-tomography
#1
Kevin G Chan, Michael Liebling
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...
November 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/29188124/measuring-blood-oxygen-saturation-along-a-capillary-vessel-in-human
#2
Kfir Akons, Eldad J Dann, Dvir Yelin
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...
November 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/29188123/dynamics-of-the-human-brain-network-revealed-by-time-frequency-effective-connectivity-in-fnirs
#3
Grégoire Vergotte, Kjerstin Torre, Venkata Chaitanya Chirumamilla, Abdul Rauf Anwar, Sergiu Groppa, Stéphane Perrey, Muthuraman Muthuraman
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...
November 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/29188122/time-domain-diffuse-correlation-spectroscopy-with-a-high-coherence-pulsed-source-in-vivo-and-phantom-results
#4
M Pagliazzi, S Konugolu Venkata Sekar, L Colombo, E Martinenghi, J Minnema, R Erdmann, D Contini, A Dalla Mora, A Torricelli, A Pifferi, T Durduran
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. However, while TRS provides a path length resolved data, the standard DCS does not. Recently, a time domain DCS experiment showed path length resolved measurements for improved quantification with respect to classical DCS, but was limited to phantoms and small animal studies...
November 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/29188121/statistical-independence-in-nonlinear-model-based-inversion-for-quantitative-photoacoustic-tomography
#5
Lu An, Teedah Saratoon, Martina Fonseca, Robert Ellwood, Ben Cox
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. A gradient-based optimisation algorithm is used to minimise the error functional, which includes a term representing the mutual information between the chromophores in addition to the standard least-squares data error...
November 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/29188120/data-driven-imaging-of-tissue-inflammation-using-rgb-based-hyperspectral-reconstruction-toward-personal-monitoring-of-dermatologic-health
#6
Taehoon Kim, Michelle A Visbal-Onufrak, Raymond L Konger, Young L Kim
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...
November 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/29188119/multi-shaping-technique-reduces-sidelobe-magnitude-in-optical-coherence-tomography
#7
Yu Chen, Jeff Fingler, Scott E Fraser
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...
November 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/29188118/common-path-phase-sensitive-optical-coherence-tomography-provides-enhanced-phase-stability-and-detection-sensitivity-for-dynamic-elastography
#8
Gongpu Lan, Manmohan Singh, Kirill V Larin, Michael D Twa
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 (0.24 ± 0.07nm) than conventional PhS-OCE (1.60 ± 0.11μm). The coefficient of variation for surface displacement measurements using conventional PhS-OCE averaged 11% versus 2% for common-path PhS-OCE...
November 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/29188117/efficiency-enhancement-of-raman-spectroscopy-at-long-working-distance-by-parabolic-reflector
#9
Yao Tian, Joshua Weiming Su, Jian Ju, Quan Liu
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. To achieve a high signal level, usually a high numerical aperture objective is employed. One drawback with these objectives is that their working distance is very short. However, in many cases of clinical diagnostics, a long working distance is preferable...
November 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/29188116/multimodal-nonlinear-optical-imaging-of-unstained-retinas-in-the-epi-direction-with-a-sub-40-fs-yb-fiber-laser
#10
Gabrielle A Murashova, Christopher A Mancuso, Jacob L Canfield, Sanae Sakami, Krzysztof Palczewski, Grazyna Palczewska, Marcos Dantus
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...
November 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/29188115/raman-spectral-post-processing-for-oral-tissue-discrimination-a-step-for-an-automatized-diagnostic-system
#11
Luis Felipe C S Carvalho, Marcelo Saito Nogueira, Lázaro P M Neto, Tanmoy T Bhattacharjee, Airton A Martin
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. Hence, this study aims to evaluate the performance of preprocessing steps and multivariate analysis methods for the classification of normal tissues and pathological oral lesion spectra...
November 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/29188114/optical-surface-plasmon-resonance-sensor-modified-by-mutant-glucose-galactose-binding-protein-for-affinity-detection-of-glucose-molecules
#12
Dachao Li, Jie Su, Jia Yang, Songlin Yu, Jingxin Zhang, Kexin Xu, Haixia Yu
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. In this paper, an optical surface plasmon resonance (SPR) sensor modified by the glucose/galactose-binding (GGB) protein which has good affinity to glucose molecules was presented for specific and sensitive glucose detection...
November 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/29188113/label-free-fiber-optic-optrode-for-the-detection-of-class-c-%C3%AE-lactamases-expressed-by-drug-resistant-bacteria
#13
Simona Zuppolini, Giuseppe Quero, Marco Consales, Laura Diodato, Patrizio Vaiano, Alberto Venturelli, Matteo Santucci, Francesca Spyrakis, Maria P Costi, Michele Giordano, Antonello Cutolo, Andrea Cusano, Anna Borriello
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...
November 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/29188112/multimode-fibre-based-imaging-for-optically-cleared-samples
#14
Ivan Gusachenko, Jonathan Nylk, Javier A Tello, Kishan Dholakia
Optical clearing is emerging as a popular approach particularly for studies in neuroscience. However the use of corrosive clearing solutions typically requires sophisticated objectives or extreme care with optical components chosen for single- or multi-photon imaging. In contrast to the use of complex, custom-made microscope objectives, we show that the use of a corrected multimode fibre (MMF) offers a route that is resistant to corrosion, can be used in clearing media, is not constrained by the refractive index of the immersion medium and offers flexible working distances...
November 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/29188111/automatic-detection-of-the-foveal-center-in-optical-coherence-tomography
#15
Bart Liefers, Freerk G Venhuizen, Vivian Schreur, Bram van Ginneken, Carel Hoyng, Sascha Fauser, Thomas Theelen, Clara I Sánchez
We propose a method for automatic detection of the foveal center in optical coherence tomography (OCT). The method is based on a pixel-wise classification of all pixels in an OCT volume using a fully convolutional neural network (CNN) with dilated convolution filters. The CNN-architecture contains anisotropic dilated filters and a shortcut connection and has been trained using a dynamic training procedure where the network identifies its own relevant training samples. The performance of the proposed method is evaluated on a data set of 400 OCT scans of patients affected by age-related macular degeneration (AMD) at different severity levels...
November 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/29188110/optimal-hemoglobin-extinction-coefficient-data-set-for-near-infrared-spectroscopy
#16
Yue Zhao, Lina Qiu, Yunlong Sun, Chong Huang, Ting Li
Extinction coefficient (ε) is a critical parameter for quantification of oxy-, deoxy-, and total-hemoglobin concentrations (Δ[HbO2], Δ[Hb], Δ[tHb]) from optical measurements of Near-infrared spectroscopy (NIRS). There are several different ε data sets which were frequently used in NIRS quantification. A previous study reported that even a small variation in ε could cause a significant difference in hemodynamic measurements. Apparently the selection of an optimal ε data set is important for NIRS. We conducted oxygen-state-varied and blood-concentration-varied model experiments with 57 human blood samples to mimic tissue hemodynamic variations...
November 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/29188109/speckle-variance-oct-for-depth-resolved-assessment-of-the-viability-of-bovine-embryos
#17
S Caujolle, R Cernat, G Silvestri, M J Marques, A Bradu, T Feuchter, G Robinson, D K Griffin, A Podoleanu
The morphology of embryos produced by in vitro fertilization (IVF) is commonly used to estimate their viability. However, imaging by standard microscopy is subjective and unable to assess the embryo on a cellular scale after compaction. Optical coherence tomography is an imaging technique that can produce a depth-resolved profile of a sample and can be coupled with speckle variance (SV) to detect motion on a micron scale. In this study, day 7 post-IVF bovine embryos were observed either short-term (10 minutes) or long-term (over 18 hours) and analyzed by swept source OCT and SV to resolve their depth profile and characterize micron-scale movements potentially associated with viability...
November 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/29188108/ultrahigh-resolution-optical-coherence-elastography-through-a-micro-endoscope-towards-in-vivo-imaging-of-cellular-scale-mechanics
#18
Qi Fang, Andrea Curatolo, Philip Wijesinghe, Yen Ling Yeow, Juliana Hamzah, Peter B Noble, Karol Karnowski, David D Sampson, Ruth Ganss, Jun Ki Kim, Woei M Lee, Brendan F Kennedy
In this paper, we describe a technique capable of visualizing mechanical properties at the cellular scale deep in living tissue, by incorporating a gradient-index (GRIN)-lens micro-endoscope into an ultrahigh-resolution optical coherence elastography system. The optical system, after the endoscope, has a lateral resolution of 1.6 µm and an axial resolution of 2.2 µm. Bessel beam illumination and Gaussian mode detection are used to provide an extended depth-of-field of 80 µm, which is a 4-fold improvement over a fully Gaussian beam case with the same lateral resolution...
November 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/29188107/real-time-endoscopic-optical-properties-imaging
#19
Joseph P Angelo, Martijn van de Giessen, Sylvain Gioux
With almost 50% of all surgeries in the U.S. being performed as minimally invasive procedures, there is a need to develop quantitative endoscopic imaging techniques to aid surgical guidance. Recent developments in widefield optical imaging make endoscopic implementations of real-time measurement possible. In this work, we introduce a proof-of-concept endoscopic implementation of a functional widefield imaging technique called 3D single snapshot of optical properties (3D-SSOP) that provides quantitative maps of absorption and reduced scattering optical properties as well as surface topography with simple instrumentation added to a commercial endoscope...
November 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/29188106/non-invasive-assessment-of-human-cone-photoreceptor-function
#20
Robert F Cooper, William S Tuten, Alfredo Dubra, David H Brainard, Jessica I W Morgan
Vision begins when light isomerizes the photopigments within photoreceptors. Noninvasive cellular-scale observation of the structure of the human photoreceptor mosaic is made possible through the use of adaptive optics (AO) enhanced ophthalmoscopes, but establishing noninvasive objective measures of photoreceptor function on a similar scale has been more difficult. AO ophthalmoscope images acquired with near-infrared light show that individual cone photoreceptor reflectance can change in response to a visible stimulus...
November 1, 2017: Biomedical Optics Express
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