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Biomedical Optics Express

Neha Bajwa, Joshua Au, Reza Jarrahy, Shijun Sung, Michael C Fishbein, David Riopelle, Daniel B Ennis, Tara Aghaloo, Maie A St John, Warren S Grundfest, Zachary D Taylor
Accurate and early prediction of tissue viability is the most significant determinant of tissue flap survival in reconstructive surgery. Perturbation in tissue water content (TWC) is a generic component of the tissue response to such surgeries, and, therefore, may be an important diagnostic target for assessing the extent of flap viability in vivo. We have previously shown that reflective terahertz (THz) imaging, a non-ionizing technique, can generate spatially resolved maps of TWC in superficial soft tissues, such as cornea and wounds, on the order of minutes...
January 1, 2017: Biomedical Optics Express
Ahmed Abumazwed, Wakana Kubo, Chen Shen, Takuo Tanaka, Andrew G Kirk
This paper presents a simple and accurate method (the projection method) to improve the signal to noise ratio of localized surface plasmon resonance (LSPR). The nanostructures presented in the paper can be readily fabricated by nanoimprint lithography. The finite difference time domain method is used to simulate the structures and generate a reference matrix for the method. The results are validated against experimental data and the proposed method is compared against several other recently published signal processing techniques...
January 1, 2017: Biomedical Optics Express
Peng Miao, Lingke Zhang, Miao Li, Yiguang Zhang, Shihan Feng, Qihong Wang, Nitish V Thakor
Chronically monitoring cerebral activities in awake and freely moving status is very important in physiological and pathological studies. We present a novel standalone micro-imager for monitoring the cerebral blood flow (CBF) and total hemoglobin (HbT) activities in freely moving animals using the laser speckle contrast imaging (LSCI) and optical intrinsic signal (OIS) methods. A new cranial window method, using contact lens and wide field optics, is also proposed to achieve the chronic and wide-field imaging of rat's cerebral cortex...
January 1, 2017: Biomedical Optics Express
Jingjiang Xu, Shaozhen Song, Wei Wei, Ruikang K Wang
Wide-field vascular visualization in bulk tissue that is of uneven surface is challenging due to the relatively short ranging distance and significant sensitivity fall-off for most current optical coherence tomography angiography (OCTA) systems. We report a long ranging and ultra-wide-field OCTA (UW-OCTA) system based on an akinetic swept laser. The narrow instantaneous linewidth of the swept source with its high phase stability, combined with high-speed detection in the system enable us to achieve long ranging (up to 46 mm) and almost negligible system sensitivity fall-off...
January 1, 2017: Biomedical Optics Express
Shang Wang, Monica D Garcia, Andrew L Lopez, Paul A Overbeek, Kirill V Larin, Irina V Larina
Neural tube closure is a critical feature of central nervous system morphogenesis during embryonic development. Failure of this process leads to neural tube defects, one of the most common forms of human congenital defects. Although molecular and genetic studies in model organisms have provided insights into the genes and proteins that are required for normal neural tube development, complications associated with live imaging of neural tube closure in mammals limit efficient morphological analyses. Here, we report the use of optical coherence tomography (OCT) for dynamic imaging and quantitative assessment of cranial neural tube closure in live mouse embryos in culture...
January 1, 2017: Biomedical Optics Express
I G Mbomson, S Tabor, B Lahiri, G Sharp, S G McMeekin, R M De La Rue, N P Johnson
In this paper we report on a very sensitive biosensor based on gold asymmetric nanoantennas that are capable of enhancing the molecular resonances of C-H bonds. The nanoantennas are arranged as arrays of asymmetric-split H-shape (ASH) structures, tuned to produce plasmonic resonances with reflectance double peaks within the mid-infrared vibrational resonances of C-H bonds for the assay of deposited films of the molecule 17β-estradiol (E2), used as an analyte. Measurements and numerical simulations of the reflectance spectra have enabled an estimated enhancement factor on the order of 10(5) to be obtained for a thin film of E2 on the ASH array...
January 1, 2017: Biomedical Optics Express
Huadong Song, Ying Liu, Bin Zhang, Kangzhen Tian, Panpan Zhu, Hao Lu, Qi Tang
The elasticity of red cell membrane is a critical physiological index for the activity of RBC. Study of the inherent mechanism for RBCs membrane elasticity transformation is attention-getting all along. This paper proposes an optimized measurement method of erythrocytes membrane shear modulus incorporating acousto-optic deflector (AOD) scanning optical tweezers system. By use of this method, both membrane shear moduli and sizes of RBCs with different in vitro times were determined. The experimental results reveal that the RBCs membrane elasticity and size decline with in vitro time extension...
January 1, 2017: Biomedical Optics Express
Amad Zafar, Keum-Shik Hong
In this paper, the use of initial dips using functional near-infrared spectroscopy (fNIRS) for brain-computer interface (BCI) is investigated. Features and window sizes for detecting initial dips are also discussed. Three mental tasks including mental arithmetic, mental counting, and puzzle solving are performed in obtaining fNIRS signals from the prefrontal cortex. Vector-based phase analysis method combined with a threshold circle, as a decision criterion, are used to detect the initial dips. Eight healthy subjects participate in experiment...
January 1, 2017: Biomedical Optics Express
Manmohan Singh, Jiasong Li, Zhaolong Han, Raksha Raghunathan, Achuth Nair, Chen Wu, Chih-Hao Liu, Salavat Aglyamov, Michael D Twa, Kirill V Larin
In this work we utilize optical coherence elastography (OCE) to assess the effects of UV-A/riboflavin corneal collagen crosslinking (CXL) on the mechanical anisotropy of in situ porcine corneas at various intraocular pressures (IOP). There was a distinct meridian of increased Young's modulus in all samples, and the mechanical anisotropy increased as a function of IOP and also after CXL. The presented noncontact OCE technique was able to quantify the Young's modulus and elastic anisotropy of the cornea and their changes as a function of IOP and CXL, opening new avenues of research for evaluating the effects of CXL on corneal biomechanical properties...
January 1, 2017: Biomedical Optics Express
Paritosh Pande, Ryan L Shelton, Guillermo L Monroy, Ryan M Nolan, Stephen A Boppart
We report on the development of a low-cost hand-held low-coherence interferometric imaging system based on the principle of linear optical coherence tomography (Linear OCT), a technique which was first proposed in the early 2000s as a simpler alternative to the conventional time-domain and Fourier-domain OCT. A bench-top implementation of the proposed technique is first presented and validated. The axial resolution, SNR, and sensitivity roll-of of the system was estimated to be 5.2 μm and 80 dB, and 3.7 dB over a depth of 0...
January 1, 2017: Biomedical Optics Express
Shau Poh Chong, Marcel Bernucci, Harsha Radhakrishnan, Vivek J Srinivasan
The design of a multi-functional fiber-based Optical Coherence Tomography (OCT) system for human retinal imaging with < 2 micron axial resolution in tissue is described. A detailed noise characterization of two supercontinuum light sources with different pulse repetition rates is presented. The higher repetition rate and lower noise source is found to enable a sensitivity of 96 dB with 0.15 mW light power at the cornea and a 98 microsecond exposure time. Using a broadband (560 ± 50 nm), 90/10, fused single-mode fiber coupler designed for visible wavelengths, the sample arm is integrated into an ophthalmoscope platform, similar to current clinical OCT systems...
January 1, 2017: Biomedical Optics Express
Robert D Niederriter, Baris N Ozbay, Gregory L Futia, Emily A Gibson, Juliet T Gopinath
We demonstrate a compact, pulsed diode laser source suitable for multiphoton microscopy of biological samples. The center wavelength is 976 nm, near the peak of the two-photon cross section of common fluorescent markers such as genetically encoded green and yellow fluorescent proteins. The laser repetition rate is electrically tunable between 66.67 kHz and 10 MHz, with 2.3 ps pulse duration and peak powers >1 kW. The laser components are fiber-coupled and scalable to a compact package. We demonstrate >600 μm depth penetration in brain tissue, limited by laser power...
January 1, 2017: Biomedical Optics Express
Stanislava Fialová, Marco Augustin, Corinna Fischak, Leopold Schmetterer, Stephan Handschuh, Martin Glösmann, Michael Pircher, Christoph K Hitzenberger, Bernhard Baumann
Polarization sensitive optical coherence tomography (PS-OCT) operating at 840 nm with axial resolution of 3.8 µm in tissue was used for investigating the posterior rat eye during an acute intraocular pressure (IOP) increase experiment. IOP was elevated in the eyes of anesthetized Sprague Dawley rats by cannulation of the anterior chamber. Three dimensional PS-OCT data sets were acquired at IOP levels between 14 mmHg and 105 mmHg. Maps of scleral birefringence, retinal nerve fiber layer (RNFL) retardation and relative RNFL/retina reflectivity were generated in the peripapillary area and quantitatively analyzed...
January 1, 2017: Biomedical Optics Express
Jorge Oliveira, Sérgio Pereira, Luís Gonçalves, Manuel Ferreira, Carlos A Silva
In age-related macular degeneration (AMD), the quantification of drusen is important because it is correlated with the evolution of the disease to an advanced stage. Therefore, we propose an algorithm based on a multi-surface framework for the segmentation of the limiting boundaries of drusen: the inner boundary of the retinal pigment epithelium + drusen complex (IRPEDC) and the Bruch's membrane (BM). Several segmentation methods have been considerably successful in segmenting retinal layers of healthy retinas in optical coherence tomography (OCT) images...
January 1, 2017: Biomedical Optics Express
Mariia Borovkova, Maria Serebriakova, Viacheslav Fedorov, Egor Sedykh, Vladimir Vaks, Alexander Lichutin, Alina Salnikova, Mikhail Khodzitsky
We studied an influence of continuous terahertz (THz) radiation (0.12 - 0.18 THz, average power density of 3.2 mW/cm(2)) on a rat glial cell line. A dose-dependent cytotoxic effect of THz radiation is demonstrated. After 1 minute of THz radiation exposure a relative number of apoptotic cells increased in 1.5 times, after 3 minutes it doubled. This result confirms the concept of biological hazard of intense THz radiation. Diagnostic applications of THz radiation can be restricted by the radiation power density and exposure time...
January 1, 2017: Biomedical Optics Express
Noah Bedard, Timothy Shope, Alejandro Hoberman, Mary Ann Haralam, Nader Shaikh, Jelena Kovačević, Nikhil Balram, Ivana Tošić
We present a light field digital otoscope designed to measure three-dimensional shape of the tympanic membrane. This paper describes the optical and anatomical considerations we used to develop the prototype, along with the simulation and experimental measurements of vignetting, field curvature, and lateral resolution. Using an experimental evaluation procedure, we have determined depth accuracy and depth precision of our system to be 0.05-0.07 mm and 0.21-0.44 mm, respectively. To demonstrate the application of our light field otoscope, we present the first three-dimensional reconstructions of tympanic membranes in normal and otitis media conditions, acquired from children who participated in a feasibility study at the Children's Hospital of Pittsburgh of the University of Pittsburgh Medical Center...
January 1, 2017: Biomedical Optics Express
D Choudhury, M G Tanner, S McAughtrie, F Yu, B Mills, T R Choudhary, S Seth, T H Craven, J M Stone, I K Mati, C J Campbell, M Bradley, C K I Williams, K Dhaliwal, T A Birks, R R Thomson
Previously unobtainable measurements of alveolar pH were obtained using an endoscope-deployable optrode. The pH sensing was achieved using functionalized gold nanoshell sensors and surface enhanced Raman spectroscopy (SERS). The optrode consisted of an asymmetric dual-core optical fiber designed for spatially separating the optical pump delivery and signal collection, in order to circumvent the unwanted Raman signal generated within the fiber. Using this approach, we demonstrate a ~100-fold increase in SERS signal-to-fiber background ratio, and demonstrate multiple site pH sensing with a measurement accuracy of ± 0...
January 1, 2017: Biomedical Optics Express
David S Jung, John A Crowe, John P Birchall, Michael G Somekh, Chung W See
To improve the diagnostic prediction of recurrence of otitis media with effusion after surgery, an anti-confocal system combined with spectroscopic measurements is proposed to reject unwanted signals from the eardrum and assess the blood content. The anti-confocal system was experimentally evaluated on both optical middle ear phantom and human skin. Results showed effective rejection of signals from the eardrum using a central stop replacing the confocal pinhole, while still detecting signals from the middle ear mucosa...
January 1, 2017: Biomedical Optics Express
Ting Li, Yaoxian Li, Yu Lin, Kai Li
Cupping therapy has been used in traditional Chinese medicine for thousands of years to relieve muscle pain/tendency/fatigue and to cure or reduce symbols of other diseases. However, its therapeutic effect is sparsely interpreted in the language of modern physiology. To objectively evaluate its therapeutic effect, we focused on dry cupping treatment and utilized near-infrared spectroscopy (NIRS) to assess the concentration change in oxy-hemoglobin ([HbO2]), deoxy-hemoglobin ([Hb]), and blood volume in the course of cupping therapy over 13 volunteers on the infraspinatus muscle, where is usually applied for shoulder pains...
January 1, 2017: Biomedical Optics Express
Matthias Salas, Marco Augustin, Laurin Ginner, Abhishek Kumar, Bernhard Baumann, Rainer Leitgeb, Wolfgang Drexler, Sonja Prager, Julia Hafner, Ursula Schmidt-Erfurth, Michael Pircher
The purpose of this work is to investigate the benefits of adaptive optics (AO) technology for optical coherence tomography angiography (OCTA). OCTA has shown great potential in non-invasively enhancing the contrast of vessels and small capillaries. Especially the capability of the technique to visualize capillaries with a lateral extension that is below the transverse resolution of the system opens unique opportunities in diagnosing retinal vascular diseases. However, there are some limitations of this technology such as shadowing and projection artifacts caused by overlying vasculature or the inability to determine the true extension of a vessel...
January 1, 2017: Biomedical Optics Express
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