Multiple projection optical diffusion tomography with plane wave illumination

International Nuclear Information System (INIS)

Markel, Vadim A; Schotland, John C

2005-01-01

We describe a new data collection scheme for optical diffusion tomography in which plane wave illumination is combined with multiple projections in the slab imaging geometry. Multiple projection measurements are performed by rotating the slab around the sample. The advantage of the proposed method is that the measured data are more compatible with the dynamic range of most commonly used detectors. At the same time, multiple projections improve image quality by mutually interchanging the depth and transverse directions, and the scanned (detection) and integrated (illumination) surfaces. Inversion methods are derived for image reconstructions with extremely large data sets. Numerical simulations are performed for fixed and rotated slabs

Functional imaging of small tissue volumes with diffuse optical tomography

Science.gov (United States)

Klose, Alexander D.; Hielscher, Andreas H.

2006-03-01

Imaging of dynamic changes in blood parameters, functional brain imaging, and tumor imaging are the most advanced application areas of diffuse optical tomography (DOT). When dealing with the image reconstruction problem one is faced with the fact that near-infrared photons, unlike X-rays, are highly scattered when they traverse biological tissue. Image reconstruction schemes are required that model the light propagation inside biological tissue and predict measurements on the tissue surface. By iteratively changing the tissue-parameters until the predictions agree with the real measurements, a spatial distribution of optical properties inside the tissue is found. The optical properties can be related to the tissue oxygenation, inflammation, or to the fluorophore concentration of a biochemical marker. If the model of light propagation is inaccurate, the reconstruction process will lead to an inaccurate result as well. Here, we focus on difficulties that are encountered when DOT is employed for functional imaging of small tissue volumes, for example, in cancer studies involving small animals, or human finger joints for early diagnosis of rheumatoid arthritis. Most of the currently employed image reconstruction methods rely on the diffusion theory that is an approximation to the equation of radiative transfer. But, in the cases of small tissue volumes and tissues that contain low scattering regions diffusion theory has been shown to be of limited applicability Therefore, we employ a light propagation model that is based on the equation of radiative transfer, which promises to overcome the limitations.

Pseudodynamic systems approach based on a quadratic approximation of update equations for diffuse optical tomography.

Science.gov (United States)

Biswas, Samir Kumar; Kanhirodan, Rajan; Vasu, Ram Mohan; Roy, Debasish

2011-08-01

We explore a pseudodynamic form of the quadratic parameter update equation for diffuse optical tomographic reconstruction from noisy data. A few explicit and implicit strategies for obtaining the parameter updates via a semianalytical integration of the pseudodynamic equations are proposed. Despite the ill-posedness of the inverse problem associated with diffuse optical tomography, adoption of the quadratic update scheme combined with the pseudotime integration appears not only to yield higher convergence, but also a muted sensitivity to the regularization parameters, which include the pseudotime step size for integration. These observations are validated through reconstructions with both numerically generated and experimentally acquired data.

Diffuse optical tomography for breast cancer imaging guided by computed tomography: A feasibility study.

Science.gov (United States)

Baikejiang, Reheman; Zhang, Wei; Li, Changqing

2017-01-01

Diffuse optical tomography (DOT) has attracted attentions in the last two decades due to its intrinsic sensitivity in imaging chromophores of tissues such as hemoglobin, water, and lipid. However, DOT has not been clinically accepted yet due to its low spatial resolution caused by strong optical scattering in tissues. Structural guidance provided by an anatomical imaging modality enhances the DOT imaging substantially. Here, we propose a computed tomography (CT) guided multispectral DOT imaging system for breast cancer imaging. To validate its feasibility, we have built a prototype DOT imaging system which consists of a laser at the wavelength of 650 nm and an electron multiplying charge coupled device (EMCCD) camera. We have validated the CT guided DOT reconstruction algorithms with numerical simulations and phantom experiments, in which different imaging setup parameters, such as projection number of measurements and width of measurement patch, have been investigated. Our results indicate that an air-cooling EMCCD camera is good enough for the transmission mode DOT imaging. We have also found that measurements at six angular projections are sufficient for DOT to reconstruct the optical targets with 2 and 4 times absorption contrast when the CT guidance is applied. Finally, we have described our future research plan on integration of a multispectral DOT imaging system into a breast CT scanner.

Functional imaging of the human brain using a modular, fibre-less, high-density diffuse optical tomography system.

Science.gov (United States)

Chitnis, Danial; Cooper, Robert J; Dempsey, Laura; Powell, Samuel; Quaggia, Simone; Highton, David; Elwell, Clare; Hebden, Jeremy C; Everdell, Nicholas L

2016-10-01

We present the first three-dimensional, functional images of the human brain to be obtained using a fibre-less, high-density diffuse optical tomography system. Our technology consists of independent, miniaturized, silicone-encapsulated DOT modules that can be placed directly on the scalp. Four of these modules were arranged to provide up to 128, dual-wavelength measurement channels over a scalp area of approximately 60 × 65 mm 2 . Using a series of motor-cortex stimulation experiments, we demonstrate that this system can obtain high-quality, continuous-wave measurements at source-detector separations ranging from 14 to 55 mm in adults, in the presence of hair. We identify robust haemodynamic response functions in 5 out of 5 subjects, and present diffuse optical tomography images that depict functional haemodynamic responses that are well-localized in all three dimensions at both the individual and group levels. This prototype modular system paves the way for a new generation of wearable, wireless, high-density optical neuroimaging technologies.

Study of continuous-wave domain fluorescence diffuse optical tomography for quality control on agricultural produce

Energy Technology Data Exchange (ETDEWEB)

Nadhira, Vebi, E-mail: vebi@tf.itb.ac.id; Kurniadi, Deddy, E-mail: vebi@tf.itb.ac.id; Juliastuti, E., E-mail: vebi@tf.itb.ac.id; Sutiswan, Adeline, E-mail: vebi@tf.itb.ac.id [Instrumentation and Control Research Group, Faculty of Industrial Technology, Institute Technology of Bandung, Ganesha 10 40132 Bandung (Indonesia)

2014-03-24

The importance of monitoring the quality of vegetables and fruits is prosperity by giving a competitive advantage for producer and providing a more healthy food for consumer. Diffuse Optical Tomography (DOT) is offering the possibility to detect the internal defects of the agricultural produce quality. Fluorescence diffuse optical tomography (FDOT) is the development of DOT, offering the possibilities to improve spatial resolution and to contrast image. The purpose of this research is to compare FDOT and DOT in forward analysis with continuous wave approach. The scattering and absorbing parameters of potatoes are used to represent the real condition. The object was illuminated by the NIR source from some positions on the boundary of object. A set of NIR detector are placed on the peripheral position of the object to measure the intensity of propagated or emitted light. In the simulation, we varied a condition of object then we analyzed the sensitivity of forward problem. The result of this study shows that FDOT has a better sensitivity than DOT and a better potential to monitor internal defects of agricultural produce because of the contrast value between optical and fluorescence properties of agricultural produce normal tissue and defects.

Algebraic reconstruction techniques for spectral reconstruction in diffuse optical tomography

International Nuclear Information System (INIS)

Brendel, Bernhard; Ziegler, Ronny; Nielsen, Tim

2008-01-01

Reconstruction in diffuse optical tomography (DOT) necessitates solving the diffusion equation, which is nonlinear with respect to the parameters that have to be reconstructed. Currently applied solving methods are based on the linearization of the equation. For spectral three-dimensional reconstruction, the emerging equation system is too large for direct inversion, but the application of iterative methods is feasible. Computational effort and speed of convergence of these iterative methods are crucial since they determine the computation time of the reconstruction. In this paper, the iterative methods algebraic reconstruction technique (ART) and conjugated gradients (CGs) as well as a new modified ART method are investigated for spectral DOT reconstruction. The aim of the modified ART scheme is to speed up the convergence by considering the specific conditions of spectral reconstruction. As a result, it converges much faster to favorable results than conventional ART and CG methods

Preclinical, fluorescence and diffuse optical tomography: non-contact instrumentation, modeling and time-resolved 3D reconstruction

International Nuclear Information System (INIS)

Nouizi, F.

2011-09-01

Time-Resolved Diffuse Optical Tomography (TR-DOT) is a new non-invasive imaging technique increasingly used in the clinical and preclinical fields. It yields optical absorption and scattering maps of the explored organs, and related physiological parameters. Time-Resolved Fluorescence Diffuse Optical Tomography (TR-FDOT) is based on the detection of fluorescence photons. It provides spatio-temporal maps of fluorescent probe concentrations and life times, and allows access to metabolic and molecular imaging which is important for diagnosis and therapeutic monitoring, particularly in oncology. The main goal of this thesis was to reconstruct 3D TR-DOT/TR-FDOT images of small animals using time-resolved optical technology. Data were acquired using optical fibers fixed around the animal without contact with its surface. The work was achieved in four steps: 1)- Setting up an imaging device to record the 3D coordinates of an animal's surface; 2)- Modeling the no-contact approach to solve the forward problem; 3)- Processing of the measured signals taking into account the impulse response of the device; 4)- Implementation of a new image reconstruction method based on a selection of carefully chosen points. As a result, good-quality 3D optical images were obtained owing to reduced cross-talk between absorption and scattering. Moreover, the computation time was cut down, compared to full-time methods using whole temporal profiles. (author)

Functional imaging and assessment of the glucose diffusion rate in epithelial tissues in optical coherence tomography

International Nuclear Information System (INIS)

Larin, K V; Tuchin, V V

2008-01-01

Functional imaging, monitoring and quantitative description of glucose diffusion in epithelial and underlying stromal tissues in vivo and controlling of the optical properties of tissues are extremely important for many biomedical applications including the development of noninvasive or minimally invasive glucose sensors as well as for therapy and diagnostics of various diseases, such as cancer, diabetic retinopathy, and glaucoma. Recent progress in the development of a noninvasive molecular diffusion biosensor based on optical coherence tomography (OCT) is described. The diffusion of glucose was studied in several epithelial tissues both in vitro and in vivo. Because OCT provides depth-resolved imaging of tissues with high in-depth resolution, the glucose diffusion is described not only as a function of time but also as a function of depth. (special issue devoted to application of laser technologies in biophotonics and biomedical studies)

Imaging osteoarthritis in the knee joints using x-ray guided diffuse optical tomography

Science.gov (United States)

Zhang, Qizhi; Yuan, Zhen; Sobel, Eric S.; Jiang, Huabei

2010-02-01

In our previous studies, near-infrared (NIR) diffuse optical tomography (DOT) had been successfully applied to imaging osteoarthritis (OA) in the finger joints where significant difference in optical properties of the joint tissues was evident between healthy and OA finger joints. Here we report for the first time that large joints such as the knee can also be optically imaged especially when DOT is combined with x-ray tomosynthesis where the 3D image of the bones from x-ray is incorporated into the DOT reconstruction as spatial a priori structural information. This study demonstrates that NIR light can image large joints such as the knee in addition to finger joints, which will drastically broaden the clinical utility of our x-ray guided DOT technique for OA diagnosis.

Validating atlas-guided DOT: a comparison of diffuse optical tomography informed by atlas and subject-specific anatomies.

Science.gov (United States)

Cooper, Robert J; Caffini, Matteo; Dubb, Jay; Fang, Qianqian; Custo, Anna; Tsuzuki, Daisuke; Fischl, Bruce; Wells, William; Dan, Ippeita; Boas, David A

2012-09-01

We describe the validation of an anatomical brain atlas approach to the analysis of diffuse optical tomography (DOT). Using MRI data from 32 subjects, we compare the diffuse optical images of simulated cortical activation reconstructed using a registered atlas with those obtained using a subject's true anatomy. The error in localization of the simulated cortical activations when using a registered atlas is due to a combination of imperfect registration, anatomical differences between atlas and subject anatomies and the localization error associated with diffuse optical image reconstruction. When using a subject-specific MRI, any localization error is due to diffuse optical image reconstruction only. In this study we determine that using a registered anatomical brain atlas results in an average localization error of approximately 18 mm in Euclidean space. The corresponding error when the subject's own MRI is employed is 9.1 mm. In general, the cost of using atlas-guided DOT in place of subject-specific MRI-guided DOT is a doubling of the localization error. Our results show that despite this increase in error, reasonable anatomical localization is achievable even in cases where the subject-specific anatomy is unavailable. Copyright © 2012 Elsevier Inc. All rights reserved.

Diffuse Optical Tomography for Brain Imaging: Continuous Wave Instrumentation and Linear Analysis Methods

Science.gov (United States)

Giacometti, Paolo; Diamond, Solomon G.

Diffuse optical tomography (DOT) is a functional brain imaging technique that measures cerebral blood oxygenation and blood volume changes. This technique is particularly useful in human neuroimaging measurements because of the coupling between neural and hemodynamic activity in the brain. DOT is a multichannel imaging extension of near-infrared spectroscopy (NIRS). NIRS uses laser sources and light detectors on the scalp to obtain noninvasive hemodynamic measurements from spectroscopic analysis of the remitted light. This review explains how NIRS data analysis is performed using a combination of the modified Beer-Lambert law (MBLL) and the diffusion approximation to the radiative transport equation (RTE). Laser diodes, photodiode detectors, and optical terminals that contact the scalp are the main components in most NIRS systems. Placing multiple sources and detectors over the surface of the scalp allows for tomographic reconstructions that extend the individual measurements of NIRS into DOT. Mathematically arranging the DOT measurements into a linear system of equations that can be inverted provides a way to obtain tomographic reconstructions of hemodynamics in the brain.

Parallel, Rapid Diffuse Optical Tomography of Breast

National Research Council Canada - National Science Library

Yodh, Arjun

2001-01-01

During the last year we have experimentally and computationally investigated rapid acquisition and analysis of informationally dense diffuse optical data sets in the parallel plate compressed breast geometry...

Parallel, Rapid Diffuse Optical Tomography of Breast

National Research Council Canada - National Science Library

Yodh, Arjun

2002-01-01

During the last year we have experimentally and computationally investigated rapid acquisition and analysis of informationally dense diffuse optical data sets in the parallel plate compressed breast geometry...

Measurement of shear-induced diffusion of red blood cells using dynamic light scattering-optical coherence tomography

Science.gov (United States)

Tang, Jianbo; Erdener, Sefik Evren; Li, Baoqiang; Fu, Buyin; Sakadzic, Sava; Carp, Stefan A.; Lee, Jonghwan; Boas, David A.

2018-02-01

Dynamic Light Scattering-Optical Coherence Tomography (DLS-OCT) takes the advantages of using DLS to measure particle flow and diffusion within an OCT resolution-constrained 3D volume, enabling the simultaneous measurements of absolute RBC velocity and diffusion coefficient with high spatial resolution. In this work, we applied DLS-OCT to measure both RBC velocity and the shear-induced diffusion coefficient within penetrating venules of the somatosensory cortex of anesthetized mice. Blood flow laminar profile measurements indicate a blunted laminar flow profile, and the degree of blunting decreases with increasing vessel diameter. The measured shear-induced diffusion coefficient was proportional to the flow shear rate with a magnitude of 0.1 to 0.5 × 10-6 mm2 . These results provide important experimental support for the recent theoretical explanation for why DCS is dominantly sensitive to RBC diffusive motion.

A time-domain fluorescence diffusion optical tomography system for breast tumor diagnosis

Science.gov (United States)

Zhang, Wei; Gao, Feng; Wu, LinHui; Ma, Wenjuan; Yang, Fang; Zhou, Zhongxing; Zhang, Limin; Zhao, Huijuan

2011-02-01

A prototype time-domain fluorescence diffusion optical tomography (FDOT) system using near-infrared light is presented. The system employs two pulsed light sources, 32 source fibers and 32 detection channels, working separately for acquiring the temporal distribution of the photon flux on the tissue surface. The light sources are provided by low power picosecond pulsed diode lasers at wavelengths of 780 nm and 830 nm, and a 1×32-fiber-optic-switch sequentially directs light sources to the object surface through 32 source fibers. The light signals re-emitted from the object are collected by 32 detection fibers connected to four 8×1 fiber-optic-switch and then routed to four time-resolved measuring channels, each of which consists of a collimator, a filter wheel, a photomultiplier tube (PMT) photon-counting head and a time-correlated single photon counting (TCSPC) channel. The performance and efficacy of the designed multi-channel PMT-TCSPC system are assessed by reconstructing the fluorescent yield and lifetime images of a solid phantom.

Visualisation of details of a complicated inner structure of model objects by the method of diffusion optical tomography

International Nuclear Information System (INIS)

Tret'yakov, Evgeniy V; Shuvalov, Vladimir V; Shutov, I V

2002-01-01

An approximate algorithm is tested for solving the problem of diffusion optical tomography in experiments on the visualisation of details of the inner structure of strongly scattering model objects containing scattering and semitransparent inclusions, as well as absorbing inclusions located inside other optical inhomogeneities. The stability of the algorithm to errors is demonstrated, which allows its use for a rapid (2 - 3 min) image reconstruction of the details of objects with a complicated inner structure. (laser biology and medicine)

Parallel Solver for Diffuse Optical Tomography on Realistic Head Models With Scattering and Clear Regions.

Science.gov (United States)

Placati, Silvio; Guermandi, Marco; Samore, Andrea; Scarselli, Eleonora Franchi; Guerrieri, Roberto

2016-09-01

Diffuse optical tomography is an imaging technique, based on evaluation of how light propagates within the human head to obtain the functional information about the brain. Precision in reconstructing such an optical properties map is highly affected by the accuracy of the light propagation model implemented, which needs to take into account the presence of clear and scattering tissues. We present a numerical solver based on the radiosity-diffusion model, integrating the anatomical information provided by a structural MRI. The solver is designed to run on parallel heterogeneous platforms based on multiple GPUs and CPUs. We demonstrate how the solver provides a 7 times speed-up over an isotropic-scattered parallel Monte Carlo engine based on a radiative transport equation for a domain composed of 2 million voxels, along with a significant improvement in accuracy. The speed-up greatly increases for larger domains, allowing us to compute the light distribution of a full human head ( ≈ 3 million voxels) in 116 s for the platform used.

A comprehensive study of the use of temporal moments in time-resolved diffuse optical tomography: part I. Theoretical material

Energy Technology Data Exchange (ETDEWEB)

Ducros, Nicolas; Herve, Lionel; Dinten, Jean-Marc [CEA, LETI, MINATEC, 17 rue des Martyrs, F-38054 Grenoble (France); Da Silva, Anabela [Institut Fresnel, CNRS UMR 6133, Universite Aix-Marseille, Ecole Centrale Marseille, Campus universitaire de Saint-Jerome, F-13013 Marseille (France); Peyrin, Francoise [CREATIS, INSERM U 630, CNRS UMR 5220, Universite de Lyon, INSA de Lyon, bat. Blaise Pascal, F-69621 Villeurbanne Cedex (France)], E-mail: nicolas.ducros@cea.fr

2009-12-07

The problem of fluorescence diffuse optical tomography consists in localizing fluorescent markers from near-infrared light measurements. Among the different available acquisition modalities, the time-resolved modality is expected to provide measurements of richer information content. To extract this information, the moments of the time-resolved measurements are often considered. In this paper, a theoretical analysis of the moments of the forward problem in fluorescence diffuse optical tomography is proposed for the infinite medium geometry. The moments are expressed as a function of the source, detector and markers positions as well as the optical properties of the medium and markers. Here, for the first time, an analytical expression holding for any moments order is mathematically derived. In addition, analytical expressions of the mean, variance and covariance of the moments in the presence of noise are given. These expressions are used to demonstrate the increasing sensitivity of moments to noise. Finally, the newly derived expressions are illustrated by means of sensitivity maps. The physical interpretation of the analytical formulae in conjunction with their map representations could provide new insights into the analysis of the information content provided by moments.

Three-dimensional in vivo fluorescence diffuse optical tomography of breast cancer in humans

Science.gov (United States)

Corlu, Alper; Choe, Regine; Durduran, Turgut; Rosen, Mark A.; Schweiger, Martin; Arridge, Simon R.; Schnall, Mitchell D.; Yodh, Arjun G.

2007-05-01

We present three-dimensional (3D) in vivo images of human breast cancer based on fluorescence diffuse optical tomography (FDOT). To our knowledge, this work represents the first reported 3D fluorescence tomography of human breast cancer in vivo. In our protocol, the fluorophore Indocyanine Green (ICG) is injected intravenously. Fluorescence excitation and detection are accomplished in the soft-compression, parallel-plane, transmission geometry using laser sources at 786 nm and spectrally filtered CCD detection. Phantom and in vivo studies confirm the signals are due to ICG fluorescence, rather than tissue autofluorescence and excitation light leakage. Fluorescence images of breast tumors were in good agreement with those of MRI, and with DOT based on endogenous contrast. Tumorto- normal tissue contrast based on ICG fluorescence was two-to-four-fold higher than contrast based on hemoglobin and scattering parameters. In total the measurements demonstrate that FDOT of breast cancer is feasible and promising.

Shear-induced diffusion of red blood cells measured with dynamic light scattering-optical coherence tomography.

Science.gov (United States)

Tang, Jianbo; Erdener, Sefik Evren; Li, Baoqiang; Fu, Buyin; Sakadzic, Sava; Carp, Stefan A; Lee, Jonghwan; Boas, David A

2018-02-01

Quantitative measurements of intravascular microscopic dynamics, such as absolute blood flow velocity, shear stress and the diffusion coefficient of red blood cells (RBCs), are fundamental in understanding the blood flow behavior within the microcirculation, and for understanding why diffuse correlation spectroscopy (DCS) measurements of blood flow are dominantly sensitive to the diffusive motion of RBCs. Dynamic light scattering-optical coherence tomography (DLS-OCT) takes the advantages of using DLS to measure particle flow and diffusion within an OCT resolution-constrained three-dimensional volume, enabling the simultaneous measurements of absolute RBC velocity and diffusion coefficient with high spatial resolution. In this work, we applied DLS-OCT to measure both RBC velocity and the shear-induced diffusion coefficient within penetrating venules of the somatosensory cortex of anesthetized mice. Blood flow laminar profile measurements indicate a blunted laminar flow profile and the degree of blunting decreases with increasing vessel diameter. The measured shear-induced diffusion coefficient was proportional to the flow shear rate with a magnitude of ~0.1 to 0.5 × 10 -6  mm 2 . These results provide important experimental support for the recent theoretical explanation for why DCS is dominantly sensitive to RBC diffusive motion. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Highly-sensitive and large-dynamic diffuse optical tomography system for breast tumor detection

Science.gov (United States)

Du, Wenwen; Zhang, Limin; Yin, Guoyan; Zhang, Yanqi; Zhao, Huijuan; Gao, Feng

2018-02-01

Diffuse optical tomography (DOT) as a new functional imaging has important clinical applications in many aspects such as benign and malignant breast tumor detection, tumor staging and so on. For quantitative detection of breast tumor, a three-wavelength continuous-wave DOT prototype system combined the ultra-high sensitivity of the photon-counting detection and the measurement parallelism of the lock-in technique was developed to provide high temporal resolution, high sensitivity, large dynamic detection range and signal-to-noise ratio. Additionally, a CT-analogous scanning mode was proposed to cost-effectively increase the detection data. To evaluate the feasibility of the system, a series of assessments were conducted. The results demonstrate that the system can obtain high linearity, stability and negligible inter-wavelength crosstalk. The preliminary phantom experiments show the absorption coefficient is able to be successfully reconstructed, indicating that the system is one of the ideal platforms for optical breast tumor detection.

Identification of prefrontal cortex (BA10) activation while performing Stroop test using diffuse optical tomography

Science.gov (United States)

Khadka, Sabin; Chityala, Srujan R.; Tian, Fenghua; Liu, Hanli

2011-03-01

Stroop test is commonly used as a behavior-testing tool for psychological examinations that are related to attention and cognitive control of the human brain. Studies have shown activations in Broadmann area 10 (BA10) of prefrontal cortex (PFC) during attention and cognitive process. The use of diffuse optical tomography (DOT) for human brain mapping is becoming more prevalent. In this study we expect to find neural correlates between the performed cognitive tasks and hemodynamic signals detected by a DOT system. Our initial observation showed activation of oxy-hemoglobin concentration in BA 10, which is consistent with some results seen by positron emission tomography (PET) and functional magnetic resonance imaging (fMRI). Our study demonstrates the possibility of combining DOT with Stroop test to quantitatively investigate cognitive functions of the human brain at the prefrontal cortex.

Deep-tissue temperature mapping by multi-illumination photoacoustic tomography aided by a diffusion optical model: a numerical study

Science.gov (United States)

Zhou, Yuan; Tang, Eric; Luo, Jianwen; Yao, Junjie

2018-01-01

Temperature mapping during thermotherapy can help precisely control the heating process, both temporally and spatially, to efficiently kill the tumor cells and prevent the healthy tissues from heating damage. Photoacoustic tomography (PAT) has been used for noninvasive temperature mapping with high sensitivity, based on the linear correlation between the tissue's Grüneisen parameter and temperature. However, limited by the tissue's unknown optical properties and thus the optical fluence at depths beyond the optical diffusion limit, the reported PAT thermometry usually takes a ratiometric measurement at different temperatures and thus cannot provide absolute measurements. Moreover, ratiometric measurement over time at different temperatures has to assume that the tissue's optical properties do not change with temperatures, which is usually not valid due to the temperature-induced hemodynamic changes. We propose an optical-diffusion-model-enhanced PAT temperature mapping that can obtain the absolute temperature distribution in deep tissue, without the need of multiple measurements at different temperatures. Based on the initial acoustic pressure reconstructed from multi-illumination photoacoustic signals, both the local optical fluence and the optical parameters including absorption and scattering coefficients are first estimated by the optical-diffusion model, then the temperature distribution is obtained from the reconstructed Grüneisen parameters. We have developed a mathematic model for the multi-illumination PAT of absolute temperatures, and our two-dimensional numerical simulations have shown the feasibility of this new method. The proposed absolute temperature mapping method may set the technical foundation for better temperature control in deep tissue in thermotherapy.

Patch-based anisotropic diffusion scheme for fluorescence diffuse optical tomography--part 2: image reconstruction.

Science.gov (United States)

Correia, Teresa; Koch, Maximilian; Ale, Angelique; Ntziachristos, Vasilis; Arridge, Simon

2016-02-21

Fluorescence diffuse optical tomography (fDOT) provides 3D images of fluorescence distributions in biological tissue, which represent molecular and cellular processes. The image reconstruction problem is highly ill-posed and requires regularisation techniques to stabilise and find meaningful solutions. Quadratic regularisation tends to either oversmooth or generate very noisy reconstructions, depending on the regularisation strength. Edge preserving methods, such as anisotropic diffusion regularisation (AD), can preserve important features in the fluorescence image and smooth out noise. However, AD has limited ability to distinguish an edge from noise. We propose a patch-based anisotropic diffusion regularisation (PAD), where regularisation strength is determined by a weighted average according to the similarity between patches around voxels within a search window, instead of a simple local neighbourhood strategy. However, this method has higher computational complexity and, hence, we wavelet compress the patches (PAD-WT) to speed it up, while simultaneously taking advantage of the denoising properties of wavelet thresholding. Furthermore, structural information can be incorporated into the image reconstruction with PAD-WT to improve image quality and resolution. In this case, the weights used to average voxels in the image are calculated using the structural image, instead of the fluorescence image. The regularisation strength depends on both structural and fluorescence images, which guarantees that the method can preserve fluorescence information even when it is not structurally visible in the anatomical images. In part 1, we tested the method using a denoising problem. Here, we use simulated and in vivo mouse fDOT data to assess the algorithm performance. Our results show that the proposed PAD-WT method provides high quality and noise free images, superior to those obtained using AD.

An efficient method for model refinement in diffuse optical tomography

Science.gov (United States)

Zirak, A. R.; Khademi, M.

2007-11-01

Diffuse optical tomography (DOT) is a non-linear, ill-posed, boundary value and optimization problem which necessitates regularization. Also, Bayesian methods are suitable owing to measurements data are sparse and correlated. In such problems which are solved with iterative methods, for stabilization and better convergence, the solution space must be small. These constraints subject to extensive and overdetermined system of equations which model retrieving criteria specially total least squares (TLS) must to refine model error. Using TLS is limited to linear systems which is not achievable when applying traditional Bayesian methods. This paper presents an efficient method for model refinement using regularized total least squares (RTLS) for treating on linearized DOT problem, having maximum a posteriori (MAP) estimator and Tikhonov regulator. This is done with combination Bayesian and regularization tools as preconditioner matrices, applying them to equations and then using RTLS to the resulting linear equations. The preconditioning matrixes are guided by patient specific information as well as a priori knowledge gained from the training set. Simulation results illustrate that proposed method improves the image reconstruction performance and localize the abnormally well.

Consistency of ocular coherence tomography fast macular thickness mapping in diabetic diffuse macular edema

International Nuclear Information System (INIS)

Saraiva, Fabio Petersen; Costa, Patricia Grativol; Inomata, Daniela Lumi; Melo, Carlos Sergio Nascimento; Helal Junior, John; Nakashima, Yoshitaka

2007-01-01

Objectives: To investigate optical coherence tomography consistency on foveal thickness, foveal volume, and macular volume measurements in patients with and without diffuse diabetic macular edema. Introduction: Optical coherence tomography represents an objective technique that provides cross-sectional tomographs of retinal structure in vivo. However, it is expected that poor fixation ability, as seen in diabetic macular edema, could alter its results. Several authors have discussed the reproducibility of optical coherence tomography, but only a few have addressed the topic with respect to diabetic maculopathy. Methods: The study recruited diabetic patients without clinically evident retinopathy (control group) and with diffuse macular edema (case group). Only one eye of each patient was evaluated. Five consecutive fast macular scans were taken using Ocular Coherence Tomography 3; the 6 mm macular map was chosen. The consistency in measurements of foveal thickness, foveal volume, and total macular volume for both groups was evaluated using the Pearson's coefficient of variation. The T-test for independent samples was used in order to compare measurements of both groups. Results: Each group consisted of 20 patients. All measurements had a coefficient of variation less than 10%. The most consistent parameter for both groups was the total macular volume. Discussion: Consistency in measurement is a mainstay of any test. A test is unreliable if its measurements can not be correctly repeated. We found a good index of consistency, even considering patients with an unstable gaze. Conclusions: Optical coherence tomography is a consistent method for diabetic subjects with diffuse macular edema. (author)

Consistency of ocular coherence tomography fast macular thickness mapping in diabetic diffuse macular edema

Energy Technology Data Exchange (ETDEWEB)

Saraiva, Fabio Petersen; Costa, Patricia Grativol; Inomata, Daniela Lumi; Melo, Carlos Sergio Nascimento; Helal Junior, John; Nakashima, Yoshitaka [Universidade de Sao Paulo (USP), SP (Brazil). Hospital das Clinicas. Dept. de Oftalmologia]. E-mail: fabiopetersen@yahoo.com.br

2007-07-01

Objectives: To investigate optical coherence tomography consistency on foveal thickness, foveal volume, and macular volume measurements in patients with and without diffuse diabetic macular edema. Introduction: Optical coherence tomography represents an objective technique that provides cross-sectional tomographs of retinal structure in vivo. However, it is expected that poor fixation ability, as seen in diabetic macular edema, could alter its results. Several authors have discussed the reproducibility of optical coherence tomography, but only a few have addressed the topic with respect to diabetic maculopathy. Methods: The study recruited diabetic patients without clinically evident retinopathy (control group) and with diffuse macular edema (case group). Only one eye of each patient was evaluated. Five consecutive fast macular scans were taken using Ocular Coherence Tomography 3; the 6 mm macular map was chosen. The consistency in measurements of foveal thickness, foveal volume, and total macular volume for both groups was evaluated using the Pearson's coefficient of variation. The T-test for independent samples was used in order to compare measurements of both groups. Results: Each group consisted of 20 patients. All measurements had a coefficient of variation less than 10%. The most consistent parameter for both groups was the total macular volume. Discussion: Consistency in measurement is a mainstay of any test. A test is unreliable if its measurements can not be correctly repeated. We found a good index of consistency, even considering patients with an unstable gaze. Conclusions: Optical coherence tomography is a consistent method for diabetic subjects with diffuse macular edema. (author)

Characterizing Intraorbital Optic Nerve Changes on Diffusion Tensor Imaging in Thyroid Eye Disease Before Dysthyroid Optic Neuropathy.

Science.gov (United States)

Lee, Hwa; Lee, Young Hen; Suh, Sang-Il; Jeong, Eun-Kee; Baek, Sehyun; Seo, Hyung Suk

The aim of this study was to determine whether the optic nerve is affected by thyroid eye disease (TED) before the development of dysthyroid optic neuropathy with diffusion-tensor imaging (DTI). Twenty TED patients and 20 controls were included. The mean, axial, and radial diffusivities and fractional anisotropy (FA) value were measured at the optic nerves in DTI. Extraocular muscle diameters were measured on computed tomography. The diffusivities and FA of the optic nerves were compared between TED and controls and between active and inactive stages of TED. The correlations between these DTI parameters and the clinical features were determined. The mean, axial, and radial diffusivities were lower in TED compared with the controls (P optic nerve before dysthyroid optic neuropathy in TED. The FA, in particular, reflected TED activity and severity.

Contrast improvement of continuous wave diffuse optical tomography reconstruction by hybrid approach using least square and genetic algorithm

Science.gov (United States)

Patra, Rusha; Dutta, Pranab K.

2015-07-01

Reconstruction of the absorption coefficient of tissue with good contrast is of key importance in functional diffuse optical imaging. A hybrid approach using model-based iterative image reconstruction and a genetic algorithm is proposed to enhance the contrast of the reconstructed image. The proposed method yields an observed contrast of 98.4%, mean square error of 0.638×10-3, and object centroid error of (0.001 to 0.22) mm. Experimental validation of the proposed method has also been provided with tissue-like phantoms which shows a significant improvement in image quality and thus establishes the potential of the method for functional diffuse optical tomography reconstruction with continuous wave setup. A case study of finger joint imaging is illustrated as well to show the prospect of the proposed method in clinical diagnosis. The method can also be applied to the concentration measurement of a region of interest in a turbid medium.

Multispectral and phase-contrast diffuse optical tomography of breast cancer during neoadjuvant chemotherapy: a case study

Science.gov (United States)

Liang, Xiaoping; Zhang, Qizhi; Staal, Stephen; Grobmyer, Stephen; Jiang, Huabei

2009-02-01

Multispectral and phase-contrast diffuse optical tomography are used to track treatment progress in a patient with locally advanced invasive carcinoma of the breast cancer during neoadjuvant chemotherapy. Two types of chemotherapy treatment including four cycles of Adriamycin/Cytoxin (AC cycles) and twelve cycles of Taxol/Herceptin (TH cycles) were applied to patient. A total of eight optical exams were performed before and within the chemotherapy. Images of tissue refractive index, and absorption and scattering coefficients, as well as oxy-hemoglobin and deoxy-hemoglobin concentrations along with scattering particle volume fraction and mean diameter of cellular components were all obtained. The tumor was identified through absorption and scattering images. Tumor shrinkage was observed during the course of chemotherapy from all the optical images. Our results show that oxy-hemoglobin, deoxy-hemoglobin and total hemoglobin in tumor decreased after chemotherapy compared to that of before chemotherapy. Significant changes in tumor refractive index along with tumor cellular morphology during the entire chemotherapy are also observed.

Toward real-time diffuse optical tomography: accelerating light propagation modeling employing parallel computing on GPU and CPU.

Science.gov (United States)

Doulgerakis, Matthaios; Eggebrecht, Adam; Wojtkiewicz, Stanislaw; Culver, Joseph; Dehghani, Hamid

2017-12-01

Parameter recovery in diffuse optical tomography is a computationally expensive algorithm, especially when used for large and complex volumes, as in the case of human brain functional imaging. The modeling of light propagation, also known as the forward problem, is the computational bottleneck of the recovery algorithm, whereby the lack of a real-time solution is impeding practical and clinical applications. The objective of this work is the acceleration of the forward model, within a diffusion approximation-based finite-element modeling framework, employing parallelization to expedite the calculation of light propagation in realistic adult head models. The proposed methodology is applicable for modeling both continuous wave and frequency-domain systems with the results demonstrating a 10-fold speed increase when GPU architectures are available, while maintaining high accuracy. It is shown that, for a very high-resolution finite-element model of the adult human head with ∼600,000 nodes, consisting of heterogeneous layers, light propagation can be calculated at ∼0.25  s/excitation source. (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

Heterodyne frequency-domain multispectral diffuse optical tomography of breast cancer in the parallel-plane transmission geometry

Energy Technology Data Exchange (ETDEWEB)

Ban, H. Y.; Kavuri, V. C., E-mail: venk@physics.upenn.edu; Cochran, J. M.; Pathak, S.; Chung, S. H.; Yodh, A. G. [Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States); Schweiger, M.; Arridge, S. R. [Department of Computer Science, University College London, London WC1E 7JE (United Kingdom); Xie, L. [Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States); Busch, D. R. [Division of Neurology, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania 19104 (United States); Katrašnik, J. [Faculty of Electrical Engineering, University of Ljubljana, Ljubljana 1000 (Slovenia); Lee, K. [Daegu Gyeongbuk Institute of Science and Technology, Daegu 711-813 (Korea, Republic of); Choe, R. [Department of Biomedical Engineering, University of Rochester, Rochester, New York 14642 (United States); Czerniecki, B. J. [Department of Surgery, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States)

2016-07-15

Purpose: The authors introduce a state-of-the-art all-optical clinical diffuse optical tomography (DOT) imaging instrument which collects spatially dense, multispectral, frequency-domain breast data in the parallel-plate geometry. Methods: The instrument utilizes a CCD-based heterodyne detection scheme that permits massively parallel detection of diffuse photon density wave amplitude and phase for a large number of source–detector pairs (10{sup 6}). The stand-alone clinical DOT instrument thus offers high spatial resolution with reduced crosstalk between absorption and scattering. Other novel features include a fringe profilometry system for breast boundary segmentation, real-time data normalization, and a patient bed design which permits both axial and sagittal breast measurements. Results: The authors validated the instrument using tissue simulating phantoms with two different chromophore-containing targets and one scattering target. The authors also demonstrated the instrument in a case study breast cancer patient; the reconstructed 3D image of endogenous chromophores and scattering gave tumor localization in agreement with MRI. Conclusions: Imaging with a novel parallel-plate DOT breast imager that employs highly parallel, high-resolution CCD detection in the frequency-domain was demonstrated.

3D optical tomography in the presence of void regions

Science.gov (United States)

Riley, J.; Dehghani, Hamid; Schweiger, Martin; Arridge, Simon R.; Ripoll, Jorge; Nieto-Vesperinas, Manuel

2000-12-01

We present an investigation of the effect of a 3D non-scattering gap region on image reconstruction in diffuse optical tomography. The void gap is modelled by the Radiosity-Diffusion method and the inverse problem is solved using the adjoint field method. The case of a sphere with concentric spherical gap is used as an example.

Multi-source quantitative photoacoustic tomography in a diffusive regime

International Nuclear Information System (INIS)

Bal, Guillaume; Ren, Kui

2011-01-01

Photoacoustic tomography (PAT) is a novel hybrid medical imaging technique that aims to combine the large contrast of optical coefficients with the high-resolution capabilities of ultrasound. We assume that the first step of PAT, namely the reconstruction of a map of absorbed radiation from ultrasound boundary measurement, has been done. We focus on quantitative photoacoustic tomography, which aims at quantitatively reconstructing the optical coefficients from knowledge of the absorbed radiation map. We present a non-iterative procedure to reconstruct such optical coefficients, namely the diffusion and absorption coefficients, and the Grüneisen coefficient when the propagation of radiation is modeled by a second-order elliptic equation. We show that PAT measurements allow us to uniquely reconstruct only two out of the above three coefficients, even when data are collected using an arbitrary number of radiation illuminations. We present uniqueness and stability results for the reconstructions of two such parameters and demonstrate the accuracy of the reconstruction algorithm with numerical reconstructions from two-dimensional synthetic data

Investigation of detection limits for diffuse optical tomography systems: II. Analysis of slab and cup geometry for breast imaging.

Science.gov (United States)

Ziegler, Ronny; Brendel, Bernhard; Rinneberg, Herbert; Nielsen, Tim

2009-01-21

Using a statistical (chi-square) test on simulated data and a realistic noise model derived from the system's hardware we study the performance of diffuse optical tomography systems for fluorescence imaging. We compare the predicted smallest size of detectable lesions at various positions in slab and cup geometry and model how detection sensitivity depends on breast compression and lesion fluorescence contrast. Our investigation shows that lesion detection is limited by relative noise in slab geometry and by absolute noise in cup geometry.

Optical biopsy of lymph node morphology using optical coherence tomography.

Science.gov (United States)

Luo, Wei; Nguyen, Freddy T; Zysk, Adam M; Ralston, Tyler S; Brockenbrough, John; Marks, Daniel L; Oldenburg, Amy L; Boppart, Stephen A

2005-10-01

Optical diagnostic imaging techniques are increasingly being used in the clinical environment, allowing for improved screening and diagnosis while minimizing the number of invasive procedures. Diffuse optical tomography, for example, is capable of whole-breast imaging and is being developed as an alternative to traditional X-ray mammography. While this may eventually be a very effective screening method, other optical techniques are better suited for imaging on the cellular and molecular scale. Optical Coherence Tomography (OCT), for instance, is capable of high-resolution cross-sectional imaging of tissue morphology. In a manner analogous to ultrasound imaging except using optics, pulses of near-infrared light are sent into the tissue while coherence-gated reflections are measured interferometrically to form a cross-sectional image of tissue. In this paper we apply OCT techniques for the high-resolution three-dimensional visualization of lymph node morphology. We present the first reported OCT images showing detailed morphological structure and corresponding histological features of lymph nodes from a carcinogen-induced rat mammary tumor model, as well as from a human lymph node containing late stage metastatic disease. The results illustrate the potential for OCT to visualize detailed lymph node structures on the scale of micrometastases and the potential for the detection of metastatic nodal disease intraoperatively.

Monitoring early tumor response to drug therapy with diffuse optical tomography

Science.gov (United States)

Flexman, Molly L.; Vlachos, Fotios; Kim, Hyun Keol; Sirsi, Shashank R.; Huang, Jianzhong; Hernandez, Sonia L.; Johung, Tessa B.; Gander, Jeffrey W.; Reichstein, Ari R.; Lampl, Brooke S.; Wang, Antai; Borden, Mark A.; Yamashiro, Darrell J.; Kandel, Jessica J.; Hielscher, Andreas H.

2012-01-01

Although anti-angiogenic agents have shown promise as cancer therapeutics, their efficacy varies between tumor types and individual patients. Providing patient-specific metrics through rapid noninvasive imaging can help tailor drug treatment by optimizing dosages, timing of drug cycles, and duration of therapy--thereby reducing toxicity and cost and improving patient outcome. Diffuse optical tomography (DOT) is a noninvasive three-dimensional imaging modality that has been shown to capture physiologic changes in tumors through visualization of oxygenated, deoxygenated, and total hemoglobin concentrations, using non-ionizing radiation with near-infrared light. We employed a small animal model to ascertain if tumor response to bevacizumab (BV), an anti-angiogenic agent that targets vascular endothelial growth factor (VEGF), could be detected at early time points using DOT. We detected a significant decrease in total hemoglobin levels as soon as one day after BV treatment in responder xenograft tumors (SK-NEP-1), but not in SK-NEP-1 control tumors or in non-responder control or BV-treated NGP tumors. These results are confirmed by magnetic resonance imaging T2 relaxometry and lectin perfusion studies. Noninvasive DOT imaging may allow for earlier and more effective control of anti-angiogenic therapy.

Morpho-functional evaluation of torpedo maculopathy with optical coherence tomography angiography and microperimetry

Directory of Open Access Journals (Sweden)

Gabriela Grimaldi

2018-06-01

Full Text Available Purpose: To report the case of a 13-year-old girl with torpedo maculopathy, evaluated with multimodal morpho-functional retinal imaging, including fundus photography, infra-red and blue fundus autofluorescence, swept-source optical coherence tomography (OCT, en face OCT, OCT angiography and microperimetry (MP. Observations: On fundus examination, a torpedo-like hypopigmented lesion was observed temporal to the fovea in the left eye. OCT showed disruption of outer retinal layers and the presence of a subretinal cleft. On OCTA, a diffuse attenuation of signal from choriocapillaris was observed along the lesion. Functional analysis with MP revealed a reduction of retinal sensitivity over the lesion. Conclusions: and importance: On OCTA, torpedo maculopathy is characterized by vascular alterations of the choriocapillaris along the lesion. Keywords: Optical coherence tomography angiography, Torpedo maculopathy, Microperimetry, Swept-source optical coherence tomography, En face optical coherence tomography

Dynamic light scattering optical coherence tomography.

Science.gov (United States)

Lee, Jonghwan; Wu, Weicheng; Jiang, James Y; Zhu, Bo; Boas, David A

2012-09-24

We introduce an integration of dynamic light scattering (DLS) and optical coherence tomography (OCT) for high-resolution 3D imaging of heterogeneous diffusion and flow. DLS analyzes fluctuations in light scattered by particles to measure diffusion or flow of the particles, and OCT uses coherence gating to collect light only scattered from a small volume for high-resolution structural imaging. Therefore, the integration of DLS and OCT enables high-resolution 3D imaging of diffusion and flow. We derived a theory under the assumption that static and moving particles are mixed within the OCT resolution volume and the moving particles can exhibit either diffusive or translational motion. Based on this theory, we developed a fitting algorithm to estimate dynamic parameters including the axial and transverse velocities and the diffusion coefficient. We validated DLS-OCT measurements of diffusion and flow through numerical simulations and phantom experiments. As an example application, we performed DLS-OCT imaging of the living animal brain, resulting in 3D maps of the absolute and axial velocities, the diffusion coefficient, and the coefficient of determination.

Fréchet derivative with respect to the shape of a strongly convex nonscattering region in optical tomography

Science.gov (United States)

Hyvönen, Nuutti

2007-10-01

The aim of optical tomography is to reconstruct the optical properties inside a physical body, e.g. a neonatal head, by illuminating it with near-infrared light and measuring the outward flux of photons on the object boundary. Because a brain consists of strongly scattering tissue with imbedded cavities filled by weakly scattering cerebrospinal fluid, propagation of near-infrared photons in the human head can be treated by combining the diffusion approximation of the radiative transfer equation with geometrical optics to obtain the radiosity-diffusion forward model of optical tomography. At the moment, a disadvantage with the radiosity-diffusion model is that the locations of the transparent cavities must be known in advance in order to be able to reconstruct the physiologically interesting quantities, i.e., the absorption and the scatter in the strongly scattering brain tissue. In this work we show that the boundary measurement map of optical tomography is Fréchet differentiable with respect to the shape of a strongly convex nonscattering region. Using this result, we introduce a numerical algorithm for approximating an unknown nonscattering cavity by a ball if the background diffuse optical properties of the object are known. The functionality of the method is demonstrated through two-dimensional numerical experiments.

Towards real-time diffuse optical tomography for imaging brain functions cooperated with Kalman estimator

Science.gov (United States)

Wang, Bingyuan; Zhang, Yao; Liu, Dongyuan; Ding, Xuemei; Dan, Mai; Pan, Tiantian; Wang, Yihan; Li, Jiao; Zhou, Zhongxing; Zhang, Limin; Zhao, Huijuan; Gao, Feng

2018-02-01

Functional near-infrared spectroscopy (fNIRS) is a non-invasive neuroimaging method to monitor the cerebral hemodynamic through the optical changes measured at the scalp surface. It has played a more and more important role in psychology and medical imaging communities. Real-time imaging of brain function using NIRS makes it possible to explore some sophisticated human brain functions unexplored before. Kalman estimator has been frequently used in combination with modified Beer-Lamber Law (MBLL) based optical topology (OT), for real-time brain function imaging. However, the spatial resolution of the OT is low, hampering the application of OT in exploring some complicated brain functions. In this paper, we develop a real-time imaging method combining diffuse optical tomography (DOT) and Kalman estimator, much improving the spatial resolution. Instead of only presenting one spatially distributed image indicating the changes of the absorption coefficients at each time point during the recording process, one real-time updated image using the Kalman estimator is provided. Its each voxel represents the amplitude of the hemodynamic response function (HRF) associated with this voxel. We evaluate this method using some simulation experiments, demonstrating that this method can obtain more reliable spatial resolution images. Furthermore, a statistical analysis is also conducted to help to decide whether a voxel in the field of view is activated or not.

Local inversions in ultrasound-modulated optical tomography

International Nuclear Information System (INIS)

Bal, Guillaume; Moskow, Shari

2014-01-01

Ultrasound-modulated optical tomography is a hybrid imaging modality that aims to combine the high contrast of optical waves with the high resolution of ultrasound. We follow the model of the influence of ultrasound modulation on the light intensity measurements developed in Bal and Schotland (2010 Phys. Rev. Lett. 104 043902). We present sufficient conditions ensuring that the absorption and diffusion coefficients modeling light propagation can locally be uniquely and stably reconstructed from the corresponding available information. We present an iterative procedure to solve such a problem based on the analysis of linear elliptic systems of redundant partial differential equations. (paper)

Quantitative assessment of diffuse optical tomography sensitivity to the cerebral cortex using a whole-head probe

International Nuclear Information System (INIS)

Perdue, Katherine L; Diamond, Solomon G; Fang Qianqian

2012-01-01

We quantify the variability in diffuse optical tomography (DOT) sensitivity over the cortical surface in eight young adult subjects. We use the 10/5 electroencephalography system as a basis for our whole-head optical high-density probe design. The contrast-to-noise ratio (CNR) is calculated along with the percentage of the cortex that is above a CNR = 0 dB threshold. We also quantify the effect of including vasculature on the forward model and list our assumptions that allow us to estimate light penetration depth in the head. We show that using the 10/5 system for the optical probe design allows for the measurement of 37% of the cortical surface on average, with a mean CNR in the visible region of 5.5 dB. Certain anatomical regions, such as the lateral occipital cortex, had a very high percentage above the CNR threshold, while other regions such as the cingulate cortex were not measurable. Vasculature blocked optical sensitivity over 1% of the cortex. Cortical coverage was positively correlated with intracranial volume and relative cerebrospinal fluid volume, and negatively correlated with relative scalp volume and skull volume. These contributions allow experimenters to understand how anatomical variation in a subject population may impact DOT or functional near-infrared spectroscopy measurements. (paper)

Dynamic studies of small animals with a four-color diffuse optical tomography imager

International Nuclear Information System (INIS)

Schmitz, Christoph H.; Graber, Harry L.; Pei Yaling; Farber, Mark; Stewart, Mark; Levina, Rita D.; Levin, Mikhail B.; Xu Yong; Barbour, Randall L.

2005-01-01

We present newly developed instrumentation for full-tomographic four-wavelength, continuous wave, diffuse optical tomography (DOT) imaging on small animals. A small-animal imaging stage was constructed, from materials compatible with in-magnet studies, which offers stereotaxic fixation of the animal and precise, stable probe positioning. Instrument performance, based on calibration and phantom studies, demonstrates excellent long-term signal stability. DOT measurements of the functional rat brain response to electric paw stimulation are presented, and these demonstrate high data quality and excellent sensitivity to hemodynamic changes. A general linear model analysis on individual trials is used to localize and quantify the occurrence of functional behavior associated with the different hemoglobin state responses. Statistical evaluation of outcomes of individual trials is employed to identify significant regional response variations for different stimulation sites. Image results reveal a diffuse cortical response and a strong reaction of the thalamus, both indicative of activation of pain pathways by the stimulation. In addition, a weaker lateralized functional component is observed in the brain response, suggesting presence of motor activation. An important outcome of the experiment is that it shows that reactions to individual provocations can be monitored, without having to resort to signal averaging. Thus the described technology may be useful for studies of long-term trends in hemodynamic response, as would occur, for example, in behavioral studies involving freely moving animals

Toward real-time diffuse optical tomography: accelerating light propagation modeling employing parallel computing on GPU and CPU

Science.gov (United States)

Doulgerakis, Matthaios; Eggebrecht, Adam; Wojtkiewicz, Stanislaw; Culver, Joseph; Dehghani, Hamid

2017-12-01

Parameter recovery in diffuse optical tomography is a computationally expensive algorithm, especially when used for large and complex volumes, as in the case of human brain functional imaging. The modeling of light propagation, also known as the forward problem, is the computational bottleneck of the recovery algorithm, whereby the lack of a real-time solution is impeding practical and clinical applications. The objective of this work is the acceleration of the forward model, within a diffusion approximation-based finite-element modeling framework, employing parallelization to expedite the calculation of light propagation in realistic adult head models. The proposed methodology is applicable for modeling both continuous wave and frequency-domain systems with the results demonstrating a 10-fold speed increase when GPU architectures are available, while maintaining high accuracy. It is shown that, for a very high-resolution finite-element model of the adult human head with ˜600,000 nodes, consisting of heterogeneous layers, light propagation can be calculated at ˜0.25 s/excitation source.

Diffuse optical tomography with structured-light patterns to quantify breast density

Science.gov (United States)

Kwong, Jessica; Nouizi, Farouk; Cho, Jaedu; Zheng, Jie; Li, Yifan; Chen, Jeon-hor; Su, Min-Ying; Gulsen, Gultekin

2016-02-01

Breast density is an independent risk factor for breast cancer, where women with denser breasts are more likely to develop cancer. By identifying women at higher risk, healthcare providers can suggest screening at a younger age to effectively diagnose and treat breast cancer in its earlier stages. Clinical risk assessment models currently do not incorporate breast density, despite its strong correlation with breast cancer. Current methods to measure breast density rely on mammography and MRI, both of which may be difficult to use as a routine risk assessment tool. We propose to use diffuse optical tomography with structured-light to measure the dense, fibroglandular (FGT) tissue volume, which has a different chromophore signature than the surrounding adipose tissue. To test the ability of this technique, we performed simulations by creating numerical breast phantoms from segmented breast MR images. We looked at two different cases, one with a centralized FGT distribution and one with a dispersed distribution. As expected, the water and lipid volumes segmented at half-maximum were overestimated for the dispersed case. However, it was noticed that the recovered water and lipid concentrations were lower and higher, respectively, than the centralized case. This information may provide insight into the morphological distribution of the FGT and can be a correction in estimating the breast density.

New imaging algorithm in diffusion tomography

Science.gov (United States)

Klibanov, Michael V.; Lucas, Thomas R.; Frank, Robert M.

1997-08-01

A novel imaging algorithm for diffusion/optical tomography is presented for the case of the time dependent diffusion equation. Numerical tests are conducted for ranges of parameters realistic for applications to an early breast cancer diagnosis using ultrafast laser pulses. This is a perturbation-like method which works for both homogeneous a heterogeneous background media. Its main innovation lies in a new approach for a novel linearized problem (LP). Such an LP is derived and reduced to a boundary value problem for a coupled system of elliptic partial differential equations. As is well known, the solution of such a system amounts to the factorization of well conditioned, sparse matrices with few non-zero entries clustered along the diagonal, which can be done very rapidly. Thus, the main advantages of this technique are that it is fast and accurate. The authors call this approach the elliptic systems method (ESM). The ESM can be extended for other data collection schemes.

Artifact reduction method in ultrasound-guided diffuse optical tomography using exogenous contrast agents

Science.gov (United States)

Ardeshirpour, Yasaman; Biswal, Nrusingh; Aguirre, Andres; Zhu, Quing

2011-04-01

In diffuse optical tomography (DOT), a typical perturbation approach requires two sets of measurements obtained at the lesion breast (lesion or target site) and a contra-lateral location of the normal breast (reference site) for image reconstruction. For patients who have a small amount of breast tissue, the chest-wall underneath the breast tissue at both sites affects the imaging results. In this group of patients, the perturbation, which is the difference between measurements obtained at the lesion and reference sites, may include the information of background mismatch which can generate artifacts or affect the reconstructed quantitative absorption coefficient of the lesion. Also, for patients who have a single breast due to prior surgery, the contra-lateral reference is not available. To improve the DOT performance or overcome its limitation, we introduced a new method based on an exogenous contrast agent and demonstrate its performance using animal models. Co-registered ultrasound was used to guide the lesion localization. The results have shown that artifacts caused by background mismatch can be reduced significantly by using this new method.

Two-step reconstruction method using global optimization and conjugate gradient for ultrasound-guided diffuse optical tomography.

Science.gov (United States)

Tavakoli, Behnoosh; Zhu, Quing

2013-01-01

Ultrasound-guided diffuse optical tomography (DOT) is a promising method for characterizing malignant and benign lesions in the female breast. We introduce a new two-step algorithm for DOT inversion in which the optical parameters are estimated with the global optimization method, genetic algorithm. The estimation result is applied as an initial guess to the conjugate gradient (CG) optimization method to obtain the absorption and scattering distributions simultaneously. Simulations and phantom experiments have shown that the maximum absorption and reduced scattering coefficients are reconstructed with less than 10% and 25% errors, respectively. This is in contrast with the CG method alone, which generates about 20% error for the absorption coefficient and does not accurately recover the scattering distribution. A new measure of scattering contrast has been introduced to characterize benign and malignant breast lesions. The results of 16 clinical cases reconstructed with the two-step method demonstrates that, on average, the absorption coefficient and scattering contrast of malignant lesions are about 1.8 and 3.32 times higher than the benign cases, respectively.

Optical computed tomography for imaging the breast: first look

Science.gov (United States)

Grable, Richard J.; Ponder, Steven L.; Gkanatsios, Nikolaos A.; Dieckmann, William; Olivier, Patrick F.; Wake, Robert H.; Zeng, Yueping

2000-07-01

The purpose of the study is to compare computed tomography optical imaging with traditional breast imaging techniques. Images produced by computed tomography laser mammography (CTLMTM) scanner are compared with images obtained from mammography, and in some cases ultrasound and/or magnetic resonance imaging (MRI). During the CTLM procedure, a near infrared laser irradiates the breast and an array of photodiodes detectors records light scattered through the breast tissue. The laser and detectors rotate synchronously around the breast to acquire a series of slice data along the coronal place. The procedure is performed without any breast compression or optical matching fluid. Cross-sectional slices of the breast are produced using a reconstruction algorithm. Reconstruction based on the diffusion theory is used to produce cross-sectional slices of the breast. Multiple slice images are combined to produce a three dimensional volumetric array of the imaged breast. This array is used to derive axial and sagittal images of the breast corresponding to cranio-caudal and medio-lateral images used in mammography. Over 200 women and 3 men have been scanned in clinical trials. The most obvious features seen in images produced by the optical tomography scanner are vascularization and significant lesions. Breast features caused by fibrocystic changes and cysts are less obvious. Breast density does not appear to be a significant factor in the quality of the image. We see correlation of the optical image structure with that seen with traditional breast imaging techniques. Further testing is being conducted to explore the sensitivity and specificity of optical tomography of the breast.

Speckle contrast diffuse correlation tomography of complex turbid medium flow

Energy Technology Data Exchange (ETDEWEB)

Huang, Chong; Irwin, Daniel; Lin, Yu; Shang, Yu; He, Lian; Kong, Weikai; Yu, Guoqiang [Department of Biomedical Engineering, University of Kentucky, Lexington, Kentucky 40506 (United States); Luo, Jia [Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, Kentucky 40506 (United States)

2015-07-15

Purpose: Developed herein is a three-dimensional (3D) flow contrast imaging system leveraging advancements in the extension of laser speckle contrast imaging theories to deep tissues along with our recently developed finite-element diffuse correlation tomography (DCT) reconstruction scheme. This technique, termed speckle contrast diffuse correlation tomography (scDCT), enables incorporation of complex optical property heterogeneities and sample boundaries. When combined with a reflectance-based design, this system facilitates a rapid segue into flow contrast imaging of larger, in vivo applications such as humans. Methods: A highly sensitive CCD camera was integrated into a reflectance-based optical system. Four long-coherence laser source positions were coupled to an optical switch for sequencing of tomographic data acquisition providing multiple projections through the sample. This system was investigated through incorporation of liquid and solid tissue-like phantoms exhibiting optical properties and flow characteristics typical of human tissues. Computer simulations were also performed for comparisons. A uniquely encountered smear correction algorithm was employed to correct point-source illumination contributions during image capture with the frame-transfer CCD and reflectance setup. Results: Measurements with scDCT on a homogeneous liquid phantom showed that speckle contrast-based deep flow indices were within 12% of those from standard DCT. Inclusion of a solid phantom submerged below the liquid phantom surface allowed for heterogeneity detection and validation. The heterogeneity was identified successfully by reconstructed 3D flow contrast tomography with scDCT. The heterogeneity center and dimensions and averaged relative flow (within 3%) and localization were in agreement with actuality and computer simulations, respectively. Conclusions: A custom cost-effective CCD-based reflectance 3D flow imaging system demonstrated rapid acquisition of dense boundary

Digital optical tomography system for dynamic breast imaging

Science.gov (United States)

Flexman, Molly L.; Khalil, Michael A.; Al Abdi, Rabah; Kim, Hyun K.; Fong, Christopher J.; Desperito, Elise; Hershman, Dawn L.; Barbour, Randall L.; Hielscher, Andreas H.

2011-07-01

Diffuse optical tomography has shown promising results as a tool for breast cancer screening and monitoring response to chemotherapy. Dynamic imaging of the transient response of the breast to an external stimulus, such as pressure or a respiratory maneuver, can provide additional information that can be used to detect tumors. We present a new digital continuous-wave optical tomography system designed to simultaneously image both breasts at fast frame rates and with a large number of sources and detectors. The system uses a master-slave digital signal processor-based detection architecture to achieve a dynamic range of 160 dB and a frame rate of 1.7 Hz with 32 sources, 64 detectors, and 4 wavelengths per breast. Included is a preliminary study of one healthy patient and two breast cancer patients showing the ability to identify an invasive carcinoma based on the hemodynamic response to a breath hold.

Fiber optic based optical tomography sensor for monitoring plasma uniformity

International Nuclear Information System (INIS)

Benck, Eric C.; Etemadi, Kasra

2001-01-01

A new type of fiber optic based optical tomography sensor has been developed for in situ monitoring of plasma uniformity. Optical tomography inverts optical emission measurements into the actual plasma distribution without assuming radial symmetry. The new sensor is designed to operate with only two small windows and acquire the necessary data in less than a second. Optical tomography is being tested on an ICP-GEC RF plasma source. Variations in plasma uniformity are measured as a function of different plasma conditions

Optical Coherence Tomography

DEFF Research Database (Denmark)

Mogensen, Mette; Themstrup, Lotte; Banzhaf, Christina

2014-01-01

Optical coherence tomography (OCT) has developed rapidly since its first realisation in medicine and is currently an emerging technology in the diagnosis of skin disease. OCT is an interferometric technique that detects reflected and backscattered light from tissue and is often described as the o......Optical coherence tomography (OCT) has developed rapidly since its first realisation in medicine and is currently an emerging technology in the diagnosis of skin disease. OCT is an interferometric technique that detects reflected and backscattered light from tissue and is often described...

Diffuse nesidioblastosis diagnosed on a Ga-68 DOTATATE positron emission tomography/computerized tomography

International Nuclear Information System (INIS)

Arun, Sasikumar; Mittal, Bhagwant Rai; Shukla, Jaya; Bhattacharya, Anish; Kumar, Praveen

2013-01-01

The authors describe a 50 days old pre-term infant with persistent hyperinsulinemic hypoglycemia of infancy in whom 68 Ga DOTATATE positron emission tomography/computerized tomography scan showed diffusely increased tracer uptake in the entire pancreas with no abnormal tracer uptake anywhere else in the body, suggestive of a diffuse variant of nesidioblastosis. (author)

A surgical navigation system for non-contact diffuse optical tomography and intraoperative cone-beam CT

Science.gov (United States)

Daly, Michael J.; Muhanna, Nidal; Chan, Harley; Wilson, Brian C.; Irish, Jonathan C.; Jaffray, David A.

2014-02-01

A freehand, non-contact diffuse optical tomography (DOT) system has been developed for multimodal imaging with intraoperative cone-beam CT (CBCT) during minimally-invasive cancer surgery. The DOT system is configured for near-infrared fluorescence imaging with indocyanine green (ICG) using a collimated 780 nm laser diode and a nearinfrared CCD camera (PCO Pixelfly USB). Depending on the intended surgical application, the camera is coupled to either a rigid 10 mm diameter endoscope (Karl Storz) or a 25 mm focal length lens (Edmund Optics). A prototype flatpanel CBCT C-Arm (Siemens Healthcare) acquires low-dose 3D images with sub-mm spatial resolution. A 3D mesh is extracted from CBCT for finite-element DOT implementation in NIRFAST (Dartmouth College), with the capability for soft/hard imaging priors (e.g., segmented lymph nodes). A stereoscopic optical camera (NDI Polaris) provides real-time 6D localization of reflective spheres mounted to the laser and camera. Camera calibration combined with tracking data is used to estimate intrinsic (focal length, principal point, non-linear distortion) and extrinsic (translation, rotation) lens parameters. Source/detector boundary data is computed from the tracked laser/camera positions using radiometry models. Target registration errors (TRE) between real and projected boundary points are ~1-2 mm for typical acquisition geometries. Pre-clinical studies using tissue phantoms are presented to characterize 3D imaging performance. This translational research system is under investigation for clinical applications in head-and-neck surgery including oral cavity tumour resection, lymph node mapping, and free-flap perforator assessment.

Diffuse fluorescence tomography of exo- and endogenously labeled tumors

Science.gov (United States)

Balalaeva, Irina V.; Turchin, Ilya V.; Orlova, Anna G.; Plekhanov, Vladimir I.; Shirmanova, Marina V.; Kleshnin, Michail S.; Fiks, Ilya I.; Zagainova, Elena V.; Kamensky, Vladislav A.

2007-06-01

Strong light scattering and absorption limit observation of the internal structure of biological tissue. Only special tools for turbid media imaging, such as optical diffuse tomography, enable noninvasive investigation of the internal biological tissues, including visualization and intravital monitoring of deep tumors. In this work the preliminary results of diffuse fluorescence tomography (DFT) of small animals are presented. Usage of exogenous fluorophores, targeted specifically at tumor cells, and fluorescent proteins expressed endogenously can significantly increase the contrast of obtained images. Fluorescent compounds of different nature, such as sulphonated aluminium phthalocyanine (Photosens), red fluorescing proteins and CdTe/CdSe-core/shell nanocrystals (quantum dots) were applied. We tested diffuse fluorescence tomography method at model media, in post mortem and in vivo experiments. The animal was scanned in transilluminative configuration by low-frequency modulated light (1 kHz) from Nd:YAG laser with second harmonic generation at wavelength of 532 nm or semiconductor laser at wavelength of 655 nm. Quantum dots or protein DsRed2 in glass capsules (inner diameter 2-3 mm) were placed post mortem inside the esophagus of 7-day-old hairless rats to simulate marked tumors. Photosens was injected intravenously to linear mice with metastazing Lewis lung carcinoma. The reconstruction algorithm, based on Algebraic Reconstruction Technique, was created and tested numerically in model experiments. High contrast images of tumor simulating capsules with DsRed2 concentrations about 10 -6 M and quantum dots about 5x10 -11 M have been obtained. Organ distribution of Photosens and its accumulation in tumors and surrounding tissues of animals has been examined. We have conducted the monitoring of tumors, exogenously labeled by photosensitizer. This work demonstrates potential capabilities of DFT method for intravital detection and monitoring of deep fluorescent

Co-registration of fluorescence diffuse optical tomography (fDOT) with positron emission tomography (PET) and development of multi-angle fDOT

International Nuclear Information System (INIS)

Tong, X.

2012-01-01

This thesis concerns the image processing of fluorescence diffuse optical tomography (fDOT), following two axes: fDOT image co-registration with PET (positron emission tomography) image and improvement of fDOT image reconstructions using mirrors to collect additional projections. It is presented in two parts:In the first part, an automatic method to co-register the fDOT images with PET images has been developed to correlate all the information from each modality. This co-registration method is based on automatic detection of fiducial markers (FM) present in both modalities. The particularity of this method is the use of optical surface image obtained in fDOT imaging system, which serves to identify the Z position of FM in optical images. We tested this method on a model of mice bearing tumor xenografts of MEN2A cancer cells that mimic a human medullary thyroid carcinoma, after a double injection of radiotracer [ 18 F] 2-fluoro-2-Deoxy-D-glucose (FDG) for PET imaging and optical fluorescent infrared tracer Sentidye. With the accuracy of our method, we can demonstrate that the signal of Sentidye is present both in the tumor and surrounding vessels.The fDOT reconstruction image quality is degraded along the Z axis due to a limited number of projections for reconstruction. In the second part, the work is oriented towards a new method of fDOT image reconstruction with a new multi-angle data acquisition system in placing two mirrors on each side of the animal. This work was conducted in collaboration with the CS Department of University College London (UCL), a partner of the European project FMT-XCT. TOAST software developed by this team was used as source code for the reconstruction algorithm, and was modified to adapt to the concerned problem. After several tests on the adjustment of program parameters, we applied this method on a phantom that simulating the biological tissue and on mice. The results showed an improvement in the reconstructed image of a semi

Space-Varying Iterative Restoration of Diffuse Optical Tomograms Reconstructed by the Photon Average Trajectories Method

Directory of Open Access Journals (Sweden)

Kravtsenyuk Olga V

2007-01-01

Full Text Available The possibility of improving the spatial resolution of diffuse optical tomograms reconstructed by the photon average trajectories (PAT method is substantiated. The PAT method recently presented by us is based on a concept of an average statistical trajectory for transfer of light energy, the photon average trajectory (PAT. The inverse problem of diffuse optical tomography is reduced to a solution of an integral equation with integration along a conditional PAT. As a result, the conventional algorithms of projection computed tomography can be used for fast reconstruction of diffuse optical images. The shortcoming of the PAT method is that it reconstructs the images blurred due to averaging over spatial distributions of photons which form the signal measured by the receiver. To improve the resolution, we apply a spatially variant blur model based on an interpolation of the spatially invariant point spread functions simulated for the different small subregions of the image domain. Two iterative algorithms for solving a system of linear algebraic equations, the conjugate gradient algorithm for least squares problem and the modified residual norm steepest descent algorithm, are used for deblurring. It is shown that a gain in spatial resolution can be obtained.

Space-Varying Iterative Restoration of Diffuse Optical Tomograms Reconstructed by the Photon Average Trajectories Method

Directory of Open Access Journals (Sweden)

Vladimir V. Lyubimov

2007-01-01

Full Text Available The possibility of improving the spatial resolution of diffuse optical tomograms reconstructed by the photon average trajectories (PAT method is substantiated. The PAT method recently presented by us is based on a concept of an average statistical trajectory for transfer of light energy, the photon average trajectory (PAT. The inverse problem of diffuse optical tomography is reduced to a solution of an integral equation with integration along a conditional PAT. As a result, the conventional algorithms of projection computed tomography can be used for fast reconstruction of diffuse optical images. The shortcoming of the PAT method is that it reconstructs the images blurred due to averaging over spatial distributions of photons which form the signal measured by the receiver. To improve the resolution, we apply a spatially variant blur model based on an interpolation of the spatially invariant point spread functions simulated for the different small subregions of the image domain. Two iterative algorithms for solving a system of linear algebraic equations, the conjugate gradient algorithm for least squares problem and the modified residual norm steepest descent algorithm, are used for deblurring. It is shown that a 27% gain in spatial resolution can be obtained.

Multimodal breast cancer imaging using coregistered dynamic diffuse optical tomography and digital breast tomosynthesis

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Zimmermann, Bernhard B.; Deng, Bin; Singh, Bhawana; Martino, Mark; Selb, Juliette; Fang, Qianqian; Sajjadi, Amir Y.; Cormier, Jayne; Moore, Richard H.; Kopans, Daniel B.; Boas, David A.; Saksena, Mansi A.; Carp, Stefan A.

2017-04-01

Diffuse optical tomography (DOT) is emerging as a noninvasive functional imaging method for breast cancer diagnosis and neoadjuvant chemotherapy monitoring. In particular, the multimodal approach of combining DOT with x-ray digital breast tomosynthesis (DBT) is especially synergistic as DBT prior information can be used to enhance the DOT reconstruction. DOT, in turn, provides a functional information overlay onto the mammographic images, increasing sensitivity and specificity to cancer pathology. We describe a dynamic DOT apparatus designed for tight integration with commercial DBT scanners and providing a fast (up to 1 Hz) image acquisition rate to enable tracking hemodynamic changes induced by the mammographic breast compression. The system integrates 96 continuous-wave and 24 frequency-domain source locations as well as 32 continuous wave and 20 frequency-domain detection locations into low-profile plastic plates that can easily mate to the DBT compression paddle and x-ray detector cover, respectively. We demonstrate system performance using static and dynamic tissue-like phantoms as well as in vivo images acquired from the pool of patients recalled for breast biopsies at the Massachusetts General Hospital Breast Imaging Division.

Ambulatory diffuse optical tomography and multimodality physiological monitoring system for muscle and exercise applications

Science.gov (United States)

Hu, Gang; Zhang, Quan; Ivkovic, Vladimir; Strangman, Gary E.

2016-09-01

Ambulatory diffuse optical tomography (aDOT) is based on near-infrared spectroscopy (NIRS) and enables three-dimensional imaging of regional hemodynamics and oxygen consumption during a person's normal activities. Although NIRS has been previously used for muscle assessment, it has been notably limited in terms of the number of channels measured, the extent to which subjects can be ambulatory, and/or the ability to simultaneously acquire synchronized auxiliary data such as electromyography (EMG) or electrocardiography (ECG). We describe the development of a prototype aDOT system, called NINscan-M, capable of ambulatory tomographic imaging as well as simultaneous auxiliary multimodal physiological monitoring. Powered by four AA size batteries and weighing 577 g, the NINscan-M prototype can synchronously record 64-channel NIRS imaging data, eight channels of EMG, ECG, or other analog signals, plus force, acceleration, rotation, and temperature for 24+ h at up to 250 Hz. We describe the system's design, characterization, and performance characteristics. We also describe examples of isometric, cycle ergometer, and free-running ambulatory exercise to demonstrate tomographic imaging at 25 Hz. NINscan-M represents a multiuse tool for muscle physiology studies as well as clinical muscle assessment.

Reduction of Poisson noise in measured time-resolved data for time-domain diffuse optical tomography.

Science.gov (United States)

Okawa, S; Endo, Y; Hoshi, Y; Yamada, Y

2012-01-01

A method to reduce noise for time-domain diffuse optical tomography (DOT) is proposed. Poisson noise which contaminates time-resolved photon counting data is reduced by use of maximum a posteriori estimation. The noise-free data are modeled as a Markov random process, and the measured time-resolved data are assumed as Poisson distributed random variables. The posterior probability of the occurrence of the noise-free data is formulated. By maximizing the probability, the noise-free data are estimated, and the Poisson noise is reduced as a result. The performances of the Poisson noise reduction are demonstrated in some experiments of the image reconstruction of time-domain DOT. In simulations, the proposed method reduces the relative error between the noise-free and noisy data to about one thirtieth, and the reconstructed DOT image was smoothed by the proposed noise reduction. The variance of the reconstructed absorption coefficients decreased by 22% in a phantom experiment. The quality of DOT, which can be applied to breast cancer screening etc., is improved by the proposed noise reduction.

Optical Coherence Tomography of the Aging Kidney.

Science.gov (United States)

Andrews, Peter M; Wang, Hsing-Wen; Guo, Hengchang; Anderson, Erik; Falola, Reuben; Chen, Yu

2016-12-01

The aging kidney exhibits a progressive decline in renal function with characteristic histopathologic changes and is a risk factor for renal transplant. However, the degree to which the kidney exhibits this decline depends on several factors that vary from one individual to the next. Optical coherence tomography is an evolving noninvasive imaging technology that has recently been used to evaluate acute tubular necrosis of living-human donor kidneys before their transplant. With the increasing use of kidneys from older individuals, it is important to determine whether optical coherence tomography also can distinguish the histopathology associated with aging. In this investigation, we used Munich-Wistar rats to evaluate the ability of optical coherence tomography to detect histopathologic changes associated with aging. Optical coherence tomography observations were correlated with renal function and conventional light microscopic evaluation of these same kidneys. With the onset of severe proteinuria at 10 to 12 months of age, optical coherence tomography revealed tubular necrosis/atrophy, interstitial fibrosis, tubular dilation, and glomerulosclerosis. With a further deterioration in kidney function at 16 to 18 months of age (as indicated by rising creatinine levels), optical coherence tomography revealed more extensive interstitial fibrosis and tubular atrophy, increased tubular dilation with cyst formation and more sclerotic glomeruli. The foregoing observations suggest that optical coherence tomography can be used to detect the histopathology of progressive nephropathy associated with aging.

Influence of excitation light rejection on forward model mismatch in optical tomography

International Nuclear Information System (INIS)

Hwang, K; Pan, T; Joshi, A; Rasmussen, J C; Bangerth, W; Sevick-Muraca, E M

2006-01-01

Fluorescence enhanced tomography for molecular imaging requires low background for detection and accurate image reconstruction. In this contribution, we show that excitation light leakage is responsible for elevated background and can be minimized with the use of gradient index (GRIN) lenses when using fibre optics to collect propagated fluorescence light from tissue or other biological media. We show that the model mismatch between frequency-domain photon migration (FDPM) measurements and the diffusion approximation prediction is decreased when GRIN lenses are placed prior to the interference filters to provide efficient excitation light rejection. Furthermore, model mismatch is correlated to the degree of excitation light leakage. This work demonstrates the importance of proper light filtering when designing fluorescence optical imaging and tomography

Optical coherence tomography for glucose monitoring in blood

Science.gov (United States)

Ullah, Hafeez; Hussain, Fayyaz; Ikram, Masroor

2015-08-01

In this review, we have discussed the potential application of the emerging imaging modality, i.e., optical coherence tomography (OCT) for glucose monitoring in biological tissues. OCT provides monitoring of glucose diffusion in different fibrous tissues like in sclera by determining the permeability rate with acceptable accuracy both in type 1 and in type 2 diabetes. The maximum precision of glucose measurement in Intralipid suspensions, for example, with the OCT technique yields the accuracy up to 4.4 mM for 10 % Intralipid and 2.2 mM for 3 % Intralipid.

Diffuse abnormalities of the trachea: computed tomography findings

International Nuclear Information System (INIS)

Marchiori, Edson; Araujo Neto, Cesar de

2008-01-01

The aim of this pictorial essay was to present the main computed tomography findings seen in diffuse diseases of the trachea. The diseases studied included amyloidosis, tracheobronchopathia osteochondroplastica, tracheobronchomegaly, laryngotracheobronchial papillomatosis, lymphoma, neurofibromatosis, relapsing polychondritis, Wegener's granulomatosis, tuberculosis, paracoccidioidomycosis, and tracheobronchomalacia. The most common computed tomography finding was thickening of the walls of the trachea, with or without nodules, parietal calcifications, or involvement of the posterior wall. Although computed tomography allows the detection and characterization of diseases of the central airways, and the correlation with clinical data reduces the diagnostic possibilities, bronchoscopy with biopsy remains the most useful procedure for the diagnosis of diffuse lesions of the trachea. (author)

Optical coherence tomography patterns as predictors of visual outcome in dengue-related maculopathy.

Science.gov (United States)

Teoh, Stephen C; Chee, Caroline K; Laude, Augustinus; Goh, Kong Y; Barkham, Timothy; Ang, Brenda S

2010-03-01

The purpose of this study was to characterize the presentations, long-term outcomes, and visual prognostic factors in dengue-related maculopathy of 41 patients with dengue fever and impaired vision from dengue-related maculopathy in a retrospective noninterventional and observational series. The medical records of patients with dengue-related maculopathy diagnosed over 18 months between July 2004 and December 2005 at The Eye Institute, Tan Tock Seng Hospital and Communicable Disease Center, Singapore, were reviewed and followed up for 24 months. Visual acuity and symptoms (presence of scotoma on automated visual fields and Amsler grid) were correlated with optical coherence tomography evaluation. Mean age was 28.7 years and there were more men (53.7%). The most common visual complaints were blurring of vision (51.2%) and central scotoma (34.1%). Most patients recovered best-corrected visual acuity >20/40. Optical coherence tomography showed 3 patterns of maculopathy: 1) diffuse retinal thickening; 2) cystoid macular edema; and 3) foveolitis. The visual outcome was independent of the extent of edema, but scotomata persisted longest in patients with foveolitis and shortest with those with diffuse retinal thickening. Dengue-associated ocular inflammation is an emerging ophthalmic condition and often involves the posterior segment. Prognosis is variable. Patients usually regain good vision but may retain persistent scotomata even at 2 years despite clinical resolution of the disease. Optical coherence tomography patterns in dengue maculopathy are useful for characterization, monitoring, and prognostication of the visual defect.

Frequency domain fluorescence diffuse tomography of small animals

Science.gov (United States)

Orlova, Anna G.; Turchin, Ilya V.; Kamensky, Vladislav A.; Plehanov, Vladimir I.; Balalaeva, Irina V.; Sergeeva, Ekaterina A.; Shirmanova, Marina V.; Kleshnin, Michail S.

2007-05-01

Fluorescent compounds for selective cancer cell marking are used for development of novel medical diagnostic methods, investigation of the influence of external factors on tumor growth, regress and metastasis. Only special tools for turbid media imaging, such as optical diffusion tomography permit noninvasive monitoring of fluorescent-labeled tumor alterations deep in animal tissue. In this work, the results of preliminary experiments utilizing frequency-domain fluorescent diffusion tomography (FD FDT) experimental setup in small animal are presented. Low-frequency modulated light (1 kHz) from Nd:YAG laser with second harmonic generation at the wavelength of 532 nm was used in the setup. The transilluminative planar configuration was used in the setup. A series of model experiments has been conducted and show good agreement between theoretical and experimental fluorescence intensity. Models of deep tumors were created by two methods: (1) glass capsules containing fluorophore solution were inserted into esophagus of small animals to simulate marked tumors; (2) a suspension of transfected HEΚ293-Turbo-RFP cells was subcutaneously injected to small animal. The conducted experiments have shown that FD FDT allows one to detect the presence of labeled tumor cells in small animals, to determine the volume of an experimental tumor, to perform 3D tumor reconstruction, as well as to conduct monitoring investigations. The obtained results demonstrate the potential capability of the FD FDT method for noninvasive whole-body imaging in cancer studies, diagnostics and therapy.

Mapping cortical haemodynamics during neonatal seizures using diffuse optical tomography: A case study

Directory of Open Access Journals (Sweden)

Harsimrat Singh

2014-01-01

Full Text Available Seizures in the newborn brain represent a major challenge to neonatal medicine. Neonatal seizures are poorly classified, under-diagnosed, difficult to treat and are associated with poor neurodevelopmental outcome. Video-EEG is the current gold-standard approach for seizure detection and monitoring. Interpreting neonatal EEG requires expertise and the impact of seizures on the developing brain remains poorly understood. In this case study we present the first ever images of the haemodynamic impact of seizures on the human infant brain, obtained using simultaneous diffuse optical tomography (DOT and video-EEG with whole-scalp coverage. Seven discrete periods of ictal electrographic activity were observed during a 60 minute recording of an infant with hypoxic–ischaemic encephalopathy. The resulting DOT images show a remarkably consistent, high-amplitude, biphasic pattern of changes in cortical blood volume and oxygenation in response to each electrographic event. While there is spatial variation across the cortex, the dominant haemodynamic response to seizure activity consists of an initial increase in cortical blood volume prior to a large and extended decrease typically lasting several minutes. This case study demonstrates the wealth of physiologically and clinically relevant information that DOT–EEG techniques can yield. The consistency and scale of the haemodynamic responses observed here also suggest that DOT–EEG has the potential to provide improved detection of neonatal seizures.

Impact of errors in experimental parameters on reconstructed breast images using diffuse optical tomography.

Science.gov (United States)

Deng, Bin; Lundqvist, Mats; Fang, Qianqian; Carp, Stefan A

2018-03-01

Near-infrared diffuse optical tomography (NIR-DOT) is an emerging technology that offers hemoglobin based, functional imaging tumor biomarkers for breast cancer management. The most promising clinical translation opportunities are in the differential diagnosis of malignant vs. benign lesions, and in early response assessment and guidance for neoadjuvant chemotherapy. Accurate quantification of the tissue oxy- and deoxy-hemoglobin concentration across the field of view, as well as repeatability during longitudinal imaging in the context of therapy guidance, are essential for the successful translation of NIR-DOT to clinical practice. The ill-posed and ill-condition nature of the DOT inverse problem makes this technique particularly susceptible to model errors that may occur, for example, when the experimental conditions do not fully match the assumptions built into the image reconstruction process. To evaluate the susceptibility of DOT images to experimental errors that might be encountered in practice for a parallel-plate NIR-DOT system, we simulated 7 different types of errors, each with a range of magnitudes. We generated simulated data by using digital breast phantoms derived from five actual mammograms of healthy female volunteers, to which we added a 1-cm tumor. After applying each of the experimental error types and magnitudes to the simulated measurements, we reconstructed optical images with and without structural prior guidance and assessed the overall error in the total hemoglobin concentrations (HbT) and in the HbT contrast between the lesion and surrounding area vs. the best-case scenarios. It is found that slight in-plane probe misalignment and plate rotation did not result in large quantification errors. However, any out-of-plane probe tilting could result in significant deterioration in lesion contrast. Among the error types investigated in this work, optical images were the least likely to be impacted by breast shape inaccuracies but suffered the

Comparisons of hybrid radiosity-diffusion model and diffusion equation for bioluminescence tomography in cavity cancer detection

Science.gov (United States)

Chen, Xueli; Yang, Defu; Qu, Xiaochao; Hu, Hao; Liang, Jimin; Gao, Xinbo; Tian, Jie

2012-06-01

Bioluminescence tomography (BLT) has been successfully applied to the detection and therapeutic evaluation of solid cancers. However, the existing BLT reconstruction algorithms are not accurate enough for cavity cancer detection because of neglecting the void problem. Motivated by the ability of the hybrid radiosity-diffusion model (HRDM) in describing the light propagation in cavity organs, an HRDM-based BLT reconstruction algorithm was provided for the specific problem of cavity cancer detection. HRDM has been applied to optical tomography but is limited to simple and regular geometries because of the complexity in coupling the boundary between the scattering and void region. In the provided algorithm, HRDM was first applied to three-dimensional complicated and irregular geometries and then employed as the forward light transport model to describe the bioluminescent light propagation in tissues. Combining HRDM with the sparse reconstruction strategy, the cavity cancer cells labeled with bioluminescent probes can be more accurately reconstructed. Compared with the diffusion equation based reconstruction algorithm, the essentiality and superiority of the HRDM-based algorithm were demonstrated with simulation, phantom and animal studies. An in vivo gastric cancer-bearing nude mouse experiment was conducted, whose results revealed the ability and feasibility of the HRDM-based algorithm in the biomedical application of gastric cancer detection.

Derivation of a Monte Carlo method for modeling heterodyne detection in optical coherence tomography systems

DEFF Research Database (Denmark)

Tycho, Andreas; Jørgensen, Thomas Martini; Andersen, Peter E.

2002-01-01

A Monte Carlo (MC) method for modeling optical coherence tomography (OCT) measurements of a diffusely reflecting discontinuity emb edded in a scattering medium is presented. For the first time to the authors' knowledge it is shown analytically that the applicability of an MC approach to this opti...

Diffusion tensor imaging of the optic tracts in multiple sclerosis: association with retinal thinning and visual disability.

Science.gov (United States)

Dasenbrock, Hormuzdiyar H; Smith, Seth A; Ozturk, Arzu; Farrell, Sheena K; Calabresi, Peter A; Reich, Daniel S

2011-04-01

Visual disability is common in multiple sclerosis, but its relationship to abnormalities of the optic tracts remains unknown. Because they are only rarely affected by lesions, the optic tracts may represent a good model for assessing the imaging properties of normal-appearing white matter in multiple sclerosis. Whole-brain diffusion tensor imaging was performed on 34 individuals with multiple sclerosis and 26 healthy volunteers. The optic tracts were reconstructed by tractography, and tract-specific diffusion indices were quantified. In the multiple-sclerosis group, peripapillary retinal nerve-fiber-layer thickness and total macular volume were measured by optical coherence tomography, and visual acuity at 100%, 2.5%, and 1.25% contrast was examined. After adjusting for age and sex, optic-tract mean and perpendicular diffusivity were higher (P=.002) in multiple sclerosis. Lower optic-tract fractional anisotropy was correlated with retinal nerve-fiber-layer thinning (r=.51, P=.003) and total-macular-volume reduction (r=.59, P=.002). However, optic-tract diffusion indices were not specifically correlated with visual acuity or with their counterparts in the optic radiation. Optic-tract diffusion abnormalities are associated with retinal damage, suggesting that both may be related to optic-nerve injury, but do not appear to contribute strongly to visual disability in multiple sclerosis. Copyright © 2010 by the American Society of Neuroimaging.

Fluorescence diffuse tomography for tumor detection and monitoring

Science.gov (United States)

Balalaeva, Irina V.; Orlova, Anna G.; Shirmanova, Marina V.; Kibraeva, Elena A.; Zagainova, Elena V.; Turchin, Ilya V.

2007-05-01

Strong light scattering and absorption limit visualization of the internal structure of biological tissue. Only special tools for turbid media imaging, such as optical diffuse tomography, enable noninvasive investigation of the internal biological tissues, including visualization and intravital monitoring of deep tumors. In this work the preliminary results of fluorescence diffuse tomography (FDT) of small animals are presented. Using of exogenous fluorophores, targeted specifically at tumor cells, and fluorescent proteins expressed endogenously can significantly increase the contrast of obtained images. Fluorescent compounds of different nature, such as sulphonated aluminium phthalocyanine (Photosens), red fluorescing proteins and CdTe/CdSe-core/shell nanocrystals (quantum dots) were applied. The animal was scanned in the transilluminative configuration by low-frequency modulated light (1 kHz) from Nd:YAG laser with second harmonic generation at the wavelength of 532 nm or semiconductor laser at the wavelength of 655 nm. Photosens was injected intravenously into linear mice with metastazing Lewis lung carcinoma in dose 4 mg/kg. Quantum dots (5x10 -11 M) or protein DsRed2 (1-5x10 -6 M) in glass capsules (inner diameter 2-3 mm) were placed inside the esophagus of 7-day-old hairless rats (18-20 g) to simulate marked tumors. Cells of HEK-293 Phoenix line, transitory transfected with Turbo-RFP protein gene, were injected hypodermically to immunodeficient mice. This work demonstrates potential capabilities of FDT method for detection and monitoring of deep fluorescent-labeled tumors in animal models. Strong advantages of fluorescent proteins and quantum dots over the traditional photosensitizer for FDT imaging are shown.

Optical Tomography in Combustion

DEFF Research Database (Denmark)

Evseev, Vadim

spectral measurements at several line-of-sights with a view to applications for tomographic measurements on full-scale industrial combustion systems. The system was successfully applied on industrial scale for simultaneous fast exhaust gas temperature measurements in the three optical ports of the exhaust......D project, it was also important to investigate the spectral properties of major combustion species such as carbon dioxide and carbon monoxide in the infrared range at high temperatures to provide the theoretical background for the development of the optical tomography methods. The new software....... JQSRT 113 (2012) 2222, 10.1016/j.jqsrt.2012.07.015] included in the PhD thesis as an attachment. The knowledge and experience gained in the PhD project is the first important step towards introducing the advanced optical tomography methods of combustion diagnostics developed in the project to future...

Optical coherent tomography measurements of the diffusion rate of water and drugs in an isolated and whole cornea

International Nuclear Information System (INIS)

Larin, Kirill V; Ghosn, M G

2006-01-01

The passive diffusion of drugs through the epithelial surfaces of an eye (the most widespread method for medical treatment of various diseases) is considered. The permeability of water and drugs through rabbit cornea was measured in the isolated cornea (separate from an eye) and in the whole cornea. The permeability coefficients of water and dexamethasone were estimated by the method of optical coherence tomography (OCT). Because multiple photon scattering introduces noise and distortions to the OCT signal, measurements were performed at depths up to 500 μm where most likely single scattering of light occurs in cornea. It is shown that the permeability coefficients in the isolated and whole cornea strongly differ from each other. For example, the water permeability in the isolated and whole cornea is (7.09±0.12)x10 -5 and (1.71±0.51)x10 -5 cm s -1 , respectively. (special issue devoted to multiple radiation scattering in random media)

A study of MRI-guided diffuse fluorescence molecular tomography for monitoring PDT effects in pancreas cancer

Science.gov (United States)

Samkoe, Kimberley S.; Davis, Scott C.; Srinivasan, Subhadra; O'Hara, Julia A.; Hasan, Tayyaba; Pogue, Brian W.

2009-06-01

Over the last several decades little progress has been made in the therapy and treatment monitoring of pancreas adenocarcinoma, a devastating and aggressive form of cancer that has a 5-year patient survival rate of 3%. Currently, investigations for the use of interstitial Verteporfin photodynamic therapy (PDT) are being undertaken in both orthotopic xenograft mouse models and in human clinical trials. In the mouse models, magnetic resonance (MR) imaging has been used as a measure of surrogate response to Verteporfin PDT; however, MR imaging alone lacks the molecular information required to assess the metabolic function and growth rates of the tumor immediately after treatment. We propose the implementation of MR-guided fluorescence tomography in conjunction with a fluorescently labeled (IR-Dye 800 CW, LI-COR) epidermal growth factor (EGF) as a molecular measure of surrogate response. To demonstrate the effectiveness of MR-guided diffuse fluorescence tomography for molecular imaging, we have used the AsPC-1 (+EGFR) human pancreatic adenocarcinoma in an orthotopic mouse model. EGF IRDye 800CW was injected 48 hours prior to imaging. MR image sequences were collected simultaneously with the fluorescence data using a MR-coupled diffuse optical tomography system. Image reconstruction was performed multiple times with varying abdominal organ segmentation in order to obtain a optimal tomographic image. It is shown that diffuse fluorescence tomography of the orthotopic pancreas model is feasible, with consideration of confounding fluorescence signals from the multiple organs and tissues surrounding the pancreas. MR-guided diffuse fluorescence tomography will be used to monitor EGF response after photodynamic therapy. Additionally, it provide the opportunity to individualize subsequent therapies based on response to PDT as well as to evaluate the success of combination therapies, such as PDT with chemotherapy, antibody therapy or even radiation.

Conical wavefronts in optics and tomography

International Nuclear Information System (INIS)

Soroko, L.M.

1990-01-01

A wide range of techniques in which the information is transferred by conical (nonspherical and nonplanar) wave fronts is considered. This is the first summary of papers published in the field of mesooptics and optical tomography. After the introduction into the new branch of modern optics - mesooptics -the properties of conical wavefronts are treated in detail. Some possible applications of mesooptics in science and technology are considered. The long history of mesooptics treated in the last chapter of this review lecture goes from the early stage of our Universe, gravitational lens, first publications in the last century and up-to-date innovations in optics, mesooptics and optical tomography. 3 refs

Implementation of a computationally efficient least-squares algorithm for highly under-determined three-dimensional diffuse optical tomography problems.

Science.gov (United States)

Yalavarthy, Phaneendra K; Lynch, Daniel R; Pogue, Brian W; Dehghani, Hamid; Paulsen, Keith D

2008-05-01

Three-dimensional (3D) diffuse optical tomography is known to be a nonlinear, ill-posed and sometimes under-determined problem, where regularization is added to the minimization to allow convergence to a unique solution. In this work, a generalized least-squares (GLS) minimization method was implemented, which employs weight matrices for both data-model misfit and optical properties to include their variances and covariances, using a computationally efficient scheme. This allows inversion of a matrix that is of a dimension dictated by the number of measurements, instead of by the number of imaging parameters. This increases the computation speed up to four times per iteration in most of the under-determined 3D imaging problems. An analytic derivation, using the Sherman-Morrison-Woodbury identity, is shown for this efficient alternative form and it is proven to be equivalent, not only analytically, but also numerically. Equivalent alternative forms for other minimization methods, like Levenberg-Marquardt (LM) and Tikhonov, are also derived. Three-dimensional reconstruction results indicate that the poor recovery of quantitatively accurate values in 3D optical images can also be a characteristic of the reconstruction algorithm, along with the target size. Interestingly, usage of GLS reconstruction methods reduces error in the periphery of the image, as expected, and improves by 20% the ability to quantify local interior regions in terms of the recovered optical contrast, as compared to LM methods. Characterization of detector photo-multiplier tubes noise has enabled the use of the GLS method for reconstructing experimental data and showed a promise for better quantification of target in 3D optical imaging. Use of these new alternative forms becomes effective when the ratio of the number of imaging property parameters exceeds the number of measurements by a factor greater than 2.

Extracting subsurface fingerprints using optical coherence tomography

CSIR Research Space (South Africa)

Akhoury, SS

2015-02-01

Full Text Available Subsurface Fingerprints using Optical Coherence Tomography Sharat Saurabh Akhoury, Luke Nicholas Darlow Modelling and Digital Science, Council for Scientific and Industrial Research, Pretoria, South Africa Abstract Physiologists have found... approach to extract the subsurface fingerprint representation using a high-resolution imaging technology known as Optical Coherence Tomography (OCT). ...

Imaging granulomatous lesions with optical coherence tomography

DEFF Research Database (Denmark)

Banzhaf, Christina; Jemec, Gregor B E

2012-01-01

To investigate and compare the presentation of granulomatous lesions in optical coherence tomography (OCT) images and compare this to previous studies of nonmelanoma skin tumors.......To investigate and compare the presentation of granulomatous lesions in optical coherence tomography (OCT) images and compare this to previous studies of nonmelanoma skin tumors....

Autofluorescence and spectral-domain optical coherence tomography of optic disk melanocytoma.

Science.gov (United States)

Guerra, Ricardo Luz Leitão; Marback, Eduardo Ferrari; Silva, Igor Sandes Pessoa da; Maia Junior, Otacílio de Oliveira; Marback, Roberto Lorens

2014-01-01

The authors report fundus autofluorescence (FAF) and spectral-domain optical coherence tomography (OCT) findings of two consecutive patients who presented with optic disk melanocytoma (ODM). A retrospective study was performed by reviewing medical records and ophthalmic imaging examinations. Optical coherence tomography findings were sloped and brightly reflective anterior tumor surface, adjacent retinal desorganization and abrupt posterior optical shadowing. Vitreous seeds were found in one patient. Fundus autofluorescence revealed outstanding hypoautofluorescence at the tumor area and isoautofluorescence at the remaining retina. Optical coherence tomography findings of the reported cases are consistent with those reported in the reviewed literature. Fundus autofluorescence has been used in the assessment of choroidal melanocytic tumors, but not yet in melanocytomas. We assume that this is the first report of these findings and believe that when its pattern has become clearly defined, fundus autofluorescence will be a useful tool to avoid misdiagnosis in suspicious cases and for follow-up.

Autofluorescence and spectral-domain optical coherence tomography of optic disk melanocytoma

Directory of Open Access Journals (Sweden)

Ricardo Luz Leitão Guerra

2014-12-01

Full Text Available The authors report fundus autofluorescence (FAF and spectral-domain optical coherence tomography (OCT findings of two consecutive patients who presented with optic disk melanocytoma (ODM. A retrospective study was performed by reviewing medical records and ophthalmic imaging examinations. Optical coherence tomography findings were sloped and brightly reflective anterior tumor surface, adjacent retinal desorganization and abrupt posterior optical shadowing. Vitreous seeds were found in one patient. Fundus autofluorescence revealed outstanding hypoautofluorescence at the tumor area and isoautofluorescence at the remaining retina. Optical coherence tomography findings of the reported cases are consistent with those reported in the reviewed literature. Fundus autofluorescence has been used in the assessment of choroidal melanocytic tumors, but not yet in melanocytomas. We assume that this is the first report of these findings and believe that when its pattern has become clearly defined, fundus autofluorescence will be a useful tool to avoid misdiagnosis in suspicious cases and for follow-up.

In-vivo dynamic characterization of microneedle skin penetration using optical coherence tomography

Science.gov (United States)

Enfield, Joey; O'Connell, Marie-Louise; Lawlor, Kate; Jonathan, Enock; O'Mahony, Conor; Leahy, Martin

2010-07-01

The use of microneedles as a method of circumventing the barrier properties of the stratum corneum is receiving much attention. Although skin disruption technologies and subsequent transdermal diffusion rates are being extensively studied, no accurate data on depth and closure kinetics of microneedle-induced skin pores are available, primarily due to the cumbersome techniques currently required for skin analysis. We report on the first use of optical coherence tomography technology to image microneedle penetration in real time and in vivo. We show that optical coherence tomography (OCT) can be used to painlessly measure stratum corneum and epidermis thickness, as well as microneedle penetration depth after microneedle insertion. Since OCT is a real-time, in-vivo, nondestructive technique, we also analyze skin healing characteristics and present quantitative data on micropore closure rate. Two locations (the volar forearm and dorsal aspect of the fingertip) have been assessed as suitable candidates for microneedle administration. The results illustrate the applicability of OCT analysis as a tool for microneedle-related skin characterization.

Whole-head functional brain imaging of neonates at cot-side using time-resolved diffuse optical tomography

Science.gov (United States)

Dempsey, Laura A.; Cooper, Robert J.; Powell, Samuel; Edwards, Andrea; Lee, Chuen-Wai; Brigadoi, Sabrina; Everdell, Nick; Arridge, Simon; Gibson, Adam P.; Austin, Topun; Hebden, Jeremy C.

2015-07-01

We present a method for acquiring whole-head images of changes in blood volume and oxygenation from the infant brain at cot-side using time-resolved diffuse optical tomography (TR-DOT). At UCL, we have built a portable TR-DOT device, known as MONSTIR II, which is capable of obtaining a whole-head (1024 channels) image sequence in 75 seconds. Datatypes extracted from the temporal point spread functions acquired by the system allow us to determine changes in absorption and reduced scattering coefficients within the interrogated tissue. This information can then be used to define clinically relevant measures, such as oxygen saturation, as well as to reconstruct images of relative changes in tissue chromophore concentration, notably those of oxy- and deoxyhaemoglobin. Additionally, the effective temporal resolution of our system is improved with spatio-temporal regularisation implemented through a Kalman filtering approach, allowing us to image transient haemodynamic changes. By using this filtering technique with intensity and mean time-of-flight datatypes, we have reconstructed images of changes in absorption and reduced scattering coefficients in a dynamic 2D phantom. These results demonstrate that MONSTIR II is capable of resolving slow changes in tissue optical properties within volumes that are comparable to the preterm head. Following this verification study, we are progressing to imaging a 3D dynamic phantom as well as the neonatal brain at cot-side. Our current study involves scanning healthy babies to demonstrate the quality of recordings we are able to achieve in this challenging patient population, with the eventual goal of imaging functional activation and seizures.

Multi-spectral and fluorescence diffuse optical tomography of breast cancer

Science.gov (United States)

Corlu, Alper

Multi-spectral and fluorescence diffuse optical tomography (DOT) techniques are explored and applied to image human breast cancer in vivo. Image reconstruction algorithms that utilize first and second order gradient information are described in detail. Breast DOT requires large computational memory and long run times. To this end, parallel computation techniques were developed appropriate to each reconstruction algorithm. A parallel plate DOT instrument developed for breast cancer imaging is described. The system relies heavily on continuous-wave (CW) transmission measurements and utilizes frequency domain (FD) measurements on the reemission side. However, traditional DOT image reconstruction methods based on CW measurements fail to separate tissue absorption and scattering uniquely. In this manuscript, multi-spectral DOT is shown to be capable of minimizing cross-talk and retrieving spectral parameters almost uniquely when the measurement wavelengths are optimized. A theoretical framework to select optimum wavelengths is provided, and tested with computer simulations. Results from phantom spectroscopy experiments and in vivo patient measurements support the notion that multi-spectral methods are superior to traditional DOT image reconstruction schemes. The same breast DOT instrument is improved and utilized to obtain the first in vivo images of human breast cancer based on fluorescence DOT (FDOT). To this end the fluorophore Indocyanine Green (ICG) is injected intravenously and fluorescence excitation and detection are accomplished in the soft-compression, parallel-plane, transmission geometry using laser sources at 786 nm and spectrally filtered CCD detection. Careful phantom and in vivo measurements are carried on to assure that the signals are due to ICG fluorescence, rather than tissue autofluorescence and excitation light leakage. An in vivo measurement protocol is designed to maximize the ICG contrast by acquiring full fluorescence tomographic scan during

Intra-operative application of optical coherence tomography with an operating microscope.

Science.gov (United States)

Just, T; Lankenau, E; Hüttmann, G; Pau, H W

2009-09-01

To introduce the use of optical coherence tomography with an operating microscope for intra-operative evaluation of the human larynx. A specially equipped operating microscope with integrated spectral domain optical coherence tomography apparatus was used during microlaryngoscopy. Technical improvements in optical coherence tomography equipment (e.g. pilot beam, variable focal distance, improved image quality and integration into an operating microscope) have enabled greater sensitivity and imaging speed and a non-contact approach. Spectral domain optical coherence tomography now enables a better correlation between optical coherence tomography images and histological findings. With this new technology, the precision of biopsy can be improved during microlaryngoscopy. Use of this new optical coherence tomography technology, integrated into an operating microscope, enables the surgeon to define the biopsy site location and resection plane precisely, while the optical zoom of the operating microscope can be used over the complete range.

Intracoronary optical coherence tomography

DEFF Research Database (Denmark)

Tenekecioglu, Erhan; Albuquerque, Felipe N; Sotomi, Yohei

2017-01-01

By providing valuable information about the coronary artery wall and lumen, intravascular imaging may aid in optimizing interventional procedure results and thereby could improve clinical outcomes following percutaneous coronary intervention (PCI). Intravascular optical coherence tomography (OCT...

Systematic calibration of an integrated x-ray and optical tomography system for preclinical radiation research

Energy Technology Data Exchange (ETDEWEB)

Yang, Yidong, E-mail: yidongyang@med.miami.edu [Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland 21231 and Department of Radiation Oncology, University of Miami School of Medicine, Miami, Florida 33136 (United States); Wang, Ken Kang-Hsin; Wong, John W. [Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland 21231 (United States); Eslami, Sohrab; Iordachita, Iulian I. [Laboratory for Computational Sensing and Robotics, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Patterson, Michael S. [Juravinski Cancer Centre and Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, Ontario L8S4K1 (Canada)

2015-04-15

Purpose: The cone beam computed tomography (CBCT) guided small animal radiation research platform (SARRP) has been developed for focal tumor irradiation, allowing laboratory researchers to test basic biological hypotheses that can modify radiotherapy outcomes in ways that were not feasible previously. CBCT provides excellent bone to soft tissue contrast, but is incapable of differentiating tumors from surrounding soft tissue. Bioluminescence tomography (BLT), in contrast, allows direct visualization of even subpalpable tumors and quantitative evaluation of tumor response. Integration of BLT with CBCT offers complementary image information, with CBCT delineating anatomic structures and BLT differentiating luminescent tumors. This study is to develop a systematic method to calibrate an integrated CBCT and BLT imaging system which can be adopted onboard the SARRP to guide focal tumor irradiation. Methods: The integrated imaging system consists of CBCT, diffuse optical tomography (DOT), and BLT. The anatomy acquired from CBCT and optical properties acquired from DOT serve as a priori information for the subsequent BLT reconstruction. Phantoms were designed and procedures were developed to calibrate the CBCT, DOT/BLT, and the entire integrated system. Geometrical calibration was performed to calibrate the CBCT system. Flat field correction was performed to correct the nonuniform response of the optical imaging system. Absolute emittance calibration was performed to convert the camera readout to the emittance at the phantom or animal surface, which enabled the direct reconstruction of the bioluminescence source strength. Phantom and mouse imaging were performed to validate the calibration. Results: All calibration procedures were successfully performed. Both CBCT of a thin wire and a euthanized mouse revealed no spatial artifact, validating the accuracy of the CBCT calibration. The absolute emittance calibration was validated with a 650 nm laser source, resulting in a 3

Systematic calibration of an integrated x-ray and optical tomography system for preclinical radiation research

International Nuclear Information System (INIS)

Yang, Yidong; Wang, Ken Kang-Hsin; Wong, John W.; Eslami, Sohrab; Iordachita, Iulian I.; Patterson, Michael S.

2015-01-01

Purpose: The cone beam computed tomography (CBCT) guided small animal radiation research platform (SARRP) has been developed for focal tumor irradiation, allowing laboratory researchers to test basic biological hypotheses that can modify radiotherapy outcomes in ways that were not feasible previously. CBCT provides excellent bone to soft tissue contrast, but is incapable of differentiating tumors from surrounding soft tissue. Bioluminescence tomography (BLT), in contrast, allows direct visualization of even subpalpable tumors and quantitative evaluation of tumor response. Integration of BLT with CBCT offers complementary image information, with CBCT delineating anatomic structures and BLT differentiating luminescent tumors. This study is to develop a systematic method to calibrate an integrated CBCT and BLT imaging system which can be adopted onboard the SARRP to guide focal tumor irradiation. Methods: The integrated imaging system consists of CBCT, diffuse optical tomography (DOT), and BLT. The anatomy acquired from CBCT and optical properties acquired from DOT serve as a priori information for the subsequent BLT reconstruction. Phantoms were designed and procedures were developed to calibrate the CBCT, DOT/BLT, and the entire integrated system. Geometrical calibration was performed to calibrate the CBCT system. Flat field correction was performed to correct the nonuniform response of the optical imaging system. Absolute emittance calibration was performed to convert the camera readout to the emittance at the phantom or animal surface, which enabled the direct reconstruction of the bioluminescence source strength. Phantom and mouse imaging were performed to validate the calibration. Results: All calibration procedures were successfully performed. Both CBCT of a thin wire and a euthanized mouse revealed no spatial artifact, validating the accuracy of the CBCT calibration. The absolute emittance calibration was validated with a 650 nm laser source, resulting in a 3

WE-H-206-01: Photoacoustic Tomography: Multiscale Imaging From Organelles to Patients by Ultrasonically Beating the Optical Diffusion Limit

International Nuclear Information System (INIS)

Wang, L.

2016-01-01

Lihong V. Wang: Photoacoustic tomography (PAT), combining non-ionizing optical and ultrasonic waves via the photoacoustic effect, provides in vivo multiscale functional, metabolic, and molecular imaging. Broad applications include imaging of the breast, brain, skin, esophagus, colon, vascular system, and lymphatic system in humans or animals. Light offers rich contrast but does not penetrate biological tissue in straight paths as x-rays do. Consequently, high-resolution pure optical imaging (e.g., confocal microscopy, two-photon microscopy, and optical coherence tomography) is limited to penetration within the optical diffusion limit (∼1 mm in the skin). Ultrasonic imaging, on the contrary, provides fine spatial resolution but suffers from both poor contrast in early-stage tumors and strong speckle artifacts. In PAT, pulsed laser light penetrates tissue and generates a small but rapid temperature rise, which induces emission of ultrasonic waves due to thermoelastic expansion. The ultrasonic waves, orders of magnitude less scattering than optical waves, are then detected to form high-resolution images of optical absorption at depths up to 7 cm, conquering the optical diffusion limit. PAT is the only modality capable of imaging across the length scales of organelles, cells, tissues, and organs (up to whole-body small animals) with consistent contrast. This rapidly growing technology promises to enable multiscale biological research and accelerate translation from microscopic laboratory discoveries to macroscopic clinical practice. PAT may also hold the key to label-free early detection of cancer by in vivo quantification of hypermetabolism, the quintessential hallmark of malignancy. Learning Objectives: To understand the contrast mechanism of PAT To understand the multiscale applications of PAT Benjamin M. W. Tsui: Multi-modality molecular imaging instrumentation and techniques have been major developments in small animal imaging that has contributed significantly

WE-H-206-01: Photoacoustic Tomography: Multiscale Imaging From Organelles to Patients by Ultrasonically Beating the Optical Diffusion Limit

Energy Technology Data Exchange (ETDEWEB)

Wang, L. [Washington University (United States)

2016-06-15

Lihong V. Wang: Photoacoustic tomography (PAT), combining non-ionizing optical and ultrasonic waves via the photoacoustic effect, provides in vivo multiscale functional, metabolic, and molecular imaging. Broad applications include imaging of the breast, brain, skin, esophagus, colon, vascular system, and lymphatic system in humans or animals. Light offers rich contrast but does not penetrate biological tissue in straight paths as x-rays do. Consequently, high-resolution pure optical imaging (e.g., confocal microscopy, two-photon microscopy, and optical coherence tomography) is limited to penetration within the optical diffusion limit (∼1 mm in the skin). Ultrasonic imaging, on the contrary, provides fine spatial resolution but suffers from both poor contrast in early-stage tumors and strong speckle artifacts. In PAT, pulsed laser light penetrates tissue and generates a small but rapid temperature rise, which induces emission of ultrasonic waves due to thermoelastic expansion. The ultrasonic waves, orders of magnitude less scattering than optical waves, are then detected to form high-resolution images of optical absorption at depths up to 7 cm, conquering the optical diffusion limit. PAT is the only modality capable of imaging across the length scales of organelles, cells, tissues, and organs (up to whole-body small animals) with consistent contrast. This rapidly growing technology promises to enable multiscale biological research and accelerate translation from microscopic laboratory discoveries to macroscopic clinical practice. PAT may also hold the key to label-free early detection of cancer by in vivo quantification of hypermetabolism, the quintessential hallmark of malignancy. Learning Objectives: To understand the contrast mechanism of PAT To understand the multiscale applications of PAT Benjamin M. W. Tsui: Multi-modality molecular imaging instrumentation and techniques have been major developments in small animal imaging that has contributed significantly

A cost-effective LED and photodetector based fast direct 3D diffuse optical imaging system

Science.gov (United States)

Saikia, Manob Jyoti; Manjappa, Rakesh; Kanhirodan, Rajan

2017-07-01

A cost-effective and high-speed 3D diffuse optical tomography system using high power LED light sources and silicon photodetectors has been designed and built, that can continuously scan and reconstruct spectroscopic images at a frame rate of 2 fps. The system is experimentally validated with tissue mimicking cylindrical resin phantom having light absorbing inhomogeneities of different size, shape and contrast, and at different locations.

Spatio-temporal imaging of the hemoglobin in the compressed breast with diffuse optical tomography

Science.gov (United States)

Boverman, Gregory; Fang, Qianqian; Carp, Stefan A.; Miller, Eric L.; Brooks, Dana H.; Selb, Juliette; Moore, Richard H.; Kopans, Daniel B.; Boas, David A.

2007-07-01

We develop algorithms for imaging the time-varying optical absorption within the breast given diffuse optical tomographic data collected over a time span that is long compared to the dynamics of the medium. Multispectral measurements allow for the determination of the time-varying total hemoglobin concentration and of oxygen saturation. To facilitate the image reconstruction, we decompose the hemodynamics in time into a linear combination of spatio-temporal basis functions, the coefficients of which are estimated using all of the data simultaneously, making use of a Newton-based nonlinear optimization algorithm. The solution of the extremely large least-squares problem which arises in computing the Newton update is obtained iteratively using the LSQR algorithm. A Laplacian spatial regularization operator is applied, and, in addition, we make use of temporal regularization which tends to encourage similarity between the images of the spatio-temporal coefficients. Results are shown for an extensive simulation, in which we are able to image and quantify localized changes in both total hemoglobin concentration and oxygen saturation. Finally, a breast compression study has been performed for a normal breast cancer screening subject, using an instrument which allows for highly accurate co-registration of multispectral diffuse optical measurements with an x-ray tomosynthesis image of the breast. We are able to quantify the global return of blood to the breast following compression, and, in addition, localized changes are observed which correspond to the glandular region of the breast.

Optical coherence tomography in conjunction with bronchoscopy

International Nuclear Information System (INIS)

Rodrigues, Ascedio Jose; Takimura, Celso Kiyochi; Lemos Neto, Pedro Alves; Figueiredo, Viviane Rossi

2012-01-01

To evaluate the feasibility of and the potential for using optical coherence tomography in conjunction with conventional bronchoscopy in the evaluation of the airways. Methods: This was a pilot study based on an ex vivo experimental model involving three animals: one adult New Zealand rabbit and two Landrace pigs. An optical coherence tomography imaging catheter was inserted through the working channel of a flexible bronchoscope in order to reach the distal trachea of the animals. Images of the walls of the trachea were systematically taken along its entire length, from the distal to the proximal portion. Results: The imaging catheter was easily adapted to the working channel of the bronchoscope. High-resolution images of cross sections of the trachea were taken in real time, precisely delineating microstructures, such as the epithelium, submucosa, and cartilage, as well as the adventitia of the anterior and lateral tracheal walls. The corresponding layers of the epithelium, mucosa, and cartilage were clearly differentiated. The mucosa, submucosa, and trachealis muscle were clearly identified in the posterior wall. Conclusions: It is feasible to use an optical coherence tomography imaging catheter in combination with a flexible bronchoscope. Optical coherence tomography produces high resolution images that reveal the microanatomy of the trachea, including structures that are typically seen only on images produced by conventional histology. (author)

Optical coherence tomography in conjunction with bronchoscopy

Energy Technology Data Exchange (ETDEWEB)

Rodrigues, Ascedio Jose; Takimura, Celso Kiyochi; Lemos Neto, Pedro Alves; Figueiredo, Viviane Rossi, E-mail: ascedio@gmail.com [Servico de Endoscopia Respiratoria, Hospital das Clinicas, Universidade de Sao Paulo (FM/USP), SP (Brazil)

2012-07-01

To evaluate the feasibility of and the potential for using optical coherence tomography in conjunction with conventional bronchoscopy in the evaluation of the airways. Methods: This was a pilot study based on an ex vivo experimental model involving three animals: one adult New Zealand rabbit and two Landrace pigs. An optical coherence tomography imaging catheter was inserted through the working channel of a flexible bronchoscope in order to reach the distal trachea of the animals. Images of the walls of the trachea were systematically taken along its entire length, from the distal to the proximal portion. Results: The imaging catheter was easily adapted to the working channel of the bronchoscope. High-resolution images of cross sections of the trachea were taken in real time, precisely delineating microstructures, such as the epithelium, submucosa, and cartilage, as well as the adventitia of the anterior and lateral tracheal walls. The corresponding layers of the epithelium, mucosa, and cartilage were clearly differentiated. The mucosa, submucosa, and trachealis muscle were clearly identified in the posterior wall. Conclusions: It is feasible to use an optical coherence tomography imaging catheter in combination with a flexible bronchoscope. Optical coherence tomography produces high resolution images that reveal the microanatomy of the trachea, including structures that are typically seen only on images produced by conventional histology. (author)

Temporal comparison of functional brain imaging with diffuse optical tomography and fMRI during rat forepaw stimulation

International Nuclear Information System (INIS)

Siegel, Andrew M; Culver, Joseph P; Mandeville, Joseph B; Boas, David A

2003-01-01

The time courses of oxyhaemoglobin ([HbO 2 ]), deoxyhaemoglobin ([HbR]) and total haemoglobin ([HbT]) concentration changes following cortical activation in rats by electrical forepaw stimulation were measured using diffuse optical tomography (DOT) and compared to similar measurements performed previously with fMRI at 2.0 T and 4.7 T. We also explored the qualitative effects of varying stimulus parameters on the temporal evolution of the hemodynamic response. DOT images were reconstructed at a depth of 1.5 mm over a 1 cm square area from 2 mm anterior to bregma to 8 mm posterior to bregma. The measurement set included 9 sources and 16 detectors with an imaging frame rate of 10 Hz. Both DOT [HbR] and [HbO 2 ] time courses were compared to the fMRI BOLD time course during stimulation, and the DOT [HbT] time course was compared to the fMRI cerebral plasma volume (CPV) time course. We believe that DOT and fMRI can provide similar temporal information for both blood volume and deoxyhaemoglobin changes, which helps to cross-validate these two techniques and to demonstrate that DOT can be useful as a complementary modality to fMRI for investigating the hemodynamic response to neuronal activity

Temporal comparison of functional brain imaging with diffuse optical tomography and fMRI during rat forepaw stimulation

Energy Technology Data Exchange (ETDEWEB)

Siegel, Andrew M [Tufts University Bioengineering Center, Medford, MA 02155 (United States); Culver, Joseph P [Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02129 (United States); Mandeville, Joseph B [Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02129 (United States); Boas, David A [Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02129 (United States)

2003-05-21

The time courses of oxyhaemoglobin ([HbO{sub 2}]), deoxyhaemoglobin ([HbR]) and total haemoglobin ([HbT]) concentration changes following cortical activation in rats by electrical forepaw stimulation were measured using diffuse optical tomography (DOT) and compared to similar measurements performed previously with fMRI at 2.0 T and 4.7 T. We also explored the qualitative effects of varying stimulus parameters on the temporal evolution of the hemodynamic response. DOT images were reconstructed at a depth of 1.5 mm over a 1 cm square area from 2 mm anterior to bregma to 8 mm posterior to bregma. The measurement set included 9 sources and 16 detectors with an imaging frame rate of 10 Hz. Both DOT [HbR] and [HbO{sub 2}] time courses were compared to the fMRI BOLD time course during stimulation, and the DOT [HbT] time course was compared to the fMRI cerebral plasma volume (CPV) time course. We believe that DOT and fMRI can provide similar temporal information for both blood volume and deoxyhaemoglobin changes, which helps to cross-validate these two techniques and to demonstrate that DOT can be useful as a complementary modality to fMRI for investigating the hemodynamic response to neuronal activity.

High-definition optical coherence tomography

DEFF Research Database (Denmark)

Boone, Marc; Norrenberg, Sarah; Jemec, Gregor

2013-01-01

to those described for reflectance confocal microscopy but with the advantages not only to visualize individual cells up to a depth of 570 μm but also in both slice and en face mode. An adapted algorithmic method for pattern analysis of common inflammatory skin diseases could be proposed. This new......High-definition optical coherence tomography (HD-OCT) is a non-invasive technique for morphological investigation of tissue with cellular resolution filling the imaging gap between reflectance confocal microscopy and conventional optical coherence tomography. The aim of this study is first...... dermatitis. Additional studies to test the sensitivity and specificity of the proposed algorithm for pattern analysis are essential. The other categories of Ackerman's pattern recognition need to be evaluated. This study provides a set of morphological features generated by HD-OCT imaging very similar...

In-line optical fiber metallic mirror reflector for monolithic common path optical coherence tomography probes.

Science.gov (United States)

Singh, Kanwarpal; Reddy, Rohith; Sharma, Gargi; Verma, Yogesh; Gardecki, Joseph A; Tearney, Guillermo

2018-03-01

Endoscopic optical coherence tomography probes suffer from various artifacts due to dispersion imbalance and polarization mismatch between reference and sample arm light. Such artifacts can be minimized using a common path approach. In this work, we demonstrate a miniaturized common path probe for optical coherence tomography using an inline fiber mirror. A common path optical fiber probe suitable for performing high-resolution endoscopic optical coherence tomography imaging was developed. To achieve common path functionality, an inline fiber mirror was fabricated using a thin gold layer. A commercially available swept source engine was used to test the designed probe in a cadaver human coronary artery ex vivo. We achieved a sensitivity of 104 dB for this probe using a swept source optical coherence tomography system. To test the probe, images of a cadaver human coronary artery were obtained, demonstrating the quality that is comparable to those obtained by OCT systems with separate reference arms. Additionally, we demonstrate recovery of ranging depth by use of a Michelson interferometer in the detection path. We developed a miniaturized monolithic inline fiber mirror-based common path probe for optical coherence tomography. Owing to its simplicity, our design will be helpful in endoscopic applications that require high-resolution probes in a compact form factor while reducing system complexity. Lasers Surg. Med. 50:230-235, 2018. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

An All-Fiber-Optic Combined System of Noncontact Photoacoustic Tomography and Optical Coherence Tomography.

Science.gov (United States)

Eom, Jonghyun; Shin, Jun Geun; Park, Soongho; Rim, Sunghwan; Lee, Byeong Ha

2016-05-20

We propose an all-fiber-based dual-modal imaging system that combines noncontact photoacoustic tomography (PAT) and optical coherence tomography (OCT). The PAT remotely measures photoacoustic (PA) signals with a 1550-nm laser on the surface of a sample by utilizing a fiber interferometer as an ultrasound detector. The fiber-based OCT, employing a swept-source laser centered at 1310 nm, shares the sample arm of the PAT system. The fiber-optic probe for the combined system was homemade with a lensed single-mode fiber (SMF) and a large-core multimode fiber (MMF). The compact and robust common probe is capable of obtaining both the PA and the OCT signals at the same position without any physical contact. Additionally, the MMF of the probe delivers the short pulses of a Nd:YAG laser to efficiently excite the PA signals. We experimentally demonstrate the feasibility of the proposed dual-modal system with a phantom made of a fishing line and a black polyethylene terephthalate fiber in a tissue mimicking solution. The all-fiber-optic system, capable of providing complementary information about absorption and scattering, has a promising potential in minimally invasive and endoscopic imaging.

An All-Fiber-Optic Combined System of Noncontact Photoacoustic Tomography and Optical Coherence Tomography

Science.gov (United States)

Eom, Jonghyun; Shin, Jun Geun; Park, Soongho; Rim, Sunghwan; Lee, Byeong Ha

2016-01-01

We propose an all-fiber-based dual-modal imaging system that combines noncontact photoacoustic tomography (PAT) and optical coherence tomography (OCT). The PAT remotely measures photoacoustic (PA) signals with a 1550-nm laser on the surface of a sample by utilizing a fiber interferometer as an ultrasound detector. The fiber-based OCT, employing a swept-source laser centered at 1310 nm, shares the sample arm of the PAT system. The fiber-optic probe for the combined system was homemade with a lensed single-mode fiber (SMF) and a large-core multimode fiber (MMF). The compact and robust common probe is capable of obtaining both the PA and the OCT signals at the same position without any physical contact. Additionally, the MMF of the probe delivers the short pulses of a Nd:YAG laser to efficiently excite the PA signals. We experimentally demonstrate the feasibility of the proposed dual-modal system with a phantom made of a fishing line and a black polyethylene terephthalate fiber in a tissue mimicking solution. The all-fiber-optic system, capable of providing complementary information about absorption and scattering, has a promising potential in minimally invasive and endoscopic imaging. PMID:27213392

An All-Fiber-Optic Combined System of Noncontact Photoacoustic Tomography and Optical Coherence Tomography

Directory of Open Access Journals (Sweden)

Jonghyun Eom

2016-05-01

Full Text Available We propose an all-fiber-based dual-modal imaging system that combines noncontact photoacoustic tomography (PAT and optical coherence tomography (OCT. The PAT remotely measures photoacoustic (PA signals with a 1550-nm laser on the surface of a sample by utilizing a fiber interferometer as an ultrasound detector. The fiber-based OCT, employing a swept-source laser centered at 1310 nm, shares the sample arm of the PAT system. The fiber-optic probe for the combined system was homemade with a lensed single-mode fiber (SMF and a large-core multimode fiber (MMF. The compact and robust common probe is capable of obtaining both the PA and the OCT signals at the same position without any physical contact. Additionally, the MMF of the probe delivers the short pulses of a Nd:YAG laser to efficiently excite the PA signals. We experimentally demonstrate the feasibility of the proposed dual-modal system with a phantom made of a fishing line and a black polyethylene terephthalate fiber in a tissue mimicking solution. The all-fiber-optic system, capable of providing complementary information about absorption and scattering, has a promising potential in minimally invasive and endoscopic imaging.

Atlas-based head modeling and spatial normalization for high-density diffuse optical tomography: in vivo validation against fMRI.

Science.gov (United States)

Ferradal, Silvina L; Eggebrecht, Adam T; Hassanpour, Mahlega; Snyder, Abraham Z; Culver, Joseph P

2014-01-15

Diffuse optical imaging (DOI) is increasingly becoming a valuable neuroimaging tool when fMRI is precluded. Recent developments in high-density diffuse optical tomography (HD-DOT) overcome previous limitations of sparse DOI systems, providing improved image quality and brain specificity. These improvements in instrumentation prompt the need for advancements in both i) realistic forward light modeling for accurate HD-DOT image reconstruction, and ii) spatial normalization for voxel-wise comparisons across subjects. Individualized forward light models derived from subject-specific anatomical images provide the optimal inverse solutions, but such modeling may not be feasible in all situations. In the absence of subject-specific anatomical images, atlas-based head models registered to the subject's head using cranial fiducials provide an alternative solution. In addition, a standard atlas is attractive because it defines a common coordinate space in which to compare results across subjects. The question therefore arises as to whether atlas-based forward light modeling ensures adequate HD-DOT image quality at the individual and group level. Herein, we demonstrate the feasibility of using atlas-based forward light modeling and spatial normalization methods. Both techniques are validated using subject-matched HD-DOT and fMRI data sets for visual evoked responses measured in five healthy adult subjects. HD-DOT reconstructions obtained with the registered atlas anatomy (i.e. atlas DOT) had an average localization error of 2.7mm relative to reconstructions obtained with the subject-specific anatomical images (i.e. subject-MRI DOT), and 6.6mm relative to fMRI data. At the group level, the localization error of atlas DOT reconstruction was 4.2mm relative to subject-MRI DOT reconstruction, and 6.1mm relative to fMRI. These results show that atlas-based image reconstruction provides a viable approach to individual head modeling for HD-DOT when anatomical imaging is not available

Serial Diffusion Tensor Imaging of the Optic Radiations after Acute Optic Neuritis

Directory of Open Access Journals (Sweden)

Scott C. Kolbe

2016-01-01

Full Text Available Previous studies have reported diffusion tensor imaging (DTI changes within the optic radiations of patients after optic neuritis (ON. We aimed to study optic radiation DTI changes over 12 months following acute ON and to study correlations between DTI parameters and damage to the optic nerve and primary visual cortex (V1. We measured DTI parameters [fractional anisotropy (FA, axial diffusivity (AD, radial diffusivity (RD, and mean diffusivity (MD] from the optic radiations of 38 acute ON patients at presentation and 6 and 12 months after acute ON. In addition, we measured retinal nerve fibre layer thickness, visual evoked potential amplitude, optic radiation lesion load, and V1 thickness. At baseline, FA was reduced and RD and MD were increased compared to control. Over 12 months, FA reduced in patients at an average rate of −2.6% per annum (control = −0.51%; p=0.006. Change in FA, RD, and MD correlated with V1 thinning over 12 months (FA: R=0.450, p=0.006; RD: R=-0.428, p=0.009; MD: R=-0.365, p=0.029. In patients with no optic radiation lesions, AD significantly correlated with RNFL thinning at 12 months (R=0.489, p=0.039. In conclusion, DTI can detect optic radiation changes over 12 months following acute ON that correlate with optic nerve and V1 damage.

INTRASURGICAL MICROSCOPE-INTEGRATED SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY-ASSISTED MEMBRANE PEELING.

Science.gov (United States)

Falkner-Radler, Christiane I; Glittenberg, Carl; Gabriel, Max; Binder, Susanne

2015-10-01

To evaluate microscope-integrated intrasurgical spectral domain optical coherence tomography during macular surgery in a prospective monocenter study. Before pars plana vitrectomy and before, during, and after membrane peeling, 512 × 128 macular cube scans were performed using a Carl Zeiss Meditec Cirrus high-definition OCT system adapted to the optical pathway of a Zeiss OPMI VISU 200 surgical microscope and compared with retinal staining. The study included 51 patients with epiretinal membranes, with 8 of those having additional lamellar macular holes, 11 patients with vitreomacular traction, and 8 patients with full-thickness macular holes. Intraoperative spectral domain optical coherence tomography allowed performing membrane peeling without using retinal dyes in 40% of cases (28 of 70 patients). No residual membranes were found in 94.3% of patients (66 of 70 patients) in intrasurgical spectral domain optical coherence tomography and subsequent (re)staining. In patients with vitreomacular traction, intrasurgical spectral domain optical coherence tomography scans facilitated decisions on the need for an intraocular tamponade after membrane peeling. Intraoperative spectral domain optical coherence tomography was comparable with retinal dyes in confirming success after membrane peeling. However, the visualization of flat membranes was better after staining.

Computed tomography in orbital fractures and optic nerve trauma

International Nuclear Information System (INIS)

Dietrich, U.; Sievers, K.; Feldges, A.; Nau, H.E.

1990-01-01

Ten patients with orbital fractures and optic nerve trauma are reported. Fractures of the optic canal could be demonstrated by computed tomography in six cases and fractures of the orbital apex in another three cases. Surgical decompression of the optic canal was performed in seven cases. Computed tomography enhanced decision for surgery in cases of intraorbital haematoma with exophthalmus and narrowing of the canal by bony fragments, especially in those patients presenting with incomplete or progressive visual disturbance. (orig.) [de

Three-dimensional multifunctional optical coherence tomography for skin imaging

Science.gov (United States)

Li, En; Makita, Shuichi; Hong, Young-Joo; Kasaragod, Deepa; Sasaoka, Tomoko; Yamanari, Masahiro; Sugiyama, Satoshi; Yasuno, Yoshiaki

2016-02-01

Optical coherence tomography (OCT) visualizes cross-sectional microstructures of biological tissues. Recent developments of multifunctional OCT (MF-OCT) provides multiple optical contrasts which can reveal currently unknown tissue properties. In this contribution we demonstrate multifunctional OCT specially designed for dermatological investigation. And by utilizing it to measure four different body parts of in vivo human skin, three-dimensional scattering OCT, OCT angiography, polarization uniformity tomography, and local birefringence tomography images were obtained by a single scan. They respectively contrast the structure and morphology, vasculature, melanin content and collagen traits of the tissue.

Optical coherence tomography of basal cell carcinoma

DEFF Research Database (Denmark)

Yücel, D.; Themstrup, L.; Manfredi, Maddalena

2016-01-01

Background: Basal cell carcinoma (BCC) is the most prevalent malignancy in Caucasians. Optical coherence tomography (OCT) is a non-invasive optical imaging technology using the principle of interferometry. OCT has shown a great potential in diagnosing, monitoring, and follow-up of BCC. So far most...

Quantitative imaging of cerebral blood flow velocity and intracellular motility using dynamic light scattering-optical coherence tomography.

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Lee, Jonghwan; Radhakrishnan, Harsha; Wu, Weicheng; Daneshmand, Ali; Climov, Mihail; Ayata, Cenk; Boas, David A

2013-06-01

This paper describes a novel optical method for label-free quantitative imaging of cerebral blood flow (CBF) and intracellular motility (IM) in the rodent cerebral cortex. This method is based on a technique that integrates dynamic light scattering (DLS) and optical coherence tomography (OCT), named DLS-OCT. The technique measures both the axial and transverse velocities of CBF, whereas conventional Doppler OCT measures only the axial one. In addition, the technique produces a three-dimensional map of the diffusion coefficient quantifying nontranslational motions. In the DLS-OCT diffusion map, we observed high-diffusion spots, whose locations highly correspond to neuronal cell bodies and whose diffusion coefficient agreed with that of the motion of intracellular organelles reported in vitro in the literature. Therefore, the present method has enabled, for the first time to our knowledge, label-free imaging of the diffusion-like motion of intracellular organelles in vivo. As an example application, we used the method to monitor CBF and IM during a brief ischemic stroke, where we observed an induced persistent reduction in IM despite the recovery of CBF after stroke. This result supports that the IM measured in this study represent the cellular energy metabolism-related active motion of intracellular organelles rather than free diffusion of intracellular macromolecules.

The Development, Commercialization, and Impact of Optical Coherence Tomography.

Science.gov (United States)

Fujimoto, James; Swanson, Eric

2016-07-01

This review was written for the special issue of IOVS to describe the history of optical coherence tomography (OCT) and its evolution from a nonscientific, historic perspective. Optical coherence tomography has become a standard of care in ophthalmology, providing real-time information on structure and function - diagnosing disease, evaluating progression, and assessing response to therapy, as well as helping to understand disease pathogenesis and create new therapies. Optical coherence tomography also has applications in multiple clinical specialties, fundamental research, and manufacturing. We review the early history of OCT describing how research and development evolves and the important role of multidisciplinary collaboration and expertise. Optical coherence tomography had its origin in femtosecond optics, but used optical communications technologies and required advanced engineering for early OCT prototypes, clinical feasibility studies, entrepreneurship, and corporate development in order to achieve clinical acceptance and clinical impact. Critical advances were made by early career researchers, clinician scientists, engineering experts, and business leaders, which enabled OCT to have a worldwide impact on health care. We introduce the concept of an "ecosystem" consisting of research, government funding, collaboration and competition, clinical studies, innovation, entrepreneurship and industry, and impact - all of which must work synergistically. The process that we recount is long and challenging, but it is our hope that it might inspire early career professionals in science, engineering, and medicine, and that the clinical and research community will find this review of interest.

The Development, Commercialization, and Impact of Optical Coherence Tomography

Science.gov (United States)

Fujimoto, James; Swanson, Eric

2016-01-01

This review was written for the special issue of IOVS to describe the history of optical coherence tomography (OCT) and its evolution from a nonscientific, historic perspective. Optical coherence tomography has become a standard of care in ophthalmology, providing real-time information on structure and function – diagnosing disease, evaluating progression, and assessing response to therapy, as well as helping to understand disease pathogenesis and create new therapies. Optical coherence tomography also has applications in multiple clinical specialties, fundamental research, and manufacturing. We review the early history of OCT describing how research and development evolves and the important role of multidisciplinary collaboration and expertise. Optical coherence tomography had its origin in femtosecond optics, but used optical communications technologies and required advanced engineering for early OCT prototypes, clinical feasibility studies, entrepreneurship, and corporate development in order to achieve clinical acceptance and clinical impact. Critical advances were made by early career researchers, clinician scientists, engineering experts, and business leaders, which enabled OCT to have a worldwide impact on health care. We introduce the concept of an “ecosystem” consisting of research, government funding, collaboration and competition, clinical studies, innovation, entrepreneurship and industry, and impact – all of which must work synergistically. The process that we recount is long and challenging, but it is our hope that it might inspire early career professionals in science, engineering, and medicine, and that the clinical and research community will find this review of interest. PMID:27409459

US-guided diffuse optical tomography for breast lesions: the reliability of clinical experience

Energy Technology Data Exchange (ETDEWEB)

Kim, Min Jung; Kim, Ji Youn; Youn, Jung Hyun; Kim, Myung Hyun; Koo, Hye Ryoung; Kim, Soo Jin; Sohn, Yu-Mee; Moon, Hee Jung; Kim, Eun-Kyung [Yonsei University College of Medicine, Institute of Radiological Science, Seoul (Korea, Republic of); Yonsei University College of Medicine, Department of Radiology, Seoul (Korea, Republic of)

2011-07-15

To prospectively assess the reliability of US-guided diffuse optical tomography (US-DOT) using interobserver agreement for the diagnosis of breast lesions with individual real-time imaging and to assess the interobserver agreement of conventional sonography (US) combined with US-DOT for differentiation between benignity and malignancy breast lesions. An Institutional Review Board approved this study, and all subjects provided written informed consent. 122 breast lesions in 111 patients evaluated with US-guided core biopsy were included. Assessments with US and US-DOT for cases subjected to biopsy were obtained by two radiologists using individual real-time imaging prior to biopsy and were prospectively recorded by each performer. With DOT, the total haemoglobin concentration (THC) for each breast lesion was measured. Histopathological results from US-guided biopsies were used as a reference standard. To assess measurement interobserver agreement, the intraclass correlation coefficient (ICC) and the Bland-Altman plot were used for THC in US-DOT and the kappa values and ROC analysis were used to evaluate the diagnostic performances of the US BI-RADS final assessment in US and combined US and US-DOT. Of 122 US-guided core biopsied lesions, 83 (68.0%) were diagnosed as benign, and 39 (32.0%) as malignant. Excellent correlation was seen in the THC in US-DOT (ICC score 0.796; 95% confidence interval, 0.708-0.857). The interobserver agreement in BI-RADS final assessment with US and US-DOT (almost perfect; {kappa} = 0.8618) was improved compared with that of US (substantial agreement, {kappa} = 0.6574). However, the overall areas under the ROC curve did not show significant differences between US and combined US and US-DOT, 0.8894 and 0.8975, respectively (P = 0.981). The reliability of THC in US-DOT showed excellent correlation in overall real-time performance. Although the inter-observer agreement for BI-RADS final assessment of US was improved by using US-DOT, the

Hyperspectral optical tomography of intrinsic signals in the rat cortex

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Konecky, Soren D.; Wilson, Robert H.; Hagen, Nathan; Mazhar, Amaan; Tkaczyk, Tomasz S.; Frostig, Ron D.; Tromberg, Bruce J.

2015-01-01

Abstract. We introduce a tomographic approach for three-dimensional imaging of evoked hemodynamic activity, using broadband illumination and diffuse optical tomography (DOT) image reconstruction. Changes in diffuse reflectance in the rat somatosensory cortex due to stimulation of a single whisker were imaged at a frame rate of 5 Hz using a hyperspectral image mapping spectrometer. In each frame, images in 38 wavelength bands from 484 to 652 nm were acquired simultaneously. For data analysis, we developed a hyperspectral DOT algorithm that used the Rytov approximation to quantify changes in tissue concentration of oxyhemoglobin (ctHbO2) and deoxyhemoglobin (ctHb) in three dimensions. Using this algorithm, the maximum changes in ctHbO2 and ctHb were found to occur at 0.29±0.02 and 0.66±0.04  mm beneath the surface of the cortex, respectively. Rytov tomographic reconstructions revealed maximal spatially localized increases and decreases in ctHbO2 and ctHb of 321±53 and 555±96  nM, respectively, with these maximum changes occurring at 4±0.2  s poststimulus. The localized optical signals from the Rytov approximation were greater than those from modified Beer–Lambert, likely due in part to the inability of planar reflectance to account for partial volume effects. PMID:26835483

Analysis of radiation fields in tomography on diffusion gaseous sound

International Nuclear Information System (INIS)

Bekman, I.N.

1999-01-01

Perspectives of application of equilibrium and stationary variants of diffusion tomography with radioactive gaseous sounds for spatial reconstruction of heterogeneous media in materials technology were considered. The basic attention were allocated to creation of simple algorithms of detection of sound accumulation on the background of monotonically varying concentration field. Algorithms of transformation of two-dimensional radiation field in three-dimensional distribution of radiation sources were suggested. The methods of analytical elongation of concentration field permitting separation of regional anomalies on the background of local ones and vice verse were discussed. It was shown that both equilibrium and stationary variants of diffusion tomography detect the heterogeneity of testing material, provide reduction of spatial distribution of elements of its structure and give an estimation of relative degree of defectiveness

Characterization of dynamic physiology of the bladder by optical coherence tomography

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Yuan, Zhijia; Keng, Kerri; Pan, Rubin; Ren, Hugang; Du, Congwu; Kim, Jason; Pan, Yingtian

2012-03-01

Because of its high spatial resolution and noninvasive imaging capabilities, optical coherence tomography has been used to characterize the morphological details of various biological tissues including urinary bladder and to diagnose their alternations (e.g., cancers). In addition to static morphology, the dynamic features of tissue morphology can provide important information that can be used to diagnose the physiological and functional characteristics of biological tissues. Here, we present the imaging studies based on optical coherence tomography to characterize motion related physiology and functions of rat bladder detrusor muscles and compared the results with traditional biomechanical measurements. Our results suggest that optical coherence tomography is capable of providing quantitative evaluation of contractile functions of intact bladder (without removing bladder epithelium and connective tissue), which is potentially of more clinical relevance for future clinical diagnosis - if incorporated with cystoscopic optical coherence tomography.

Singular value decomposition metrics show limitations of detector design in diffuse fluorescence tomography.

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Leblond, Frederic; Tichauer, Kenneth M; Pogue, Brian W

2010-11-29

The spatial resolution and recovered contrast of images reconstructed from diffuse fluorescence tomography data are limited by the high scattering properties of light propagation in biological tissue. As a result, the image reconstruction process can be exceedingly vulnerable to inaccurate prior knowledge of tissue optical properties and stochastic noise. In light of these limitations, the optimal source-detector geometry for a fluorescence tomography system is non-trivial, requiring analytical methods to guide design. Analysis of the singular value decomposition of the matrix to be inverted for image reconstruction is one potential approach, providing key quantitative metrics, such as singular image mode spatial resolution and singular data mode frequency as a function of singular mode. In the present study, these metrics are used to analyze the effects of different sources of noise and model errors as related to image quality in the form of spatial resolution and contrast recovery. The image quality is demonstrated to be inherently noise-limited even when detection geometries were increased in complexity to allow maximal tissue sampling, suggesting that detection noise characteristics outweigh detection geometry for achieving optimal reconstructions.

[Fluorescein angiography and optical coherence tomography findings in central fundus of myopic patients].

Science.gov (United States)

Avetisov, S E; Budzinskaya, M V; Zhabina, O A; Andreeva, I V; Plyukhova, A A; Kobzova, M V; Musaeva, G M

2015-01-01

Myopia prevalence grows alike in many countries, including Russia, regardless of geographical and population conditions. to assess fundus changes in myopic patients at different ocular axial lengths by means of modern diagnostic tools. The study enrolled 97 patients (194 eyes) aged 45 ± 20.17 years with myopia of different degrees. Besides a standard ophthalmic examination, all patients underwent fundus fluorescein angiography and optical coherence tomography. The occurrence of retinal pigment epithelium (RPE) atrophy (diffuse or focal) has been shown to increase with increasing ocular axial length. Only 27 eyes (28.1%) appeared intact. As myopia progression implies axial growth of the eye, it is associated with a more severe decrease in choroid, RPE, and photoreceptor layer thicknesses: the longer the anterior-posterior axis, the thinner the above mentioned fundus structures. Age-related changes in the fundus are also likely to be more pronounced in longer axes. Myopic traction maculopathy, which in our case appeared the main cause of increased retinal thickness, was diagnosed in 105 eyes, "outer" macular retinoschisis--in 40 eyes. Thus, modern diagnostic tools, such as fluorescein angiography and optical coherence tomography, enable objective assessment of the central fundus.

Optical coherence tomography angiography in age-related macular degeneration: The game changer.

Science.gov (United States)

Lupidi, Marco; Cerquaglia, Alessio; Chhablani, Jay; Fiore, Tito; Singh, Sumit Randhir; Cardillo Piccolino, Felice; Corbucci, Roberta; Coscas, Florence; Coscas, Gabriel; Cagini, Carlo

2018-04-01

Optical coherence tomography angiography is one of the biggest advances in ophthalmic imaging. It enables a depth-resolved assessment of the retinal and choroidal blood flow, far exceeding the levels of detail commonly obtained with dye angiographies. One of the first applications of optical coherence tomography angiography was in detecting the presence of choroidal neovascularization in age-related macular degeneration and establishing its position in relation to the retinal pigmented epithelium and Bruch's membrane, and thereby classifying the CNV as type 1, type 2, type 3, or mixed lesions. Optical coherence tomography angiograms, due to the longer wavelength used by optical coherence tomography, showed a more distinct choroidal neovascularization vascular pattern than fluorescein angiography, since there is less suffering from light scattering or is less obscured by overlying subretinal hemorrhages or exudation. Qualitative and quantitative assessments of optical coherence tomography angiography findings in exudative and nonexudative age-related macular degeneration have been largely investigated within the past 3 years both in clinical and experimental settings. This review constitutes an up-to-date of all the potential applications of optical coherence tomography angiography in age-related macular degeneration in order to better understand how to translate its theoretical usefulness into the current clinical practice.

Solar tomography adaptive optics.

Science.gov (United States)

Ren, Deqing; Zhu, Yongtian; Zhang, Xi; Dou, Jiangpei; Zhao, Gang

2014-03-10

Conventional solar adaptive optics uses one deformable mirror (DM) and one guide star for wave-front sensing, which seriously limits high-resolution imaging over a large field of view (FOV). Recent progress toward multiconjugate adaptive optics indicates that atmosphere turbulence induced wave-front distortion at different altitudes can be reconstructed by using multiple guide stars. To maximize the performance over a large FOV, we propose a solar tomography adaptive optics (TAO) system that uses tomographic wave-front information and uses one DM. We show that by fully taking advantage of the knowledge of three-dimensional wave-front distribution, a classical solar adaptive optics with one DM can provide an extra performance gain for high-resolution imaging over a large FOV in the near infrared. The TAO will allow existing one-deformable-mirror solar adaptive optics to deliver better performance over a large FOV for high-resolution magnetic field investigation, where solar activities occur in a two-dimensional field up to 60'', and where the near infrared is superior to the visible in terms of magnetic field sensitivity.

All-optically integrated photoacoustic and optical coherence tomography: A review

Directory of Open Access Journals (Sweden)

Wei Qiao

2017-07-01

Full Text Available All-optically integrated photoacoustic (PA and optical coherence tomography (OCT dual-mode imaging technology that could offer comprehensive pathological information for accurate diagnosis in clinic has gradually become a promising imaging technology in the aspect of biomedical imaging during the recent years. This review refers to the technology aspects of all-optical PA detection and system evolution of optically integrated PA and OCT, including Michelson interferometer dual-mode imaging system, Fabry–Perot (FP interferometer dual-mode imaging system and Mach–Zehnder interferometer dual-mode imaging system. It is believed that the optically integrated PA and OCT has great potential applications in biomedical imaging.

[Evaluation of diabetic microangiopathy using optical coherence tomography angiography].

Science.gov (United States)

Czakó, Cecília; Sándor, Gábor László; Ecsedy, Mónika; Szepessy, Zsuzsanna; Borbándy, Ágnes; Resch, Miklós; Papp, András; Récsán, Zsuzsa; Horváth, Hajnalka; Nagy, Zoltán Zsolt; Kovács, Illés

2018-02-01

Optical coherence tomography angiography is a non-invasive imaging technique that is able to visualize the different retinal vascular layers using motion contrast to detect blood flow without intravenous dye injection. This method might help to assess microangiopathy in diabetic retinopathy during screening and follow-up. To quantify retinal microvasculature alterations in both eyes of diabetic patients in relation to systemic risk factors using optical coherence tomography angiography. Both eyes of 36 diabetic patients and 45 individuals without diabetes were examined. Duration of diabetes, insulin therapy, blood pressure, HbA 1c , dyslipidemia, axial length and the presence of diabetic retinopathy were recorded. Retinal vessel density was measured by optical coherence tomography angiography. The effect of risk factors on vessel density and between-eye asymmetry was assessed using multivariable regression analysis. Vessel density was significantly lower and between-eye difference was significantly higher in diabetic patients compared to controls (pdiabetes duration (pdiabetic retinopathy compared to control subjects (pdiabetes compared to healthy subjects. By using optical coherence tomography angiography, the detection of these microvascular alterations is possible before clinically detectable diabetic retinopathy and might serve as a useful tool in both screening and timing of treatment. Orv Hetil. 2018; 159(8): 320-326.

Optical Coherence Tomography Angiography of Retinal Cavernous Hemangioma.

Science.gov (United States)

Pierro, Luisa; Marchese, Alessandro; Gagliardi, Marco; Bandello, Francesco

2017-08-01

Retinal cavernous hemangioma is a rare, benign, retinal tumor characterized by angiomatous proliferation of vessels within the inner retina or the optic disc.1 Here we report a case of retinal cavernous hemangioma on the margin of the optic disc in the right eye of a 61-year-old asymptomatic female. The lesion was studied with multimodal imaging which included structural optical coherence tomography, fluorescein angiography, blue fundus auto-fluorescence, optical coherence tomography angiography (OCTA) (DRI OCT Triton; Topcon, Tokyo, Japan) and visual field examination. Blood circulation inside retinal cavernous hemangioma lesion is typically low-stagnant.2 However, OCTA demonstrated blood flow inside the lesion, illustrating its vascular circulation.3 Visual field was within the normal limits, except from a slight enlargement of the blind spot. [Ophthalmic Surg Lasers Imaging Retina. 2017;48:684-685.]. Copyright 2017, SLACK Incorporated.

Acute Solar Retinopathy Imaged With Adaptive Optics, Optical Coherence Tomography Angiography, and En Face Optical Coherence Tomography.

Science.gov (United States)

Wu, Chris Y; Jansen, Michael E; Andrade, Jorge; Chui, Toco Y P; Do, Anna T; Rosen, Richard B; Deobhakta, Avnish

2018-01-01

Solar retinopathy is a rare form of retinal injury that occurs after direct sungazing. To enhance understanding of the structural changes that occur in solar retinopathy by obtaining high-resolution in vivo en face images. Case report of a young adult woman who presented to the New York Eye and Ear Infirmary with symptoms of acute solar retinopathy after viewing the solar eclipse on August 21, 2017. Results of comprehensive ophthalmic examination and images obtained by fundus photography, microperimetry, spectral-domain optical coherence tomography (OCT), adaptive optics scanning light ophthalmoscopy, OCT angiography, and en face OCT. The patient was examined after viewing the solar eclipse. Visual acuity was 20/20 OD and 20/25 OS. The patient was left-eye dominant. Spectral-domain OCT images were consistent with mild and severe acute solar retinopathy in the right and left eye, respectively. Microperimetry was normal in the right eye but showed paracentral decreased retinal sensitivity in the left eye with a central absolute scotoma. Adaptive optics images of the right eye showed a small region of nonwaveguiding photoreceptors, while images of the left eye showed a large area of abnormal and nonwaveguiding photoreceptors. Optical coherence tomography angiography images were normal in both eyes. En face OCT images of the right eye showed a small circular hyperreflective area, with central hyporeflectivity in the outer retina of the right eye. The left eye showed a hyperreflective lesion that intensified in area from inner to middle retina and became mostly hyporeflective in the outer retina. The shape of the lesion on adaptive optics and en face OCT images of the left eye corresponded to the shape of the scotoma drawn by the patient on Amsler grid. Acute solar retinopathy can present with foveal cone photoreceptor mosaic disturbances on adaptive optics scanning light ophthalmoscopy imaging. Corresponding reflectivity changes can be seen on en face OCT, especially

Computerized tomography in diffuse diseases of the liver. Pt. 2

International Nuclear Information System (INIS)

Helmberger, H.; Vogel, U.; Bautz, W.

1993-01-01

Computerized tomography is a first-line method of imaging to confirm diffuse disorders of the liver suggested by preliminary clinical and biochemical findings. If the disease is caused by an obstructed vessel, this is reliably detected. For most types of thesaurismosis as well as hepatic steatosis and cirrhosis of the liver approaches to quantitative determinations of the spread of disease have been described in theory but so far failed to show great merits in practice. The transition from hepatic fibrosis to cirrhosis as the final developmental stage common to all those disorders has typical features on computerized tomography. This explains why the use of this method in diffuse hepatic disease offers particular advantages as regards the detection of complications occurring at an advanced stage ot the diagnosis of changes developing into malignancies. (orig.) [de

The relevance of light diffusion profiles for interstitial PDT using light-diffusing optical fibers

Science.gov (United States)

Stringasci, Mirian D.; Fortunato, Thereza C.; Moriyama, Lilian T.; Vollet Filho, José Dirceu; Bagnato, Vanderlei S.; Kurachi, Cristina

2017-02-01

Photodynamic therapy (PDT) is a technique used for several tumor types treatment. Light penetration on biological tissue is one limiting factor for PDT applied to large tumors. An alternative is using interstitial PDT, in which optical fibers are inserted into tumors. Cylindrical diffusers have been used in interstitial PDT. Light emission of different diffusers depends on the manufacturing process, size and optical properties of fibers, which make difficult to establish an adequate light dosimetry, since usually light profile is not designed for direct tissue-fiber contact. This study discusses the relevance of light distribution by a cylindrical diffuser into a turbid lipid emulsion solution, and how parts of a single diffuser contribute to illumination. A 2 cm-long cylindrical diffuser optical fiber was connected to a diode laser (630 nm), and the light spatial distribution was measured by scanning the solution with a collection probe. From the light field profile generated by a 1 mm-long intermediary element of a 20 mm-long cylindrical diffuser, recovery of light distribution for the entire diffuser was obtained. PDT was performed in rat healthy liver for a real treatment outcome analysis. By using computational tools, a typical necrosis profile generated by the irradiation with such a diffuser fiber was reconstructed. The results showed that it was possible predicting theoretically the shape of a necrosis profile in a healthy, homogeneous tissue with reasonable accuracy. The ability to predict the necrosis profile obtained from an interstitial illumination by optical diffusers has the potential improve light dosimetry for interstitial PDT.

Patch-based anisotropic diffusion scheme for fluorescence diffuse optical tomography—part 1: technical principles

International Nuclear Information System (INIS)

Correia, Teresa; Arridge, Simon

2016-01-01

Fluorescence diffuse optical tomography (fDOT) provides 3D images of fluorescence distributions in biological tissue, which represent molecular and cellular processes. The image reconstruction problem is highly ill-posed and requires regularisation techniques to stabilise and find meaningful solutions. Quadratic regularisation tends to either oversmooth or generate very noisy reconstructions, depending on the regularisation strength. Edge preserving methods, such as anisotropic diffusion regularisation (AD), can preserve important features in the fluorescence image and smooth out noise. However, AD has limited ability to distinguish an edge from noise. In this two-part paper, we propose a patch-based anisotropic diffusion regularisation (PAD), where regularisation strength is determined by a weighted average according to the similarity between patches around voxels within a search window, instead of a simple local neighbourhood strategy. However, this method has higher computational complexity and, hence, we wavelet compress the patches (PAD-WT) to speed it up, while simultaneously taking advantage of the denoising properties of wavelet thresholding. The proposed method combines the nonlocal means (NLM), AD and wavelet shrinkage methods, which are image processing methods. Therefore, in this first paper, we used a denoising test problem to analyse the performance of the new method. Our results show that the proposed PAD-WT method provides better results than the AD or NLM methods alone. The efficacy of the method for fDOT image reconstruction problem is evaluated in part 2. (paper)

Optical coherence tomography findings of quinine poisoning

Directory of Open Access Journals (Sweden)

John Christoforidis

2011-01-01

Full Text Available John Christoforidis, Robert Ricketts, Theodore Loizos, Susie ChangThe Ohio State University College of Medicine, Columbus, OH, USAPurpose: To report a case of acute quinine poisoning, document acute and chronic macular changes with optical coherence tomography imaging and fluorescein angiography (FA, and to review the literature on ocular toxicity of quinine.Methods: A 32-year-old white female presented to our Emergency Department after ingesting over 7.5 g of quinine. She underwent a complete ophthalmologic examination, fluorescein angiography, Stratus time-domain optical coherence tomography (OCT, and electroretinography at 72 hours and 15 months postingestion. Stratus time-domain and Cirrus spectral-domain OCT, fundus autofluorescence, and FA were obtained at 28 months postingestion.Results: Fluorescein angiography at 72 hours postingestion revealed normal filling times and vasculature. OCT showed marked thickening of the inner retina bilaterally. At 15 and 28 months follow-up, fundus photography and fluorescein angiography demonstrated optic nerve pallor, severely attenuated retinal vessels while OCT showed inner retinal atrophy. Fundus autofluorescence did not reveal any retinal pigmentary abnormalities.Conclusions: Quinine toxicity as seen by OCT reveals increased thickness with inner retinal hyperreflectivity acutely with development of significant retinal atrophy in the long-term. Fundus autofluorescence reveals an intact retinal pigment epithelial layer at 28 months. These findings suggest that quinine poisoning may produce a direct toxic effect on the inner retina in the acute phase resulting in long-term retinal atrophy.Keywords: retinal, optical coherence tomography, quinine toxicity 

Spectral domain optical coherence tomography findings in tamoxifen retinopathy--a case report.

Science.gov (United States)

Nair, Sandhya Narayanan; Anantharaman, Giridhar; Gopalakrishnan, Mahesh; Vyas, Jyothiprakash

2013-01-01

To report spectral domain optical coherence tomography findings in a case of typical tamoxifen retinopathy. In this observational case report, a patient with tamoxifen retinopathy was imaged with spectral domain optical coherence tomography and fundus auto fluorescence. Spectral domain optical coherence tomography showed numerous hyperreflective spots within the retina, mainly in the inner retinal layers in both the eyes. The external limiting membrane, the Inner Segment-Outer Segment junction, and the photoreceptors were not discernable at the fovea in the right eye. In the left eye, there was foveal atrophy with total loss of photoreceptors. The autofluorescent images showed macular hypofluorescence with foveal hyperfluorescence. Spectral domain optical coherence tomography demonstrated abnormalities in the outer retinal layers in tamoxifen retinopathy. There were also characteristic alterations in the autofluorescence pattern at the macula in tamoxifen retinopathy.

Diffusion tensor imaging of occult injury of optic radiation following optic neuritis in multiple sclerosis.

Science.gov (United States)

Chen, Jiafeng; Zhu, Lijun; Li, He; Lu, Ziwen; Chen, Xin; Fang, Shaokuan

2016-10-01

Multiple sclerosis (MS) is easily detected by routine magnetic resonance imaging (MRI). However, it is not possible to detect early or occult lesions in MS by routine MRI, and this may explain the inconsistency between the severity of the lesions found by MRI and the degree of clinical disability of patients with MS. The present study included 10 patients with relapsing-remitting MS and 10 healthy volunteers. Each patient underwent routine 3.0 T MRI, diffusion tensor imaging (DTI), and diffusion tensor tractography (DTT). Optic nerve and optic radiation were analyzed by DTI and DTT. The fractional anisotropy (FA), mean diffusivity (MD), λ // , and λ ┴ values were measured. In the 10 patients with MS, 7 optic nerves were affected, and 13 optic nerves were not affected. Cranial MRI showed that optic nerve thickening and hyperintensity occurred in 2 patients with MS. In the directionally encoded color maps, a hypointensive green signal in the optic nerve was observed in 3 patients with MS. The FA values were significantly lower and the MD, λ // , and λ ┴ values were significantly higher in the affected and unaffected optic nerves and optic radiations in patients with MS in comparison with controls (P0.05). Diffusion tensor imaging is sensitive in the detection of occult injury of the optic nerve and optic radiation following optic neuritis. Diffusion tensor imaging may be a useful tool for the early diagnosis, treatment and management of MS.

Diffusion MR Imaging of Postoperative Bilateral Acute Ischemic Optic Neuropathy

International Nuclear Information System (INIS)

Park, Ju Young; Lee, In Ho; Song, Chang June; Hwang, Hee Youn

2012-01-01

A 57-year-old woman experienced bilateral acute ischemic optic neuropathy after spine surgery. Routine MR imaging sequence, T2-weighted image, showed subtle high signal intensity on bilateral optic nerves. A contrast-enhanced T1 weighted image showed enhancement along the bilateral optic nerve sheath. Moreover, diffusion-weighted image (DWI) and an apparent diffusion coefficient map showed markedly restricted diffusion on bilateral optic nerves. Although MR findings of T2-weighted and contrast enhanced T1-weighted images may be nonspecific, the DWI finding of cytotoxic edema of bilateral optic nerves will be helpful for the diagnosis of acute ischemic optic neuropathy after spine surgery.

Diffusion MR Imaging of Postoperative Bilateral Acute Ischemic Optic Neuropathy

Energy Technology Data Exchange (ETDEWEB)

Park, Ju Young; Lee, In Ho; Song, Chang June [Chungnam National University Hospital, Daejeon (Korea, Republic of); Hwang, Hee Youn [Eulji University Hospital, Daejeon(Korea, Republic of)

2012-03-15

A 57-year-old woman experienced bilateral acute ischemic optic neuropathy after spine surgery. Routine MR imaging sequence, T2-weighted image, showed subtle high signal intensity on bilateral optic nerves. A contrast-enhanced T1 weighted image showed enhancement along the bilateral optic nerve sheath. Moreover, diffusion-weighted image (DWI) and an apparent diffusion coefficient map showed markedly restricted diffusion on bilateral optic nerves. Although MR findings of T2-weighted and contrast enhanced T1-weighted images may be nonspecific, the DWI finding of cytotoxic edema of bilateral optic nerves will be helpful for the diagnosis of acute ischemic optic neuropathy after spine surgery.

Optical coherent tomography in diagnoses of peripheral retinal degenarations

Directory of Open Access Journals (Sweden)

O. G. Pozdeyeva

2013-01-01

Full Text Available Purpose: Studying the capabilities of optical coherence tomography (RTVue-100, OPTOVUE, USA in evaluation of peripheral retinal degenerations, vitreoretinal adhesions, adjacent vitreous body as well as measurement of morphometric data.Methods: The study included 189 patients (239 eyes with peripheral retinal degeneration. 77 men and 112 women aged 18 to 84 underwent an ophthalmologic examination since November 2012 until October 2013. The peripheral retina was visualized with the help of optical coherence tomography («RTVue-100,» USA. The fundography was carried out using a Nikon NF505‑AF (Japan fundus camera. All patients were examined with a Goldmann lens.Results: Optical coherence tomography was used to evaluate different kinds of peripheral retinal degenerations, such as lattice and snail track degeneration, isolated retinal tears, cystoid retinal degeneration, pathological hyperpigmentation, retinoschisis and cobblestone degeneration. The following morphometric data were studied: dimensions of the lesion (average length, retinal thickness along the edge of the lesion, retinal thickness at the base of the lesion and the vitreoretinal interface.Conclusion: Optical coherence tomography is a promising in vivo visualization method which is useful in evaluation of peripheral retinal degenerations, vitreoretinal adhesions and tractions. It also provides a comprehensive protocolling system and monitoring. It will enable ophthalmologists to better define laser and surgical treatment indications and evaluate therapy effectiveness.

Optical coherent tomography in diagnoses of peripheral retinal degenarations

Directory of Open Access Journals (Sweden)

O. G. Pozdeyeva

2014-07-01

Full Text Available Purpose: Studying the capabilities of optical coherence tomography (RTVue-100, OPTOVUE, USA in evaluation of peripheral retinal degenerations, vitreoretinal adhesions, adjacent vitreous body as well as measurement of morphometric data.Methods: The study included 189 patients (239 eyes with peripheral retinal degeneration. 77 men and 112 women aged 18 to 84 underwent an ophthalmologic examination since November 2012 until October 2013. The peripheral retina was visualized with the help of optical coherence tomography («RTVue-100,» USA. The fundography was carried out using a Nikon NF505‑AF (Japan fundus camera. All patients were examined with a Goldmann lens.Results: Optical coherence tomography was used to evaluate different kinds of peripheral retinal degenerations, such as lattice and snail track degeneration, isolated retinal tears, cystoid retinal degeneration, pathological hyperpigmentation, retinoschisis and cobblestone degeneration. The following morphometric data were studied: dimensions of the lesion (average length, retinal thickness along the edge of the lesion, retinal thickness at the base of the lesion and the vitreoretinal interface.Conclusion: Optical coherence tomography is a promising in vivo visualization method which is useful in evaluation of peripheral retinal degenerations, vitreoretinal adhesions and tractions. It also provides a comprehensive protocolling system and monitoring. It will enable ophthalmologists to better define laser and surgical treatment indications and evaluate therapy effectiveness.

Diagnosis of malignant tumors of female breast cancer by transmission optical tomography

Directory of Open Access Journals (Sweden)

I. V. Pyanov

2012-01-01

Full Text Available A review of the literature on diagnostic systems for the detection of breast cancer by optical tomography was presented. The actuality of the method of transmission of optical tomography and its advantages over existing methods of medical diagnosis of cancer have been substanti- ated. We have analyzed tomographic systems used for the diagnosis of breast cancer. The basic advantages and disadvantages of tomograph- ic systems using various types of radiation have been indicated. The results of review can be used in the development of technique for optical transmission tomography.

Comparison of optic area measurement using fundus photography and optical coherence tomography between optic nerve head drusen and control subjects.

Science.gov (United States)

Flores-Rodríguez, Patricia; Gili, Pablo; Martín-Ríos, María Dolores; Grifol-Clar, Eulalia

2013-03-01

To compare optic disc area measurement between optic nerve head drusen (ONHD) and control subjects using fundus photography, time-domain optical coherence tomography (TD-OCT) and spectral-domain optical coherence tomography (SD-OCT). We also made a comparison between each of the three techniques. We performed our study on 66 eyes (66 patients) with ONHD and 70 healthy control subjects (70 controls) with colour ocular fundus photography at 20º (Zeiss FF 450 IR plus), TD-OCT (Stratus OCT) with the Fast Optic Disc protocol and SD-OCT (Cirrus OCT) with the Optic Disc Cube 200 × 200 protocol for measurement of the optic disc area. The measurements were made by two observers and in each measurement a correction of the image magnification factor was performed. Measurement comparison using the Student's t-test/Mann-Whitney U test, the intraclass correlation coefficient, Pearson/Spearman rank correlation coefficient and the Bland-Altman plot was performed in the statistical analysis. Mean and standard deviation (SD) of the optic disc area in ONHD and in controls was 2.38 (0.54) mm(2) and 2.54 (0.42) mm(2), respectively with fundus photography; 2.01 (0.56) mm(2) and 1.66 (0.37) mm(2), respectively with TD-OCT, and 2.03 (0.49) mm(2) and 1.75 (0.38) mm(2), respectively with SD-OCT. In ONHD and controls, repeatability of optic disc area measurement was excellent with fundus photography and optical coherence tomography (TD-OCT and SD-OCT), but with a low degree of agreement between both techniques. Optic disc area measurement is smaller in ONHD compared to healthy subjects with fundus photography, unlike time-domain and spectral-domain optical coherence tomography in which the reverse is true. Both techniques offer good repeatability, but a low degree of correlation and agreement, which means that optic disc area measurement is not interchangeable or comparable between techniques. Ophthalmic & Physiological Optics © 2013 The College of Optometrists.

Linear image reconstruction for a diffuse optical mammography system in a noncompressed geometry using scattering fluid

International Nuclear Information System (INIS)

Nielsen, Tim; Brendel, Bernhard; Ziegler, Ronny; Beek, Michiel van; Uhlemann, Falk; Bontus, Claas; Koehler, Thomas

2009-01-01

Diffuse optical tomography (DOT) is a potential new imaging modality to detect or monitor breast lesions. Recently, Philips developed a new DOT system capable of transmission and fluorescence imaging, where the investigated breast is hanging freely into the measurement cup containing scattering fluid. We present a fast and robust image reconstruction algorithm that is used for the transmission measurements. The algorithm is based on the Rytov approximation. We show that this algorithm can be used over a wide range of tissue optical properties if the reconstruction is adapted to each patient. We use estimates of the breast shape and average tissue optical properties to initialize the reconstruction, which improves the image quality significantly. We demonstrate the capability of the measurement system and reconstruction to image breast lesions by clinical examples

Reconstructions in ultrasound modulated optical tomography

KAUST Repository

Allmaras, Moritz; Bangerth, Wolfgang

2011-01-01

We introduce a mathematical model for ultrasound modulated optical tomography and present a simple reconstruction scheme for recovering the spatially varying optical absorption coefficient from scanning measurements with narrowly focused ultrasound signals. Computational results for this model show that the reconstruction of sharp features of the absorption coefficient is possible. A formal linearization of the model leads to an equation with a Fredholm operator, which explains the stability observed in our numerical experiments. © de Gruyter 2011.

Towards spectral-domain optical coherence tomography on a silicon chip

NARCIS (Netherlands)

Akça, B.I.; Worhoff, Kerstin; Nguyen, V.D.; Kalkman, J.; van Leeuwen, Ton; de Ridder, R.M.; Pollnau, Markus

Optical coherence tomography (OCT) is a widely used optical imaging technology, particularly in the medical field, since it can provide non-invasive, sub-micrometer resolution diagnostic images of tissue. Current OCT systems contain optical fibers and free-space optical components which make these

Fourier diffraction theorem for diffusion-based thermal tomography

International Nuclear Information System (INIS)

Baddour, Natalie

2006-01-01

There has been much recent interest in thermal imaging as a method of non-destructive testing and for non-invasive medical imaging. The basic idea of applying heat or cold to an area and observing the resulting temperature change with an infrared camera has led to the development of rapid and relatively inexpensive inspection systems. However, the main drawback to date has been that such an approach provides mainly qualitative results. In order to advance the quantitative results that are possible via thermal imaging, there is interest in applying techniques and algorithms from conventional tomography. Many tomography algorithms are based on the Fourier diffraction theorem, which is inapplicable to thermal imaging without suitable modification to account for the attenuative nature of thermal waves. In this paper, the Fourier diffraction theorem for thermal tomography is derived and discussed. The intent is for this thermal-diffusion based Fourier diffraction theorem to form the basis of tomographic reconstruction algorithms for quantitative thermal imaging

Computational adaptive optics for broadband optical interferometric tomography of biological tissue.

Science.gov (United States)

Adie, Steven G; Graf, Benedikt W; Ahmad, Adeel; Carney, P Scott; Boppart, Stephen A

2012-05-08

Aberrations in optical microscopy reduce image resolution and contrast, and can limit imaging depth when focusing into biological samples. Static correction of aberrations may be achieved through appropriate lens design, but this approach does not offer the flexibility of simultaneously correcting aberrations for all imaging depths, nor the adaptability to correct for sample-specific aberrations for high-quality tomographic optical imaging. Incorporation of adaptive optics (AO) methods have demonstrated considerable improvement in optical image contrast and resolution in noninterferometric microscopy techniques, as well as in optical coherence tomography. Here we present a method to correct aberrations in a tomogram rather than the beam of a broadband optical interferometry system. Based on Fourier optics principles, we correct aberrations of a virtual pupil using Zernike polynomials. When used in conjunction with the computed imaging method interferometric synthetic aperture microscopy, this computational AO enables object reconstruction (within the single scattering limit) with ideal focal-plane resolution at all depths. Tomographic reconstructions of tissue phantoms containing subresolution titanium-dioxide particles and of ex vivo rat lung tissue demonstrate aberration correction in datasets acquired with a highly astigmatic illumination beam. These results also demonstrate that imaging with an aberrated astigmatic beam provides the advantage of a more uniform depth-dependent signal compared to imaging with a standard gaussian beam. With further work, computational AO could enable the replacement of complicated and expensive optical hardware components with algorithms implemented on a standard desktop computer, making high-resolution 3D interferometric tomography accessible to a wider group of users and nonspecialists.

TH-C-17A-12: Integrated CBCT and Optical Tomography System On-Board a Small Animal Radiation Research Platform (SARRP)

Energy Technology Data Exchange (ETDEWEB)

Wang, K; Zhang, B; Eslami, S; Iordachita, I; Wong, J [Johns Hopkins University, Baltimore, MD (United States); Patterson, M [Hamilton Regional Cancer Ctr., Hamilton, ON (Canada)

2014-06-15

Purpose: We present a newly developed on-board optical tomography system for SARRP. Innovative features include the compact design and fast acquisition optical method to perform 3D soft tissue radiation guidance. Because of the on-board feature and the combination of the CBCT, diffusive optical tomography (DOT), bioluminescence and fluorescence tomography (BLT and FT), this integrated system is expected to provide more accurate soft tissue guidance than an off-line system as well as highly sensitive functional imaging in preclinical research. Methods: Images are acquired in the order of CBCT, DOT and then BLT/FT, where the SARRP CBCT and DOT are used to provide the anatomical and optical properties information to enhance the subsequent BLT/FT optical reconstruction. The SARRP stage is redesigned to include 9 imbedded optical fibers in contact with the animal's skin. These fibers, connected to a white light lamp or laser, serve as the light sources for the DOT or FT, respectively. A CCD camera with f/1.4 lens and multi-spectral filter set is used as the optical detector and is mounted on a portable cart ready to dock into the SARRP. No radiation is delivered during optical image acquisition. A 3-way mirror system capable of 180 degree rotation around the animal reflects the optical signal to the camera at multiple projection angles. A special black-painted dome covers the stage and provides the light shielding. Results: Spontaneous metastatic bioluminescent liver and lung tumor models will be used to validate the 3D BLT reconstruction. To demonstrate the capability of our FT system, GastroSense750 fluorescence agent will be used to imaging the mouse stomach and intestinal region in 3D. Conclusion: We expect that this integrated CBCT and optical tomography on-board a SARRP will present new research opportunities for pre-clinical radiation research. Supported by NCI RO1-CA 158100.

TH-C-17A-12: Integrated CBCT and Optical Tomography System On-Board a Small Animal Radiation Research Platform (SARRP)

International Nuclear Information System (INIS)

Wang, K; Zhang, B; Eslami, S; Iordachita, I; Wong, J; Patterson, M

2014-01-01

Purpose: We present a newly developed on-board optical tomography system for SARRP. Innovative features include the compact design and fast acquisition optical method to perform 3D soft tissue radiation guidance. Because of the on-board feature and the combination of the CBCT, diffusive optical tomography (DOT), bioluminescence and fluorescence tomography (BLT and FT), this integrated system is expected to provide more accurate soft tissue guidance than an off-line system as well as highly sensitive functional imaging in preclinical research. Methods: Images are acquired in the order of CBCT, DOT and then BLT/FT, where the SARRP CBCT and DOT are used to provide the anatomical and optical properties information to enhance the subsequent BLT/FT optical reconstruction. The SARRP stage is redesigned to include 9 imbedded optical fibers in contact with the animal's skin. These fibers, connected to a white light lamp or laser, serve as the light sources for the DOT or FT, respectively. A CCD camera with f/1.4 lens and multi-spectral filter set is used as the optical detector and is mounted on a portable cart ready to dock into the SARRP. No radiation is delivered during optical image acquisition. A 3-way mirror system capable of 180 degree rotation around the animal reflects the optical signal to the camera at multiple projection angles. A special black-painted dome covers the stage and provides the light shielding. Results: Spontaneous metastatic bioluminescent liver and lung tumor models will be used to validate the 3D BLT reconstruction. To demonstrate the capability of our FT system, GastroSense750 fluorescence agent will be used to imaging the mouse stomach and intestinal region in 3D. Conclusion: We expect that this integrated CBCT and optical tomography on-board a SARRP will present new research opportunities for pre-clinical radiation research. Supported by NCI RO1-CA 158100

Optical Coherence Tomography for Material Characterization

NARCIS (Netherlands)

Liu, P.

2014-01-01

Optical coherence tomography (OCT) is a non-invasive, contactless and high resolution imaging method, which allows the reconstruction of two or three dimensional depth-resolved images in turbid media. In the past 20 years, OCT has been extensively developed in the field of biomedical diagnostics,

Submicron Resolution Spectral-Domain Optical Coherence Tomography

KAUST Repository

Alarousu, Erkki; Jabbour, Ghassan

2013-01-01

Apparatuses and systems for submicron resolution spectral-domain optical coherence tomography (OCT) are disclosed. The system may use white light sources having wavelengths within 400-1000 nanometers, and achieve resolution below 1 .mu

Optical coherence tomography: Technique and applications

DEFF Research Database (Denmark)

Thomsen, Jakob Borup; Sander, Birgit; Mogensen, Mette

2009-01-01

Optical coherence tomography (OCT) is a noninvasive optical imaging modality providing real-time video rate images in two and three dimensions of biological tissues with micrometer resolution. OCT fills the gap between ultrasound and confocal microscopy, since it has a higher resolution than...... of retinal diseases. The potential of OCT in many other applications is currently being explored, such as in developmental biology, skin cancer diagnostics, vulnerable plaque detection in cardiology, esophageal diagnostics and a number of other applications within oncology....

Time reversal optical tomography locates fluorescent targets in a turbid medium

Science.gov (United States)

Wu, Binlin; Cai, W.; Gayen, S. K.

2013-03-01

A fluorescence optical tomography approach that extends time reversal optical tomography (TROT) to locate fluorescent targets embedded in a turbid medium is introduced. It uses a multi-source illumination and multi-detector signal acquisition scheme, along with TR matrix formalism, and multiple signal classification (MUSIC) to construct pseudo-image of the targets. The samples consisted of a single or two small tubes filled with water solution of Indocyanine Green (ICG) dye as targets embedded in a 250 mm × 250 mm × 60 mm rectangular cell filled with Intralipid-20% suspension as the scattering medium. The ICG concentration was 1μM, and the Intralipid-20% concentration was adjusted to provide ~ 1-mm transport length for both excitation wavelength of 790 nm and fluorescence wavelength around 825 nm. The data matrix was constructed using the diffusely transmitted fluorescence signals for all scan positions, and the TR matrix was constructed by multiplying data matrix with its transpose. A pseudo spectrum was calculated using the signal subspace of the TR matrix. Tomographic images were generated using the pseudo spectrum. The peaks in the pseudo images provided locations of the target(s) with sub-millimeter accuracy. Concurrent transmission TROT measurements corroborated fluorescence-TROT findings. The results demonstrate that TROT is a fast approach that can be used to obtain accurate three-dimensional position information of fluorescence targets embedded deep inside a highly scattering medium, such as, a contrast-enhanced tumor in a human breast.

Dynamic Optical Coherence Tomography in Dermatology

DEFF Research Database (Denmark)

Ulrich, Martina; Themstrup, Lotte; De Carvalho, Nathalie

2016-01-01

Optical coherence tomography (OCT) represents a non-invasive imaging technology, which may be applied to the diagnosis of non-melanoma skin cancer and which has recently been shown to improve the diagnostic accuracy of basal cell carcinoma. Technical developments of OCT continue to expand the app...

[Dome-shaped macula: appearance on ultrasound and optical coherence tomography].

Science.gov (United States)

Chéour, M; Ben Aleya, N; Brour, J; Falfoul, Y; Agrebi, S; Skhiri, M; Kraïem, A

2013-10-01

The purpose of our work is to demonstrate the role of optical coherence tomography and ocular ultrasound in the diagnosis of the dome-shaped macula in high myopia. We report the case of a patient with high myopia who presented with a decrease in visual acuity and metamorphopsia in the left eye. She underwent visual acuity measurement, biomicroscopic examination and measurement of axial length. B-mode ultrasound and optical coherence tomography showed a projection of the macula in the convexity of the myopic staphyloma confirming the diagnosis of dome-shaped macula. Dome-shaped macula is a recently discovered entity, which may be responsible for a decrease in visual acuity in patients with high myopic posterior staphyloma. Ultrasound and optical coherence tomography are very helpful in making the diagnosis. Copyright © 2013. Published by Elsevier Masson SAS.

Analysis of multiple scattering effects in optical Doppler tomography

DEFF Research Database (Denmark)

Yura, H.T.; Thrane, L.; Andersen, Peter E.

2005-01-01

Optical Doppler tomography (ODT) combines Doppler velocimetry and optical coherence tomography (OCT) to obtain high-resolution cross-sectional imaging of particle flow velocity in scattering media such as the human retina and skin. Here, we present the results of a theoretical analysis of ODT where...... multiple scattering effects are included. The purpose of this analysis is to determine how multiple scattering affects the estimation of the depth-resolved localized flow velocity. Depth-resolved velocity estimates are obtained directly from the corresponding mean or standard deviation of the observed...

IMAGING WITH MULTIMODAL ADAPTIVE-OPTICS OPTICAL COHERENCE TOMOGRAPHY IN MULTIPLE EVANESCENT WHITE DOT SYNDROME: THE STRUCTURE AND FUNCTIONAL RELATIONSHIP.

Science.gov (United States)

Labriola, Leanne T; Legarreta, Andrew D; Legarreta, John E; Nadler, Zach; Gallagher, Denise; Hammer, Daniel X; Ferguson, R Daniel; Iftimia, Nicusor; Wollstein, Gadi; Schuman, Joel S

2016-01-01

To elucidate the location of pathological changes in multiple evanescent white dot syndrome (MEWDS) with the use of multimodal adaptive optics (AO) imaging. A 5-year observational case study of a 24-year-old female with recurrent MEWDS. Full examination included history, Snellen chart visual acuity, pupil assessment, intraocular pressures, slit lamp evaluation, dilated fundoscopic exam, imaging with Fourier-domain optical coherence tomography (FD-OCT), blue-light fundus autofluorescence (FAF), fundus photography, fluorescein angiography, and adaptive-optics optical coherence tomography. Three distinct acute episodes of MEWDS occurred during the period of follow-up. Fourier-domain optical coherence tomography and adaptive-optics imaging showed disturbance in the photoreceptor outer segments (PR OS) in the posterior pole with each flare. The degree of disturbance at the photoreceptor level corresponded to size and extent of the visual field changes. All findings were transient with delineation of the photoreceptor recovery from the outer edges of the lesion inward. Hyperautofluorescence was seen during acute flares. Increase in choroidal thickness did occur with each active flare but resolved. Although changes in the choroid and RPE can be observed in MEWDS, Fourier-domain optical coherence tomography, and multimodal adaptive optics imaging localized the visually significant changes seen in this disease at the level of the photoreceptors. These transient retinal changes specifically occur at the level of the inner segment ellipsoid and OS/RPE line. En face optical coherence tomography imaging provides a detailed, yet noninvasive method for following the convalescence of MEWDS and provides insight into the structural and functional relationship of this transient inflammatory retinal disease.

Optical coherence tomography findings and retinal changes after vitrectomy for optic disc pit maculopathy

Directory of Open Access Journals (Sweden)

Gaurav Sanghi

2014-01-01

Full Text Available Purpose : To study the optical coherence tomography (OCT patterns in optic disc pit maculopathy and retinal changes after vitreous surgery. Materials and Methods : Retrospective review of consecutive cases with optic disc pit maculopathy seen at two tertiary eye institutes from January 2005 to June 2009. Results : Twenty-four eyes of 23 patients are included. The presenting visual acuity ranged from 20/400 to 20/20 (median:20/80. The median age at presentation was 24 years (range, 6-57 years. Optical coherence tomography demonstrated a combination of retinoschisis and outer layer detachment (OLD in 19 (79.17% eyes, OLD only in 3 (12.5% eyes and retinoschisis only in 2 (8.33% eyes. An obvious communication (outer layer hole between the schisis and OLD was seen in 14 (73.68% of the 19 eyes with both features. Of the 21 eyes with retinoschisis, schisis was present in multiple layers in 15 (71.43% and single layer in 6 (28.57% eyes. Eleven eyes underwent pars plana vitrectomy including creation of posterior vitreous detachment (PVD, fluid-air exchange, low intensity laser photocoagulation at the temporal edge of the optic disc pit and non-expansile perfluoropropane gas (14% injection. Five (45.45% of 11 eyes undergoing vitrectomy had complete resolution and 4 (36.36% eyes had partial resolution of maculopathy. Visual acuity improved in 8 (72.72% of 11 eyes. Conclusion : Optical coherence tomography demonstrates multiple layer schisis and outer layer detachment as main features of optic disc pit maculopathy. Vitrectomy with PVD induction, laser photocoagulation and gas tamponade results in anatomical and visual improvement in most cases with optic disc pit maculopathy.

Fundus autofluorescence and optical coherence tomography findings in thiamine responsive megaloblastic anemia.

Science.gov (United States)

Ach, Thomas; Kardorff, Rüdiger; Rohrschneider, Klaus

2015-01-01

To report ophthalmologic fundus autofluorescence and spectral domain optical coherence tomography findings in a patient with thiamine responsive megaloblastic anemia (TRMA). A 13-year-old girl with genetically proven TRMA was ophthalmologically (visual acuity, funduscopy, perimetry, electroretinogram) followed up over >5 years. Fundus imaging also included autofluorescence and spectral domain optical coherence tomography. During a 5-year follow-up, visual acuity and visual field decreased, despite a special TRMA diet. Funduscopy revealed bull's eye appearance, whereas fundus autofluorescence showed central and peripheral hyperfluorescence and perifoveal hypofluorescence. Spectral domain optical coherence tomography revealed affected inner segment ellipsoid band and irregularities in the retinal pigment epithelium and choroidea. Autofluorescence and spectral domain optical coherence tomography findings in a patient with TRMA show retinitis pigmentosa-like retina, retinal pigment epithelium, and choroid alterations. These findings might progress even under special TRMA diet, indispensable to life. Ophthalmologist should consider TRMA in patients with deafness and ophthalmologic disorders.

Thermo-elastic optical coherence tomography.

Science.gov (United States)

Wang, Tianshi; Pfeiffer, Tom; Wu, Min; Wieser, Wolfgang; Amenta, Gaetano; Draxinger, Wolfgang; van der Steen, Antonius F W; Huber, Robert; Soest, Gijs van

2017-09-01

The absorption of nanosecond laser pulses induces rapid thermo-elastic deformation in tissue. A sub-micrometer scale displacement occurs within a few microseconds after the pulse arrival. In this Letter, we investigate the laser-induced thermo-elastic deformation using a 1.5 MHz phase-sensitive optical coherence tomography (OCT) system. A displacement image can be reconstructed, which enables a new modality of phase-sensitive OCT, called thermo-elastic OCT. An analysis of the results shows that the optical absorption is a dominating factor for the displacement. Thermo-elastic OCT is capable of visualizing inclusions that do not appear on the structural OCT image, providing additional tissue type information.

Small-Animal Imaging Using Diffuse Fluorescence Tomography.

Science.gov (United States)

Davis, Scott C; Tichauer, Kenneth M

2016-01-01

Diffuse fluorescence tomography (DFT) has been developed to image the spatial distribution of fluorescence-tagged tracers in living tissue. This capability facilitates the recovery of any number of functional parameters, including enzymatic activity, receptor density, blood flow, and gene expression. However, deploying DFT effectively is complex and often requires years of know-how, especially for newer mutlimodal systems that combine DFT with conventional imaging systems. In this chapter, we step through the process of using MRI-DFT imaging of a receptor-targeted tracer in small animals.

Photoacoustic Tomography

Science.gov (United States)

Wang, Lihong V.

Photoacoustic tomography (PAT) refers to imaging that is based on the photoacoustic effect. Although the photoacoustic effect as a physical phenomenon was first reported on by Alexander Graham Bell in 1880 [1], PAT as an imaging technology was developed only after the advent of ultrasonic transducers, computers, and lasers [2-31]. A review on biomedical photoacoustics is available [32]. The motivation for PAT is to combine optical-absorption contrast with ultrasonic spatial resolution for deep imaging in the optical quasi-diffusive or diffusive regime. In PAT, the tissue is irradiated by usually a short-pulsed laser beam to achieve a thermal and acoustic impulse response (Fig. 19.1). Locally absorbed light is converted into heat, which is further converted to a pressure rise via thermo-elastic expansion. The initial pressure rise - determined by the local optical absorption coefficient (μ â ), fluence (ψ) and other thermal and mechanical properties - propagates as an ultrasonic wave, which is referred to as a photoacoustic wave.

Fundus autofluorescence and optical coherence tomography of congenital grouped albinotic spots.

Science.gov (United States)

Kim, David Y; Hwang, John C; Moore, Anthony T; Bird, Alan C; Tsang, Stephen H

2010-09-01

The purpose of this study was to describe the findings of fundus autofluores-cence (FAF) and optical coherence tomography in a series of patients with congenital grouped albinotic spots. Three eyes of three patients with congenital grouped albinotic spots were evaluated with FAF and optical coherence tomography imaging to evaluate the nature of the albinotic spots. In all three eyes with congenital grouped albinotic spots, FAF imaging showed autofluorescent spots corresponding to the albinotic spots seen on stereo biomicroscopy. One eye also had additional spots detected on FAF imaging that were not visible on stereo biomicroscopy or color fundus photographs. Fundus autofluorescence imaging of the spots showed decreased general autofluorescence and decreased peripheral autofluorescence surrounding central areas of retained or increased autofluorescence. Optical coherence tomography showed a disruption in signal from the hyperreflective layer corresponding to the inner and outer segment junction and increased signal backscattering from the choroid in the area of the spots. Fluorescein angiography showed early and stable hyperfluorescence of the spots without leakage. In this case series, FAF showed decreased autofluorescence of the spots consistent with focal retinal pigment epithelium atrophy or abnormal material blocking normal autofluorescence and areas of increased autofluorescence suggesting retinal pigment epithelium dysfunction. The findings of optical coherence tomography and fluorescein angiography suggest photoreceptor and retinal pigment epithelium layer abnormalities. Fundus autofluorescence and optical coherence tomography are useful noninvasive diagnostic adjuncts that can aid in the diagnosis of congenital grouped albinotic spots, help determine extent of disease, and contribute to our understanding of its pathophysiology.

Measurement of 3D refractive index distribution by optical diffraction tomography

Science.gov (United States)

Chi, Weining; Wang, Dayong; Wang, Yunxin; Zhao, Jie; Rong, Lu; Yuan, Yuanyuan

2018-01-01

Optical Diffraction Tomography (ODT), as a novel 3D imaging technique, can obtain a 3D refractive index (RI) distribution to reveal the important optical properties of transparent samples. According to the theory of ODT, an optical diffraction tomography setup is built based on the Mach-Zehnder interferometer. The propagation direction of object beam is controlled by a 2D translation stage, and 121 holograms based on different illumination angles are recorded by a Charge-coupled Device (CCD). In order to prove the validity and accuracy of the ODT, the 3D RI profile of microsphere with a known RI is firstly measured. An iterative constraint algorithm is employed to improve the imaging accuracy effectively. The 3D morphology and average RI of the microsphere are consistent with that of the actual situation, and the RI error is less than 0.0033. Then, an optical element fabricated by laser with a non-uniform RI is taken as the sample. Its 3D RI profile is obtained by the optical diffraction tomography system.

System for diffusing light from an optical fiber or light guide

Science.gov (United States)

Maitland, Duncan J [Pleasant Hill, CA; Wilson, Thomas S [San Leandro, CA; Benett, William J [Livermore, CA; Small, IV, Ward [

2008-06-10

A system for diffusing light from an optical fiber wherein the optical fiber is coupled to a light source, comprising forming a polymer element adapted to be connected to the optical fiber and incorporating a scattering element with the polymer element wherein the scattering element diffuses the light from the polymer element. The apparatus of the present invention comprises a polymer element operatively connected to the optical fiber and a scattering element operatively connected with the shape polymer element that diffuses the light from the polymer element.

Imaging actinic keratosis by high-definition optical coherence tomography. Histomorphologic correlation

DEFF Research Database (Denmark)

Boone, Marc A L M; Norrenberg, Sarah; Jemec, Gregor B E

2013-01-01

With the continued development of non-invasive therapies for actinic keratosis such as PDT and immune therapies, the non-invasive diagnosis and monitoring become increasingly relevant. High-definition optical coherence tomography is a high-resolution imaging tool, with micrometre resolution in both...... transversal and axial directions, enable to visualize individual cells up to a depth of around 570 μm filling the imaging gap between conventional optical coherence tomography and reflectance confocal microscopy. We sought to determine the feasibility of detecting and grading of actinic keratosis...... by this technique using criteria defined for reflectance confocal microscopy compared to histology. In this pilot study, skin lesions of 17 patients with a histologically proven actinic keratosis were imaged by high-definition optical coherence tomography just before excision and images analysed qualitatively...

Ceramic and polymeric dental onlays evaluated by photo-elasticity, optical coherence tomography, and micro-computed tomography

Science.gov (United States)

Sinescu, Cosmin; Negrutiu, Meda; Topala, Florin; Ionita, Ciprian; Negru, Radu; Fabriky, Mihai; Marcauteanu, Corina; Bradu, Adrian; Dobre, George; Marsavina, Liviu; Rominu, Mihai; Podoleanu, Adrian

2011-10-01

Dental onlays are restorations used to repair rear teeth that have a mild to moderate amount of decay. They can also be used to restore teeth that are cracked or fractured if the damage is not severe enough to require a dental crown. The use of onlays requires less tooth reduction than does the use of metal fillings. This allows dentists to conserve more of a patient's natural tooth structure in the treatment process. The aims of this study are to evaluate the biomechanical comportment of the dental onlays, by using the 3D photo elasticity method and to investigate the integrity of the structures and their fitting to the dental support. For this optical coherence tomography and micro-computed tomography were employed. Both methods were used to investigate 37 dental onlays, 17 integral polymeric and 20 integral ceramic. The results permit to observe materials defects inside the ceramic or polymeric onlays situate in the biomechanically tensioned areas that could lead to fracture of the prosthetic structure. Marginal fitting problems of the onlays related to the teeth preparations were presented in order to observe the possibility of secondary cavities. The resulted images from the optical coherence tomography were verified by the micro-computed tomography. In conclusion, the optical coherence tomography can be used as a clinical method in order to evaluate the integrity of the dental ceramic and polymeric onlays and to investigate the quality of the marginal fitting to the teeth preparations.

Spectral-domain optical coherence tomography on a silicon chip

NARCIS (Netherlands)

Akça, B.I.

2012-01-01

Optical coherence tomography (OCT) is a non-invasive optical technique for high-resolution cross-sectional imaging of specimens, with many applications in clinical medicine and industry (e.g. materials testing, quality assurance, and process control). Current state-of-the-art OCT systems operate in

Clinical optical coherence tomography combined with multiphoton tomography for evaluation of several skin disorders

Science.gov (United States)

König, Karsten; Speicher, Marco; Bückle, Rainer; Reckfort, Julia; McKenzie, Gordon; Welzel, Julia; Koehler, Martin J.; Elsner, Peter; Kaatz, Martin

2010-02-01

The first clinical trial of optical coherence tomography (OCT) combined with multiphoton tomography (MPT) and dermoscopy is reported. State-of-the-art (i) OCT systems for dermatology (e.g. multibeam swept source OCT), (ii) the femtosecond laser multiphoton tomograph DermaInspectTM, and (iii) digital dermoscopes were applied to 47 patients with a diversity of skin diseases and disorders such as skin cancer, psoriasis, hemangioma, connective tissue diseases, pigmented lesions, and autoimmune bullous skin diseases. Dermoscopy, also called 'epiluminescent microscopy', provides two-dimensional color images of the skin surface. OCT imaging is based on the detection of optical reflections within the tissue measured interferometrically whereas nonlinear excitation of endogenous fluorophores and the second harmonic generation are the bases of MPT images. OCT cross sectional "wide field" image provides a typical field of view of 5 x 2 mm2 and offers fast information on the depth and the volume of the investigated lesion. In comparison, multiphoton tomography presents 0.36 x 0.36 mm2 horizontal or diagonal sections of the region of interest within seconds with submicron resolution and down to a tissue depth of 200 μm. The combination of OCT and MPT provides a synergistic optical imaging modality for early detection of skin cancer and other skin diseases.

Posterior lattice degeneration characterized by spectral domain optical coherence tomography.

Science.gov (United States)

Manjunath, Varsha; Taha, Mohammed; Fujimoto, James G; Duker, Jay S

2011-03-01

The purpose of this study was to use high-resolution spectral domain optical coherence tomography in the characterization of retinal and vitreal morphological changes overlying posterior lattice degeneration. A cross-sectional retrospective analysis was performed on 13 eyes of 13 nonconsecutive subjects with posterior lattice degeneration seen at the New England Eye Center, Tufts Medical Center between October 2009 and January 2010. Spectral domain optical coherence tomography images taken through the region of lattice degeneration were qualitatively analyzed. Four characteristic changes of the retina and vitreous were seen in the 13 eyes with lattice degeneration: 1) anterior/posterior U-shaped vitreous traction; 2) retinal breaks; 3) focal retinal thinning; and 4) vitreous membrane formation. The morphologic appearance of vitreous traction and retinal breaks were found to be consistent with previous histologic reports. It is possible to image posterior lattice degeneration in many eyes using spectral domain optical coherence tomography and to visualize the spectrum of retinal and vitreous changes throughout the area of lattice degeneration.

Fiber-optic polarization diversity detection for rotary probe optical coherence tomography.

Science.gov (United States)

Lee, Anthony M D; Pahlevaninezhad, Hamid; Yang, Victor X D; Lam, Stephen; MacAulay, Calum; Lane, Pierre

2014-06-15

We report a polarization diversity detection scheme for optical coherence tomography with a new, custom, miniaturized fiber coupler with single mode (SM) fiber inputs and polarization maintaining (PM) fiber outputs. The SM fiber inputs obviate matching the optical lengths of the X and Y OCT polarization channels prior to interference and the PM fiber outputs ensure defined X and Y axes after interference. Advantages for this scheme include easier alignment, lower cost, and easier miniaturization compared to designs with free-space bulk optical components. We demonstrate the utility of the detection system to mitigate the effects of rapidly changing polarization states when imaging with rotating fiber optic probes in Intralipid suspension and during in vivo imaging of human airways.

Fiber optic-based optical coherence tomography (OCT) for dental applications

Science.gov (United States)

Everett, Matthew J.; Colston, Bill W., Jr.; Da Silva, Luiz B.; Otis, Linda L.

1998-09-01

We have developed a hand-held fiber optic based optical coherence tomography (OCT) system for scanning of the oral cavity. We have produced, using this scanning device, in vivo cross-sectional images of hard and soft dental tissues in human volunteers. Clinically relevant anatomical structures, including the gingival margin, periodontal sulcus, and dento- enamel junction, were visible in all the images. The cemento- enamel junction and the alveolar bone were identified in approximately two thirds of the images. These images represent, or our knowledge, the first in vivo OCT images of human dental tissue.

Fiber optic based optical coherence tomography (OCT) for dental applications

Energy Technology Data Exchange (ETDEWEB)

Everett, M. J., LLNL

1998-06-02

We have developed a hand-held fiber optic based optical coherence tomography (OCT) system for scanning of the oral cavity We have produced, using this scanning device, in viva cross-sectional images of hard and soft dental tissues in human volunteers Clinically relevant anatomical structures, including the gingival margin, periodontal sulcus, and dento-enamel junction, were visible in all the images The dento-enamel junction and the alveolar bone were identifiable in approximately two thirds of the images These images represent, to our knowledge, the first in viva OCT images of human dental tissue.

Evaluation of Laser-Assisted Trans-Nail Drug Delivery with Optical Coherence Tomography

Directory of Open Access Journals (Sweden)

Meng-Tsan Tsai

2016-12-01

Full Text Available The nail provides a functional protection to the fingertips and surrounding tissue from external injuries. The nail plate consists of three layers including dorsal, intermediate, and ventral layers. The dorsal layer consists of compact, hard keratins, limiting topical drug delivery through the nail. In this study, we investigate the application of fractional CO2 laser that produces arrays of microthermal ablation zones (MAZs to facilitate drug delivery in the nails. We utilized optical coherence tomography (OCT for real-time monitoring of the laser–skin tissue interaction, sparing the patient from an invasive surgical sampling procedure. The time-dependent OCT intensity variance was used to observe drug diffusion through an induced MAZ array. Subsequently, nails were treated with cream and liquid topical drugs to investigate the feasibility and diffusion efficacy of laser-assisted drug delivery. Our results show that fractional CO2 laser improves the effectiveness of topical drug delivery in the nail plate and that OCT could potentially be used for in vivo monitoring of the depth of laser penetration as well as real-time observations of drug delivery.

Dispersion free full range spectral intensity optical coherence tomography

DEFF Research Database (Denmark)

Jensen, Mikkel; Israelsen, Niels Møller; Maria, Michael

2017-01-01

Optical coherence tomography (OCT) is a non-invasive imaging technique with many applications and widespread use in ophthalmology [1]. The axial resolution in OCT is inversely proportional to the bandwidth of the optical source used, but the improved axial resolution comes at the price of more...

High-speed optical coherence tomography by circular interferometric ranging

Science.gov (United States)

Siddiqui, Meena; Nam, Ahhyun S.; Tozburun, Serhat; Lippok, Norman; Blatter, Cedric; Vakoc, Benjamin J.

2018-02-01

Existing three-dimensional optical imaging methods excel in controlled environments, but are difficult to deploy over large, irregular and dynamic fields. This means that they can be ill-suited for use in areas such as material inspection and medicine. To better address these applications, we developed methods in optical coherence tomography to efficiently interrogate sparse scattering fields, that is, those in which most locations (voxels) do not generate meaningful signal. Frequency comb sources are used to superimpose reflected signals from equispaced locations through optical subsampling. This results in circular ranging, and reduces the number of measurements required to interrogate large volumetric fields. As a result, signal acquisition barriers that have limited speed and field in optical coherence tomography are avoided. With a new ultrafast, time-stretched frequency comb laser design operating with 7.6 MHz to 18.9 MHz repetition rates, we achieved imaging of multi-cm3 fields at up to 7.5 volumes per second.

Flux density calibration in diffuse optical tomographic systems.

Science.gov (United States)

Biswas, Samir Kumar; Rajan, Kanhirodan; Vasu, Ram M

2013-02-01

The solution of the forward equation that models the transport of light through a highly scattering tissue material in diffuse optical tomography (DOT) using the finite element method gives flux density (Φ) at the nodal points of the mesh. The experimentally measured flux (Umeasured) on the boundary over a finite surface area in a DOT system has to be corrected to account for the system transfer functions (R) of various building blocks of the measurement system. We present two methods to compensate for the perturbations caused by R and estimate true flux density (Φ) from Umeasuredcal. In the first approach, the measurement data with a homogeneous phantom (Umeasuredhomo) is used to calibrate the measurement system. The second scheme estimates the homogeneous phantom measurement using only the measurement from a heterogeneous phantom, thereby eliminating the necessity of a homogeneous phantom. This is done by statistically averaging the data (Umeasuredhetero) and redistributing it to the corresponding detector positions. The experiments carried out on tissue mimicking phantom with single and multiple inhomogeneities, human hand, and a pork tissue phantom demonstrate the robustness of the approach.

Optical coherence tomography assessment and quantification of intracoronary thrombus: Status and perspectives

International Nuclear Information System (INIS)

Porto, Italo; Mattesini, Alessio; Valente, Serafina; Prati, Francesco; Crea, Filippo; Bolognese, Leonardo

2015-01-01

Coronary angiography is the “golden standard” imaging technique in interventional cardiology and it is still widely used to guide interventions. A major drawback of this technique, however, is that it is inaccurate in the evaluation and quantification of intracoronary thrombus burden, a critical prognosticator and predictor of intraprocedural complications in acute coronary syndromes. The introduction of optical coherence tomography (OCT) holds the promise of overcoming this important limitation, as near-infrared light is uniquely sensitive to hemoglobin, the pigment of red blood cells trapped in the thrombus. This narrative review will focus on the use of OCT for the assessment, evaluation and quantification of intracoronary thrombosis. - Highlights: • Thrombotic burden in acute coronary syndromes Is not adequately evaluated by standard coronary angiography, whereas Optical Coherence Tomography is exquisitely sensitive to the hemoglobin contained in red blood cells and can be used to precisely quantify thrombus. • Both research and clinical applications have been developed using the OCT-based evaluation of thrombus. In particular, whereas precise quantification scores are useful for comparing antithrombotic therapies in randomized trials, both pharmacological and mechanical, the most important practical applications for OCT-based assessment of thrombus are the individuation of culprit lesions in the context of diffuse atheromata in acute coronary syndromes, and the so-called “delayed stenting” strategies. • Improvements in 3D rendering techniques are on the verge of revolutionizing OCT-based thrombus assessment, allowing extremely precise quantification of the thrombotic burden

Optical coherence tomography assessment and quantification of intracoronary thrombus: Status and perspectives

Energy Technology Data Exchange (ETDEWEB)

Porto, Italo, E-mail: italo.porto@gmail.com [Interventional Cardiology Unit, San Donato Hospital, Arezzo (Italy); Mattesini, Alessio; Valente, Serafina [Interventional Cardiology Unit, Careggi Hospital, Florence (Italy); Prati, Francesco [Interventional Cardiology San Giovanni Hospital, Rome (Italy); CLI foundation (Italy); Crea, Filippo [Department of Cardiovascular Sciences, Catholic University of the Sacred Heart, Rome (Italy); Bolognese, Leonardo [Interventional Cardiology Unit, San Donato Hospital, Arezzo (Italy)

2015-04-15

Coronary angiography is the “golden standard” imaging technique in interventional cardiology and it is still widely used to guide interventions. A major drawback of this technique, however, is that it is inaccurate in the evaluation and quantification of intracoronary thrombus burden, a critical prognosticator and predictor of intraprocedural complications in acute coronary syndromes. The introduction of optical coherence tomography (OCT) holds the promise of overcoming this important limitation, as near-infrared light is uniquely sensitive to hemoglobin, the pigment of red blood cells trapped in the thrombus. This narrative review will focus on the use of OCT for the assessment, evaluation and quantification of intracoronary thrombosis. - Highlights: • Thrombotic burden in acute coronary syndromes Is not adequately evaluated by standard coronary angiography, whereas Optical Coherence Tomography is exquisitely sensitive to the hemoglobin contained in red blood cells and can be used to precisely quantify thrombus. • Both research and clinical applications have been developed using the OCT-based evaluation of thrombus. In particular, whereas precise quantification scores are useful for comparing antithrombotic therapies in randomized trials, both pharmacological and mechanical, the most important practical applications for OCT-based assessment of thrombus are the individuation of culprit lesions in the context of diffuse atheromata in acute coronary syndromes, and the so-called “delayed stenting” strategies. • Improvements in 3D rendering techniques are on the verge of revolutionizing OCT-based thrombus assessment, allowing extremely precise quantification of the thrombotic burden.

Optical coherence tomography as a diagnostic tool

CSIR Research Space (South Africa)

Singh, A

2011-07-01

Full Text Available Optical Coherence Tomography (OCT) has been used in biomedical applications as a method to non-invasively detect changes occurring in tissue such as the detection of skin cancer. The effect of skin tone on detection of skin cancer has however...

Computational adaptive optics for broadband interferometric tomography of tissues and cells

Science.gov (United States)

Adie, Steven G.; Mulligan, Jeffrey A.

2016-03-01

Adaptive optics (AO) can shape aberrated optical wavefronts to physically restore the constructive interference needed for high-resolution imaging. With access to the complex optical field, however, many functions of optical hardware can be achieved computationally, including focusing and the compensation of optical aberrations to restore the constructive interference required for diffraction-limited imaging performance. Holography, which employs interferometric detection of the complex optical field, was developed based on this connection between hardware and computational image formation, although this link has only recently been exploited for 3D tomographic imaging in scattering biological tissues. This talk will present the underlying imaging science behind computational image formation with optical coherence tomography (OCT) -- a beam-scanned version of broadband digital holography. Analogous to hardware AO (HAO), we demonstrate computational adaptive optics (CAO) and optimization of the computed pupil correction in 'sensorless mode' (Zernike polynomial corrections with feedback from image metrics) or with the use of 'guide-stars' in the sample. We discuss the concept of an 'isotomic volume' as the volumetric extension of the 'isoplanatic patch' introduced in astronomical AO. Recent CAO results and ongoing work is highlighted to point to the potential biomedical impact of computed broadband interferometric tomography. We also discuss the advantages and disadvantages of HAO vs. CAO for the effective shaping of optical wavefronts, and highlight opportunities for hybrid approaches that synergistically combine the unique advantages of hardware and computational methods for rapid volumetric tomography with cellular resolution.

Modeling of the blood flow in the lower extremities for dynamic diffuse optical tomography of peripheral artery disease

Science.gov (United States)

Marone, A.; Hoi, J. W.; Khalil, M. A.; Kim, H. K.; Shrikhande, G.; Dayal, R.; Hielscher, A. H.

2015-07-01

Peripheral Arterial Disease (PAD) is caused by a reduction of the internal diameters of the arteries in the upper or lower extremities mainly due to atherosclerosis. If not treated, its worsening may led to a complete occlusion, causing the death of the cells lacking proper blood supply, followed by gangrene that may require chirurgical amputation. We have recently performed a clinical study in which good sensitivities and specificities were achieved with dynamic diffuse optical tomography. To gain a better understanding of the physiological foundations of many of the observed effects, we started to develop a mathematical model for PAD. The model presented in this work is based on a multi-compartment Windkessel model, where the vasculature in the leg and foot is represented by resistors and capacitors, the blood pressure with a voltage drop, and the blood flow with a current. Unlike existing models, the dynamics induced by a thigh-pressure-cuff inflation and deflation during the measurements are taken into consideration. This is achieved by dynamically varying the resistances of the large veins and arteries. By including the effects of the thigh-pressure cuff, we were able to explain many of the effects observed during our dynamic DOT measurements, including the hemodynamics of oxy- and deoxy-hemoglobin concentration changes. The model was implemented in MATLAB and the simulations were normalized and compared with the blood perfusion obtained from healthy, PAD and diabetic patients. Our preliminary results show that in unhealthy patients the total system resistance is sensibly higher than in healthy patients.

Optical Doppler tomography based on a field programmable gate array

DEFF Research Database (Denmark)

Larsen, Henning Engelbrecht; Nilsson, Ronnie Thorup; Thrane, Lars

2008-01-01

We report the design of and results obtained by using a field programmable gate array (FPGA) to digitally process optical Doppler tomography signals. The processor fits into the analog signal path in an existing optical coherence tomography setup. We demonstrate both Doppler frequency and envelope...... extraction using the Hilbert transform, all in a single FPGA. An FPGA implementation has certain advantages over general purpose digital signal processor (DSP) due to the fact that the processing elements operate in parallel as opposed to the DSP. which is primarily a sequential processor....

Optical coherence tomography of the newborn airway.

Science.gov (United States)

Ridgway, James M; Su, Jianping; Wright, Ryan; Guo, Shuguang; Kim, David C; Barretto, Roberto; Ahuja, Gurpreet; Sepehr, Ali; Perez, Jorge; Sills, Jack H; Chen, Zhongping; Wong, Brian J F

2008-05-01

Acquired subglottic stenosis in a newborn is often associated with prolonged endotracheal intubation. This condition is generally diagnosed during operative endoscopy after airway injury has occurred. Unfortunately, endoscopy is unable to characterize the submucosal changes observed in such airway injuries. Other modalities, such as magnetic resonance imaging, computed tomography, and ultrasound, do not possess the necessary level of resolution to differentiate scar, neocartilage, and edema. Optical coherence tomography (OCT) is an imaging modality that produces high-resolution, cross-sectional images of living tissue (8 to 20 microm). We examined the ability of this noninvasive technique to characterize the newborn airway in a prospective clinical trial. Twelve newborn patients who required ventilatory support underwent OCT airway imaging. Comparative analysis of intubated and non-intubated states was performed. Imaging of the supraglottis, glottis, subglottis, and trachea was performed in 12 patients, revealing unique tissue characteristics as related to turbidity, signal backscattering, and architecture. Multiple structures were identified, including the vocal folds, cricoid cartilage, tracheal rings, ducts, glands, and vessels. Optical coherence tomography clearly identifies in vivo tissue layers and regional architecture while offering detailed information concerning tissue microstructures. The diagnostic potential of this technology makes OCT a promising modality in the study and surveillance of the neonatal airway.

On multi-spectral quantitative photoacoustic tomography in diffusive regime

International Nuclear Information System (INIS)

Bal, Guillaume; Ren, Kui

2012-01-01

The objective of quantitative photoacoustic tomography (qPAT) is to reconstruct the diffusion, absorption and Grüneisen thermodynamic coefficients of heterogeneous media from knowledge of the interior absorbed radiation. It has been shown in Bal and Ren (2011 Inverse Problems 27 075003), based on diffusion theory, that with data acquired at one given wavelength, all three coefficients cannot be reconstructed uniquely. In this work, we study the multi-spectral qPAT problem and show that when multiple wavelength data are available, all coefficients can be reconstructed simultaneously under minor prior assumptions. Moreover, the reconstructions are shown to be very stable. We present some numerical simulations that support the theoretical results. (paper)

Dual-wavelength photothermal optical coherence tomography for blood oxygen saturation measurement

Science.gov (United States)

Yin, Biwei; Kuranov, Roman V.; McElroy, Austin B.; Milner, Thomas E.

2013-03-01

We report design and demonstration of a dual wavelength photothermal (DWP) optical coherence tomography (OCT) system for imaging of a phantom microvessel and measurement of hemoglobin oxygen saturation (SO2) level. The DWP-OCT system contains a swept-source (SS) two-beam phase-sensitive (PhS) OCT system (1060 nm) and two intensity modulated photothermal excitation lasers (770 nm and 800 nm). The PhS-OCT probe beam (1060 nm) and photothermal excitation beams are combined into one single-mode optical fiber. A galvanometer based two-dimensional achromatic scanning system is designed to provide 14 μm lateral resolution for the PhS-OCT probe beam (1060 nm) and 13 μm lateral resolution for photothermal excitation beams. DWP-OCT system's sensitivity is 102 dB, axial resolution is 13 μm in tissue and uses a real-time digital dispersion compensation algorithm. Noise floor for optical pathlength measurements is 300 pm in the signal frequency range (380-400 Hz) of photothermal modulation frequencies. Blood SO2 level is calculated from measured optical pathlength (op) signal in a 300 μm diameter microvessel phantom introduced by the two photothermal excitation beams. En-face and B-scan images of a phantom microvessel are recorded, and six blood samples' SO2 levels are measured using DWP-OCT and compared with values provided by a commercial blood oximeter. A mathematical model indicates thermal diffusion introduces a systematic artifact that over-estimates SO2 values and is consistent with measured data.

Imaging of basal cell carcinoma by high-definition optical coherence tomography

DEFF Research Database (Denmark)

Boone, M A L M; Norrenberg, S; Jemec, G B E

2012-01-01

With the continued development of noninvasive therapies for basal cell carcinoma (BCC) such as photodynamic therapy and immune therapies, noninvasive diagnosis and monitoring become increasingly relevant. High-definition optical coherence tomography (HD-OCT) is a high-resolution imaging tool, wit......, with micrometre resolution in both transversal and axial directions, enabling visualization of individual cells up to a depth of around 570 μm, and filling the imaging gap between conventional optical coherence tomography (OCT) and reflectance confocal microscopy (RCM)....

Anomalous diffusion in a dynamical optical lattice

Science.gov (United States)

Zheng, Wei; Cooper, Nigel R.

2018-02-01

Motivated by experimental progress in strongly coupled atom-photon systems in optical cavities, we study theoretically the quantum dynamics of atoms coupled to a one-dimensional dynamical optical lattice. The dynamical lattice is chosen to have a period that is incommensurate with that of an underlying static lattice, leading to a dynamical version of the Aubry-André model which can cause localization of single-particle wave functions. We show that atomic wave packets in this dynamical lattice generically spread via anomalous diffusion, which can be tuned between superdiffusive and subdiffusive regimes. This anomalous diffusion arises from an interplay between Anderson localization and quantum fluctuations of the cavity field.

High-resolution retinal imaging using adaptive optics and Fourier-domain optical coherence tomography

Science.gov (United States)

Olivier, Scot S.; Werner, John S.; Zawadzki, Robert J.; Laut, Sophie P.; Jones, Steven M.

2010-09-07

This invention permits retinal images to be acquired at high speed and with unprecedented resolution in three dimensions (4.times.4.times.6 .mu.m). The instrument achieves high lateral resolution by using adaptive optics to correct optical aberrations of the human eye in real time. High axial resolution and high speed are made possible by the use of Fourier-domain optical coherence tomography. Using this system, we have demonstrated the ability to image microscopic blood vessels and the cone photoreceptor mosaic.

Reconstruction methods for sound visualization based on acousto-optic tomography

DEFF Research Database (Denmark)

Torras Rosell, Antoni; Lylloff, Oliver; Barrera Figueroa, Salvador

2013-01-01

The visualization of acoustic fields using acousto-optic tomography has recently proved to yield satisfactory results in the audible frequency range. The current implementation of this visualization technique uses a laser Doppler vibrometer (LDV) to measure the acousto-optic effect, that is, the ...

Miniature endoscopic optical coherence tomography for calculus detection.

Science.gov (United States)

Kao, Meng-Chun; Lin, Chun-Li; Kung, Che-Yen; Huang, Yi-Fung; Kuo, Wen-Chuan

2015-08-20

The effective treatment of periodontitis involves the detection and removal of subgingival dental calculus. However, subgingival calculus is more difficult to detect than supragingival calculus because it is firmly attached to root surfaces within periodontal pockets. To achieve a smooth root surface, clinicians often remove excessive amounts of root structure because of decreased visibility. In addition, enamel pearl, a rare type of ectopic enamel formation on the root surface, can easily be confused with dental calculus in the subgingival environment. In this study, we developed a fiber-probe swept-source optical coherence tomography (SSOCT) technique and combined it with the quantitative measurement of an optical parameter [standard deviation (SD) of the optical coherence tomography (OCT) intensity] to differentiate subgingival calculus from sound enamel, including enamel pearl. Two-dimensional circumferential images were constructed by rotating the miniprobe (0.9 mm diameter) while acquiring image lines, and the adjacent lines in each rotation were stacked to generate a three-dimensional volume. In OCT images, compared to sound enamel and enamel pearls, dental calculus showed significant differences (Pdental calculus.

Characterisation of optically cleared paper by optical coherence tomography

International Nuclear Information System (INIS)

Fabritius, T; Alarousu, E; Prykaeri, T; Hast, J; Myllylae, Risto

2006-01-01

Due to the highly light scattering nature of paper, the imaging depth of optical methods such as optical coherence tomography (OCT) is limited. In this work, we study the effect of refractive index matching on improving the imaging depth of OCT in paper. To this end, four different refractive index matching liquids (ethanol, 1-pentanol, glycerol and benzyl alcohol) with a refraction index between 1.359 and 1.538 were used in experiments. Low coherent light transmission was studied in commercial copy paper sheets, and the results indicate that benzyl alcohol offers the best improvement in imaging depth, while also being sufficiently stable for the intended purpose. Constructed cross-sectional images demonstrate visually that the imaging depth of OCT is considerably improved by optical clearing. Both surfaces of paper sheets can be detected along with information about the sheet's inner structure. (laser applications and other topics in quantum electronics)

The significance of computed tomography in optic neuropathy

International Nuclear Information System (INIS)

Awai, Tsugumi; Yasutake, Hirohide; Ono, Yoshiko; Kumagai, Kazuhisa; Kairada, Kensuke

1981-01-01

Computed tomography (CT scan) has become one of the important and useful modes of examination for ophthalmological and neuro-ophthalmological disorders. CT scan (EMI scan) was performed on 21 patients with optic neuropathy in order to detect the cause. Of these 21 patients, the CT scan was abnormal in six. These six patients were verified, histopathologically, as having chromophobe pituitary adenoma, craniopharyngioma, plasmocytoma from sphenoidal sinus, optic nerve glioma and giant aneurysma of anterior communicating artery. The practical diagnostic value of CT scan for optic neuropathy is discussed. (author)

Retinal pigment epithelium findings in patients with albinism using wide-field polarization-sensitive optical coherence tomography.

Science.gov (United States)

Schütze, Christopher; Ritter, Markus; Blum, Robert; Zotter, Stefan; Baumann, Bernhard; Pircher, Michael; Hitzenberger, Christoph K; Schmidt-Erfurth, Ursula

2014-11-01

To investigate pigmentation characteristics of the retinal pigment epithelium (RPE) in patients with albinism using wide-field polarization-sensitive optical coherence tomography compared with intensity-based spectral domain optical coherence tomography and fundus autofluorescence imaging. Five patients (10 eyes) with previously genetically diagnosed albinism and 5 healthy control subjects (10 eyes) were imaged by a wide-field polarization-sensitive optical coherence tomography system (scan angle: 40 × 40° on the retina), sensitive to melanin contained in the RPE, based on the polarization state of backscattered light. Conventional intensity-based spectral domain optical coherence tomography and fundus autofluorescence examinations were performed. Retinal pigment epithelium-pigmentation was analyzed qualitatively and quantitatively based on depolarization assessed by polarization-sensitive optical coherence tomography. This study revealed strong evidence of polarization-sensitive optical coherence tomography to specifically image melanin in the RPE. Depolarization of light backscattered by the RPE in patients with albinism was reduced compared with normal subjects. Heterogeneous RPE-specific depolarization characteristics were observed in patients with albinism. Reduction of depolarization observed in the light backscattered by the RPE in patients with albinism corresponds to expected decrease of RPE pigmentation. The degree of depigmentation of the RPE is possibly associated with visual acuity. Findings suggest that different albinism genotypes result in heterogeneous levels of RPE pigmentation. Polarization-sensitive optical coherence tomography showed a heterogeneous appearance of RPE pigmentation in patients with albinism depending on different genotypes.

Optical coherence tomography technology and applications

CERN Document Server

Fujimoto, James

2015-01-01

Optical coherence tomography (OCT) is the optical analog of ultrasound imaging and is a powerful imaging technique that enables non-invasive, in vivo, high resolution, cross-sectional imaging in biological tissue.  Between 30 to 40 Million OCT imaging procedures are performed per year in ophthalmology.  The overall market is estimated at more than 0.5 Billion USD.  A new generation OCT technology was developed, dramatically increasing resolution and speed, achieving in vivo optical biopsy, i.e. the visualization of tissue architectural morphology in situ and in real time.  Functional extensions of OCT technology enable non-invasive, depth resolved functional assessment and imaging of tissue.  The book introduces OCT technology and applications not only from an optical and technological viewpoint, but also from the biomedical and clinical perspective. This second edition is widely extended and covers significantly more topics then the first edition of this book. The chapters are written leading intern...

Benign familial fleck retina: multimodal imaging including optical coherence tomography angiography.

Science.gov (United States)

Garcia, Jose Mauricio Botto de Barros; Isaac, David Leonardo Cruvinel; Sardeiro, Tainara; Aquino, Érika; Avila, Marcos

2017-01-01

This report presents multimodal imaging of a 27-year-old woman diagnosed with benign familial fleck retina (OMIM 228980), an uncommon disorder. Fundus photographs revealed retinal flecks that affected her post-equatorial retina but spared the macular area. Fundus autofluorescence and infrared imaging demonstrated a symmetrical pattern of yellow-white fleck lesions that affected both eyes. Her full-field electroretinogram and electrooculogram were normal. An optical coherence tomography B-scan was performed for both eyes, revealing increased thickness of the retinal pigmented epithelium leading to multiple small pigmented epithelium detachments. The outer retina remained intact in both eyes. Spectral-domain optical coherence tomography angiography with split-spectrum amplitude decorrelation algorithm and 3 × 3 mm structural en face optical coherence tomography did not show macular lesions. Benign familial fleck retina belongs to a heterogenous group of so-called flecked retina syndromes, and should be considered in patients with yellowish-white retinal lesions without involvement of the macula.

Benign familial fleck retina: multimodal imaging including optical coherence tomography angiography

Directory of Open Access Journals (Sweden)

Jose Mauricio Botto de Barros Garcia

Full Text Available ABSTRACT This report presents multimodal imaging of a 27-year-old woman diagnosed with benign familial fleck retina (OMIM 228980, an uncommon disorder. Fundus photographs revealed retinal flecks that affected her post-equatorial retina but spared the macular area. Fundus autofluorescence and infrared imaging demonstrated a symmetrical pattern of yellow-white fleck lesions that affected both eyes. Her full-field electroretinogram and electrooculogram were normal. An optical coherence tomography B-scan was performed for both eyes, revealing increased thickness of the retinal pigmented epithelium leading to multiple small pigmented epithelium detachments. The outer retina remained intact in both eyes. Spectral-domain optical coherence tomography angiography with split-spectrum amplitude decorrelation algorithm and 3 × 3 mm structural en face optical coherence tomography did not show macular lesions. Benign familial fleck retina belongs to a heterogenous group of so-called flecked retina syndromes, and should be considered in patients with yellowish-white retinal lesions without involvement of the macula.

Optical theorem, depolarization and vector tomography

International Nuclear Information System (INIS)

Toperverg, B.P.

2003-01-01

A law of the total flux conservation is formulated in the form of the optical theorem. It is employed to explicitly derive equations for the description of the neutron polarization within the range of the direct beam defined by its angular divergence. General considerations are illustrated by calculations using the Born and Eikonal approximations. Results are briefly discussed as applied to Larmor-Fourier tomography

Diffuse optical tomography activation in the somatosensory cortex: specific activation by painful vs. non-painful thermal stimuli.

Directory of Open Access Journals (Sweden)

Lino Becerra

2009-11-01

Full Text Available Pain is difficult to assess due to the subjective nature of self-reporting. The lack of objective measures of pain has hampered the development of new treatments as well as the evaluation of current ones. Functional MRI studies of pain have begun to delineate potential brain response signatures that could be used as objective read-outs of pain. Using Diffuse Optical Tomography (DOT, we have shown in the past a distinct DOT signal over the somatosensory cortex to a noxious heat stimulus that could be distinguished from the signal elicited by innocuous mechanical stimuli. Here we further our findings by studying the response to thermal innocuous and noxious stimuli.Innocuous and noxious thermal stimuli were applied to the skin of the face of the first division (ophthalmic of the trigeminal nerve in healthy volunteers (N = 6. Stimuli temperatures were adjusted for each subject to evoke warm (equivalent to a 3/10 and painful hot (7/10 sensations in a verbal rating scale (0/10 = no/max pain. A set of 26 stimuli (5 sec each was applied for each temperature with inter-stimulus intervals varied between 8 and 15 sec using a Peltier thermode. A DOT system was used to capture cortical responses on both sides of the head over the primary somatosensory cortical region (S1. For the innocuous stimuli, group results indicated mainly activation on the contralateral side with a weak ipsilateral response. For the noxious stimuli, bilateral activation was observed with comparable amplitudes on both sides. Furthermore, noxious stimuli produced a temporal biphasic response while innocuous stimuli produced a monophasic response.These results are in accordance with fMRI and our other DOT studies of innocuous mechanical and noxious heat stimuli. The data indicate the differentiation of DOT cortical responses for pain vs. innocuous stimuli that may be useful in assessing objectively acute pain.

Depth-resolved imaging of colon tumor using optical coherence tomography and fluorescence laminar optical tomography (Conference Presentation)

Science.gov (United States)

Tang, Qinggong; Frank, Aaron; Wang, Jianting; Chen, Chao-wei; Jin, Lily; Lin, Jon; Chan, Joanne M.; Chen, Yu

2016-03-01

Early detection of neoplastic changes remains a critical challenge in clinical cancer diagnosis and treatment. Many cancers arise from epithelial layers such as those of the gastrointestinal (GI) tract. Current standard endoscopic technology is unable to detect those subsurface lesions. Since cancer development is associated with both morphological and molecular alterations, imaging technologies that can quantitative image tissue's morphological and molecular biomarkers and assess the depth extent of a lesion in real time, without the need for tissue excision, would be a major advance in GI cancer diagnostics and therapy. In this research, we investigated the feasibility of multi-modal optical imaging including high-resolution optical coherence tomography (OCT) and depth-resolved high-sensitivity fluorescence laminar optical tomography (FLOT) for structural and molecular imaging. APC (adenomatous polyposis coli) mice model were imaged using OCT and FLOT and the correlated histopathological diagnosis was obtained. Quantitative structural (the scattering coefficient) and molecular imaging parameters (fluorescence intensity) from OCT and FLOT images were developed for multi-parametric analysis. This multi-modal imaging method has demonstrated the feasibility for more accurate diagnosis with 87.4% (87.3%) for sensitivity (specificity) which gives the most optimal diagnosis (the largest area under receiver operating characteristic (ROC) curve). This project results in a new non-invasive multi-modal imaging platform for improved GI cancer detection, which is expected to have a major impact on detection, diagnosis, and characterization of GI cancers, as well as a wide range of epithelial cancers.

Quantitative photoacoustic microscopy of optical absorption coefficients from acoustic spectra in the optical diffusive regime.

Science.gov (United States)

Guo, Zijian; Favazza, Christopher; Garcia-Uribe, Alejandro; Wang, Lihong V

2012-06-01

Photoacoustic (PA) microscopy (PAM) can image optical absorption contrast with ultrasonic spatial resolution in the optical diffusive regime. Conventionally, accurate quantification in PAM requires knowledge of the optical fluence attenuation, acoustic pressure attenuation, and detection bandwidth. We circumvent this requirement by quantifying the optical absorption coefficients from the acoustic spectra of PA signals acquired at multiple optical wavelengths. With the acoustic spectral method, the absorption coefficients of an oxygenated bovine blood phantom at 560, 565, 570, and 575 nm were quantified with errors of <3%. We also quantified the total hemoglobin concentration and hemoglobin oxygen saturation in a live mouse. Compared with the conventional amplitude method, the acoustic spectral method provides greater quantification accuracy in the optical diffusive regime. The limitations of the acoustic spectral method was also discussed.

Optical coherence tomography of the rat cochlea

NARCIS (Netherlands)

Wong, B. J. F.; de Boer, JF; Park, B.H.; Chen, ZP; Nelson, JS

2000-01-01

Optical coherence tomography (OCT) was used to image the internal structure of a rat cochlea (ex vivo). Immediately following sacrifice, the temporal bone of a Sprague-Dawley rat was harvested. Axial OCT cross sectional images lover regions of interest, 1x1 mm-2x8 mm) were obtained with a spatial

Fundus Autofluorescence and Optical Coherence Tomography Findings in Branch Retinal Vein Occlusion

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Tetsuju Sekiryu

2012-01-01

Full Text Available Purpose. To describe the findings of fundus autofluorescence (FAF and optical coherence tomography (OCT in patients with branch retinal vein occlusion (BRVO. Methods. In this institutional, retrospective, observational case series, FAF was evaluated in 65 eyes with BRVO in 64 consecutive patients and compared with visual acuity, OCT findings, and other clinical observations. Results. Five types of autofluorescence appeared during the course of BRVO: (1 petaloid-shaped hyperautofluorescence in the area of macular edema and (2 hyperautofluorescence coincident with yellow subretinal deposits. (3 Diffuse hyperautofluorescence appeared within the area of serous retinal detachment (SRD and OCT showed precipitates on the undersurface of the retina in 5/5 of these eyes (100%. (4 The area of vein occlusion showed diffuse hyperautofluorescence after resolution of the retinal bleeding. (5 Hard exudates exhibited hyper- or hypoautofluorescence. OCT indicated that most of the hard exudates with hyperautofluorescence were located on the retinal pigment epithelium. Conclusions. Hyperautofluorescence associated with subretinal fluid or hard exudate appeared in the subretinal space. This type of hyperautofluorescence may be attributed to blood cell or macrophages. FAF and OCT are noninvasive modalities that provide additional information regarding macular edema due to BRVO.

Optical Coherence Tomography Technology and Quality Improvement Methods for Optical Coherence Tomography Images of Skin: A Short Review

Science.gov (United States)

Adabi, Saba; Turani, Zahra; Fatemizadeh, Emad; Clayton, Anne; Nasiriavanaki, Mohammadreza

2017-01-01

Optical coherence tomography (OCT) delivers 3-dimensional images of tissue microstructures. Although OCT imaging offers a promising high-resolution method, OCT images experience some artifacts that lead to misapprehension of tissue structures. Speckle, intensity decay, and blurring are 3 major artifacts in OCT images. Speckle is due to the low coherent light source used in the configuration of OCT. Intensity decay is a deterioration of light with respect to depth, and blurring is the consequence of deficiencies of optical components. In this short review, we summarize some of the image enhancement algorithms for OCT images which address the abovementioned artifacts. PMID:28638245

Optical Coherence Tomography Technology and Quality Improvement Methods for Optical Coherence Tomography Images of Skin: A Short Review

Directory of Open Access Journals (Sweden)

Saba Adabi

2017-06-01

Full Text Available Optical coherence tomography (OCT delivers 3-dimensional images of tissue microstructures. Although OCT imaging offers a promising high-resolution method, OCT images experience some artifacts that lead to misapprehension of tissue structures. Speckle, intensity decay, and blurring are 3 major artifacts in OCT images. Speckle is due to the low coherent light source used in the configuration of OCT. Intensity decay is a deterioration of light with respect to depth, and blurring is the consequence of deficiencies of optical components. In this short review, we summarize some of the image enhancement algorithms for OCT images which address the abovementioned artifacts.

Effects of acoustic radiation force and shear waves for absorption and stiffness sensing in ultrasound modulated optical tomography.

Science.gov (United States)

Li, Rui; Elson, Daniel S; Dunsby, Chris; Eckersley, Robert; Tang, Meng-Xing

2011-04-11

Ultrasound-modulated optical tomography (UOT) combines optical contrast with ultrasound spatial resolution and has great potential for soft tissue functional imaging. One current problem with this technique is the weak optical modulation signal, primarily due to strong optical scattering in diffuse media and minimal acoustically induced modulation. The acoustic radiation force (ARF) can create large particle displacements in tissue and has been shown to be able to improve optical modulation signals. However, shear wave propagation induced by the ARF can be a significant source of nonlocal optical modulation which may reduce UOT spatial resolution and contrast. In this paper, the time evolution of shear waves was examined on tissue mimicking-phantoms exposed to 5 MHz ultrasound and 532 nm optical radiation and measured with a CCD camera. It has been demonstrated that by generating an ARF with an acoustic burst and adjusting both the timing and the exposure time of the CCD measurement, optical contrast and spatial resolution can be improved by ~110% and ~40% respectively when using the ARF rather than 5 MHz ultrasound alone. Furthermore, it has been demonstrated that this technique simultaneously detects both optical and mechanical contrast in the medium and the optical and mechanical contrast can be distinguished by adjusting the CCD exposure time. © 2011 Optical Society of America

Performance dependence of hybrid x-ray computed tomography/fluorescence molecular tomography on the optical forward problem.

Science.gov (United States)

Hyde, Damon; Schulz, Ralf; Brooks, Dana; Miller, Eric; Ntziachristos, Vasilis

2009-04-01

Hybrid imaging systems combining x-ray computed tomography (CT) and fluorescence tomography can improve fluorescence imaging performance by incorporating anatomical x-ray CT information into the optical inversion problem. While the use of image priors has been investigated in the past, little is known about the optimal use of forward photon propagation models in hybrid optical systems. In this paper, we explore the impact on reconstruction accuracy of the use of propagation models of varying complexity, specifically in the context of these hybrid imaging systems where significant structural information is known a priori. Our results demonstrate that the use of generically known parameters provides near optimal performance, even when parameter mismatch remains.

Time reversal optical tomography and decomposition methods for detection and localization of targets in highly scattering turbid media

Science.gov (United States)

Wu, Binlin

New near-infrared (NIR) diffuse optical tomography (DOT) approaches were developed to detect, locate, and image small targets embedded in highly scattering turbid media. The first approach, referred to as time reversal optical tomography (TROT), is based on time reversal (TR) imaging and multiple signal classification (MUSIC). The second approach uses decomposition methods of non-negative matrix factorization (NMF) and principal component analysis (PCA) commonly used in blind source separation (BSS) problems, and compare the outcomes with that of optical imaging using independent component analysis (OPTICA). The goal is to develop a safe, affordable, noninvasive imaging modality for detection and characterization of breast tumors in early growth stages when those are more amenable to treatment. The efficacy of the approaches was tested using simulated data, and experiments involving model media and absorptive, scattering, and fluorescent targets, as well as, "realistic human breast model" composed of ex vivo breast tissues with embedded tumors. The experimental arrangements realized continuous wave (CW) multi-source probing of samples and multi-detector acquisition of diffusely transmitted signal in rectangular slab geometry. A data matrix was generated using the perturbation in the transmitted light intensity distribution due to the presence of absorptive or scattering targets. For fluorescent targets the data matrix was generated using the diffusely transmitted fluorescence signal distribution from the targets. The data matrix was analyzed using different approaches to detect and characterize the targets. The salient features of the approaches include ability to: (a) detect small targets; (b) provide three-dimensional location of the targets with high accuracy (~within a millimeter or 2); and (c) assess optical strength of the targets. The approaches are less computation intensive and consequently are faster than other inverse image reconstruction methods that

Classifying murine glomerulonephritis using optical coherence tomography and optical coherence elastography.

Science.gov (United States)

Liu, Chih-Hao; Du, Yong; Singh, Manmohan; Wu, Chen; Han, Zhaolong; Li, Jiasong; Chang, Anthony; Mohan, Chandra; Larin, Kirill V

2016-08-01

Acute glomerulonephritis caused by antiglomerular basement membrane marked by high mortality. The primary reason for this is delayed diagnosis via blood examination, urine analysis, tissue biopsy, or ultrasound and X-ray computed tomography imaging. Blood, urine, and tissue-based diagnoses can be time consuming, while ultrasound and CT imaging have relatively low spatial resolution, with reduced sensitivity. Optical coherence tomography is a noninvasive and high-resolution imaging technique that provides superior spatial resolution (micrometer scale) as compared to ultrasound and CT. Changes in tissue properties can be detected based on the optical metrics analyzed from the OCT signals, such as optical attenuation and speckle variance. Furthermore, OCT does not rely on ionizing radiation as with CT imaging. In addition to structural changes, the elasticity of the kidney can significantly change due to nephritis. In this work, OCT has been utilized to quantify the difference in tissue properties between healthy and nephritic murine kidneys. Although OCT imaging could identify the diseased tissue, its classification accuracy is clinically inadequate. By combining optical metrics with elasticity, the classification accuracy improves from 76% to 95%. These results show that OCT combined with OCE can be a powerful tool for identifying and classifying nephritis. Therefore, the OCT/OCE method could potentially be used as a minimally invasive tool for longitudinal studies during the progression and therapy of glomerulonephritis as well as complement and, perhaps, substitute highly invasive tissue biopsies. Elastic-wave propagation in mouse healthy and nephritic kidneys. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Online monitoring of printed electronics by Spectral-Domain Optical Coherence Tomography

KAUST Repository

Alarousu, Erkki; Alsaggaf, Ahmed; Jabbour, Ghassan E.

2013-01-01

Spectral-Domain Optical Coherence Tomography (SD-OCT) is an optical method capable of 3D imaging of object's internal structure with micron-scale resolution. Modern SD-OCT tools offer the speed capable of online monitoring of printed devices

Optical coherence tomography angiography changes in radial peripapillary capillaries in Leber hereditary optic neuropathy

Directory of Open Access Journals (Sweden)

Mitsuhiro Matsuzaki

2018-03-01

Conclusions and importance: Optical coherence tomography angiography showed LHON from the presymptomatic stage. The results indicate that temporal RPC defects and RFT thinning start to spread once the pseudoedema begins to resolve.

3-D anisotropic neutron diffusion in optically thick media with optically thin channels

International Nuclear Information System (INIS)

Trahan, Travis J.; Larsen, Edward W.

2011-01-01

Standard neutron diffusion theory accurately approximates the neutron transport process for optically thick, scattering-dominated systems in which the angular neutron flux is a weak (nearly linear) function of angle. Therefore, standard diffusion theory is not directly applicable for Very High Temperature Reactor (VHTR) cores, which contain numerous narrow, axially-oriented, nearly-voided coolant channels. However, we have derived a new, accurate diffusion equation for such problems, which contains nonstandard anisotropic diffusion coefficients near and within the channels, but which reduces to the standard diffusion approximation away from the channels. The new diffusion approximation significantly improves the accuracy of VHTR diffusion simulations, while having lower computational cost than higher-order transport methods. (author)

Spectral-domain optical coherence tomography findings of the macula in 500 consecutive patients with uveitis.

Science.gov (United States)

Grajewski, R S; Boelke, A C; Adler, W; Meyer, S; Caramoy, A; Kirchhof, B; Cursiefen, C; Heindl, L M

2016-11-01

PurposeTo analyze the macular structure in a large series of consecutive patients with different types of uveitis using spectral-domain optical coherence tomography (SD-OCT).Patients and methodsFive hundred eyes of 500 consecutive patients with anterior, intermediate, posterior, and panuveitis underwent standardized macular examination using SD-OCT. Central retinal thickness (CRT), macular volume (MV), and presence of cystoid macular edema (CME), diffuse macular edema (DME), serous retinal detachment (SRD), epiretinal membrane with (ERM+) and without (ERM-) retinal surface wrinkling were determined.ResultsThe anatomic location of inflammation affected significantly CRT and MV (Pmacula is recommended for all uveitis patients. CRT, MV, and the incidence of CME were highest in intermediate and panuveitis.

The Linearity of Optical Tomography: Sensor Model and Experimental Verification

Directory of Open Access Journals (Sweden)

Siti Zarina MOHD. MUJI

2011-09-01

Full Text Available The aim of this paper is to show the linearization of optical sensor. Linearity of the sensor response is a must in optical tomography application, which affects the tomogram result. Two types of testing are used namely, testing using voltage parameter and testing with time unit parameter. For the former, the testing is by measuring the voltage when the obstacle is placed between transmitter and receiver. The obstacle diameters are between 0.5 until 3 mm. The latter is also the same testing but the obstacle is bigger than the former which is 59.24 mm and the testing purpose is to measure the time unit spend for the ball when it cut the area of sensing circuit. Both results show a linear relation that proves the optical sensors is suitable for process tomography application.

Modeling bioluminescent photon transport in tissue based on Radiosity-diffusion model

Science.gov (United States)

Sun, Li; Wang, Pu; Tian, Jie; Zhang, Bo; Han, Dong; Yang, Xin

2010-03-01

Bioluminescence tomography (BLT) is one of the most important non-invasive optical molecular imaging modalities. The model for the bioluminescent photon propagation plays a significant role in the bioluminescence tomography study. Due to the high computational efficiency, diffusion approximation (DA) is generally applied in the bioluminescence tomography. But the diffusion equation is valid only in highly scattering and weakly absorbing regions and fails in non-scattering or low-scattering tissues, such as a cyst in the breast, the cerebrospinal fluid (CSF) layer of the brain and synovial fluid layer in the joints. A hybrid Radiosity-diffusion model is proposed for dealing with the non-scattering regions within diffusing domains in this paper. This hybrid method incorporates a priori information of the geometry of non-scattering regions, which can be acquired by magnetic resonance imaging (MRI) or x-ray computed tomography (CT). Then the model is implemented using a finite element method (FEM) to ensure the high computational efficiency. Finally, we demonstrate that the method is comparable with Mont Carlo (MC) method which is regarded as a 'gold standard' for photon transportation simulation.

Optical coherence tomography of dental structures

Science.gov (United States)

Baumgartner, Angela; Hitzenberger, Christoph K.; Dichtl, Sabine; Sattmann, Harald; Moritz, Andreas; Sperr, Wolfgang; Fercher, Adolf F.

1998-04-01

In the past ten years Partial Coherence Interferometry (PCI) and Optical Coherence Tomography (OCT) have been successfully developed for high precision biometry and tomography of biological tissues. OCT employs the partial coherence properties of a superluminescent diode and the Doppler principle yielding resolution and precision figures of the order of a few microns. Presently, the main application fields of this technique are biometry and imaging of ocular structures in vivo, as well as its clinical use in dermatology and endoscopic applications. This well established length measuring and imaging technique has now been applied to dentistry. First in vitro OCT images of the cemento (dentine) enamel junction of extracted sound and decayed human teeth have been recorded. These images distinguish dentine and enamel structures that are important for assessing enamel thickness and diagnosing caries. Individual optical A-Scans show that the penetration depth into enamel is considerably larger than into dentine. First polarization sensitive OCT recordings show localized changes of the polarization state of the light backscattered by dental material. Two-dimensional maps of the magnitude of the interference intensity and of the total phase difference between two orthogonal polarization states as a function of depth can reveal important structural information.

Fluorine-18-fluorodeoxyglucose Positron Emission Tomography in Diffuse Large B-cell Lymphoma

DEFF Research Database (Denmark)

Mylam, Karen Juul; Nielsen, Anne Lerberg; Pedersen, Lars Møller

2014-01-01

Diffuse large B-cell lymphoma (DLBCL) is an aggressive and potentially curable type of lymphoma. Fluorine-18-fluorodeoxyglucose positron emission tomography (FDG-PET) is part of clinical routine for DLBCL in most hospitals and also recommended for staging and end-of-therapy evaluation. FDG......-PET/computed tomography (CT) is able to identify nodal and extranodal sites with greater accuracy than CT alone. Little evidence supports the use of surveillance FDG-PET imaging in the follow-up setting because of high rates of false-positive scans and because most studies are retrospective. This article discusses FDG...

Numerical analysis of modal tomography for solar multi-conjugate adaptive optics

International Nuclear Information System (INIS)

Dong Bing; Ren Deqing; Zhang Xi

2012-01-01

Multi-conjugate adaptive optics (MCAO) can considerably extend the corrected field of view with respect to classical adaptive optics, which will benefit solar observation in many aspects. In solar MCAO, the Sun structure is utilized to provide multiple guide stars and a modal tomography approach is adopted to implement three-dimensional wavefront restorations. The principle of modal tomography is briefly reviewed and a numerical simulation model is built with three equivalent turbulent layers and a different number of guide stars. Our simulation results show that at least six guide stars are required for an accurate wavefront reconstruction in the case of three layers, and only three guide stars are needed in the two layer case. Finally, eigenmode analysis results are given to reveal the singular modes that cannot be precisely retrieved in the tomography process.

Stable dissipative optical vortex clusters by inhomogeneous effective diffusion.

Science.gov (United States)

Li, Huishan; Lai, Shiquan; Qui, Yunli; Zhu, Xing; Xie, Jianing; Mihalache, Dumitru; He, Yingji

2017-10-30

We numerically show the generation of robust vortex clusters embedded in a two-dimensional beam propagating in a dissipative medium described by the generic cubic-quintic complex Ginzburg-Landau equation with an inhomogeneous effective diffusion term, which is asymmetrical in the two transverse directions and periodically modulated in the longitudinal direction. We show the generation of stable optical vortex clusters for different values of the winding number (topological charge) of the input optical beam. We have found that the number of individual vortex solitons that form the robust vortex cluster is equal to the winding number of the input beam. We have obtained the relationships between the amplitudes and oscillation periods of the inhomogeneous effective diffusion and the cubic gain and diffusion (viscosity) parameters, which depict the regions of existence and stability of vortex clusters. The obtained results offer a method to form robust vortex clusters embedded in two-dimensional optical beams, and we envisage potential applications in the area of structured light.

Fast Industrial Inspection of Optical Thin Film Using Optical Coherence Tomography

Directory of Open Access Journals (Sweden)

Muhammad Faizan Shirazi

2016-09-01

Full Text Available An application of spectral domain optical coherence tomography (SD-OCT was demonstrated for a fast industrial inspection of an optical thin film panel. An optical thin film sample similar to a liquid crystal display (LCD panel was examined. Two identical SD-OCT systems were utilized for parallel scanning of a complete sample in half time. Dual OCT inspection heads were utilized for transverse (fast scanning, while a stable linear motorized translational stage was used for lateral (slow scanning. The cross-sectional and volumetric images of an optical thin film sample were acquired to detect the defects in glass and other layers that are difficult to observe using visual inspection methods. The rapid inspection enabled by this setup led to the early detection of product defects on the manufacturing line, resulting in a significant improvement in the quality assurance of industrial products.

Engineering of Nanoscale Contrast Agents for Optical Coherence Tomography.

Science.gov (United States)

Gordon, Andrew Y; Jayagopal, Ashwath

2014-01-30

Optical coherence tomography has emerged as valuable imaging modalityin ophthalmology and other fields by enabling high-resolution three-dimensional imaging of tissue. In this paper, we review recent progress in the field of contrast-enhanced optical coherence tomography (OCT). We discuss exogenous and endogenous sources of OCT contrast, focusing on their use with standard OCT systems as well as emerging OCT-based imaging modalities. We include advances in the processing of OCT data that generate improved tissue contrast, including spectroscopic OCT (SOCT), as well as work utilizing secondary light sources and/or detection mechanisms to create and detect enhanced contrast, including photothermal OCT (PTOCT) and photoacoustic OCT (PAOCT). Finally, we conclude with a discussion of the translational potential of these developments as well as barriers to their clinical use.

Full Spectrum Diffused and Beamed Solar Energy Application Using Optical Fibre

OpenAIRE

Majumdar, M. R. Dutta; Das, Debasish

2007-01-01

Existing solar energy application systems use small fraction of full spectrum of solar energy. So attempts are made to show how full spectrum solar energy can be used for diffused and beamed form of incident solar energy. Luminescent Solar Concentrator (LSC) principle with optical fibre in diffused sun light and dielectric mirror separation technique with optical fibre in beamed form are discussed. Comparison of both the cases are done. Keywords: full spectrum, solar photonics, diffused solar...

Spectral-domain optical coherence tomography of roth spots.

Science.gov (United States)

Giovinazzo, Jerome; Mrejen, Sarah; Freund, K Bailey

2013-01-01

To describe the retinal findings of subacute bacterial endocarditis, their evolution after treatment, and analysis with spectral-domain optical coherence tomography. Retrospective chart review. A 21-year-old man presented with the sudden onset of a central scotoma in his left eye because of a sub-internal limiting membrane hemorrhage overlying the left fovea. When examined 2 weeks later, Roth spots were noted in his right eye. The patient was immediately referred to his internist and diagnosed with subacute bacterial endocarditis with cultures positive for Streptococcus viridans. He subsequently underwent aortic valve replacement surgery after 4 weeks of intravenous antibiotic therapy. When examined 4 weeks after valve replacement surgery, there was regression of the Roth spots. The present case demonstrates the importance of a funduscopic examination in the early diagnosis and management of subacute bacterial endocarditis. The analysis of Roth spots with spectral-domain optical coherence tomography suggested that they were septic emboli.

Optical coherence tomography and subclinical optical neuritis in longitudinally extensive transverse myelitis

Directory of Open Access Journals (Sweden)

Prakash Kumar Sinha

2017-01-01

Full Text Available Objective: The aim is to compare the retinal nerve fiber layer (RNFL thickness of longitudinally extensive transverse myelitis (LETM eyes without previous optic neuritis with that of healthy control subjects. Methods: Over 20 LETM eyes and 20 normal control eyes were included in the study and subjected to optical coherence tomography to evaluate and compare the RNFL thickness. Result: Significant RNFL thinning was observed at 8 o'clock position in LETM eyes as compared to the control eyes (P = 0.038. No significant differences were seen in other RNFL measurements. Conclusion: Even in the absence of previous optic neuritis LETM can lead to subclinical axonal damage leading to focal RNFL thinning.

Block matching 3D random noise filtering for absorption optical projection tomography

International Nuclear Information System (INIS)

Fumene Feruglio, P; Vinegoni, C; Weissleder, R; Gros, J; Sbarbati, A

2010-01-01

Absorption and emission optical projection tomography (OPT), alternatively referred to as optical computed tomography (optical-CT) and optical-emission computed tomography (optical-ECT), are recently developed three-dimensional imaging techniques with value for developmental biology and ex vivo gene expression studies. The techniques' principles are similar to the ones used for x-ray computed tomography and are based on the approximation of negligible light scattering in optically cleared samples. The optical clearing is achieved by a chemical procedure which aims at substituting the cellular fluids within the sample with a cell membranes' index matching solution. Once cleared the sample presents very low scattering and is then illuminated with a light collimated beam whose intensity is captured in transillumination mode by a CCD camera. Different projection images of the sample are subsequently obtained over a 360 0 full rotation, and a standard backprojection algorithm can be used in a similar fashion as for x-ray tomography in order to obtain absorption maps. Because not all biological samples present significant absorption contrast, it is not always possible to obtain projections with a good signal-to-noise ratio, a condition necessary to achieve high-quality tomographic reconstructions. Such is the case for example, for early stage's embryos. In this work we demonstrate how, through the use of a random noise removal algorithm, the image quality of the reconstructions can be considerably improved even when the noise is strongly present in the acquired projections. Specifically, we implemented a block matching 3D (BM3D) filter applying it separately on each acquired transillumination projection before performing a complete three-dimensional tomographical reconstruction. To test the efficiency of the adopted filtering scheme, a phantom and a real biological sample were processed. In both cases, the BM3D filter led to a signal-to-noise ratio increment of over 30 d

Experimental investigation of the diffusion coefficients in porous media by application of X-ray computer tomography

DEFF Research Database (Denmark)

Zhelezny, Petr; Shapiro, Alexander

2006-01-01

The present work describes a new experimental method that makes it possible to investigate diffusion coefficients in a porous medium. The method is based on application of X-ray computed tomography (CT). The general applicability of this method for the determination of diffusion coefficients...

Diffusion-weighted imaging helps differentiate multiple sclerosis and neuromyelitis optica-related acute optic neuritis.

Science.gov (United States)

Wan, Hailin; He, Huijin; Zhang, Fang; Sha, Yan; Tian, Guohong

2017-06-01

To evaluate the apparent diffusion coefficient (ADC) values between multiple sclerosis (MS) and neuromyelitis optica (NMO)-related acute optic neuritis (ON) patients and predict their optic nerve atrophy of optic coherence tomography (OCT) parameters. Nineteen MS and 15 NMO-related acute ON patients who underwent a diffusion-weighted imaging sequence in 3.0 Tesla MR scanner and a follow-up OCT examination after 6 months were included. The ADC values, thickness of the retinal nerve fiber layer (RNFL) and the macular ganglion cell complex (GCC) between MS and NMO related ON were assessed. The mean ADC value of the NMO-ON, (0.691 ± 0.195[SD]) × 10 -3 mm 2 /s, was significantly smaller (P = 0.0133) than that of MS-ON. The mean ADC value of MS-ON, (0.879 ± 0.144) × 10 -3 mm 2 /s, was significantly smaller (P < 0.0001) than that of control group, (1.025 ± 0.067) × 10 -3 mm 2 /s. Using an ADC value smaller than 0.830 × 10 -3 mm 2 /s as the threshold value for differentiating MS-ON from NMO-ON patients, the highest accuracy of 76.7%, with 75.0% sensitivity and 78.3% specificity, was obtained. The ADC value measured at the acute stage of ON was correlated with the thickness of the RNFL (r = 0.441; P = 0.006) and the GCC (r = 0.526; P < 0.0001) after 6 months. The ADC value might be helpful for differentiating MS-ON from NMO-ON patients. The decreased ADC value was correlated with optic nerve atrophy on OCT. 3 Technical Efficacy: Stage 2 J. MAGN. RESON. IMAGING 2017;45:1780-1785. © 2016 International Society for Magnetic Resonance in Medicine.

CAPILLARY NETWORK ANOMALIES IN BRANCH RETINAL VEIN OCCLUSION ON OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY.

Science.gov (United States)

Rispoli, Marco; Savastano, Maria Cristina; Lumbroso, Bruno

2015-11-01

To analyze the foveal microvasculature features in eyes with branch retinal vein occlusion (BRVO) using optical coherence tomography angiography based on split spectrum amplitude decorrelation angiography technology. A total of 10 BRVO eyes (mean age 64.2 ± 8.02 range between 52 years and 76 years) were evaluated by optical coherence tomography angiography (XR-Avanti; Optovue). The macular angiography scan protocol covered a 3 mm × 3 mm area. The focus of angiography analysis were two retinal layers: superficial vascular network and deep vascular network. The following vascular morphological congestion parameters were assessed in the vein occlusion area in both the superficial and deep networks: foveal avascular zone enlargement, capillary non-perfusion occurrence, microvascular abnormalities appearance, and vascular congestion signs. Image analyses were performed by 2 masked observers and interobserver agreement of image analyses was 0.90 (κ = 0.225, P network of BRVO, a decrease in capillary density with foveal avascular zone enlargement, capillary non-perfusion occurrence, and microvascular abnormalities appearance was observed (P network showed the main vascular congestion at the boundary between healthy and nonperfused retina. Optical coherence tomography angiography in BRVO allows to detect foveal avascular zone enlargement, capillary nonperfusion, microvascular abnormalities, and vascular congestion signs both in the superficial and deep capillary network in all eyes. Optical coherence tomography angiography technology is a potential clinical tool for BRVO diagnosis and follow-up, providing stratigraphic vascular details that have not been previously observed by standard fluorescein angiography. The normal retinal vascular nets and areas of nonperfusion and congestion can be identified at various retinal levels. Optical coherence tomography angiography provides noninvasive images of the retinal capillaries and vascular networks.

Extended depth of focus adaptive optics spectral domain optical coherence tomography

Science.gov (United States)

Sasaki, Kazuhiro; Kurokawa, Kazuhiro; Makita, Shuichi; Yasuno, Yoshiaki

2012-01-01

We present an adaptive optics spectral domain optical coherence tomography (AO-SDOCT) with a long focal range by active phase modulation of the pupil. A long focal range is achieved by introducing AO-controlled third-order spherical aberration (SA). The property of SA and its effects on focal range are investigated in detail using the Huygens-Fresnel principle, beam profile measurement and OCT imaging of a phantom. The results indicate that the focal range is extended by applying SA, and the direction of extension can be controlled by the sign of applied SA. Finally, we demonstrated in vivo human retinal imaging by altering the applied SA. PMID:23082278

Optical coherence tomography in the diagnosis of actinic keratosis

DEFF Research Database (Denmark)

Friis, K B E; Themstrup, L; Jemec, G B E

2017-01-01

BACKGROUND: Optical coherence tomography (OCT) is a real-time non-invasive imaging tool, introduced in dermatology in the late 1990s. OCT uses near-infrared light impulses to produce images which can be displayed in cross-sectional and en-face mode. The technique has been used to image skin...... of layers consistent with absence of normal layered architecture in the skin. Thickened epidermis was found in 14/16 studies and white (hyperreflective) streaks and dots were described in 11/16 studies. In High-definition optical coherence tomography (HD-OCT) images disarranged epidermis (cross......-sectional images) along with an atypical honeycomb pattern (en-face images) was found in 5/5 studies and well-demarcated dermo-epithelial junction (DEJ) (cross-sectional images) was described in 3/5 studies. CONCLUSION: Several morphological characteristics of AKs were identified using Conventional OCT and HD...

Advances in optical coherence tomography in dermatology-a review

Science.gov (United States)

Olsen, Jonas; Holmes, Jon; Jemec, Gregor B. E.

2018-04-01

Optical coherence tomography (OCT) was introduced as an imaging system, but like ultrasonography, other measures, such as blood perfusion and polarization of light, have enabled the technology to approach clinical utility. This review aims at providing an overview of the advances in clinical research based on the improving technical aspects. OCT provides cross-sectional and en face images down to skin depths of 0.4 to 2.00 mm with optical resolution of 3 to 15 μm. Dynamic optical coherence tomography (D-OCT) enables the visualization of cutaneous microvasculature via detection of rapid changes in the interferometric signal of blood flow. Nonmelanoma skin cancer (NMSC) is the most comprehensively investigated topic, resulting in improved descriptions of morphological features and diagnostic criteria. A refined scoring system for diagnosing NMSC, taking findings from conventional and D-OCT into account, is warranted. OCT diagnosis of melanoma is hampered by the resolution and the optical properties of melanin. D-OCT may be of value in diseases characterized with dynamic changes in the vasculature of the skin and the addition of functional measures is strongly encouraged. In conclusion, OCT in dermatology is still an emerging technology that has great potential for improving further in the future.

Inner structure detection by optical tomography technology based on feedback of microchip Nd:YAG lasers.

Science.gov (United States)

Xu, Chunxin; Zhang, Shulian; Tan, Yidong; Zhao, Shijie

2013-05-20

We describe a new optical tomography technology based on feedback of microchip Nd:YAG lasers. In the case of feedback light frequency-shifted, light can be magnified by a fact of 10(6) in the Nd:YAG microchip lasers, which makes it possible to realize optical tomography with a greater depth than current optical tomography. The results of the measuring and imaging of kinds of samples are presented, which demonstrate the feasibility and potential of this approach in the inner structure detection. The system has a lateral resolution of ~1 μm, a vertical resolution of 15 μm and a longitudinal scanning range of over 10mm.

Fourier phase in Fourier-domain optical coherence tomography

Science.gov (United States)

Uttam, Shikhar; Liu, Yang

2015-01-01

Phase of an electromagnetic wave propagating through a sample-of-interest is well understood in the context of quantitative phase imaging in transmission-mode microscopy. In the past decade, Fourier-domain optical coherence tomography has been used to extend quantitative phase imaging to the reflection-mode. Unlike transmission-mode electromagnetic phase, however, the origin and characteristics of reflection-mode Fourier phase are poorly understood, especially in samples with a slowly varying refractive index. In this paper, the general theory of Fourier phase from first principles is presented, and it is shown that Fourier phase is a joint estimate of subresolution offset and mean spatial frequency of the coherence-gated sample refractive index. It is also shown that both spectral-domain phase microscopy and depth-resolved spatial-domain low-coherence quantitative phase microscopy are special cases of this general theory. Analytical expressions are provided for both, and simulations are presented to explain and support the theoretical results. These results are further used to show how Fourier phase allows the estimation of an axial mean spatial frequency profile of the sample, along with depth-resolved characterization of localized optical density change and sample heterogeneity. Finally, a Fourier phase-based explanation of Doppler optical coherence tomography is also provided. PMID:26831383

Fourier phase in Fourier-domain optical coherence tomography.

Science.gov (United States)

Uttam, Shikhar; Liu, Yang

2015-12-01

Phase of an electromagnetic wave propagating through a sample-of-interest is well understood in the context of quantitative phase imaging in transmission-mode microscopy. In the past decade, Fourier-domain optical coherence tomography has been used to extend quantitative phase imaging to the reflection-mode. Unlike transmission-mode electromagnetic phase, however, the origin and characteristics of reflection-mode Fourier phase are poorly understood, especially in samples with a slowly varying refractive index. In this paper, the general theory of Fourier phase from first principles is presented, and it is shown that Fourier phase is a joint estimate of subresolution offset and mean spatial frequency of the coherence-gated sample refractive index. It is also shown that both spectral-domain phase microscopy and depth-resolved spatial-domain low-coherence quantitative phase microscopy are special cases of this general theory. Analytical expressions are provided for both, and simulations are presented to explain and support the theoretical results. These results are further used to show how Fourier phase allows the estimation of an axial mean spatial frequency profile of the sample, along with depth-resolved characterization of localized optical density change and sample heterogeneity. Finally, a Fourier phase-based explanation of Doppler optical coherence tomography is also provided.

Spectral-domain optical coherence tomography staging and autofluorescence imaging in achromatopsia.

Science.gov (United States)

Greenberg, Jonathan P; Sherman, Jerome; Zweifel, Sandrine A; Chen, Royce W S; Duncker, Tobias; Kohl, Susanne; Baumann, Britta; Wissinger, Bernd; Yannuzzi, Lawrence A; Tsang, Stephen H

2014-04-01

IMPORTANCE Evidence is mounting that achromatopsia is a progressive retinal degeneration, and treatments for this condition are on the horizon. OBJECTIVES To categorize achromatopsia into clinically identifiable stages using spectral-domain optical coherence tomography and to describe fundus autofluorescence imaging in this condition. DESIGN, SETTING, AND PARTICIPANTS A prospective observational study was performed between 2010 and 2012 at the Edward S. Harkness Eye Institute, New York-Presbyterian Hospital. Participants included 17 patients (aged 10-62 years) with full-field electroretinography-confirmed achromatopsia. MAIN OUTCOMES AND MEASURES Spectral-domain optical coherence tomography features and staging system, fundus autofluorescence and near-infrared reflectance features and their correlation to optical coherence tomography, and genetic mutations served as the outcomes and measures. RESULTS Achromatopsia was categorized into 5 stages on spectral-domain optical coherence tomography: stage 1 (2 patients [12%]), intact outer retina; stage 2 (2 patients [12%]), inner segment ellipsoid line disruption; stage 3 (5 patients [29%]), presence of an optically empty space; stage 4 (5 patients [29%]), optically empty space with partial retinal pigment epithelium disruption; and stage 5 (3 patients [18%]), complete retinal pigment epithelium disruption and/or loss of the outer nuclear layer. Stage 1 patients showed isolated hyperreflectivity of the external limiting membrane in the fovea, and the external limiting membrane was hyperreflective above each optically empty space. On near infrared reflectance imaging, the fovea was normal, hyporeflective, or showed both hyporeflective and hyperreflective features. All patients demonstrated autofluorescence abnormalities in the fovea and/or parafovea: 9 participants (53%) had reduced or absent autofluorescence surrounded by increased autofluorescence, 4 individuals (24%) showed only reduced or absent autofluorescence, 3

Optical Coherence Tomography

DEFF Research Database (Denmark)

Fercher, A.F.; Andersen, Peter E.

2017-01-01

Optical coherence tomography (OCT) is a technique that is used to peer inside a body noninvasively. Tissue structure defined by tissue absorption and scattering coefficients, and the speed of blood flow, are derived from the characteristics of light remitted by the body. Singly backscattered light...... detected by partial coherence interferometry (PCI) is used to synthesize the tomographic image coded in false colors. A prerequisite of this technique is a low time-coherent but high space-coherent light source, for example, a superluminescent diode or a supercontinuum source. Alternatively, the imaging...... technique can be realized by using ultrafast wavelength scanning light sources. For tissue imaging, the light source wavelengths are restricted to the red and near-infrared (NIR) region from about 600 to 1300 nm, the so-called therapeutic window, where absorption (μa ≈ 0.01 mm−1) is small enough. Transverse...

Optical Biopsy Using Tissue Spectroscopy and Optical Coherence Tomography

Directory of Open Access Journals (Sweden)

Norman S Nishioka

2003-01-01

Full Text Available ‘Optical biopsy’ or ‘optical diagnostics’ is a technique whereby light energy is used to obtain information about the structure and function of tissues without disrupting them. In fluorescence spectroscopy, light energy (usually provided by a laser is used to excite tissues and the resulting fluorescence provides information about the target tissue. Its major gastrointestinal application has been in the evaluation of colonic polyps, in which it can reliably distinguish malignant from benign lesions. Optical coherence tomography (OCT has been used in the investigation of Barrett’s epithelium (and dysplasia, although a variety of other applications are feasible. For example, OCT could assist in the identification and staging of mucosal and submucosal neoplasms, the grading of inflammation in the stomach and intestine, the diagnosis of biliary tumours and the assessment of villous architecture. OCT differs from endoscopic ultrasound, a complementary modality, in that it has a much higher resolution but lesser depth of penetration. The images correlate with the histopathological appearance of tissues, and the addition of Doppler methods may enable it to evaluate the vascularity of tumours and the amount of blood flow in varices. Refinements in these new optical techniques will likely make them valuable in clinical practice, although their specific roles have yet to be determined.

CCD-camera-based diffuse optical tomography to study ischemic stroke in preclinical rat models

Science.gov (United States)

Lin, Zi-Jing; Niu, Haijing; Liu, Yueming; Su, Jianzhong; Liu, Hanli

2011-02-01

Stroke, due to ischemia or hemorrhage, is the neurological deficit of cerebrovasculature and is the third leading cause of death in the United States. More than 80 percent of stroke patients are ischemic stroke due to blockage of artery in the brain by thrombosis or arterial embolism. Hence, development of an imaging technique to image or monitor the cerebral ischemia and effect of anti-stoke therapy is more than necessary. Near infrared (NIR) optical tomographic technique has a great potential to be utilized as a non-invasive image tool (due to its low cost and portability) to image the embedded abnormal tissue, such as a dysfunctional area caused by ischemia. Moreover, NIR tomographic techniques have been successively demonstrated in the studies of cerebro-vascular hemodynamics and brain injury. As compared to a fiberbased diffuse optical tomographic system, a CCD-camera-based system is more suitable for pre-clinical animal studies due to its simpler setup and lower cost. In this study, we have utilized the CCD-camera-based technique to image the embedded inclusions based on tissue-phantom experimental data. Then, we are able to obtain good reconstructed images by two recently developed algorithms: (1) depth compensation algorithm (DCA) and (2) globally convergent method (GCM). In this study, we will demonstrate the volumetric tomographic reconstructed results taken from tissuephantom; the latter has a great potential to determine and monitor the effect of anti-stroke therapies.

Frequency domain fluorescent diffuse tomography of small animals with DsRed2-expressed tumors

Science.gov (United States)

Turchin, Ilya V.; Savitsky, Alexander P.; Kamensky, Vladislav A.; Plehanov, Vladimir I.; Orlova, Anna G.; Sergeeva, Ekaterina A.; Kleshnin, Mikhail S.; Shirmanova, Marina V.

2006-02-01

The main applications of fluorescent proteins (FPs) are monitoring tumor growth, angiogenesis, metastases formation and effects of new classes of drugs. Different types of tomography allow fluorescence imaging of tumors located deep in human or animal tissue. These techniques were used for investigation of the distribution of near-infrared fluorescent probes, but only a few works are devoted to fluorescence tomography in visible light. In this work, preliminary results of the frequency domain fluorescent diffuse tomography (FD FDT) method in application to DsRed2 protein as a fluorescent agent are presented. For the first step of our experiments we utilized second harmonic generation of Nd:YAG laser (532 nm) modulated by low frequency (1 kHz) in the experimental setup. The transilluminative planar configuration was used in the setup. A series of model experiments has been conducted and show good agreement between theoretical and experimental fluorescence intensity. Post mortem experiments with capsules containing DsRed2 and scattering solution introduced into esophagus of rats to simulate tumor formation have been conducted. The results of these experiments show that sensitivity of the setup is sufficient to detect DsRed2 in concentrations similar to those in FP-expressed tumor, but the contrast is not enough high to separate fluorescence of DsRed2 and surrounding tissues. The setup can be significantly improved by utilizing high-frequency modulation (110 MHz using acousto-optical modulator) of the excitation light and precise phase measurements due to difference in fluorescence life-time of FPs and surrounding tissues. An algorithm of processing a fluorescent image based on calculating zero of maximum curvature was employed for detection of fluorescent inclusions boundaries in the image.

Modeling light–tissue interaction in optical coherence tomography systems

DEFF Research Database (Denmark)

Andersen, Peter E.; Jørgensen, Thomas Martini; Thrane, Lars

2015-01-01

Optical coherence tomography (OCT) performs high-resolution, cross-sectional tomographic imaging of the internal tissue microstructure by measuring backscattered or backreflected light. The scope of this chapter is to present analytical and numerical models that are able to describe light-tissue ...

Submicron Resolution Spectral-Domain Optical Coherence Tomography

KAUST Repository

Alarousu, Erkki

2013-11-14

Apparatuses and systems for submicron resolution spectral-domain optical coherence tomography (OCT) are disclosed. The system may use white light sources having wavelengths within 400-1000 nanometers, and achieve resolution below 1 .mu.m. The apparatus is aggregated into a unitary piece, and a user can connect the apparatus to a user provided controller and/or light source. The light source may be a supercontinuum source.

Three-Dimensional Optical Coherence Tomography (3D OCT), Phase II

Data.gov (United States)

National Aeronautics and Space Administration — Applied Science Innovations, Inc. proposes a new tool of 3D optical coherence tomography (OCT) for cellular level imaging at video frame rates and dramatically...

Simultaneous topography and tomography of latent fingerprints using full-field swept-source optical coherence tomography

Science.gov (United States)

Dubey, Satish Kumar; Singh Mehta, Dalip; Anand, Arun; Shakher, Chandra

2008-01-01

We demonstrate simultaneous topography and tomography of latent fingerprints using full-field swept-source optical coherence tomography (OCT). The swept-source OCT system comprises a superluminescent diode (SLD) as broad-band light source, an acousto-optic tunable filter (AOTF) as frequency tuning device, and a compact, nearly common-path interferometer. Both the amplitude and the phase map of the interference fringe signal are reconstructed. Optical sectioning of the latent fingerprint sample is obtained by selective Fourier filtering and the topography is retrieved from the phase map. Interferometry, selective filtering, low coherence and hence better resolution are some of the advantages of the proposed system over the conventional fingerprint detection techniques. The present technique is non-invasive in nature and does not require any physical or chemical processing. Therefore, the quality of the sample does not alter and hence the same fingerprint can be used for other types of forensic test. Exploitation of low-coherence interferometry for fingerprint detection itself provides an edge over other existing techniques as fingerprints can even be lifted from low-reflecting surfaces. The proposed system is very economical and compact.

Heartbeat OCT: In vivo intravascular megahertz-optical coherence tomography

NARCIS (Netherlands)

T. Wang (Tianshi); A.F.H. Pfeiffer (Andreas); E.S. Regar (Eveline); W. Wieser (Wolfgang); H.M.M. van Beusekom (Heleen); C.T. Lancée (Charles); T. Springeling (Tirza); I. Krabbendam (Ilona); A.F.W. van der Steen (Ton); R. Huber (Roman); G. van Soest (Gijs)

2015-01-01

textabstractCardiac motion artifacts, non-uniform rotational distortion and undersampling affect the image quality and the diagnostic impact of intravascular optical coherence tomography (IV-OCT). In this study we demonstrate how these limitations of IV-OCT can be addressed by using an imaging

Quantitative study of luminescence optical tomography. Application to sources localisation in molecular imaging

International Nuclear Information System (INIS)

Boffety, Matthieu

2010-01-01

Molecular imaging is a major modality in the field of preclinical research. Among the existing methods, techniques based on optical detection of visible or near infrared radiation are the most recent and are mainly represented by luminescence optical tomography techniques. These methods allow for 3D characterization of a biological medium by reconstructing maps of concentration or localisation of luminescent beacons sensitive to biological and chemical processes at the molecular or cellular scale. Luminescence optical tomography is based on a model of light propagation in tissues, a protocol for acquiring surface signal and a numerical inversion procedure used to reconstruct the parameters of interest. This thesis is structured around these three axes and provides an answer to each problem. The main objective of this study is to introduce and present the tools to evaluate the theoretical performances of optical tomography methods. One of its major outcomes is the realisation of experimental tomographic reconstructions from images acquired by an optical imager designed for 2D planar imaging and developed by the company Quidd. In a first step we develop the theory of transport in scattering medium to establish the concept on which our work will rely. We present two different propagation models as well as resolution methods and theoretical difficulties associated with them. In a second part we introduce the statistical tools used to characterise tomographic systems. We define and apply a procedure to simple situations in luminescence optical tomography. The last part of this work presents the development of an inversion procedure. After introducing the theoretical framework we validate the procedure from numerical data before successfully applying it to experimental measurements. (author) [fr

Donor disc attachment assessment with intraoperative spectral optical coherence tomography during descemet stripping automated endothelial keratoplasty

Directory of Open Access Journals (Sweden)

Edward Wylegala

2013-01-01

Full Text Available Optical coherence tomography has already been proven to be useful for pre- and post-surgical anterior eye segment assessment, especially in lamellar keratoplasty procedures. There is no evidence for intraoperative usefulness of optical coherence tomography (OCT. We present a case report of the intraoperative donor disc attachment assessment with spectral-domain optical coherence tomography in case of Descemet stripping automated endothelial keratoplasty (DSAEK surgery combined with corneal incisions. The effectiveness of the performed corneal stab incisions was visualized directly by OCT scan analysis. OCT assisted DSAEK allows the assessment of the accuracy of the Descemet stripping and donor disc attachment.

Optical Coherence Tomography Technology and Quality Improvement Methods for Optical Coherence Tomography Images of Skin: A Short Review

OpenAIRE

Adabi, Saba; Turani, Zahra; Fatemizadeh, Emad; Clayton, Anne; Nasiriavanaki, Mohammadreza

2017-01-01

Optical coherence tomography (OCT) delivers 3-dimensional images of tissue microstructures. Although OCT imaging offers a promising high-resolution method, OCT images experience some artifacts that lead to misapprehension of tissue structures. Speckle, intensity decay, and blurring are 3 major artifacts in OCT images. Speckle is due to the low coherent light source used in the configuration of OCT. Intensity decay is a deterioration of light with respect to depth, and blurring is the conseque...

Agreement of angle closure assessments between gonioscopy, anterior segment optical coherence tomography and spectral domain optical coherence tomography

OpenAIRE

Tay, Elton Lik Tong; Yong, Vernon Khet Yau; Lim, Boon Ang; Sia, Stelson; Wong, Elizabeth Poh Ying; Yip, Leonard Wei Leon

2015-01-01

AIM: To determine angle closure agreements between gonioscopy and anterior segment optical coherence tomography (AS-OCT), as well as gonioscopy and spectral domain OCT (SD-OCT). A secondary objective was to quantify inter-observer agreements of AS-OCT and SD-OCT assessments. METHODS: Seventeen consecutive subjects (33 eyes) were recruited from the study hospital’s Glaucoma clinic. Gonioscopy was performed by a glaucomatologist masked to OCT results. OCT images were read independently by 2 ...

Application of optical coherence tomography angiography for diabetic retinopathy

Directory of Open Access Journals (Sweden)

Qing Liu

2016-04-01

Full Text Available Optical coherence tomography angiography(OCTAis a new emerging technology of the optical coherence tomography(OCTin recent years. It's a noninvasive and fast retinal vascular imaging technology with high resolution, and has been gradually applied to make diagnosis, gives treatment and follow-up for various types of retinal vascular diseases, such as diabetic retinopathy, choroid neovascularization, etc. OCTA has the unique advantages of layered observing the structure and shape of the chorioretinal vascular at different levels, and quantifying the blood flow index of designated scope and the flow area of lesions. However, OCTA requires high solid vision and good cooperation of patients, even has the limitations to observe the retinal scope and retinal vascular barrier function. With overcoming these limitations, it's helpful for us to improve the understanding of retinal vascular diseases, consummate the diagnosis and treatment and observation of retinal vascular diseases.

Ultrasound-guided diffuse optical tomography (DOT) of invasive breast carcinoma: Does tumour total haemoglobin concentration contribute to the prediction of axillary lymph node status?

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Zhu, Qingli, E-mail: qinglizhu@gmail.com [Department of Diagnostic Ultrasound, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Shuaifuyuan 1, Dongcheng District, Beijing 100730 (China); Xiao, Mengsu, E-mail: xiaomengsu_2000@sina.com [Department of Diagnostic Ultrasound, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Shuaifuyuan 1, Dongcheng District, Beijing 100730 (China); You, Shanshan, E-mail: shanshan_0531@sina.com [Department of Diagnostic Ultrasound, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Shuaifuyuan 1, Dongcheng District, Beijing 100730 (China); Zhang, Jing, E-mail: zhang.jing1029@163.com [Department of Diagnostic Ultrasound, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Shuaifuyuan 1, Dongcheng District, Beijing 100730 (China); Jiang, Yuxin, E-mail: yuxinjiangxh@yahoo.com.cn [Department of Diagnostic Ultrasound, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Shuaifuyuan 1, Dongcheng District, Beijing 100730 (China); Lai, Xingjian, E-mail: lxjpumch@yahoo.com.cn [Department of Diagnostic Ultrasound, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Shuaifuyuan 1, Dongcheng District, Beijing 100730 (China); Dai, Qing, E-mail: qingdai_2000@yahoo.com [Department of Diagnostic Ultrasound, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Shuaifuyuan 1, Dongcheng District, Beijing 100730 (China)

2012-11-15

Objectives: To prospectively study the ultrasound-guided near-infrared diffuse optical tomography (DOT) findings of the total haemoglobin concentration (THC) detected in invasive breast carcinomas and its contribution to the prediction of axillary lymph node (LN) status. Methods: A total of 195 invasive breast carcinomas were prospectively studied with DOT before surgery. Lumpectomy or mastectomy with full axillary nodal dissection was performed. Tumour size and THC level were correlated with LN status by a logistic regression analysis. Results: One hundred twenty-four patients (63.59%) was LN(-) and 71 (36.41%) was LN(+). The average THC was significantly higher in the LN(+) group than in the LN(-) group (252.94 {+-} 69.19 {mu}mol/L versus 203.86 {+-} 83.13 {mu}mol/L, P = 0.01). A multivariate analysis showed an independent relationship between the probability of axillary metastasis, elevated THC level (P = 0.01), and tumour size (P = 0.001). The odds ratio with THC {>=} 140 {mu}mol/L was 13.651 (1.781-104.560), whereas that of tumour size with a 1 cm increment was only 1.777 (1.283-2.246). Conclusions: The THC level and the tumour size are independent and preoperative predictors of axillary nodal status; these variables may improve the diagnosis of patients with lymph node metastasis.

Effect of Shot Noise on Simultaneous Sensing in Frequency Division Multiplexed Diffuse Optical Tomographic Imaging Process.

Science.gov (United States)

Jang, Hansol; Lim, Gukbin; Hong, Keum-Shik; Cho, Jaedu; Gulsen, Gultekin; Kim, Chang-Seok

2017-11-28

Diffuse optical tomography (DOT) has been studied for use in the detection of breast cancer, cerebral oxygenation, and cognitive brain signals. As optical imaging studies have increased significantly, acquiring imaging data in real time has become increasingly important. We have developed frequency-division multiplexing (FDM) DOT systems to analyze their performance with respect to acquisition time and imaging quality, in comparison with the conventional time-division multiplexing (TDM) DOT. A large tomographic area of a cylindrical phantom 60 mm in diameter could be successfully reconstructed using both TDM DOT and FDM DOT systems. In our experiment with 6 source-detector (S-D) pairs, the TDM DOT and FDM DOT systems required 6.18 and 1 s, respectively, to obtain a single tomographic data set. While the absorption coefficient of the reconstruction image was underestimated in the case of the FDM DOT, we experimentally confirmed that the abnormal region can be clearly distinguished from the background phantom using both methods.

Effect of Shot Noise on Simultaneous Sensing in Frequency Division Multiplexed Diffuse Optical Tomographic Imaging Process

Directory of Open Access Journals (Sweden)

Hansol Jang

2017-11-01

Full Text Available Diffuse optical tomography (DOT has been studied for use in the detection of breast cancer, cerebral oxygenation, and cognitive brain signals. As optical imaging studies have increased significantly, acquiring imaging data in real time has become increasingly important. We have developed frequency-division multiplexing (FDM DOT systems to analyze their performance with respect to acquisition time and imaging quality, in comparison with the conventional time-division multiplexing (TDM DOT. A large tomographic area of a cylindrical phantom 60 mm in diameter could be successfully reconstructed using both TDM DOT and FDM DOT systems. In our experiment with 6 source-detector (S-D pairs, the TDM DOT and FDM DOT systems required 6.18 and 1 s, respectively, to obtain a single tomographic data set. While the absorption coefficient of the reconstruction image was underestimated in the case of the FDM DOT, we experimentally confirmed that the abnormal region can be clearly distinguished from the background phantom using both methods.

The fundus photo has met its match: optical coherence tomography and adaptive optics ophthalmoscopy are here to stay.

Science.gov (United States)

Morgan, Jessica I W

2016-05-01

Over the past 25 years, optical coherence tomography (OCT) and adaptive optics (AO) ophthalmoscopy have revolutionised our ability to non-invasively observe the living retina. The purpose of this review is to highlight the techniques and human clinical applications of recent advances in OCT and adaptive optics scanning laser/light ophthalmoscopy (AOSLO) ophthalmic imaging. Optical coherence tomography retinal and optic nerve head (ONH) imaging technology allows high resolution in the axial direction resulting in cross-sectional visualisation of retinal and ONH lamination. Complementary AO ophthalmoscopy gives high resolution in the transverse direction resulting in en face visualisation of retinal cell mosaics. Innovative detection schemes applied to OCT and AOSLO technologies (such as spectral domain OCT, OCT angiography, confocal and non-confocal AOSLO, fluorescence, and AO-OCT) have enabled high contrast between retinal and ONH structures in three dimensions and have allowed in vivo retinal imaging to approach that of histological quality. In addition, both OCT and AOSLO have shown the capability to detect retinal reflectance changes in response to visual stimuli, paving the way for future studies to investigate objective biomarkers of visual function at the cellular level. Increasingly, these imaging techniques are being applied to clinical studies of the normal and diseased visual system. Optical coherence tomography and AOSLO technologies are capable of elucidating the structure and function of the retina and ONH noninvasively with unprecedented resolution and contrast. The techniques have proven their worth in both basic science and clinical applications and each will continue to be utilised in future studies for many years to come. © 2016 The Authors Ophthalmic & Physiological Optics © 2016 The College of Optometrists.

Simultaneous measurement of group refractive index and thickness of optical samples using optical coherence tomography

International Nuclear Information System (INIS)

Cheng, Hsu-Chih; Liu, Yi-Cheng

2010-01-01

Optical coherence tomography (OCT), based on a Michelson interferometer and utilizing low coherence light as the optical source, is a novel technique for the noninvasive imaging of optical scattering media. A simple OCT scheme based on a 3x3 fiber coupler is presented for the simultaneous measurement of the refractive index and thickness of optical samples. The proposed system enables the refractive index and thickness to be determined without any prior knowledge of the sample parameters and is characterized by a simple and compact configuration, a straightforward measurement procedure, and a low cost. The feasibility of the proposed approach is demonstrated experimentally using BK7 and B270 optical glass samples.

Surface diffusion studies by optical diffraction techniques

International Nuclear Information System (INIS)

Xiao, X.D.

1992-11-01

The newly developed optical techniques have been combined with either second harmonic (SH) diffraction or linear diffraction off a monolayer adsorbate grating for surface diffusion measurement. Anisotropy of surface diffusion of CO on Ni(l10) was used as a demonstration for the second harmonic dim reaction method. The linear diffraction method, which possesses a much higher sensitivity than the SH diffraction method, was employed to study the effect of adsorbate-adsorbate interaction on CO diffusion on Ni(l10) surface. Results showed that only the short range direct CO-CO orbital overlapping interaction influences CO diffusion but not the long range dipole-dipole and CO-NI-CO interactions. Effects of impurities and defects on surface diffusion were further explored by using linear diffraction method on CO/Ni(110) system. It was found that a few percent S impurity can alter the CO diffusion barrier height to a much higher value through changing the Ni(110) surface. The point defects of Ni(l10) surface seem to speed up CO diffusion significantly. A mechanism with long jumps over multiple lattice distance initiated by CO filled vacancy is proposed to explain the observed defect effect

Time evolution of negative binomial optical field in a diffusion channel

International Nuclear Information System (INIS)

Liu Tang-Kun; Wu Pan-Pan; Shan Chuan-Jia; Liu Ji-Bing; Fan Hong-Yi

2015-01-01

We find the time evolution law of a negative binomial optical field in a diffusion channel. We reveal that by adjusting the diffusion parameter, the photon number can be controlled. Therefore, the diffusion process can be considered a quantum controlling scheme through photon addition. (paper)

Diffusion-weighted MRI in acute posterior ischemic optic neuropathy

International Nuclear Information System (INIS)

Srinivasan, Sivasubramanian; Moorthy, Srikant; Sreekumar, KP; Kulkarni, Chinmay

2012-01-01

Blindness following surgery, especially cardiac surgery, has been reported sporadically, the most common cause being ischemic optic neuropathy. The role of MRI in the diagnosis of this condition is not well established. We present a case of postoperative posterior ischemic optic neuropathy that was diagnosed on diffusion-weighted MRI

Optical coherence tomography in gastroenterology: a review and future outlook

Science.gov (United States)

Tsai, Tsung-Han; Leggett, Cadman L.; Trindade, Arvind J.; Sethi, Amrita; Swager, Anne-Fré; Joshi, Virendra; Bergman, Jacques J.; Mashimo, Hiroshi; Nishioka, Norman S.; Namati, Eman

2017-12-01

Optical coherence tomography (OCT) is an imaging technique optically analogous to ultrasound that can generate depth-resolved images with micrometer-scale resolution. Advances in fiber optics and miniaturized actuation technologies allow OCT imaging of the human body and further expand OCT utilization in applications including but not limited to cardiology and gastroenterology. This review article provides an overview of current OCT development and its clinical utility in the gastrointestinal tract, including disease detection/differentiation and endoscopic therapy guidance, as well as a discussion of its future applications.

Corneal thickness and elevation measurements using swept-source optical coherence tomography and slit scanning topography in normal and keratoconic eyes.

Science.gov (United States)

Jhanji, Vishal; Yang, Bingzhi; Yu, Marco; Ye, Cong; Leung, Christopher K S

2013-11-01

To compare corneal thickness and corneal elevation using swept source optical coherence tomography and slit scanning topography. Prospective study. 41 normal and 46 keratoconus subjects. All eyes were imaged using swept source optical coherence tomography and slit scanning tomography during the same visit. Mean corneal thickness and best-fit sphere measurements were compared between the instruments. Agreement of measurements between swept source optical coherence tomography and scanning slit topography was analyzed. Intra-rater reproducibility coefficient and intraclass correlation coefficient were evaluated. In normal eyes, central corneal thickness measured by swept source optical coherence tomography was thinner compared with slit scanning topography (p topography. In keratoconus eyes, central corneal thickness was thinner on swept source optical coherence tomography than slit scanning topography (p = 0.081) and ultrasound pachymetry (p = 0.001). There were significant differences between thinnest corneal thickness, and, anterior and posterior best-fit sphere measurements between both instruments (p topography. With better reproducibility coefficients and intraclass correlation coefficients, swept source optical coherence tomography may provide a reliable alternative for measurement of corneal parameters. © 2013 The Authors. Clinical and Experimental Ophthalmology © 2013 Royal Australian and New Zealand College of Ophthalmologists.

Contribution of optical coherence tomography imaging in management of iatrogenic coronary dissection

Energy Technology Data Exchange (ETDEWEB)

Barber-Chamoux, Nicolas, E-mail: nbarber-chamoux@chu-clermontferrand.fr [Department of Cardiology, Gabriel Montpied University Hospital, Clermont-Ferrand (France); Souteyrand, Géraud; Combaret, Nicolas [Department of Cardiology, Gabriel Montpied University Hospital, Clermont-Ferrand (France); ISIT, CaVITI, CNRS (UMR-6284), Auvergne University, Clermont-Ferrand (France); Ouedraogo, Edgar; Lusson, Jean René [Department of Cardiology, Gabriel Montpied University Hospital, Clermont-Ferrand (France); Motreff, Pascal [Department of Cardiology, Gabriel Montpied University Hospital, Clermont-Ferrand (France); ISIT, CaVITI, CNRS (UMR-6284), Auvergne University, Clermont-Ferrand (France)

2016-03-15

Iatrogenic coronary dissection is a rare but potentially serious complication of coronary angiography and angioplasty. Treatment with angioplasty guided only by angiography is often difficult. Optical coherence tomography imaging seems to be an interesting technique to lead the management of iatrogenic coronary dissection. Diagnosis can be made by optical coherence tomography; it can also eliminate differential diagnosis. Furthermore, this technique can guide safely the endovascular treatment. - Highlights: • Iatrogenic coronary dissection remains a challenging problem in angiography. • Endocoronary imaging is helpful for the diagnosis of iatrogenic coronary dissection. • OCT is a safe option to manage the endovascular treatment of coronary dissection.

Early detection of tooth wear by en-face optical coherence tomography

Science.gov (United States)

Mărcăuteanu, Corina; Negrutiu, Meda; Sinescu, Cosmin; Demjan, Eniko; Hughes, Mike; Bradu, Adrian; Dobre, George; Podoleanu, Adrian G.

2009-02-01

Excessive dental wear (pathological attrition and/or abfractions) is a frequent complication in bruxing patients. The parafunction causes heavy occlusal loads. The aim of this study is the early detection and monitoring of occlusal overload in bruxing patients. En-face optical coherence tomography was used for investigating and imaging of several extracted tooth, with a normal morphology, derived from patients with active bruxism and from subjects without parafunction. We found a characteristic pattern of enamel cracks in patients with first degree bruxism and with a normal tooth morphology. We conclude that the en-face optical coherence tomography is a promising non-invasive alternative technique for the early detection of occlusal overload, before it becomes clinically evident as tooth wear.

Spectral domain optical coherence tomography morphology in optic disc pit associated maculopathy

Directory of Open Access Journals (Sweden)

Janusz Michalewski

2014-01-01

Full Text Available Purpose: Our purpose was to study the clinical manifestation and course of optic pit maculopathy using Spectral Domain Optical Coherence Tomography (SD- OCT images. Materials and Methods: We used SD-OCT to examine 20 eyes of 19 patients with a macular detachment in combination with an optic. Results: We observed five different fovea appearances in regard to fluid localization. In five eyes, we recorded changes in the fluid distribution with SD-OCT. In 17/20 eyes, we noted a communication between the perineural and subretinal and/or intraretinal space at the margin of the optic disc. Conclusion: 3-dimensional SD-OCT (3D-SDOCT scans revealed a three-fold connection, between subretinal and intraretinal space, perineural space, and the vitreous cavity. Therefore, we suppose that intraretinal or subretinal fluid in optic pit maculopathy may have both a vitreous and cerebrospinal origin. A membrane, covering the optic nerve was noted in 14 cases. Even if it seems intact in some B-scans, it is not complete in others several micrometers apart. Additionally, we observed fluid accumulation below the margin of the optic disc and hyperreflective porous tissue in the optic disc excavation. Those findings do not influence the course of maculopathy.

Towards the use of bioresorbable fibers in time-domain diffuse optics.

Science.gov (United States)

Di Sieno, Laura; Boetti, Nadia G; Dalla Mora, Alberto; Pugliese, Diego; Farina, Andrea; Konugolu Venkata Sekar, Sanathana; Ceci-Ginistrelli, Edoardo; Janner, Davide; Pifferi, Antonio; Milanese, Daniel

2018-01-01

In the last years bioresorbable materials are gaining increasing interest for building implantable optical components for medical devices. In this work we show the fabrication of bioresorbable optical fibers designed for diffuse optics applications, featuring large core diameter (up to 200 μm) and numerical aperture (0.17) to maximize the collection efficiency of diffused light. We demonstrate the suitability of bioresorbable fibers for time-domain diffuse optical spectroscopy firstly checking the intrinsic performances of the setup by acquiring the instrument response function. We then validate on phantoms the use of bioresorbable fibers by applying the MEDPHOT protocol to assess the performance of the system in measuring optical properties (namely, absorption and scattering coefficients) of homogeneous media. Further, we show an ex-vivo validation on a chicken breast by measuring the absorption and scattering spectra in the 500-1100 nm range using interstitially inserted bioresorbable fibers. This work represents a step toward a new way to look inside the body using optical fibers that can be implanted in patients. These fibers could be useful either for diagnostic (e. g. for monitoring the evolution after surgical interventions) or treatment (e. g. photodynamic therapy) purposes. Picture: Microscopy image of the 100 μm core bioresorbable fiber. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Two-color interpolation of the absorption response for quantitative acousto-optic imaging

DEFF Research Database (Denmark)

Bocoum, Maimouna; Gennisson, Jean Luc; Venet, Caroline

2018-01-01

Diffuse optical tomography (DOT) is a reliable and widespread technique for monitoring qualitative changes in absorption inside highly scattering media. It has been shown, however, that acousto-optic (AO) imaging can provide significantly more qualitative information without the need for inversio...

Advanced integrated spectrometer designs for miniaturized optical coherence tomography systems

NARCIS (Netherlands)

Akça, B.I.; Povazay, B.; Chang, Lantian; Alex, A.; Worhoff, Kerstin; de Ridder, R.M.; Drexler, W.; Pollnau, Markus

Optical coherence tomography (OCT) has enabled clinical applications that revolutionized in vivo medical diagnostics. Nevertheless, its current limitations owing to cost, size, complexity, and the need for accurate alignment must be overcome by radically novel approaches. Exploiting integrated

Optical coherence tomography in otolaryngology: original results and review of the literature

Science.gov (United States)

Bibas, Athanasios G.; Podoleanu, Adrian Gh.; Cucu, Radu G.; Dobre, George M.; Odell, Edward; Boxer, Aaron B.; O'Connors, Alec F.; Gleeson, Michael J.

2004-07-01

Optical coherence tomography is a diagnostic imaging technique allowing two dimensional tomographic imaging of tissue architecture. This is a review article on the use of optical coherence tomography in Otolaryngology including original images from human laryngeal tissue and temporal bones (cochlea) in our laboratory. Tissue specimens from normal larynges were imaged with an 850 nm OCT system. Our results showed good correlation between OCT image s and the corresponding haematoxylin-eosin stained histology sections in the normal larynx. Human temporal bones were also imaged using an 1300 nm OCT system. Limited morphological details were obtained due to the high scattering properties of the bony labyrinth.

Clinical manifestations of optic pit maculopathy as demonstrated by spectral domain optical coherence tomography

Directory of Open Access Journals (Sweden)

Tzu JH

2013-01-01

Full Text Available Jonathan H Tzu, Harry W Flynn Jr, Audina M Berrocal, William E Smiddy, Timothy G Murray, Yale L FisherDepartment of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USAPurpose: The purpose of this retrospective study was to evaluate the characteristic features, including spectral-domain optical coherence tomography (SD-OCT, clinical course, and outcome of treatment if given for patients with optic disc pit maculopathy.Methods: We investigated a consecutive series of patients with a diagnosis of optic pit maculopathy treated between 2001 and 2012 at the Bascom Palmer Eye Institute. Patients were divided into two main groups, ie, patients who were observed without surgery and patients who received surgical intervention. The main outcome measures were presenting and final visual acuity, and changes in SD-OCT imaging were recorded. Other data including age, gender, eye, age of onset, length of follow-up, location of optic pit, and location of fluid by OCT were also recorded.Results: On OCT, 67% (12/18 of the eyes showed schisis-like cavities, 22% (4/18 had only subretinal fluid, and 17% (3/18 had only a schisis-like cavity without subretinal fluid. In the patients managed by observation, visual acuity was ≥20/200 in 6/8 eyes initially and 6/8 eyes at last follow-up. Ten of 18 patients received either focal laser, surgery or both. Six of 10 eyes undergoing surgery had initial visual acuity ≥ 20/200, and 8 of 10 eyes undergoing surgery had a visual acuity of ≥20/200 at last follow-up.Conclusion: In this study, many eyes were observed and remained stable during follow-up. In eyes with reduced vision, surgical intervention produced variable outcomes, and persistent intraretinal/subretinal fluid was a common occurrence.Keywords: optic pit maculopathy, spectral-domain optical coherence tomography

Signal filtering algorithm for depth-selective diffuse optical topography

International Nuclear Information System (INIS)

Fujii, M; Nakayama, K

2009-01-01

A compact filtered backprojection algorithm that suppresses the undesirable effects of skin circulation for near-infrared diffuse optical topography is proposed. Our approach centers around a depth-selective filtering algorithm that uses an inverse problem technique and extracts target signals from observation data contaminated by noise from a shallow region. The filtering algorithm is reduced to a compact matrix and is therefore easily incorporated into a real-time system. To demonstrate the validity of this method, we developed a demonstration prototype for depth-selective diffuse optical topography and performed both computer simulations and phantom experiments. The results show that the proposed method significantly suppresses the noise from the shallow region with a minimal degradation of the target signal.

The collagen structure of equine articular cartilage, characterized using polarization-sensitive optical coherence tomography

International Nuclear Information System (INIS)

Ugryumova, Nadya; Attenburrow, Don P; Winlove, C Peter; Matcher, Stephen J

2005-01-01

Optical coherence tomography and polarization-sensitive optical coherence tomography images of equine articular cartilage are presented. Measurements were made on intact joint surfaces. Significant (e.g. x 2) variations in the intrinsic birefringence were found over spatial scales of a few millimetres, even on samples taken from young (18 month) animals that appeared visually homogeneous. A comparison of data obtained on a control tissue (equine flexor tendon) further suggests that significant variations in the orientation of the collagen fibres relative to the plane of the joint surface exist. Images of visually damaged cartilage tissue show characteristic features both in terms of the distribution of optical scatterers and of the birefringent components

The collagen structure of equine articular cartilage, characterized using polarization-sensitive optical coherence tomography

Energy Technology Data Exchange (ETDEWEB)

Ugryumova, Nadya; Attenburrow, Don P; Winlove, C Peter; Matcher, Stephen J [Biomedical Physics Group, School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL (United Kingdom)

2005-08-07

Optical coherence tomography and polarization-sensitive optical coherence tomography images of equine articular cartilage are presented. Measurements were made on intact joint surfaces. Significant (e.g. x 2) variations in the intrinsic birefringence were found over spatial scales of a few millimetres, even on samples taken from young (18 month) animals that appeared visually homogeneous. A comparison of data obtained on a control tissue (equine flexor tendon) further suggests that significant variations in the orientation of the collagen fibres relative to the plane of the joint surface exist. Images of visually damaged cartilage tissue show characteristic features both in terms of the distribution of optical scatterers and of the birefringent components.

FABRICATION OF TISSUE-SIMULATIVE PHANTOMS AND CAPILLARIES AND THEIR INVESTIGATION BY OPTICAL COHERENCE TOMOGRAPHY TECHNIQUES

Directory of Open Access Journals (Sweden)

A. V. Bykov

2013-03-01

Full Text Available Methods of tissue-simulative phantoms and capillaries fabrication from PVC-plastisol and silicone for application as test-objects in optical coherence tomography (OCT and skin and capillary emulation are considered. Comparison characteristics of these materials and recommendations for their application are given. Examples of phantoms visualization by optical coherence tomography method are given. Possibility of information using from B-scans for refractive index evaluation is shown.

Diffuse correlation tomography reveals spatial and temporal difference in blood flow changes among murine femoral grafts

Science.gov (United States)

Han, Songfeng; Proctor, Ashley R.; Benoit, Danielle S. W.; Choe, Regine

2017-07-01

Diffuse correlation tomography was utilized to noninvasively monitor 3D blood flow changes in three types of healing mouse femoral grafts. Results reveal the spatial and temporal difference among the groups.

Optical coherence tomography: technology and applications (biological and medical physics, biomedical engineering)

CERN Document Server

2013-01-01

Optical coherence tomography (OCT) is the optical analog of ultrasound imaging and is emerging as a powerful imaging technique that enables non-invasive, in vivo, high resolution, cross-sectional imaging in biological tissue. This book introduces OCT technology and applications not only from an optical and technological viewpoint, but also from biomedical and clinical perspectives. The chapters are written by leading research groups, in a style comprehensible to a broad audience.

EDITORIAL: Optical tomography and digital holography

Science.gov (United States)

Coupland, Jeremy; Lobera, Julia

2008-07-01

the resolution now places a limit on the size of the object that can be recorded. Some 60 years after the pioneering work of Gabor, digital imaging and associated computer technology offers a step change in capability with which to further exploit holography. Modern image sensors are now available with almost 30 million photosensitive elements, which corresponds to a staggering 100-fold increase compared to standard television images. At the same time personal computers have been optimized for imaging and graphics applications and this allows more sophisticated algorithms to be used in the reconstruction process. Although resolution still falls short of the materials used for optical holography, the ability to process data numerically generally outweighs this drawback and presents us with a host of new opportunities. Faced with the ability to record and process holograms numerically, it is natural to ask the question 'what information is present within recordings of scattered light?'. In fact this question could be posed by anyone using light, or indeed any other wave disturbance, for measurement purposes. For the case of optical holography, Wolf published his answer in 1969 [6], showing that for the case of weak scattering (small perturbations) and plane wave illumination, the amplitude and phase of each plane wave within the scattered field are proportional to those of a periodic variation in the refractive index contrast (i.e. a Bragg grating). This Fourier decomposition of the object was published almost simultaneously by Dandliker and Weiss [7], who also provided a graphical illustration of the technique. These works are the basis of optical tomography and provide us with the link between holographic data and 3D form. Digital holographic reconstruction and optical tomography was the theme of an international workshop [8] held in Loughborough in 2007, and many of the topics debated at the workshop have become the subject of the papers in this issue. In general

Measurement of Retinalamin diffusion coefficient in human sclera by optical spectroscopy

Science.gov (United States)

Genina, Elina A.; Bashkatov, Alexey N.; Zubkova, Elena A.; Kamenskikh, Tatiana G.; Tuchin, Valery V.

2008-12-01

The use of cytomedines (such as Retinalamin) in clinical practice has shown high effectiveness of the medicaments in ophthalmology. The study of diffusion of Retinalamin in scleral tissue is important for estimation of a drug dose delivered into inner tissue of eye, time of drug action, etc. In vitro measurements of spectral reflectance of sclera interacting with aqueous solution of Retinalamin have been carried out. Ten human sclera samples were included in the study. The results of the experiments have shown that penetration of Retinalamin into scleral tissue leads to the decrease of scleral reflectance due to optical immersion. Estimation of diffusion coefficient of studied solution has been made on the basis of analysis of optical reflectance dynamics of the sclera samples. The diffusion coefficient of Retinalamin in human scleral tissue was evaluated as (1.82±0.14)×10 -6 cm 2/s. The results are important for treatment of partial optic atrophy observed at primary open-angle glaucoma and others eye diseases.

In vivo endoscopic multi-beam optical coherence tomography

Energy Technology Data Exchange (ETDEWEB)

Standish, Beau A; Mariampillai, Adrian; Munce, Nigel R; Leung, Michael K K; Vitkin, I Alex [Deptartment of Medical Biophysics, University of Toronto, Toronto (Canada); Lee, Kenneth K C; Yang, Victor X D [Ontario Cancer Institute/University Health Network, Toronto (Canada)], E-mail: standish@ee.ryerson.ca

2010-02-07

A multichannel optical coherence tomography (multi-beam OCT) system and an in vivo endoscopic imaging probe were developed using a swept-source OCT system. The distal optics were micro-machined to produce a high numerical aperture, multi-focus fibre optic array. This combination resulted in a transverse design resolution of <10 {mu}m full width half maximum (FWHM) throughout the entire imaging range, while also increasing the signal intensity within the focus of the individual channels. The system was used in a pre-clinical rabbit study to acquire in vivo structural images of the colon and ex vivo images of the oesophagus and trachea. A good correlation between the structural multi-beam OCT images and H and E histology was achieved, demonstrating the feasibility of this high-resolution system and its potential for in vivo human endoscopic imaging.

In vivo endoscopic multi-beam optical coherence tomography

International Nuclear Information System (INIS)

Standish, Beau A; Mariampillai, Adrian; Munce, Nigel R; Leung, Michael K K; Vitkin, I Alex; Lee, Kenneth K C; Yang, Victor X D

2010-01-01

A multichannel optical coherence tomography (multi-beam OCT) system and an in vivo endoscopic imaging probe were developed using a swept-source OCT system. The distal optics were micro-machined to produce a high numerical aperture, multi-focus fibre optic array. This combination resulted in a transverse design resolution of <10 μm full width half maximum (FWHM) throughout the entire imaging range, while also increasing the signal intensity within the focus of the individual channels. The system was used in a pre-clinical rabbit study to acquire in vivo structural images of the colon and ex vivo images of the oesophagus and trachea. A good correlation between the structural multi-beam OCT images and H and E histology was achieved, demonstrating the feasibility of this high-resolution system and its potential for in vivo human endoscopic imaging.

Imaging of macrophage dynamics with optical coherence tomography in anterior ischemic optic neuropathy.

Science.gov (United States)

Kokona, Despina; Häner, Nathanael U; Ebneter, Andreas; Zinkernagel, Martin S

2017-01-01

Anterior ischemic optic neuropathy (AION) is a relatively common cause of visual loss and results from hypoperfusion of the small arteries of the anterior portion of the optic nerve. AION is the leading cause of sudden optic nerve related vision loss with approximately 10 cases per 100'000 in the population over 50 years. To date there is no established treatment for AION and therefore a better understanding of the events occurring at the level of the optic nerve head (ONH) would be important to design future therapeutic strategies. The optical properties of the eye allow imaging of the optic nerve in vivo, which is a part of the CNS, during ischemia. Experimentally laser induced optic neuropathy (eLiON) displays similar anatomical features as anterior ischemic optic neuropathy in humans. After laser induced optic neuropathy we show that hyperreflective dots in optical coherence tomography correspond to mononuclear cells in histology. Using fluorescence-activated flow cytometry (FACS) we found these cells to peak one week after eLiON. These observations were translated to OCT findings in patients with AION, where similar dynamics of hyperreflective dots at the ONH were identified. Our data suggests that activated macrophages can be identified as hyperreflective dots in OCT. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Nanoparticles displacement analysis using optical coherence tomography

Science.gov (United States)

StrÄ kowski, Marcin R.; Kraszewski, Maciej; StrÄ kowska, Paulina

2016-03-01

Optical coherence tomography (OCT) is a versatile optical method for cross-sectional and 3D imaging of biological and non-biological objects. Here we are going to present the application of polarization sensitive spectroscopic OCT system (PS-SOCT) for quantitative measurements of materials containing nanoparticles. The PS-SOCT combines the polarization sensitive analysis with time-frequency analysis. In this contribution the benefits of using the combination of timefrequency and polarization sensitive analysis are being expressed. The usefulness of PS-SOCT for nanoparticles evaluation is going to be tested on nanocomposite materials with TiO2 nanoparticles. The OCT measurements results have been compared with SEM examination of the PMMA matrix with nanoparticles. The experiment has proven that by the use of polarization sensitive and spectroscopic OCT the nanoparticles dispersion and size can be evaluated.

Diffuse Reflectance Spectroscopy of Human Skin Using a Commercial Fiber Optic Spectrometer

International Nuclear Information System (INIS)

Atencio, J. A. Delgado; Rodriguez, M. Cunill; Montiel, S. Vazquez y; Castro, Jorge; Rodriguez, A. Cornejo; Gutierrez, J. L.; Martinez, F.; Gutierrez, B.; Orozco, E.

2008-01-01

Diffuse reflectance spectroscopy is a reliable and easy to implement technique in human tissue characterization. In this work we evaluate the performance of the commercial USB4000 miniature fiber optic spectrometer in the in-vivo measurement of the diffuse reflectance spectra of different healthy skin sites and lesions in a population of 54 volunteers. Results show, that this spectrometer reproduces well the typical signatures of skin spectra over the 400-1000 nm region. Remarkable spectral differences exist between lesions and normal surrounding skin. A diffusion-based model was used to simulate reflectance spectra collected by the optical probe of the system

High-speed optical coherence tomography signal processing on GPU

International Nuclear Information System (INIS)

Li Xiqi; Shi Guohua; Zhang Yudong

2011-01-01

The signal processing speed of spectral domain optical coherence tomography (SD-OCT) has become a bottleneck in many medical applications. Recently, a time-domain interpolation method was proposed. This method not only gets a better signal-to noise ratio (SNR) but also gets a faster signal processing time for the SD-OCT than the widely used zero-padding interpolation method. Furthermore, the re-sampled data is obtained by convoluting the acquired data and the coefficients in time domain. Thus, a lot of interpolations can be performed concurrently. So, this interpolation method is suitable for parallel computing. An ultra-high optical coherence tomography signal processing can be realized by using graphics processing unit (GPU) with computer unified device architecture (CUDA). This paper will introduce the signal processing steps of SD-OCT on GPU. An experiment is performed to acquire a frame SD-OCT data (400A-linesx2048 pixel per A-line) and real-time processed the data on GPU. The results show that it can be finished in 6.208 milliseconds, which is 37 times faster than that on Central Processing Unit (CPU).

Clinical experiences with optical coherence tomography in epithelial (pre)malignancies

NARCIS (Netherlands)

Wessels, R.

2015-01-01

This thesis describes the potential of optical coherence tomography (OCT) to differentiate between normal tissue and (pre)malignant tissue in epithelial cancers. It can be divided in research performed in the genital area and the field of melanoma. Chapter 2 describes the principles of the

Oxygenation level and hemoglobin concentration in experimental tumor estimated by diffuse optical spectroscopy

Science.gov (United States)

Orlova, A. G.; Kirillin, M. Yu.; Volovetsky, A. B.; Shilyagina, N. Yu.; Sergeeva, E. A.; Golubiatnikov, G. Yu.; Turchin, I. V.

2017-07-01

Using diffuse optical spectroscopy the level of oxygenation and hemoglobin concentration in experimental tumor in comparison with normal muscle tissue of mice have been studied. Subcutaneously growing SKBR-3 was used as a tumor model. Continuous wave fiber probe diffuse optical spectroscopy system was employed. Optical properties extraction approach was based on diffusion approximation. Decreased blood oxygen saturation level and increased total hemoglobin content were demonstrated in the neoplasm. The main reason of such differences between tumor and norm was significant elevation of deoxyhemoglobin concentration in SKBR-3. The method can be useful for diagnosis of tumors as well as for study of blood flow parameters of tumor models with different angiogenic properties.

Size dependent diffusive parameters and tensorial diffusion equations in neutronic models for optically small nuclear systems

International Nuclear Information System (INIS)

Premuda, F.

1983-01-01

Two lines in improved neutron diffusion theory extending the efficiency of finite-difference diffusion codes to the field of optically small systems, are here reviewed. The firs involves the nodal solution for tensorial diffusion equation in slab geometry and tensorial formulation in parallelepiped and cylindrical gemometry; the dependence of critical eigenvalue from small slab thicknesses is also analitically investigated and finally a regularized tensorial diffusion equation is derived for slab. The other line refer to diffusion models formally unchanged with respect to the classical one, but where new size-dependent RTGB definitions for diffusion parameters are adopted, requiring that they allow to reproduce, in diffusion approach, the terms of neutron transport global balance; the trascendental equation for the buckling, arising in slab, sphere and parallelepiped geometry from the above requirement, are reported and the sizedependence of the new diffusion coefficient and extrapolated end point is investigated

Evolution of optic nerve and retina alterations in a child with indirect traumatic neuropathy as assessed by optical coherence tomography

Directory of Open Access Journals (Sweden)

Julia Dutra Rossetto

Full Text Available ABSTRACT Herein, we describe the case of a 4-year-old child with indirect traumatic optic neuropathy and serial changes of the optic nerve head and retinal nerve fiber layer (RNFL documented using optical coherence tomography (OCT. Visual acuity improved despite progressive RNFL thinning and optic disc pallor. We concluded that OCT may be useful for monitoring axonal loss but may not predict the final visual outcome.

Dental imaging using laminar optical tomography and micro CT

Science.gov (United States)

Long, Feixiao; Ozturk, Mehmet S.; Intes, Xavier; Kotha, Shiva

2014-02-01

Dental lesions located in the pulp are quite difficult to identify based on anatomical contrast, and, hence, to diagnose using traditional imaging methods such as dental CT. However, such lesions could lead to functional and/or molecular optical contrast. Herein, we report on the preliminary investigation of using Laminar Optical Tomography (LOT) to image the pulp and root canals in teeth. LOT is a non-contact, high resolution, molecular and functional mesoscopic optical imaging modality. To investigate the potential of LOT for dental imaging, we injected an optical dye into ex vivo teeth samples and imaged them using LOT and micro-CT simultaneously. A rigid image registration between the LOT and micro-CT reconstruction was obtained, validating the potential of LOT to image molecular optical contrast deep in the teeth with accuracy, non-invasively. We demonstrate that LOT can retrieve the 3D bio-distribution of molecular probes at depths up to 2mm with a resolution of several hundred microns in teeth.

Three-dimensional diffuse optical mammography with ultrasound localization in a human subject

Science.gov (United States)

Holboke, Monica J.; Tromberg, Bruce J.; Li, Xingde; Shah, Natasha; Fishkin, Joshua B.; Kidney, D.; Butler, J.; Chance, Britton; Yodh, Arjun G.

2000-04-01

We describe an approach that combines clinical ultrasound and photon migration techniques to enhance the sensitivity and information content of diffuse optical tomography. Measurements were performed on a postmenopausal woman with a single 1.8 X 0.9 cm malignant ductal carcinoma in situ approximately 7.4 mm beneath the skin surface (UCI IRB protocol 95-563). The ultrasound-derived information about tumor geometry enabled us to segment the breast tissue into tumor and background regions. Optical data was obtained with a multifrequency, multiwavelength hand-held frequency-domain photon migration backscattering probe. The optical properties of the tumor and background were then computed using the ultrasound-derived geometrical constraints. An iterative perturbative approach, using parallel processing, provided quantitative information about scattering and absorption simultaneously with the ability to incorporate and resolve complex boundary conditions and geometries. A three to four fold increase in the tumor absorption coefficient and nearly 50% reduction in scattering coefficient relative to background was observed ((lambda) equals 674, 782, 803, and 849 nm). Calculations of the mean physiological parameters reveal fourfold greater tumor total hemoglobin concentration [Hbtot] than normal breast (67 (mu) M vs 16 (mu) M) and tumor hemoglobin oxygen saturation (SOx) values of 63% (vs 73% and 68% in the region surrounding the tumor and the opposite normal tissue, respectively). Comparison of semi-infinite to heterogeneous models shows superior tumor/background contrast for the latter in both absorption and scattering. Sensitivity studies assessing the impact of tumor size and refractive index assumptions, as well as scan direction, demonstrate modest effects on recovered properties.

Influence of supersaturated carbon on the diffusion of Ni in ferrite determined by atom probe tomography

KAUST Repository

Kresse, T.; Li, Yujiao; Boll, Torben; Borchers, Christine; Choi, Pyuckpa; Al-Kassab, Talaat; Raabe, Dierk; Kirchheim, Reiner

2013-01-01

In patented and cold-drawn pearlitic steel wires dissociation of cementite occurs during mechanical deformation. In this study the influence of the carbon decomposition on the diffusion of nickel in ferrite is investigated by means of atom probe tomography. In the temperature range 423-523 K we observed a much smaller activation energy of Ni diffusion than for self-diffusion in body-centered cubic iron, indicating an increased vacancy density owing to enhanced formation of vacancy-carbon complexes. © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Influence of supersaturated carbon on the diffusion of Ni in ferrite determined by atom probe tomography

KAUST Repository

Kresse, T.

2013-09-01

In patented and cold-drawn pearlitic steel wires dissociation of cementite occurs during mechanical deformation. In this study the influence of the carbon decomposition on the diffusion of nickel in ferrite is investigated by means of atom probe tomography. In the temperature range 423-523 K we observed a much smaller activation energy of Ni diffusion than for self-diffusion in body-centered cubic iron, indicating an increased vacancy density owing to enhanced formation of vacancy-carbon complexes. © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Phase-conjugate optical coherence tomography

International Nuclear Information System (INIS)

Erkmen, Baris I.; Shapiro, Jeffrey H.

2006-01-01

Quantum optical coherence tomography (Q-OCT) offers a factor-of-2 improvement in axial resolution and the advantage of even-order dispersion cancellation when it is compared to conventional OCT (C-OCT). These features have been ascribed to the nonclassical nature of the biphoton state employed in the former, as opposed to the classical state used in the latter. Phase-conjugate OCT (PC-OCT) shows that nonclassical light is not necessary to reap Q-OCT's advantages. PC-OCT uses classical-state signal and reference beams, which have a phase-sensitive cross correlation, together with phase conjugation to achieve the axial resolution and even-order dispersion cancellation of Q-OCT with a signal-to-noise ratio that can be comparable to that of C-OCT

Monitoring of human brain functions in risk decision-making task by diffuse optical tomography using voxel-wise general linear model

Science.gov (United States)

Lin, Zi-Jing; Li, Lin; Cazzell, Marry; Liu, Hanli

2013-03-01

Functional near-infrared spectroscopy (fNIRS) is a non-invasive imaging technique which measures the hemodynamic changes that reflect the brain activity. Diffuse optical tomography (DOT), a variant of fNIRS with multi-channel NIRS measurements, has demonstrated capability of three dimensional (3D) reconstructions of hemodynamic changes due to the brain activity. Conventional method of DOT image analysis to define the brain activation is based upon the paired t-test between two different states, such as resting-state versus task-state. However, it has limitation because the selection of activation and post-activation period is relatively subjective. General linear model (GLM) based analysis can overcome this limitation. In this study, we combine the 3D DOT image reconstruction with GLM-based analysis (i.e., voxel-wise GLM analysis) to investigate the brain activity that is associated with the risk-decision making process. Risk decision-making is an important cognitive process and thus is an essential topic in the field of neuroscience. The balloon analogue risk task (BART) is a valid experimental model and has been commonly used in behavioral measures to assess human risk taking action and tendency while facing risks. We have utilized the BART paradigm with a blocked design to investigate brain activations in the prefrontal and frontal cortical areas during decision-making. Voxel-wise GLM analysis was performed on 18human participants (10 males and 8females).In this work, we wish to demonstrate the feasibility of using voxel-wise GLM analysis to image and study cognitive functions in response to risk decision making by DOT. Results have shown significant changes in the dorsal lateral prefrontal cortex (DLPFC) during the active choice mode and a different hemodynamic pattern between genders, which are in good agreements with published literatures in functional magnetic resonance imaging (fMRI) and fNIRS studies.

Histologic correlation of in vivo optical coherence tomography images of the human retina

NARCIS (Netherlands)

Chen, T.; Cense, B.; Miller, J.S.; Rubin, P. A. D.; Deschler, D. G.; Gragoudas, E. S.; de Boer, J.F.

2006-01-01

Purpose: To correlate in vivo human retina optical coherence tomography (OCT)3 images with histology. Design: Case series. Methods: Linear OCT3 scans through the macula and optic nerve were obtained in three eyes of three patients who then underwent exenteration surgery for orbital cancers. OCT3

Evaluation of Optic Canal and Surrounding Structures Using Cone Beam Computed Tomography: Considerations for Maxillofacial Surgery.

Science.gov (United States)

Sinanoglu, Alper; Orhan, Kaan; Kursun, Sebnem; Inceoglu, Beste; Oztas, Bengi

2016-07-01

The optic canal connects the anterior cranial fossa and the orbit and maintains the optic nerve and the ophthalmic artery. Within the extent of the surgical approach of the region, risk of iatrogenic injury of the neural and vascular structures increases. The aim of this retrospective morphometric study is to investigate the radiological anatomy of orbita, optic canal, and its surrounding using cone beam computed tomography (CBCT) scans in a group of Turkish population.Cone beam computed tomography images of a total of 182 patients were evaluated by 2 observers. Anatomical parameters regarding optic canal and orbita were measured for all patients from axial, sagittal, and three-dimensional reconstructed images. To assess intraobserver reliability, the Wilcoxon matched-pairs test was used. Pearson χ test and Student t test were performed for statistical analysis of differences, sex, localization, and measurements (P  0.05). The orbita width and height were larger for the males than females (P  0.05). Examination CBCT scans revealed that the shape of the optic canal was 70% funnel and 28% Hourglass shape, 2% amorph type round.These results provide detailed knowledge of the anatomical characteristics in the orbital area which may be of assistance for surgeons preoperatively. Cone beam computed tomography scans can be an alternative modality for multislice computed tomography with submillimeter resolution and lower dose in preoperative imaging of the orbit.

Diagnostic ability of Barrett's index to detect dysthyroid optic neuropathy using multidetector computed tomography

International Nuclear Information System (INIS)

Monteiro, Mario L.R.; Goncalves, Allan C.P.; Silva, Carla T.M.; Moura, Janete P.; Ribeiro, Carolina S.; Gebrim, Eloisa M.M.S.; Universidade de Sao Paulo; Universidade de Sao Paulo

2008-01-01

Objectives: The objective of this study was to evaluate the ability of a muscular index (Barrett's Index), calculated with multidetector computed tomography, to detect dysthyroid optic neuropathy in patients with Graves' orbitopathy. Methods: Thirty-six patients with Graves' orbitopathy were prospectively studied and submitted to neuro-ophthalmic evaluation and multidetector computed tomography scans of the orbits. Orbits were divided into two groups: those with and without dysthyroid optic neuropathy. Barrett's index was calculated as the percentage of the orbit occupied by muscles. Sensitivity and specificity were determined for several index values. Results: Sixty-four orbits (19 with and 45 without dysthyroid optic neuropathy) met the inclusion criteria for the study. The mean Barrett's index values (±SD) were 64.47% ± 6.06% and 49.44% ± 10.94% in the groups with and without dysthyroid optic neuropathy, respectively (p 60% should be carefully examined and followed for the development of dysthyroid optic neuropathy. (author)

Diagnostic ability of barrett's index to detect dysthyroid optic neuropathy using multidetector computed tomography

Directory of Open Access Journals (Sweden)

Mário L. R. Monteiro

2008-01-01

Full Text Available OBJECTIVES: The objective of this study was to evaluate the ability of a muscular index (Barrett's Index, calculated with multidetector computed tomography, to detect dysthyroid optic neuropathy in patients with Graves' orbitopathy. METHODS: Thirty-six patients with Graves' orbitopathy were prospectively studied and submitted to neuro-ophthalmic evaluation and multidetector computed tomography scans of the orbits. Orbits were divided into two groups: those with and without dysthyroid optic neuropathy. Barrett's index was calculated as the percentage of the orbit occupied by muscles. Sensitivity and specificity were determined for several index values. RESULTS: Sixty-four orbits (19 with and 45 without dysthyroid optic neuropathy met the inclusion criteria for the study. The mean Barrett's index values (± SD were 64.47% ± 6.06% and 49.44% ± 10.94%in the groups with and without dysthyroid optic neuropathy, respectively (p60% should be carefully examined and followed for the development of dysthyroid optic neuropathy.

Correlation characteristics of optical coherence tomography images of turbid media with statistically inhomogeneous optical parameters

International Nuclear Information System (INIS)

Dolin, Lev S.; Sergeeva, Ekaterina A.; Turchin, Ilya V.

2012-01-01

Noisy structure of optical coherence tomography (OCT) images of turbid medium contains information about spatial variations of its optical parameters. We propose analytical model of statistical characteristics of OCT signal fluctuations from turbid medium with spatially inhomogeneous coefficients of absorption and backscattering. Analytically predicted correlation characteristics of OCT signal from spatially inhomogeneous medium are in good agreement with the results of correlation analysis of OCT images of different biological tissues. The proposed model can be efficiently applied for quantitative evaluation of statistical properties of absorption and backscattering fluctuations basing on correlation characteristics of OCT images.

Transcranial diffuse optical monitoring of microvascular cerebral hemodynamics after thrombolysis in ischemic stroke

Science.gov (United States)

Zirak, Peyman; Delgado-Mederos, Raquel; Dinia, Lavinia; Carrera, David; Martí-Fàbregas, Joan; Durduran, Turgut

2014-01-01

The ultimate goal of therapeutic strategies for ischemic stroke is to reestablish the blood flow to the ischemic region of the brain. However, currently, the local cerebral hemodynamics (microvascular) is almost entirely inaccessible for stroke clinicians at the patient bed-side, and the recanalization of the major cerebral arteries (macrovascular) is the only available measure to evaluate the therapy, which does not always reflect the local conditions. Here we report the case of an ischemic stroke patient whose microvascular cerebral blood flow and oxygenation were monitored by a compact hybrid diffuse optical monitor during thrombolytic therapy. This monitor combined diffuse correlation spectroscopy and near-infrared spectroscopy. The reperfusion assessed by hybrid diffuse optics temporally correlated with the recanalization of the middle cerebral artery (assessed by transcranial-Doppler) and was in agreement with the patient outcome. This study suggests that upon further investigation, diffuse optics might have a potential for bed-side acute stroke monitoring and therapy guidance by providing hemodynamics information at the microvascular level.

SILDENAFIL CITRATE INDUCED RETINAL TOXICITY-ELECTRORETINOGRAM, OPTICAL COHERENCE TOMOGRAPHY, AND ADAPTIVE OPTICS FINDINGS.

Science.gov (United States)

Yanoga, Fatoumata; Gentile, Ronald C; Chui, Toco Y P; Freund, K Bailey; Fell, Millie; Dolz-Marco, Rosa; Rosen, Richard B

2018-02-27

To report a case of persistent retinal toxicity associated with a high dose of sildenafil citrate intake. Single retrospective case report. A 31-year-old white man with no medical history presented with complaints of bilateral multicolored photopsias and erythropsia (red-tinted vision), shortly after taking sildenafil citrate-purchased through the internet. Patient was found to have cone photoreceptor damage, demonstrated using electroretinogram, optical coherence tomography, and adaptive optics imaging. The patient's symptoms and the photoreceptor structural changes persisted for several months. Sildenafil citrate is a widely used erectile dysfunction medication that is typically associated with transient visual symptoms in normal dosage. At high dosage, sildenafil citrate can lead to persistent retinal toxicity in certain individuals.

Photons-based medical imaging - Radiology, X-ray tomography, gamma and positrons tomography, optical imaging; Imagerie medicale a base de photons - Radiologie, tomographie X, tomographie gamma et positons, imagerie optique

Energy Technology Data Exchange (ETDEWEB)

Fanet, H.; Dinten, J.M.; Moy, J.P.; Rinkel, J. [CEA Leti, Grenoble (France); Buvat, I. [IMNC - CNRS, Orsay (France); Da Silva, A. [Institut Fresnel, Marseille (France); Douek, P.; Peyrin, F. [INSA Lyon, Lyon Univ. (France); Frija, G. [Hopital Europeen George Pompidou, Paris (France); Trebossen, R. [CEA-Service hospitalier Frederic Joliot, Orsay (France)

2010-07-01

This book describes the different principles used in medical imaging. The detection aspects, the processing electronics and algorithms are detailed for the different techniques. This first tome analyses the photons-based techniques (X-rays, gamma rays and visible light). Content: 1 - physical background: radiation-matter interaction, consequences on detection and medical imaging; 2 - detectors for medical imaging; 3 - processing of numerical radiography images for quantization; 4 - X-ray tomography; 5 - positrons emission tomography: principles and applications; 6 - mono-photonic imaging; 7 - optical imaging; Index. (J.S.)

Gabor fusion master slave optical coherence tomography

DEFF Research Database (Denmark)

Cernat, Ramona; Bradu, Adrian; Israelsen, Niels Møller

2017-01-01

This paper describes the application of the Gabor filtering protocol to a Master/Slave (MS) swept source optical coherence tomography (SS)-OCT system at 1300 nm. The MS-OCT system delivers information from selected depths, a property that allows operation similar to that of a time domain OCT system......, where dynamic focusing is possible. The Gabor filtering processing following collection of multiple data from different focus positions is different from that utilized by a conventional swept source OCT system using a Fast Fourier transform (FFT) to produce an A-scan. Instead of selecting the bright...

Visible-light optical coherence tomography: a review

Science.gov (United States)

Shu, Xiao; Beckmann, Lisa; Zhang, Hao F.

2017-12-01

Visible-light optical coherence tomography (vis-OCT) is an emerging imaging modality, providing new capabilities in both anatomical and functional imaging of biological tissue. It relies on visible light illumination, whereas most commercial and investigational OCTs use near-infrared light. As a result, vis-OCT requires different considerations in engineering design and implementation but brings unique potential benefits to both fundamental research and clinical care of several diseases. Here, we intend to provide a summary of the development of vis-OCT and its demonstrated applications. We also provide perspectives on future technology improvement and applications.

Near-infrared optical coherence tomography for the inspection of fiber composites

NARCIS (Netherlands)

Liu, P.; Yao, L.; Groves, R.M.

2015-01-01

Optical coherence tomography (OCT) is a non-invasive imaging method, which allows the econstruction of three dimensional depth-resolved images with microscale resolution. Originally developed for biomedical diagnostics, nowadays it also shows a high potential for applications in the field of

Measurement of biofilm growth and local hydrodynamics using optical coherence tomography

NARCIS (Netherlands)

Weiss, Nicolas; El Tayeb El Obied, Khalid; Kalkman, Jeroen; Lammertink, Rob G.H.; van Leeuwen, Ton G.

2016-01-01

We report on localized and simultaneous measurement of biofilm growth and local hydrodynamics in a microfluidic channel using optical coherence tomography. We measure independently with high spatio-temporal resolution the longitudinal flow velocity component parallel to the imaging beam and the

Novelty detection-based internal fingerprint segmentation in optical coherence tomography images

CSIR Research Space (South Africa)

Khutlang, R

2014-12-01

Full Text Available present an automatic segmentation of the papillary layer method, in 3-D swept source optical coherence tomography (SS-OCT) images. The papillary contour represents the internal fingerprint, which does not suffer external skin problems. The slices composing...

Novelty detection-based internal fingerprint segmentation in optical coherence tomography images

CSIR Research Space (South Africa)

Khutlang, Rethabile

2017-08-01

Full Text Available present an automatic segmentation of the papillary layer method, from images acquired using contact-less 3-D swept source optical coherence tomography (OCT). The papillary contour represents the internal fingerprint, which does not suffer from the external...

Influence of diffuse reflectance measurement accuracy on the scattering coefficient in determination of optical properties with integrating sphere optics (a secondary publication).

Science.gov (United States)

Horibe, Takuro; Ishii, Katsunori; Fukutomi, Daichi; Awazu, Kunio

2015-12-30

An estimation error of the scattering coefficient of hemoglobin in the high absorption wavelength range has been observed in optical property calculations of blood-rich tissues. In this study, the relationship between the accuracy of diffuse reflectance measurement in the integrating sphere and calculated scattering coefficient was evaluated with a system to calculate optical properties combined with an integrating sphere setup and the inverse Monte Carlo simulation. Diffuse reflectance was measured with the integrating sphere using a small incident port diameter and optical properties were calculated. As a result, the estimation error of the scattering coefficient was improved by accurate measurement of diffuse reflectance. In the high absorption wavelength range, the accuracy of diffuse reflectance measurement has an effect on the calculated scattering coefficient.

The influence of glass fibers on elongational viscosity studied by means of optical coherence tomography and X-ray computed tomography

International Nuclear Information System (INIS)

Aigner, M.; Köpplmayr, T.; Lang, C.; Burzic, I.; Miethlinger, J.; Salaberger, D.; Buchsbaum, A.; Leitner, M.; Heise, B.; Schausberger, S. E.; Stifter, D.

2014-01-01

We report on the flow characteristics of glass-fiber-reinforced polymers in elongational rheometry. Unlike polymers with geometrically isotropic fillers, glass-fiber-reinforced polymers exhibit flow behavior and rheology that depend heavily on the orientation, the length distribution and the content of the fibers. One of the primary objectives of this study was to determine the effect of fiber orientation, concentration and distribution on the entrance pressure drop by means of optical coherence tomography (OCT), full-field optical coherence microscopy (FF-OCM), and X-ray computed tomography (X-CT). Both pressure drop and melt flow were analyzed using a special elongation die (Thermo Scientific X-Die [3]) for inline measurements. Samples with a variety of fiber volume fractions, fiber lengths and processing temperatures were measured

The influence of glass fibers on elongational viscosity studied by means of optical coherence tomography and X-ray computed tomography

Science.gov (United States)

Aigner, M.; Salaberger, D.; Buchsbaum, A.; Heise, B.; Schausberger, S. E.; Köpplmayr, T.; Lang, C.; Leitner, M.; Stifter, D.; Burzic, I.; Miethlinger, J.

2014-05-01

We report on the flow characteristics of glass-fiber-reinforced polymers in elongational rheometry. Unlike polymers with geometrically isotropic fillers, glass-fiber-reinforced polymers exhibit flow behavior and rheology that depend heavily on the orientation, the length distribution and the content of the fibers. One of the primary objectives of this study was to determine the effect of fiber orientation, concentration and distribution on the entrance pressure drop by means of optical coherence tomography (OCT), full-field optical coherence microscopy (FF-OCM), and X-ray computed tomography (X-CT). Both pressure drop and melt flow were analyzed using a special elongation die (Thermo Scientific X-Die [3]) for inline measurements. Samples with a variety of fiber volume fractions, fiber lengths and processing temperatures were measured.

The effects of internal refractive index variation in near-infrared optical tomography: a finite element modelling approach

International Nuclear Information System (INIS)

Dehghani, Hamid; Brooksby, Ben; Vishwanath, Karthik; Pogue, Brian W; Paulsen, Keith D

2003-01-01

Near-infrared (NIR) tomography is a technique used to measure light propagation through tissue and generate images of internal optical property distributions from boundary measurements. Most popular applications have concentrated on female breast imaging, neonatal and adult head imaging, as well as muscle and small animal studies. In most instances a highly scattering medium with a homogeneous refractive index is assumed throughout the imaging domain. Using these assumptions, it is possible to simplify the model to the diffusion approximation. However, biological tissue contains regions of varying optical absorption and scatter, as well as varying refractive index. In this work, we introduce an internal boundary constraint in the finite element method approach to modelling light propagation through tissue that accounts for regions of different refractive indices. We have compared the results to data from a Monte Carlo simulation and show that for a simple two-layered slab model of varying refractive index, the phase of the measured reflectance data is significantly altered by the variation in internal refractive index, whereas the amplitude data are affected only slightly

Resonant acoustic spectroscopy of soft tissues using embedded magnetomotive nanotransducers and optical coherence tomography

International Nuclear Information System (INIS)

Oldenburg, Amy L; Boppart, Stephen A

2010-01-01

We present a new method for performing dynamic elastography of soft tissue samples. By sensing nanoscale displacements with optical coherence tomography, a chirped, modulated force is applied to acquire the mechanical spectrum of a tissue sample within a few seconds. This modulated force is applied via magnetic nanoparticles, named 'nanotransducers', which are diffused into the tissue, and which contribute negligible inertia to the soft tissue mechanical system. Using this novel system, we observed that excised tissues exhibit mechanical resonance modes which are well described by a linear damped harmonic oscillator. Results are validated by using cylindrical tissue phantoms of agarose in which resonant frequencies (30-400 Hz) are consistent with longitudinal modes and the sample boundary conditions. We furthermore show that the Young's modulus can be computed from their measured resonance frequencies, analogous to resonant ultrasound spectroscopy for stiff material analysis. Using this new technique, named magnetomotive resonant acoustic spectroscopy (MRAS), we monitored the relative stiffening of an excised rat liver during a chemical fixation process.

Measuring optical properties of a blood vessel model using optical coherence tomography

Science.gov (United States)

Levitz, David; Hinds, Monica T.; Tran, Noi; Vartanian, Keri; Hanson, Stephen R.; Jacques, Steven L.

2006-02-01

In this paper we develop the concept of a tissue-engineered optical phantom that uses engineered tissue as a phantom for calibration and optimization of biomedical optics instrumentation. With this method, the effects of biological processes on measured signals can be studied in a well controlled manner. To demonstrate this concept, we attempted to investigate how the cellular remodeling of a collagen matrix affected the optical properties extracted from optical coherence tomography (OCT) images of the samples. Tissue-engineered optical phantoms of the vascular system were created by seeding smooth muscle cells in a collagen matrix. Four different optical properties were evaluated by fitting the OCT signal to 2 different models: the sample reflectivity ρ and attenuation parameter μ were extracted from the single scattering model, and the scattering coefficient μ s and root-mean-square scattering angle θ rms were extracted from the extended Huygens-Fresnel model. We found that while contraction of the smooth muscle cells was clearly evident macroscopically, on the microscopic scale very few cells were actually embedded in the collagen. Consequently, no significant difference between the cellular and acellular samples in either set of measured optical properties was observed. We believe that further optimization of our tissue-engineering methods is needed in order to make the histology and biochemistry of the cellular samples sufficiently different from the acellular samples on the microscopic level. Once these methods are optimized, we can better verify whether the optical properties of the cellular and acellular collagen samples differ.

Optical coherence tomography in dermatology

Science.gov (United States)

Sattler, Elke; Kästle, Raphaela; Welzel, Julia

2013-06-01

Optical coherence tomography (OCT) is a noninvasive diagnostic method that offers a view into the superficial layers of the skin in vivo in real-time. An infrared broadband light source allows the investigation of skin architecture and changes up to a depth of 1 to 2 mm with a resolution between 15 and 3 μm, depending on the system used. Thus OCT enables evaluation of skin lesions, especially nonmelanoma skin cancers and inflammatory diseases, quantification of skin changes, visualization of parasitic infestations, and examination of other indications such as the investigation of nails. OCT provides a quick and useful diagnostic imaging technique for a number of clinical questions and is a valuable addition or complement to other noninvasive imaging tools such as dermoscopy, high-frequency ultrasound, and confocal laser scan microscopy.

Optic disc size and other parameters from optical coherence tomography in Vietnamese-Americans.

Science.gov (United States)

Peng, Pai-Huei; Fu, Sheena; Nguyen, Ngoc; Porco, Travis; Lin, Shan C

2011-08-01

To investigate the optic disc parameters by optical coherence tomography (OCT) in Vietnamese with various types of glaucoma. Medical charts of Vietnamese and White patients within a single practice were reviewed. Disc and rim areas by OCT were compared among nonglaucoma controls, different types of glaucoma, and glaucoma suspect. The association of these parameters with demographic and ocular features was evaluated. Data from 1416 Vietnamese and 57 White patients were included. A larger mean disc area was observed in eyes with primary angle-closure glaucoma than in eyes with primary angle-closure and primary angle-closure suspect (both PVietnamese patients with glaucoma and glaucoma suspicion had larger discs than diagnosis-matched Whites (P=0.043 and 0.021, respectively). Vietnamese patients with glaucoma seem to have larger optic discs than White patients. Central corneal thickness had no association with disc area in this study population.

Optical coherence tomography: Monte Carlo simulation and improvement by optical amplification

DEFF Research Database (Denmark)

Tycho, Andreas

2002-01-01

An advanced novel Monte Carlo simulation model of the detection process of an optical coherence tomography (OCT) system is presented. For the first time it is shown analytically that the applicability of the incoherent Monte Carlo approach to model the heterodyne detection process of an OCT system...... is firmly justified. This is obtained by calculating the heterodyne mixing of the reference and sample beams in a plane conjugate to the discontinuity in the sample probed by the system. Using this approach, a novel expression for the OCT signal is derived, which only depends uopon the intensity...... flexibility of Monte Carlo simulations, this new model is demonstrated to be excellent as a numerical phantom, i.e., as a substitute for otherwise difficult experiments. Finally, a new model of the signal-to-noise ratio (SNR) of an OCT system with optical amplification of the light reflected from the sample...

Optical Coherence Tomography-Guided Decisions in Retinoblastoma Management.

Science.gov (United States)

Soliman, Sameh E; VandenHoven, Cynthia; MacKeen, Leslie D; Héon, Elise; Gallie, Brenda L

2017-06-01

Assess the role of handheld optical coherence tomography (OCT) in guiding management decisions during diagnosis, treatment, and follow-up of eyes affected by retinoblastoma. Retrospective, noncomparative, single-institution case series. All children newly diagnosed with retinoblastoma from January 2011 to December 2015 who had an OCT session during their active treatment at The Hospital for Sick Children (SickKids) in Toronto, Canada. The OCT sessions for fellow eyes of unilateral retinoblastoma without any suspicious lesion and those performed more than 6 months after the last treatment were excluded. Data collected included age at presentation, sex, family history, RB1 mutation status, 8th edition TNMH cancer staging and International Intraocular Retinoblastoma Classification (IIRC), and number of OCT sessions per eye. Details of each session were scored for indication-related details (informative or not) and assessed for guidance (directive or not), diagnosis (staging changed, new tumors found or excluded), treatment (modified, stopped, or modality shifted), or follow-up modified. Frequency of OCT-guided management decisions, stratified by indication and type of guidance (confirmatory vs. influential). Sixty-three eyes of 44 children had 339 OCT sessions over the course of clinical management (median number of OCT scans per eye, 5; range, 1-15). The age at presentation and presence of a heritable RB1 mutation significantly correlated with an increased number of OCT sessions. Indications included evaluation of post-treatment scar (55%) or fovea (16%), and posterior pole scanning for new tumors (11%). Of all sessions, 92% (312/339) were informative; 19 of 27 noninformative sessions had large, elevated lesions; of these, 14 of 19 were T2a or T2b (IIRC group C or D) eyes. In 94% (293/312) of the informative sessions, OCT directed treatment decisions (58%), diagnosis (16%), and follow-up (26%). Optical coherence tomography influenced and changed management from pre

Optical coherence tomography of the preterm eye: from retinopathy of prematurity to brain development

Science.gov (United States)

Rothman, Adam L; Mangalesh, Shwetha; Chen, Xi; Toth, Cynthia A

2016-01-01

Preterm infants with retinopathy of prematurity are at increased risk of poor neurodevelopmental outcomes. Because the neurosensory retina is an extension of the central nervous system, anatomic abnormalities in the anterior visual pathway often relate to system and central nervous system health. We describe optical coherence tomography as a powerful imaging modality that has recently been adapted to the infant population and provides noninvasive, high-resolution, cross-sectional imaging of the infant eye at the bedside. Optical coherence tomography has increased understanding of normal eye development and has identified several potential biomarkers of brain abnormalities and poorer neurodevelopment. PMID:28539807

Performance Enhancement of Pharmacokinetic Diffuse Fluorescence Tomography by Use of Adaptive Extended Kalman Filtering.

Science.gov (United States)

Wang, Xin; Wu, Linhui; Yi, Xi; Zhang, Yanqi; Zhang, Limin; Zhao, Huijuan; Gao, Feng

2015-01-01

Due to both the physiological and morphological differences in the vascularization between healthy and diseased tissues, pharmacokinetic diffuse fluorescence tomography (DFT) can provide contrast-enhanced and comprehensive information for tumor diagnosis and staging. In this regime, the extended Kalman filtering (EKF) based method shows numerous advantages including accurate modeling, online estimation of multiparameters, and universal applicability to any optical fluorophore. Nevertheless the performance of the conventional EKF highly hinges on the exact and inaccessible prior knowledge about the initial values. To address the above issues, an adaptive-EKF scheme is proposed based on a two-compartmental model for the enhancement, which utilizes a variable forgetting-factor to compensate the inaccuracy of the initial states and emphasize the effect of the current data. It is demonstrated using two-dimensional simulative investigations on a circular domain that the proposed adaptive-EKF can obtain preferable estimation of the pharmacokinetic-rates to the conventional-EKF and the enhanced-EKF in terms of quantitativeness, noise robustness, and initialization independence. Further three-dimensional numerical experiments on a digital mouse model validate the efficacy of the method as applied in realistic biological systems.

Spectral shaping for non-Gaussian source spectra in optical coherence tomography

NARCIS (Netherlands)

Tripathi, R; Nassif, N. A.; Nelson, JS; Park, B.H.; de Boer, JF

2002-01-01

We present a digital spectral shaping technique to reduce the sidelobes (ringing) of the axial point-spread function in optical coherence tomography for non-Gaussian-shaped source spectra. The spectra of two superluminescent diodes were combined to generate a spectrum with significant modulation.

Scanning, non-contact, hybrid broadband diffuse optical spectroscopy and diffuse correlation spectroscopy system.

Science.gov (United States)

Johansson, Johannes D; Mireles, Miguel; Morales-Dalmau, Jordi; Farzam, Parisa; Martínez-Lozano, Mar; Casanovas, Oriol; Durduran, Turgut

2016-02-01

A scanning system for small animal imaging using non-contact, hybrid broadband diffuse optical spectroscopy (ncDOS) and diffuse correlation spectroscopy (ncDCS) is presented. The ncDOS uses a two-dimensional spectrophotometer retrieving broadband (610-900 nm) spectral information from up to fifty-seven source-detector distances between 2 and 5 mm. The ncDCS data is simultaneously acquired from four source-detector pairs. The sample is scanned in two dimensions while tracking variations in height. The system has been validated with liquid phantoms, demonstrated in vivo on a human fingertip during an arm cuff occlusion and on a group of mice with xenoimplanted renal cell carcinoma.

Optical coherence tomography as an accurate inspection and quality evaluation technique in paper industry

Science.gov (United States)

Prykäri, Tuukka; Czajkowski, Jakub; Alarousu, Erkki; Myllylä, Risto

2010-05-01

Optical coherence tomography (OCT), a technique for the noninvasive imaging of turbid media, based on low-coherence interferometry, was originally developed for the imaging of biological tissues. Since the development of the technique, most of its applications have been related to the area of biomedicine. However, from early stages, the vertical resolution of the technique has already been improved to a submicron scale. This enables new possibilities and applications. This article presents the possible applications of OCT in paper industry, where submicron or at least a resolution close to one micron is required. This requirement comes from the layered structure of paper products, where layer thickness may vary from single microns to tens of micrometers. This is especially similar to the case with high-quality paper products, where several different coating layers are used to obtain a smooth surface structure and a high gloss. In this study, we demonstrate that optical coherence tomography can be used to measure and evaluate the quality of the coating layer of a premium glossy photopaper. In addition, we show that for some paper products, it is possible to measure across the entire thickness range of a paper sheet. Furthermore, we suggest that in addition to topography and tomography images of objects, it is possible to obtain information similar to gloss by tracking the magnitude of individual interference signals in optical coherence tomography.

Time domain diffuse optical spectroscopy: In vivo quantification of collagen in breast tissue

Science.gov (United States)

Taroni, Paola; Pifferi, Antonio; Quarto, Giovanna; Farina, Andrea; Ieva, Francesca; Paganoni, Anna Maria; Abbate, Francesca; Cassano, Enrico; Cubeddu, Rinaldo

2015-05-01

Time-resolved diffuse optical spectroscopy provides non-invasively the optical characterization of highly diffusive media, such as biological tissues. Light pulses are injected into the tissue and the effects of light propagation on re-emitted pulses are interpreted with the diffusion theory to assess simultaneously tissue absorption and reduced scattering coefficients. Performing spectral measurements, information on tissue composition and structure is derived applying the Beer law to the measured absorption and an empiric approximation to Mie theory to the reduced scattering. The absorption properties of collagen powder were preliminarily measured in the range of 600-1100 nm using a laboratory set-up for broadband time-resolved diffuse optical spectroscopy. Optical projection images were subsequently acquired in compressed breast geometry on 218 subjects, either healthy or bearing breast lesions, using a portable instrument for optical mammography that operates at 7 wavelengths selected in the range 635-1060 nm. For all subjects, tissue composition was estimated in terms of oxy- and deoxy-hemoglobin, water, lipids, and collagen. Information on tissue microscopic structure was also derived. Good correlation was obtained between mammographic breast density (a strong risk factor for breast cancer) and an optical index based on collagen content and scattering power (that accounts mostly for tissue collagen). Logistic regression applied to all optically derived parameters showed that subjects at high risk for developing breast cancer for their high breast density can effectively be identified based on collagen content and scattering parameters. Tissue composition assessed in breast lesions with a perturbative approach indicated that collagen and hemoglobin content are significantly higher in malignant lesions than in benign ones.

Simultaneous characterization of rotational and translational diffusion of optically anisotropic particles by optical microscopy

International Nuclear Information System (INIS)

Giavazzi, Fabio; Cerbino, Roberto; Haro-Pérez, Catalina

2016-01-01

We probe the roto-translational Brownian motion of optically anisotropic particles suspended in water with a simple and straightforward optical microscopy experiment that does not require positional or rotational particle tracking. We acquire a movie of the suspension placed between two polarizing elements and we extract the translational diffusion coefficient D T and the rotational diffusion coefficient D R from the analysis of the temporal correlation properties of the spatial Fourier modes of the intensity fluctuations in the movie. Our method is successfully tested with a dilute suspension of birefringent spherical colloidal particles obtained by polymerizing an emulsion of droplets of liquid crystal in a nematic phase, whose roto-translational dynamics is found to be well described by theory. The simplicity of our approach makes our method a viable alternative to particle tracking and depolarized dynamic light scattering. (paper)

A fast and high-sensitive dual-wavelength diffuse optical tomography system using digital lock-in photon-counting technique

Science.gov (United States)

Chen, Weiting; Yi, Xi; Zhao, Huijuan; Gao, Feng

2014-09-01

We presented a novel dual-wavelength diffuse optical imaging system which can perform 2-D or 3-D imaging fast and high-sensitively for monitoring the dynamic change of optical parameters. A newly proposed lock-in photon-counting detection method was adopted for week optical signal collection, which brought in excellent property as well as simplified geometry. Fundamental principles of the lock-in photon-counting detection were elaborately demonstrated, and the feasibility was strictly verified by the linearity experiment. Systemic performance of the prototype set up was experimentally accessed, including stray light rejection and inherent interference. Results showed that the system possessed superior anti-interference capability (under 0.58% in darkroom) compared with traditional photon-counting detection, and the crosstalk between two wavelengths was lower than 2.28%. For comprehensive assessment, 2-D phantom experiments towards relatively large dimension model (diameter of 4cm) were conducted. Different absorption targets were imaged to investigate detection sensitivity. Reconstruction image under all conditions was exciting, with a desirable SNR. Study on image quality v.s. integration time put forward a new method for accessing higher SNR with the sacrifice of measuring speed. In summary, the newly developed system showed great potential in promoting detection sensitivity as well as measuring speed. This will make substantial progress in dynamically tracking the blood concentration distribution in many clinical areas, such as small animal disease modeling, human brain activity research and thick tissues (for example, breast) diagnosis.

The tomography inside of a Fourier Optics course: some opto-mechanical illustrative arrays

International Nuclear Information System (INIS)

Rodriguez Z, G.; Rodriguez V, R.; Luna C, A.

1999-01-01

The introduction of tomography as an advanced topic to be included in a Fourier optics course at graduated level is proposed. It is shown a possible presentation sequence which features the use of typical Fourier optics techniques, as well as some well known opto-mechanical devices as examples. Finally, a simplified apparatus which illustrates the central Fourier theorem as an experimental project on Fourier optics is described. Corresponding experimental results are also shown. (Author)

Optical coherence tomography: a potential tool to predict premature rupture of fetal membranes.

Science.gov (United States)

Micili, Serap C; Valter, Markus; Oflaz, Hakan; Ozogul, Candan; Linder, Peter; Föckler, Nicole; Artmann, Gerhard M; Digel, Ilya; Artmann, Aysegul T

2013-04-01

A fundamental question addressed in this study was the feasibility of preterm birth prediction based on a noncontact investigation of fetal membranes in situ. Although the phenomena of preterm birth and the premature rupture of the fetal membrane are well known, currently, there are no diagnostic tools for their prediction. The aim of this study was to assess whether optical coherence tomography could be used for clinical investigations of high-risk pregnancies. The thickness of fetal membranes was measured in parallel by optical coherence tomography and histological techniques for the following types of birth: normal births, preterm births without premature ruptures and births at full term with premature rupture of membrane. Our study revealed that the membrane thickness correlates with the birth type. Normal births membranes were statistically significantly thicker than those belonging to the other two groups. Thus, in spite of almost equal duration of gestation of the normal births and the births at full term with premature rupture, the corresponding membrane thicknesses differed. This difference is possibly related to previously reported water accumulation in the membranes. The optical coherence tomography results were encouraging, suggesting that this technology could be used in future to predict and distinguish between different kinds of births.

In vivo assessment of optical properties of basal cell carcinoma and differentiation of BCC subtypes by high-definition optical coherence tomography

DEFF Research Database (Denmark)

Boone, Marc; Suppa, Mariano; Miyamoto, Makiko

2016-01-01

High-definition optical coherence tomography (HD-OCT) features of basal cell carcinoma (BCC) have recently been defined. We assessed in vivo optical properties (IV-OP) of BCC, by HD-OCT. Moreover their critical values for BCC subtype differentiation were determined. The technique of semi-log plot...

Miniaturized pulsed laser source for time-domain diffuse optics routes to wearable devices.

Science.gov (United States)

Di Sieno, Laura; Nissinen, Jan; Hallman, Lauri; Martinenghi, Edoardo; Contini, Davide; Pifferi, Antonio; Kostamovaara, Juha; Mora, Alberto Dalla

2017-08-01

We validate a miniaturized pulsed laser source for use in time-domain (TD) diffuse optics, following rigorous and shared protocols for performance assessment of this class of devices. This compact source (12×6  mm2) has been previously developed for range finding applications and is able to provide short, high energy (∼100  ps, ∼0.5  nJ) optical pulses at up to 1 MHz repetition rate. Here, we start with a basic level laser characterization with an analysis of suitability of this laser for the diffuse optics application. Then, we present a TD optical system using this source and its performances in both recovering optical properties of tissue-mimicking homogeneous phantoms and in detecting localized absorption perturbations. Finally, as a proof of concept of in vivo application, we demonstrate that the system is able to detect hemodynamic changes occurring in the arm of healthy volunteers during a venous occlusion. Squeezing the laser source in a small footprint removes a key technological bottleneck that has hampered so far the realization of a miniaturized TD diffuse optics system, able to compete with already assessed continuous-wave devices in terms of size and cost, but with wider performance potentialities, as demonstrated by research over the last two decades. (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

Quantifying Optical Microangiography Images Obtained from a Spectral Domain Optical Coherence Tomography System

Directory of Open Access Journals (Sweden)

Roberto Reif

2012-01-01

Full Text Available The blood vessel morphology is known to correlate with several diseases, such as cancer, and is important for describing several tissue physiological processes, like angiogenesis. Therefore, a quantitative method for characterizing the angiography obtained from medical images would have several clinical applications. Optical microangiography (OMAG is a method for obtaining three-dimensional images of blood vessels within a volume of tissue. In this study we propose to quantify OMAG images obtained with a spectral domain optical coherence tomography system. A technique for determining three measureable parameters (the fractal dimension, the vessel length fraction, and the vessel area density is proposed and validated. Finally, the repeatability for acquiring OMAG images is determined, and a new method for analyzing small areas from these images is proposed.

Method of optical coherence tomography with parallel depth-resolved signal reception and fibre-optic phase modulators

Energy Technology Data Exchange (ETDEWEB)

Morozov, A N; Turchin, I V [Institute of Applied Physics, Russian Academy of Sciences, Nizhnii Novgorod (Russian Federation)

2013-12-31

The method of optical coherence tomography with the scheme of parallel reception of the interference signal (P-OCT) is developed on the basis of spatial paralleling of the reference wave by means of a phase diffraction grating producing the appropriate time delay in the Mach–Zehnder interferometer. The absence of mechanical variation of the optical path difference in the interferometer essentially reduces the time required for 2D imaging of the object internal structure, as compared to the classical OCT that uses the time-domain method of the image construction, the sensitivity and the dynamic range being comparable in both approaches. For the resulting field of the interfering object and reference waves an analytical expression is derived that allows the calculation of the autocorrelation function in the plane of photodetectors. For the first time a method of linear phase modulation by 2π is proposed for P-OCT systems, which allows the use of compact high-frequency (a few hundred kHz) piezoelectric cell-based modulators. For the demonstration of the P-OCT method an experimental setup was created, using which the images of the inner structure of biological objects at the depth up to 1 mm with the axial spatial resolution of 12 μm were obtained. (optical coherence tomography)

All fiber optics circular-state swept source polarization-sensitive optical coherence tomography.

Science.gov (United States)

Lin, Hermann; Kao, Meng-Chun; Lai, Chih-Ming; Huang, Jyun-Cin; Kuo, Wen-Chuan

2014-02-01

A swept source (SS)-based circular-state (CS) polarization-sensitive optical coherence tomography (PS-OCT) constructed entirely with polarization-maintaining fiber optics components is proposed with the experimental verification. By means of the proposed calibration scheme, bulk quarter-wave plates can be replaced by fiber optics polarization controllers to, therefore, realize an all-fiber optics CS SSPS-OCT. We also present a numerical dispersion compensation method, which can not only enhance the axial resolution, but also improve the signal-to-noise ratio of the images. We demonstrate that this compact and portable CS SSPS-OCT system with an accuracy comparable to bulk optics systems requires less stringent lens alignment and can possibly serve as a technology to realize PS-OCT instrument for clinical applications (e.g., endoscopy). The largest deviations in the phase retardation (PR) and fast-axis (FA) angle due to sample probe in the linear scanning and a rotation angle smaller than 65 deg were of the same order as those in stationary probe setups. The influence of fiber bending on the measured PR and FA is also investigated. The largest deviations of the PR were 3.5 deg and the measured FA change by ~12 to 21 deg. Finally, in vivo imaging of the human fingertip and nail was successfully demonstrated with a linear scanning probe.

Alterations of the outer retina in non-arteritic anterior ischaemic optic neuropathy detected using spectral-domain optical coherence tomography.

Science.gov (United States)

Ackermann, Philipp; Brachert, Maike; Albrecht, Philipp; Ringelstein, Marius; Finis, David; Geerling, Gerd; Aktas, Orhan; Guthoff, Rainer

2017-07-01

A characteristic disease pattern may be reflected by retinal layer thickness changes in non-arteritic anterior ischaemic optic neuropathy measured using spectraldomain optical coherence tomography. Retinal layer segmentation is enabled by advanced software. In this study, retinal layer thicknesses in acute and chronic non-arteritic anterior ischaemic optic neuropathy were compared. A single-centre cross-sectional analysis was used. A total of 27 patients (20 age-matched healthy eyes) were included: 14 with acute (optic neuropathy. Macular volume and 12° peripapillary ring optical coherence tomography scans were used. The peripapillary thicknesses of the following layers were determined by manual segmentation: retinal nerve fibres, ganglion cells + inner plexiform layer, inner nuclear layer + outer plexiform layer, outer nuclear layer + inner segments of the photoreceptors and outer segments of the photoreceptors to Bruch's membrane. Macular retinal layer thicknesses were automatically determined in volume cubes centred on the fovea. Peripapillary retinal swelling in acute nonarteritic anterior ischaemic optic neuropathy was attributable to retinal nerve fibre layer, ganglion cell layer/inner plexiform layer and outer nuclear layer/segments of the photoreceptors thickening. In chronic cases, peripapillary retinal nerve fibre layer, macular ganglion cell layer and inner plexiform layer thinning were observed. In acute non-arteritic anterior ischaemic optic neuropathy, the inner and outer peripapillary retinal layers are affected by thickness changes. In chronic cases, atrophy of the ganglion cells and their axons and dendrites is evident by inner retinal layer thinning. © 2017 Royal Australian and New Zealand College of Ophthalmologists.

Consensus standards for acquisition, measurement, and reporting of intravascular optical coherence tomography studies: a report from the International Working Group for Intravascular Optical Coherence Tomography Standardization and Validation

DEFF Research Database (Denmark)

Falk, Erling

2012-01-01

The purpose of this document is to make the output of the International Working Group for Intravascular Optical Coherence Tomography (IWG-IVOCT) Standardization and Validation available to medical and scientific communities, through a peer-reviewed publication, in the interest of improving...

Consensus standards for acquisition, measurement, and reporting of intravascular optical coherence tomography studies : A report from the International Working Group for Intravascular Optical Coherence Tomography Standardization and Validation

NARCIS (Netherlands)

G.J. Tearney (Guillermo); E.S. Regar (Eveline); T. Akasaka (Takashi); S. Adriaenssens (Stef); P. Barlis (Peter); H.G. Bezerra (Hiram); B.E. Bouma (Brett); N. Bruining (Nico); J.-M. Cho (Jin-Man); S. Chowdhary (Saqib); M.A. Costa (Marco); R. de Silva (Ranil); J. Dijkstra (Jouke); C. di Mario (Carlo); D. Dudeck (Darius); E. Falk (Erling); M.D. Feldman (Marc); P.J. Fitzgerald (Peter); H.M. Garcia-Garcia (Hector); N. Gonzalo (Nieves); J.F. Granada (Juan); G. Guagliumi (Giulio); N.R. Holm (Niels); Y. Honda (Yasuhiro); F. Ikeno (Fumiaki); Y. Kawasaki; W. Kochman (Waclav); L. Koltowski (Lukasz); T. Kubo (Takashi); T. Kume (Teruyoshi); H. Kyono (Hiroyuki); C.C.S. Lam (Cheung Chi Simon); G. Lamouche (Guy); D.P. Lee (David); M.B. Leon (Martin); A. Maehara (Akiko); O. Manfrini (Olivia); G.S. Mintz (Gary); K. Mizuno (Kyiouchi); M-A.M. Morel (Marie-Angèle); S. Nadkarni (Seemantini); H. Okura (Hiroyuki); H. Otake (Hiromasa); A. Pietrasik (Arkadiusz); F. Prati (Francesco); L. Rber (Lorenz); M. Radu (Maria); N. Rieber (Nikolaus); M. Riga (Maria); S.M. Rollins; M. Rosenberg (Mireille); V. Sirbu (Vasile); P.W.J.C. Serruys (Patrick); K. Shimada; T. Shinke (Toshiro); J. Shite (Junya); E. Siegel (Eliot); S. Sonada (Shinjo); U. Suter (Ueli); S. Takarada (Shigeho); A. Tanaka (Atsushi); M. Terashima (Mitsuyasu); T. Troels (Thim); M. Uemura (Mayu); G.J. Ughi (Giovanni); H.M.M. van Beusekom (Heleen); A.F.W. van der Steen (Ton); G.A. van Es (Gerrit Anne); G. van Soest (Gijs); R. Virmani (Renu); S. Waxman (Sergio); N.J. Weissman (Neil); G. Weisz (Giora)

2012-01-01

textabstractObjectives: The purpose of this document is to make the output of the International Working Group for Intravascular Optical Coherence Tomography (IWG-IVOCT) Standardization and Validation available to medical and scientific communities, through a peer-reviewed publication, in the

Optical coherence tomography a clinical and technical update

CERN Document Server

Cunha-Vaz, José

2012-01-01

Optical Coherence Tomography represents the ultimate noninvasive  ocular imaging technique although being in the field for over two-decades. This book encompasses both medical and technical developments and recent achievements. Here, the authors cover the field of application from the anterior to the posterior ocular segments (Part I) and present a comprehensive review on the development of OCT. Important developments towards  clinical applications are covered in Part II, ranging from the adaptive optics to the integration on a slit-lamp, and passing through new structural  and functional information extraction from OCT data. The book is intended to be informative, coherent and comprehensive for both the medical and technical communities and aims at easing the communication between the two fields and bridging the gap between the two scientific communities.

Diffusion-sensitive optical coherence tomography for real-time monitoring of mucus thinning treatments

Science.gov (United States)

Blackmon, Richard L.; Kreda, Silvia M.; Sears, Patrick R.; Ostrowski, Lawrence E.; Hill, David B.; Chapman, Brian S.; Tracy, Joseph B.; Oldenburg, Amy L.

2016-03-01

Mucus hydration (wt%) has become an increasingly useful metric in real-time assessment of respiratory health in diseases like cystic fibrosis and COPD, with higher wt% indicative of diseased states. However, available in vivo rheological techniques are lacking. Gold nanorods (GNRs) are attractive biological probes whose diffusion through tissue is sensitive to the correlation length of comprising biopolymers. Through employment of dynamic light scattering theory on OCT signals from GNRs, we find that weakly-constrained GNR diffusion predictably decreases with increasing wt% (more disease-like) mucus. Previously, we determined this method is robust against mucus transport on human bronchial epithelial (hBE) air-liquid interface cultures (R2=0.976). Here we introduce diffusion-sensitive OCT (DS-OCT), where we collect M-mode image ensembles, from which we derive depth- and temporally-resolved GNR diffusion rates. DS-OCT allows for real-time monitoring of changing GNR diffusion as a result of topically applied mucus-thinning agents, enabling monitoring of the dynamics of mucus hydration never before seen. Cultured human airway epithelial cells (Calu-3 cell) with a layer of endogenous mucus were doped with topically deposited GNRs (80x22nm), and subsequently treated with hypertonic saline (HS) or isotonic saline (IS). DS-OCT provided imaging of the mucus thinning response up to a depth of 600μm with 4.65μm resolution, over a total of 8 minutes in increments of >=3 seconds. For both IS and HS conditions, DS-OCT captured changes in the pattern of mucus hydration over time. DS-OCT opens a new window into understanding mechanisms of mucus thinning during treatment, enabling real-time efficacy feedback needed to optimize and tailor treatments for individual patients.

Transcranial diffuse optical assessment of the microvascular reperfusion after thrombolysis for acute ischemic stroke.

Science.gov (United States)

Delgado-Mederos, Raquel; Gregori-Pla, Clara; Zirak, Peyman; Blanco, Igor; Dinia, Lavinia; Marín, Rebeca; Durduran, Turgut; Martí-Fàbregas, Joan

2018-03-01

In this pilot study, we have evaluated bedside diffuse optical monitoring combining diffuse correlation spectroscopy and near-infrared diffuse optical spectroscopy to assess the effect of thrombolysis with an intravenous recombinant tissue plasminogen activator (rtPA) on cerebral hemodynamics in an acute ischemic stroke. Frontal lobes of five patients with an acute middle cerebral artery occlusion were measured bilaterally during rtPA treatment. Both ipsilesional and contralesional hemispheres showed significant increases in cerebral blood flow, total hemoglobin concentration and oxy-hemoglobin concentration during the first 2.5 hours after rtPA bolus. The increases were faster and higher in the ipsilesional hemisphere. The results show that bedside optical monitoring can detect the effect of reperfusion therapy for ischemic stroke in real-time.

Liquid sorption investigation of porous media by optical coherence tomography

International Nuclear Information System (INIS)

Fabritius, Tapio; Myllylae, Risto

2006-01-01

This paper introduces an alternative optical method to measuring liquid penetration into porous highly scattering media. Using pure glycerol, the method was tested by measuring glycerol sorption into cellulose fibre tissue with a grammage of 115 g m -2 . During the wetting process, dynamical changes in the scattering properties of the fibre tissue were detected by optical coherence tomography. Measurements were made from a single point on the front and back surface of a sample. Although the effect of penetration on the optical properties of a porous structure can be seen independent of measurement direction, the border between the dry and wetted area is detectable only in front surface measurements. In addition, the paper experimentally investigates the temporally and spatially dependent swelling behaviour of paper

Posterior Lattice Degeneration Characterized by Spectral Domain Optical Tomography

OpenAIRE

Manjunath, Varsha; Taha, Mohammed; Fujimoto, James G.; Duker, Jay S.

2011-01-01

PURPOSE: To utilize high-resolution spectral domain optical coherence tomography (SD-OCT) in the characterization of retinal and vitreal morphological changes overlying posterior lattice degeneration. METHODS: A cross-sectional, retrospective analysis was performed on 13 eyes of 13 nonconsecutive subjects with posterior lattice degeneration seen at the New England Eye Center, Tufts Medical Center between October 2009 and January 2010. SD-OCT images taken through the region of latti...

Noninvasive photoacoustic computed tomography of mouse brain metabolism in vivo

OpenAIRE

Yao, Junjie; Xia, Jun; Maslov, Konstantin I.; Nasiriavanaki, Mohammadreza; Tsytsarev, Vassiliy; Demchenko, Alexei V.; Wang, Lihong V.

2012-01-01

We have demonstrated the feasibility of imaging mouse brain metabolism using photoacoustic computed tomography (PACT), a fast, noninvasive and functional imaging modality with optical contrast and acoustic resolution. Brain responses to forepaw stimulations were imaged transdermally and transcranially. 2-NBDG, which diffuses well across the blood–brain-barrier, provided exogenous contrast for photoacoustic imaging of glucose response. Concurrently, hemoglobin provided endogenous contrast for ...

Optical calibration protocol for an x-ray and optical multimodality tomography system dedicated to small-animal examination

International Nuclear Information System (INIS)

Da Silva, Anabela; Leabad, Mehdi; Driol, Clemence; Bordy, Thomas; Debourdeau, Mathieu; Dinten, Jean-Marc; Peltie, Philippe; Rizo, Philippe

2009-01-01

A small-animal multimodality tomography system dedicated to the coregistration of fluorescence optical signal and x-ray measurements has been developed in our laboratory. The purpose of such a system is to offer the possibility of getting in vivo anatomical and functional information simultaneously. Moreover, anatomical measurements can be used as a regularization factor to achieve more accurate reconstructions of the biodistribution of fluorochromes and to speed up treatment. A dedicated acquisition protocol has been established, and the methodology of the reconstruction of the three-dimensional distribution of the biomarkers under cylindrical geometry consistent with classic computed tomography has been implemented. A phantom study was conducted to evaluate and to fix the parameters for the coregistration. These test experiments were reproduced by considering anesthetized mice that had thin glass tubes containing fluorochromes inserted into their esophagus. The instrument is also used for an in vivo biological study conducted on mice with lung tumors, tagged with near-infrared optical probes (targeting probes such as Transferin-AlexaFluor750)

Asymptotic solutions of numerical transport problems in optically thick, diffusive regimes

International Nuclear Information System (INIS)

Larsen, E.W.; Morel, J.E.; Miller, W.F. Jr.

1987-01-01

We present an asymptotic analysis of spatial differencing schemes for the discrete-ordinates equations, for diffusive media with spatial cells that are not optically thin. Our theoretical tool is an asymptotic expansion that has previously been used to describe the transform from analytic transport to analytic diffusion theory for such media. To introduce this expansion and its physical rationale, we first describe it for the analytic discrete-ordinates equations. Then, we apply the expansion to the spatially discretized discrete-ordinates equations, with the spatial mesh scaled in either of two physically relevant ways such that the optical thickness of the spatial cells is not small. If the result of either expansion is a legitimate diffusion description for either the cell-averaged or cell-edge fluxes, then we say that the approximate flux has the appropriate diffusion limit; otherwise, we say it does not. We consider several transport differencing schemes that are applicable in neutron transport and thermal radiation applications. We also include numerical results which demonstrate the validity of our theory and show that differencing schemes that do have a particular diffusion limit are substantially more accurate, in the regime described by the limit, than those that do not. copyright 1987 Academic Press, Inc

Portable, Fiber-Based, Diffuse Reflection Spectroscopy (DRS) Systems for Estimating Tissue Optical Properties.

Science.gov (United States)

Vishwanath, Karthik; Chang, Kevin; Klein, Daniel; Deng, Yu Feng; Chang, Vivide; Phelps, Janelle E; Ramanujam, Nimmi

2011-02-01

Steady-state diffuse reflection spectroscopy is a well-studied optical technique that can provide a noninvasive and quantitative method for characterizing the absorption and scattering properties of biological tissues. Here, we compare three fiber-based diffuse reflection spectroscopy systems that were assembled to create a light-weight, portable, and robust optical spectrometer that could be easily translated for repeated and reliable use in mobile settings. The three systems were built using a broadband light source and a compact, commercially available spectrograph. We tested two different light sources and two spectrographs (manufactured by two different vendors). The assembled systems were characterized by their signal-to-noise ratios, the source-intensity drifts, and detector linearity. We quantified the performance of these instruments in extracting optical properties from diffuse reflectance spectra in tissue-mimicking liquid phantoms with well-controlled optical absorption and scattering coefficients. We show that all assembled systems were able to extract the optical absorption and scattering properties with errors less than 10%, while providing greater than ten-fold decrease in footprint and cost (relative to a previously well-characterized and widely used commercial system). Finally, we demonstrate the use of these small systems to measure optical biomarkers in vivo in a small-animal model cancer therapy study. We show that optical measurements from the simple portable system provide estimates of tumor oxygen saturation similar to those detected using the commercial system in murine tumor models of head and neck cancer.

Dental calculus image based on optical coherence tomography

Science.gov (United States)

Hsieh, Yao-Sheng; Ho, Yi-Ching; Lee, Shyh-Yuan; Chuang, Ching-Cheng; Wang, Chun-Yang; Sun, Chia-Wei

2011-03-01

In this study, the dental calculus was characterized and imaged by means of swept-source optical coherence tomography (SSOCT). The refractive indices of enamel, dentin, cementum and calculus were measured as 1.625+/-0.024, 1.534+/-0.029, 1.570+/-0.021 and 1.896+/-0.085, respectively. The dental calculus lead strong scattering property and thus the region can be identified under enamel with SSOCT imaging. An extracted human tooth with calculus was covered by gingiva tissue as in vitro sample for SSOCT imaging.

Detection of bladder tumors using optical coherence tomography

Science.gov (United States)

Pan, Yingtian; Xie, Tuqiang; Wang, Zhenguo

2004-07-01

This paper summarizes the engineering development of our lab for endoscopic optical coherence tomography toward the ultimate goal to image bladder micro architecture and to diagnose bladder cancers. To test the utility and potential limitations of OCT setups for bladder tumor diagnosis, we used a rat bladder cancer model to track the morphological changes following tumor growth. Image results are presented, suggesting that OCT is able to differentiate cancerous lesions from inflammatory lesions based on OCT characterizations of epithelial thickness and backscattering changes of bladder tissue.

Infrared imaging and spectral-domain optical coherence tomography findings correlate with microperimetry in acute macular neuroretinopathy: a case report

Directory of Open Access Journals (Sweden)

Grover Sandeep

2011-10-01

Full Text Available Abstract Introduction Spectral-domain optical coherence tomography findings in a patient with acute macular neuroretinopathy, and correlation with functional defects on microperimetry, are presented. Case presentation A 25-year old Caucasian woman presented with bitemporal field defects following an upper respiratory tract infection. Her visual acuity was 20/20 in both eyes and a dilated fundus examination revealed bilateral hyperpigmentary changes in the papillomacular bundle. Our patient underwent further evaluation with spectral-domain optical coherence tomography, infrared and fundus autofluorescence imaging. Functional changes were assessed by microperimetry. Infrared imaging showed the classic wedge-shaped defects and spectral-domain optical coherence tomography exhibited changes at the inner segment-outer segment junction, with a thickened outer plexiform layer overlying these areas. Fluorescein and indocyanine green angiography did not demonstrate any perfusion defects or any other abnormality. Microperimetry demonstrated focal elevation in threshold correlating with the wedge-shaped defects in both eyes. Conclusion Spectral-domain optical coherence tomography findings provide new evidence of the involvement of the outer plexiform layer of the retina in acute macular neuroretinopathy.

Noninvasive measurement of glucose concentration on human fingertip by optical coherence tomography

Science.gov (United States)

Chen, Tseng-Lin; Lo, Yu-Lung; Liao, Chia-Chi; Phan, Quoc-Hung

2018-04-01

A method is proposed for determining the glucose concentration on the human fingertip by extracting two optical parameters, namely the optical rotation angle and the depolarization index, using a Mueller optical coherence tomography technique and a genetic algorithm. The feasibility of the proposed method is demonstrated by measuring the optical rotation angle and depolarization index of aqueous glucose solutions with low and high scattering, respectively. It is shown that for both solutions, the optical rotation angle and depolarization index vary approximately linearly with the glucose concentration. As a result, the ability of the proposed method to obtain the glucose concentration by means of just two optical parameters is confirmed. The practical applicability of the proposed technique is demonstrated by measuring the optical rotation angle and depolarization index on the human fingertip of healthy volunteers under various glucose conditions.

An instrument for small-animal imaging using time-resolved diffuse and fluorescence optical methods

International Nuclear Information System (INIS)

Montcel, Bruno; Poulet, Patrick

2006-01-01

We describe time-resolved optical methods that use diffuse near-infrared photons to image the optical properties of tissues and their inner fluorescent probe distribution. The assembled scanner uses picosecond laser diodes at 4 wavelengths, an 8-anode photo-multiplier tube and time-correlated single photon counting. Optical absorption and reduced scattering images as well as fluorescence emission images are computed from temporal profiles of diffuse photons. This method should improve the spatial resolution and the quantification of fluorescence signals. We used the diffusion approximation of the radiation transport equation and the finite element method to solve the forward problem. The inverse problem is solved with an optimization algorithm such as ART or conjugate gradient. The scanner and its performances are presented, together with absorption, scattering and fluorescent images obtained with it

Extraction of optical scattering parameters and attenuation compensation in optical coherence tomography images of multi-layered tissue structures

DEFF Research Database (Denmark)

Thrane, Lars; Frosz, Michael Henoch; Tycho, Andreas

2004-01-01

A recently developed analytical optical coherence tomography (OCT) model [Thrane et al., J. Opt. Soc. Am. A 17, 484 (2000)] allows the extraction of optical scattering parameters from OCT images, thereby permitting attenuation compensation in those images. By expanding this theoretical model, we...... have developed a new method for extracting optical scattering parameters from multilayered tissue structures in vivo. To verify this, we used a Monte Carlo (MC) OCT model as a numerical phantom to simulate the OCT signal for het-erogeneous multilayered tissue. Excellent agreement between the extracted......, and the results hold promise for expanding the functional imaging capabilities of OCT....

Fiberoptic microneedles: novel optical diffusers for interstitial delivery of therapeutic light.

Science.gov (United States)

Kosoglu, Mehmet A; Hood, Robert L; Rossmeisl, John H; Grant, David C; Xu, Yong; Robertson, John L; Rylander, Marissa Nichole; Rylander, Christopher G

2011-11-01

Photothermal therapies have limited efficacy and application due to the poor penetration depth of light inside tissue. In earlier work, we described the development of novel fiberoptic microneedles to provide a means to mechanically penetrate dermal tissue and deliver light directly into a localized target area.This paper presents an alternate fiberoptic microneedle design with the capability of delivering more diffuse, but therapeutically useful photothermal energy. Laser lipolysis is envisioned as a future clinical application for this design. A novel fiberoptic microneedle was developed using hydrofluoric acid etching of optical fiber to permit diffuse optical delivery. Microneedles etched for 10, 30, and 50 minutes, and an optical fiber control were compared with three techniques. First, red light delivery from the microneedles was evaluated by imaging the reflectance of the light from a white paper.Second, spatial temperature distribution of the paper in response to near-IR light (1,064 nm, 1 W CW) was recorded using infrared thermography. Third, ex vivo adipose tissue response during 1,064 nm, (5 W CW)irradiation was recorded with bright field microscopy. Acid etching exposed a 3 mm length of the fiber core, allowing circumferential delivery of light along this length. Increasing etching time decreased microneedle diameter, resulting in increased uniformity of red and 1,064 nm light delivery along the microneedle axis. For equivalent total energy delivery, thinner microneedles reduced carbonization in the adipose tissue experiments. We developed novel microscale optical diffusers that provided a more homogeneous light distribution from their surfaces, and compared performance to a flat-cleaved fiber, a device currently utilized in clinical practice. These fiberoptic microneedles can potentially enhance clinical laser procedures by providing direct delivery of diffuse light to target chromophores, while minimizing undesirable photothermal damage in adjacent

CAPILLARY NETWORK ALTERATIONS IN X-LINKED RETINOSCHISIS IMAGED ON OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY.

Science.gov (United States)

Romano, Francesco; Arrigo, Alessandro; Chʼng, Soon Wai; Battaglia Parodi, Maurizio; Manitto, Maria Pia; Martina, Elisabetta; Bandello, Francesco; Stanga, Paulo E

2018-06-05

To assess foveal and parafoveal vasculature at the superficial capillary plexus, deep capillary plexus, and choriocapillaris of patients with X-linked retinoschisis by means of optical coherence tomography angiography. Six patients with X-linked retinoschisis (12 eyes) and seven healthy controls (14 eyes) were recruited and underwent complete ophthalmologic examination, including best-corrected visual acuity, dilated fundoscopy, and 3 × 3-mm optical coherence tomography angiography macular scans (DRI OCT Triton; Topcon Corp). After segmentation and quality review, optical coherence tomography angiography slabs were imported into ImageJ 1.50 (NIH; Bethesda) and digitally binarized. Quantification of vessel density was performed after foveal avascular zone area measurement and exclusion. Patients were additionally divided into "responders" and "nonresponders" to dorzolamide therapy. Foveal avascular zone area resulted markedly enlarged at the deep capillary plexus (P < 0.001), particularly in nonresponders. Moreover, patients disclosed a significant deep capillary plexus rarefaction, when compared with controls (P: 0.04); however, a subanalysis revealed that this damage was limited to the fovea (P: 0.006). Finally, the enlargement of foveal avascular zone area positively correlated with a decline in best-corrected visual acuity (P: 0.01). Prominent foveal vascular impairment is detectable in the deep capillary plexus of patients with X-linked retinoschisis. Our results correlate with functional outcomes, suggesting a possible vascular role in X-linked retinoschisis clinical manifestations.

Optical coherence tomography--a new imaging method in ophthalmology.

Science.gov (United States)

Svorenova, I; Strmen, P; Olah, Z

2010-01-01

An improvement of examination methods in ophthalmology, technical digitalisation and knowledge of validity of examinations in various diseases contributes to early diagnostics, thereby leading to an opportunity for early treatment of eye disorders. Standard introduction of the so-called optical coherence tomography into the ophthamological clinical practice facilitated new options for a detailed analysis of pathological processes in the particular layers of the retina (Fig. 2, Ref. 5). Full Text (Free, PDF) www.bmj.sk.

Optical coherent tomography in diagnoses of peripheral retinal degenarations

OpenAIRE

O. G. Pozdeyeva; T. B. Shaimov; A. Yu. Galin; R. B. Shaimov; T. A. Shaimova; A. V. Zolotova; A. V. Fomin

2014-01-01

Purpose: Studying the capabilities of optical coherence tomography (RTVue-100, OPTOVUE, USA) in evaluation of peripheral retinal degenerations, vitreoretinal adhesions, adjacent vitreous body as well as measurement of morphometric data.Methods: The study included 189 patients (239 eyes) with peripheral retinal degeneration. 77 men and 112 women aged 18 to 84 underwent an ophthalmologic examination since November 2012 until October 2013. The peripheral retina was visualized with the help of op...

CHARACTERISTICS OF EPIRETINAL MEMBRANE REMNANT EDGE BY OPTICAL COHERENCE TOMOGRAPHY AFTER PARS PLANA VITRECTOMY.

Science.gov (United States)

Gaber, Raouf; You, Qi Sheng; Muftuoglu, Ilkay Kilic; Alam, Mostafa; Tsai, Frank F; Mendoza, Nadia; Freeman, William R

2017-11-01

To evaluate the incidence, characteristics, and the progression of epiretinal membrane (ERM) remnant edge seen by optical coherence tomography after ERM peeling. A retrospective chart review was conducted for 86 eyes of 85 consecutive patients who were diagnosed with ERM and underwent pars plana vitrectomy for epiretinal membrane peeling between 2013 and 2014. Data collected and analyzed included age, gender, preoperative and postoperative visual acuity, use of indocyanine green dye to stain internal limiting membrane, tamponade used after vitrectomy, ERM edge boundaries, presence of cystoid macular edema, and central foveal thickness. An ERM remnant edge was detected in 33/86 study eyes (38.4%) at the first postoperative optical coherence tomography scan. Compared with those without an ERM remnant, patients with an ERM remnant after surgery were significantly older at baseline and had a higher incidence of ERM recurrence at their last visit. They were not significantly different in terms of gender, preoperative and postoperative visual acuity, reduction of central foveal thickness from baseline, proportion of eyes with preoperative ERM elevation on optical coherence tomography, presence of macular edema before surgery, intraoperative use of indocyanine green staining for ILM peeling, or tamponade used. Based on the edge morphology, we classified the ERM remnant into three types: Type 1 was flat and blended with the retina (14/33 eyes, 42.4%), Type 2 was flat but stepped (17/33 eyes, 51.5%), and Type 3 was elevated (2/33 eyes, 6.0%). A significantly higher risk of ERM recurrence was seen in Type 2 and Type 3 ERM remnants (75% and 100%, respectively) than Type 1 ERM remnants (10%). An ERM remnant edge was detected by optical coherence tomography after ERM peeling in 38.4% of eyes. The presence of a postoperative ERM edge was associated with a higher risk of ERM recurrence, particularly in Type 2 and Type 3 ERM remnants.

Optical coherence tomography angiography in acute arteritic and non-arteritic anterior ischemic optic neuropathy.

Science.gov (United States)

Balducci, Nicole; Morara, Mariachiara; Veronese, Chiara; Barboni, Piero; Casadei, Nicoletta Lelli; Savini, Giacomo; Parisi, Vincenzo; Sadun, Alfredo A; Ciardella, Antonio

2017-11-01

The purpose of our study was to describe the feature of acute non-arteritic or arteritic anterior ischemic optic neuropathy (NA-AION and A-AION) using optical coherence tomography angiography (OCT-A) and to compare it with fluorescein angiography (FA) and indocyanine green angiography (ICGA). In this retrospective, observational case-control study four NA-AION patients and one A-AION patient were examined by FA, ICGA and OCT-A within 2 weeks from disease presentation. The characteristics of the images were analyzed. Optic nerve head (ONH) and radial peripapillary capillaries (RPC) vessel densities (VDs) were compared between NA-AION and controls. In two of four NA-AION cases and in the A-AION patient, OCT-A clearly identified the boundary of the ischemic area at the level of the optic nerve head, which was comparable to optic disc filling defects detected by FA. In the other two NA-AION cases, a generalized leakage from the disc was visible with FA, yet OCT-A still demonstrated sectorial peripapillary capillary network reduction. Both ONH and RPC VDs were reduced in NA-AION patients, when compared to controls. OCT-A was able to identify microvascular defects and VD reduction in cases of acute optic disc edema due to NA-AION and A-AION. OCT-A provides additional information in ischemic conditions of the optic nerve head.

Computed tomography of the optic nerve with special reference to the attenuation values

International Nuclear Information System (INIS)

Mimura, Osamu; Shimooku, Masashi; Sakamoto, Kiyoshi; Sakamoto, Taeko

1980-01-01

The value of computed tomography (CT) for ophthalmology needs no longer to be emphasized. Everything, however, has its limitations. In this article, the limitations of CT for the diagnosis of the optic nerve diameter were studied in an orbit-optic nerve model. The difference of 15 Hounsfield units between two scans which demonstrated the optic nerve having almost the same diameter, as a result of the partial volume effect, was obtained. This suggested that the attenuation values of the optic nerve are markedly influenced by the partial volume effect, and that they require further investigation for clinical use. (author)

Molecular imaging and optical diagnosis from single molecule to human body

International Nuclear Information System (INIS)

Tamura, Mamoru

2006-01-01

The combination of molecular biology and optelectronics has given rise to open a new field, bio-photonics, in the 21st century. In this review, recent advances in several in vitro and in vivo single-molecule detection methods for animals are discussed. The possible applications of optical diagnosis are also included, which are optical mammography, diffuse optical tomography and fluorescence endoscopy. The potential of the light use of in diagnosis is emphasized. (author)

Optical coherence tomography findings in methanol toxicity.

Science.gov (United States)

Klein, Kendra A; Warren, Alexis K; Baumal, Caroline R; Hedges, Thomas R

2017-01-01

Methanol toxicity poses a significant public health problem in developing countries, and in Southeast Asia, where the most common source of poisoning is via adulterated liquor in local drinks. Methanol toxicity can have devastating visual consequences and retinal specialists should be aware of the features of this toxic optic neuropathy. The authors report a case of severe systemic methanol toxicity and relatively mild optic neuropathy demonstrating unique retinal changes on optical coherence tomography (OCT). A previously healthy student developed ataxia, difficulty breathing and loss of consciousness hours after drinking homemade alcohol while traveling in Indonesia. She was found to have a serum pH of 6.79 and elevated methanol levels. She was treated with intravenous ethanol, methylprednisolone and sodium bicarbonate. When she awoke she had bilateral central scotomas. At presentation, she had central depression on visual field testing. OCT of the retinal nerve fiber layer (RNFL) was normal but ganglion cell layer analysis (GCL) showed highly selective loss of the nasal fibers in both eyes. Further, OCT of the macula demonstrated inner nuclear layer (INL) microcysts in the corresponding area of selective GCL loss in both eyes. The selective involvement of the papillomacular bundle fibers is common in toxic optic neuropathies and represents damage to the small caliber axons rich in mitochondria. Despite severe systemic toxicity, the relative sparing of the optic nerve in this case enabled characterization of the evolution of methanol toxicity with segmental GCL involvement and preservation of the RNFL, corresponding to the papillomacular bundle. This is the first reported case of INL microcysts in methanol optic neuropathy and supports that they are a non-specific finding, and may represent preferential damage to the papillomacular bundle.

Transient spectral domain optical coherence tomography findings in classic MEWDS: a case report.

Science.gov (United States)

Lavigne, Luciana Castro; Isaac, David Leonardo Cruvinel; Duarte Júnior, José Osório; Avila, Marcos Pereira de

2014-01-01

The purpose of this study was to describe a patient with multiple evanescent white dot syndrome (MEWDS) who presented with classic retinal findings and transient changes in outer retinal anatomy. A 20-year-old man presented with mild blurred vision in the left eye, reporting flu-like symptoms 1 week before the visual symptoms started. Fundus examination of the left eye revealed foveal granularity and multiple scattered spots deep to the retina in the posterior pole. Fluorescein angiography and indocyanine green angiography showed typical MEWDS findings. Spectral Domain Optical Coherence Tomography has shown transient changes in outer retinal anatomy with disappearance of inner segment-outer segment junction and mild attenuation of external limiting membrane. Six months later, Spectral Domain Optical Coherence Tomography has shown complete resolution with recovery of normal outer retinal aspect.

Optical Coherence Tomography

Directory of Open Access Journals (Sweden)

Pier Alberto Testoni

2007-01-01

Full Text Available Optical coherence tomography (OCT is an optical imaging modality that performs high-resolution, cross-sectional, subsurface tomographic imaging of the microstructure of tissues. The physical principle of OCT is similar to that of B-mode ultrasound imaging, except that it uses infrared light waves rather than acoustic waves. The in vivo resolution is 10–25 times better (about 10 µm than with high-frequency ultrasound imaging, but the depth of penetration is limited to 1–3 mm, depending on tissue structure, depth of focus of the probe used, and pressure applied to the tissue surface. In the last decade, OCT technology has evolved from an experimental laboratory tool to a new diagnostic imaging modality with a wide spectrum of clinical applications in medical practice, including the gastrointestinal tract and pancreatico-biliary ductal system. OCT imaging from the gastrointestinal tract can be done in humans by using narrow-diameter, catheter-based probes that can be inserted through the accessory channel of either a conventional front-view endoscope, for investigating the epithelial structure of the gastrointestinal tract, or a side-view endoscope, inside a standard transparent ERCP (endoscopic retrograde cholangiopancreatography catheter, for investigating the pancreatico-biliary ductal system. The esophagus and esophagogastric junction have been the most widely investigated organs so far; more recently, duodenum, colon, and the pancreatico-biliary ductal system have also been extensively investigated. OCT imaging of the gastrointestinal wall structure is characterized by a multiple-layer architecture that permits an accurate evaluation of the mucosa, lamina propria, muscularis mucosae, and part of the submucosa. The technique may therefore be used to identify preneoplastic conditions of the gastrointestinal tract, such as Barrett's epithelium and dysplasia, and evaluate the depth of penetration of early-stage neoplastic lesions. OCT imaging

Polarimetry noise in fiber-based optical coherence tomography instrumentation

Science.gov (United States)

Zhang, Ellen Ziyi; Vakoc, Benjamin J.

2011-01-01

High noise levels in fiber-based polarization-sensitive optical coherence tomography (PS-OCT) have broadly limited its clinical utility. In this study we investigate contribution of polarization mode dispersion (PMD) to the polarimetry noise. We develop numerical models of the PS-OCT system including PMD and validate these models with empirical data. Using these models, we provide a framework for predicting noise levels, for processing signals to reduce noise, and for designing an optimized system. PMID:21935044

Optical properties change in Te diffused As{sub 50}Se{sub 50} chalcogenide thin film

Energy Technology Data Exchange (ETDEWEB)

Naik, Ramakanta; Behera, M.; Panda, R.; Mishra, N. C. [Department of Physics, Utkal University, Bhubaneswar, 751004, Odisha (India)

2016-05-23

In the present report, we present the effect of Te diffusion into As{sub 50}Se{sub 50} thin film which changes the optical properties. The Te/As{sub 50}Se{sub 50} film was irradiated by a laser beam of 532 nm to study the diffusion mechanism due to photo induced effect. The As{sub 50}Se{sub 50}, Te/As{sub 50}Se{sub 50} films show a completely amorphous nature from X-ray diffraction study. A non direct transition was found for these films on the basis of optical transmission data carried out by Fourier Transform infrared Spectroscopy. The optical bandgap is found to be decreased with Te deposition and photo darkening phenomena is observed for the diffused film. The change in the optical constants are well supported by the corresponding change in different types of bonds which are being studied by X-ray photoelectron spectroscopy.

Fluorescence diffuse tomography of small animals with DsRed2 fluorescent protein

Science.gov (United States)

Turchin, I. V.; Plehanov, V. I.; Orlova, A. G.; Kamenskiy, V. A.; Kleshnin, M. S.; Shirmanova, M. V.; Shakhova, N. M.; Balalaeva, I. V.; Savitskiy, A. P.

2006-05-01

Fluorescent compounds are used as markers to diagnose oncological diseases, to study molecular processes typical for carcinogenesis, and to investigate metastasis formation and tumor regress under the influence of therapeutics. Different types of tomography, such as continuous wave (CW), frequency-domain (FD), and time-domain (TD) tomography, allow fluorescence imaging of tumors located deep in human or animal tissue. In this work, preliminary results of the frequency domain fluorescent diffuse tomography (FDT) method in application to DsRed2 protein as a fluorescent agent are presented. For the first step of our experiments, we utilized low-frequency amplitude modulation (1 kHz) of second harmonic of Nd: YAG (532 nm). The transilluminative configuration was used in the setup. The results of post mortem experiments with capsules containing DsRed2 inserted inside the esophagus of a 3-day-old hairless rat to simulate tumor are shown. An algorithm of processing fluorescent images based on calculating the zero of maximum curvature has been applied to detect fluorescent inclusion boundaries in the image. This work demonstrates the potential capability of the FDT method for imaging deep fluorescent tumors in human tissue or animal models of human cancer. Improvement of the setup can be accomplished by using high-frequency modulation (using a 110-MHz acoustooptical modulator).

The Optic Disc Drusen Studies Consortium Recommendations for Diagnosis of Optic Disc Drusen Using Optical Coherence Tomography

DEFF Research Database (Denmark)

Malmqvist, Lasse; Bursztyn, Lulu; Costello, Fiona

2018-01-01

imaging optical coherence tomography (EDI-OCT) has improved the visualization of more deeply buried ODD. There is, however, no consensus regarding the diagnosis of ODD using OCT. The purpose of this study was to develop a consensus recommendation for diagnosing ODD using OCT. METHODS: The members...... of the Optic Disc Drusen Studies (ODDS) Consortium are either fellowship trained neuro-ophthalmologists with an interest in ODD, or researchers with an interest in ODD. Four standardization steps were performed by the consortium members with a focus on both image acquisition and diagnosis of ODD. RESULTS......: Based on prior knowledge and experiences from the standardization steps, the ODDS Consortium reached a consensus regarding OCT acquisition and diagnosis of ODD. The recommendations from the ODDS Consortium include scanning protocol, data selection, data analysis, and nomenclature. CONCLUSIONS: The ODDS...

Using spectral-domain optical coherence tomography to detect optic neuropathy in patients with craniosynostosis.

Science.gov (United States)

Dagi, Linda R; Tiedemann, Laura M; Heidary, Gena; Robson, Caroline D; Hall, Amber M; Zurakowski, David

2014-12-01

Detecting and monitoring optic neuropathy in patients with craniosynostosis is a clinical challenge due to limited cooperation, and subjective measures of visual function. The purpose of this study was to appraise the correlation of peripapillary retinal nerve fiber layer (RNFL) thickness measured by spectral-domain ocular coherence tomography (SD-OCT) with indication of optic neuropathy based on fundus examination. The medical records of all patients with craniosynostosis presenting for ophthalmic evaluation during 2013 were retrospectively reviewed. The following data were abstracted from the record: diagnosis, historical evidence of elevated intracranial pressure, current ophthalmic evaluation and visual field results, and current peripapillary RNFL thickness. A total of 54 patients were included (mean age, 10.6 years [range, 2.4-33.8 years]). Thirteen (24%) had evidence of optic neuropathy based on current fundus examination. Of these, 10 (77%) demonstrated either peripapillary RNFL elevation and papilledema or depression with optic atrophy. Sensitivity for detecting optic atrophy was 88%; for papilledema, 60%; and for either form of optic neuropathy, 77%. Specificity was 94%, 90%, and 83%, respectively. Kappa agreement was substantial for optic atrophy (κ = 0.73) and moderate for papilledema (κ = 0.39) and for either form of optic neuropathy (κ = 0.54). Logistic regression indicated that peripapillary RNFL thickness was predictive of optic neuropathy (P optic neuropathy than visual field testing (likelihood ratio = 10.02; P = 0.002). Sensitivity and specificity of logMAR visual acuity in detecting optic neuropathy were 15% and 95%, respectively. Peripapillary RNFL thickness measured by SD-OCT provides adjunctive evidence for identifying optic neuropathy in patients with craniosynostosis and appears more sensitive at detecting optic atrophy than papilledema. Copyright © 2014 American Association for Pediatric Ophthalmology and Strabismus. Published by

Assessment of Optical Coherence Tomography Imaging in the Diagnosis of Non-Melanoma Skin Cancer and Benign Lesions Versus Normal Skin:

DEFF Research Database (Denmark)

Mogensen, Mette; Jørgensen, Thomas Martini; Nürnberg, Birgit Meincke

2009-01-01

BACKGROUND Optical coherence tomography (OCT) is an optical imaging technique that may be useful in diagnosis of non-melanoma skin cancer (NMSC). OBJECTIVES To describe OCT features in NMSC such as actinic keratosis (AK) and basal cell carcinoma (BCC) and in benign lesions and to assess the diagn......BACKGROUND Optical coherence tomography (OCT) is an optical imaging technique that may be useful in diagnosis of non-melanoma skin cancer (NMSC). OBJECTIVES To describe OCT features in NMSC such as actinic keratosis (AK) and basal cell carcinoma (BCC) and in benign lesions and to assess...

Changes of Radial Diffusivity and Fractional Anisotopy in the Optic Nerve and Optic Radiation of Glaucoma Patients

Directory of Open Access Journals (Sweden)

Tobias Engelhorn

2012-01-01

Full Text Available Purpose of this study was to evaluate with diffusion-tensor imaging (DTI changes of radial diffusivity (RD and fractional anisotropy (FA in the optic nerve (ON and optic radiation (OR in glaucoma and to determine whether changes in RD and FA correlate with disease severity. Therefore, glaucoma patients and controls were examined using 3T. Regions of interest were positioned on RD and FA maps, and mean values were calculated for ON and OR and correlated with optic nerve atrophy and reduced spatial-temporal contrast sensitivity (STCS of the retina. We found, that RD in glaucoma patients was significantly higher in the ON (0.74 ± 0.21 versus 0.58 ± 0.17⋅10−3 mm2 s−1; P0.77. In conclusion, DTI at 3 Tesla allows robust RD and FA measurements in the ON and OR. Hereby, the extent of RD increase and FA decrease in glaucoma correlate with established ophthalmological examinations.

Assessment of laser-induced acceleration effects in optical clearing of in vivo human skin by optical coherence tomography

International Nuclear Information System (INIS)

Zhan, Zhigang; Wei, Huajiang; Jin, Ying

2015-01-01

Laser irradiation is considered to be a promising innovative technology which has been developed in an attempt to increase transdermal drug delivery. In this study, a near-infrared CW diode laser (785 nm) was applied to increase permeability of glycerol solutions in human skin in vivo and improve the optical clearing efficacy. Results show that for both 15%v/v and 30%v/v glycerol, the permeability coefficient increased significantly if the detected area of the skin tissue was treated with laser irradiation before optical clearing agents (OCAs) were applied. This study based on optical coherence tomography imaging technique and optical clearing effect finds laser irradiation a new approach for enhancing the penetration of OCAs and accelerating the rate of transdermal drug delivery. (paper)

Assessment of laser-induced acceleration effects in optical clearing of in vivo human skin by optical coherence tomography

Science.gov (United States)

Zhan, Zhigang; Wei, Huajiang; Jin, Ying

2015-02-01

Laser irradiation is considered to be a promising innovative technology which has been developed in an attempt to increase transdermal drug delivery. In this study, a near-infrared CW diode laser (785 nm) was applied to increase permeability of glycerol solutions in human skin in vivo and improve the optical clearing efficacy. Results show that for both 15%v/v and 30%v/v glycerol, the permeability coefficient increased significantly if the detected area of the skin tissue was treated with laser irradiation before optical clearing agents (OCAs) were applied. This study based on optical coherence tomography imaging technique and optical clearing effect finds laser irradiation a new approach for enhancing the penetration of OCAs and accelerating the rate of transdermal drug delivery.

Are All Retinal Nerve Fiber Layer Defects on Optic Coherence Tomography Glaucomatous?

Science.gov (United States)

Gür Güngör, Sirel; Ahmet, Akman

2017-10-01

In this study, we investigated the patients who were referred to our clinic with a prediagnosis of glaucoma based on retinal nerve fiber layer (RNFL) defects on optic coherence tomography (OCT) but were determined to have nonglaucomatous RNLF defects upon detailed examination. The ophthalmic examination notes, OCT images, Heidelberg retinal tomography (HRT) II and fundus photographs of 357 patients were retrospectively evaluated. Final diagnoses of these patients were investigated. Of the 357 patients, 216 (60.5%) were diagnosed as open angle glaucoma, 33 (9.2%) as low-tension glaucoma, 39 (10.9%) as pre-perimetric glaucoma. The ophthalmic examinations of 14 patients (3.9%) were normal and there were no RNFL defects in OCT examinations after dilatation. In 39 patients (10.9%), the ophthalmic and optic disc examinations were completely normal and no etiologic factor explaining RNFL defects was found. Twenty-two eyes of 16 patients (4.5%) were included in this study (the mean age was 53.8±11.5 years; 9 men and 7 women). After detailed questioning of the medical history and systemic and neurologic examinations, a diagnosis of ischemic optic neuropathy was made in 11 eyes (10 patients) (2.8%), optic neuritis in 3 eyes (2 patients) (0.6%), optic disc drusen in 4 eyes (2 patients) (0.6%), pseudotumor cerebri in 2 eyes (1 patient) (0.3%), and cerebral palsy in 2 eyes (1 patient) (0.3%). Decrease in RNFL thickness on OCT images alone may be misleading in glaucoma examination. In cases where optic disc cupping is not evident, diagnosis should not be based on OCT RNFL examinations alone, and the patient's medical history, detailed ophthalmic examination, OCT optic disc parameters, HRT, and visual field tests should all be carefully evaluated together.

Applicability of a geometrical model coupled to computed tomography to characterize the transport properties of porous materials: comparison with through diffusion experiments

International Nuclear Information System (INIS)

Chagneau, Aurelie; Claret, Francis; Made, Benoit; Tuckermann, Juergen; Enzmann, Frieder; Schaefer, Thorsten

2012-01-01

Document available in extended abstract form only. The main objective of the present study is to characterize the evolution of diffusion properties of porous materials as influenced by porosity changes. When under geochemical perturbation, the rocks porosity evolves with dissolution/precipitation processes. The impact of changes in porosity on the diffusion phenomena are implemented in most geochemical models using Archie's law: D e /D 0 = ε m where D e and D 0 are the effective diffusivity and the diffusivity of the element in water in m 2 s -1 , respectively, e is the overall porosity and m is the cementation factor. The factor m is a function of pores geometry and compaction. Depending on the rock considered, its value ranges from 1 to 3. Moreover, as the porosity decreases the connectivity of pores changes. At low overall porosity, the effective porosity is the determining parameter affecting effective diffusivity. Therefore, the Archie's law needs to be modified to accurately predict geochemical migration of pollutants such as radio-elements in a dynamic system. Our experimental approach is divided in two complementary parts: (i) diffusion experiments conducted in hot-laboratory using radiotracers and (ii) time-dependant monitoring of porosity evolution in three dimensions using computed tomography (CT). For the two approaches, simplified systems are used to define the co-evolution of porosity and diffusivity using a minimum number of parameters, in order to optimize the understanding of the basics and determining processes. For this purpose, three materials are used in diffusion columns: (i) rods of porous ceramic, (ii) artificial silica beads of different particle sizes (SiLi R ) and (iii) purified sea sand (Merck R ). The precipitation of simple salts, celestite (SrSO 4 ) and strontianite (SrCO 3 ), is forced in the porous material once placed in diffusion columns. Celestite and strontianite were chosen for their fast precipitation kinetics, and because

Optical coherence tomography used for internal biometrics

Science.gov (United States)

Chang, Shoude; Sherif, Sherif; Mao, Youxin; Flueraru, Costel

2007-06-01

Traditional biometric technologies used for security and person identification essentially deal with fingerprints, hand geometry and face images. However, because all these technologies use external features of human body, they can be easily fooled and tampered with by distorting, modifying or counterfeiting these features. Nowadays, internal biometrics which detects the internal ID features of an object is becoming increasingly important. Being capable of exploring under-skin structure, optical coherence tomography (OCT) system can be used as a powerful tool for internal biometrics. We have applied fiber-optic and full-field OCT systems to detect the multiple-layer 2D images and 3D profile of the fingerprints, which eventually result in a higher discrimination than the traditional 2D recognition methods. More importantly, the OCT based fingerprint recognition has the ability to easily distinguish artificial fingerprint dummies by analyzing the extracted layered surfaces. Experiments show that our OCT systems successfully detected the dummy, which was made of plasticene and was used to bypass the commercially available fingerprint scanning system with a false accept rate (FAR) of 100%.

Functional optical coherence tomography: principles and progress

International Nuclear Information System (INIS)

Kim, Jina; Levinson, Howard; Brown, William; Maher, Jason R.; Wax, Adam

2015-01-01

In the past decade, several functional extensions of optical coherence tomography (OCT) have emerged, and this review highlights key advances in instrumentation, theoretical analysis, signal processing and clinical application of these extensions. We review five principal extensions: Doppler OCT (DOCT), polarization-sensitive OCT (PS-OCT), optical coherence elastography (OCE), spectroscopic OCT (SOCT), and molecular imaging OCT. The former three have been further developed with studies in both ex vivo and in vivo human tissues. This review emphasizes the newer techniques of SOCT and molecular imaging OCT, which show excellent potential for clinical application but have yet to be well reviewed in the literature. SOCT elucidates tissue characteristics, such as oxygenation and carcinogenesis, by detecting wavelength-dependent absorption and scattering of light in tissues. While SOCT measures endogenous biochemical distributions, molecular imaging OCT detects exogenous molecular contrast agents. These newer advances in functional OCT broaden the potential clinical application of OCT by providing novel ways to understand tissue activity that cannot be accomplished by other current imaging methodologies. (topical review)

Neuromyelitis optica and multiple sclerosis: Seeing differences through optical coherence tomography

Science.gov (United States)

Bennett, JL; de Seze, J; Lana-Peixoto, M; Palace, J; Waldman, A; Schippling, S; Tenembaum, S; Banwell, B; Greenberg, B; Levy, M; Fujihara, K; Chan, KH; Kim, HJ; Asgari, N; Sato, DK; Saiz, A; Wuerfel, J; Zimmermann, H; Green, A; Villoslada, P

2015-01-01

Neuromyelitis optica (NMO) is an inflammatory autoimmune disease of the central nervous system that preferentially targets the optic nerves and spinal cord. The clinical presentation may suggest multiple sclerosis (MS), but a highly specific serum autoantibody against the astrocytic water channel aquaporin-4 present in up to 80% of NMO patients enables distinction from MS. Optic neuritis may occur in either condition resulting in neuro-anatomical retinal changes. Optical coherence tomography (OCT) has become a useful tool for analyzing retinal damage both in MS and NMO. Numerous studies showed that optic neuritis in NMO typically results in more severe retinal nerve fiber layer (RNFL) and ganglion cell layer thinning and more frequent development of microcystic macular edema than in MS. Furthermore, while patients’ RNFL thinning also occurs in the absence of optic neuritis in MS, subclinical damage seems to be rare in NMO. Thus, OCT might be useful in differentiating NMO from MS and serve as an outcome parameter in clinical studies. PMID:25662342

Currently available methodologies for the processing of intravascular ultrasound and optical coherence tomography images.

Science.gov (United States)

Athanasiou, Lambros; Sakellarios, Antonis I; Bourantas, Christos V; Tsirka, Georgia; Siogkas, Panagiotis; Exarchos, Themis P; Naka, Katerina K; Michalis, Lampros K; Fotiadis, Dimitrios I

2014-07-01

Optical coherence tomography and intravascular ultrasound are the most widely used methodologies in clinical practice as they provide high resolution cross-sectional images that allow comprehensive visualization of the lumen and plaque morphology. Several methods have been developed in recent years to process the output of these imaging modalities, which allow fast, reliable and reproducible detection of the luminal borders and characterization of plaque composition. These methods have proven useful in the study of the atherosclerotic process as they have facilitated analysis of a vast amount of data. This review presents currently available intravascular ultrasound and optical coherence tomography processing methodologies for segmenting and characterizing the plaque area, highlighting their advantages and disadvantages, and discusses the future trends in intravascular imaging.

Optical coherence tomography imaging of the basal ganglia: feasibility and brief review

Energy Technology Data Exchange (ETDEWEB)

Lopez, W. O. Contreras; Ângelos, J. S. [Divisão de Neurocirurgia Funcional, Departamento de Neurologia, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP (Brazil); Martinez, R. C. R. [Laboratório de Neuromodulação e Dor Experimental, Hospital Sírio-Libanes, São Paulo, SP (Brazil); Takimura, C. K. [Instituto do Coração, Universidade de São Paulo, São Paulo, SP (Brazil); Teixeira, M. J. [Divisão de Neurocirurgia Funcional, Departamento de Neurologia, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP (Brazil); Lemos, P. A. Neto [Instituto do Coração, Universidade de São Paulo, São Paulo, SP (Brazil); Fonoff, E. T., E-mail: fonoffet@usp.br [Divisão de Neurocirurgia Funcional, Departamento de Neurologia, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP (Brazil)

2015-09-29

Optical coherence tomography (OCT) is a promising medical imaging technique that uses light to capture real-time cross-sectional images from biological tissues in micrometer resolution. Commercially available optical coherence tomography systems are employed in diverse applications, including art conservation and diagnostic medicine, notably in cardiology and ophthalmology. Application of this technology in the brain may enable distinction between white matter and gray matter, and obtainment of detailed images from within the encephalon. We present, herein, the in vivo implementation of OCT imaging in the rat brain striatum. For this, two male 60-day-old rats (Rattus norvegicus, Albinus variation, Wistar) were stereotactically implanted with guide cannulas into the striatum to guide a 2.7-French diameter high-definition OCT imaging catheter (Dragonfly™, St. Jude Medical, USA). Obtained images were compared with corresponding histologically stained sections to collect imaging samples. A brief analysis of OCT technology and its current applications is also reported, as well as intra-cerebral OCT feasibility on brain mapping during neurosurgical procedures.

Neurofibromatosis: an update of ophthalmic characteristics and applications of optical coherence tomography

Directory of Open Access Journals (Sweden)

Abdolrahimzadeh B

2016-05-01

Full Text Available Barmak Abdolrahimzadeh,1 Domenica Carmen Piraino,2 Giorgio Albanese,2 Filippo Cruciani,2 Siavash Rahimi3 1Polimed Beltramelli Medical Center, Rome, Italy; 2Section of Ophthalmology, Department of Sense Organs, University of Rome “Sapienza”, Rome, Italy; 3Pathology Centre, Queen Alexandra Hospital, Portsmouth, UK Abstract: Neurofibromatosis (NF is a multisystem disorder and tumor predisposition syndrome caused by genetic mutation on chromosome 17-17q11.2 in NF type 1 (NF1, and on chromosome 22-22q12.2 in NF type 2. The disorder is characterized by considerable heterogeneity of clinical expression. NF1 is the form with the most characteristic ocular manifestations. Lisch nodules of the iris are among the well-known diagnostic criteria for the disease. Glaucoma and associated globe enlargement have been described in a significant proportion of patients with NF1 and orbital–facial involvement. Optic nerve glioma may cause strabismus and proptosis, and palpebral neurofibroma may reach considerable size and occasionally show malignant transformation. Near infrared reflectance has greatly contributed to enhancing our knowledge on choroidal alterations in NF1. Indeed, some authors have proposed to include these among the diagnostic criteria. Optical coherence tomography has given new insight on retinal alterations and is a noninvasive tool in the management of optic nerve gliomas in children. Ocular manifestations in NF type 2 can range from early-onset cataracts in up to 80% of cases to optic nerve hamartomas and combined pigment epithelial and retinal hamartomas. Keywords: neurofibromatosis, ophthalmic, optical coherence tomography, infrared reflectance, choroideal nodules, Lisch nodules

Mechanisms of Very Late Drug-Eluting Stent Thrombosis Assessed by Optical Coherence Tomography

DEFF Research Database (Denmark)

Taniwaki, Masanori; Radu, Maria D; Zaugg, Serge

2016-01-01

BACKGROUND: The pathomechanisms underlying very late stent thrombosis (VLST) after implantation of drug-eluting stents (DES) are incompletely understood. Using optical coherence tomography, we investigated potential causes of this adverse event. METHODS AND RESULTS: Between August 2010 and Decemb...

Inflammatory Papillitis in Uveitis: Response to Treatment and Use of Optic Nerve Optical Coherence Tomography for Monitoring.

Science.gov (United States)

Cho, Heeyoon; Pillai, Parvathy; Nicholson, Laura; Sobrin, Lucia

2016-01-01

To describe the clinical course of uveitis-associated inflammatory papillitis and evaluate the utility and reproducibility of optic nerve spectral domain optical coherence tomography (SD-OCT). Data on 22 eyes of 14 patients with uveitis-related papillitis and optic nerve imaging were reviewed. SD-OCT measure reproducibility was determined and parameters were compared in active vs. inactive uveitis. Papillitis resolution lagged behind uveitis resolution in three patients. For SD-OCT measures, the intraclass correlation coefficients were 99.1-100% and 86.9-100% for intraobserver and interobserver reproducibility, respectively. All SD-OCT optic nerve measures except inferior and nasal peripapillary retinal thicknesses were significantly higher in active vs. inactive uveitis after correction for multiple hypotheses testing. Mean optic nerve central thickness decreased from 545.1 to 362.9 µm (p = 0.01). Resolution of inflammatory papillitis can lag behind resolution of uveitis. SD-OCT assessment of papillitis is reproducible and correlates with presence vs. resolution of uveitis.

Optical coherence tomography for diagnosing periodontal disease

Science.gov (United States)

Colston, Bill W., Jr.; Everett, Matthew J.; Da Silva, Luiz B.; Otis, Linda L.; Nathel, Howard

1997-05-01

We have, in this preliminary study, investigated the use of optical coherence tomography for diagnosis of periodontal disease. We took in vitro OCT images of the dental and periodontal tissues from a young pig and compared them to histological sections. These images distinguish tooth and soft tissue relationships that are important in diagnosing and assessing periodontal disease. We have imaged the attachment of gingiva to the tooth surface and located the cemento-enamel junction. This junction is an important reference point for defining attachment level in the diagnosis of periodontal disease. the boundary between enamel and dentin is also visible for most of the length of the anatomical crown, allowing quantitation of enamel thickness and character.

In vivo imaging of human photoreceptor mosaic with wavefront sensorless adaptive optics optical coherence tomography.

Science.gov (United States)

Wong, Kevin S K; Jian, Yifan; Cua, Michelle; Bonora, Stefano; Zawadzki, Robert J; Sarunic, Marinko V

2015-02-01

Wavefront sensorless adaptive optics optical coherence tomography (WSAO-OCT) is a novel imaging technique for in vivo high-resolution depth-resolved imaging that mitigates some of the challenges encountered with the use of sensor-based adaptive optics designs. This technique replaces the Hartmann Shack wavefront sensor used to measure aberrations with a depth-resolved image-driven optimization algorithm, with the metric based on the OCT volumes acquired in real-time. The custom-built ultrahigh-speed GPU processing platform and fast modal optimization algorithm presented in this paper was essential in enabling real-time, in vivo imaging of human retinas with wavefront sensorless AO correction. WSAO-OCT is especially advantageous for developing a clinical high-resolution retinal imaging system as it enables the use of a compact, low-cost and robust lens-based adaptive optics design. In this report, we describe our WSAO-OCT system for imaging the human photoreceptor mosaic in vivo. We validated our system performance by imaging the retina at several eccentricities, and demonstrated the improvement in photoreceptor visibility with WSAO compensation.

Optical coherence tomography-enhanced microlaryngoscopy: preliminary report of a noncontact optical coherence tomography system integrated with a surgical microscope.

Science.gov (United States)

Vokes, David E; Jackson, Ryan; Guo, Shuguang; Perez, Jorge A; Su, Jianping; Ridgway, James M; Armstrong, William B; Chen, Zhongping; Wong, Brian J F

2008-07-01

Optical coherence tomography (OCT) is a new imaging modality that uses near-infrared light to produce cross-sectional images of tissue with a resolution approaching that of light microscopy. We have previously reported use of OCT imaging of the vocal folds (VFs) during direct laryngoscopy with a probe held in contact or near-contact with the VFs. This aim of this study was to develop and evaluate a novel OCT system integrated with a surgical microscope to allow hands-free OCT imaging of the VFs, which could be performed simultaneously with microscopic visualization. We performed a prospective evaluation of a new method of acquiring OCT images of the VFs. An OCT system was successfully integrated with a surgical microscope to permit noncontact OCT imaging of the VFs of 10 patients. With this novel device we were able to identify VF epithelium and lamina propria; however, the resolution was reduced compared to that achieved with the standard contact or near-contact OCT. Optical coherence tomography is able to produce high-resolution images of vocal fold mucosa to a maximum depth of 1.6 mm. It may be used in the diagnosis of VF lesions, particularly early squamous cell carcinoma, in which OCT can show disruption of the basement membrane. Mounting the OCT device directly onto the operating microscope allows hands-free noncontact OCT imaging and simultaneous conventional microscopic visualization of the VFs. However, the lateral resolution of the OCT microscope system is 50 microm, in contrast to the conventional handheld probe system (10 microm). Although such images at this resolution are still useful clinically, improved resolution would enhance the system's performance, potentially enabling real-time OCT-guided microsurgery of the larynx.

Optical Coherence Tomography Study of Experimental Anterior Ischemic Optic Neuropathy and Histologic Confirmation

Science.gov (United States)

Ho, Joyce K.; Stanford, Madison P.; Shariati, Mohammad A.; Dalal, Roopa; Liao, Yaping Joyce

2013-01-01

Purpose. The optic nerve is part of the central nervous system, and interruption of this pathway due to ischemia typically results in optic atrophy and loss of retinal ganglion cells. In this study, we assessed in vivo retinal changes following murine anterior ischemic optic neuropathy (AION) by using spectral-domain optical coherence tomography (SD-OCT) and compared these anatomic measurements to that of histology. Methods. We induced ischemia at the optic disc via laser-activated photochemical thrombosis, performed serial SD-OCT and manual segmentation of the retinal layers to measure the ganglion cell complex (GCC) and total retinal thickness, and correlated these measurements with that of histology. Results. There was impaired perfusion and leakage at the optic disc on fluorescein angiography immediately after AION and severe swelling and distortion of the peripapillary retina on day-1. We used SD-OCT to quantify the changes in retinal thickness following experimental AION, which revealed significant thickening of the GCC on day-1 after ischemia followed by gradual thinning that plateaued by week-3. Thickness of the peripapillary sensory retina was also increased on day-1 and thinned chronically. This pattern of acute retinal swelling and chronic thinning on SD-OCT correlated well with changes seen in histology and corresponded to loss of retinal ganglion layer cells after ischemia. Conclusions. This was a serial SD-OCT quantification of acute and chronic changes following experimental AION, which revealed changes in the GCC similar to that of human AION, but over a time frame of weeks rather than months. PMID:23887804

INFORMATIVITY OF SPECTRAL OPTICAL COHERENT TOMOGRAPHY IN AGGRESSIVE POSTERIOR RETINOPATHY OF PREMATURITY

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A. V. Tereshchenko

2017-01-01

Full Text Available The purpose: to evaluate the informativity of optical coherence tomography in patients with aggressive posterior retinopathy of prematurity. Patients and methods. spectral optical coherence tomography using portable device iVue-100 with a removable camera (Optovue, USA was held in 32 children (64 eyes with aggressive posterior retinopathy of prematurity with a gestational period 26–31 week. Results. Children with aggressive posterior retinopathy of prematurity at the stage of early clinical manifestations, in addition to the indication that the immaturity of the retina, according to the spectral optical coherence tomography revealed only a few areas of epiretinal proliferation, which are not visualized with a digital retinoscopy and binocular indirect ophthalmoscopy. When the process is more pronounced in children with retinopathy of prematurity aggressive rear stage manifestation already determined multiple zones epiretinal proliferation as a "mushroom" and "flake" conglomerates with rear zone hyaloid membrane had an uneven seal. Coarser structural disorders of the retina and the vitreoretinal interface have been identified in patients with advancedstage aggressive posterior retinopathy of prematurity. We determined the shaft extraretinal proliferation as a "comb", as well as portions of epiretinal proliferation on the border of vascularized and avascular retina, which tended to merge, and the formation of massive hyperreflection complexes, lifted back hyaloid membrane, which was not only uneven sealed, but in some places is stratified. Conclusion. Despite the complexity of the procedure and the complexity of its implementation, the data obtained are particularly valuable and informative because they allow to complement the clinical picture and objectify it. It helps to choose the optimal tactics and improvement of a differentiated approach to the treatment of aggressive posterior retinopathy of prematurity.

Dual-Source Swept-Source Optical Coherence Tomography Reconstructed on Integrated Spectrum

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Shoude Chang

2012-01-01

Full Text Available Dual-source swept-source optical coherence tomography (DS-SSOCT has two individual sources with different central wavelengths, linewidth, and bandwidths. Because of the difference between the two sources, the individually reconstructed tomograms from each source have different aspect ratio, which makes the comparison and integration difficult. We report a method to merge two sets of DS-SSOCT raw data in a common spectrum, on which both data have the same spectrum density and a correct separation. The reconstructed tomographic image can seamlessly integrate the two bands of OCT data together. The final image has higher axial resolution and richer spectroscopic information than any of the individually reconstructed tomography image.

In vivo fluorescence enhanced optical tomography reconstruction of lung cancer of non immersed small animals

Science.gov (United States)

Hervé, L.; Koenig, A.; Da Silva, A.; Berger, M.; Boutet, J.; Dinten, J. M.; Peltié, P.; Rizo, P.

2007-02-01

Fluorescence enhanced diffuse optical tomography (fDOT) is envisioned to be useful to collect functional information from small animal models. For oncology applications, cancer-targeted fluorescent markers can be used as a surrogate of the cancer activity. We are developing a continuous wave fDOT bench intended to be integrated in systems dedicated to whole body small animal fluorescence analyses. The focus is currently put on the reconstruction of non immersed small animals imaged by a CCD camera. The reconstruction stage already corrects the tissue heterogeneity artifacts through the computation of an optical heterogeneity map. We will show how this formalism coupled with the determination of the animal boundaries performed by a laser scanner, can be used to manage non contact acquisitions. The time of reconstruction for a 10 × 9 laser source positions, 45 × 40 detector elements and 14 × 11 × 14 mesh voxels is typically 10 minutes on a 3GHz PCs corresponding to the acquisition time allowing the two tasks to be performed in parallel. The system is validated on an in vivo experiment performed on three healthy nude mice and a mouse bearing a lung tumor at 10, 12 and 14 days after implantation allowing the follow up of the disease. The 3D fluorescence reconstructions of this mouse are presented and the total fluorescence amounts are compared.

Offline fusion of co-registered intravascular ultrasound and frequency domain optical coherence tomography images for the analysis of human atherosclerotic plaques

DEFF Research Database (Denmark)

Räber, Lorenz; Heo, Jung Ho; Radu, Maria D

2012-01-01

To demonstrate the feasibility and potential usefulness of an offline fusion of matched optical coherence tomography (OCT) and intravascular ultrasound (IVUS)/virtual histology (IVUS-VH) images.......To demonstrate the feasibility and potential usefulness of an offline fusion of matched optical coherence tomography (OCT) and intravascular ultrasound (IVUS)/virtual histology (IVUS-VH) images....

Laser-ablated silicon nanoparticles: optical properties and perspectives in optical coherence tomography

International Nuclear Information System (INIS)

Kirillin, M Yu; Sergeeva, E A; Agrba, P D; Krainov, A D; Ezhov, A A; Shuleiko, D V; Kashkarov, P K; Zabotnov, S V

2015-01-01

Due to their biocompatibility silicon nanoparticles have high potential in biomedical applications, especially in optical diagnostics. In this paper we analyze properties of the silicon nanoparticles formed via laser ablation in water and study the possibility of their application as contrasting agents in optical coherence tomography (OCT). The nanoparticles suspension was produced by picosecond laser irradiation of monocrystalline silicon wafers in water. According to transmission electron microcopy analysis the silicon nanoparticles in the obtained suspension vary in size from 2 to 200 nm while concentration of the particles is estimated as 10 13 cm −3 . The optical properties of the suspension in the range from 400 to 1000 nm were studied by spectrophotometry measurements revealing a scattering coefficient of about 0.1 mm −1 and a scattering anisotropy factor in the range of 0.2–0.4. In OCT study a system with a central wavelength of 910 nm was employed. Potential of the silicon nanoparticles as a contrasting agent for OCT is studied in experiments with agarose gel phantoms. Topical application of the nanoparticles suspension allowed the obtaining of the contrast of structural features of phantom up to 14 dB in the OCT image. (paper)

MEMS-based non-rotatory circumferential scanning optical probe for endoscopic optical coherence tomography

Science.gov (United States)

Xu, Yingshun; Singh, Janak; Siang, Teo Hui; Ramakrishna, Kotlanka; Premchandran, C. S.; Sheng, Chen Wei; Kuan, Chuah Tong; Chen, Nanguang; Olivo, Malini C.; Sheppard, Colin J. R.

2007-07-01

In this paper, we present a non-rotatory circumferential scanning optical probe integrated with a MEMS scanner for in vivo endoscopic optical coherence tomography (OCT). OCT is an emerging optical imaging technique that allows high resolution cross-sectional imaging of tissue microstructure. To extend its usage to endoscopic applications, a miniaturized optical probe based on Microelectromechanical Systems (MEMS) fabrication techniques is currently desired. A 3D electrothermally actuated micromirror realized using micromachining single crystal silicon (SCS) process highlights its very large angular deflection, about 45 degree, with low driving voltage for safety consideration. The micromirror is integrated with a GRIN lens into a waterproof package which is compatible with requirements for minimally invasive endoscopic procedures. To implement circumferential scanning substantially for diagnosis on certain pathological conditions, such as Barret's esophagus, the micromirror is mounted on 90 degree to optical axis of GRIN lens. 4 Bimorph actuators that are connected to the mirror on one end via supporting beams and springs are selected in this micromirror design. When actuators of the micromirror are driven by 4 channels of sinusoidal waveforms with 90 degree phase differences, beam focused by a GRIN is redirected out of the endoscope by 45 degree tilting mirror plate and achieve circumferential scanning pattern. This novel driving method making full use of very large angular deflection capability of our micromirror is totally different from previously developed or developing micromotor-like rotatory MEMS device for circumferential scanning.

Diffuse infiltrating retinoblastoma invading subarachnoid space

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Kase S

2011-06-01

Full Text Available Satoru Kase1, Kazuhiko Yoshida1, Shigenobu Suzuki2, Koh-ichi Ohshima3, Shigeaki Ohno4, Susumu Ishida11Department of Ophthalmology, Hokkaido University Graduate School of Medicine, Sapporo; 2Department of Ophthalmic Oncology, National Cancer Center Hospital, Tokyo; 3Section of Ophthalmology, Okayama Medical Center, Okayama; 4Department of Ocular Inflammation and Immunology, Hokkaido University Graduate School of Medicine, Sapporo, JapanAbstract: We report herein an unusual case of diffuse infiltrating retinoblastoma involving the brain, which caused a patient’s death 27 months after enucleation. An eight-year-old boy complained of blurred vision in his right eye (OD in October 2006. Funduscopic examination showed optic disc swelling, dense whitish vitreous opacity, and an orange-colored subretinal elevated lesion adjacent to the optic disc. Fluorescein angiography revealed hyperfluorescence in the peripapillary region at an early-phase OD. Because the size of the subretinal lesion and vitreous opacity gradually increased, he was referred to us. His visual acuity was 20/1000 OD on June 20, 2007. Slit-lamp biomicroscopy showed a dense anterior vitreous opacity. Ophthalmoscopically, the subretinal orange-colored area spread out until reaching the mid peripheral region. A B-mode sonogram and computed tomography showed a thick homogeneous lesion without calcification. Gadolinium-enhanced magnetic resonance imaging showed a markedly enhanced appearance of the underlying posterior retina. Enucleation of the right eye was performed nine months after the initial presentation. Histopathology demonstrated retinal detachment and a huge choroidal mass invading the optic nerve head. The tumor was consistent with diffuse infiltrating retinoblastoma. The patient died due to brain involvement 27 months after enucleation. Ophthalmologists should be aware that diffuse infiltrating retinoblastoma may show an unfavorable course if its diagnosis is delayed

Optical computed tomography in PRESAGE® three-dimensional dosimetry: Challenges and prospective.

Science.gov (United States)

Khezerloo, Davood; Nedaie, Hassan Ali; Farhood, Bagher; Zirak, Alireza; Takavar, Abbas; Banaee, Nooshin; Ahmadalidokht, Isa; Kron, Tomas

2017-01-01

With the advent of new complex but precise radiotherapy techniques, the demands for an accurate, feasible three-dimensional (3D) dosimetry system have been increased. A 3D dosimeter system generally should not only have accurate and precise results but should also feasible, inexpensive, and time consuming. Recently, one of the new candidates for 3D dosimetry is optical computed tomography (CT) with a radiochromic dosimeter such as PRESAGE®. Several generations of optical CT have been developed since the 90s. At the same time, a large attempt has been also done to introduce the robust dosimeters that compatible with optical CT scanners. In 2004, PRESAGE® dosimeter as a new radiochromic solid plastic dosimeters was introduced. In this decade, a large number of efforts have been carried out to enhance optical scanning methods. This article attempts to review and reflect on the results of these investigations.

Optical computed tomography in PRESAGE® three-dimensional dosimetry: Challenges and prospective

Directory of Open Access Journals (Sweden)

Davood Khezerloo

2017-01-01

Full Text Available With the advent of new complex but precise radiotherapy techniques, the demands for an accurate, feasible three-dimensional (3D dosimetry system have been increased. A 3D dosimeter system generally should not only have accurate and precise results but should also feasible, inexpensive, and time consuming. Recently, one of the new candidates for 3D dosimetry is optical computed tomography (CT with a radiochromic dosimeter such as PRESAGE®. Several generations of optical CT have been developed since the 90s. At the same time, a large attempt has been also done to introduce the robust dosimeters that compatible with optical CT scanners. In 2004, PRESAGE® dosimeter as a new radiochromic solid plastic dosimeters was introduced. In this decade, a large number of efforts have been carried out to enhance optical scanning methods. This article attempts to review and reflect on the results of these investigations.

Three-dimensional imaging of artificial fingerprint by optical coherence tomography

Science.gov (United States)

Larin, Kirill V.; Cheng, Yezeng

2008-03-01

Fingerprint recognition is one of the popular used methods of biometrics. However, due to the surface topography limitation, fingerprint recognition scanners are easily been spoofed, e.g. using artificial fingerprint dummies. Thus, biometric fingerprint identification devices need to be more accurate and secure to deal with different fraudulent methods including dummy fingerprints. Previously, we demonstrated that Optical Coherence Tomography (OCT) images revealed the presence of the artificial fingerprints (made from different household materials, such as cement and liquid silicone rubber) at all times, while the artificial fingerprints easily spoofed the commercial fingerprint reader. Also we demonstrated that an analysis of the autocorrelation of the OCT images could be used in automatic recognition systems. Here, we exploited the three-dimensional (3D) imaging of the artificial fingerprint by OCT to generate vivid 3D image for both the artificial fingerprint layer and the real fingerprint layer beneath. With the reconstructed 3D image, it could not only point out whether there exists an artificial material, which is intended to spoof the scanner, above the real finger, but also could provide the hacker's fingerprint. The results of these studies suggested that Optical Coherence Tomography could be a powerful real-time noninvasive method for accurate identification of artificial fingerprints real fingerprints as well.

The application of optical coherence tomography angiography in retinal diseases.

Science.gov (United States)

Sambhav, Kumar; Grover, Sandeep; Chalam, Kakarla V

Optical coherence tomography angiography (OCTA) is a new, noninvasive imaging technique that generates real-time volumetric data on chorioretinal vasculature and its flow pattern. With the advent of high-speed optical coherence tomography, established enface chorioretinal segmentation, and efficient algorithms, OCTA generates images that resemble an angiogram. The principle of OCTA involves determining the change in backscattering between consecutive B-scans and then attributing the differences to the flow of erythrocytes through retinal blood vessels. OCTA has shown promise in the evaluation of common ophthalmologic diseases such as diabetic retinopathy, age-related macular degeneration, and retinal vascular occlusions. It quantifies vascular compromise reflecting the severity of diabetic retinopathy. OCTA detects the presence of choroidal neovascularization in exudative age-related macular degeneration and maps loss of choriocapillaris in nonexudative age-related macular degeneration. We describe principles of OCTA and findings in common and some uncommon retinal pathologies. Finally, we summarize its potential future applications. Its current limitations include a relatively small field of view, inability to show leakage, and a tendency for image artifacts. Further larger studies will define OCTAs utility in clinical settings and establish if the technology may offer its utility in decreasing morbidity through early detection and guide therapeutic interventions in retinal diseases. Copyright © 2017 Elsevier Inc. All rights reserved.

Algorithm of extraction optics properties from the measurement of spatially resolved diffuse reflectance

International Nuclear Information System (INIS)

Cunill Rodriguez, Margarita; Delgado Atencio, Jose Alberto; Castro Ramos, Jorge; Vazquez y Montiel, Sergio

2009-01-01

There are several methods to obtain the optical parameters of biological tissues from the measurement of spatially resolved diffuse reflectance. One of them is well-known as Video Reflectometry in which a camera CCD is used as detection and recording system of the lateral distribution of diffuse reflectance Rd(r) when an infinitely narrow light beam impinges on the tissue. In this paper, we present an algorithm that we have developed for the calibration and application of an experimental set-up of Video Reflectometry destined to extract the optical properties of models of biological tissues with optical properties similar to the human skin. The results of evaluation of the accuracy of the algorithm for optical parameters extraction is shown for a set of proofs reflectance curves with known values of these parameters. In the generation of these curves the simulation of measurement errors was also considered. The results show that it is possible to extract the optical properties with an accuracy error of less than 1% for all the proofs curves. (Author)

Retinal nerve fiber layer thickness map determined from optical coherence tomography images

NARCIS (Netherlands)

Mujat, M.; Chan, R. C.; Cense, B.; Park, B.H.; Joo, C.; Akkin, T.; Chen, TC; de Boer, JF

2005-01-01

We introduce a method to determine the retinal nerve fiber layer (RNFL) thickness in OCT images based on anisotropic noise suppression and deformable splines. Spectral-Domain Optical Coherence Tomography (SDOCT) data was acquired at 29 kHz A-line rate with a depth resolution of 2.6 mum and a depth

Assessing carotid atherosclerosis by fiber-optic multispectral photoacoustic tomography

Science.gov (United States)

Hui, Jie; Li, Rui; Wang, Pu; Phillips, Evan; Bruning, Rebecca; Liao, Chien-Sheng; Sturek, Michael; Goergen, Craig J.; Cheng, Ji-Xin

2015-03-01

Atherosclerotic plaque at the carotid bifurcation is the underlying cause of the majority of ischemic strokes. Noninvasive imaging and quantification of the compositional changes preceding gross anatomic changes within the arterial wall is essential for diagnosis of disease. Current imaging modalities such as duplex ultrasound, computed tomography, positron emission tomography are limited by the lack of compositional contrast and the detection of flow-limiting lesions. Although high-resolution magnetic resonance imaging has been developed to characterize atherosclerotic plaque composition, its accessibility for wide clinical use is limited. Here, we demonstrate a fiber-based multispectral photoacoustic tomography system for excitation of lipids and external acoustic detection of the generated ultrasound. Using sequential ultrasound imaging of ex vivo preparations we achieved ~2 cm imaging depth and chemical selectivity for assessment of human arterial plaques. A multivariate curve resolution alternating least squares analysis method was applied to resolve the major chemical components, including intravascular lipid, intramuscular fat, and blood. These results show the promise of detecting carotid plaque in vivo through esophageal fiber-optic excitation of lipids and external acoustic detection of the generated ultrasound. This imaging system has great potential for serving as a point-ofcare device for early diagnosis of carotid artery disease in the clinic.

Fast in vivo bioluminescence tomography using a novel pure optical imaging technique

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Shuang Zhang

2017-05-01

Full Text Available Bioluminescence tomography (BLT is a novel optical molecular imaging technique that advanced the conventional planar bioluminescence imaging (BLI into a quantifiable three-dimensional (3D approach in preclinical living animal studies in oncology. In order to solve the inverse problem and reconstruct tumor lesions inside animal body accurately, the prior structural information is commonly obtained from X-ray computed tomography (CT. This strategy requires a complicated hybrid imaging system, extensive post imaging analysis and involvement of ionizing radiation. Moreover, the overall robustness highly depends on the fusion accuracy between the optical and structural information. Here, we present a pure optical bioluminescence tomographic (POBT system and a novel BLT workflow based on multi-view projection acquisition and 3D surface reconstruction. This method can reconstruct the 3D surface of an imaging subject based on a sparse set of planar white-light and bioluminescent images, so that the prior structural information can be offered for 3D tumor lesion reconstruction without the involvement of CT. The performance of this novel technique was evaluated through the comparison with a conventional dual-modality tomographic (DMT system and a commercialized optical imaging system (IVIS Spectrum using three breast cancer xenografts. The results revealed that the new technique offered comparable in vivo tomographic accuracy with the DMT system (P>0.05 in much shorter data analysis time. It also offered significantly better accuracy comparing with the IVIS system (P<0.04 without sacrificing too much time.

Optical tomography of the aurora and EISCAT

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H. U. Frey

1998-10-01

Full Text Available Tomographic reconstruction of the three-dimensional auroral arc emission is used to obtain vertical and horizontal distributions of the optical auroral emission. Under the given experimental conditions with a very limited angular range and a small number of observers, algebraic reconstruction methods generally yield better results than transform techniques. Different algebraic reconstruction methods are tested with an auroral arc model and the best results are obtained with an iterative least-square method adapted from emission-computed tomography. The observation geometry used during a campaign in Norway in 1995 is tested with the arc model and root-mean-square errors, to be expected under the given geometrical conditions, are calculated. Although optimum geometry was not used, root-mean-square errors of less than 2% for the images and of the order of 30% for the distribution could be obtained. The method is applied to images from real observations. The correspondence of original pictures and projections of the reconstructed volume is discussed, and emission profiles along magnetic field lines through the three-dimensionally reconstructed arc are calibrated into electron density profiles with additional EISCAT measurements. Including a background profile and the temporal changes of the electron density due to recombination, good agreement can be obtained between measured profiles and the time-sequence of calculated profiles. These profiles are used to estimate the conductivity distribution in the vicinity of the EISCAT site. While the radar can only probe the ionosphere along the radar beam, the three-dimensional tomography enables conductivity estimates in a large area around the radar site.Key words. Tomography · Aurora · EISCAT · Ionosphere · Conductivity

Optical tomography of the aurora and EISCAT

Directory of Open Access Journals (Sweden)

H. U. Frey

Full Text Available Tomographic reconstruction of the three-dimensional auroral arc emission is used to obtain vertical and horizontal distributions of the optical auroral emission. Under the given experimental conditions with a very limited angular range and a small number of observers, algebraic reconstruction methods generally yield better results than transform techniques. Different algebraic reconstruction methods are tested with an auroral arc model and the best results are obtained with an iterative least-square method adapted from emission-computed tomography. The observation geometry used during a campaign in Norway in 1995 is tested with the arc model and root-mean-square errors, to be expected under the given geometrical conditions, are calculated. Although optimum geometry was not used, root-mean-square errors of less than 2% for the images and of the order of 30% for the distribution could be obtained. The method is applied to images from real observations. The correspondence of original pictures and projections of the reconstructed volume is discussed, and emission profiles along magnetic field lines through the three-dimensionally reconstructed arc are calibrated into electron density profiles with additional EISCAT measurements. Including a background profile and the temporal changes of the electron density due to recombination, good agreement can be obtained between measured profiles and the time-sequence of calculated profiles. These profiles are used to estimate the conductivity distribution in the vicinity of the EISCAT site. While the radar can only probe the ionosphere along the radar beam, the three-dimensional tomography enables conductivity estimates in a large area around the radar site.

Key words. Tomography · Aurora · EISCAT · Ionosphere · Conductivity

Performance analysis of a hybrid fingerprint extracted from optical coherence tomography fingertip scans

CSIR Research Space (South Africa)

Darlow, Luke N

2016-06-01

Full Text Available The Hybrid fingerprint is a local-quality-specific blend of the surface and internal fingerprints, extracted from optical coherence tomography scans. Owing to its origin, and the manner in which it is obtained, the Hybrid fingerprint is a high...

Frequency-swept Light Sources for Optical Coherence Tomography in the 1060nm range

DEFF Research Database (Denmark)

Marschall, Sebastian

Optical coherence tomography (OCT) is a non-invasive imaging technique for visualizing the internal structure of scattering materials, such as biological tissues. It generates two- or three-dimensional images of the sample with cellular (micrometer) resolution. OCT has become an important instrum...

Advanced Technologies for Ultrahigh Resolution and Functional Optical Coherence Tomography

Science.gov (United States)

2008-04-15

Gorczynska, "Frequency domain optical coherence tomography techniques in eye imaging," Acta Physica Polonica A , vol. 102, pp. 739-46, 2002/12/ 2002. [57] S...other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a ...SUPPLEMENTARY NOTES 14. ABSTRACT 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF: a . REPORT b. ABSTRACT c. THIS PAGE 17. LIMITATION OF ABSTRACT

Snapshot polarization-sensitive plug-in optical module for a Fourier-domain optical coherence tomography system

Science.gov (United States)

Marques, Manuel J.; Rivet, Sylvain; Bradu, Adrian; Podoleanu, Adrian

2018-02-01

In this communication, we present a proof-of-concept polarization-sensitive Optical Coherence Tomography (PS-OCT) which can be used to characterize the retardance and the axis orientation of a linear birefringent sample. This module configuration is an improvement from our previous work1, 2 since it encodes the two polarization channels on the optical path difference, effectively carrying out the polarization measurements simultaneously (snapshot measurement), whilst retaining all the advantages (namely the insensitivity to environmental parameters when using SM fibers) of these two previous configurations. Further progress consists in employing Master Slave OCT technology,3 which is used to automatically compensate for the dispersion mismatch introduced by the elements in the module. This is essential given the encoding of the polarization states on two different optical path lengths, each of them having dissimilar dispersive properties. By utilizing this method instead of the commonly used re-linearization and numerical dispersion compensation methods an improvement in terms of the calculation time required can be achieved.

Cystoid macular edema diagnosed with optical coherent tomography in patients operated on from cataract

International Nuclear Information System (INIS)

Diaz Arencibia, Omar; Rodriguez Rodriguez, Beatriz; Eguias Martinez, Frank; Alemany Rubio, Ernesto; Guerra, Roberto Alejandro

2009-01-01

Refers frequency of cystoid macular edema diagnosed with optical coherence tomography in patients operated on from senile cataract at 'Ramon Pando Ferrer' Cuban Institute of Ophthalmology in the period from December 2006 to February 2007

Investigation of optical coherence tomography as an imaging modality in tissue engineering

International Nuclear Information System (INIS)

Yang Ying; Dubois, Arnaud; Qin Xiangpei; Li Jian; Haj, Alicia El; Wang, Ruikang K

2006-01-01

Monitoring cell profiles in 3D porous scaffolds presents a major challenge in tissue engineering. In this study, we investigate optical coherence tomography (OCT) as an imaging modality to monitor non-invasively both structures and cells in engineered tissue constructs. We employ time-domain OCT to visualize macro-structural morphology, and whole-field optical coherence microscopy to delineate the morphology of cells and constructs in a developing in vitro engineered bone tissue. The results show great potential for the use of OCT in non-invasive monitoring of cellular activities in 3D developing engineered tissues

ULTRAHIGH SPEED SWEPT SOURCE OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY OF RETINAL AND CHORIOCAPILLARIS ALTERATIONS IN DIABETIC PATIENTS WITH AND WITHOUT RETINOPATHY.

Science.gov (United States)

Choi, WooJhon; Waheed, Nadia K; Moult, Eric M; Adhi, Mehreen; Lee, ByungKun; De Carlo, Talisa; Jayaraman, Vijaysekhar; Baumal, Caroline R; Duker, Jay S; Fujimoto, James G

2017-01-01

To investigate the utility of ultrahigh speed, swept source optical coherence tomography angiography in visualizing retinal microvascular and choriocapillaris (CC) changes in diabetic patients. The study was prospective and cross-sectional. A 1,050 nm wavelength, 400 kHz A-scan rate swept source optical coherence tomography prototype was used to perform volumetric optical coherence tomography angiography of the retinal and CC vasculatures in diabetic patients and normal subjects. Sixty-three eyes from 32 normal subjects, 9 eyes from 7 patients with proliferative diabetic retinopathy, 29 eyes from 16 patients with nonproliferative diabetic retinopathy, and 51 eyes from 28 diabetic patients without retinopathy were imaged. Retinal and CC microvascular abnormalities were observed in all stages of diabetic retinopathy. In nonproliferative diabetic retinopathy and proliferative diabetic retinopathy, optical coherence tomography angiography visualized a variety of vascular abnormalities, including clustered capillaries, dilated capillary segments, tortuous capillaries, regions of capillary dropout, reduced capillary density, abnormal capillary loops, and foveal avascular zone enlargement. In proliferative diabetic retinopathy, retinal neovascularization above the inner limiting membrane was visualized. Regions of CC flow impairment in patients with proliferative diabetic retinopathy and nonproliferative diabetic retinopathy were also observed. In 18 of the 51 of eyes from diabetic patients without retinopathy, retinal mircrovascular abnormalities were observed and CC flow impairment was found in 24 of the 51 diabetic eyes without retinopathy. The ability of optical coherence tomography angiography to visualize retinal and CC microvascular abnormalities suggests it may be a useful tool for understanding pathogenesis, evaluating treatment response, and earlier detection of vascular abnormalities in patients with diabetes.

Endoscopic optical coherence tomography for imaging the tympanic membrane