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Sample records for saggital optical tomography

  1. Optical tomography of tissues

    International Nuclear Information System (INIS)

    Methods of optical tomography of biological tissues are considered, which include pulse-modulation and frequency-modulation tomography, diffusion tomography with the use of cw radiation sources, optical coherent tomography, speckle-correlation tomography of nonstationary media, and optoacoustic tomography. The method for controlling the optical properties of tissues is studied from the point of view of increasing a probing depth in optical coherent tomography. The modern state and prospects of the development of optical tomography are discussed. (review)

  2. Optical Coherence Tomography

    Science.gov (United States)

    Related terms: OCT, optical imaging Optical coherence tomography (OCT) is a diagnostic procedure that is used in combination with a procedure called cardiac catheterization . The technique uses near-infrared light to ...

  3. Doppler Optical Coherence Tomography

    OpenAIRE

    Leitgeb, Rainer A.; Werkmeister, Rene? M.; Blatter, Cedric; Schmetterer, Leopold

    2014-01-01

    Optical Coherence Tomography (OCT) has revolutionized ophthalmology. Since its introduction in the early 1990s it has continuously improved in terms of speed, resolution and sensitivity. The technique has also seen a variety of extensions aiming to assess functional aspects of the tissue in addition to morphology. One of these approaches is Doppler OCT (DOCT), which aims to visualize and quantify blood flow. Such extensions were already implemented in time domain systems, but have gained impo...

  4. Optical Coherence Tomography

    DEFF Research Database (Denmark)

    Mogensen, Mette; Themstrup, Lotte

    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 optical analogue to ultrasound. The inherent safety of the technology allows for in vivo use of OCT in patients. The main strength of OCT is the depth resolution. In dermatology, most OCT research has turned on non-melanoma skin cancer (NMSC) and non-invasive monitoring of morphological changes in a number of skin diseases based on pattern recognition, and studies have found good agreement between OCT images and histopathological architecture. OCT has shown high accuracy in distinguishing lesions from normal skin, which is of great importance in identifying tumour borders or residual neoplastic tissue after therapy. The OCT images provide an advantageous combination of resolution and penetration depth, but specific studies of diagnostic sensitivity and specificity in dermatology are sparse. In order to improve OCT image quality and expand the potential of OCT, technical developments are necessary. It is suggested that the technology will be of particular interest to the routine follow-up of patients undergoing non-invasive therapy of malignant or premalignant keratinocyte tumours. It is speculated that the continued technological development can propel the method to a greater level of dermatological use.

  5. Second harmonic optical coherence tomography

    CERN Document Server

    Jiang, Y; Wang, Y; Chen, Z; Jiang, Yi; Tomov, Ivan; Wang, Yimin; Chen, Zhongping

    2004-01-01

    Second harmonic optical coherence tomography, which uses coherence gating of second-order nonlinear optical response of biological tissues for imaging, is described and demonstrated. Femtosecond laser pulses were used to excite second harmonic waves from collagen harvested from rat tail tendon and a reference nonlinear crystal. Second harmonic interference fringe signals were detected and used for image construction. Because of the strong dependence of second harmonic generation on molecular and tissue structures, this technique offers contrast and resolution enhancement to conventional optical coherence tomography.

  6. Second harmonic optical coherence tomography

    OpenAIRE

    Jiang, Yi; Tomov, Ivan; Wang, Yimin; Chen, Zhongping

    2004-01-01

    Second harmonic optical coherence tomography, which uses coherence gating of second-order nonlinear optical response of biological tissues for imaging, is described and demonstrated. Femtosecond laser pulses were used to excite second harmonic waves from collagen harvested from rat tail tendon and a reference nonlinear crystal. Second harmonic interference fringe signals were detected and used for image construction. Because of the strong dependence of second harmonic genera...

  7. Diffuse Optical Tomography

    Science.gov (United States)

    Yodh, Arjun

    2000-03-01

    Application of diffuse near-infrared (NIR) optical methods for imaging and spectroscopy of tissues is attractive for several reasons. The techniques utilize non-ionizing radiation, are non-invasive, and are often technologically simple and fast. The optical method also has several unique measurable parameters with potential to enhance tumor sensitivity and specificity. For example, blood dynamics, blood volume, blood oxygen saturation, and water content are often substantially different in the rapidly growing tumor, and will alter tissue optical absorption coefficients. An increase in organelle population, particularly mitochondria, accompanies the higher metabolic activity of the rapidly growing tumor, and leads to an increasing scattering coefficient for the tumor. Similarly the optical absorption, fluorescence, and scattering of contrast agents such as Indocyanine green (ICG) that occupy vascular and extravascular space provide useful forms of sensitization. In this paper I will discuss our work exploring the tumor contrasts accessible to the diffuse optical method, and I will describe how we extract this optical information using state-of-the-art theoretical, computational, and experimental technologies.

  8. Anterior Segment Tomography with the Cirrus Optical Coherence Tomography

    OpenAIRE

    Rodrigues, Eduardo B.; Margara Johanson; Penha, Fernando M.

    2012-01-01

    Optical coherence tomography (OCT) is an optical acquisition method to examine biological tissues. In recent years, OCT has become an important imaging technology used in diagnosing and following macular pathologies. Further development enabled application of optical coherence tomography in evaluation of the integrity of the nerve fiber layer, optic nerve cupping, anterior chamber angle, or corneal topography. In this manuscript we overview the use of OCT in the clinical practice to enable co...

  9. Artifacts in optical coherence tomography

    Science.gov (United States)

    Chhablani, Jay; Krishnan, Tandava; Sethi, Vaibhav; Kozak, Igor

    2014-01-01

    Optical coherence tomography (OCT) is now an integral part of management for numerous retinal diseases for diagnosis, treatment planning and follow up. OCT interpretation must involve the understanding of the associated artifacts. These artifacts can mislead physicians to wrong diagnosis or inappropriate management. This review article discusses the various types of artifacts in OCT scans obtained from various devices in various retinal diseases. This article would help to improve the understanding about the various artifacts and their clinical importance. PMID:24843299

  10. Flow-scanning optical tomography.

    Science.gov (United States)

    Pégard, Nicolas C; Toth, Marton L; Driscoll, Monica; Fleischer, Jason W

    2014-12-01

    We present a 3D tomography technique for in vivo observation of microscopic samples. The method combines flow in a microfluidic channel, illumination through a slit aperture, and a Fourier lens for simultaneous acquisition of multiple perspective angles in the phase-space domain. The technique is non-invasive and naturally robust to parasitic sample motion. 3D absorption is retrieved using standard back-projection algorithms, here a limited-domain inverse radon transform. Simultaneously, 3D differential phase contrast images are obtained by computational refocusing and comparison of complementary illumination angles. We implement the technique on a modified glass slide which can be mounted directly on existing optical microscopes. We demonstrate both amplitude and phase tomography on live, freely swimming C. elegans nematodes. PMID:25256716

  11. Adaptive Optics in Ocular Optical Coherence Tomography

    Science.gov (United States)

    Fernández, Enrique Josua; Artal, Pablo

    Adaptive optics (AO) is a technology for correcting aberrations in real time. When applied to the human eye, it has the potential of perfect imaging, from an optical perspective, the retina. Once aberrations from the eye have been compensated, theoretical resolution achievable in the living retina is 2-3 ?m. Therefore, individual cells and most of the morphological structures on the retina could be in principle imaged. Optical coherence tomography (OCT) has benefitted from this novel technique since 2004. The singularities of OCT, mainly the confocal detection and the mandatory use of broadband spectral light sources, imposes particular methods when applying AO. In a few years, many advances in the combination of AO with OCT have emerged. The in vivo images obtained with that modality have unveiled amazing details of the intraretinal tissue. In this chapter, both the theory and the practice of merging AO with OCT, with special emphasis on ultrahigh-resolution (UHR) OCT, will be presented and discussed.

  12. Catheters for optical coherence tomography

    International Nuclear Information System (INIS)

    The objective of this review article is to overview technology, clinical evidence, and future applications to date optical coherence tomography (OCT) probes to yield the diagnostic purpose. We have reviewed the designing, construction and working of different categories of OCT probes developed for optical diagnostics having a potential for non invasive and improved detection of different types of cancer as well as other neoplasm. Rotational and balloon catheters, imaging needles and hand-held, linear scanning, multichannel, micro electro mechanical systems (MEMS) technology based, dynamic focusing, forward view imaging, and common path interferometer based probes have been discussed in details. The fiber probes have shown excellent performance for two dimensional and three dimensional higher resolution, cross-sectional imaging of interior and exterior body tissues that can be compared with histopathology to provide the information about the angiogenesis and other lesions in the tissue. The MEMS-technology based probes are found to be more suitable for three dimensional morphological imaging

  13. 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 ?m, 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.

  14. Local Inversions in Ultrasound Modulated Optical Tomography

    OpenAIRE

    Bal, Guillaume; Moskow, Shari

    2013-01-01

    Ultrasound modulated optical tomography, also called acousto-optics 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 Schotland PRL 2010]. We present sufficient conditions ensuring that the absorption and diffusion coefficients modeling light propagation can locally be unique...

  15. Optical Coherence Tomography: Advanced Modeling

    DEFF Research Database (Denmark)

    Andersen, Peter E.; Thrane, Lars

    2013-01-01

    Analytical and numerical models for describing and understanding the light propagation in samples imaged by optical coherence tomography (OCT) systems are presented. An analytical model for calculating the OCT signal based on the extended Huygens-Fresnel principle valid both for the single- and multiple-scattering regimes is derived. An advanced Monte Carlo model for calculating the OCT signal is also derived, and the validity of this model is shown through a mathematical proof based on the extended Huygens-Fresnel principle. From the analytical model, an algorithm for enhancing OCT images is developed, the so-called true-reflection algorithm in which the OCT signal may be corrected for the attenuation caused by scattering. The algorithm is verified experimentally and by using the Monte Carlo model as a numerical tissue phantom. Applications of extraction of optical properties from tissue are discussed. Finally, the Wigner phase-space distribution function is derived in a closed-form solution, which may have applications in OCT.

  16. MOEMS optical delay line for optical coherence tomography

    Science.gov (United States)

    Choudhary, Om P.; Chouksey, S.; Sen, P. K.; Sen, P.; Solanki, J.; Andrews, J. T.

    2014-09-01

    Micro-Opto-Electro-Mechanical optical coherence tomography, a lab-on-chip for biomedical applications is designed, studied, fabricated and characterized. To fabricate the device standard PolyMUMPS processes is adopted. We report the utilization of electro-optic modulator for a fast scanning optical delay line for time domain optical coherence tomography. Design optimization are performed using Tanner EDA while simulations are performed using COMSOL. The paper summarizes various results and fabrication methodology adopted. The success of the device promises a future hand-held or endoscopic optical coherence tomography for biomedical applications.

  17. Conical wavefronts in optics and tomography

    International Nuclear Information System (INIS)

    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

  18. Optical tomography problems at layered media

    International Nuclear Information System (INIS)

    In the present work, problems of optical diagnostics for inhomogeneous layered media are studied by the methods of the radiation transfer theory. A method for finding the relative refraction indices and optical layers thickness based on the results of tomography transmission measurements under a special type of external radiation source is proposed

  19. Towards multimodal nonlinear optical tomography – experimental methodology

    International Nuclear Information System (INIS)

    All-optical microspectroscopic and tomographic tools reveal great potential for clinical dermatologic diagnostics, i.e., investigation of human skin and skin diseases. While optical-coherence tomography has been complemented by two-photon fluorescence tomography and second-harmonic generation tomography, a joint study of various nonlinear optical microspectroscopies, i.e., application of the recently developed multimodal imaging approach, to sizable human-tissue samples has not been evaluated up to now. Here, we present such multimodal approach combining different nonlinear optical contrast mechanisms for imaging, namely two-photon excited fluorescence (TPF), second-harmonic generation (SHG), and coherent anti-Stokes Raman scattering (CARS) into a joint microscopic experiment. We show the potential of imaging large skin areas and discuss the information obtained in a case study comparing normal skin and keloid tissue

  20. Towards model-based adaptive optics optical coherence tomography.

    Science.gov (United States)

    Verstraete, Hans R G W; Cense, Barry; Bilderbeek, Rolf; Verhaegen, Michel; Kalkman, Jeroen

    2014-12-29

    The transfer function for optical wavefront aberrations in single-mode fiber based optical coherence tomography is determined. The loss in measured OCT signal due to optical wavefront aberrations is quantified using Fresnel propagation and the calculation of overlap integrals. A distinction is made between a model for a mirror and a scattering medium model. The model predictions are validated with measurements on a mirror and a scattering medium obtained with an adaptive optics optical coherence tomography setup. Furthermore, a one-step defocus correction, based on a single A-scan measurement, is derived from the model and verified. Finally, the pseudo-convex structure of the optical coherence tomography transfer function is validated with the convergence of a hill climbing algorithm. The implications of this model for wavefront sensorless aberration correction are discussed. PMID:25607203

  1. Information theoretic regularization in diffuse optical tomography

    OpenAIRE

    Panagiotou, C.

    2011-01-01

    Diffuse optical tomography (DOT) retrieves the spatially distributed optical characteristics of a medium from external measurements. Recovering these parameters of interest involves solving a non-linear and severely ill-posed inverse problem. In this thesis we propose methods towards the regularization of DOT via the introduction of spatially unregistered, a priori information from alternative high resolution anatomical modalities, using the information theory concepts of joint en...

  2. Blind dispersion compensation for optical coherence tomography

    CERN Document Server

    Banaszek, K; Walmsley, I A; Banaszek, Konrad; Radunsky, Aleksandr S.; Walmsley, Ian A.

    2004-01-01

    We propose a numerical method for compensating dispersion effects in optical coherence tomography that does not require a priori knowledge of dispersive properties of the sample. The method is based on the generalized autoconvolution function, and its principle of operation can be intuitively visualized using the Wigner distribution function formalism.

  3. 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)

  4. Optical coherence tomography using a frequency-tunable optical source.

    Science.gov (United States)

    Chinn, S R; Swanson, E A; Fujimoto, J G

    1997-03-01

    We have developed a simple, wide-optical-bandwidth, high-resolution system for performing rapid optical frequency domain reflectometry measurements and applied it to multidimensional tomographic imaging. The source is a grating-tuned external cavity semiconductor laser with a tuning capability of 25 nm in 100 ms. We discuss system performance and show a two-dimensional optical coherence tomography image of a thin glass sandwich structure as a preliminary demonstration of the systems depth and resolution capabilities. PMID:18183195

  5. Thermo-optical delay line for optical coherence tomography:

    OpenAIRE

    Margallo-balbas, E.; Pandraud, G.; French, P. J.

    2007-01-01

    Optical Coherence Tomography (OCT) is a powerful medical imaging technology. Its ability to non-invasively probe tissues in depth with high resolution has lead to applications in many fields of medicine, with a large potential for surgical guidance. One of the technological challenges impairing faster adoption of OCT is the relative complexity of the corresponding optical instrumentation, which translates into expensive and bulky setups. In this paper a compact fastscanning optical delay line...

  6. Diffuse optical tomography guided adaptive reconstruction in fluorescence molecular tomography

    Science.gov (United States)

    Li, Mingze; Liu, Fei; Zhang, Bin; Bai, Jing

    2012-04-01

    The adaptive finite element method (AFEM) is an effective way to retain enough resolution in selected regions while improving computational efficiency for reconstruction in fluorescent molecular tomography (FMT). In addition, background optical properties acquired by diffuse optical tomography (DOT) will improve the quality of reconstructed images. In this work, a DOT-guided adaptive reconstruction method (DGARM) is proposed, in which DOT is introduced into an adaptive reconstruction framework of FMT. Besides being used as functional a priori information in the forward modeling, the reconstructed local absorption coefficients in DOT are also used to form internal structural a priori information, which is further used to identify regions of interest (ROIs) in the mesh refinement of the adaptive procedure. Because optical properties are recovered before the formulation of FMT, a linear relationship is established between the fluorescent field and boundary measurements. We implemented numerical simulations and physical experiments to evaluate the performance of the algorithm. Compared with the strategies of uniform meshing with DOT and AFEM without DOT, DGAM improves localization accuracy of the reconstruction of fluorescence inclusion.

  7. Single-Scattering Optical Tomography

    CERN Document Server

    Markel, V A; Markel, Vadim A.; Schotland, John C.

    2007-01-01

    We describe a novel tomographic imaging modality. The proposed technique utilizes visible or near-infrared light as a tissue probe in the ``mesoscopic'' scattering regime when the tissue layer exhibits sufficiently strong scattering so that its direct visual inspection is not possible, yet transmitted and reflected light are not diffuse. The forward model for light propagation in tissues is based on the scattering-order expansion of the radiative transport equation Green's function. The associated inverse problem is similar to the problem of inverting the Radon transform of x-ray tomography, except that the ray integrals are evaluated not along straight lines but along broken rays. As a result, the method does not require rotating the imaging device around the sample and taking multiple projections and, therefore, can be used in backscattering. An algebraic image reconstruction algorithm is numerically implemented using computer-generated data. An analytic image reconstruction formula analogous to the filtere...

  8. 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 

  9. Optical Phase-Space-Time-Frequency Tomography

    CERN Document Server

    Rojas, Paul; Sua, Yong Meng; Lee, Kim Fook

    2011-01-01

    We present a theoretical approach of constructing optical phase-space-time-frequency tomography (OPSTFT). This tomography can be measured by using a novel four-window optical imaging system based on two local oscillator fields balanced heterodyne detection. The OPSTFT is a Wigner distribution function of two independent Fourier Transform pairs, i.e., phase-space and time-frequency. From its theoretical and experimental aspects, it can provide information of position, momentum, time and frequency of a spatial light field with precision beyond the uncertainty principle limit. We believe that the four-window system can provide spatial and temporal properties of a wave field for quantum image processing and biophotonics.

  10. Optical tomography of the neonatal brain

    Energy Technology Data Exchange (ETDEWEB)

    Hebden, Jeremy C. [University College London, Department of Medical Physics and Bioengineering, London (United Kingdom); Austin, Topun [University College London, Department of Paediatrics and Child Health, London (United Kingdom)

    2007-11-15

    A new method of assessing neurological function and pathology in the newborn infant is being developed based on the transmission of near-infrared light across the brain. Absorption by blood over a range of wavelengths reveals a strong dependency on oxygenation status, and measurements of transmitted light enable the spatial variation in the concentrations of the oxygenated and de-oxygenated forms of hemoglobin to be derived. Optical tomography has so far provided static three-dimensional maps of blood volume and oxygenation as well as dynamic images revealing the brain's response to sensory stimulation and global hemodynamic changes. The imaging modality is being developed as a safe and non-invasive tool that can be utilized at the cotside in intensive care. Optical tomography of the healthy infant brain is also providing a means of studying neurophysiological processes during early development and the potential consequences of prematurity. (orig.)

  11. Quantum optical coherence tomography with dispersion cancellation

    CERN Document Server

    Abouraddy, A F; Saleh, B E A; Sergienko, A V; Teich, M C; Abouraddy, Ayman F.; Nasr, Magued B.; Saleh, Bahaa E. A.; Sergienko, Alexander V.; Teich, Malvin C.

    2002-01-01

    We propose a new technique, called quantum optical coherence tomography (QOCT), for carrying out tomographic measurements with dispersion-cancelled resolution. The technique can also be used to extract the frequency-dependent refractive index of the medium. QOCT makes use of a two-photon interferometer in which a swept delay permits a coincidence interferogram to be traced. The technique bears a resemblance to classical optical coherence tomography (OCT). However, it makes use of a nonclassical entangled twin-photon light source that permits measurements to be made at depths greater than those accessible via OCT, which suffers from the deleterious effects of sample dispersion. Aside from the dispersion cancellation, QOCT offers higher sensitivity than OCT as well as an enhancement of resolution by a factor of 2 for the same source bandwidth. QOCT and OCT are compared using an idealized sample.

  12. Optical Coherence Tomography: Potential Clinical Applications

    OpenAIRE

    Karanasos, Antonios; Ligthart, Jurgen; Witberg, Karen; Soest, Gijs; Bruining, Nico; Regar, Evelyn

    2012-01-01

    Optical coherence tomography (OCT) is a novel intravascular imaging modality using near-infrared light. By OCT it is possible to obtain high-resolution cross-sectional images of the vascular wall structure and assess the acute and long-term effects of percutaneous coronary intervention. For the time being OCT has been mainly used in research providing new insights into the pathophysiology of the atheromatic plaque and of the vascular response to stenting, however, it seems that there is poten...

  13. Optical Coherence Tomography and Fibrous Cap Characterization

    OpenAIRE

    Chamie?, Daniel; Wang, Zhao; Bezerra, Hiram; Rollins, Andrew M.; Costa, Marco A.

    2011-01-01

    The pathophysiology of acute coronary syndromes has long been associated with atherosclerotic plaque rupture. Inflammation, thinning, and disruption of the fibrous cap have been implicated with the final processes leading to plaque rupture, but confirmation of these mechanisms of coronary thrombosis in humans has been hampered by the lack of imaging methods with sufficient resolution to resolve fibrous cap characterization and thickness in vivo. Intravascular optical coherence tomography (OCT...

  14. Optical Coherence Tomography: A Concept Review

    Science.gov (United States)

    Serranho, Pedro; Morgado, António Miguel; Bernardes, Rui

    Optical coherence tomography (OCT) is an imaging modality broadly used in biological tissue imaging. In this chapter, we review the history of OCT and its development throughout the last years. We will focus on the physical concept of OCT imaging of the eye fundus, considering several settings currently used. We also list some research directions of recent and ongoing work concerned with the future developments of the technique and its application.

  15. Optical coherence tomography for quantitative surface topography

    OpenAIRE

    Ortiz, Sergio; Siedlecki, Damian; Remo?n, Laura; Marcos, Susana

    2009-01-01

    We address the measurement and correction of fan distortion in optical coherence tomography (OCT). This effect arises from the scanning system configuration and prevents one, in general, from obtaining quantitative topographic data from OCT. Computer simulations allowed us to quantify the effect and evaluate its dependence on the scanning mirror separation and design of the collimating lens, as well as to estimate the optimal axial position of that lens to minimize the fan distortion. We also...

  16. Optical coherence tomography findings of quinine poisoning

    OpenAIRE

    John Christoforidis; Robert Ricketts; Theodore Loizos; et al.

    2011-01-01

    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 comple...

  17. Optical Coherence Tomography for Artwork Diagnostics

    International Nuclear Information System (INIS)

    An overview of the optical coherence tomography (OCT) technique is given. Time domain, spectral and sweep source modalities are briefly described, and important physical parameters of the OCT instrument are discussed. Examples of the application of OCT to diagnosis of various art objects such as oil paintings on canvas (imaging of glaze and varnish layers), porcelain, faience, and parchment are presented. Applications to surface profilometry of painting on canvas are also discussed.

  18. Absolute LIBS stratigraphy with optical coherence tomography

    Science.gov (United States)

    Kwiatkowska, Ewa A.; Marczak, Jan; Ostrowski, Roman; Skrzeczanowski, Wojciech; Sylwestrzak, Marcin; Iwanicka, Magdalena; Targowski, Piotr

    2009-07-01

    In this contribution preliminary studies on the application of Optical Coherence Tomography (OCT) to absolute depth calibration of Laser Induced Breakdown Spectroscopy (LIBS) data in application to revealing stratigraphy of easel paintings are presented. The procedure of in-situ monitoring of LIBS by means of OCT is described. Numerical method developed for precise extraction of the depth of the LIBS ablation crater is explained. Results obtained with model paintings are discussed.

  19. Endoscopic Optical Coherence Tomography for Clinical Gastroenterology

    Directory of Open Access Journals (Sweden)

    Tsung-Han Tsai

    2014-05-01

    Full Text Available Optical coherence tomography (OCT is a real-time optical imaging technique that is similar in principle to ultrasonography, but employs light instead of sound waves and allows depth-resolved images with near-microscopic resolution. Endoscopic OCT allows the evaluation of broad-field and subsurface areas and can be used ancillary to standard endoscopy, narrow band imaging, chromoendoscopy, magnification endoscopy, and confocal endomicroscopy. This review article will provide an overview of the clinical utility of endoscopic OCT in the gastrointestinal tract and of recent achievements using state-of-the-art endoscopic 3D-OCT imaging systems.

  20. Diffuse optics for tissue monitoring and tomography

    International Nuclear Information System (INIS)

    This review describes the diffusion model for light transport in tissues and the medical applications of diffuse light. Diffuse optics is particularly useful for measurement of tissue hemodynamics, wherein quantitative assessment of oxy- and deoxy-hemoglobin concentrations and blood flow are desired. The theoretical basis for near-infrared or diffuse optical spectroscopy is developed, and the basic elements of diffuse optical tomography are outlined. We also discuss diffuse correlation spectroscopy, a technique whereby temporal correlation functions of diffusing light are transported through tissue and are used to measure blood flow. Essential instrumentation is described, and representative brain and breast functional imaging and monitoring results illustrate the workings of these new tissue diagnostics.

  1. Diffuse optics for tissue monitoring and tomography

    Science.gov (United States)

    Durduran, T.; Choe, R.; Baker, W. B.; Yodh, A. G.

    2010-07-01

    This review describes the diffusion model for light transport in tissues and the medical applications of diffuse light. Diffuse optics is particularly useful for measurement of tissue hemodynamics, wherein quantitative assessment of oxy- and deoxy-hemoglobin concentrations and blood flow are desired. The theoretical basis for near-infrared or diffuse optical spectroscopy is developed, and the basic elements of diffuse optical tomography are outlined. We also discuss diffuse correlation spectroscopy, a technique whereby temporal correlation functions of diffusing light are transported through tissue and are used to measure blood flow. Essential instrumentation is described, and representative brain and breast functional imaging and monitoring results illustrate the workings of these new tissue diagnostics.

  2. Blood oxygenation monitoring by diffuse optical tomography

    International Nuclear Information System (INIS)

    Diffuse optical tomography (DOT) makes it possible to reconstruct, in two or three dimensions, the internal structure of the biological tissues based on the distribution of the absorption coefficient and the reduced scattering coefficient, using optical measurements at multiple source - detector positions on the tissue surface. The measurement of the light intensity transmitted through the tissue can be also used to compute the haemoglobin and oxyhaemoglobin concentrations, measuring the selective absorption of the main blood chromophores by near infrared spectroscopy (NIRS). The spectral selectivity of the system and the evaluation of the blood volume and blood oxygenation (BV and OXY distributions), together with the reconstruction of the inner structure of the tissue, can improve the accuracy of early cancer diagnosis, based on the tissue angiogenesis characterisation. (application of lasers and laser-optical methods in life sciences)

  3. Fast Optical Transillumination Tomography with Large-Size Projection Acquisition

    OpenAIRE

    Huang, Hsuan-ming; Xia, Jinjun; Haidekker, Mark A.

    2008-01-01

    Techniques such as optical coherence tomography and diffuse optical tomography have been shown to effectively image highly scattering samples such as tissue. An additional modality has received much less attention: Optical transillumination tomography (OT), a modality that promises very high acquisition speed for volumetric scans. With the motivation to image tissue-engineered blood vessels for possible biomechanical testing, we have developed a fast OT device using a collimated, non-coherent...

  4. Radiotherapy dosimetry assessment with optical projection tomography

    Science.gov (United States)

    Zacharakis, Giannis; Papadakis, Antonios; Zacharopoulou, Fotini; Garofalakis, Anikitos; Maris, Thomas; Ripoll, Jorge

    2007-07-01

    Recent advances in radiotherapy have created the need to develop novel methods for the accurate, three-dimensional assessment of the applied radiation dose during specific radiotherapy plans. Here we present a study based on the use of polymer gel dosimeters in combination with a novel Optical Projection Tomography system, which allows the association of optical properties, namely the attenuation coefficient, to the irradiation dose. Polymer gel dosimeters are polymerized after X-ray irradiation via free radical production during water radiolysis resulting to increased optical opacity as well as change of the nuclear magnetic resonance relaxation times, thus making it possible to study them with both optical and MRI techniques. The optical tomographic system employs a sensitive CCD camera, a rotation stage allowing full 360 degrees rotation and a homogeneous white light source transilluminating the samples. This setup allows the calculation of the optical attenuation coefficient which can then be directly related to the applied radiotherapy dose, as well as the definition of the surface of the sample in space. The experimental procedure involves the recording of transillumination images of the polymer samples in steps of 1 degree to get the desired resolution. Data analysis is performed by back propagating the photons using an inverse Radon transform resulting to the reconstruction of three dimensional images of the attenuation coefficient or equivalently the dose distribution. The sensitivity and dynamic range offered by the technique covers the range of radiotherapy doses in modern clinical practice and are compared with the corresponding achieved with MRI.

  5. Holoscopy--holographic optical coherence tomography.

    Science.gov (United States)

    Hillmann, Dierck; Lührs, Christian; Bonin, Tim; Koch, Peter; Hüttmann, Gereon

    2011-07-01

    Scanning optical coherence tomography (OCT) is limited in sensitivity and resolution by the restricted focal depth of the confocal detection scheme. Holoscopy, a combination of holography and Fourier-domain full-field OCT, is proposed as a way to detect photons from all depths of a sample volume simultaneously with uniform sensitivity and lateral resolution, even at high NAs. By using the scalar diffraction theory, as frequently applied in digital holographic imaging, we fully reconstruct the object field with depth-invariant imaging quality. In vivo imaging of human skin is demonstrated with an image quality comparable to conventionally scanned OCT. PMID:21725421

  6. MEMS scanning micromirror for optical coherence tomography.

    Science.gov (United States)

    Strathman, Matthew; Liu, Yunbo; Keeler, Ethan G; Song, Mingli; Baran, Utku; Xi, Jiefeng; Sun, Ming-Ting; Wang, Ruikang; Li, Xingde; Lin, Lih Y

    2015-01-01

    This paper describes an endoscopic-inspired imaging system employing a micro-electromechanical system (MEMS) micromirror scanner to achieve beam scanning for optical coherence tomography (OCT) imaging. Miniaturization of a scanning mirror using MEMS technology can allow a fully functional imaging probe to be contained in a package sufficiently small for utilization in a working channel of a standard gastroesophageal endoscope. This work employs advanced image processing techniques to enhance the images acquired using the MEMS scanner to correct non-idealities in mirror performance. The experimental results demonstrate the effectiveness of the proposed technique. PMID:25657887

  7. On uniqueness in diffuse optical tomography

    International Nuclear Information System (INIS)

    A prominent result of Arridge and Lionheart (1998 Opt. Lett. 23 882–4) demonstrates that it is in general not possible to simultaneously recover both the diffusion (aka scattering) and the absorption coefficient in steady-state (dc) diffusion-based optical tomography. In this work we show that it suffices to restrict ourselves to piecewise constant diffusion and piecewise analytic absorption coefficients to regain uniqueness. Under this condition both parameters can simultaneously be determined from complete measurement data on an arbitrarily small part of the boundary

  8. Phase-Conjugate Optical Coherence Tomography

    OpenAIRE

    Erkmen, Baris I.; Shapiro, Jeffrey H.

    2009-01-01

    Quantum optical coherence tomography (Q-OCT) offers a factor-of-two 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 non-classical nature of the biphoton state employed in the former, as opposed to the classical state used in the latter. Phase-conjugate OCT (PC-OCT), introduced here, shows that non-classical light is not necessary to reap Q-OCT's a...

  9. Cartilage thickness measurements from optical coherence tomography

    Science.gov (United States)

    Rogowska, Jadwiga; Bryant, Clifford M.; Brezinski, Mark E.

    2003-02-01

    We describe a new semiautomatic image processing method for detecting the cartilage boundaries in optical coherence tomography (OCT). In particular, we focus on rabbit cartilage since this is an important animal model for testing both chondroprotective agents and cartilage repair techniques. The novel boundary-detection system presented here consists of (1) an adaptive filtering technique for image enhancement and speckle reduction, (2) edge detection, and (3) edge linking by graph searching. The procedure requires several steps and can be automated. The quantitative measurements of cartilage thickness on OCT images correlated well with measurements from histology.

  10. Improved image-forming optics for transmission optical projection tomography

    Science.gov (United States)

    Wang, Yi; Wang, Ruikang

    2007-02-01

    We demonstrate an improved image-forming optics for transmission optical projection tomography (TOPT), with which the parallel integral throughout an object can be obtained. This is performed by introducing a shutter with an appropriate diameter at the back focus of the objective lens. We evaluate and compare the performances of the improved and the conventional TOPT systems with different parameters to obtain the optimal configuration. The optimal reconstruction is achieved by the improved configuration with ? =0.8° ~1.6°, and the spatial resolution reaches 25 ?m. The Optimal configuration is validated by TOPT of a phantom sample and a five days chick embryo.

  11. 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.

  12. Optical coherence tomography: Technique and applications

    DEFF Research Database (Denmark)

    Thomsen, Jakob Borup; Sander, Birgit

    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 ultrasound and a higher penetration than confocal microcopy. Functional extensions are also possible, i.e., flow, birefringence or spectroscopic measurements with high spatial resolution. In ophthalmology, OCT is accepted as a clinical standard for diagnosing and monitoring the treatment of a number 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.

  13. Optical coherence tomography - principles and applications

    International Nuclear Information System (INIS)

    There have been three basic approaches to optical tomography since the early 1980s: diffraction tomography, diffuse optical tomography and optical coherence tomography (OCT). Optical techniques are of particular importance in the medical field, because these techniques promise to be safe and cheap and, in addition, offer a therapeutic potential. Advances in OCT technology have made it possible to apply OCT in a wide variety of applications but medical applications are still dominating. Specific advantages of OCT are its high depth and transversal resolution, the fact, that its depth resolution is decoupled from transverse resolution, high probing depth in scattering media, contact-free and non-invasive operation, and the possibility to create various function dependent image contrasting methods. This report presents the principles of OCT and the state of important OCT applications. OCT synthesises cross-sectional images from a series of laterally adjacent depth-scans. At present OCT is used in three different fields of optical imaging, in macroscopic imaging of structures which can be seen by the naked eye or using weak magnifications, in microscopic imaging using magnifications up to the classical limit of microscopic resolution and in endoscopic imaging, using low and medium magnification. First, OCT techniques, like the reflectometry technique and the dual beam technique were based on time-domain low coherence interferometry depth-scans. Later, Fourier-domain techny depth-scans. Later, Fourier-domain techniques have been developed and led to new imaging schemes. Recently developed parallel OCT schemes eliminate the need for lateral scanning and, therefore, dramatically increase the imaging rate. These schemes use CCD cameras and CMOS detector arrays as photodetectors. Video-rate three-dimensional OCT pictures have been obtained. Modifying interference microscopy techniques has led to high-resolution optical coherence microscopy that achieved sub-micrometre resolution. This report is concluded with a short presentation of important OCT applications. Ophthalmology is, due to the transparent ocular structures, still the main field of OCT application. The first commercial instrument too has been introduced for ophthalmic diagnostics (Carl Zeiss Meditec AG). Advances in using near-infrared light, however, opened the path for OCT imaging in strongly scattering tissues. Today, optical in vivo biopsy is one of the most challenging fields of OCT application. High resolution, high penetration depth, and its potential for functional imaging attribute to OCT an optical biopsy quality, which can be used to assess tissue and cell function and morphology in situ. OCT can already clarify the relevant architectural tissue morphology. For many diseases, however, including cancer in its early stages, higher resolution is necessary. New broad-bandwidth light sources, like photonic crystal fibres and superfluorescent fibre sources, and new contrasting techniques, give access to new sample properties and unmatched sensitivity and resolution

  14. Resolution improvement in emission optical projection tomography

    International Nuclear Information System (INIS)

    A new imaging technique called emission optical projection tomography (eOPT), essentially an optical version of single-photon emission computed tomography (SPECT), provides molecular specificity, resolution on the order of microns to tens of microns, and large specimen coverage (? 1 cubic centimetre). It is ideally suited to gene expression studies in embryos. Reconstructed eOPT images suffer from blurring that worsens as the distance from the axis of rotation increases. This blur is caused in part by the defocusing of the lens' point-spread function, which increases with object distance from the focal plane. In this paper, we describe a frequency space filter based on the frequency-distance relationship of sinograms to deconvolve the distance-dependent point-spread function and exclude highly defocused data from the eOPT sinograms prior to reconstruction. The method is shown to reduce the volume at half-maximum of the reconstructed point-spread function to approximately 20% the original, and the volume at 10% maximum to approximately 6% the original. As an illustration, the visibility of fine details in the vasculature of a 9.5 day old mouse embryo is dramatically improved

  15. Correction of artefacts in optical projection tomography

    International Nuclear Information System (INIS)

    A new imaging technique called optical projection tomography (OPT), essentially an optical version of x-ray computed tomography (CT), provides molecular specificity, cellular resolution and larger specimen coverage (?1 cubic centimetre) than was previously possible with other imaging techniques. It is ideally suited to gene expression studies in small animals. Reconstructed OPT images demonstrate several artefacts which reduce the overall image quality. In this paper, we describe methods to prevent smear artefacts due to illumination intensity fluctuation, ring artefacts due to CCD pixel sensitivity variation and a new 'detector edge' artefact caused by non-zero background signal. We also present an automated method to align the position of the rotational axis during image reconstruction. Finally, we propose a method to eliminate bowl artefacts due to projection truncation using a lower resolution OPT scan of the same specimen. This solution also provides OPT with the ability to obtain a high-resolution reconstruction from a region of interest of a specimen that is larger than the field of view. Implementation of these corrections and modifications increases the accuracy of the OPT imaging technique and extends its capabilities to obtain higher resolution data from within a whole specimen

  16. Blood optical clearing studied by optical coherence tomography

    Science.gov (United States)

    Zhernovaya, Olga; Tuchin, Valery V.; Leahy, Martin J.

    2013-02-01

    The main limitation of optical imaging techniques for studying biological tissues is light scattering leading to decreasing of transmittance, which lowers the imaging quality. In this case, an immersion method for optical clearing of biological tissues can provide a possible solution to this problem, because the application of biocompatible clearing agents can reduce light scattering. Optical clearing represents a promising approach to increasing the imaging depth for various techniques, for example, various spectroscopy and fluorescent methods, and optical coherence tomography (OCT). We investigate the improvement of light penetration depth in blood after application of polyethylene glycol, polypropylene glycol, propylene glycol, and hemoglobin solutions using an OCT system. Influence of clearing agents on light transport in tissues and blood was also investigated in the mouse tail vein.

  17. Doppler optical coherence tomography in cardiovascular applications

    Science.gov (United States)

    Bonesi, M.; Matcher, S.; Meglinski, I.

    2010-06-01

    The study of flow dynamics in complex geometry vessels is highly important in various biomedical applications where the knowledge of the mechanic interactions between the moving fluid and the housing media plays a key role for the determination of the parameters of interest, including the effect of blood flow on the possible rupture of atherosclerotic plaques. Doppler Optical Coherence Tomography (DOCT), as a functional extension of Optical Coherence Tomography (OCT), is an optic, non-contact, noninvasive technique able to achieve detailed analysis of the flow/vessel interactions. It allows simultaneous high resolution imaging (˜10 µm typical) of the morphology and composition of the vessel and determination of the flow velocity distribution along the measured cross-section. We applied DOCT system to image high-resolution one-dimensional and multi-dimensional velocity distribution profiles of Newtonian and non-Newtonian fluids flowing in vessels with complex geometry, including Y-shaped and T-shaped vessels, vessels with aneurism, bifurcated vessels with deployed stent and scaffolds. The phantoms were built to mimic typical shapes of human blood vessels, enabling preliminary analysis of the interaction between flow dynamics and the (complex) geometry of the vessels and also to map the related velocity profiles at several inlet volume flow rates. Feasibility studies for quantitative observation of the turbulence of flows arising within the complex geometry vessels are discussed. In addition, DOCT technique was also applied for monitoring cerebral mouse blood flow in vivo. Two-dimensional DOCT images of complex flow velocity profiles in blood vessel phantoms and in vivo sub-cranial mouse blood flow velocities distributions are presented.

  18. Doppler optical coherence tomography in cardiovascular physiology

    Science.gov (United States)

    Bonesi, M.; Meglinski, I.; Matcher, S.

    2008-09-01

    The study of flow dynamics in complex geometry vessels is highly important in many biomedical applications where the knowledge of the mechanic interactions between the moving fluid and the housing media plays a key role for the determination of the parameters of interest, including the effect of blood flow on the possible rupture of atherosclerotic plaques. Doppler Optical Coherence Tomography (DOCT), as a functional extension of Optical Coherence Tomography (OCT), is an optic, non-contact, non-invasive technique able to achieve detailed analysis of the flow/vessel interactions. It allows simultaneous high resolution imaging (10 ?m typical) of the morphology and composition of the vessel and determination of the flow velocity distribution along the measured cross-section. We applied DOCT system to image high-resolution one-dimensional and multi-dimensional velocity distribution profiles of Newtonian and non-Newtonian fluids flowing in vessels with complex geometry, including Y-shaped and T-shaped vessels, vessels with aneurism, bifurcated vessels with deployed stent and scaffolds. The phantoms were built to mimic typical shapes of human blood vessels, enabling preliminary analysis of the interaction between flow dynamics and the (complex) geometry of the vessels and also to map the related velocity profiles at several inlet volume flow rates. Feasibility studies for quantitative observation of the turbulence of flows arising within the complex geometry vessels are discussed. In addition, DOCT technique was also applied for monitoring cerebral mouse blood flow in vivo. Two-dimensional DOCT images of complex flow velocity profiles in blood vessel phantoms and in vivo sub-cranial mouse blood flow velocities distributions are presented.

  19. 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

  20. Optical coherence tomography findings in optic disk melanocytoma

    Directory of Open Access Journals (Sweden)

    Ekrem Kad?o?lu

    2011-06-01

    Full Text Available A 49 years old male patient admitted to hospital with difficulty in reading. Distant visual acuity, anterior segment examination, and intraocular pressure measurements were normal in his both eyes. The fundus examination was normal in his right eye but in the left eye a pigmented lesion overlying and surrounding the optic disk was detected. Visual field examination (HFA II version 740 Humphrey Instruments, Inc SanLeandro, CA, Central 30-2 Threshold Test was unremarkable in his right eye but an enlarged blind spot was detected in his left eye. Optical coherence tomography (OCT scans showed high reflectance layer with optical shadowing behind it. OCT is a useful device in describing the actual size of melanocytoma and its follow up. OCT has a role to find out associated subretinal fluid, cystoid retinal edema, retinal traction and epiretinal membrane. We are presenting this case to emphasize the OCT findings of melanocytoma.

  1. Nonlinear inversion schemes for fluorescence optical tomography.

    Science.gov (United States)

    Freiberger, Manuel; Egger, Herbert; Scharfetter, Hermann

    2010-11-01

    Fluorescence optical tomography is a non-invasive imaging modality that employs the absorption and re-emission of light by fluorescent dyes. The aim is to reconstruct the fluorophore distribution in a body from measurements of light intensities at the boundary. Due to the diffusive nature of light propagation in tissue, fluorescence tomography is a nonlinear and severely ill-posed problem, and some sort of regularization is required for a stable solution. In this paper we investigate reconstruction methods based on Tikhonov regularization with nonlinear penalty terms, namely total-variation regularization and a levelset-type method using a nonlinear parameterization of the unknown function. Moreover, we use the full threedimensional nonlinear forward model, which arises from the governing system of partial differential equations. We discuss the numerical realization of the regularization schemes by Newtontype iterations, present some details of the discretization by finite element methods, and outline the efficient implementation of sensitivity systems via adjoint methods. As we will demonstrate in numerical tests, the proposed nonlinear methods provide better reconstructions than standard methods based on linearized forward models and linear penalty terms. We will additionally illustrate, that the careful discretization of the methods derived on the continuous level allows to obtain reliable, mesh independent reconstruction algorithms. PMID:20562032

  2. Diffuse Optical Tomography for Brain Imaging: Theory

    Science.gov (United States)

    Yuan, Zhen; Jiang, Huabei

    Diffuse optical tomography (DOT) is a noninvasive, nonionizing, and inexpensive imaging technique that uses near-infrared light to probe tissue optical properties. Regional variations in oxy- and deoxy-hemoglobin concentrations as well as blood flow and oxygen consumption can be imaged by monitoring spatiotemporal variations in the absorption spectra. For brain imaging, this provides DOT unique abilities to directly measure the hemodynamic, metabolic, and neuronal responses to cells (neurons), and tissue and organ activations with high temporal resolution and good tissue penetration. DOT can be used as a stand-alone modality or can be integrated with other imaging modalities such as fMRI/MRI, PET/CT, and EEG/MEG in studying neurophysiology and pathology. This book chapter serves as an introduction to the basic theory and principles of DOT for neuroimaging. It covers the major aspects of advances in neural optical imaging including mathematics, physics, chemistry, reconstruction algorithm, instrumentation, image-guided spectroscopy, neurovascular and neurometabolic coupling, and clinical applications.

  3. Three-Dimensional Optical Coherence Tomography

    Science.gov (United States)

    Gutin, Mikhail; Wang, Xu-Ming; Gutin, Olga

    2009-01-01

    Three-dimensional (3D) optical coherence tomography (OCT) is an advanced method of noninvasive infrared imaging of tissues in depth. Heretofore, commercial OCT systems for 3D imaging have been designed principally for external ophthalmological examination. As explained below, such systems have been based on a one-dimensional OCT principle, and in the operation of such a system, 3D imaging is accomplished partly by means of a combination of electronic scanning along the optical (Z) axis and mechanical scanning along the two axes (X and Y) orthogonal to the optical axis. In 3D OCT, 3D imaging involves a form of electronic scanning (without mechanical scanning) along all three axes. Consequently, the need for mechanical adjustment is minimal and the mechanism used to position the OCT probe can be correspondingly more compact. A 3D OCT system also includes a probe of improved design and utilizes advanced signal- processing techniques. Improvements in performance over prior OCT systems include finer resolution, greater speed, and greater depth of field.

  4. Endoscopic applications of optical coherence tomography

    Science.gov (United States)

    Feldchtein, Felix I.; Gelikonov, G. V.; Gelikonov, V. M.; Kuranov, R. V.; Sergeev, Alexander M.; Gladkova, N.; Shakhov, A. V.; Shakhova, N. M.; Snopova, L. B.; Terent'eva, A. B.; Zagainova, E. V.; Chumakov, Yu P.; Kuznetzova, I. A.

    1998-09-01

    We report results of application of our endoscopic optical coherence tomography (EOCT) system in clinical experiments to image human internal organs. Based on the experience of studying more than 100 patients, we make first general conclusions on the place and capabilities of this method in diagnosing human mucous membranes. It is demonstrated that EOCT can serve for several clinical purposes such as performing directed biopsy, monitoring functional states of human body, guiding surgical and other treatments and monitoring post-operative recovery processes. We show that applications of OCT are more informative in the case of internal organs covered by epithelium separated from underlying stroma by a smooth basal membrane and therefore concentrate on the results of the EOCT study of three internal organs, namely of larynx, bladder, and uterine cervix. Finally, we report first examination of internal organs in abdomen with the use of laparoscopic OCT.

  5. Optical coherence tomography examination of hair

    Science.gov (United States)

    Gong, Wei; Huang, Zheng; Xu, Jianshu; Yang, Hongqin; Li, Hui; Xie, Shusen

    2014-09-01

    Human hair is a keratinous tissue composed mostly of flexible keratin, which can form a complex architecture consisting of distinct compartments or units (e.g. hair bulb, inner root sheath, shaft). Variations in hair shaft morphology can reflect ethnical diversity, but may also indicate internal diseases, nutritional deficiency, or hair and scalp disorders. Hair shaft abnormalities in cross section and diameter, as well as ultramorphological characterization and follicle shapes, might be visualized non-invasively by high-speed 2D and 3D optical coherence tomography (OCT). In this study, swept source OCT (ThorLabs) was used to examine human hair. Preliminary results showed that the high-speed OCT was a suitable and promising tool for non-invasive analysis of hair conditions.

  6. Phase-conjugate optical coherence tomography

    International Nuclear Information System (INIS)

    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

  7. Phase-conjugate optical coherence tomography

    CERN Document Server

    Erkmen, B I; Erkmen, Baris I.; Shapiro, Jeffrey H.

    2006-01-01

    Quantum optical coherence tomography (Q-OCT) offers a factor-of-two 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 non-classical nature of the biphoton state employed in the former, as opposed to the classical state used in the latter. Phase-conjugate OCT (PC-OCT), introduced here, shows that non-classical 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.

  8. Parameter and structure reconstruction in optical tomography

    International Nuclear Information System (INIS)

    Many reconstruction problems in optical tomography, such as the imaging of haematoma in the brain, or breast tumour screening, require the detection and localisation of well-defined objects on a homogeneous or weakly varying background. A conventional parameter identification approach is to represent the image in a finite dimensional set of basis functions and to find the coefficients of this set using an optimisation strategy. Shape-based reconstruction techniques on the other hand, seek to find the boundaries of objects and possibly a representation of the interior either as constant or slowly varying functions. In this paper we compare both explicit and implicit shape reconstruction methods for the simultaneous recovery of absorption and diffusion inclusions in a three-dimensional scattering medium. Images reconstructed from simulated frequency-domain boundary measurements are compared to a voxel-based conjugate gradient method. The results demonstrate the feasibility of the shape based methods.

  9. Fundamental study on diffuse reflective optical tomography

    International Nuclear Information System (INIS)

    We report a simulation study on diffuse reflective optical computed tomography, in which continuous-wave sources and detectors are placed on the plane surface of a semi-infinite body. We adopted a simple Tikhonov regularization in the inverse problem and demonstrated the feasibility of three-dimensional reconstruction of the absorption coefficient change. The spatial resolution of the reconstructed image was shown to be degrading markedly with the depth. The regularization parameter should be chosen appropriately considering the trade-off between the reconstructed image noise and the spatial resolution. We analysed the dependence of the spatial resolution of the reconstructed image on the regularization parameter and the depth, and also the behaviour of the reconstructed image noise on the regularization parameter and the depth

  10. Hyperspectral image reconstruction for diffuse optical tomography.

    Science.gov (United States)

    Larusson, Fridrik; Fantini, Sergio; Miller, Eric L

    2011-01-01

    We explore the development and performance of algorithms for hyperspectral diffuse optical tomography (DOT) for which data from hundreds of wavelengths are collected and used to determine the concentration distribution of chromophores in the medium under investigation. An efficient method is detailed for forming the images using iterative algorithms applied to a linearized Born approximation model assuming the scattering coefficient is spatially constant and known. The L-surface framework is employed to select optimal regularization parameters for the inverse problem. We report image reconstructions using 126 wavelengths with estimation error in simulations as low as 0.05 and mean square error of experimental data of 0.18 and 0.29 for ink and dye concentrations, respectively, an improvement over reconstructions using fewer specifically chosen wavelengths. PMID:21483616

  11. Improving diffuse optical tomography with structural a priori from fluorescence diffuse optical tomography

    Science.gov (United States)

    Ma, Wenjuan; Gao, Feng; Duan, Linjing; Zhu, Qingzhen; Wang, Xin; Zhang, Wei; Wu, Linhui; Yi, Xi; Zhao, Huijuan

    2012-03-01

    We obtain absorption and scattering reconstructed images by incorporating a priori information of target location obtained from fluorescence diffuse optical tomography (FDOT) into the diffuse optical tomography (DOT). The main disadvantage of DOT lies in the low spatial resolution resulting from highly scattering nature of tissue in the near-infrared (NIR), but one can use it to monitor hemoglobin concentration and oxygen saturation simultaneously, as well as several other cheomphores such as water, lipids, and cytochrome-c-oxidase. Up to date, extensive effort has been made to integrate DOT with other imaging modalities such as MRI, CT, to obtain accurate optical property maps of the tissue. However, the experimental apparatus is intricate. In this study, DOT image reconstruction algorithm that incorporates a prior structural information provided by FDOT is investigated in an attempt to optimize recovery of a simulated optical property distribution. By use of a specifically designed multi-channel time-correlated single photon counting system, the proposed scheme in a transmission mode is experimentally validated to achieve simultaneous reconstruction of the fluorescent yield, lifetime, absorption and scattering coefficient. The experimental results demonstrate that the quantitative recovery of the tumor optical properties has doubled and the spatial resolution improves as well by applying the new improved method.

  12. EDITORIAL: Optical tomography and digital holography

    Science.gov (United States)

    Coupland, Jeremy; Lobera, Julia

    2008-07-01

    The articles in this special feature in Measurement Science and Technology concern exciting new developments in the field of digital holography—the process of electronically recording and numerically reconstructing an optical field [1]. Making use of the enormous advances in digital imaging and computer technology, digital holography is presented in a range of applications from fluid flow measurement and structural analysis to medical imaging. The science of digital holography rests on the foundations of optical holography, on the work of Gabor in the late 1940s, and on the development of laser sources in the 1960s, which made his vision a practical reality [2]. Optical holography, however, uses a photosensitive material, both to record a latent image and subsequently to behave as a diffractive optical element with which to reconstruct the incident field. In this way display holograms, using silver halide materials for example, can produce life-size images that are virtually indistinguishable from the object itself [3]. Digital holography, in contrast, separates the steps of recording and reconstruction, and the final image is most often in the form of a 3D computer model. Of course, television cameras have been used from the beginnings of holography to record interferometric images. However, the huge disparity between the resolution of holographic recording materials (more than 3000 cycles/mm) and television cameras (around 50 cycles/mm) was raised as a major concern by early researchers. TV holography, as it was sometimes called, generally recorded low numerical aperture (NA) holograms producing images with characteristically large speckle and was therefore more often referred to as electronic speckle pattern interferomery (ESPI) [4]. It is possible, however, to record large NA holograms on a sensor with restricted resolution by using an objective lens or a diverging reference wave [5]. This is generally referred to as digital holographic microscopy (DHM) since 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 terms the papers we present describe closely related holographic techniques that address applicat

  13. Mid-infrared optical coherence tomography.

    Science.gov (United States)

    Colley, Christopher S; Hebden, Jeremy C; Delpy, David T; Cambrey, Alison D; Brown, Robert A; Zibik, Evgeny A; Ng, Wing H; Wilson, Luke R; Cockburn, John W

    2007-12-01

    A time domain optical coherence tomography (OCT) system is described that uses mid-infrared light (6-8 microm). To the best of our knowledge, this is the first OCT system that operates in the mid-infrared spectral region. It has been designed to characterize bioengineered tissues in terms of their structure and biochemical composition. The system is based upon a free-space Michelson interferometer with a germanium beam splitter and a liquid nitrogen cooled HgCdTe detector. A key component of this work has been the development of a broadband quantum cascade laser source (InGaAs/AlInAs containing 11 different active regions of the three well vertical transition type) that emits continuously over the 6-8 microm wavelength range. This wavelength range corresponds to the so called "mid-infrared fingerprint region" which exhibits well-defined absorption bands that are specifically attributable to the absorbing molecules. Therefore, this technology provides an opportunity for optical coherence molecular imaging without the need for molecular contrast agents. Preliminary measurements are presented. PMID:18163721

  14. Ultrasound-Mediated Biophotonic Imaging: A Review of Acousto-Optical Tomography and Photo-Acoustic Tomography

    OpenAIRE

    Wang, Lihong V.

    2004-01-01

    This article reviews two types of ultrasound-mediated biophotonic imaging–acousto-optical tomography (AOT, also called ultrasound-modulated optical tomography) and photo-acoustic tomography (PAT, also called opto-acoustic or thermo-acoustic tomography)–both of which are based on non-ionizing optical and ultrasonic waves. The goal of these technologies is to combine the contrast advantage of the optical properties and the resolution advantage of ultrasound. In these two technologies, the i...

  15. Photoacoustic tomography: Ultrasonically beating optical diffusion and diffraction

    Science.gov (United States)

    Wang, Lihong

    2014-03-01

    A decade of research has pushed photoacoustic computed tomography to the forefront of molecular-level imaging, notes SPIE Fellow Lihong Wang (Washington University, St. Louis) in his plenary talk, "Photoacoustic Tomography: Ultrasonically Beating Optical Diffusion and Diffraction." Modern optical microscopy has resolution and diffraction limitations. But noninvasive functional photoacoustic computed tomography has overcome this limit, offering deep penetration with optical contrast and ultrasonic resolution of 1 cm depth or more -- up to 7 cm of penetration in some cases, such as evaluating sentinel lymph nodes for breast cancer staging. This opens up applications in whole body imaging, brain function, oxygen saturation, label-free cell analysis, and noninvasive cancer biopsies.

  16. Multi-Scale Optical Coherence Tomography Imaging

    Science.gov (United States)

    Oliveira, Michael Christopher

    An optical modality capable of quantitative, label-free, high-speed and high-resolution imaging across spatiotemporal scales coupled with sophisticated software for image reconstruction and quantitative analyses would be of great utility to scientists and engineers in the medical and life sciences fields. Currently, a combination of optical imaging techniques and software packages are needed to address the list of capabilities described previously. Optical coherence tomography is an optical imaging technique based on low coherence interferometry capable of measuring light backscattered from the sample at micrometer-level resolutions over millimeter-level penetration depths in biological tissue. Phase-sensitive extensions of OCT enable the functional assessment of biological tissue samples as well as the structural examination of samples down to the single-cell level. This dissertation describes the development and application of high-speed real-time multi-functional spectral-domain OCT (MF-SD-OCT) for structural and functional examination of biological samples across spatiotemporal scales. A discussion of the development of a GPU-accelerated high-speed MF-SD-OCT imaging system accompanied by demonstrations of the performance enhancements due to the GPU are presented initially. Next, the development of MF-SD-OCT-based quantitative methods for the structural and functional assessment and characterization and classification of biological tissue samples is discussed. The utility of these methods is demonstrated through structural, functional and optical characterization and classification of peripheral nerve and muscle tissue. The dissertation concludes with a discussion of the improvements made to spectral-domain optical coherence phase microscopy (SD-OCPM) to enable dynamic live cell imaging and the application of dynamic live cell SD-OCPM for morphological visualization of cheek epithelial cells and examination of functionally stimulated morphological changes in neurons. The work described in this dissertation demonstrates the versatility of OCT imaging technology to perform quantitative, label-free, high-speed and high-resolution imaging across spatiotemporal scales, enabling the examination of native dynamic tissue and cellular physiology.

  17. Optical coherence tomography of the eye

    Science.gov (United States)

    Hee, Michael Richard

    1997-10-01

    Optical Coherence Tomography (OCT) is a new technique for high-resolution, cross-sectional imaging of tissue in which the time-of-flight delay of light reflected from internal tissue structures is resolved with high precision using interferometry. Tomographic images are obtained which are analogous to those provided by ultrasound except that image contrast relies on differences in optical rather than acoustic properties of tissue. The use of light rather than sound enables higher resolution (10 ?m) and non-contact imaging. A clinically viable high-sensitivity, fiber-optic based OCT instrument has been constructed based on engineering principles derived from optical communication theory. Computer algorithms have also been developed for quantitative image analysis and restoration. OCT has been used to image patients with a variety of ocular diseases. In patients with macular pathology, OCT images have been correlated with conventional clinical examination and fluorescein angiography. Optical coherence tomograms are effective in staging macular holes, evaluating the vitreoretinal interface in eyes at risk for a macular hole, and providing a structural assessment of macular hole surgery. In eyes with central serous chorioretinopathy, OCT can evaluate sensory retinal separations undetected at the slit-lamp. Serial OCT images of macular edema are able to track both the progression of macular thickening and the resolution of macular edema following laser photocoagulation. In patients with diabetic retinopathy, measurements of macular thickness correlate with visual acuity and OCT is more sensitive to small changes in retinal thickness than slit-lamp biomicroscopy. OCT may provide a novel method of defining occult choroidal neovascular membranes in patients with age-related macular degeneration. OCT can also profile the thickness of the retinal nerve fiber layer with high resolution which is potentially important for the objective assessment of early glaucoma progression. OCT images have been correlated with visual field performance and optic nerve appearance in a cross- section of patients with various stages of glaucoma. These studies suggest that OCT has the potential to become an important diagnostic tool for the practicing ophthalmologist. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253-1690.)

  18. Optical coherence tomography imaging in uveitis.

    Science.gov (United States)

    Onal, Sumru; Tugal-Tutkun, Ilknur; Neri, Piergiorgio; P Herbort, Carl

    2014-04-01

    Optical coherence tomography (OCT) is a non-contact noninvasive technique that allows in vivo imaging of the retina, choroid, optic nerve head, retinal nerve fiber layer, and the anterior structures of the eye. It was introduced into clinical practice two decades ago. Advances in OCT technology have been achieved by searching ultra-high-resolution OCT, adaptive optics OCT, eye-tracking OCT, and changes in signal detection technique from time-domain (TD) to spectral-domain (SD) detection. Today, SD OCT has become a part of routine uveitis practice. Apart from its diagnostic value in uveitis, OCT has enabled objective assessment of treatment response and provided predictive value for visual recovery and prognosis of uveitic entities. It is the standard diagnostic technique in the detection, monitoring of treatment, and determination of prognosis in uveitic macular edema as well as other inflammatory macular pathologies, including epiretinal membrane formation, vitreomacular traction, foveal atrophy, and lamellar/full-thickness macular holes. OCT has also shed light on the pathophysiology of several posterior uveitic entities. SD OCT has enabled visualization of four lines in the sensory retina which represent the external limiting membrane, the photoreceptor inner and outer segment junction, the photoreceptor outer segment and the retina pigment epithelium junction, and the retina pigment epithelium-choriocapillaris complex. Thus, we have gained substantial information about the pathologic and structural changes in uveitic conditions with primary or secondary outer retinal involvement. SD OCT has also provided invaluable information on the inner retinal and the vitreoretinal interface changes in uveitic conditions. With the introduction of enhanced depth imaging, visualization of the choroid and choriocapillaries has become possible. Therefore, OCT has become an indispensible ancillary test in the diagnosis and management of inflammatory diseases involving the retina and/or the choroid. As OCT technology continues to develop further it will provide new insights into the retinal and choroidal structure and the pathogenesis of posterior uveitic entities. PMID:23835664

  19. Airway Wall Thickness Assessed Using Computed Tomography and Optical Coherence Tomography

    OpenAIRE

    Coxson, Harvey O.; Quiney, Brendan; Sin, Don D.; Xing, Li; Mcwilliams, Annette M.; Mayo, John R.; Lam, Stephen

    2008-01-01

    Rationale: Computed tomography (CT) has been shown to reliably measure the airway wall dimensions of medium to large airways. Optical coherence tomography (OCT) is a promising new micron-scale resolution imaging technique that can image small airways 2 mm in diameter or less.

  20. Optical phase space distributions for coherence tomography

    Science.gov (United States)

    Wax, Adam Perry

    1999-11-01

    This thesis introduces optical phase space distributions, i.e., the joint position and momentum distribution of a light field. These distributions provide a new conceptual framework for the study of light propagation in multiple scattering media. Since light is predominantly scattered rather than absorbed in many biological tissues improving the understanding of light transport in a multiple scattering medium will impact current biomedical imaging techniques such as coherence tomography. A method for directly measuring optical phase space distributions using a novel heterodyne imaging scheme is developed. It is shown that the detected voltage is given as the convolution of the Wigner distribution of the light field of interest with that of a reference field when measuring the mean square heterodyne beat signal. It is further shown using Fourier optics theoretical methods that the center position and momentum of the reference field in the heterodyne scheme can be scanned by translating optical elements. Thus, the optical phase space distribution is mapped out in position and momentum as a smoothed Wigner distribution with resolution determined by the spatial width and diffraction angle of the reference field. In addition, implementation of the heterodyne scheme using low coherence length light permits selection of the path length of detected photons, effectively giving timing resolution. Wigner distributions are shown to obey rigorous transport equations which are derived from the underlying wave equations. The properties of Wigner distributions are illustrated using measured optical phase space distributions for Gaussian beams from a coherent source. A method of coherence characterization is developed that recovers the parameters of the Gaussian Schell-model. This method is applied to characterize the light sources used in the scattering studies presented in this thesis. Light scattering is investigated in three experiments. Coherent light from a helium neon laser is used to explore the field transmitted through a turbid medium consisting of 5.7 ?m polystyrene spheres in a water- glycerol mixture. The narrow diffractive pedestal is seen to attenuate more slowly than the ballistic light as the concentration of scatterers is increased. The data are in excellent agreement with a theoretical model that explains the behavior of the pedestal by including multiple diffractive scattering and treating large angle scattering as a loss. Light from broadband superluminescent diodes is used to explore the propagation of low coherence length light in multiple scattering media. Optical phase space distributions are presented for the light transmitted through varying concentrations of polystyrene spheres for different photon path lengths. It is shown that narrow momentum distributions are obtained for path lengths slightly longer than those of ballistic light. It is believed that this light can be used for biomedical optical imaging. The final study presented in this thesis examines low coherence length light which has been backscattered by a turbid medium. Optical phase space distributions are presented for various photon path lengths. The data are shown to agree with a theoretical model which is cast in the form of a Wigner distribution for comparison to experiment. (Abstract shortened by UMI.)

  1. Optical coherence tomography guided retreatment of photodynamic therapy

    OpenAIRE

    Krebs, I.; Binder, S.; Stolba, U.; Schmid, K.; Glittenberg, C.; Brannath, W.; Goll, A.

    2005-01-01

    Aim: To evaluate the results of a retreatment modality of photodynamic therapy (PDT) based on optical coherence tomography (OCT) and fluorescein angiography (FA). To quantify the effect of PDT with the help of measurement of the retinal thickness.

  2. Optical coherence tomography characterisation of idiopathic central serous chorioretinopathy

    OpenAIRE

    Montero, J. A.; Ruiz-moreno, J. M.

    2005-01-01

    Aim: To describe retinal findings in patients with idiopathic central serous chorioretinopathy (ICSC) as assessed by optical coherence tomography (OCT), and to compare them to fluorescein angiography (FA) findings.

  3. Varnish Thickness Determination by Spectral Optical Coherence Tomography

    Science.gov (United States)

    Gorczynska, I.; Wojtkowski, M.; Szkulmowski, M.; Bajraszewski, T.; Rouba, B.; Kowalczyk, A.; Targowski, P.

    The applicability of spectral optical coherence tomography (SOCT) for noninvasive and noncontact assessment of varnish layer thickness and structure on easel paintings is discussed. The SOCT tomograms of such objects are presented.

  4. Experimental Demonstration of Spectral Intensity Optical Coherence Tomography

    CERN Document Server

    Ryczkowski, Piotr; Friberg, Ari T; Genty, Goëry

    2015-01-01

    We demonstrate experimentally quantum-inspired, spectral-domain intensity optical coherence tomography. We show that the technique allows for both axial resolution improvement and dispersion cancellation compared to conventional optical coherence tomography. The method does not involve scanning and it works with classical light sources and standard photodetectors. The measurements are in excellent agreement with the theoretical predictions. We also propose an approach that enables the elimination of potential artifacts arising from multiple interfaces.

  5. Complex differential variance algorithm for optical coherence tomography angiography

    OpenAIRE

    Nam, Ahhyun S.; Chico-calero, Isabel; Vakoc, Benjamin J.

    2014-01-01

    We describe a complex differential variance (CDV) algorithm for optical coherence tomography based angiography. The algorithm exploits both the intensity and phase changes of optical coherence tomography (OCT) signals from flowing blood to achieve high vascular contrast, and also intrinsically reject undesirable phase signals originating from small displacement axial bulk tissue motion and instrument synchronization errors. We present this algorithm within a broader discussion of the properti...

  6. Motion contrast using optical coherence tomography

    Science.gov (United States)

    Fingler, Jeffrey Paul

    Diagnosis of ophthalmic diseases like age-related macular degeneration is very important for treatment of the disease as well as the development of future treatments. Optical coherence tomography (OCT) is an optical interference technique which can measure the three-dimensional structural information of the reflecting layers within a sample. In retinal imaging, OCT is used as the primary diagnostic tool for structural abnormalities such as retinal holes and detachments. The contrast within the images of this technique is based upon reflectivity changes from different regions of the retina. This thesis demonstrates the developments of methods used to produce additional contrast to the structural OCT images based on the tiny fluctuations of motion experienced by the mobile scatterers within a sample. Motion contrast was observed for motions smaller than 50 nm in images of a variety of samples. Initial contrast method demonstrations used Brownian motion differences to separate regions of a mobile Intralipid solution from a static agarose gel, chosen in concentration to minimize reflectivity contrast. Zebrafish embryos in the range of 3-4 days post fertilization were imaged using several motion contrast methods to determine the capabilities of identifying regions of vascular flow. Vasculature identification was demonstrated in zebrafish for blood vessels of all orientations as small as 10 microns in diameter. Mouse retinal imaging utilized the same motion contrast methods to determine the contrast capabilities for motions associated with vasculature within the retina. Improved contrast imaging techniques demonstrated comparable images to fluorescein angiography, the gold standard of retinal vascular imaging. Future studies can improve the demonstrated contrast analysis techniques and apply them towards human retinal motion contrast imaging for ophthalmic diagnostic purposes.

  7. Functional Spectral Domain Optical Coherence Tomography imaging

    Science.gov (United States)

    Bower, Bradley A.

    Spectral Domain Optical Coherence Tomography (SDOCT) is a high-speed, high resolution imaging modality capable of structural and functional characterization of tissue microstructure. SDOCT fills a niche between histology and ultrasound imaging, providing non-contact, non-invasive backscattering amplitude and phase from a sample. Due to the translucent nature of the tissue, ophthalmic imaging is an ideal space for SDOCT imaging. Structural imaging of the retina has provided new insights into ophthalmic disease. The phase component of SDOCT images remains largely underexplored, though. While Doppler SDOCT has been explored in a research setting, it has yet to gain traction in the clinic. Other, functional exploitations of the phase are possible and necessary to expand the utility of SDOCT. Spectral Domain Phase Microscopy (SDPM) is an extension of SDOCT that is capable of resolving sub-wavelength displacements within a focal volume. Application of sub-wavelength displacement measurement imaging could provide a new method for non-invasive optophysiological measurement. This body of work encompasses both hardware and software design and development for implementation of SDOCT. Structural imaging was proven in both the lab and the clinic. Coarse phase changes associated with Doppler flow frequency shifts were recorded and a study was conducted to validate Doppler measurement. Fine phase changes were explored through SDPM applications. Preliminary optophysiology data was acquired to study the potential of sub-wavelength measurements in the retina. To remove the complexity associated with in-vivo human retinal imaging, a first principles approach using isolated nerve samples was applied using standard SDPM and a depthencoded technique for measuring conduction velocity. Results from amplitude as well as both coarse and fine phase processing are presented. In-vivo optophysiology using SDPM is a promising avenue for exploration, and projects furthering or extending this body of work are discussed.

  8. Optical Coherence Tomography for Brain Imaging

    Science.gov (United States)

    Liu, Gangjun; Chen, Zhongping

    Recently, there has been growing interest in using OCT for brain imaging. A feasibility study of OCT for guiding deep brain probes has found that OCT can differentiate the white matter and gray matter because the white matter tends to have a higher peak reflectivity and steeper attenuation rate compared to gray matter. In vivo 3D visualization of the layered organization of a rat olfactory bulb with OCT has been demonstrated. OCT has been used for single myelin fiber imaging in living rodents without labeling. The refractive index in the rat somatosensory cortex has also been measured with OCT. In addition, functional extension of OCT, such as Doppler-OCT (D-OCT), polarization sensitive-OCT (PS-OCT), and phase-resolved-OCT (PR-OCT), can image and quantify physiological parameters in addition to the morphological structure image. Based on the scattering changes during neural activity, OCT has been used to measure the functional activation in neuronal tissues. PS-OCT, which combines polarization sensitive detection with OCT to determine tissue birefringence, has been used for the localization of nerve fiber bundles and the mapping of micrometer-scale fiber pathways in the brain. D-OCT, also named optical Doppler tomography (ODT), combines the Doppler principle with OCT to obtain high resolution tomographic images of moving constituents in highly scattering biological tissues. D-OCT has been successfully used to image cortical blood flow and map the blood vessel network for brain research. In this chapter, the principle and technology of OCT and D-OCT are reviewed and examples of potential applications are described.

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

    OpenAIRE

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

    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 sam...

  10. Quantum optical coherence tomography of a biological sample

    CERN Document Server

    Nasr, Magued B; Nguyen, Nam; Rong, Guoxin; Yang, Linglu; Reinhard, Bjorn M; Saleh, Bahaa E A; Teich, Malvin C

    2008-01-01

    Quantum optical coherence tomography (QOCT) makes use of an entangled-photon light source to carry out dispersion-immune axial optical sectioning. We present the first experimental QOCT images of a biological sample: an onion-skin tissue coated with gold nanoparticles. 3D images are presented in the form of 2D sections of different orientations.

  11. Born expansion and numerical implementation of diffuse optical tomography

    Science.gov (United States)

    Kwon, Kiwoon

    2013-10-01

    Diffuse Optical Tomography (DOT) is a nonlinear optimization problem to find optical coefficients using nearinfrared light. Linearized methods was used by many researchers to avoid the nonlinearity of DOT. In this paper, the nonlinearity of DOT is studied using Born expansion and some second and higher order inverse Born approximation methods is suggested.

  12. Atherosclerosis diagnostic imaging by optical spectroscopy and optical coherence tomography

    Science.gov (United States)

    Hewko, M. D.; Choo-Smith, L. P.; Ko, A. C. T.; Smith, M. S. D.; Kohlenberg, E. M.; Bock, E. R.; Leonardi, L.; Sowa, M. G.

    2006-02-01

    Atherosclerosis is traditionally viewed as a disease of uncontrolled plaque growth leading to arterial occlusion. More recently, however, occlusion of the arterial lumen is being viewed as an acute event triggered by plaque rupture and thrombosis. An atheromatous plaque becomes vulnerable to sudden activation and/or rupture when a constellation of processes are activated by various trigger mechanisms. There is growing evidence that the vulnerability (i.e. susceptibility to rupture) and thrombogenic nature of the plaque need to be taken into account in the planning and treatment of the disease. X-ray fluoroscopy and intravascular ultrasound, the current clinical diagnostic tools are not capable of the providing a complete histological picture of the plaque region. Intravascular diagnostic imaging of coronary atherosclerotic plaques by optical means to assess plaque, patient risk and assist in planning treatment strategies represents the future in angioplasty treatment by interventional cardiologists. The techniques which will enable a clinically acceptable and reliable intravascular diagnostic platform are currently being investigated and compared to the clinical standard of histology. Currently, we are investigating the use of a number of optical and imaging techniques for biochemical analysis of arterial tissue including Raman, near infrared and fluorescence spectroscopies. Biochemical imaging will provide compositional information on collagen, elastin, lipid and thrombogenic by-products as well as gauging inflammation and tissue remodeling activity levels. To complement the functional biochemical imaging, optical coherence tomography will be provide structural morphological imaging. The synergistic combination of functional and structural imagery will provide the interventional cardiologist with a complete clinical picture of the atherosclerotic plaque region. The clinician can use this diagnostic information to plan a personalized treatment procedure based on the entire clinical presentation.

  13. A 5° medial wedge reduces frontal but not saggital plane motion during jump landing in highly trained women athletes

    Directory of Open Access Journals (Sweden)

    Michael F Joseph

    2010-03-01

    Full Text Available Michael F Joseph1, Craig R Denegar1, Elaine Horn1, Bradley MacDougall1, Michael Rahl1, Jessica Sheehan1, Thomas Trojian2, Jeffery M Anderson1, James E Clark1, William J Kraemer11Department of Kinesiology, 2Department of Sports Medicine, University of Connecticut, Storrs, CT, USAAbstract: Lower extremity mechanics during landing have been linked to traumatic and nontraumatic knee injuries, particularly in women’s athletics. The effects of efforts to mitigate these risks have not been fully elucidated. We previously reported that a 5° medial wedge reduced ankle eversion and knee valgus. In the present report we further investigated the effect of a 5° medial wedge inserted in the shoes of female athletes on frontal plane hip motion, as well as ankle, knee, hip, and trunk saggital plane motion during a jump landing task. Kinematic data were obtained from 10 intercollegiate female athletes during jump landings from a 31 cm platform with and without a 5° medial wedge. Hip adduction was reduced 1.98° (95% CI 0.97–2.99° by the medial wedge but saggital plane motions were unaffected. A 5° medial wedge reduces frontal plane motion and takes the knee away from a position associated with anterior cruciate ligament injury and patellofemoral pain syndrome. Although frontal plane motion was not captured it is unlikely to have increased in a bilateral landing task. Thus, it is likely that greater muscle forces were generated in these highly trained athletes to dissipate ground reaction forces when a medial wedge was in place. Additional investigation in younger and lesser trained athletes is warranted to assess the impact of orthotic devices on knee joint mechanics.Keywords: jump landing, foot orthotic, lower extremity kinematics, knee biomechanics, knee injury

  14. Self-calibrated algorithms for diffuse optical tomography and bioluminescence tomography using relative transmission images

    OpenAIRE

    Naser, Mohamed A.; Patterson, Michael S.; Wong, John W.

    2012-01-01

    Reconstruction algorithms for diffuse optical tomography (DOT) and bioluminescence tomography (BLT) have been developed based on diffusion theory. The algorithms numerically solve the diffusion equation using the finite element method. The direct measurements of the uncalibrated light fluence rates by a camera are used for the reconstructions. The DOT is self-calibrated by using all possible pairs of transmission images obtained with external sources along with the relative val...

  15. [Basic principles of optical coherence tomography in interventional cardiology].

    Science.gov (United States)

    2013-01-01

    Optical coherence tomography (OCT) is a technique of visualizing biological tissues. This technique versus intravascular ultrasound study has high resolution. OCT has proved to be effective in interventional cardiology due to a resolution of 10 microm. As of now, there are two crucially new different OCT flow charts. One is tomography, the basis for which is a Michelson interferometer and an up-to-date tomography scanner, such as a Fourier transform spectral interferometer. This paper describes the brief history of OCT and the principle of its operation, compares two basically different technologies, and depicts the limitations of the technique when performed in different ways. PMID:25702446

  16. Ultrasound-mediated optical tomography: a review of current methods

    OpenAIRE

    Elson, Ds; Li, R.; Dunsby, C.; Eckersley, R.; Tang, M-x

    2011-01-01

    Ultrasound-mediated optical tomography (UOT) is a hybrid technique that is able to combine the high penetration depth and high spatial resolution of ultrasound imaging to overcome the limits imposed by optical scattering for deep tissue optical sensing and imaging. It has been proposed as a method to detect blood concentrations, oxygenation and metabolism at depth in tissue for the detection of vascularized tumours or the presence of absorbing or scattering contrast agents. In this paper, the...

  17. Mapping distributed brain function and networks with diffuse optical tomography

    Science.gov (United States)

    Eggebrecht, Adam T.; Ferradal, Silvina L.; Robichaux-Viehoever, Amy; Hassanpour, Mahlega S.; Dehghani, Hamid; Snyder, Abraham Z.; Hershey, Tamara; Culver, Joseph P.

    2014-06-01

    Mapping of human brain function has revolutionized systems neuroscience. However, traditional functional neuroimaging by positron emission tomography or functional magnetic resonance imaging cannot be used when applications require portability, or are contraindicated because of ionizing radiation (positron emission tomography) or implanted metal (functional magnetic resonance imaging). Optical neuroimaging offers a non-invasive alternative that is radiation free and compatible with implanted metal and electronic devices (for example, pacemakers). However, optical imaging technology has heretofore lacked the combination of spatial resolution and wide field of view sufficient to map distributed brain functions. Here, we present a high-density diffuse optical tomography imaging array that can map higher-order, distributed brain function. The system was tested by imaging four hierarchical language tasks and multiple resting-state networks including the dorsal attention and default mode networks. Finally, we imaged brain function in patients with Parkinson's disease and implanted deep brain stimulators that preclude functional magnetic resonance imaging.

  18. Optical Doppler tomography based on a field programmable gate array

    DEFF Research Database (Denmark)

    Larsen, Henning Engelbrecht; Nilsson, Ronnie Thorup

    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.

  19. Topological sensitivity analysis in fluorescence optical tomography

    International Nuclear Information System (INIS)

    Fluorescence tomography is a non-invasive imaging modality that reconstructs fluorophore distributions inside a small animal from boundary measurements of the fluorescence light. The associated inverse problem is stabilized by a priori properties or information. In this paper, cases are considered where the fluorescent inclusions are well separated from the background and have a spatially constant concentration. Under these a priori assumptions, the identification process may be formulated as a shape optimization problem, where the interface between the fluorescent inclusion and the background constitutes the unknown shape. In this paper, we focus on the computation of the so-called topological derivative for fluorescence tomography which could be used as a stand-alone tool for the reconstruction of the fluorophore distributions or as the initialization in a level-set-based method for determining the shape of the inclusions. (paper)

  20. X-ray luminescence optical tomography imaging: experimental studies.

    Science.gov (United States)

    Li, Changqing; Di, Kun; Bec, Julien; Cherry, Simon R

    2013-07-01

    We present a hybrid imaging modality, x-ray luminescence optical tomography (XLOT), in which collimated x-ray beams are used to excite phosphor-based contrast agents. Images are reconstructed from the optical signals, using the known x-ray beam location and spatial extent as priors. We demonstrate XLOT using phantom experiments with deep targets and show that the reconstructed signal varies by orthogonal projection measurements are sufficient for XLOT reconstruction. PMID:23811921

  1. Common path optical coherence tomography with fibre bundle probe

    OpenAIRE

    Han, J. -h; Liu, X.; Song, C. G.; Kang, J. U.

    2009-01-01

    A simple common path optical coherence tomography using a fibre optic bundle as a probe is demonstrated experimentally. The mechanical lateral scans are accomplished outside the specimen, proximal entrance of the fibre bundle, which eliminated the need for moving parts in the distal end of the probe. This feature allows the probe to be made submillimetre in size and easily integrated into surgical tools for intraoperative imaging. The axial and lateral resolutions of the system, and prelimina...

  2. Fluorescence lifetime optical tomography with Discontinuous Galerkin discretisation scheme

    OpenAIRE

    Soloviev, V. Y.; D Andrea, C.; Mohan, P. S.; Valentini, G.; Cubeddu, R.; Arridge, S. R.

    2010-01-01

    We develop discontinuous Galerkin framework for solving direct and inverse problems in fluorescence diffusion optical tomography in turbid media. We show the advantages and the disadvantages of this method by comparing it with previously developed framework based on the finite volume discretization. The reconstruction algorithm was used with time-gated experimental dataset acquired by imaging a highly scattering cylindrical phantom concealing small fluorescent tubes. Optical parameters, quant...

  3. Fluorescence lifetime optical tomography with Discontinuous Galerkin discretisation scheme.

    Science.gov (United States)

    Soloviev, Vadim Y; D'Andrea, Cosimo; Mohan, P Surya; Valentini, Gianluca; Cubeddu, Rinaldo; Arridge, Simon R

    2010-01-01

    We develop discontinuous Galerkin framework for solving direct and inverse problems in fluorescence diffusion optical tomography in turbid media. We show the advantages and the disadvantages of this method by comparing it with previously developed framework based on the finite volume discretization. The reconstruction algorithm was used with time-gated experimental dataset acquired by imaging a highly scattering cylindrical phantom concealing small fluorescent tubes. Optical parameters, quantum yield and lifetime were simultaneously reconstructed. Reconstruction results are presented and discussed. PMID:21258525

  4. Optical Coherence Tomography: Future Trends for Imaging in Glaucoma

    OpenAIRE

    Folio, Lindsey S.; Wollstein, Gadi; Schuman, Joel S.

    2012-01-01

    Optical coherence tomography (OCT) captures a major role in clinical assessment in eye care. Innovative hardware and software improvements in the technology would further enhance its usefulness. In this review we present several promising initiatives currently in development or early phase of assessment that we expect to have a future impact on OCT.

  5. Superresolution and Corrections to the Diffusion Approximation in Optical Tomography

    CERN Document Server

    Panasyuk, G Y; Schotland, J C; Panasyuk, George Y.; Markel, Vadim A.; Schotland, John C.

    2005-01-01

    We demonstrate that the spatial resolution of images in optical tomography is not limited to the fundamental length scale of one transport mean free path. This result is facilitated by the introduction of novel corrections to the standard integral equations of scattering theory within the diffusion approximation to the radiative transport equation.

  6. Path method for reconstructing images in fluorescence optical tomography

    International Nuclear Information System (INIS)

    A reconstruction method elaborated for the optical diffusion tomography of the internal structure of objects containing absorbing and scattering inhomogeneities is considered. The method is developed for studying objects with fluorescing inhomogeneities and can be used for imaging of distributions of artificial fluorophores whose aggregations indicate the presence of various diseases or pathological deviations. (special issue devoted to multiple radiation scattering in random media)

  7. Imaging of Breast Cancer and Epilepsy using Diffuse Optical Tomography

    Science.gov (United States)

    Jiang, Huabei

    2009-11-01

    In this talk, I will describe the fundamental principles of the emerging near-infrared diffuse optical tomography. In my laboratory this imaging technology has been developed for imaging of breast cancer, osteoarthritis, epilepsy and drug delivery/gene therapy. I will report on our most recent clinical and preclinical studies in breast cancer and epilepsy.

  8. Optical coherence tomography to monitor photodynamic therapy in pathological myopia

    OpenAIRE

    2006-01-01

    To evaluate the role of optical coherence tomography (OCT) in determining choroidal neovascularisation (CNV) activity before and after photodynamic therapy (PDT) in patients with pathological myopia. METHODS: 33 patients (33 eyes) with pathological myopia and being treated with PDT were included. Every 3 months all patients were evaluated and presence or absence of leakage on fluorescein angiography, presence of intraretinal or subretinal fluid on...

  9. RADIAL COMPUTED TOMOGRAPHY OF AIR CONTAMINANTS USING OPTICAL REMOTE SENSING

    Science.gov (United States)

    The paper describes the application of an optical remote-sensing (ORS) system to map air contaminants and locate fugitive emissions. Many ORD systems may utilize radial non-overlapping beam geometry and a computed tomography (CT) algorithm to map the concentrations in a plane. In...

  10. Analysis of Pars Plana Vitrectomy for Optic Pit–Related Maculopathy With Intraoperative Optical Coherence Tomography

    Science.gov (United States)

    Ehlers, Justis P.; Kernstine, Kendal; Farsiu, Sina; Sarin, Neeru; Maldonado, Ramiro; Toth, Cynthia A.

    2012-01-01

    Optimal management of optic pit–related maculopathy remains to be determined. The fluid source for the maculopathy also remains controversial. In this article, we present a unique surgical technique for internal drainage of the intraretinal fluid and describe the intraoperative use of spectral-domain optical coherence tomography to assist in the surgical management of this condition. Pars plana vitrectomy was performed with elevation of the posterior hyaloid. Following an air-fluid exchange, aspiration over the optic nerve pit was performed. Following aspiration, intraoperative spectral-domain optical coherence tomography demonstrated collapse of the retinoschisis, strongly suggesting a connection between the vitreous cavity and the intraretinal fluid. PMID:22084218

  11. Intravascular optical coherence tomography on a beating heart model

    Science.gov (United States)

    Lamouche, Guy; Dufour, Marc; Hewko, Mark; Vergnole, Sébastien; Gauthier, Bruno; Bisaillon, Charles-Étienne; Monchalin, Jean-Pierre; Sowa, Michael G.

    2010-07-01

    The advantages and limitations of using a beating heart model in the development of intravascular optical coherence tomography are discussed. The model fills the gap between bench experiments, performed on phantoms and excised arteries, and whole animal in-vivo preparations. The beating heart model is stable for many hours, allowing for extended measurement times and multiple imaging sessions under in-vivo conditions without the complications of maintaining whole-animal preparation. The perfusate supplying the heart with nutrients can be switched between light scattering blood to a nonscattering perfusate to allow the optical system to be optimized without the need of an efficient blood displacement strategy. Direct access to the coronary vessels means that there is no need for x-ray fluoroscopic guidance of the catheter to the heart, as is the case in whole animal preparation. The model proves to be a valuable asset in the development of our intravascular optical coherence tomography technology.

  12. Characterization of the dental pulp using optical coherence tomography

    Science.gov (United States)

    Kauffman, C. M. F.; Carvalho, M. T.; Araujo, R. E.; Freitas, A. Z.; Zezell, D. M.; Gomes, A. S. L.

    2006-02-01

    The inner structure of teeth, i.e. the root canal anatomy, is very complex. However a good knowledge of endodontic architecture is the first step towards successful endodontic treatment. Optical coherence tomography (OCT) is a powerful technique to generate images of hard and soft tissue. Its images show dependency on the optical properties of the tissue under analysis. Changes in the scattering and absorption of tissues can be observed through the OCT images. In this work, we used optical coherence tomography to perform in vitro studies of the inner structure of the first molar of albino rats (Rattus norvegicus). Focusing on the pulp chamber and in the root canal, we compare the images generated with the OCT technique to the histology. We are analyzing the feasibility of OCT to help on the diagnostic of endodontic diseases.

  13. In vivo endoscopic multi-beam optical coherence tomography

    Science.gov (United States)

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

    2010-02-01

    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 oesophagus and trachea. A good correlation between the structural multi-beam OCT images and H&E histology was achieved, demonstrating the feasibility of this high-resolution system and its potential for in vivo human endoscopic imaging.

  14. The significance of computed tomography in optic neuropathy

    International Nuclear Information System (INIS)

    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)

  15. Wavelength-encoded tomography based on optical temporal Fourier transform

    International Nuclear Information System (INIS)

    We propose and demonstrate a technique called wavelength-encoded tomography (WET) for non-invasive optical cross-sectional imaging, particularly beneficial in biological system. The WET utilizes time-lens to perform the optical Fourier transform, and the time-to-wavelength conversion generates a wavelength-encoded image of optical scattering from internal microstructures, analogous to the interferometery-based imaging such as optical coherence tomography. Optical Fourier transform, in principle, comes with twice as good axial resolution over the electrical Fourier transform, and will greatly simplify the digital signal processing after the data acquisition. As a proof-of-principle demonstration, a 150?-?m (ideally 36??m) resolution is achieved based on a 7.5-nm bandwidth swept-pump, using a conventional optical spectrum analyzer. This approach can potentially achieve up to 100-MHz or even higher frame rate with some proven ultrafast spectrum analyzer. We believe that this technique is innovative towards the next-generation ultrafast optical tomographic imaging application.

  16. Optical computed tomography liquid calibration phantom

    International Nuclear Information System (INIS)

    Fluorinated ethylene propylene tubing is investigated as a method of preparing a contrast-resolution phantom for quantitative characterization of optical CT scanners and hydrogel dosimeters. Two sizes of tubing were examined: 6 and 13 mm inner diameter with 0.75 and 0.5 mm wall thicknesses, respectively. Water solutions of carbon black, nanoparticles in micelles provided continuously adjustable absorption contrast. Cross-sectional slices from two phantoms scanned with two different optical CT scanners are presented. Reconstructions from these simple phantoms can be used to identify scanner artefacts and improve instrument design. These phantoms represent a more reproducible approach than casting ''gel fingers'' into gel phantoms for system characterization. The thinner walled tubes have fewer optical artefacts.

  17. Imaging techniques utilizing optical fibers and tomography

    Energy Technology Data Exchange (ETDEWEB)

    Wilke, M.; King, N.S.P.; Gray, N.; Johnson, D.; Esquibel, D.; Nedrow, P.; Ishiwata, S.

    1985-01-01

    Two-dimensional, time-dependent images generated by neutrons, gamma rays, and x-rays incident on fast scintillators are relayed to streak and video cameras over optical fibers. Three dimensions, two spatial and one temporal, have been reduced to two, one in space and time utilizing sampling methods permitting reconstruction of a time-dependent, two-dimensional image subsequent to data recording. The manner in which the sampling is done optimized the ability to reconstruct the image via a maximization of entropy algorithm. This method uses four linear fiber optic arrays typically 30 meters long and up to 35 elements each. A further refinement of this technique collapses the linear array information into four single fibers by wavelength multiplexing. This permits economical transmission of the data over kilometer distances to the recording equipment.

  18. Positron emission tomography and optical tissue imaging

    Science.gov (United States)

    Falen, Steven W. (Carmichael, CA); Hoefer, Richard A. (Newport News, VA); Majewski, Stanislaw (Yorktown, VA); McKisson, John (Hampton, VA); Kross, Brian (Yorktown, VA); Proffitt, James (Newport News, VA); Stolin, Alexander (Newport News, VA); Weisenberger, Andrew G. (Yorktown, VA)

    2012-05-22

    A mobile compact imaging system that combines both PET imaging and optical imaging into a single system which can be located in the operating room (OR) and provides faster feedback to determine if a tumor has been fully resected and if there are adequate surgical margins. While final confirmation is obtained from the pathology lab, such a device can reduce the total time necessary for the procedure and the number of iterations required to achieve satisfactory resection of a tumor with good margins.

  19. 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 ?m. The combination of OCT and MPT provides a synergistic optical imaging modality for early detection of skin cancer and other skin diseases.

  20. Analysis of skin lesions using laminar optical tomography

    OpenAIRE

    Muldoon, Timothy J.; Burgess, Sean A.; Chen, Brenda R.; Ratner, De?sire?e; Hillman, Elizabeth M. C.

    2012-01-01

    Evaluation of suspicious skin lesions by dermatologists is usually accomplished using white light examination and direct punch or surgical biopsy. However, these techniques can be imprecise for estimating a lesion’s margin or level of dermal invasion when planning surgical resection. Laminar optical tomography (LOT) is an imaging technique capable of acquiring depth-sensitive information within scattering tissues. Here, we explore whether LOT data can be used to predict the depth and thickn...

  1. Simulated and measured optical coherence tomography images of human enamel.

    Science.gov (United States)

    Kienle, Alwin; Schäfer, Jan

    2012-08-01

    Optical coherence tomography images of human enamel were simulated and compared to measured images. A Monte Carlo code was implemented, which considered the microstructure of enamel. The prisms, the main scattering structures of the enamel, were described by oscillating cylinders whose scattering functions were obtained by solutions of Maxwell's equations. The essential features of the measured images including the Hunter-Schreger bands could be explained by the simulations. PMID:22859147

  2. Rapid volumetric angiography of cortical microvasculature with optical coherence tomography

    OpenAIRE

    Srinivasan, Vivek J.; Jiang, James Y.; Yaseen, Mohammed A.; Radhakrishnan, Harsha; Wu, Weicheng; Barry, Scott; Cable, Alex E.; Boas, David A.

    2010-01-01

    We describe methods and algorithms for rapid volumetric imaging of cortical vasculature with optical coherence tomography (OCT). By optimizing system design, scanning protocols, and algorithms for visualization of capillary flow, comprehensive imaging of the surface pial vasculature and capillary bed is performed in approximately 12 s. By imaging during hypercapnia and comparing with simultaneous CCD imaging, the sources of contrast of OCT angiography are investigated.

  3. Monte Carlo modeling of angiographic optical coherence tomography

    OpenAIRE

    Hartinger, Alzbeta E.; Nam, Ahhyun S.; Chico-calero, Isabel; Vakoc, Benjamin J.

    2014-01-01

    Optical coherence tomography (OCT) provides both structural and angiographic imaging modes. Because of its unique capabilities, OCT-based angiography has been increasingly adopted into small animal and human subject imaging. To support the development of the signal and image processing algorithms on which OCT-based angiography depends, we describe here a Monte Carlo-based model of the imaging approach. The model supports arbitrary three-dimensional vascular network geometries and incorporates...

  4. Quantitative cerebral blood flow with Optical Coherence Tomography

    OpenAIRE

    Srinivasan, Vivek J.; Sakadz?ic?, Sava; Gorczynska, Iwona; Ruvinskaya, Svetlana; Wu, Weicheng; Fujimoto, James G.; Boas, David A.

    2010-01-01

    Absolute measurements of cerebral blood flow (CBF) are an important endpoint in studies of cerebral pathophysiology. Currently no accepted method exists for in vivo longitudinal monitoring of CBF with high resolution in rats and mice. Using three-dimensional Doppler Optical Coherence Tomography and cranial window preparations, we present methods and algorithms for regional CBF measurements in the rat cortex. Towards this end, we develop and validate a quantitative statistical model to describ...

  5. Optical coherence tomography for the quantitative study of cerebrovascular physiology

    OpenAIRE

    Srinivasan, Vivek J.; Atochin, Dmitriy N.; Radhakrishnan, Harsha; Jiang, James Y.; Ruvinskaya, Svetlana; Wu, Weicheng; Barry, Scott; Cable, Alex E.; Ayata, Cenk; Huang, Paul L.; Boas, David A.

    2011-01-01

    Doppler optical coherence tomography (DOCT) and OCT angiography are novel methods to investigate cerebrovascular physiology. In the rodent cortex, DOCT flow displays features characteristic of cerebral blood flow, including conservation along nonbranching vascular segments and at branch points. Moreover, DOCT flow values correlate with hydrogen clearance flow values when both are measured simultaneously. These data validate DOCT as a noninvasive quantitative method to measure tissue perfusion...

  6. Imaging treated brain aneurysms in vivo using optical coherence tomography

    Science.gov (United States)

    Su, Jianping; Mathews, Marlon S.; Nwagwu, Chiedozie I.; Edris, Ahmad; Nguyen, Binh V.; Heidari, Mehrzad; Linskey, Mark E.; Chen, Zhongping

    2008-02-01

    Angiography is currently used to assess post-treatment human brain aneurysm healing, which can reveal vessel shape only. Optical coherence tomography (OCT) can reveal the vessel wall structure with high resolution, which has the advantage to assess vessel healing progress. An OCT endovascular catheter was designed and in vivo patients' studies were performed. Flush effect of saline and perfluorodecalin (PFC) were studies in rabbit aorta. The initial results show that OCT is a promising technology to assess post-treatment cerebrovascular diseases.

  7. Anterior chamber angle imaging with optical coherence tomography

    OpenAIRE

    Leung, C. K-s; Weinreb, R. N.

    2011-01-01

    The technology of optical coherence tomography (OCT) has evolved rapidly from time-domain to spectral-domain and swept-source OCT over the recent years. OCT has become an important tool for assessment of the anterior chamber angle and detection of angle closure. Improvement in image resolution and scan speed of OCT has facilitated a more detailed and comprehensive analysis of the anterior chamber angle. It is now possible to examine Schwalbe's line and Schlemm's canal along with the scleral s...

  8. Intracoronary optical coherence tomography, basic theory and image acquisition techniques

    OpenAIRE

    Prati, F.; Jenkins, M. W.; Di Giorgio, A.; Rollins, A. M.

    2011-01-01

    Optical coherence tomography (OCT) imaging is showing great potential as an alternative or complementary tool to intravascular ultrasound (IVUS) for aiding in stent procedures and future diagnosis/treatment of atherosclerosis. Here, we describe the basic theory behind OCT imaging and explain important parameters such as axial resolution, lateral resolution and sensitivity. Also, we describe several image acquisition techniques that have been adopted for OCT imaging.

  9. Scalable multiplexing for parallel imaging with interleaved optical coherence tomography

    OpenAIRE

    Lee, Hee Yoon; Marvdashti, Tahereh; Duan, Lian; Khan, Saara A.; Ellerbee, Audrey K.

    2014-01-01

    We demonstrate highly parallel imaging with interleaved optical coherence tomography (iOCT) using an in-house-fabricated, air-spaced virtually-imaged phased array (VIPA). The air-spaced VIPA performs spectral encoding of the interferograms from multiple lateral points within a single sweep of the source and allows us to tune and balance several imaging parameters: number of multiplexed points, ranging depth, and sensitivity. In addition to a thorough discussion of the parameters and operating...

  10. Optical Coherence Tomography Scanning with a Handheld Vitreoretinal Micromanipulator

    OpenAIRE

    Yang, Sungwook; Balicki, Marcin; Maclachlan, Robert A.; Liu, Xuan; Kang, Jin U.; Taylor, Russell H.; Riviere, Cameron N.

    2012-01-01

    An active handheld micromanipulator has been developed that is capable of automated intraocular acquisition of B-mode and C-mode optical coherence tomography scans that are up to 4 mm wide. The manipulator is a handheld Gough-Stewart platform actuated by ultrasonic linear motors. The manipulator has been equipped with a Fourier-domain common-path intraocular OCT probe that fits within a 25-gauge needle. The paper describes the systems and techniques involved, and presents preliminary results ...

  11. The Use of Optical Coherence Tomography in Intraoperative Ophthalmic Imaging

    OpenAIRE

    Hahn, Paul; Migacz, Justin; O’connell, Rachelle; Maldonado, Ramiro S.; Izatt, Joseph A.; Toth, Cynthia A.

    2011-01-01

    Optical coherence tomography (OCT) has transformed diagnostic ophthalmic imaging but until recently has been limited to the clinic setting. The development of spectral-domain OCT (SD-OCT), with its improved speed and resolution, along with the development of a handheld OCT scanner, enabled portable imaging of patients unable to sit in a conventional tabletop scanner. This handheld SD-OCT unit has proven useful in examinations under anesthesia and, more recently, in intraoperative imaging of p...

  12. Polarization sensitive optical coherence tomography in the human eye

    OpenAIRE

    Pircher, Michael; Hitzenberger, Christoph K.; Schmidt-erfurth, Ursula

    2011-01-01

    Optical coherence tomography (OCT) has become a well established imaging tool in ophthalmology. The unprecedented depth resolution that is provided by this technique yields valuable information on different ocular tissues ranging from the anterior to the posterior eye segment. Polarization sensitive OCT (PS-OCT) extends the concept of OCT and utilizes the information that is carried by polarized light to obtain additional information on the tissue. Several structures in the eye (e.g. cornea, ...

  13. Automatic segmentation of choroidal thickness in optical coherence tomography

    OpenAIRE

    Alonso-caneiro, David; Read, Scott A.; Collins, Michael J.

    2013-01-01

    The assessment of choroidal thickness from optical coherence tomography (OCT) images of the human choroid is an important clinical and research task, since it provides valuable information regarding the eye’s normal anatomy and physiology, and changes associated with various eye diseases and the development of refractive error. Due to the time consuming and subjective nature of manual image analysis, there is a need for the development of reliable objective automated methods of image segmen...

  14. Corneal topography from spectral optical coherence tomography (sOCT)

    OpenAIRE

    Ortiz, Sergio; Siedlecki, Damian; Pe?rez Merino, Pablo; Chia, Noelia; Castro, Alberto; Szkulmowski, Maciej; Wojtkowski, Maciej; Marcos, Susana

    2011-01-01

    We present a method to obtain accurate corneal topography from a spectral optical coherence tomography (sOCT) system. The method includes calibration of the device, compensation of the fan (or field) distortion introduced by the scanning architecture, and image processing analysis for volumetric data extraction, segmentation and fitting. We present examples of three-dimensional (3-D) surface topography measurements on spherical and aspheric lenses, as well as on 10 human corneas in vivo. Resu...

  15. Diffuse optical tomography with physiological and spatial a priori constraints

    International Nuclear Information System (INIS)

    Diffuse optical tomography is a typical inverse problem plagued by ill-condition. To overcome this drawback, regularization or constraining techniques are incorporated in the inverse formulation. In this work, we investigate the enhancement in recovering functional parameters by using physiological and spatial a priori constraints. More accurate recovery of the two main functional parameters that are the blood volume and the relative saturation is demonstrated through simulations by using our method compared to actual techniques. (note)

  16. Quantitative comparison of analysis methods for spectroscopic optical coherence tomography

    OpenAIRE

    Bosschaart, Nienke; Leeuwen, Ton G.; Aalders, Maurice C. G.; Faber, Dirk J.

    2013-01-01

    Spectroscopic optical coherence tomography (sOCT) enables the mapping of chromophore concentrations and image contrast enhancement in tissue. Acquisition of depth resolved spectra by sOCT requires analysis methods with optimal spectral/spatial resolution and spectral recovery. In this article, we quantitatively compare the available methods, i.e. the short time Fourier transform (STFT), wavelet transforms, the Wigner-Ville distribution and the dual window method through simulations in tissue-...

  17. Revealing retroperitoneal liposarcoma morphology using optical coherence tomography

    Science.gov (United States)

    Carbajal, Esteban F.; Baranov, Stepan A.; Manne, Venu G. R.; Young, Eric D.; Lazar, Alexander J.; Lev, Dina C.; Pollock, Raphael E.; Larin, Kirill V.

    2011-02-01

    A new approach to distinguish normal fat, well-differentiated (WD), and dedifferentiated liposarcoma (LS) tumors is demonstrated, based on the use of optical coherence tomography (OCT). OCT images show the same structures seen with conventional histological methods. Our visual grading analysis is supported by numerical analysis of observed structures for normal fat and WDLS samples. Further development could apply the real-time and high resolution advantages of OCT for use in liposarcoma diagnosis and clinical procedures.

  18. Real-time compressive sensing spectral domain optical coherence tomography.

    Science.gov (United States)

    Xu, Daguang; Huang, Yong; Kang, Jin U

    2014-01-01

    We developed and demonstrated real-time compressive sensing (CS) spectral domain optical coherence tomography (SD-OCT) B-mode imaging at excess of 70 fps. The system was implemented using a conventional desktop computer architecture having three graphics processing units. This result shows speed gain of 459 and 112 times compared to the best CS implementations based on the MATLAB and C++, respectively, and that real-time CS SD-OCT imaging can finally be realized. PMID:24365826

  19. Subluxed traumatic cataract: optical coherence tomography findings and clinical management

    OpenAIRE

    Ae, Kuriyan; Hw, Flynn Jr; Sh, Yoo

    2012-01-01

    Ajay E Kuriyan, Harry W Flynn Jr, Sonia H YooDepartment of Ophthalmology, Bascom Palmer Eye Institute, University of Miami, Miami, FLAbstract: This case report describes the optical coherence tomography (OCT) findings and clinical management of a patient with traumatic subluxed cataract. The patient presented with a traumatic subluxed cataract and vitreous prolapse into the anterior chamber. The anterior segment OCT showed vacuoles in the anterior subcapsular regions of the crystalline lens. ...

  20. Algorithm for localized adaptive diffuse optical tomography and its application in bioluminescence tomography.

    Science.gov (United States)

    Naser, Mohamed A; Patterson, Michael S; Wong, John W

    2014-04-21

    A reconstruction algorithm for diffuse optical tomography based on diffusion theory and finite element method is described. The algorithm reconstructs the optical properties in a permissible domain or region-of-interest to reduce the number of unknowns. The algorithm can be used to reconstruct optical properties for a segmented object (where a CT-scan or MRI is available) or a non-segmented object. For the latter, an adaptive segmentation algorithm merges contiguous regions with similar optical properties thereby reducing the number of unknowns. In calculating the Jacobian matrix the algorithm uses an efficient direct method so the required time is comparable to that needed for a single forward calculation. The reconstructed optical properties using segmented, non-segmented, and adaptively segmented 3D mouse anatomy (MOBY) are used to perform bioluminescence tomography (BLT) for two simulated internal sources. The BLT results suggest that the accuracy of reconstruction of total source power obtained without the segmentation provided by an auxiliary imaging method such as x-ray CT is comparable to that obtained when using perfect segmentation. PMID:24694875

  1. Algorithm for localized adaptive diffuse optical tomography and its application in bioluminescence tomography

    Science.gov (United States)

    Naser, Mohamed A.; Patterson, Michael S.; Wong, John W.

    2014-04-01

    A reconstruction algorithm for diffuse optical tomography based on diffusion theory and finite element method is described. The algorithm reconstructs the optical properties in a permissible domain or region-of-interest to reduce the number of unknowns. The algorithm can be used to reconstruct optical properties for a segmented object (where a CT-scan or MRI is available) or a non-segmented object. For the latter, an adaptive segmentation algorithm merges contiguous regions with similar optical properties thereby reducing the number of unknowns. In calculating the Jacobian matrix the algorithm uses an efficient direct method so the required time is comparable to that needed for a single forward calculation. The reconstructed optical properties using segmented, non-segmented, and adaptively segmented 3D mouse anatomy (MOBY) are used to perform bioluminescence tomography (BLT) for two simulated internal sources. The BLT results suggest that the accuracy of reconstruction of total source power obtained without the segmentation provided by an auxiliary imaging method such as x-ray CT is comparable to that obtained when using perfect segmentation.

  2. "Quantum-optical coherence tomography" with classical light

    CERN Document Server

    Lavoie, Jonathan; Resch, Kevin J; 10.1364/OE.17.003818

    2009-01-01

    Quantum-optical coherence tomography (Q-OCT) is an interferometric technique for axial imaging offering several advantages over conventional methods. Chirped-pulse interferometry (CPI) was recently demonstrated to exhibit all of the benefits of the quantum interferometer upon which Q-OCT is based. Here we use CPI to measure axial interferograms to profile a sample accruing the important benefits of Q-OCT, including automatic dispersion cancellation, but with 10 million times higher signal. Our technique solves the artifact problem in Q-OCT and highlights the power of classical correlation in optical imaging.

  3. Optical spectroscopy and Doppler tomography of Cygnus X-2

    OpenAIRE

    Elebert, P.; Callanan, P. J.; Torres, M. A. P.; Garcia, M. R.

    2009-01-01

    We present phase resolved optical spectroscopy and Doppler tomography of V1341 Cygni, the optical counterpart to the neutron star low mass X-ray binary Cygnus X-2. We derive a radial velocity curve for the secondary star, finding a projected radial velocity semi-amplitude of K2 = 79 +/- 3 km/s, leading to a mass function of 0.51 +/- 0.06 Msun, ~30% lower than the previous estimate. We tentatively attribute the lower value of K2 (compared to that obtained by other authors) to...

  4. Local inversions in ultrasound-modulated optical tomography

    Science.gov (United States)

    Bal, Guillaume; Moskow, Shari

    2014-02-01

    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.

  5. Quantitative fluorescence diffuse optical tomography in the presence of heterogeneities.

    Science.gov (United States)

    Correia, Teresa; Ducros, Nicolas; D'Andrea, Cosimo; Schweiger, Martin; Arridge, Simon

    2013-06-01

    In fluorescence diffuse optical tomography (fDOT), the accuracy of reconstructed fluorescence distributions highly depends on the knowledge of the tissue optical heterogeneities for correct modeling of light propagation. Common approaches are to assume homogeneous optical properties or, when structural information is available, assign optical properties to various segmented organs, which is likely to result in inaccurate reconstructions. Furthermore, DOT based only on intensity (continuous wave-DOT) is a nonunique inverse problem, and hence, cannot be used to retrieve simultaneously maps of absorption and diffusion coefficients. We propose a method that reconstructs a single parameter from the excitation measurements, which is used in the fDOT problem to accurately recover fluorescence distribution. PMID:23722784

  6. Use of optical coherence tomography to evaluate papilledema and pseudopapilledema.

    Science.gov (United States)

    Heidary, Gena; Rizzo, Joseph F

    2010-01-01

    Idiopathic intracranial hypertension (IIH), or pseudotumor cerebri, describes a condition of elevated intracranial pressure (ICP) that typically presents in obese women of childbearing age with symptoms and signs of posture-dependent headaches, pulsatile tinnitus, visual changes, and papilledema. Optical coherence tomography (OCT) has begun to be utilized as an adjunctive, quantitative tool in the evaluation of patients with IIH to help distinguish between true optic nerve head edema and pseudopapilledema, and to contribute to our understanding of the consequences of prolonged optic nerve edema. Although few longitudinal studies of patients with IIH have been published to date, it appears that there may be a correlation between retinal nerve fiber layer (RNFL) thickness and visual function. With the new spectral domain OCT, additional parameters of the optic nerve imaging, including volume and height measurements, might provide greater sensitivity of the response to treatment and the long-term visual outcome in patients with IIH. PMID:21091000

  7. Mice lung disease follow-up with open-air fluorescence diffuse optical tomography

    Science.gov (United States)

    Koenig, Anne; Gonon, Georges; Hervé, Lionel; Berger, Michel; Dinten, Jean-Marc; Boutet, Jérôme; Josserand, Véronique; Coll, Jean-Luc; Peltié, Philippe; Rizo, Philippe

    2009-07-01

    A fluorescence diffuse optical tomography instrument including a dedicated reconstruction scheme which accounts for the medium optical heterogeneities is presented. It allows non-contact measurements and does not require animal immersion in an optical adaptation liquid.

  8. Cellular resolution volumetric in vivo retinal imaging with adaptive optics–optical coherence tomography?

    OpenAIRE

    Zawadzki, Robert J.; Choi, Stacey S.; Fuller, Alfred R.; Evans, Julia W.; Hamann, Bernd; Werner, John S.

    2009-01-01

    Ultrahigh-resolution adaptive optics–optical coherence tomography (UHR-AO-OCT) instrumentation allowing monochromatic and chromatic aberration correction was used for volumetric in vivo retinal imaging of various retinal structures including the macula and optic nerve head (ONH). Novel visualization methods that simplify AO-OCT data viewing are presented, and include co-registration of AO-OCT volumes with fundus photography and stitching of multiple AO-OCT sub-volumes to create a large fiel...

  9. Wavefront sensorless adaptive optics optical coherence tomography for in vivo retinal imaging in mice

    OpenAIRE

    Jian, Yifan; Xu, Jing; Gradowski, Martin A.; Bonora, Stefano; Zawadzki, Robert J.; Sarunic, Marinko V.

    2014-01-01

    We present wavefront sensorless adaptive optics (WSAO) Fourier domain optical coherence tomography (FD-OCT) for in vivo small animal retinal imaging. WSAO is attractive especially for mouse retinal imaging because it simplifies optical design and eliminates the need for wavefront sensing, which is difficult in the small animal eye. GPU accelerated processing of the OCT data permitted real-time extraction of image quality metrics (intensity) for arbitrarily selected retinal layers to be optimi...

  10. A Review on the use of Optical Coherence Tomography in Medical Imaging

    Directory of Open Access Journals (Sweden)

    A. Stella

    2011-02-01

    Full Text Available Optical Coherence Tomography (OCT is a Three-dimensional imaging technique with ultrahigh spatial resolution even in highly scattering media. It is based on measurements of the reflected light from tissue discontinuities. Optical coherence tomography delivers high resolution images, because the test is based on light, rather than sound or radio frequency. Optical coherence tomography provides a 1 to 15 µm resolution but only a depth of 1 to 2 mm can be imaged in opaque tissues such as arteries or skin. In transparent tissues such as the eye, greater imaging depths are possible. In addition, optical coherence tomography is capable of providing information about tissue composition. This paper, aims at reviewing the working principle of Optical Coherence Tomography and the quality of the image produced through this technique. A major drawback of Optical Coherence Tomography image is that, it suffers from speckle noise.

  11. Multispectral guided fluorescence diffuse optical tomography using upconverting nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Svenmarker, Pontus, E-mail: pontus.svenmarker@physics.umu.se [Department of Physics, Lund University, P.O. Box 118, SE-221 00 Lund (Sweden); Department of Physics, Umeå University, SE-901 87 Umeå (Sweden); Centre for Microbial Research (UCMR), Umeå University, SE-901 87 Umeå (Sweden); Xu, Can T.; Liu, Haichun; Wu, Xia; Andersson-Engels, Stefan [Department of Physics, Lund University, P.O. Box 118, SE-221 00 Lund (Sweden)

    2014-02-17

    We report on improved image detectability for fluorescence diffuse optical tomography using upconverting nanoparticles doped with rare-earth elements. Core-shell NaYF{sub 4}:Yb{sup 3+}/Er{sup 3+}@NaYF{sub 4} upconverting nanoparticles were synthesized through a stoichiometric method. The Yb{sup 3+}/Er{sup 3+} sensitizer-activator pair yielded two anti-Stokes shifted fluorescence emission bands at 540?nm and 660?nm, here used to a priori estimate the fluorescence source depth with sub-millimeter precision. A spatially varying regularization incorporated the a priori fluorescence source depth estimation into the tomography reconstruction scheme. Tissue phantom experiments showed both an improved resolution and contrast in the reconstructed images as compared to not using any a priori information.

  12. Multispectral guided fluorescence diffuse optical tomography using upconverting nanoparticles

    International Nuclear Information System (INIS)

    We report on improved image detectability for fluorescence diffuse optical tomography using upconverting nanoparticles doped with rare-earth elements. Core-shell NaYF4:Yb3+/Er3+@NaYF4 upconverting nanoparticles were synthesized through a stoichiometric method. The Yb3+/Er3+ sensitizer-activator pair yielded two anti-Stokes shifted fluorescence emission bands at 540?nm and 660?nm, here used to a priori estimate the fluorescence source depth with sub-millimeter precision. A spatially varying regularization incorporated the a priori fluorescence source depth estimation into the tomography reconstruction scheme. Tissue phantom experiments showed both an improved resolution and contrast in the reconstructed images as compared to not using any a priori information

  13. Optical Coherence Tomography and Autofluorescence Imaging of Human Tonsil

    Science.gov (United States)

    Pahlevaninezhad, Hamid; Lee, Anthony M. D.; Rosin, Miriam; Sun, Ivan; Zhang, Lewei; Hakimi, Mehrnoush; MacAulay, Calum; Lane, Pierre M.

    2014-01-01

    For the first time, we present co-registered autofluorescence imaging and optical coherence tomography (AF/OCT) of excised human palatine tonsils to evaluate the capabilities of OCT to visualize tonsil tissue components. Despite limited penetration depth, OCT can provide detailed structural information about tonsil tissue with much higher resolution than that of computed tomography, magnetic resonance imaging, and Ultrasound. Different tonsil tissue components such as epithelium, dense connective tissue, lymphoid nodules, and crypts can be visualized by OCT. The co-registered AF imaging can provide matching biochemical information. AF/OCT scans may provide a non-invasive tool for detecting tonsillar cancers and for studying the natural history of their development. PMID:25542010

  14. Multispectral guided fluorescence diffuse optical tomography using upconverting nanoparticles

    Science.gov (United States)

    Svenmarker, Pontus; Xu, Can T.; Liu, Haichun; Wu, Xia; Andersson-Engels, Stefan

    2014-02-01

    We report on improved image detectability for fluorescence diffuse optical tomography using upconverting nanoparticles doped with rare-earth elements. Core-shell NaYF4:Yb3+/Er3+@NaYF4 upconverting nanoparticles were synthesized through a stoichiometric method. The Yb3+/Er3+ sensitizer-activator pair yielded two anti-Stokes shifted fluorescence emission bands at 540 nm and 660 nm, here used to a priori estimate the fluorescence source depth with sub-millimeter precision. A spatially varying regularization incorporated the a priori fluorescence source depth estimation into the tomography reconstruction scheme. Tissue phantom experiments showed both an improved resolution and contrast in the reconstructed images as compared to not using any a priori information.

  15. Co-registration of glucose metabolism with positron emission tomography and vascularity with fluorescent diffuse optical tomography in mouse tumors.

    OpenAIRE

    Tong, Xiao; Garofalakis, Anikitos; Dubois, Albertine; Boisgard, Raphae?l; Duconge?, Fre?de?ric; Tre?bossen, Re?gine; Tavitian, Bertrand

    2012-01-01

    ABSTRACT: BACKGROUND: Bimodal molecular imaging with fluorescence diffuse optical tomography (fDOT) and positron emission tomography (PET) has the capacity to provide multiple molecular information of mouse tumors. The objective of the present study is to co-register fDOT and PET molecular images of tumors in mice automatically. METHODS: The coordinates of bimodal fiducial markers (FM) in regions of detection were automatically detected in planar optical images (x, y positions) in laser patte...

  16. 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.

  17. In vivo endoscopic multi-beam optical coherence tomography

    International Nuclear Information System (INIS)

    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 ?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.

  18. Piezoelectric scanning mirrors for endoscopic optical coherence tomography

    International Nuclear Information System (INIS)

    A novel piezoelectric scanning mirror design for endoscopic optical coherence tomography (OCT) is presented. OCT is an interferometric technique providing microscopic tomographic sectioning of biological samples with mm-range penetration capability in tissue and is suited for integration with endoscopes using fiber-based light delivery to the sample. The piezoelectric scanning mirror was designed to provide wide-range rapid forwarding-looking scanning of the optical beam at the distal end of a compact catheter. The optical scanner provides a large ratio of mirror aperture to device size with rectangular mirror sizes ranging from 600 µm × 840 µm to 840 µm × 1600 µm. Static angular displacements up to ±7° (mechanical angle) were demonstrated and resonance frequencies of hundreds of Hz (and up to 1–2 kHz) were measured, depending on the mirror size. The imaging capability of the piezoelectric scanner was demonstrated using a bench-top spectrometer-based Fourier-domain OCT system

  19. Self-calibrated algorithms for diffuse optical tomography and bioluminescence tomography using relative transmission images.

    Science.gov (United States)

    Naser, Mohamed A; Patterson, Michael S; Wong, John W

    2012-11-01

    Reconstruction algorithms for diffuse optical tomography (DOT) and bioluminescence tomography (BLT) have been developed based on diffusion theory. The algorithms numerically solve the diffusion equation using the finite element method. The direct measurements of the uncalibrated light fluence rates by a camera are used for the reconstructions. The DOT is self-calibrated by using all possible pairs of transmission images obtained with external sources along with the relative values of the simulated data and the calculated Jacobian. The reconstruction is done in the relative domain with the cancelation of any geometrical or optical factors. The transmission measurements for the DOT are used for calibrating the bioluminescence measurements at each wavelength and then a normalized system of equations is built up which is self-calibrated for the BLT. The algorithms have been applied to a three dimensional model of the mouse (MOBY) segmented into tissue regions which are assumed to have uniform optical properties. The DOT uses the direct method for calculating the Jacobian. The BLT uses a reduced space of eigenvectors of the Green's function with iterative shrinking of the permissible source region. The reconstruction results of the DOT and BLT algorithms show good agreement with the actual values when using either absolute or relative data. Even a small calibration error causes significant degradation of the reconstructions based on absolute data. PMID:23162719

  20. Detecting cell death with optical coherence tomography and envelope statistics

    Science.gov (United States)

    Farhat, Golnaz; Yang, Victor X. D.; Czarnota, Gregory J.; Kolios, Michael C.

    2011-02-01

    Currently no standard clinical or preclinical noninvasive method exists to monitor cell death based on morphological changes at the cellular level. In our past work we have demonstrated that quantitative high frequency ultrasound imaging can detect cell death in vitro and in vivo. In this study we apply quantitative methods previously used with high frequency ultrasound to optical coherence tomography (OCT) to detect cell death. The ultimate goal of this work is to use these methods for optically-based clinical and preclinical cancer treatment monitoring. Optical coherence tomography data were acquired from acute myeloid leukemia cells undergoing three modes of cell death. Significant increases in integrated backscatter were observed for cells undergoing apoptosis and mitotic arrest, while necrotic cells induced a decrease. These changes appear to be linked to structural changes observed in histology obtained from the cell samples. Signal envelope statistics were analyzed from fittings of the generalized gamma distribution to histograms of envelope intensities. The parameters from this distribution demonstrated sensitivities to morphological changes in the cell samples. These results indicate that OCT integrated backscatter and first order envelope statistics can be used to detect and potentially differentiate between modes of cell death in vitro.

  1. Compressive sensing optical coherence tomography using randomly accessible lasers

    Science.gov (United States)

    Harfouche, Mark; Satyan, Naresh; Vasilyev, Arseny; Yariv, Amnon

    2014-05-01

    We propose and demonstrate a novel a compressive sensing swept source optical coherence tomography (SSOCT) system that enables high speed images to be taken while maintaining the high resolution offered from a large bandwidth sweep. Conventional SSOCT systems sweep the optical frequency of a laser ?(t) to determine the depth of the reflectors at a given lateral location. A scatterer located at delay ? appears as a sinusoid cos (?(t)? ) at the photodetector. The finite optical chirp rate and the speed of analog to digital and digital to analog converters limit the acquisition rate of an axial scan. The proposed acquisition modality enables much faster image acquisition rates by interrogating the beat signal at randomly selected optical frequencies while preserving resolution and depth of field. The system utilizes a randomly accessible laser, a modulated grating Y-branch laser, to sample the interference pattern from a scene at randomly selected optical frequencies over an optical bandwidth of 5 THz , corresponding to a resolution of 30 ?m in air. The depth profile is then reconstructed using an l1 minimization algorithm with a LASSO constraint. Signal-dependent noise sources, shot noise and phase noise, are analyzed and taken into consideration during the recovery. Redundant dictionaries are used to improve the reconstruction of the depth profile. A compression by a factor of 10 for sparse targets up to a depth of 15 mm in noisy environments is shown.

  2. [Imaging of actinic porokeratosis by optical coherence tomography (OCT)].

    Science.gov (United States)

    von Felbert, V; Neis, M; Megahed, M; Spöler, F

    2008-11-01

    Disseminated superficial actinic porokeratosis (DSAP) is a rare, genetically heterogeneous skin disorder. We report a case of a 73-year-old female patient who was diagnosed with DSAP by optical coherence tomography (OCT) and histology. During the last 4 years prior to diagnosis, she had developed numerous (pre)malignant lesions of the skin of the lower legs including actinic keratoses, squamous cell carcinomas and Bowen's disease. DSAP lesions and actinic keratoses were resistant to topical treatment with imiquimod and retinoids, but improved with photodynamic therapy (PDT). PMID:18931984

  3. Polarization Effects in Optical Coherence Tomography of Various Biological Tissues

    Science.gov (United States)

    de Boer, Johannes F.; Srinivas, Shyam M.; Park, B. Hyle; Pham, Tuan H.; Chen, Zhongping; Milner, Thomas E.; Nelson, J. Stuart

    2015-01-01

    Polarization sensitive optical coherence tomography (PS-OCT) was used to obtain spatially resolved ex vivo images of polarization changes in skeletal muscle, bone, skin and brain. Through coherent detection of two orthogonal polarization states of the signal formed by interference of light reflected from the biological sample and a mirror in the reference arm of a Michelson interferometer, the depth resolved change in polarization was measured. Inasmuch as any fibrous structure will influence the polarization of light, PS-OCT is a potentially powerful technique investigating tissue structural properties. In addition, the effects of single polarization state detection on OCT image formation is demonstrated.

  4. Capturing the vital vascular fingerprint with optical coherence tomography.

    Science.gov (United States)

    Liu, Gangjun; Chen, Zhongping

    2013-08-01

    Using fingerprints as a method to identify an individual has been accepted in forensics since the nineteenth century, and the fingerprint has become one of the most widely used biometric characteristics. Most of the modern fingerprint recognition systems are based on the print pattern of the finger surface and are not robust against spoof attaching. We demonstrate a novel vital vascular fingerprint system using Doppler optical coherence tomography that provides highly sensitive and reliable personal identification. Because the system is based on blood flow, which only exists in a livng person, the technique is robust against spoof attaching. PMID:23913068

  5. Spectral domain optical coherence tomography characteristics in diabetic retinopathy

    Science.gov (United States)

    Gella, Laxmi; Raman, Rajiv; Rani, Padmaja Kumari; Sharma, Tarun

    2014-01-01

    Purpose: To report the appearance of diabetic retinopathy lesions using spectral domain optical coherence tomography (SD-OCT). Materials and Methods: A total of 287 eyes of 199 subjects were included. All the subjects underwent complete ophthalmic examination including SD-OCT. Results: The appearance of various lesions of diabetic retinopathy and the retinal layers involved were reported. In subjects with macular edema the prevalence of incomplete PVD was 55.6%. Conclusion: SD-OCT brings new insights into the morphological changes of the retina in diabetic retinopathy. PMID:25378876

  6. Ultrahigh speed endoscopic optical coherence tomography for gastroenterology

    OpenAIRE

    Tsai, Tsung-han; Lee, Hsiang-chieh; Ahsen, Osman O.; Liang, Kaicheng; Giacomelli, Michael G.; Potsaid, Benjamin M.; Tao, Yuankai K.; Jayaraman, Vijaysekhar; Figueiredo, Marisa; Huang, Qin; Cable, Alex E.; Fujimoto, James; Mashimo, Hiroshi

    2014-01-01

    We describe an ultrahigh speed endoscopic swept source optical coherence tomography (OCT) system for clinical gastroenterology using a vertical-cavity surface-emitting laser (VCSEL) and micromotor imaging catheter. The system had a 600 kHz axial scan rate and 8 µm axial resolution in tissue. Imaging was performed with a 3.2 mm diameter imaging catheter at 400 frames per second with a 12 µm spot size. Three-dimensional OCT (3D-OCT) imaging was performed in patients with a cross section of pa...

  7. Speckle reduction in optical coherence tomography images using tissue viscoelasticity

    OpenAIRE

    Kennedy, Brendan F.; Curatolo, Andrea; Sampson, David D.; Hillman, Timothy Robert; Saunders, Christobel M.

    2011-01-01

    We present a technique to reduce speckle in optical coherence tomography images of soft tissues. An average is formed over a set of B-scans that have been decorrelated by viscoelastic creep strain. The necessary correction for the deformation-induced spatial distortions between B-scans is achieved through geometrical co-registration using an affine transformation. Speckle reduction by up to a factor of 1.65 is shown in images of tissue-mimicking soft fibrin phantoms and excised human lymph no...

  8. Megahertz streak-mode Fourier domain optical coherence tomography

    OpenAIRE

    Wang, Rui; Yun, Julie X.; Yuan, Xiaocong; Goodwin, Richard; Markwald, Roger R.; Gao, Bruce Z.

    2011-01-01

    Here we present an ultrahigh-speed Fourier-domain optical coherence tomography (OCT) that records the OCT spectrum in streak mode with a high-speed area scan camera, which allows higher OCT imaging speed than can be achieved with a line-scan camera. Unlike parallel OCT techniques that also use area scan cameras, the conventional single-mode fiber-based point-scanning mechanism is retained to provide a confocal gate that rejects multiply scattered photons from the sample. When using a 1000 Hz ...

  9. Optical coherence tomography in art diagnostics and restoration

    Science.gov (United States)

    Targowski, P.; Rouba, B.; Góra, M.; Tymi?ska-Widmer, L.; Marczak, J.; Kowalczyk, A.

    2008-07-01

    An overview of the technique of optical coherence tomography (OCT) is presented, and a spectral OCT instrument especially designed for art diagnostics is described. The applicability of OCT to the stratigraphy of oil paintings is discussed with emphasis on examination of the artist’s signature. For the first time, OCT tomograms of stained glass are presented and discussed. The utilisation of Spectral OCT in real-time monitoring of varnish ablation is discussed with examples of ablation, melting and evaporation, and exfoliation of the varnish layer provided, for the first time.

  10. Combined two-photon microscopy and angiographic optical coherence tomography

    Science.gov (United States)

    Kim, Bumju; Wang, Tae Jun; Li, Qingyun; Nam, Jutaek; Hwang, Sekyu; Chung, Euiheon; Kim, Sungjee; Kim, Ki Hean

    2013-08-01

    A combined two-photon microscopy (TPM) and angiographic optical coherence tomography (OCT) is developed, which can provide molecular, cellular, structural, and vascular information of tissue specimens in vivo. This combined system is implemented by adding an OCT vasculature visualization method to the previous combined TPM and OCT, and then is applied to in vivo tissue imaging. Two animal models, a mouse brain cranial window model and a mouse ear cancer model, are used. Both molecular, cellular information at local regions of tissues, and structural, vascular information at relatively larger regions are visualized in the same sections. In vivo tissue microenvironments are better elucidated by the combined TPM and angiographic OCT.

  11. Multiple projection optical diffusion tomography with plane wave illumination

    International Nuclear Information System (INIS)

    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

  12. Multiple Projection Optical Diffusion Tomography with Plane Wave Illumination

    CERN Document Server

    Markel, V A; 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 can be much more easily fitted into 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.

  13. Reflectance diffuse optical tomography. Its application to human brain mapping

    International Nuclear Information System (INIS)

    We report the successful application of reflectance diffuse optical tomography (DOT) using near-infrared light with the new reconstruction algorithm that we developed to the observation of regional hemodynamic changes in the brain under specific mental tasks. Our results reveal the heterogeneous distribution of oxyhemoglobin and deoxyhemoglobin in the brain, showing complementary images of oxyhemoglobin and deoxyhemoglobin changes in certain regions. We conclude that our reflectance DOT has practical potential for human brain mapping, as well as in the diagnostic imaging of brain diseases. (author)

  14. Handheld Optical Coherence Tomography Scanner for Primary Care Diagnostics

    OpenAIRE

    Jung, Woonggyu; Kim, Jeehyun; Jeon, Mansik; Chaney, Eric J.; Stewart, Charles N.; Boppart, Stephen A.

    2010-01-01

    The goal of this study is to develop an advanced point-of-care diagnostic instrument for use in a primary care office using handheld optical coherence tomography (OCT). This system has the potential to enable earlier detection of diseases and accurate image-based diagnostics. Our system was designed to be compact, portable, user-friendly, and fast, making it well suited for the primary care office setting. The unique feature of our system is a versatile handheld OCT imaging scanner which cons...

  15. Noncontact fluorescence diffuse optical tomography of heterogeneous media

    Science.gov (United States)

    Hervé, L.; Koenig, A.; da Silva, A.; Berger, M.; Boutet, J.; Dinten, J. M.; Peltié, P.; Rizo, P.

    2007-08-01

    Fluorescence-enhanced diffuse optical tomography is expected to be useful to the collection of functional information from small animal models. This technique is currently limited by the extent of tissue heterogeneity and management of the shape of the animals. We propose an approach based on the reconstruction of object heterogeneity, which provides an original solution to the two problems. Three evaluation campaigns are described: the first two were performed on phantoms designed to test the reconstructions in highly heterogeneous media and noncontact geometries; the third was conducted on mice with lung tumors to test fluorescence yield reconstruction feasibility in vivo.

  16. Quantification of retinal lesions by polarization sensitive optical coherence tomography

    Science.gov (United States)

    Hitzenberger, Christoph K.; Baumann, Bernhard; Götzinger, Erich; Pircher, Michael; Sattmann, Harald; Ahlers, Christian; Schütze, Christopher; Schlanitz, Ferdinand; Schmidt-Erfurth, Ursula

    2010-02-01

    Segmentation of retinal structures is an important step for quantitative diagnostic applications of optical coherence tomography (OCT) in ophthalmology. Contrary to previous segmentation algorithms that are based on intensity images, we use the tissue specific contrast provided by polarization sensitive (PS) OCT for segmentation of retinal layers and lesions. Our algorithms exploit the polarization scrambling property of the retinal pigment epithelium (RPE) in a first step to segment the RPE. The RPE is then used as a "backbone" to identify further structures like the normal RPE position (indicating Bruch's membrane) or the posterior tips of the photoreceptors. In a final step, lesions like drusen, RPE atrophies, and subretinal fluids are segmented.

  17. Efficient sweep buffering in swept source optical coherence tomography using a fast optical switch

    OpenAIRE

    Dhalla, Al-hafeez; Shia, Kevin; Izatt, Joseph A.

    2012-01-01

    We describe a novel buffering technique for increasing the A-scan rate of swept source optical coherence tomography (SSOCT) systems employing low duty cycle swept source lasers. This technique differs from previously reported buffering techniques in that it employs a fast optical switch, capable of switching in 60 ns, instead of a fused fiber coupler at the end of the buffering stage, and is therefore appreciably more power efficient. The use of the switch also eliminates patient exposure to ...

  18. Wavefront sensorless modal deformable mirror correction in adaptive optics: optical coherence tomography.

    Science.gov (United States)

    Bonora, S; Zawadzki, R J

    2013-11-15

    We present a method for optimization of optical coherence tomography images using wavefront sensorless adaptive optics. The method consists of systematic adjustment of the coefficients of a subset of the orthogonal Zernike bases and application of the resulting shapes to a deformable mirror, while optimizing using image sharpness as a merit function. We demonstrate that this technique can compensate for aberrations induced by trial lenses. Measurements of the point spread function before and after compensation demonstrate near diffraction limit imaging. PMID:24322136

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

    OpenAIRE

    Jh, Tzu; Hw, Flynn Jr; Am, Berrocal; We, Smiddy; Tg, Murray; Yl, Fisher

    2013-01-01

    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 investiga...

  20. Clinical analysis of buried optic nerve drusen with optical coherence tomography examination

    Directory of Open Access Journals (Sweden)

    Juan Liu

    2013-11-01

    Full Text Available AIM: To explore the specific image of buried optic nerve drusen during optical coherence tomography(OCTexamination. METHODS: A retrospective study was made on 6 patients with buried optic nerve drusen(6 eyesdiagnosed by fundus fluorescein angiography(FFAand B scan examination. RESULTS: The high fluorescence area of optic disc showed on the FFA image of all 6 patients imaged with the spectral OCT revealed cluster of calcium deposits. These deposits demonstrated specific wide bars with high reflectivity casting shadows underneath and had lacunae appearance. CONCLUSION: Buried optic nerve drusen showed specific image in the spectral OCT examination. Thus, spectral OCT can serve as an assistant examination method with relatively prominent features for diagnosing buried optic nerve drusen. It can help to raise the detection rate of buried optic nerve drusen.

  1. Indocyanine green enhanced co-registered diffuse optical tomography and photoacoustic tomography

    Science.gov (United States)

    Xu, Chen; Kumavor, Patrick D.; Alqasemi, Umar; Li, Hai; Xu, Yan; Zanganeh, Saeid; Zhu, Quing

    2013-12-01

    To overcome the intensive light scattering in biological tissue, diffuse optical tomography (DOT) in the near-infrared range for breast lesion detection is usually combined with other imaging modalities, such as ultrasound, x-ray, and magnetic resonance imaging, to provide guidance. However, these guiding imaging modalities may depend on different contrast mechanisms compared to the optical contrast in the DOT. As a result, they cannot provide reliable guidance for DOT because some lesions may not be detectable by a nonoptical modality but may have a high optical contrast. An imaging modality that relies on optical contrast to provide guidance is desirable for DOT. We present a system that combines a frequency-domain DOT and real-time photoacoustic tomography (PAT) systems to detect and characterize deeply seated targets embedded in a turbid medium. To further improve the contrast, the exogenous contrast agent, indocyanine green (ICG), is used. Our experimental results show that the combined system can detect a tumor-mimicking phantom, which is immersed in intralipid solution with the concentrations ranging from 100 to 10 ?M and with the dimensions of 0.8 cm×0.8 cm×0.6 cm, up to 2.5 cm in depth. Mice experiments also confirmed that the combined system can detect tumors and monitor the ICG uptake and washout in the tumor region. This method can potentially improve the accuracy to detect small breast lesions as well as lesions that are sensitive to background tissue changes, such as the lesions located just above the chest wall.

  2. Optical coherence tomography image enhancement by using gold nanoparticles

    Science.gov (United States)

    Ponce-de-Leon, Y. R.; Lopez-Rios, J. A.; Pichardo-Molina, J. L.; Alcalá Ochoa, N.

    2011-08-01

    Optical Coherence Tomography (OCT) is an imaging technique to get cross-sectional images with resolutions of a few microns and deep penetration in tissue of some millimeters. For many years OCT has been applied to analyze different human tissues like eyes, skin, teeth, urinary bladders, gastrointestinal, respiratory or genitourinary tracts and recently breast cancer tissues have been studied. Many of these tissues are composed specially of lipids and collagen, proteins which cause multiple light scattering (MLS) reducing significantly the optical depth and the contrast of OCT imaging. So, one of the big challenges of this technique is to acquire images with good contrast. Gold nanoparticles (NPs) exhibit interesting optical properties due to its plasmon resonance frequency. Optical absorbance is strong when gold NPs have dimension under 50 nm, but over this size optical scattering becomes dominant. In this work we show the preliminary results of the use of gold NPs as a contrast medium to enhance the OCT images quality. Our experimental results show which type of particles (morphology and size) present the best enhancement in the region of 1325 nm which corresponds to the central wavelength source excitation. All our experiments were carried out with a commercial OCT (thorlabs) system and our NPs were tested in water and gel phantoms.

  3. Diffuse optical tomography with a priori anatomical information

    International Nuclear Information System (INIS)

    Diffuse optical tomography (DOT) poses a typical ill-posed inverse problem with a limited number of measurements and inherently low spatial resolution. In this paper, we propose a hierarchical Bayesian approach to improve spatial resolution and quantitative accuracy by using a priori information provided by a secondary high resolution anatomical imaging modality, such as magnetic resonance (MR) or x-ray. In such a dual imaging approach, while the correlation between optical and anatomical images may be high, it is not perfect. For example, a tumour may be present in the optical image, but may not be discernable in the anatomical image. The proposed hierarchical Bayesian approach allows incorporation of partial a priori knowledge about the noise and unknown optical image models, thereby capturing the function-anatomy correlation effectively. We present a computationally efficient iterative algorithm to simultaneously estimate the optical image and the unknown a priori model parameters. Extensive numerical simulations demonstrate that the proposed method avoids undesirable bias towards anatomical prior information and leads to significantly improved spatial resolution and quantitative accuracy

  4. Second order inverse born approximation for diffuse optical tomography

    Science.gov (United States)

    Kwon, Kiwoon; Kim, Beop-Min

    2008-02-01

    Diffuse Optical Tomography (DOT) involves a nonlinear optimization problem to find the tissue optical properties by measuring near-infrared light noninvasively. Many researchers used linearization methods to obtain the optical image in real time. However, the linearization procedure may neglect small but sometimes important regions such as small tumors at an early stage. Therefore, nonlinear optimization methods such as gradient- or Newton- type methods are exploited, resulting in better resolution image than that of linearization methods. But the disadvantage of nonlinear methods is that they need much computation time. To solve this trade-off dilemma between image resolution and computing time, we suggest second order inverse Born expansion algorithm in this paper. It is known that a small perturbation of photon density is represented by Born expansion with respect to the perturbation of optical coefficients, which is an infinite series of integral operators having Robin function kernel. Whereas, inverse Born expansion is an implicit representation of a small perturbation of optical coefficients by an infinite series of the integral operators with respect to the photon density and its perturbation, which is appropriate series expansion for inverse DOT problem. Solving the inverse Born expansion itself and the first order approximation correspond to nonlinear and linear method, respectively. We formulated a second order approximation of the inverse Born expansion explicitly to make numerical implementation possible and showed the convergence order of the proposed method is higher than the linear method.

  5. Imaging of oral pathological tissue using optical coherence tomography

    Science.gov (United States)

    Canjau, Silvana; Todea, Carmen; Sinescu, Cosmin; Duma, Virgil-Florin; Topala, Florin I.; Podoleanu, Adrian G.

    2014-01-01

    Oral squamous cell carcinoma (OSCC) constitutes 90% of oral cancer. Early detection is a cornerstone to improve survival. Interaction of light with tissues may highlight changes in tissue structure and metabolism. We propose optical coherence tomography (OCT), as a non-invasive diagnosis method, being a new high-resolution optical technique that permits tri-dimensional (3-D), real-time imaging of near surface abnormalities in complex tissues. In this study half of the excisional biopsy was directed to the pathologist and the other half was assigned for OCT investigation. Histopathology validated the results. Areas of OSCC of the buccal mucosa were identified in the OCT images. The elements obserced included extensive epithelial down-growth, the disruption of the basement membrane, with areas of erosion, an epithelial layer that was highly variable in thickness and invasion into the sub-epithelial layers. Therefore, OCT appears to be a highly promising imaging modality.

  6. Continuous focus tracking for real-time optical coherence tomography

    Science.gov (United States)

    Cobb, Michael J.; Liu, Xiumei; Li, Xingde

    2005-07-01

    We report an approach to achieving continuous focus tracking and a depth-independent transverse resolution for real-time optical coherence tomography (OCT) imaging. Continuous real-time focus tracking is permitted by use of a lateral-priority image acquisition sequence in which the depth-scanning rate is equivalent to the imaging frame rate. Real-time OCT imaging with continuous focus tracking is performed at 1 frame/s by reciprocal translation of a rapid lateral-scanning miniature imaging probe (e.g., an endoscope). The optical path length in the reference arm is scanned synchronously to ensure that the coherence gate coincides with the imaging beam focus. The image quality improvement is experimentally demonstrated by imaging a tissue phantom embedded with polystyrene microspheres and rabbit esophageal tissues.

  7. Sound field reconstruction using acousto-optic tomography

    DEFF Research Database (Denmark)

    Torras Rosell, Antoni; Barrera Figueroa, Salvador

    2012-01-01

    When sound propagates through a medium, it results in pressure fluctuations that change the instantaneous density of the medium. Under such circumstances, the refractive index that characterizes the propagation of light is not constant, but influenced by the acoustic field. This kind of interaction is known as the acousto-optic effect. The formulation of this physical phenomenon into a mathematical problem can be described in terms of the Radon transform, which makes it possible to reconstruct an arbitrary sound field using tomography. The present work derives the fundamental equations governing the acousto-optic effect in air, and demonstrates that it can be measured with a laser Doppler vibrometer in the audible frequency range. The tomographic reconstruction is tested by means of computer simulations and measurements. The main features observed in the simulations are also recognized in the experimental results. The effectiveness of the tomographic reconstruction is further confirmed with representations ofthe very same sound field measured with a traditional microphone array.

  8. One specific velocity color mapping using optical coherence tomography.

    Science.gov (United States)

    Proskurin, Sergey G; Potlov, Anton Yu; Frolov, Sergej V

    2015-05-01

    Depth resolved coherence gating along with Doppler shift detection of the carrier frequency is used for one predetermined velocity mapping in different flows. Bidirectional rapid scanning optical delay of optical coherence tomography system is applied in the reference arm. Tilted capillary entry is used as a hydrodynamic phantom to model a sign-variable flow with complex geometry. Structural and one specific velocity images are obtained from the scanning interferometer signal processing in the frequency domain using analog and digital filtering. A standard structural image is decomposed into three parts: stationary object, and positive and negative velocity distributions. The latter two show equivelocity maps of the flow. The final image is represented as the complexation of the three. PMID:25679878

  9. Transversal phase resolved polarization sensitive optical coherence tomography

    International Nuclear Information System (INIS)

    We present a novel optical coherence tomography (OCT) method to measure backscattered intensity and birefringence properties (retardation and fast axis orientation) and apply it to imaging of human ocular tissue. The method is based on a Mach Zehnder interferometer, on transversal scanning, and on a polarization sensitive two-channel detection. A highly stable carrier frequency is generated by acousto-optic modulators (AOMs). This allows a phase sensitive demodulation by the lock-in technique. Since the recording of individual interference fringes is avoided by this method the amount of data to be recorded and processed is considerably reduced. We demonstrate this method on human cornea and anterior chamber angle and present, to the best of our knowledge, the first OCT images of retardation and fast axis orientation of the anterior chamber angle region in vivo

  10. Non-diffusing photochromic gel for optical computed tomography phantoms

    International Nuclear Information System (INIS)

    This study examines photochromic response in radiation sensitive hydrogels. Genipin, crosslinked, gelatin gel can support high resolution images because the chromophores do not diffuse. A low power, 633 nm He-Ne laser was used to write lines into the gels by a photobleaching reaction. Optical cone-beam computed tomography (CBCT) scans mapped the high resolution images in 3D with 0.25 mm voxel resolution. A straight line was written into a deformed gel and then readout in its relaxed, initial shape. The curved, photo-bleached line demonstrated deformable 3D dosimetry is possible with this system to the balloon edge. High resolution, photochromic images provide key information for characterizing optical CT scanners and 3D dosimeters. Many, ionizing radiation, dosimeter materials demonstrate either a photochromic or photothermal response, allowing this approach to be widely used in quantitative 3D scanning.

  11. Diffuse optical tomography: Present status and its future

    Science.gov (United States)

    Yamada, Yukio; Okawa, Shinpei

    2014-05-01

    Diffuse optical tomography (DOT) is one of the emerging modalities for the non-invasive imaging of thick biological tissues using near-infrared (NIR) light. This article reviews the fundamentals and development of DOT technology since its advent in the early 1990s, including the modeling of light propagation in biological tissues which strongly scatter and weakly absorb NIR light, the optical properties of biological tissues in the NIR wavelength range, three typical measurement methods, image reconstruction algorithms, and so forth. Then various studies are referred to for improvement of the DOT images, which are essentially low in quality due to the ill-conditioned and underdetermined problem. Studies and clinical applications presently attracting much attention are discussed in some detail. Finally, the expected future developments are summarized.

  12. Monte Carlo Simulations of Arterial Imaging with Optical Coherence Tomography

    Energy Technology Data Exchange (ETDEWEB)

    Amendt, P.; Estabrook, K.; Everett, M.; London, R.A.; Maitland, D.; Zimmerman, G.; Colston, B.; da Silva, L.; Sathyam, U.

    2000-02-01

    The laser-tissue interaction code LATIS [London et al., Appl. Optics 36, 9068 ( 1998)] is used to analyze photon scattering histories representative of optical coherence tomography (OCT) experiment performed at Lawrence Livermore National Laboratory. Monte Carlo photonics with Henyey-Greenstein anisotropic scattering is implemented and used to simulate signal discrimination of intravascular structure. An analytic model is developed and used to obtain a scaling law relation for optimization of the OCT signal and to validate Monte Carlo photonics. The appropriateness of the Henyey-Greenstein phase function is studied by direct comparison with more detailed Mie scattering theory using an ensemble of spherical dielectric scatterers. Modest differences are found between the two prescriptions for describing photon angular scattering in tissue. In particular, the Mie scattering phase functions provide less overall reflectance signal but more signal contrast compared to the Henyey-Greenstein formulation.

  13. Analysis of multiple scattering effects in optical Doppler tomography

    DEFF Research Database (Denmark)

    Yura, H.T.; Thrane, L.

    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 Doppler frequency spectrum. Thus, in the present analysis, the dependence of the mean and standard deviation of the Doppler shift on the scattering properties of the flowing medium are obtained. Taking the multiple scattering effects into account, we are able to explain previous measurements of depth-resolved retinal flow profiles where the influence of multiple scattering was observed [Yazdanfar et al., Opt. Lett. 25, 1448 (2000)]. To the best of our knowledge, no analytical model exists that are able to explain these observations.

  14. Weighted filtered backprojection for quantitative fluorescence optical projection tomography

    Science.gov (United States)

    Darrell, A.; Meyer, H.; Marias, K.; Brady, M.; Ripoll, J.

    2008-07-01

    Reconstructing images from a set of fluorescence optical projection tomography (OPT) projections is a relatively new problem. Several physical aspects of fluorescence OPT necessitate a different treatment of the inverse problem to that required for non-fluorescence tomography. Given a fluorophore within the depth of field of the imaging system, the power received by the optical system, and therefore the CCD detector, is related to the distance of the fluorophore from the objective entrance pupil. Additionally, due to the slight blurring of images of sources positioned off the focal plane, the CCD image of a fluorophore off the focal plane is lower in intensity than the CCD image of an identical fluorophore positioned on the focal plane. The filtered backprojection (FBP) algorithm does not take these effects into account and so cannot be expected to yield truly quantitative results. A full model of image formation is introduced which takes into account the effects of isotropic emission and defocus. The model is used to obtain a weighting function which is used in a variation of the FBP algorithm called weighted filtered backprojection (WFBP). This new algorithm is tested with simulated data and with experimental data from a phantom consisting of fluorescent microspheres embedded in an agarose gel.

  15. Molecular imaging true-colour spectroscopic optical coherence tomography

    Science.gov (United States)

    Robles, Francisco E.; Wilson, Christy; Grant, Gerald; Wax, Adam

    2011-12-01

    Molecular imaging holds a pivotal role in medicine due to its ability to provide invaluable insight into disease mechanisms at molecular and cellular levels. To this end, various techniques have been developed for molecular imaging, each with its own advantages and disadvantages. For example, fluorescence imaging achieves micrometre-scale resolution, but has low penetration depths and is mostly limited to exogenous agents. Here, we demonstrate molecular imaging of endogenous and exogenous chromophores using a novel form of spectroscopic optical coherence tomography. Our approach consists of using a wide spectral bandwidth laser source centred in the visible spectrum, thereby allowing facile assessment of haemoglobin oxygen levels, providing contrast from readily available absorbers, and enabling true-colour representation of samples. This approach provides high spectral fidelity while imaging at the micrometre scale in three dimensions. Molecular imaging true-colour spectroscopic optical coherence tomography (METRiCS OCT) has significant implications for many biomedical applications including ophthalmology, early cancer detection, and understanding fundamental disease mechanisms such as hypoxia and angiogenesis.

  16. Optical spectroscopy and Doppler tomography of Cygnus X-2

    CERN Document Server

    Elebert, P; Torres, M A P; García, M R

    2009-01-01

    We present phase resolved optical spectroscopy and Doppler tomography of V1341 Cygni, the optical counterpart to the neutron star low mass X-ray binary Cygnus X-2. We derive a radial velocity curve for the secondary star, finding a projected radial velocity semi-amplitude of K2 = 79 +/- 3 km/s, leading to a mass function of 0.51 +/- 0.06 Msun, ~30% lower than the previous estimate. We tentatively attribute the lower value of K2 (compared to that obtained by other authors) to variations in the X-ray irradiation of the secondary star at different epochs of observations. The limited phase coverage and/or longer timebase of previous observations may also contribute to the difference in K2. Our value for the mass function implies a primary mass of 1.5 +/- 0.3 Msun, somewhat lower than previous dynamical estimates, but consistent with the value found by analysis of type-I X-ray bursts from this system. Our Doppler tomography of the broad He II 4686 line reveals that most of the emission from this line is produced o...

  17. High-speed optical coherence tomography signal processing on GPU

    International Nuclear Information System (INIS)

    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).

  18. Parallel multithread computing for spectroscopic analysis in optical coherence tomography

    Science.gov (United States)

    Trojanowski, Michal; Kraszewski, Maciej; Strakowski, Marcin; Pluci?ski, Jerzy

    2014-05-01

    Spectroscopic Optical Coherence Tomography (SOCT) is an extension of Optical Coherence Tomography (OCT). It allows gathering spectroscopic information from individual scattering points inside the sample. It is based on time-frequency analysis of interferometric signals. Such analysis requires calculating hundreds of Fourier transforms while performing a single A-scan. Additionally, further processing of acquired spectroscopic information is needed. This significantly increases the time of required computations. During last years, application of graphical processing units (GPU's) was proposed to reduce computation time in OCT by using parallel computing algorithms. GPU technology can be also used to speed-up signal processing in SOCT. However, parallel algorithms used in classical OCT need to be revised because of different character of analyzed data. The classical OCT requires processing of long, independent interferometric signals for obtaining subsequent A-scans. The difference with SOCT is that it requires processing of multiple, shorter signals, which differ only in a small part of samples. We have developed new algorithms for parallel signal processing for usage in SOCT, implemented with NVIDIA CUDA (Compute Unified Device Architecture). We present details of the algorithms and performance tests for analyzing data from in-house SD-OCT system. We also give a brief discussion about usefulness of developed algorithm. Presented algorithms might be useful for researchers working on OCT, as they allow to reduce computation time and are step toward real-time signal processing of SOCT data.

  19. Macular optical coherence tomography findings following blunt ocular trauma

    Directory of Open Access Journals (Sweden)

    Oladiwura D

    2014-05-01

    Full Text Available Dilys Oladiwura,1 Lik Thai Lim,1 Elliott Yann Ah-kee,2 James Angus Scott31Tennent Institute of Ophthalmology, Gartnavel General Hospital (NHS Greater Glasgow and Clyde Trust, Glasgow, UK; 2University of Glasgow, Glasgow, UK; 3Falkirk Community Hospital (Forth Valley NHS Trust, Falkirk, UKAbstract: This case report describes the optical coherence tomography (OCT results of Berlin’s edema in a male subject following blunt ocular trauma from a soccer ball. A 27-year-old male presented with blurred vision in his left eye following blunt trauma. On admission, he underwent a complete eye examination and an OCT of the macula. Fundoscopy revealed commotio retinae, observed as an abnormal cream-colored discoloration of the fovea. The OCT showed outer photoreceptor segment disruption, retinal pigment epithelium inter-digitation, and intra-retinal edema of the outer nuclear layer. Following initial management, a repeat OCT after 3 months showed near complete resolution. OCT can be a useful adjunct for monitoring the progress of Berlin’s edema secondary to blunt ocular trauma because Berlin’s edema may present similarly clinically to other ocular trauma, but can affect different layers of the retina depending on the type of injury to the eye.Keywords: Berlin’s edema, commotio retinae, optical coherence tomography, OCT, ocular trauma

  20. Subluxed traumatic cataract: optical coherence tomography findings and clinical management

    Directory of Open Access Journals (Sweden)

    Kuriyan AE

    2012-12-01

    Full Text Available Ajay E Kuriyan, Harry W Flynn Jr, Sonia H YooDepartment of Ophthalmology, Bascom Palmer Eye Institute, University of Miami, Miami, FLAbstract: This case report describes the optical coherence tomography (OCT findings and clinical management of a patient with traumatic subluxed cataract. The patient presented with a traumatic subluxed cataract and vitreous prolapse into the anterior chamber. The anterior segment OCT showed vacuoles in the anterior subcapsular regions of the crystalline lens. The patient was treated with pars plana lensectomy, vitrectomy, and placement of an anterior chamber intraocular lens. The patient's best corrected visual acuity improved from hand motion at presentation to 20/25 during 3 years of follow-up. Anterior segment OCT demonstrates that the clinically visible vacuoles in traumatic cataract are located in the anterior subcapsular part of the lens. This is the first report in the literature using anterior segment OCT to visualize the subcapsular vacuolar changes in a traumatic cataract.Keywords: traumatic cataract, subluxed lens, vacuoles, anterior chamber intraocular lens, anterior segment optical coherence tomography

  1. Endoscopic optical coherence tomography for imaging the tympanic membrane

    Science.gov (United States)

    Burkhardt, Anke; Walther, Julia; Cimalla, Peter; Bornitz, Matthias; Koch, Edmund

    2011-06-01

    Optical coherence tomography (OCT) is an imaging modality that enables micrometer-scale contactless subsurface imaging of biological tissue. Endoscopy, as another imaging method, has the potential of imaging tubular organs and cavities and therefore has opened up several application areas not accessible before. The combination of OCT and endoscopy uses the advantages of both methods and consequently allows additional imaging of structures beneath surfaces inside cavities. Currently, visual investigations on the surface of the human tympanic membrane are possible but only with expert eyes. up to now, visual imaging of the outer ear up to the tympanic membrane can be carried out by an otoscope, an operating microscope or an endoscope. In contrast to these devices, endoscopy has the advantage of imaging the whole tympanic membrane with one view. The intention of this research is the development of an endoscopic optical coherence tomography (EOCT) device for imaging the tympanic membrane depth-resolved and structures behind it. Detection of fluids in the middle ear, which function as an indicator for otitis media, could help to avoid the application of antibiotics. It is possible to detect a congeries of fluids with the otoscope but the ambition is to the early detection by OCT. The developed scanner head allows imaging in working distances in the range from zero up to 5 mm with a field of view of 2 mm. In the next step, the scanner head should be improved to increase the working distance and the field of view.

  2. Optical coherence tomography for retinal imaging in multiple sclerosis

    Directory of Open Access Journals (Sweden)

    Zimmermann H

    2014-12-01

    Full Text Available Hanna Zimmermann,1 Timm Oberwahrenbrock,1 Alexander U Brandt,1 Friedemann Paul,1–3 Jan Dörr1,2 1NeuroCure Clinical Research Center, 2Clinical and Experimental Multiple Sclerosis Research Center, 3Department of Neurology, Charité – Universitätsmedizin Berlin, Berlin, Germany Abstract: Visual disturbances caused by inflammatory and demyelinating processes of the visual system, mainly in the optic nerve, are a common symptom in multiple sclerosis (MS. Optical coherence tomography (OCT is a tool that is increasingly used for quantifying retinal damage in MS and other neurologic diseases. Based on spectral interferometry, it uses low-coherent infrared light to generate high-resolution spatial images of the retina. The retinal nerve fiber layer (RNFL consists of unmyelinated axons that form the optic nerve, and thus represents a part of the central nervous system. OCT allows for noninvasive measurements of RNFL thickness in micrometer resolution. With the help of OCT, researchers have managed to demonstrate that eyes of MS patients show distinct RNFL thinning after an event of acute optic neuritis in MS, and even subclinical damage in eyes with no previous optic neuritis. OCT is also a useful tool in terms of providing a differential diagnosis of MS toward, for example, neuromyelitis optica, a disease that usually shows stronger retinal thinning, or Susac syndrome, which is characterized by distinct patchy thinning of the inner retinal layers. RNFL thinning is associated with magnetic resonance imaging-derived measurements of the brain, such as whole-brain atrophy, gray and white matter atrophy, and optic radiation damage. These features suggest that OCT-derived retinal measurements are a complement for measuring central nervous system neurodegeneration in the context of clinical trials – for example, with neuroprotective substances. Keywords: visual function, multiple sclerosis, optic neuritis, retinal nerve fiber layer, neuromyelitis optica, Susac syndrome

  3. Adaptive Optics Optical Coherence Tomography Based on a 61-Element Deformable Mirror

    International Nuclear Information System (INIS)

    When optical coherence tomography (OCT) is used to image human retina, its lateral resolution is deteriorated by the aberrations of the human eye. To get over this disadvantage, a high-resolution imaging system combining OCT with adaptive optics (AO) is being developed. The AO system consists of a 61-element deformable mirror and a 16x16 array Shack-Hartmann wave front sensor. In this paper, the configuration of the AO/OCT system is described, the simulation comparison among the 19-, 37- and 61-element adaptive optics systems and the experiment results for OCT with opened-loop AO are presented

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

    Science.gov (United States)

    Olivier, Scot S. (Livermore, CA); Werner, John S. (Davis, CA); Zawadzki, Robert J. (Sacramento, CA); Laut, Sophie P. (Pasedena, CA); Jones, Steven M. (Livermore, CA)

    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.

  5. Integrated modeling of the GMT laser tomography adaptive optics system

    Science.gov (United States)

    Piatrou, Piotr

    2014-08-01

    Laser Tomography Adaptive Optics (LTAO) is one of adaptive optics systems planned for the Giant Magellan Telescope (GMT). End-to-end simulation tools that are able to cope with the complexity and computational burden of the AO systems to be installed on the extremely large telescopes such as GMT prove to be an integral part of the GMT LTAO system development endeavors. SL95, the Fortran 95 Simulation Library, is one of the software tools successfully used for the LTAO system end-to-end simulations. The goal of SL95 project is to provide a complete set of generic, richly parameterized mathematical models for key elements of the segmented telescope wavefront control systems including both active and adaptive optics as well as the models for atmospheric turbulence, extended light sources like Laser Guide Stars (LGS), light propagation engines and closed-loop controllers. The library is implemented as a hierarchical collection of classes capable of mutual interaction, which allows one to assemble complex wavefront control system configurations with multiple interacting control channels. In this paper we demonstrate the SL95 capabilities by building an integrated end-to-end model of the GMT LTAO system with 7 control channels: LGS tomography with Adaptive Secondary and on-instrument deformable mirrors, tip-tilt and vibration control, LGS stabilization, LGS focus control, truth sensor-based dynamic noncommon path aberration rejection, pupil position control, SLODAR-like embedded turbulence profiler. The rich parameterization of the SL95 classes allows to build detailed error budgets propagating through the system multiple errors and perturbations such as turbulence-, telescope-, telescope misalignment-, segment phasing error-, non-common path-induced aberrations, sensor noises, deformable mirror-to-sensor mis-registration, vibration, temporal errors, etc. We will present a short description of the SL95 architecture, as well as the sample GMT LTAO system simulation results.

  6. Comparison of diffuse optical tomography of human breast with whole-body and breast-only positron emission tomography

    OpenAIRE

    Konecky, Soren D.; Choe, Regine; Corlu, Alper; Lee, Kijoon; Wiener, Rony; Srinivas, Shyam M.; Saffer, Janet R.; Freifelder, Richard; Karp, Joel S.; Hajjioui, Nassim; Azar, Fred; Yodh, Arjun G.

    2008-01-01

    We acquire and compare three-dimensional tomographic breast images of three females with suspicious masses using diffuse optical tomography (DOT) and positron emission tomography (PET). Co-registration of DOT and PET images was facilitated by a mutual information maximization algorithm. We also compared DOT and whole-body PET images of 14 patients with breast abnormalities. Positive correlations were found between total hemoglobin concentration and tissue scattering measured by DOT, and fluor...

  7. Determination of optical properties of oxidative bleaching human dental tissue samples using optical coherence tomography

    Science.gov (United States)

    Ni, Y. R.; Guo, Z. Y.; Shu, S. Y.; Zeng, C. C.; Zhong, H. Q.; Chen, B. L.; Liu, Z. M.; Bao, Y.

    2011-10-01

    Oxidative bleaching changes of human teeth induced changes in the optical properties of dental tissue. We introduced 1310 nm wavelengths of optical coherence tomography (OCT) attenuation coefficient method which is a relatively novel and rarely reported methodology to measure the correlation coefficient during the teeth oxidative bleaching procedure. And the quantitative parameters of enamel optical thickness and disruption of the entrance signal (DES) were extracted from the OCT images. The attenuation coefficient of the bleached tissue is 6.2 mm-1 which is significant (p attenuation coefficient varied significantly (p hydrogen peroxide-induced optical thickness of enamel is similar with unbleached tissue which may indicate the refractive index of enamel is unchanged. Moreover, disruption of the entrance signal (DES) analysis showed that remarkable difference was appeared at enamel surface. The results indicate that optical properties of oxidative bleaching human dental tissue can be determined by attenuation coefficient using OCT system.

  8. Spin state tomography of optically injected electrons in a semiconductor.

    Science.gov (United States)

    Kosaka, Hideo; Inagaki, Takahiro; Rikitake, Yoshiaki; Imamura, Hiroshi; Mitsumori, Yasuyoshi; Edamatsu, Keiichi

    2009-02-01

    Spin is a fundamental property of electrons, with an important role in information storage. For spin-based quantum information technology, preparation and read-out of the electron spin state are essential functions. Coherence of the spin state is a manifestation of its quantum nature, so both the preparation and read-out should be spin-coherent. However, the traditional spin measurement technique based on Kerr rotation, which measures spin population using the rotation of the reflected light polarization that is due to the magneto-optical Kerr effect, requires an extra step of spin manipulation or precession to infer the spin coherence. Here we describe a technique that generalizes the traditional Kerr rotation approach to enable us to measure the electron spin coherence directly without needing to manipulate the spin dynamics, which allows for a spin projection measurement on an arbitrary set of basis states. Because this technique enables spin state tomography, we call it tomographic Kerr rotation. We demonstrate that the polarization coherence of light is transferred to the spin coherence of electrons, and confirm this by applying the tomographic Kerr rotation method to semiconductor quantum wells with precessing and non-precessing electrons. Spin state transfer and tomography offers a tool for performing basis-independent preparation and read-out of a spin quantum state in a solid. PMID:19194446

  9. Approach to retina optical coherence tomography image processing

    Science.gov (United States)

    Yuan, Jiali; Liu, Ruihua; Xuan, Gao; Yang, Jun; Yuan, Libo

    2007-03-01

    Optical coherence tomography (OCT) is a recently developed imaging technology. By using Zeiss STRATUS OCT one could obtain clear tomography pictures of retina and macula lutea. The clinical use of image processing requires both medical knowledge and expertise in image processing techniques. This paper focused on processing of retina OCT image to design the automatic retina OCT image identification system that could help us evaluate retina, examine and clinically diagnose the fundus diseases. The motivation of our work is to extract the contour and highlight the feature area of the focus clearly and exactly. Generally it is related to image segmentation, enhancement and binarization etc. In the paper we try to reduce the image noise and make the symbolic area connected through color segmentation, low-pass filter and mathematical morphology algorithm etc., finally discern some common and different properties of postprocessing image compared with the real OCT image. Experiments were done on cystoid macular edema, macular hole and normal retina OCT image. The results show that the project raised is feasible and suitable for further image identification and classification according to ophthalmology criteria.

  10. Imaging thermally damaged tissue by Polarization Sensitive Optical Coherence Tomography.

    Science.gov (United States)

    De Boer, J; Srinivas, S; Malekafzali, A; Chen, Z; Nelson, J

    1998-09-14

    Polarization Sensitive Optical Coherence Tomography (PS- OCT) was used to image the reduction of birefringence in biological tissue due to thermal damage. Through simultaneous detection of the amplitude of signal fringes in orthogonal polarization states formed by interference of light backscattered from turbid media and a mirror in the reference arm of a Michelson interferometer, changes in the polarization due to the optical phase delay between light propagating along the fast and slow axes of birefringent media were measured. Inasmuch as fibrous structures in many biological tissues in uence the polarization state of light backscattered, PS-OCT is a potentially useful technique to image the structural properties of turbid biological materials. Birefringence of collagen, a constituent of many biological tissues, is reduced by denaturation that takes place at a temperature between 56-65 0 C, thus providing an "optical marker" for thermal damage. Images showing reduction of birefringence due to thermal damage in porcine tendon and skin are presented and demonstrate the potential of PS-OCT for burn depth assessment. PMID:19384363

  11. A combined reconstruction-classification method for diffuse optical tomography

    International Nuclear Information System (INIS)

    We present a combined classification and reconstruction algorithm for diffuse optical tomography (DOT). DOT is a nonlinear ill-posed inverse problem. Therefore, some regularization is needed. We present a mixture of Gaussians prior, which regularizes the DOT reconstruction step. During each iteration, the parameters of a mixture model are estimated. These associate each reconstructed pixel with one of several classes based on the current estimate of the optical parameters. This classification is exploited to form a new prior distribution to regularize the reconstruction step and update the optical parameters. The algorithm can be described as an iteration between an optimization scheme with zeroth-order variable mean and variance Tikhonov regularization and an expectation-maximization scheme for estimation of the model parameters. We describe the algorithm in a general Bayesian framework. Results from simulated test cases and phantom measurements show that the algorithm enhances the contrast of the reconstructed images with good spatial accuracy. The probabilistic classifications of each image contain only a few misclassified pixels.

  12. Optical diffraction tomography in an inhomogeneous background medium

    International Nuclear Information System (INIS)

    The filtered back-propagation algorithm (FBP algorithm) is a computationally fast and efficient inversion algorithm for reconstructing the 3D index of refraction distribution of weak scattering samples in free space from scattered field data collected in a set of coherent optical scattering experiments. This algorithm is readily derived using classical Fourier analysis applied to the Born or Rytov weak scattering models appropriate to scatterers embedded in a non-attenuating uniform background. In this paper, the inverse scattering problem for optical diffraction tomography (ODT) is formulated using the so-called distorted wave Born and Rytov approximations and a generalized version of the FBP algorithm is derived that applies to weakly scattering samples that are embedded in realistic, multiple scattering ODT experimental configurations. The new algorithms are based on the generalized linear inverse of the linear transformation relating the scattered field data to the complex index of refraction distribution of the scattering samples and are in the form of a superposition of filtered data, computationally back propagated into the ODT experimental configuration. The paper includes a computer simulation comparing the generalized Born and Rytov based FBP inversion algorithms as well as reconstructions generated using the generalized Born based FBP algorithm of a step index optical fiber from experimental ODT data

  13. 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.

  14. Clinical study of bladder diseases using optical coherence tomography

    Science.gov (United States)

    Zagainova, Elena; Gladkova, Natalia D.; Strelzova, O.; Sumin, A.; Gelikonov, Grigory V.; Feldchtein, Felix I.; Iksanov, Rashid R.

    2000-11-01

    Optical Coherence Tomography (OCT), a new optical bioimaging technique was used to evaluate the state of mucosa in the urinary bladder. The state of mucosa of the bladder was evaluated in patients with prostatic adenoma (11 male patients) during the course of prostatectomy operation via a resection cytoscope. An OCT probe was inserted into the biopsy channel of a cystoscope. The sites to be imaged by OCT were determined visually and, after OCT study, underwent excisional biopsy and subsequent histological examination. Children (9 girls) were examined during diagnostic cystoscopy. Our analysis of diagnostic capabilities of OCT in urology relies on the comparison of OCT information on normal and morphologically altered tissues. OCT is able to provide objective data concerning the structure of mucosa of the bladder due to the difference in optical properties of different layers in tissue. The epithelium and the layers of connective tissue, both in norm and pathology, are clearly visualized in the tomograms. Our OCT study of healthy mucosa of the urinary bladder has demonstrated that the epithelium appears in the tomograms as an upper highly backscattering layer. An underlying optically less transparent layer, much greater in size than the previous one, corresponds to the connective tissue of the mucosa. Inside this layer, elongated poorly backscattering formations with clear contours are seen; they do not alter the longitudinal structure of the submucosal layer. These formations are blood vessels. Optical patterns characteristic of chronic inflammation are obtained. They correspond, as confirmed histologically, to liquid accumulation, cellular infiltration of mucosal layers, hypervascularization, and fibrosis. OCT information on proliferative processes, such as papillomatosis of the urinary bladder and squamous cell carcinoma, is analyzed. It is shown that OCT can reliably reveal edema of the mucous membrane of the bladder and identify the character of appearing elements, such bulla, granule and polyp. OCT can provide information on the structure of tissue by characterizing its thickness and scattering properties.

  15. Fluorescence-enhanced optical tomography using phase information

    Science.gov (United States)

    Lu, Yujie; Sevick-Muraca, Eva M.

    2011-02-01

    Fluorescence-enhanced optical imaging/tomography (FEOI/FEOT) could play an important role in drug discovery and clinical diagnostics. In recent years, improvement in spatial resolution and quantitative biological information has been increasingly promised. Time- and frequency-resolved FEOT has great potential to obtain improved reconstruction information compared with continuous wave (CW) mode due to the acquisition of more measurement information. In this paper, a phase-only FEOT(PO-FEOT) is proposed and evaluated. In PO-FEOT, a finite element-based linear relationship between the unknown fluorophore variables and phase information obtained from time- and frequency-domain boundary measurements is used in FEOT reconstruction. Synthetic data shows that, compared to the amplitude and phase-based reconstruction, the reconstruction time cost is remarkably reduced when phase is used alone. The reconstructed results show that PO-FEOT with high frequency information can acquire preferable reconstruction quality.

  16. Fourier domain optical coherence tomography for high-precision profilometry

    Science.gov (United States)

    Lawman, Samuel; Liang, Haida

    2009-07-01

    A Fourier domain (FD) optical coherence tomography (OCT) system is shown to be capable of profilometry with two orders of magnitude better accuracy than the axial imaging resolution of the system. High precision OCT profilometry not only achieves similar accuracy as commercial white light interferometry based profilometers but is also capable of profilometry on complex subsurface structures with multiple interfaces of low reflectance. An accuracy of 55nm was achieved with a ThorLabs SROCT on a lab bench without special anti-vibration devices. This technique has the potential for a range of applications, such as high precision refractive index measurements and simultaneous dynamic monitoring of the interface structure of a drying varnish and the substrate.

  17. The Potential and Limitations of Intravascular Optical Coherence Tomography

    Directory of Open Access Journals (Sweden)

    N.D. Gladkova

    2012-12-01

    Full Text Available There has been analyzed the experience gained on optical coherence tomography (OCT application for diagnosis and control of arterial sclerotic disease. The principles of OCT-images acquisition have been described; there have been assessed the advantages and disadvantages of intravascular OCT devices used in clinical practice; and safety and the capabilities of intravascular OCT-procedure have been discussed. Great potential of intravascular OCT for understanding and management of arterial sclerotic disease has been demonstrated. There have been considered the possibilities of life-time diagnostics of a “vulnerable” atherosclerosis plaque, the determination of calcium and macrophages content in atherosclerosis plaque, as well as the features of coronarothrombosis. There has been brought to a sharper focus the role of intravascular OCT in stenting monitoring. The ways of improvement of intravascular OCT and its further development prospects have been presented.

  18. Imaging nanoparticle flow using magneto-motive optical Doppler tomography

    International Nuclear Information System (INIS)

    We introduce a novel approach for imaging solutions of superparamagnetic iron oxide (SPIO) nanoparticles using magneto-motive optical Doppler tomography (MM-ODT). MM-ODT combines an externally applied temporally oscillating high-strength magnetic field with ODT to detect nanoparticles flowing through a microfluidic channel. A solenoid with a cone-shaped ferrite core extensively increased the magnetic field strength (Bmax = 1 T, ?B2=220T2m-1) at the tip of the core and also focused the magnetic field in microfluidic channels containing nanoparticle solutions. Nanoparticle contrast was demonstrated in a microfluidic channel filled with an SPIO solution by imaging the Doppler frequency shift which was observed independently of the nanoparticle flow rate and direction. Results suggest that MM-ODT may be applied to image Doppler shift of SPIO nanoparticles in microfluidic flows with high contrast

  19. Implementation of an Optical Coherence Tomography system for painting characterization

    International Nuclear Information System (INIS)

    Optical Coherence Tomography (OCT) is a new but well established imaging technique for medical diagnosis, which can produce two- or three-dimensional images of bio-tissues with a few ?m spatial resolution. Its potential as a non-invasive tool for art conservation of paintings and other objects has been realized recently. In this work, we report the implementation of two OCT systems applied to painting characterization. One system operates in the so-called spectral domain, with a central wavelength of 840 nm and axial resolution of 10 ?m. The second system has its central wavelength at 1280 nm, with spatial resolution of 20 ?m, and operates in the time domain. Both systems are independently controlled and have imaging software developed in-house using Lab View. Using both systems, a 15 years old acrylic portrait has been analyzed, where the paint layers, light and dark colors, and the cotton treads of the canvas could be identified. (Author)

  20. Digital refocusing for transverse resolution improvement in optical coherence tomography

    International Nuclear Information System (INIS)

    Based on the fact that spectral domain (SD) optical coherence tomography (OCT) data can be treated as digital holography (DH) data acquired pointwise, we develop a spectral refocusing algorithm and show its ability to shift the focal region of OCT images obtained from SD OCT data acquired with a tightly focused scanning beam. Although refocusing itself depends on the refractive index of the studied media, we propose a procedure capable of restoring images with resolution equal to the resolution in the focal plane in the whole volume even in case of unknown refractive index of the media. As the proposed refocusing method operates with phases of the 3D Fourier spectrum of the SD OCT signal, it is very sensitive to the object motion during data acquisition. Thus, we also propose phase equalization preprocessing, which allows compensating the influence of such motions

  1. Evaluation of microfluidic channels with optical coherence tomography

    Science.gov (United States)

    Czajkowski, J.; Prykäri, T.; Alarousu, E.; Lauri, J.; Myllylä, R.

    2010-11-01

    Application of time domain, ultra high resolution optical coherence tomography (UHR-OCT) in evaluation of microfluidic channels is demonstrated. Presented study was done using experimental UHR-OCT device based on a Kerr-lens mode locked Ti:sapphire femtosecond laser, a photonic crystal fibre and modified, free-space Michelson interferometer. To show potential of the technique, microfluidic chip fabricated by VTT Center for Printed Intelligence (Oulu, Finland) was measured. Ability for full volumetric reconstruction in non-contact manner enabled complete characterization of closed entity of a microfluidic channel without contamination and harm for the sample. Measurement, occurring problems, and methods of postprocessing for raw data are described. Results present completely resolved physical structure of the channel, its spatial dimensions, draft angles and evaluation of lamination quality.

  2. Scalable multiplexing for parallel imaging with interleaved optical coherence tomography.

    Science.gov (United States)

    Lee, Hee Yoon; Marvdashti, Tahereh; Duan, Lian; Khan, Saara A; Ellerbee, Audrey K

    2014-09-01

    We demonstrate highly parallel imaging with interleaved optical coherence tomography (iOCT) using an in-house-fabricated, air-spaced virtually-imaged phased array (VIPA). The air-spaced VIPA performs spectral encoding of the interferograms from multiple lateral points within a single sweep of the source and allows us to tune and balance several imaging parameters: number of multiplexed points, ranging depth, and sensitivity. In addition to a thorough discussion of the parameters and operating principles of the VIPA, we experimentally demonstrate the effect of different VIPA designs on the multiplexing potential of iOCT. Using a 200-kHz light source, we achieve an effective A-scan rate of 3.2-MHz by multiplexing 16 lateral points onto a single wavelength sweep. The improved sensitivity of this system is demonstrated for 3D imaging of biological samples such as a human finger and a fruit fly. PMID:25401031

  3. Optical Coherence Tomography and Raman Spectroscopy of the retina

    Energy Technology Data Exchange (ETDEWEB)

    Evans, J W; Zawadzki, R J; Liu, R; Chan, J; Lane, S; Werner, J S

    2009-01-16

    Imaging the structure and correlating it with the biochemical content of the retina holds promise for fundamental research and for clinical applications. Optical coherence tomography (OCT) is commonly used to image the 3D structure of the retina and while the added functionality of biochemical analysis afforded by Raman scattering could provide critical molecular signatures for clinicians and researchers, there are many technical challenges to combining these imaging modalities. We present an ex vivo OCT microscope combined with Raman spectroscopy capable of collecting morphological and molecular information about a sample simultaneously. The combined instrument will be used to investigate remaining technical challenges to combine these imaging modalities, such as the laser power levels needed to achieve a Raman signal above the noise level without damaging the sample.

  4. Simplified approach to diffraction tomography in optical microscopy.

    Science.gov (United States)

    Fiolka, Reto; Wicker, Kai; Heintzmann, Rainer; Stemmer, Andreas

    2009-07-20

    We present a novel microscopy technique to measure the scattered wavefront emitted from an optically transparent microscopic object. The complex amplitude is decoded via phase stepping in a common-path interferometer, enabling high mechanical stability. We demonstrate theoretically and practically that the incoherent summation of multiple illumination directions into a single image increases the resolving power and facilitates image reconstruction in diffraction tomography. We propose a slice-by-slice object-scatter extraction algorithm entirely based in real space in combination with ordinary z-stepping. Thereby the computational complexity affiliated with tomographic methods is significantly reduced. Using the first order Born approximation for weakly scattering objects it is possible to obtain estimates of the scattering density from the exitwaves. PMID:19654642

  5. Algebraic reconstruction techniques for spectral reconstruction in diffuse optical tomography

    International Nuclear Information System (INIS)

    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

  6. Pre-seizure state identified by diffuse optical tomography

    Science.gov (United States)

    Zhang, Tao; Zhou, Junli; Jiang, Ruixin; Yang, Hao; Carney, Paul R.; Jiang, Huabei

    2014-01-01

    In epilepsy it has been challenging to detect early changes in brain activity that occurs prior to seizure onset and to map their origin and evolution for possible intervention. Here we demonstrate using a rat model of generalized epilepsy that diffuse optical tomography (DOT) provides a unique functional neuroimaging modality for noninvasively and continuously tracking such brain activities with high spatiotemporal resolution. We detected early hemodynamic responses with heterogeneous patterns, along with intracranial electroencephalogram gamma power changes, several minutes preceding the electroencephalographic seizure onset, supporting the presence of a ``pre-seizure'' state. We also observed the decoupling between local hemodynamic and neural activities. We found widespread hemodynamic changes evolving from local regions of the bilateral cortex and thalamus to the entire brain, indicating that the onset of generalized seizures may originate locally rather than diffusely. Together, these findings suggest DOT represents a powerful tool for mapping early seizure onset and propagation pathways.

  7. Quantitative comparison of analysis methods for spectroscopic optical coherence tomography

    Science.gov (United States)

    Bosschaart, Nienke; van Leeuwen, Ton G.; Aalders, Maurice C. G.; Faber, Dirk J.

    2013-01-01

    Spectroscopic optical coherence tomography (sOCT) enables the mapping of chromophore concentrations and image contrast enhancement in tissue. Acquisition of depth resolved spectra by sOCT requires analysis methods with optimal spectral/spatial resolution and spectral recovery. In this article, we quantitatively compare the available methods, i.e. the short time Fourier transform (STFT), wavelet transforms, the Wigner-Ville distribution and the dual window method through simulations in tissue-like media. We conclude that all methods suffer from the trade-off in spectral/spatial resolution, and that the STFT is the optimal method for the specific application of the localized quantification of hemoglobin concentration and oxygen saturation. PMID:24298417

  8. Investigation of anisotropic scattering for optical tomography in biological tissues

    International Nuclear Information System (INIS)

    Photons with wavelengths in near infrared region are used in optical tomography. Radiation transport theory should be preferred instead of diffusion theory for numerical modelling of photon migration in biological tissues, where diffusion theory is invalid. For example, diffusion theory is not sufficient in the regions of close to boundaries, sources or sinks and highly absorbing or void-like media. Also anisotropic scattering must be considered in the numerical models since scattering is generally highly anisotropic in biological tissues. In addition to the absorption and scattering coefficients, a suitable phase function must be known in anisotropic scattering study. Here we have compared scattering phase functions for anisotropy. Then we have calculated Legendre moments which are necessary for the implementation of anisotropy factors into the transport code, PARTISN. Discrete ordinates method (SN) has been used in the transport calculations. We have obtained solutions first a homogeneous and then heterogeneous medium.

  9. Dynamic diffuse optical tomography imaging of peripheral arterial disease.

    Science.gov (United States)

    Khalil, Michael A; Kim, Hyun K; Kim, In-Kyong; Flexman, Molly; Dayal, Rajeev; Shrikhande, Gautam; Hielscher, Andreas H

    2012-09-01

    Peripheral arterial disease (PAD) is the narrowing of arteries due to plaque accumulation in the vascular walls. This leads to insufficient blood supply to the extremities and can ultimately cause cell death. Currently available methods are ineffective in diagnosing PAD in patients with calcified arteries, such as those with diabetes. In this paper we investigate the potential of dynamic diffuse optical tomography (DDOT) as an alternative way to assess PAD in the lower extremities. DDOT is a non-invasive, non-ionizing imaging modality that uses near-infrared light to create spatio-temporal maps of oxy- and deoxy-hemoglobin in tissue. We present three case studies in which we used DDOT to visualize vascular perfusion of a healthy volunteer, a PAD patient and a diabetic PAD patient with calcified arteries. These preliminary results show significant differences in DDOT time-traces and images between all three cases, underscoring the potential of DDOT as a new diagnostic tool. PMID:23024920

  10. Image features of punctate inner choroiditis on optical coherence tomography

    Directory of Open Access Journals (Sweden)

    Hao Zhang

    2014-05-01

    Full Text Available AIM: To observe the image features of punctate inner choroiditis(PICat different stages by optical coherence tomography(OCT. METHODS: A retrospective analysis was performed on 24 PIC patients(33 eyeswith the median age of 29 years old(range: 16-47, where 19 cases were female(79.2%. Among the 24 cases, 9 cases were bilateral onset(37.5%and 19 cases were with myopia(79.2%. All of the patients were given fundus fluorescein angiography(FFAand optical coherence tomography(OCT. Through OCT, patients with PIC at different stages were observed for morphology of outer plexiform layer(OPLand outer nuclear layer(ONL, integrity of inside and outside connections of visual cells(IS/OS, integrity and morphology of reflective tape on retinal pigment epithelium(RPE, and light reflection intensity of choroid and sclera. RESULTS: The results showed that during active stage and atrophic stage of PIC, there were excavation of ONL and OPL towards thechoroid, weakened or partially disappeared reflective tape of IS/OS, interrupted or fuzzy reflective tape of RPE, hillock-like protrusion of RPE towards the ONL or ONL with medium to high reflection, and strengthened reflection of choroid and sclera under the lesion partly. The rates of the above performances in active stage were 9.1%, 100%, 100%, 86.4% and 77.3%, respectively, and in recovery stage, the corresponding rates were 81.8%, 90.1%, 81.8%, 45.5%, and 90.1%. Medium to high reflection of the protrusion under ONL was more commonly seen in active stage, with PPCONCLUSION: There are both common points and differences of OCT features in PIC at active stage and atrophic stage, suggesting the injury and repair pathological process of outer neural epithelium, retinal pigment epithelium and innerchoroid inflammatory.

  11. Optical tractography of the mouse heart using polarization-sensitive optical coherence tomography.

    Science.gov (United States)

    Wang, Yuanbo; Yao, Gang

    2013-01-01

    We developed a method to image myocardial fiber architecture in the mouse heart using a Jones matrix-based polarization-sensitive optical coherence tomography (PSOCT) system. The "cross-helical" laminar structure of myocardial fibers can be clearly visualized using this technology. The obtained myocardial fiber organization agrees well with existing knowledge acquired using conventional histology and diffusion tensor magnetic resonance imaging. PMID:24298414

  12. Scan-free optical correlation techniques: history and applications to optical coherence tomography

    International Nuclear Information System (INIS)

    In parallel with progress in generating ultrafast pulse sources and characterization techniques, optical time correlation techniques have seen tremendous development over many years and paved the way for novel applications in non-destructive and high resolution 'optical coherence tomography' (OCT) imaging. Amongst the known correlation techniques, the scan-free approach presents the advantage of single shot detection and real-time acquisition for pulse measurements, but this is not generally considered and applied for OCT imaging. The aim of this paper is to review the scan-free correlation method, analyze its performance and extended features and discuss its application to OCT. (review article)

  13. Construction of the Optical Delay Line for the Optical Coherence Tomography

    Directory of Open Access Journals (Sweden)

    Kitsakorn Locharoenrat

    2013-03-01

    Full Text Available We have constructed the compact optical delay line for the axial scanning of time-domain optical coherence tomography. The delay line contains the retro-reflector, and the inclined reflection mirror, as well as the scanning mirror. This delay line is performed by the low-coherence reflectometer with a scanning speed of 400 Hz. The dimension of the delay line is 2 cm × 2 cm. We have achieved the scanning range of about 3 mm within the scanning mirror’s vibration angle of approximately 10°

  14. Optical clearing of flowing blood using dextrans with spectral domain optical coherence tomography

    OpenAIRE

    Xu, Xiangqun; Yu, Lingfeng; Chen, Zhongping

    2008-01-01

    Spectral domain optical coherence tomography (SDOCT) images have been used to investigate the mechanism of optical clearing in flowing blood using dextrans. The depth reflectivity profiles from SDOCT indicate that dextrans become increasingly more effective in reducing scattering in flowing blood, except for 5 mgdl?1 of D×500, with increasing molecular weights (MW 70,000 and 500,000) and concentrations (0.6, 2, and 5 mgdl?1). Among the tested dextrans, D×500 at 2 mgdl?1 had the most s...

  15. Improving the quantitative accuracy of optical-emission computed tomography by incorporating an attenuation correction: application to HIF1 imaging

    OpenAIRE

    Kim, E.; Bowsher, J.; Thomas, A. S.; Sakhalkar, H.; Dewhirst, M.; Oldham, M.

    2008-01-01

    Optical computed tomography (optical-CT) and optical-emission computed tomography (optical-ECT) are new techniques for imaging the 3D structure and function (including gene expression) of whole unsectioned tissue samples. This work presents a method of improving the quantitative accuracy of optical-ECT by correcting for the ‘self’-attenuation of photons emitted within the sample. The correction is analogous to a method commonly applied in single-photon-emission computed tomography reconst...

  16. Application of optical coherence tomography to automated contact lens metrology

    Science.gov (United States)

    Davidson, Bryan R.; Barton, Jennifer K.

    2010-01-01

    Optical coherence tomography (OCT) is a nondestructive imaging modality with the potential to make quantitative spatial measurements. OCT's noncontact nature, sensitivity to small refractive index mismatches, and micron-scale resolution make it attractive for contact lens metrology, specifically, measuring prism. Prism is defined as the maximum difference in thickness of the contact lens, measured over a full 360 deg of rotation, at a fixed distance from the contact lens edge. We develop and test a novel algorithm that automatically analyzes OCT images and calculates prism. Images are obtained using a Thorlabs OCT930SR OCT system. The OCT probe is fastened to an automated rotation stage that rotates 360 deg in small increments (typically 10 deg) to acquire OCT images of the edge of the contact lens around the entire circumference. The images are 1.6 mm in optical depth (512 pixels) and 2 mm wide (1000 pixels). Several sets of images are successfully analyzed. The prism measured for a toric lens is 42 ?m, which is in line with design parameters. Thickness measurements are repeatable with a standard deviation of 0.5 ?m and maximum range of 1.8 ?m over ten image sets. This work demonstrates the possibility of using OCT to perform nondestructive contact lens metrology.

  17. Optical coherence tomography today: speed, contrast, and multimodality

    Science.gov (United States)

    Drexler, Wolfgang; Liu, Mengyang; Kumar, Abhishek; Kamali, Tschackad; Unterhuber, Angelika; Leitgeb, Rainer A.

    2014-07-01

    In the last 25 years, optical coherence tomography (OCT) has advanced to be one of the most innovative and most successful translational optical imaging techniques, achieving substantial economic impact as well as clinical acceptance. This is largely owing to the resolution improvements by a factor of 10 to the submicron regime and to the imaging speed increase by more than half a million times to more than 5 million A-scans per second, with the latter one accomplished by the state-of-the-art swept source laser technologies that are reviewed in this article. In addition, parallelization of OCT detection, such as line-field and full-field OCT, has shortened the acquisition time even further by establishing quasi-akinetic scanning. Besides the technical improvements, several functional and contrast-enhancing OCT applications have been investigated, among which the label-free angiography shows great potential for future studies. Finally, various multimodal imaging modalities with OCT incorporated are reviewed, in that these multimodal implementations can synergistically compensate for the fundamental limitations of OCT when it is used alone.

  18. Optical coherence tomography: imaging architect for dermal microdialysis in psoriasis

    Science.gov (United States)

    O'Connell, M.-L.; O'Connor, W.; Ramsay, B.; Guihen, E.; Ho, W. L.; Leahy, M. J.

    2011-03-01

    Optical coherence tomography (OCT) has been used as part of a ground breaking translational study to shed some light on one of the worlds most prevalent autoimmune diseases; psoriasis. The work successfully integrates the fields of optical imaging, biochemistry and dermatology in conducting a dermal microdialysis (DMD) trial for quantitative histamine assessment amongst a group of psoriasis sufferers. The DMD process involves temporary insertion of microscopic hollow tubes into a layer of skin to measure the levels of histamine and other important biological molecules in psoriasis. For comparison purposes, DMD catheters were implanted into healthy, peri-lesional and lesional skin regions. The catheters' entry and exit points and their precise locations in the epidermal layer of the skin were confirmed using OCT thus obtaining high resolution, wide-field images of the affected skin as well as catheter placement whilst local microdialysis enabled a tissue chemistry profile to be obtained from these three skin regions including histamine, a local immune system activator known to contribute towards itch and inflammation. Together these tools offer a synergistic approach in the clinical assessment of the disease. In addition, OCT delivered a non-invasive and rapid method for analyzing the affected skin architecture.

  19. Extended hierarchical Bayesian diffuse optical tomography for removing scalp artifact.

    Science.gov (United States)

    Shimokawa, Takeaki; Kosaka, Takashi; Yamashita, Okito; Hiroe, Nobuo; Amita, Takashi; Inoue, Yoshihiro; Sato, Masa-Aki

    2013-01-01

    Functional near-infrared spectroscopy (fNIRS) can non-invasively measure hemodynamic responses in the cerebral cortex with a portable apparatus. However, the observation signal in fNIRS measurements is contaminated by the artifact signal from the hemodynamic response in the scalp. In this paper, we propose a method to separate the signals from the cortex and the scalp by estimating both hemodynamic changes by diffuse optical tomography (DOT). In the inverse problem of DOT, we introduce smooth regularization to the hemodynamic change in the scalp and sparse regularization to that in the cortex based on the nature of the hemodynamic responses. These appropriate regularization models, with the spatial information of optical paths of many measurement channels, allow three-dimensional reconstruction of both hemodynamic changes. We validate our proposed method through two-layer phantom experiments and MRI-based head-model simulations. In both experiments, the proposed method simultaneously estimates the superficial smooth activity in the scalp area and the deep localized activity in the cortical area. PMID:24298404

  20. Lung vasculature imaging using speckle variance optical coherence tomography

    Science.gov (United States)

    Cua, Michelle; Lee, Anthony M. D.; Lane, Pierre M.; McWilliams, Annette; Shaipanich, Tawimas; MacAulay, Calum E.; Yang, Victor X. D.; Lam, Stephen

    2012-02-01

    Architectural changes in and remodeling of the bronchial and pulmonary vasculature are important pathways in diseases such as asthma, chronic obstructive pulmonary disease (COPD), and lung cancer. However, there is a lack of methods that can find and examine small bronchial vasculature in vivo. Structural lung airway imaging using optical coherence tomography (OCT) has previously been shown to be of great utility in examining bronchial lesions during lung cancer screening under the guidance of autofluorescence bronchoscopy. Using a fiber optic endoscopic OCT probe, we acquire OCT images from in vivo human subjects. The side-looking, circumferentially-scanning probe is inserted down the instrument channel of a standard bronchoscope and manually guided to the imaging location. Multiple images are collected with the probe spinning proximally at 100Hz. Due to friction, the distal end of the probe does not spin perfectly synchronous with the proximal end, resulting in non-uniform rotational distortion (NURD) of the images. First, we apply a correction algorithm to remove NURD. We then use a speckle variance algorithm to identify vasculature. The initial data show a vascaulture density in small human airways similar to what would be expected.

  1. Monte Carlo modeling of human tooth optical coherence tomography imaging

    International Nuclear Information System (INIS)

    We present a Monte Carlo model for optical coherence tomography (OCT) imaging of human tooth. The model is implemented by combining the simulation of a Gaussian beam with simulation for photon propagation in a two-layer human tooth model with non-parallel surfaces through a Monte Carlo method. The geometry and the optical parameters of the human tooth model are chosen on the basis of the experimental OCT images. The results show that the simulated OCT images are qualitatively consistent with the experimental ones. Using the model, we demonstrate the following: firstly, two types of photons contribute to the information of morphological features and noise in the OCT image of a human tooth, respectively. Secondly, the critical imaging depth of the tooth model is obtained, and it is found to decrease significantly with increasing mineral loss, simulated as different enamel scattering coefficients. Finally, the best focus position is located below and close to the dental surface by analysis of the effect of focus positions on the OCT signal and critical imaging depth. We anticipate that this modeling will become a powerful and accurate tool for a preliminary numerical study of the OCT technique on diseases of dental hard tissue in human teeth. (paper)

  2. Optimized doppler optical coherence tomography for choroidal capillary vasculature imaging

    Science.gov (United States)

    Liu, Gangjun; Qi, Wenjuan; Yu, Lingfeng; Chen, Zhongping

    2011-03-01

    In this paper, we analyzed the retinal and choroidal blood vasculature in the posterior segment of the human eye with optimized color Doppler and Doppler variance optical coherence tomography. Depth-resolved structure, color Doppler and Doppler variance images were compared. Blood vessels down to capillary level were able to be obtained with the optimized optical coherence color Doppler and Doppler variance method. For in-vivo imaging of human eyes, bulkmotion induced bulk phase must be identified and removed before using color Doppler method. It was found that the Doppler variance method is not sensitive to bulk motion and the method can be used without removing the bulk phase. A novel, simple and fast segmentation algorithm to indentify retinal pigment epithelium (RPE) was proposed and used to segment the retinal and choroidal layer. The algorithm was based on the detected OCT signal intensity difference between different layers. A spectrometer-based Fourier domain OCT system with a central wavelength of 890 nm and bandwidth of 150nm was used in this study. The 3-dimensional imaging volume contained 120 sequential two dimensional images with 2048 A-lines per image. The total imaging time was 12 seconds and the imaging area was 5x5 mm2.

  3. Characterization of tissue optical properties for prostate PDT using interstitial diffuse optical tomography

    Science.gov (United States)

    Liang, Xing; Wang, Ken Kang-hsin; Zhu, Timothy C.

    2012-02-01

    Photodynamic therapy (PDT) is an important treatment modality for localized diseases such as prostate cancer. In prostate PDT, light distribution is an important factor because it is directly related to treatment efficacy. During PDT, light distribution is determined by tissue optical property distributions (or heterogeneity). In this study, an interstitial diffuse optical tomography (iDOT) method was used to characterize optical properties in tissues. Optical properties (absorption and reduced scattering coefficients) of the prostate gland were reconstructed by solving the inverse problem using an adjoint model based on diffusion equation using a modified matlab public user code NIRFAST. In the modified NIRFAST method, linear sources were modeled for the reconstruction. Cross talking between absorption coefficients and reduced scattering coefficients were studied to have minimal effect, and a constrained optical property method (set either absorption coefficient or reduced scattering coefficient to be homogeneous) is also studied. A prostate phantom with optical anomalies was used to verify the iDOT method. The reconstructed results were compared with the known optical properties, and the spatial distribution of optical properties for this phantom was successfully reconstructed.

  4. Analysis of dental abfractions by optical coherence tomography

    Science.gov (United States)

    Demjan, Enikö; M?rc?u?eanu, Corina; Bratu, Dorin; Sinescu, Cosmin; Negru?iu, Meda; Ionita, Ciprian; Topal?, Florin; Hughes, Michael; Bradu, Adrian; Dobre, George; Podoleanu, Adrian Gh.

    2010-02-01

    Aim and objectives. Abfraction is the pathological loss of cervical hard tooth substance caused by biomechanical overload. High horizontal occlusal forces result in large stress concentrations in the cervical region of the teeth. These stresses may be high enough to cause microfractures in the dental hard tissues, eventually resulting in the loss of cervical enamel and dentin. The present study proposes the microstructural characterization of these cervical lesions by en face optical coherence tomography (eFOCT). Material and methods: 31 extracted bicuspids were investigated using eFOCT. 24 teeth derived from patients with active bruxism and occlusal interferences; they presented deep buccal abfractions and variable degrees of occlusal pathological attrition. The other 7 bicuspids were not exposed to occlusal overload and had a normal morphology of the dental crowns. The dental samples were investigated using an eFOCT system operating at 1300 nm (B-scan at 1 Hz and C-scan mode at 2 Hz). The system has a lateral resolution better than 5 ?m and a depth resolution of 9 ?m in tissue. OCT images were further compared with micro - computer tomography images. Results. The eFOCT investigation of bicuspids with a normal morphology revealed a homogeneous structure of the buccal cervical enamel. The C-scan and B-scan images obtained from the occlusal overloaded bicuspids visualized the wedge-shaped loss of cervical enamel and damage in the microstructure of the underlaying dentin. The high occlusal forces produced a characteristic pattern of large cracks, which reached the tooth surface. Conclusions: eFOCT is a promising imaging method for dental abfractions and it may offer some insight on the etiological mechanism of these noncarious cervical lesions.

  5. Computational aspects of endoscopic (trans-rectal) near-infrared optical tomography: initial investigations

    Science.gov (United States)

    Musgrove, Cameron; Bunting, Charles F.; Dehghani, Hamid; Pogue, Brian W.; Piao, Daqing

    2007-02-01

    Endoscopic near-infrared (NIR) optical tomography is a novel approach that allows the blood-based high intrinsic optical contrast to be imaged for the detection of cancer in internal organs. In endoscopic NIR tomography, the imaging array is arranged within the interior of the medium as opposed to the exterior as seen in conventional NIR tomography approaches. The source illuminates outward from the circular NIR probe, and the detector collects the diffused light from the medium surrounding the NIR probe. This new imaging geometry may involve forward and inverse approaches that are significantly different from those used in conventional NIR tomography. The implementation of a hollow-centered forward mesh within the context of conventional NIR tomography reconstruction has already led to the first demonstration of endoscopic NIR optical tomography. This paper presents some fundamental computational aspects regarding the performance and sensitivity of this endoscopic NIR tomography configuration. The NIRFAST modeling and image reconstruction package developed for conventional circular NIR geometry is used for endoscopic NIR tomography, and initial quantitative analysis has been conducted to investigate the "effective" imaging depth, required mesh resolution, and limit in contrast resolution, among other parameters. This study will define the performance expected and may provide insights into hardware requirements needed for revision of NIRFAST for the endoscopic NIR tomography geometry.

  6. Intra- and Inter-Frame Differential Doppler Optical Coherence Tomography

    Directory of Open Access Journals (Sweden)

    Tilman Schmoll

    2015-03-01

    Full Text Available Spectrometer based optical coherence tomography suffers from fringe washout for fast flow, a drawback for flow visualization, which is of interest for both lable-free optical angiography and flow quantification. We presented a method, which can be used to contrast very fast flows, while maintaining relatively low A-scan rates. It is based on introducing a phase shift of ? during acquisition such that the interference fringes associated to moving sample structures are recovered depending on the axial velocity. This enables the use of slower line scan cameras for measuring the fast blood flows within the large vessels in the region of the optic nerve head, while keeping good sensitivity. Furthermore it can be used to contrast the fast moving structures by attenuating the static and slower moving tissue signals. A drawback is still the narrow velocity bandwidth, which is not optimal for providing optical angiography for the full vascular plexus. Nevertheless, it could be of value for following fast dynamic changes, as for example in optical elastography. We introduce different variants of this method, based on intra-frame phase switching, as well as between consecutive A-scans and B-scans, which are then pairwise summed. A phase shift of ? between summed scans is in fact equivalent to subtraction of both in general complex valued scans. Analyzing complex signal differences between successive B-scans allows in particular contrasting very slow flows of the capillary network. After setting the theoretical framework we show proof-of-principle measurements with a piezo mirror, as well as in vivo measurements of the human retina for the different intra-frame phase shifting schemes. We further show the capability to contrast the parafoveal capillary structure with the differential inter B-scan method and discuss its limitations. Improvement of the sensitivity might be achieved by increasing the number of B-scans to be used for calculating the signal differences, as well as by increasing the sampling density. Care must then be taken for in vivo imaging to keep the total measurement time still sufficiently small, typically a few seconds. The method may proof as a valuable diagnostic tool, as several retinal diseases will manifest at an early stage in capillary disorders.

  7. Choroidal thinning in high myopia measured by optical coherence tomography

    Directory of Open Access Journals (Sweden)

    Ikuno Y

    2013-05-01

    Full Text Available Yasushi Ikuno, Satoko Fujimoto, Yukari Jo, Tomoko Asai, Kohji NishidaDepartment of Ophthalmology, Osaka University Graduate School of Medicine, Osaka, JapanPurpose: To investigate the rate of choroidal thinning in highly myopic eyes.Patients and methods: A retrospective observational study of 37 eyes of 26 subjects (nine males and 17 females, mean age 39.6 ± 7.7 years with high myopia but no pathologies who had undergone spectral domain optical coherence tomography and repeated the test 1 year later (1 ± 0.25 year at Osaka University Hospital, Osaka, Japan. Patients older than 50 years with visual acuity worse than 20/40 or with whitish chorioretinal atrophy involving the macula were excluded. Two masked raters measured the choroidal thicknesses (CTs at the foveda, 3 mm superiorly, inferiorly, temporally, and nasally on the images and averaged the values. The second examination was about 365 days after the baseline examination. The CT reduction per year (CTRPY was defined as (CT 1 year after - baseline CT/days between the two examinations × 365. The retinal thicknesses were also investigated.Results: The CTRPY at the fovea was ?1.0 ± 22.0 µm (range –50.2 to 98.5 at the fovea, –6.5 ± 24.3 µm (range ?65.8 to 90.2 temporally, –0.5 ± 22.3 µm (range –27.1 to 82.5 nasally, –9.7 ± 21.7 µm (range –40.1 to 60.1 superiorly, and –1.4 ± 25.5 µm (range –85.6 to 75.2 inferiorly. There were no significant differences in the CTRPY at each location (P = 0.34. The CT decreased significantly (P < 0.05 only superiorly. The superior CTRPY was negatively correlated with the axial length (P < 0.05. The retinal thickness at the fovea did not change. Stepwise analysis for CTRPY selected axial length (P = 0.04, R2 = 0.13 and age (P = 0.08, R2 = 0.21 as relevant factors.Conclusions: The highly myopic choroid might gradually thin and be affected by many factors. Location and axial length are key factors to regulate the rate of choroidal thinning in highly myopic eyes. Overall choroidal thickness was not found to change significantly. Longer follow-ups are needed.Keywords: high myopia, choroid, optical coherence tomography, age

  8. Compact MEMS-based Adaptive Optics Optical Coherence Tomography for Clinical Use

    Energy Technology Data Exchange (ETDEWEB)

    Chen, D; Olivier, S; Jones, S; Zawadzki, R; Evans, J; Choi, S; Werner, J

    2008-02-04

    We describe a compact MEMS-based adaptive optics (AO) optical coherence tomography system with improved AO performance and ease of clinical use. A typical AO system consists of a Shack-Hartmann wavefront sensor and a deformable mirror that measures and corrects the ocular and system aberrations. Because of the limitation on the current deformable mirror technologies, the amount of real-time ocular-aberration compensation is restricted and small in the previous AO-OCT instruments. In this instrument, we proposed to add an optical apparatus to correct the spectacle aberrations of the patients such as myopia, hyperopia and astigmatism. This eliminated the tedious process of the trial lenses in clinical imaging. Different amount of spectacle aberration compensation was achieved by motorized stages and automated with the AO computer for ease of clinical use. In addition, the compact AO-OCT was optimized to have minimum system aberrations to reduce AO registration errors and improve AO performance.

  9. Wavefront sensorless adaptive optics optical coherence tomography for in vivo retinal imaging in mice.

    Science.gov (United States)

    Jian, Yifan; Xu, Jing; Gradowski, Martin A; Bonora, Stefano; Zawadzki, Robert J; Sarunic, Marinko V

    2014-02-01

    We present wavefront sensorless adaptive optics (WSAO) Fourier domain optical coherence tomography (FD-OCT) for in vivo small animal retinal imaging. WSAO is attractive especially for mouse retinal imaging because it simplifies optical design and eliminates the need for wavefront sensing, which is difficult in the small animal eye. GPU accelerated processing of the OCT data permitted real-time extraction of image quality metrics (intensity) for arbitrarily selected retinal layers to be optimized. Modal control of a commercially available segmented deformable mirror (IrisAO Inc.) provided rapid convergence using a sequential search algorithm. Image quality improvements with WSAO OCT are presented for both pigmented and albino mouse retinal data, acquired in vivo. PMID:24575347

  10. [Optic disc drusen. Communication 3. The possibilities of optic coherence tomography].

    Science.gov (United States)

    Sheremet, N L; Galoian, N S; Kazarian, E E; Kiseleva, T N; Kravchuk, E A; Kharlap, S I

    2010-01-01

    Twenty-six patients (45 eyes) (median age 55 years) with optic disc drusen (ODD) (a study group) and 24 healthy volunteers (47 eyes) (median age 53 years) (a control group) were examined. Nerve fiber layer thinning determined by optic coherence tomography (OCT) was found in 65% of the ODD. In 20% of the patients with ODD, nerve fiber layer thinning, as evidenced by OCT, was observed with the normal field of vision, which suggests the higher sensitivity of a morphometric study of the retinal nerve fiber layer. According to OCT data, 11% of the patients with pathological changes in the field of vision had increased retinal nerve fiber layer thickness in some quadrants or from the mean value. These changes may be associated with the large-sized optic disc in these patients. PMID:21105372

  11. Optically buffered Jones-matrix-based multifunctional optical coherence tomography with polarization mode dispersion correction

    Science.gov (United States)

    Hong, Young-Joo; Makita, Shuichi; Sugiyama, Satoshi; Yasuno, Yoshiaki

    2014-01-01

    Polarization mode dispersion (PMD) degrades the performance of Jones-matrix-based polarization-sensitive multifunctional optical coherence tomography (JM-OCT). The problem is specially acute for optically buffered JM-OCT, because the long fiber in the optical buffering module induces a large amount of PMD. This paper aims at presenting a method to correct the effect of PMD in JM-OCT. We first mathematically model the PMD in JM-OCT and then derive a method to correct the PMD. This method is a combination of simple hardware modification and subsequent software correction. The hardware modification is introduction of two polarizers which transform the PMD into global complex modulation of Jones matrix. Subsequently, the software correction demodulates the global modulation. The method is validated with an experimentally obtained point spread function with a mirror sample, as well as by in vivo measurement of a human retina. PMID:25657888

  12. Optimization of image-forming optics for transmission optical projection tomography

    Science.gov (United States)

    Wang, Yi; Wang, Ruikang K.

    2007-09-01

    A new optical system for transmission optical projection tomography (TOPT) is presented to reduce the divergence of the projection data from the true parallel projections. This is performed by introducing an iris at the back focus of the objective lens. The influence of the defocusing on TOPT is demonstrated by computational simulations and experiments. We compare the performances of the new and conventional TOPT systems in order to optimize the optical system for three-dimensional imaging of the embryos of small animals. The optimal imaging performance is given by the new system with numerical apertures between 0.007 and 0.014, with which the spatial resolution of 25 ?m is achieved. The optimal configuration is validated by TOPT of a phantom sample and a fixed five-day chick embryo.

  13. Detection of Cystoid Macular Edema with Three-Dimensional Optical Coherence Tomography versus Fluorescein Angiography

    OpenAIRE

    Ouyang, Yanling; Keane, Pearse A.; Sadda, Srinivas R.; Walsh, Alexander C.

    2010-01-01

    This study was a comparison of the sensitivity and reproducibility of three-dimensional optical coherence tomography (3D-OCT) and fluorescein angiography (FA) for the detection of cystoid macular edema (CME).

  14. On the Convergence of the Born Series in Optical Tomography with Diffuse Light

    CERN Document Server

    Markel, V A; Markel, Vadim A.; Schotland, John C.

    2007-01-01

    We provide a simple sufficient condition for convergence of Born series in the forward problem of optical diffusion tomography. The condition does not depend on the shape or spatial extent of the inhomogeneity but only on its amplitude.

  15. Predicting tumor response in breast cancer patients using diffuse optical tomography

    Science.gov (United States)

    Gunther, Jacqueline E.; Lim, Emerson; Kim, Hyun Keol; Flexman, Molly; Refice, Susan; Brown, Mindy; Kalinsky, Kevin; Hershman, Dawn; Hielscher, Andreas H.

    2013-06-01

    We have developed a diffuse optical tomography imaging system to track breast tumor progression in patients undergoing neoadjuvant chemotherapy. Preliminary results have shown that tumor response can be predicted by the second week of treatment.

  16. Reproducibility of Spectral-Domain Optical Coherence Tomography Total Retinal Thickness Measurements in Mice

    OpenAIRE

    Gabriele, Michelle L.; Ishikawa, Hiroshi; Schuman, Joel S.; Bilonick, Richard A.; Kim, Jongsick; Kagemann, Larry; Wollstein, Gadi

    2010-01-01

    The reproducibility of mouse retinal thickness measurements, obtained with volumetric spectral-domain optical coherence tomography (SD-OCT) was evaluated. Good reproducibility may make SD-OCT valuable for further studies in mice.

  17. 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

  18. Advances of full-field optical coherence tomography (FFOCT) for clinical applications and developmental biology

    OpenAIRE

    Burcheri-curatolo, Adriano

    2012-01-01

    Optical coherence tomography (OCT) is now an established technique for visualizing the internal morphology of the eye. In the last decade, the aim has been to achieve similar results in highly scattering tissues. One limitation of previous studies with OCT has been the low resolution compared to the gold standard of histology. Full-field optical coherence tomography (FFOCT), a variant of OCT also based on low-coherence interferometry, generates micron-scale images over a large field of view b...

  19. Automated segmentation of intramacular layers in Fourier domain optical coherence tomography structural images from normal subjects

    OpenAIRE

    Zhang, Xusheng; Yousefi, Siavash; An, Lin; Wang, Ruikang K.

    2012-01-01

    Segmentation of optical coherence tomography (OCT) cross-sectional structural images is important for assisting ophthalmologists in clinical decision making in terms of both diagnosis and treatment. We present an automatic approach for segmenting intramacular layers in Fourier domain optical coherence tomography (FD-OCT) images using a searching strategy based on locally weighted gradient extrema, coupled with an error-removing technique based on statistical error estimation. A two-step denoi...

  20. Optical coherence tomography under general anesthesia in a child with nystagmus.

    OpenAIRE

    Sony, P.; Chandra, P.; Azad, Rv

    2004-01-01

    PURPOSE: To describe a method that permits optical coherence tomography scanning to be performed under general anesthesia. DESIGN: Observational case report. METHODS: A 7-year-old child underwent optical coherence tomography scanning under general anesthesia. He was positioned prone, with the neck extended to enable vertical facial alignment on the scanner. An anti-Trendelenburg trend on the operating table minimized the degree of neck extension required. Intravenous fluids, modest ventilator...

  1. Spectral-domain optical coherence tomography and fundus autofluorescence evaluation of torpedo maculopathy.

    Science.gov (United States)

    Thomas, Akshay S; Flaxel, Christina J; Pennesi, Mark E

    2015-01-01

    The authors describe the spectral-domain optical coherence tomography and fundus autofluorescence findings in a case of torpedo maculopathy. Spectral-domain optical coherence tomography revealed loss or disruption of the retinal pigment epithelium and overlying disruption of the outer neurosensory retina. Fundus autofluorescence revealed reduced fundus autofluorescence of the lesion surrounded by a rim of increased fundus autofluorescence. [J Pediatr Ophthalmol Strabismus. 2015;52:e8-e10.]. PMID:25751084

  2. Spectral Doppler optical coherence tomography imaging of localized ischemic stroke in a mouse model

    OpenAIRE

    Yu, Lingfeng; Nguyen, Elaine; Liu, Gangjun; Choi, Bernard; Chen, Zhongping

    2010-01-01

    We report the use of spectral Doppler optical coherence tomography imaging (SDOCTI) for quantitative evaluation of dynamic blood circulation before and after a localized ischemic stroke in a mouse model. Rose Bengal photodynamic therapy (PDT) is used as a noninvasive means for inducing localized ischemia in cortical microvasculature of the mouse. Fast, repeated Doppler optical coherence tomography scans across vessels of interest are performed to record flow dynamic information with high temp...

  3. Comparison of diffuse optical tomography of human breast with whole-body and breast-only positron emission tomography.

    Science.gov (United States)

    Konecky, Soren D; Choe, Regine; Corlu, Alper; Lee, Kijoon; Wiener, Rony; Srinivas, Shyam M; Saffer, Janet R; Freifelder, Richard; Karp, Joel S; Hajjioui, Nassim; Azar, Fred; Yodh, Arjun G

    2008-02-01

    We acquire and compare three-dimensional tomographic breast images of three females with suspicious masses using diffuse optical tomography (DOT) and positron emission tomography (PET). Co-registration of DOT and PET images was facilitated by a mutual information maximization algorithm. We also compared DOT and whole-body PET images of 14 patients with breast abnormalities. Positive correlations were found between total hemoglobin concentration and tissue scattering measured by DOT, and fluorodeoxyglucose (18F-FDG) uptake. In light of these observations, we suggest potential benefits of combining both PET and DOT for characterization of breast lesions. PMID:18383664

  4. Detection of atherosclerotic vascular tissue from optical coherence tomography images

    Science.gov (United States)

    Prakash, Ammu; Hewko, Mark; Sowa, Mike; Sherif, Sherif

    2012-10-01

    Atherosclerotic coronary artery disease continues to be one of the major causes of mortality. Prevention, diagnosis and treatment of atherosclerotic coronary artery disease are dependent on the detection of high risk atherosclerotic plaque. As age is one of the most important risk factors, atherosclerosis worsens steadily with increasing age. Automatic characterization of atherosclerotic plaque using the optical coherence tomography (OCT) images provides a powerful tool to classify patients with high risk plaque. In this study we develop an automatic classifier to detect atherosclerotic plaque in young and old Watanabe heritable hyperlipidemic (WHHL) rabbits, using OCT images without reliance on visual inspection. Our classifier based on texture analysis technique may provide an efficient tool for detecting invisible changes in tissue structure. We extracted a set of 22 statistical textural features for each image using the spatial gray level dependence matrix (SGLDM) method. An optimal scalar feature selection process was carried to select the best discriminating features that employ the Fisher discriminant ratio (FDR) criterion, and cross correlation measure between the pairs of features. Using these optimal features, we formed a combination of 5 best classification features using an exhaustive search method. A combined feature set was finally employed for the classification of plaque. We obtained correct classification rate and validation of 76.67% and 75% respectively.

  5. Determination of dental decay rates with optical coherence tomography

    Science.gov (United States)

    Freitas, A. Z.; Zezell, D. M.; Mayer, M. P. A.; Ribeiro, A. C.; Gomes, A. S. L.; Vieira, N. D., Jr.

    2009-12-01

    We report the use of optical coherence tomography (OCT) to detect and quantify demineralization process induced by S. mutans biofilm in third molars human teeth. Artificial lesions were induced by a S. mutans microbiological culture and the samples (N = 50) were divided into groups according to the demineralization time: 3, 5, 7, 9, and 11 days. The OCT system was implemented using a light source delivering an average power of 96 ?W in the sample arm, and spectral characteristics allowing 23 ?m of axial resolution. The images were produced with lateral scans step of 10 ?m and analyzed individually. As a result of the evaluation of theses images, lesion depth was calculated as function of demineralization time. The depth of the lesion in the root dentine increased from 70 ?m to 230 ?m (corrected by the enamel refraction index, 1.62 @ 856 nm), depending of exposure time. The lesion depth in root dentine was correlated to demineralization time, showing that it follows a geometrical progression like a bacteria growth law.

  6. Retinal and choroidal intravascular spectral-domain optical coherence tomography

    DEFF Research Database (Denmark)

    Willerslev, Anne; Li, Xiao Q

    2013-01-01

    Purpose:? To examine retinal and choroidal blood vessels using spectral-domain optical coherence tomography (SD-OCT). Methods:? Retrospective case series. Results:? Scans through retinal blood vessels in healthy subjects demonstrated vessel wall reflexes and a tri-layer profile of the blood column on longitudinal scans and a figure-of-eight configuration on cross-sectional scans. Intravascular reflectivity decreased with increasingly oblique angles of observation and was absent when blood flow was parallel to the line of sight. The high blood flow in the choroidal vessels in healthy subjects and the low flow in the retinal vessels in patients with ocular ischaemic syndrome and central retinal artery occlusion were both associated with lower reflectivity of the blood and an unstructured intravascular SD-OCT profile. Discussion:? This qualitative in vivo study found a characteristically structured SD-OCT profile of the blood column in retinal vessels with normal blood flow. Both structure and total reflectivityfaded when blood flow was lower or higher than normal or at oblique angles to the line of sight. In conclusion, SD-OCT scans of the vessels in the posterior pole of the eye may assist the clinical assessment of gross abnormalities of ocular blood flow, e.g. in carotid artery stenosis.

  7. OCT y fototoxicidad macular / Optical coherence tomography and macular phototoxicity

    Scientific Electronic Library Online (English)

    N.A., Rodríguez-Marco; J., Andonegui-Navarro; E., Compains-Silva; A., Rebollo-Aguayo; D., Aliseda-Pérez-de-Madrid; M., Aranguren-Laflin.

    2008-04-01

    Full Text Available SciELO Spain | Language: Spanish Abstract in spanish Caso clínico: Se realiza una exploración ocular y tomografía de coherencia óptica (OCT) en tres pacientes con lesiones fototóxicas retinianas. Las angiografías fluoresceínicas muestran un defecto ventana. La OCT muestra hiporreflectividad en la porción externa de la fóvea y fragmentación de las capa [...] s más internas entre la porción interna de los fotorreceptores y los segmentos externos. Discusión: Las lesiones retinianas tras exposición a la luz aparecen precozmente mostrando diferentes patrones en la OCT. La OCT sugiere que la disminución de visión asocia una lesión de fotorreceptores y epitelio pigmentario retiniano (EPR). La OCT es útil para objetivar la retinopatía fototóxica donde los cambios oftalmoscópicos pueden estar ausentes o ser mínimos. Abstract in english Case report: Ocular examinations and optical coherence tomography (OCT) were performed in three patients with retinal phototoxicity lesions. Fluorescein angiography depicted a window defect. OCT exhibited hyporeflectivity at the outer foveal retina and fragmentation of the inner reflective layers, c [...] orresponding to the junction between the inner and outer photoreceptor segments. Discussion: Retinal damage after light exposure has a rapid onset and shows different patterns in OCT examination. OCT findings suggest that decreased visual acuity may be associated with full-thickness photoreceptors and retinal pigment epithelium (RPE) involvement. OCT is a useful tool for objective assessment of retinal pathology in phototoxicity cases where fundus changes may be minimal or absent.

  8. OCT y fototoxicidad macular Optical coherence tomography and macular phototoxicity

    Directory of Open Access Journals (Sweden)

    N.A. Rodríguez-Marco

    2008-04-01

    Full Text Available Caso clínico: Se realiza una exploración ocular y tomografía de coherencia óptica (OCT en tres pacientes con lesiones fototóxicas retinianas. Las angiografías fluoresceínicas muestran un defecto ventana. La OCT muestra hiporreflectividad en la porción externa de la fóvea y fragmentación de las capas más internas entre la porción interna de los fotorreceptores y los segmentos externos. Discusión: Las lesiones retinianas tras exposición a la luz aparecen precozmente mostrando diferentes patrones en la OCT. La OCT sugiere que la disminución de visión asocia una lesión de fotorreceptores y epitelio pigmentario retiniano (EPR. La OCT es útil para objetivar la retinopatía fototóxica donde los cambios oftalmoscópicos pueden estar ausentes o ser mínimos.Case report: Ocular examinations and optical coherence tomography (OCT were performed in three patients with retinal phototoxicity lesions. Fluorescein angiography depicted a window defect. OCT exhibited hyporeflectivity at the outer foveal retina and fragmentation of the inner reflective layers, corresponding to the junction between the inner and outer photoreceptor segments. Discussion: Retinal damage after light exposure has a rapid onset and shows different patterns in OCT examination. OCT findings suggest that decreased visual acuity may be associated with full-thickness photoreceptors and retinal pigment epithelium (RPE involvement. OCT is a useful tool for objective assessment of retinal pathology in phototoxicity cases where fundus changes may be minimal or absent.

  9. Optical coherence tomography for imaging of skin and skin diseases

    DEFF Research Database (Denmark)

    Mogensen, Mette; Thrane, Lars

    2009-01-01

    Optical coherence tomography (OCT) is an emerging imaging technology based on light reflection. It provides real-time images with up to 2-mm penetration into the skin and a resolution of approximately 10 ?m. It is routinely used in ophthalmology. The normal skin and its appendages have been studied, as have many diseases. The method can provide accurate measures of epidermal and nail changes in normal tissue. Skin cancer and other tumors, as well as inflammatory diseases, have been studied and good agreement found between OCT images and histopathological architecture. OCT also allows noninvasive monitoring of morphologic changes in skin diseases and may have a particular role in the monitoring of medical treatment of nonmelanoma skin cancer. The technology is however still evolving and continued technological development will necessitate an ongoing evaluation of its diagnostic accuracy. Several technical solutions are being pursued to further improve the quality of the images and the data provided, and OCT isbeing integrated in multimodal imaging devices that would potentially be able to provide a quantum leap to the imaging of skin in vivo.

  10. Ultrahigh speed endoscopic optical coherence tomography for gastroenterology.

    Science.gov (United States)

    Tsai, Tsung-Han; Lee, Hsiang-Chieh; Ahsen, Osman O; Liang, Kaicheng; Giacomelli, Michael G; Potsaid, Benjamin M; Tao, Yuankai K; Jayaraman, Vijaysekhar; Figueiredo, Marisa; Huang, Qin; Cable, Alex E; Fujimoto, James; Mashimo, Hiroshi

    2014-12-01

    We describe an ultrahigh speed endoscopic swept source optical coherence tomography (OCT) system for clinical gastroenterology using a vertical-cavity surface-emitting laser (VCSEL) and micromotor imaging catheter. The system had a 600 kHz axial scan rate and 8 µm axial resolution in tissue. Imaging was performed with a 3.2 mm diameter imaging catheter at 400 frames per second with a 12 µm spot size. Three-dimensional OCT (3D-OCT) imaging was performed in patients with a cross section of pathologies undergoing upper and lower endoscopy. The use of distally actuated imaging catheters enabled OCT imaging with more flexibility, such as volumetric imaging in the small intestine and the assessment of hiatal hernia using retroflex imaging. The high rotational scanning stability of the micromotor enabled 3D volumetric imaging with micron scale volumetric accuracy for both en face OCT and cross-sectional imaging, as well as OCT angiography (OCTA) for 3D visualization of subsurface microvasculature. The ability to perform both structural and functional 3D OCT imaging in the GI tract with microscopic accuracy should enable a wide range of studies and enhance the sensitivity and specificity of OCT for detecting pathology. PMID:25574446

  11. Non-Harmonic Analysis Applied to Optical Coherence Tomography Imaging

    Science.gov (United States)

    Cao, Xu; Uchida, Tetsuya; Hirobayashi, Shigeki; Chong, Changho; Morosawa, Atsushi; Totsuka, Koki; Suzuki, Takuya

    2012-02-01

    A new processing technique called non-harmonic analysis (NHA) is proposed for optical coherence tomography (OCT) imaging. Conventional Fourier-domain OCT employs the discrete Fourier transform (DFT), which depends on the window function and length. The axial resolution of the OCT image, calculated by using DFT, is inversely proportional to the full width at half maximum (FWHM) of the wavelength range. The FWHM of wavelength range is limited by the sweeping range of the source in swept-source OCT and it is limited by the number of CCD pixels in spectral-domain OCT. However, the NHA process does not have such constraints; NHA can resolve high frequencies irrespective of the window function and the frame length of the sampled data. In this study, the NHA process is described and it is applied to OCT imaging. It is compared with OCT images based on the DFT. To demonstrate the benefits of using NHA for OCT, we perform OCT imaging with NHA of an onion skin. The results reveal that NHA can achieve an image resolution equivalent that of a 100-nm sweep range using a significantly reduced wavelength range. They also reveal the potential of using this technique to achieve high-resolution imaging without using a broadband source. However, the long calculation times required for NHA must be addressed if it is to be used in clinical applications.

  12. Imaging cutaneous T-Cell lymphoma with optical coherence tomography

    DEFF Research Database (Denmark)

    Ring, H.C.; Hansen Stamp, I.M.

    2012-01-01

    Aim: To investigate the presentation of a patch-stage cutaneous T-cell lymphoma (CTCL) using optical coherence tomography (OCT). Methods: A patient with a patch caused by CTCL was photographed digitally, OCT-scanned and biopsied. A normal skin area adjacent to the patch was OCT-scanned for comparison, but not biopsied. The OCT image and the histological image were compared. Results: The OCT images illustrated a thickened and hyperreflective stratum corneum. OCT also demonstrated several elongated hyporeflective structures in the dermis. The largest structure was measured to have a width of 0.13 mm. A good immediate correlation was found between histology and OCT imaging of the sample. Conclusion: The aetiology of the elongated structures is thought to be lymphomatous infiltrates. Similar findings have been described in ocular lymphoma and may therefore be an important characteristic of cutaneous lymphoma. It may further be speculated that the differences in OCT images may reflect the biological behaviour of the infiltrate. This observation therefore suggests that OCT imaging may be a relevant tool for the in vivo investigation of mycosis fungoides and other CTCLs, but in order to verify these observed patterns in OCT imaging, further investigations will be required. Copyright © 2012 S. Karger AG, Basel.

  13. Optical coherence tomography for evaluation of enamel and protective coatings.

    Science.gov (United States)

    Alsayed, Ehab Z; Hariri, Ilnaz; Sadr, Alireza; Nakashima, Syozi; Bakhsh, Turki A; Shimada, Yasushi; Sumi, Yasunori; Tagami, Junji

    2015-01-01

    Optical coherence tomography (OCT) is an interferometric imaging technique. This study aimed to employ OCT to evaluate four different resin-based materials including a coating containing glass-ionomer filler and calcium, a giomer, and two fluoride-releasing self-etch resins. The coating and its underlying and adjacent enamel were monitored using swept-source OCT (center wavelength: 1330 nm) at baseline, after 5,000 thermal cycles, and after 1, 4 and 7 days of demineralization (pH 4.5). The coatings showed different thicknesses (60-250 micrometers) and various levels of structural and interfacial integrity. OCT could detect a demineralization inhibition zone adjacent to the edge of the fluoride- and calcium-releasing material. Localized demineralization was occasionally observed under thinner coatings. Protection of susceptible enamel surfaces by thin resin-based bioactive coatings provides protection from demineralization. OCT can be used to non-destructively monitor the integrity of such coatings, as well as enamel changes beneath and adjacent to them. PMID:25748465

  14. Scatterer-size-based analysis of optical coherence tomography images

    Science.gov (United States)

    Pitris, Costas; Ioannides, Panayiotis; Kartakoulis, Andreas

    2007-02-01

    The early stages of malignancy, in most tissues, are characterized by unique cellular changes. Currently, these early changes are detectable only by confocal or multi-photon microscopy. Unfortunately, neither of the two imaging techniques can penetrate deep enough into the tissue to investigate the borders of thick lesions. A technique which would allow extraction of information regarding scatterer size from Optical Coherence Tomography (OCT) signals could prove a very powerful diagnostic tool and produce significant diagnostic insight. Such a procedure is proposed here. It is shown to be very effective in differentiating spectral differences which depend on scatterer size. The analysis of the OCT signal is based on spectral estimation techniques and statistical analysis. First, using autoregressive spectral estimation, it was deduced that tissues with different size scatterers exhibit marked differences in spectral content. Further, advanced analysis techniques, such as Principal Component Analysis (PCA) and Multivariate Analysis of Variance (MANOVA), provided more insight into the spectral changes. These techniques where tested on solutions of known scatterers and multilayered samples. The initial results are very encouraging and indicate that the spectral content of OCT signals can be used to extract scatterer size information. This technique can result in an extremely valuable tool for the investigation of disease tissue features which now remain below the resolution of OCT.

  15. Automated contact lens measurement using optical coherence tomography

    Science.gov (United States)

    Davidson, Bryan R.; Barton, Jennifer K.

    2009-02-01

    Optical Coherence Tomography (OCT) is a non-destructive imaging modality that has proven to be a useful tool for making quantitative measurements in a variety of applications. One area where non-destructive quantitative measurement is important is contact lens metrology, specifically prism. Prism is defined as the difference between the largest and smallest thickness measured at a fixed distance from the contact lens edge. We developed and tested an algorithm that automatically analyzes OCT images to accurately measure contact lens thickness. Images were obtained with the Thorlabs OCT930SR spectral radar OCT system. An automated rotation stage was used to precisely rotate the OCT probe 360 degrees in small increments to acquire OCT images along the entire outer edge of the contact lens. The algorithm was able to successfully analyze hundreds of OCT images. For comparison, measurements were taken by physically slicing contact lenses and manually measuring their thickness using a microscope. The error between the two measurements had a mean of -1.268 um and a range of 9.041 um. Thickness measurements were repeatable with a maximum range of 1.8 ?m. The success of the algorithm has demonstrated the possibility of using OCT images for performing non-destructive contact lens metrology.

  16. Corneal topography from spectral optical coherence tomography (sOCT).

    Science.gov (United States)

    Ortiz, Sergio; Siedlecki, Damian; Pérez-Merino, Pablo; Chia, Noelia; de Castro, Alberto; Szkulmowski, Maciej; Wojtkowski, Maciej; Marcos, Susana

    2011-12-01

    We present a method to obtain accurate corneal topography from a spectral optical coherence tomography (sOCT) system. The method includes calibration of the device, compensation of the fan (or field) distortion introduced by the scanning architecture, and image processing analysis for volumetric data extraction, segmentation and fitting. We present examples of three-dimensional (3-D) surface topography measurements on spherical and aspheric lenses, as well as on 10 human corneas in vivo. Results of sOCT surface topography (with and without fan-distortion correction) were compared with non-contact profilometry (taken as reference) on a spherical lens, and with non-contact profilometry and state-of-the art commercial corneal topography instruments on aspheric lenses and on subjects. Corneal elevation maps from all instruments were fitted by quadric surfaces (as well as by tenth-order Zernike polynomials) using custom routines. We found that the discrepancy in the estimated radius of curvature from nominal values in artificial corneas decreased from 4.6% (without fan distortion correction) to 1.6% (after fan distortion correction), and the difference in the asphericity decreased from 130% to 5%. In human corneas, the estimated corneal radius of curvature was not statistically significantly different across instruments. However, a Bland-Altman analysis showed consistent differences in the estimated asphericity and corneal shape between sOCT topographies without fan distortion correction and the rest of the measurements. PMID:22162814

  17. Determination of dental decay rates with optical coherence tomography

    International Nuclear Information System (INIS)

    We report the use of optical coherence tomography (OCT) to detect and quantify demineralization process induced by S. mutans biofilm in third molars human teeth. Artificial lesions were induced by a S. mutans microbiological culture and the samples (N = 50) were divided into groups according to the demineralization time: 3, 5, 7, 9, and 11 days. The OCT system was implemented using a light source delivering an average power of 96 ?W in the sample arm, and spectral characteristics allowing 23 ?m of axial resolution. The images were produced with lateral scans step of 10 ?m and analyzed individually. As a result of the evaluation of theses images, lesion depth was calculated as function of demineralization time. The depth of the lesion in the root dentine increased from 70 ?m to 230 ?m (corrected by the enamel refraction index, 1.62 @ 856 nm), depending of exposure time. The lesion depth in root dentine was correlated to demineralization time, showing that it follows a geometrical progression like a bacteria growth law

  18. Correlative cryo-electron tomography and optical microscopy of cells.

    Science.gov (United States)

    Zhang, Peijun

    2013-10-01

    The biological processes occurring in a cell are complex and dynamic, and to achieve a comprehensive understanding of the molecular mechanisms underlying these processes, both temporal and spatial information is required. While cryo-electron tomography (cryoET) provides three-dimensional (3D) still pictures of near-native state cells and organelles at molecular resolution, fluorescence light microscopy (fLM) offers movies of dynamic cellular processes in living cells. Combining and integrating these two commonly used imaging modalities (termed correlative microscopy) provides a powerful means to not only expand the imaging scale and resolution but also to complement the dynamic information available from optical microscopy with the molecular-level, 3D ultrastructure detail provided by cryoET. As such, a correlative approach performed on a given specimen can provide high resolution snapshots of dynamic cellular events. In this article, I review recent advances in correlative light microscopy and cryoET and discuss major findings made available by applying this method. PMID:23962486

  19. Characterization of PET preforms using spectral domain optical coherence tomography

    Science.gov (United States)

    Hosseiny, Hamid; Ferreira, Manuel João.; Martins, Teresa; Carmelo Rosa, Carla

    2013-11-01

    Polyethylene terephthalate (PET) preforms are massively produced nowadays with the purpose of producing food and beverages packaging and liquid containers. Some varieties of these preforms are produced as multilayer structures, where very thin inner film(s) act as a barrier for nutrients leakage. The knowledge of the thickness of this thin inner layer is important in the production line. The quality control of preforms production requires a fast approach and normally the thickness control is performed by destructive means out of the production line. A spectral domain optical coherence tomography (SD-OCT) method was proposed to examine the thin layers in real time. This paper describes a nondestructive approach and all required signal processing steps to characterize the thin inner layers and also to improve the imaging speed and the signal to noise ratio. The algorithm was developed by using graphics processing unit (GPU) with computer unified device architecture (CUDA). This GPU-accelerated white light interferometry technique nondestructively assesses the samples and has high imaging speed advantage, overcoming the bottlenecks in PET performs quality control.

  20. Assessment of transcutaneous vaccine delivery by optical coherence tomography

    International Nuclear Information System (INIS)

    Immunization is one of the most efficient and cost-effective means for the prevention of diseases. The latest trend for inducing protective immunity is topical application of vaccines to intact skin rather than invasive administration via injection. Apart from being a non-invasive route of drug delivery, skin itself also offers advantages through the presence of cells of the immune system in both the dermis and epidermis. However, vaccine penetration through the outermost layers of skin is limited by the barrier provided by the Stratum corneum. In the current study utilizing conventional Optical Coherence Tomography (OCT) we investigate the transcutaneous delivery of a nano- particulate peptide vaccine into mouse skin in vivo. We demonstrate that a front of molecular diffusion within the skin can be clearly observed by using cross-correlations of successive 2D OCT images. Thus, OCT provides a unique tool for quantitative assessment of dynamics of diffusion of drugs, target compounds, analytes, cosmetics and various chemical agents in biological tissues in vivo

  1. High performance time-resolved diffuse optical tomography system

    Science.gov (United States)

    Mo, Weirong; Chen, Nanguang

    2008-02-01

    In this paper, we present a high performance time-resolved diffuse optical tomography (DOT) system whose working principle and implementation are very different from the conventional methods and features near real-time data acquisition. Dual-wavelength near-infrared light at 784 nm and 808 nm are used as light source. A high bit rate pseudo-random bit sequence (2.488 GB/s) modulates both continuous lights when they go through the external intensity modulator. The diffuse photon density waves responding to such modulated light are detected by array of high sensitivity, high speed silicon avalanche photodetectors (APD). The temporal point spread function can be retrieved very quickly by using hardware auto-/cross-correlation. Our system implementation has achieved system impulse with rise time approaching 0.5 ns which is highly desirable for time-domain DOT application to penetrate depth in few centimeters. The temporal resolution is mainly limited by the photodetectors. System performance is stabilized with accurate temperature control over key components. Experiment results based on tissue-like phantoms verify our design is potential for breast cancer imaging.

  2. Magnetomotive optical coherence tomography for elastography of small biosamples

    Science.gov (United States)

    Oldenburg, Amy

    2008-10-01

    Optical coherence tomography (OCT) is a 3D micron-resolution imaging modality using the low-coherence properties of near-infrared light to render depth-resolved images typically a few millimeters into biological tissue. Visco-elasticity is an important parameter for detecting and staging various human diseases. We report a method for analyzing the visco-elastic properties of small tissue samples using magnetomotive OCT. Superparamagnetic nanoparticles (MNPs, ˜20nm) are diffused into a tissue sample. Subsequently, an electromagnet is modulated with a chirped frequency waveform from 0-1kHz, providing a modulated force on the MNPs in the tissue. The mechanical response of the tissue is recorded using OCT at linerates of 1-10kHz. Because OCT is a coherence imaging technique, sub-wavelength displacements are detected in the phase of the interferogram. The mechanical frequency response and associated phase lag fit a model for a damped harmonic oscillator, and results in homogeneous agarose cylinders can be interpreted in terms of Love's solutions for longitudinal vibration modes. A rat mammary tumor biopsy was also analyzed with this technique during formaldehyde fixation, and a trend toward higher frequency correlates with stiffening of the tissue during the fixation process. In collaboration with Stephen Boppart, University of Illinois at Urbana-Champaign.

  3. Fundus based eye tracker for optical coherence tomography.

    Science.gov (United States)

    Ip, Louisa Pui Sum; Nguyen, Truong Q; Bartsch, Dirk-Uwe

    2004-01-01

    Current optical coherence tomography (OCT) relies on patient cooperation to maintain fixation. For patients with eye complications, it is extremely difficult to achieve fixation on the eye. Most eye trackers are external and track only the pupils. Such method is not useful for the OCT. The only existing fundus image based tracker is a hardware-based system that is composed of a confocal reflectometer, dither scanner, and tracking galvanometers. The integration of such hardware based system with the OCT is not as desirable nor as portable. Therefore, we want an eye tracking system that can be installed in the computer connected to the OCT. In this paper, a real time internal eye tracking software based system is proposed. By combining intensity based object tracking adaptive mean shift algorithm with Kalman filtering techniques together, a robust real time eye tracking algorithm is proposed. The system is robust in terms of its acceptance to low resolution, coarsely quantized, or extremely noisy images and still able to produce desirable results with no pre-processing of images. PMID:17271982

  4. Three Dimensional Optical Coherence Tomography Imaging: Advantages and Advances

    Science.gov (United States)

    Gabriele, Michelle L; Wollstein, Gadi; Ishikawa, Hiroshi; Xu, Juan; Kim, Jongsick; Kagemann, Larry; Folio, Lindsey S; Schuman, Joel S.

    2010-01-01

    Three dimensional (3D) ophthalmic imaging using optical coherence tomography (OCT) has revolutionized assessment of the eye, the retina in particular. Recent technological improvements have made the acquisition of 3D-OCT datasets feasible. However, while volumetric data can improve disease diagnosis and follow-up, novel image analysis techniques are now necessary in order to process the dense 3D-OCT dataset. Fundamental software improvements include methods for correcting subject eye motion, segmenting structures or volumes of interest, extracting relevant data post hoc and signal averaging to improve delineation of retinal layers. In addition, innovative methods for image display, such as C-mode sectioning, provide a unique viewing perspective and may improve interpretation of OCT images of pathologic structures. While all of these methods are being developed, most remain in an immature state. This review describes the current status of 3D-OCT scanning and interpretation, and discusses the need for standardization of clinical protocols as well as the potential benefits of 3D-OCT scanning that could come when software methods for fully exploiting these rich data sets are available clinically. The implications of new image analysis approaches include improved reproducibility of measurements garnered from 3D-OCT, which may then help improve disease discrimination and progression detection. In addition, 3D-OCT offers the potential for preoperative surgical planning and intraoperative surgical guidance. PMID:20542136

  5. Fast retinal layer identification for optical coherence tomography images

    Science.gov (United States)

    Fabritius, Tapio; Makita, Shuichi; Miura, Masahiro; Yasuno, Yoshiaki; Myllylä, Risto

    2011-03-01

    Fast method for identifying the internal limiting membrane (ILM) and retinal pigment epithelium (RPE) from optical coherence tomography images is demonstrated. To avoid unnecessary increment of calculation time, a strong downsampling of the original data set is performed to reduce a number of processed pixels. In ILM segmentation, the obtained data cube is filtered with two different kinds of parameters and two estimates for the position of ILM is determined. A simple smoothness value is determined for both estimates and better estimate is used for future processing. A smaller portion of pixels around estimated ILM are extracted from the down sampled data and filtered again and new estimation for ILM position is determined. That procedure is repeated with smaller portion of pixels around ILM and with different filtering parameters. The principle of RPE segmentation is very much similar with ILM identification. Only the used filtering and processing parameters are changed. Algorithm was tested with eight data sets with good reliability. Over 97% of each scans had smaller segmentation error than 5 pixels. Total required data processing time (ILM and RPE segmentation) for data volume with (600x1500x128) pixels was less than 9 seconds.

  6. Optical coherence tomography for the diagnosis of human otitis media

    Science.gov (United States)

    Cho, Nam Hyun; Jung, Unsang; Jang, Jeong Hun; Jung, Woonggyu; Kim, Jeehyun; Lee, Sang Heun; Boppart, Stephen A.

    2013-05-01

    We report the application of Optical Coherence Tomography (OCT) to various types of human cases of otitis media (OM). Whereas conventional diagnostic modalities for OM, including standard and pneumatic otoscopy, are limited to visualizing the surface information of the tympanic membrane (TM), OCT is able to effectively reveal the depth-resolved microstructural below the TM with a very high spatial resolution. With the potential advantage of using OCT for diagnosing different types of OM, we examined in-vivo the use of 840 nm wavelength, and OCT spectral domain OCT (SDOCT) techniques, in several human cases including normal ears, and ears with adhesive and effusion types of OM. Peculiar positions were identified in two-dimensional OCT images of abnormal TMs compared to images of a normal TM. Analysis of A-scan (axial depth-scans) data from these positions could successfully identify unique patterns for different constituents within effusions. These OCT images may not only be used for constructing a database for the diagnosis and classification of OM, but they may also demonstrate the feasibility and advantages for upgrading the current otoscopy techniques.

  7. Skin optical clearing enhancement with penetration enhancer azone using spectroscopy and optical coherence tomography

    Science.gov (United States)

    Xu, Xiangqun; Zhu, Qiuhong

    2008-06-01

    In order to find a non-invasive way to improve the efficacy of skin optical clearing with topically applied optical clearing agents (OCA), we evaluated the effect of azone ® (epsilon-Laurocapram) as a chemical penetration enhancer on optical clearing of intact skin in vitro. Fresh porcine skin with topical application of glycerol (G) mixed with water-soluble azone (A) was investigated using near-infrared spectroscopy and optical coherence tomography (OCT). Light transmittance at 1276 nm increased by 41% and diffuse reflectance at 1066 nm decreased by 29% at 60 min after treatment with 40%G5%A on a spectrophotometer with an internal integrating sphere. 40% glycerol with addition of azone was a more effective optical clearing agent than 40% and 80% glycerol. 60%G/5%A led to a 2-fold increase in achievable OCT imaging depth and a 2.2-fold increase in light intensity reflected off the underneath needle surface after 60 minutes in the OCT in-depth reflectance profiles. In conclusion, skin optical clearing with the topical application of glycerol was markedly enhanced by water-soluble azone. Skin permeation enhancing effect of azone accounts probably for the skin clearing enhancement.

  8. High-resolution full-field spatial coherence gated optical tomography using monochromatic light source

    Science.gov (United States)

    Srivastava, Vishal; Nandy, Sreyankar; Singh Mehta, Dalip

    2013-09-01

    We demonstrate dispersion free, high-resolution full-field spatial coherence gated optical tomography using spatially incoherent monochromatic light source. Spatial coherence properties of light source were synthesized by means of combining a static diffuser and vibrating multi mode fiber bundle. Due to low spatial coherence of light source, the axial resolution of the system was achieved similar to that of conventional optical coherence tomography which utilizes low temporal coherence. Experimental results of fringe visibility versus optical path difference are presented for varying numerical apertures objective lenses. High resolution optically sectioned images of multilayer onion skin, and red blood cells are presented.

  9. «Optical Coherence Tomography» en desgarro del epitelio pigmentario retiniano «Optical Coherence Tomography» of retinal pigment epithelial tears

    Directory of Open Access Journals (Sweden)

    C. Torrón-Fernández-Blanco

    2007-04-01

    Full Text Available Casos clínicos: Se presentan 3 pacientes con desgarro de epitelio pigmentario retiniano (EPR. En dos de ellos, éste se produjo de manera espontánea, estando el tercero en relación con la fotocoagulación de una neovascularización extrafoveal. Se realizaron angiografías (AGF y estudio con tomografia óptica de coherencia (OCT que confirmaron el diagnóstico. Discusión: Existen pocos estudios sobre OCT en desgarro del EPR. Las principales características son: interrupción de la línea hiperreflectante del EPR, hiperreflectividad de la coroides en la zona de ausencia de EPR y doble capa de EPR donde éste está replegado. Es frecuente el desprendimiento de EPR y neurosensorial asociado.Case reports: Three cases of pigmentary epithelial tears are described in this study. One of them was related to previous extrafoveal photocoagulation, whereas the other two were idiopathic. Fluorescein angiography (FA and optical coherence tomography (OCT were performed to confirm the clinical diagnosis. Discussion: Few studies using OCT to assess pigmentary retinal epithelial (RPE tears have been published in the world literature. The main findings of our study included hyper-reflectant line breaks, choroidal hyper-reflectance due to the lack of RPE and RPE double layering where it was folded. Images were frequently associated with RPE tears and neurosensorial retinal detachment.

  10. «Optical Coherence Tomography» en desgarro del epitelio pigmentario retiniano / «Optical Coherence Tomography» of retinal pigment epithelial tears

    Scientific Electronic Library Online (English)

    C., Torrón-Fernández-Blanco; E., Ferrer-Novella; O., Ruiz-Moreno; F.M., Honrubia-López.

    2007-04-01

    Full Text Available SciELO Spain | Language: Spanish Abstract in spanish Casos clínicos: Se presentan 3 pacientes con desgarro de epitelio pigmentario retiniano (EPR). En dos de ellos, éste se produjo de manera espontánea, estando el tercero en relación con la fotocoagulación de una neovascularización extrafoveal. Se realizaron angiografías (AGF) y estudio con tomografia [...] óptica de coherencia (OCT) que confirmaron el diagnóstico. Discusión: Existen pocos estudios sobre OCT en desgarro del EPR. Las principales características son: interrupción de la línea hiperreflectante del EPR, hiperreflectividad de la coroides en la zona de ausencia de EPR y doble capa de EPR donde éste está replegado. Es frecuente el desprendimiento de EPR y neurosensorial asociado. Abstract in english Case reports: Three cases of pigmentary epithelial tears are described in this study. One of them was related to previous extrafoveal photocoagulation, whereas the other two were idiopathic. Fluorescein angiography (FA) and optical coherence tomography (OCT) were performed to confirm the clinical di [...] agnosis. Discussion: Few studies using OCT to assess pigmentary retinal epithelial (RPE) tears have been published in the world literature. The main findings of our study included hyper-reflectant line breaks, choroidal hyper-reflectance due to the lack of RPE and RPE double layering where it was folded. Images were frequently associated with RPE tears and neurosensorial retinal detachment.

  11. Nondestructive metrology by optical coherence tomography empowering manufacturing iterations of layered polymeric optical materials

    Science.gov (United States)

    Yao, Jianing; Meemon, Panomsak; Lee, Kye-Sung; Rolland, Jannick P.

    2013-11-01

    In recent years, there has been an ever-growing interest in exploring different optical materials and components to develop compact and effective optical systems. The design and fabrication of high-performance optics require nondestructive metrology techniques to inspect the samples. We have investigated the capability of optical coherence tomography (OCT) to nondestructively characterize layered polymeric materials. Using a custom developed Gabor-domain optical coherence microscopy system centered at 800 nm with 120 nm full width at half maximum enabling unprecedented 2 ?m resolution both laterally and axially in an 8 mm3 volume, we investigated the internal structure of 50 ?m thick films and layered sheets, which prompted the manufacturing process to adopt a compatibilization technique. Based on a custom swept-source OCT system centered at 1320 nm with expanded imaging field-of-view and latest depth of imaging extended to ˜5 mm, we performed nondestructive metrology of the layer thickness profiles over the depth of a monolithic layered sheet and diagnosed a film compression issue within the sheet. With the OCT metrology, the manufacturing process has been advanced and the layer thickness profile of a recent layered gradient refractive index sheet shows improved uniformity through depth.

  12. Voice coil based robust and miniature optical delay for multiple reference optical coherence tomography

    Science.gov (United States)

    Dsouza, Roshan; Subhash, Hrebesh; Neuhaus, Kai; Hogan, Josh; Wilson, Carol; Leahy, Martin

    2014-02-01

    Multiple reference optical coherence tomography (MR-OCT) is a recently developed time-domain interferometeric imaging platform, which promises to fit into robust, cost-effective designs that are virtually solid state. An optical delay is created by the reference mirror which is mounted on a piezo-electric transducer (PZT) and the key element of MR-OCT technology is the presence of a partial mirror in front of the reference mirror. However, the limited axial displacement range at higher scanning-frequencies are a limitation of a PZT-based optical delay. Moreover, PZT-based actuators require a relatively high operational voltage and are expensive. In this paper we present a voice coil actuator as an alternative to a PZT-based optical delay. Voice coil actuators are light in weight, inexpensive and offer other advantages such as zero hysteresis, low operational voltage and a long life. We demonstrate a voice coil actuator as a feasible alternative to PZT-based actuators for the purpose of creating an optical delay, which can provide fast and precise axial displacements at high scanning rates.

  13. Optical Sensing Method for Screening Disease in Melon Seeds by Using Optical Coherence Tomography

    Directory of Open Access Journals (Sweden)

    Jeehyun Kim

    2011-10-01

    Full Text Available We report a noble optical sensing method to diagnose seed abnormalities using optical coherence tomography (OCT. Melon seeds infected with Cucumber green mottle mosaic virus (CGMMV were scanned by OCT. The cross-sectional sensed area of the abnormal seeds showed an additional subsurface layer under the surface which is not found in normal seeds. The presence of CGMMV in the sample was examined by a blind test (n = 140 and compared by the reverse transcription-polymerase chain reaction. The abnormal layers (n = 40 were quantitatively investigated using A-scan sensing analysis and statistical method. By utilizing 3D OCT image reconstruction, we confirmed the distinctive layers on the whole seeds. These results show that OCT with the proposed data processing method can systemically pick up morphological modification induced by viral infection in seeds, and, furthermore, OCT can play an important role in automatic screening of viral infections in seeds.

  14. Optical sensing method for screening disease in melon seeds by using optical coherence tomography.

    Science.gov (United States)

    Lee, Changho; Lee, Seung-Yeol; Kim, Jeong-Yeon; Jung, Hee-Young; Kim, Jeehyun

    2011-01-01

    We report a noble optical sensing method to diagnose seed abnormalities using optical coherence tomography (OCT). Melon seeds infected with Cucumber green mottle mosaic virus (CGMMV) were scanned by OCT. The cross-sectional sensed area of the abnormal seeds showed an additional subsurface layer under the surface which is not found in normal seeds. The presence of CGMMV in the sample was examined by a blind test (n = 140) and compared by the reverse transcription-polymerase chain reaction. The abnormal layers (n = 40) were quantitatively investigated using A-scan sensing analysis and statistical method. By utilizing 3D OCT image reconstruction, we confirmed the distinctive layers on the whole seeds. These results show that OCT with the proposed data processing method can systemically pick up morphological modification induced by viral infection in seeds, and, furthermore, OCT can play an important role in automatic screening of viral infections in seeds. PMID:22163706

  15. Scattering optical coherence angiography with 1-?m swept source optical coherence tomography

    Science.gov (United States)

    Yasuno, Yoshiaki; Hong, Youngjoo; Makita, Shuichi; Akiba, Masahiro; Miura, Masahiro; Yatagai, Toyohiko

    2007-07-01

    Retinal and choroidal imaging by using swept-source optical coherence tomography (SS-OCT) with a 1-?m band probe light, and high-contrast and three-dimensional (3D) imaging of choroidal vasculature are presented. This SS-OCT has a measurement speed of 28,000 A-lines/s, a depth resolution of 10.4 ?m in tissue, and a sensitivity of 99.3 dB. A software-based algorithm for scattering optical coherence angiography (S-OCA) is developed for the high-contrast and 3D imaging of the choroidal vessels. This OCT is employed for the investigation of age related macular degeneration and visualizes structures beneath the retinal pigment epithelial detachment.

  16. Theoretical study of Acousto-optical coherence tomography using random phase jumps on US and light

    OpenAIRE

    Lesaffre, Max; Farahi, Salma; Boccara, A. C.; Ramaz, Franc?ois; Gross, Michel

    2011-01-01

    Acousto-Optical Coherence Tomography (AOCT) is variant of Acousto Optic Imaging (called also ultrasonic modulation imaging) that makes possible to get z resolution with acoustic and optic Continuous Wave (CW) beams. We describe here theoretically the AOCT e ect, and we show that the Acousto Optic tagged photons remains coherent if they are generated within a speci c z region of the sample. We quantify the z selectivity for both the tagged photon eld, and for the M. Lesa re e...

  17. Common path optical coherence tomography based on fiber bundle imager

    Science.gov (United States)

    Han, Jae Ho

    Optical coherence tomography (OCT) has emerged as a promising medical imaging modality that can provide non-invasive high-resolution tomographic imaging in real-time. Generating high-resolution OCT images in real-time requires a complicated and costly system design. Therefore, there has been an interest in the development of a common-path (CP) approach to OCT which utilizes a simple interferometer where the sample and reference arms share a common optical path. This configuration allows a much simpler system design, lower associated costs, and the ability to use interchangeable probes as well as the freedom to use any arbitrary probe arm length. In this thesis, novel CP optic probes and image processing methods that could make the CP-OCT a practical system for a high-resolution endoscopic imaging have been developed and investigated. Despite the advantages of CP based OCT configurations, CP-OCT have had limited applications since the reference signal is usually obtained from the Fresnel reflection from the distal end of the optical fiber probe. Thus, when the probe is submerged in an aqueous medium or in contact with a target, the magnitude of the reflected power decreases due to the reduced index difference at the fiber probe reference plane. To solve this problem, gold-plated fiber probes were investigated for in situ imaging of retina and surrounding tissues. The probe operating in an aqueous medium was able to provide OCT images that can differentiate various retinal layers. To obtain 2D images, OCT requires a series of axial scans performed by mechanical spatial translation of the probe or the beam. Most current OCT systems use various miniaturized scanning probes in order to obtain lateral scanning. Alternatively, fiber bundle imagers have recently been suggested. However, the results so far have not been promising due to the inefficient coupling of light into the cores and the non-uniformity of the fiber array. Since CP-OCT obtains the reference at the distal end of the probe, it can overcome the difference between the optical properties between the fiber bundle pixels. In this work, the feasibility of pseudo-scanningless probe has been explored based on fiber bundle imager in the CP-OCT. The mechanical lateral scans are accomplished outside the specimen at the proximal entrance of the fiber bundle. This eliminated the need for moving parts in the distal end of the probe. Finally, to enhance the quality of OCT images obtained using a fiber bundle imager. An image processing method that can remove the fiber bundle's pixelation artifact due to the inherent arrangement of the fiber core arrays is proposed and studied. This method of eliminating pixelization effect from en face OCT image is based on applying a histogram equalization process followed by a weighted-averaged Gaussian smoothing filtering to not only remove the structural artifact of the bundle but also to enhances the image quality with minimum blurring of object's image features.

  18. Development and Application of Multifunctional Optical Coherence Tomography

    Science.gov (United States)

    Zhi, Zhongwei

    Microcirculation refers to the functions of capillaries and the neighboring lymphatic vessels. It plays a vital role in the pathophysiology of disorders in many clinical areas including cardiology, dermatology, neurology and ophthalmology, and so forth. It is crucial to develop imaging technologies that can provide both qualitative and quantitative information as to how microcirculation responds to certain injury and/or disease, and its treatment. Optical coherence tomography (OCT) is a non-invasive optical imaging technique for high-resolution cross-sectional imaging of specimens, with many applications in clinical medicine. Current state-of-the-art OCT systems operate in the Fourier domain, using either a broadband light source with a spectrometer, known as spectral domain OCT (SDOCT), or a rapidly tunable laser, known as swept source OCT (SSOCT). The current Fourier domain OCT systems have dramatically improvement in sensitivity, resolution and speed compared to time domain OCT. In addition to the improvement in the OCT system hardware, different methods for functional measurements of tissue beds have been developed and demonstrated. This includes but not limited to, i) Phase-resolved Doppler OCT for quantifying the blood flow, ii) OCT angiography for visualization of microvasculature, iii) Polarization sensitive OCT for measuring the intrinsic optical property/ birefringence of tissue, iv) spectroscopic OCT for measuring blood oxygenation, etc. Functional OCT can provide important clinical information that is not available in the typical intensity based structural OCT images. Among these functional OCT modalities, Doppler OCT and OCT angiography attract great interests as they show high capability for in vivo study of microvascular pathology. By analyzing the Doppler effect of a flowing particle on light frequency, Doppler OCT allows the quantification of the blood flow speed and blood flow rate. The most popular approach for Doppler OCT is achieved through analysis of the phase term in complex OCT signal which termed as Phase-resolved Doppler OCT. However, as limited by the phase noise and motion, Phase-resolved Doppler OCT can only be applied for relative large blood vessels, such as arterioles and venules. On the other hand, in order to visualize the microcirculation network, a number of strategies to enable better contrast of microvasculature components, which we termed OCT angiography, have been introduced during recent years. As a variation of Fourier domain OCT, optical microangiography (OMAG) is one of earliest proposed OCT angiography technique which is capable of generating 3D images of dynamic blood perfusion distribution within microcirculatory tissue beds. The OMAG algorithm works by separating the static and moving elements by high pass filtering on complex valued interferometric data after Fourier transform. Based on the conventional OMAG algorithm, we further developed ultra-high sensitive OMAG (UHS-OMAG) by switching the high-pass filtering from fast scan direction (adjacent A-lines within one B-frame) to slow scan direction (adjacent B-frames), which has a dramatically improved performance for capillary network imaging and analysis. Apart from the microvascular study with current available functional OCT for, visualization of the lymphatic system (lymph nodes and lymphatic vessels) plays a significant role in assessing patients with various malignancies and lymphedema. However, there is a lack of label-free and noninvasive method for lymphangiography. Hence, a cutting edge research to investigate the capability of OCT as a tool for non-invasive and label-free lymphangiography would be highly desired. The objective of my thesis is to develop a multiple-functional SDOCT system to image the microcirculation and quantify the several important parameters of microcirculation within microcirculatory tissue beds, and further apply it for pre-clinical research applications. The multifunctional OCT system provides modalities including structural OCT, OCT angiography, Doppler OCT and Optical lymphangiography,

  19. 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)

    Tearney, Guillermo J; Regar, Evelyn

    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 the diagnosis and treatment of patients with atherosclerosis, including coronary artery disease.

  20. Fluorescein angiography and optical coherence tomography in myopic choroidal neovascularization.

    Science.gov (United States)

    Chhablani, J; Deepa, M J; Tyagi, M; Narayanan, R; Kozak, I

    2015-04-01

    PurposeTo assess intra/inter-observer agreement, and diagnostic capabilities of a color fundus photograph, fundus fluorescein angiography (FFA), and spectral domain optical coherence tomography (SD-OCT) in making a diagnosis of myopic choroidal neovascularization (CNV).Patients and methodsTwo masked observers evaluated FFA and SD-OCT images to identify the presence of myopic CNV in 80 high-myopic eyes of 57 patients. A third masked observer identified CNV on a color fundus photo. Presence of myopic CNV on a fundus photo was defined as presence of subretinal hemorrhage, thickening of the retina and/or visible membrane at the macula. Presence of myopic CNV on FFA was defined as hyperfluorescence in the early phase with increase in intensity and size in the late phase; presence of a large irregular lesion; and hypofluorsescence due to subretinal hemorrhage. Myopic CNV on SD-OCT was defined as the hyper-reflective lesion with or without intraretinal fluid or subretinal fluid with retinal thickening.ResultsIntraobserver repeatability on FFA and SD-OCT was 0.54 and 0.44, respectively. Agreement (kappa) between FFA and SD-OCT was 0.38 and 0.3, respectively. Among 34 eyes, which had the presence of CNV on a color fundus photo, CNV was diagnosed in 18 (53%) eyes on FFA and in 20 (58.8%) eyes on SD-OCT. Sensitivity and specificity of FFA was 47 and 80.4%, respectively, and that of SD-OCT was 58.8 and 86.9%, respectively.ConclusionRepeatability and reproducibility for diagnosis of myopic CNV was better with FFA compared with SD-OCT; however, agreement is very poor between FFA and SD-OCT. SD-OCT is comparatively a better tool to rule out presence of myopic CNV. PMID:25613842

  1. Optical coherence tomography of the rat cavernous nerves

    Science.gov (United States)

    Fried, Nathaniel M.; Rais-Bahrami, Soroush; Lagoda, Gwen A.; Chuang, Ying; Burnett, Arthur L.; Su, Li-Ming

    2007-02-01

    Improvements in identification, imaging, and visualization of the cavernous nerves during radical prostatectomy, which are responsible for erectile function, may improve nerve preservation and postoperative potency. Optical coherence tomography (OCT) is capable of real-time, high-resolution, cross-sectional, in vivo tissue imaging. The rat prostate serves as an excellent model for studying the use of OCT for imaging the cavernous nerves, as the rat cavernous nerve is a large, visible, and distinct bundle allowing for easy identification with OCT in addition to histologic confirmation. Imaging was performed with the Niris OCT system and a handheld 8 Fr probe, capable of acquiring real-time images with 11-?m axial and 25-?m lateral resolution in tissue. Open surgical exposure of the prostate was performed on a total of 6 male rats, and OCT images of the prostate, cavernous nerve, pelvic plexus ganglion, seminal vesicle, blood vessels, and periprostatic fat were acquired. Cavernous nerve electrical stimulation with simultaneous intracorporeal pressure measurements was performed to confirm proper identification of the cavernous nerves. The prostate and cavernous nerves were also processed for histologic analysis and further confirmation. Cross-sectional and longitudinal OCT images of the cavernous nerves were acquired and compared with histologic sections. The cavernous nerve and ganglion could be differentiated from the surrounding prostate gland, seminal vesicle, blood vessels, bladder, and fatty tissue. We report preliminary results of OCT images of the rat cavernous nerves with histologic correlation and erectile stimulation measurements, thus providing interpretation of prostate structures as they appear in OCT images.

  2. Optical coherence tomography using the Niris system in otolaryngology

    Science.gov (United States)

    Rubinstein, Marc; Armstrong, William B.; Djalilian, Hamid R.; Crumley, Roger L.; Kim, Jason H.; Nguyen, Quoc A.; Foulad, Allen I.; Ghasri, Pedram E.; Wong, Brian J. F.

    2009-02-01

    Objectives: To determine the feasibility and accuracy of the Niris Optical Coherence Tomography (OCT) system in imaging of the mucosal abnormalities of the head and neck. The Niris system is the first commercially available OCT device for applications outside ophthalmology. Methods: We obtained OCT images of benign, premalignant and malignant lesions throughout the head and neck, using the Niris OCT imaging system (Imalux, Cleveland, OH). This imaging system has a tissue penetration depth of approximately 1-2mm, a scanning range of 2mm and a spatial depth resolution of approximately 10-20?m. Imaging was performed in the outpatient setting and in the operating room using a flexible probe. Results: High-resolution cross-sectional images from the oral cavity, nasal cavity, ears and larynx showed distinct layers and structures such as mucosa layer, basal membrane and lamina propria, were clearly identified. In the pathology images disruption of the basal membrane was clearly shown. Device set-up took approximately 5 minutes and the image acquisition was rapid. The system can be operated by the person performing the exam. Conclusions: The Niris system is non invasive and easy to incorporate into the operating room and the clinic. It requires minimal set-up and requires only one person to operate. The unique ability of the OCT offers high-resolution images showing the microanatomy of different sites. OCT imaging with the Niris device potentially offers an efficient, quick and reliable imaging modality in guiding surgical biopsies, intra-operative decision making, and therapeutic options for different otolaryngologic pathologies and premalignant disease.

  3. Evaluation of caries-affected dentin with optical coherence tomography

    Directory of Open Access Journals (Sweden)

    Cynthia Soares de Azevedo

    2011-10-01

    Full Text Available The purpose of this study was to evaluate the degree of demineralization of artificially induced caries-affected human dentin by an in vitro microbiological method. The occlusal surfaces of 6 human molar teeth were abraded until a flat surface was obtained, and the enamel was removed to expose the occlusal dentin surface. These teeth were sectioned in 12 halves in the vestibular-lingual direction and divided into 3 groups according to the period length of the microbiological essay (n = 4: G1, 7 days; G2, 14 days; and G3, 21 days. The surfaces of all specimens were protected by an acid-resistant nail varnish, except for a window where the caries lesion was induced by a Streptoccocus mutans biofilm in a batch-culture model supplemented with 5% sucrose. The specimens were then analyzed by optical coherence tomography (OCT with a super-luminescent light diode (? = 930 nm with 6.0-µm lateral and longitudinal resolution (in the air. Qualitative and quantitative results (images and average dentin demineralization, respectively were obtained. The mean demineralization depths were (µm 235 ± 31.4, 279 ± 14, and 271 ± 8.3 in groups 1, 2, and 3, respectively. In addition, no significant change was observed in the lesion mean depth from 7 days of cariogenic challenge on. In conclusion, OCT was shown to be an efficient and non-invasive method to detect the depths of lesions caused by demineralization. Further, a seven-day demineralization time was considered sufficient for caries-affected dentin to be obtained.

  4. Evaluation of caries-affected dentin with optical coherence tomography

    Scientific Electronic Library Online (English)

    Cynthia Soares de, Azevedo; Luciana Cardoso Espejo, Trung; Maria Regina Lorenzetti, Simionato; Anderson Zanardi de, Freitas; Adriana Bona, Matos.

    2011-10-01

    Full Text Available SciELO Brazil | Language: English Abstract in english The purpose of this study was to evaluate the degree of demineralization of artificially induced caries-affected human dentin by an in vitro microbiological method. The occlusal surfaces of 6 human molar teeth were abraded until a flat surface was obtained, and the enamel was removed to expose the o [...] cclusal dentin surface. These teeth were sectioned in 12 halves in the vestibular-lingual direction and divided into 3 groups according to the period length of the microbiological essay (n = 4): G1, 7 days; G2, 14 days; and G3, 21 days. The surfaces of all specimens were protected by an acid-resistant nail varnish, except for a window where the caries lesion was induced by a Streptoccocus mutans biofilm in a batch-culture model supplemented with 5% sucrose. The specimens were then analyzed by optical coherence tomography (OCT) with a super-luminescent light diode (? = 930 nm) with 6.0-µm lateral and longitudinal resolution (in the air). Qualitative and quantitative results (images and average dentin demineralization, respectively) were obtained. The mean demineralization depths were (µm) 235 ± 31.4, 279 ± 14, and 271 ± 8.3 in groups 1, 2, and 3, respectively. In addition, no significant change was observed in the lesion mean depth from 7 days of cariogenic challenge on. In conclusion, OCT was shown to be an efficient and non-invasive method to detect the depths of lesions caused by demineralization. Further, a seven-day demineralization time was considered sufficient for caries-affected dentin to be obtained.

  5. Multiple step algorithms for fluorescence -enhanced diffuse optical tomography

    International Nuclear Information System (INIS)

    A discussion on recent works on diffusive inverse problems is presented with a special focus n three-dimensional shape-based imaging methods and their application to small animal imaging by fluorescence-enhanced Diffuse Optical Tomography (DOT). Numerical approaches (Finite Element Method) for handling problems modelled by elliptic coupled PDEs is justified by the complexity of the geometry of the system but is known to be time-and memory-consuming. The use of an 'adjoint field technique' considerably speeds up the treatment and allows a full 3D resolution. Nevertheless, because of the ill-posing of the problem, the reconstruction scheme is sensitive to a priori knowledge on the parameters to be reconstructed. Multiple modality imaging techniques (DOT coupled with CT or MRI for example) is becoming of great interest for introducing a priori knowledge of the regions of interest (ROI) and justifies the use of shape-based methods that reduces the dimension of the system, by identifying a finite number of ROI (absorption, scattering and/or, in our case, fluorescent zones), and intrinsically regularizes the reconstruction of the desired parameters. This study led to the proposal of a multiple step, self regularized, reconstruction algorithm of the bio-distribution of molecular fluorescent probes specially designed for tumour targeting. We introduce the a priori knowledge of the ROI via a segmentation of the results performed with a first rough reconstruction of the fluorescent regions. The results are then refined along iterations of the segmentation/reconstruction scheme. Measurements were performed on calibrated objects (phantoms) as well as in vivo (nude mice) with a plane parallel plate tomographer using a CCD camera as a detection scheme. (authors)

  6. Assessment of coronary atherosclerosis using optical coherence tomography.

    Science.gov (United States)

    Kubo, Takashi; Tanaka, Atsushi; Ino, Yasushi; Kitabata, Hironori; Shiono, Yasutsugu; Akasaka, Takashi

    2014-01-01

    Optical coherence tomography (OCT) is a catheter-based imaging system that uses near-infrared light to produce cross-sectional images of the coronary arteries. With its extraordinarily high resolution (10-20 ?m), OCT allows clinicians to observe various morphological features of coronary atherosclerosis in vivo. For example, intimal thickening presents as homogeneous, signal-rich regions on OCT, while fibroatheroma with a lipid-rich necrotic core is characterized by the presence of signal-poor regions with a diffuse border. Furthermore, plaque rupture is detected in 50?70% of culprit lesions of acute coronary syndrome (ACS), and plaque erosion develops over areas of intimal thickening and/or thick-cap fibroatheroma. Meanwhile, calcified nodules are common in older patients with hypertension and chronic renal disease. Platelet-rich thrombi are visualized as low backscattering structures and often detected in patients with unstable angina, whereas red blood cell-rich thrombi exhibit a high backscattering structure with signal-free shadowing and are frequently noted in patients with acute myocardial infarction. Moreover, OCT-derived thin cap fibroatheroma has been shown to be a predictor of subsequent plaque progression and acute coronary events, while vasa vasorum and the macrophage density are associated with a thin fibrous cap and large necrotic core as well as increased serum levels of inflammatory biomarkers. One current challenge of OCT examinations is to detect morphologic characteristics capable of discriminating vulnerable from stable plaques. The ability to detect vulnerable plaques in vivo would allow physicians to identify patients at high risk for adverse coronary events, thus significantly helping to prevent ACS. PMID:25069815

  7. Quantitative analysis of low contrast detectability in optical coherence tomography

    Science.gov (United States)

    Woolsey, Nicholas; Wang, Hsing-Wen; Agrawal, Anant; Wang, Jianting; Liang, Chia-Pin; Chen, Yu; Pfefer, Joshua

    2014-05-01

    Optical coherence tomography (OCT) is a high resolution imaging technology that is rapidly being adopted as the standard of care for medical applications such as ocular and intravascular imaging. However, clinical translation has been hampered by the lack of standardized test methods for performance evaluation as well as consensus standards analogous to those that have been developed for established medical imaging modalities (e.g., ultrasound). In this study, we address low contrast detectability, specifically, the ability of systems to differentiate between regions exhibiting small differences in scattering coefficient. Based on standard test methods for established medical imaging modalities, we have developed layered phantoms with well-characterized scattering properties in a biologically relevant range. The phantoms consisted of polydimethylsiloxane (PDMS) doped with varying concentrations of BaSO4 microparticles. Microfabrication processes were used to create layered and channel schemes. Two spectral domain OCT systems - a Fourier domain system at 855 nm and a swept-source device at 1310 nm - were then used to image the phantoms. The detectability of regions with different scattering levels was evaluated for each system by measuring pixel intensity differences. Confounding factors such as the inherent attenuation of the phantoms, signal intensity decay due to focusing and system roll-off were also encountered and addressed. Significant differences between systems were noted. The minimum differences in scattering coefficient that the Fourier domain and swept source systems could differentiate was 1.50 and 0.46 mm-1 respectively. Overall, this approach to evaluating low contrast detectability represents a key step towards the development of standard test methods to facilitate clinical translation of novel OCT systems.

  8. Improvement of fluorescence-enhanced optical tomography with improved optical filtering and accurate model-based reconstruction algorithms

    OpenAIRE

    Lu, Yujie; Zhu, Banghe; Darne, Chinmay; Tan, I-chih; Rasmussen, John C.; Sevick-muraca, Eva M.

    2011-01-01

    The goal of preclinical fluorescence-enhanced optical tomography (FEOT) is to provide three-dimensional fluorophore distribution for a myriad of drug and disease discovery studies in small animals. Effective measurements, as well as fast and robust image reconstruction, are necessary for extensive applications. Compared to bioluminescence tomography (BLT), FEOT may result in improved image quality through higher detected photon count rates. However, background signals that arise from excitati...

  9. Adaptive-optics optical coherence tomography for high-resolution and high-speed 3D retinal in vivo imaging

    OpenAIRE

    Zawadzki, Robert J.; Jones, Steven M.; Olivier, Scot S.; Zhao, Mingtao; Bower, Bradley A.; Izatt, Joseph A.; Choi, Stacey; Laut, Sophie; Werner, John S.

    2005-01-01

    We have combined Fourier-domain optical coherence tomography (FD-OCT) with a closed-loop adaptive optics (AO) system using a Hartmann-Shack wavefront sensor and a bimorph deformable mirror. The adaptive optics system measures and corrects the wavefront aberration of the human eye for improved lateral resolution (~4 ?m) of retinal images, while maintaining the high axial resolution (~6 ?m) of stand alone OCT. The AO-OCT instrument enables the three-dimensional (3D) visualization of different...

  10. Whole body small animal examination with a diffuse optical tomography instrument

    International Nuclear Information System (INIS)

    We developed a fluorescent diffuse optical tomography instrument in our laboratory to study in vivo tumour growth without any stress or damage for the animal. By taking into account optical heterogeneities, the reconstruction algorithm allows whole body small animal examination. Experimental results obtained with this system on phantoms and on mice deep lung tumours examination are presented in this paper

  11. Quantification of the optical surface reflection and surface roughness of articular cartilage using optical coherence tomography

    Energy Technology Data Exchange (ETDEWEB)

    Saarakkala, Simo; Wang Shuzhe; Huang Yanping; Zheng Yongping [Department of Health Technology and Informatics, Hong Kong Polytechnic University, Hong Kong (China)], E-mail: simo.saarakkala@uku.fi, E-mail: ypzheng@ieee.org

    2009-11-21

    Optical coherence tomography (OCT) is a promising new technique for characterizing the structural changes of articular cartilage in osteoarthritis (OA). The calculation of quantitative parameters from the OCT signal is an important step to develop OCT as an effective diagnostic technique. In this study, two novel parameters for the quantification of optical surface reflection and surface roughness from OCT measurements are introduced: optical surface reflection coefficient (ORC), describing the amount of a ratio of the optical reflection from cartilage surface with respect to that from a reference material, and OCT roughness index (ORI) indicating the smoothness of the cartilage surface. The sensitivity of ORC and ORI to detect changes in bovine articular cartilage samples after enzymatic degradations of collagen and proteoglycans using collagenase and trypsin enzymes, respectively, was tested in vitro. A significant decrease (p < 0.001) in ORC as well as a significant increase (p < 0.001) in ORI was observed after collagenase digestion. After trypsin digestion, no significant changes in ORC or ORI were observed. To conclude, the new parameters introduced were demonstrated to be feasible and sensitive to detect typical OA-like degenerative changes in the collagen network. From the clinical point of view, the quantification of OCT measurements is of great interest since OCT probes have been already miniaturized and applied in patient studies during arthroscopy or open knee surgery in vivo. Further studies are still necessary to demonstrate the clinical capability of the introduced parameters for naturally occurring early OA changes in the cartilage.

  12. 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. PMID:25780747

  13. Optic axis determination by fibre-based polarization-sensitive swept-source optical coherence tomography

    Energy Technology Data Exchange (ETDEWEB)

    Lu Zenghai; Kasaragod, Deepa K; Matcher, Stephen J, E-mail: z.lu@sheffield.ac.uk, E-mail: s.j.matcher@sheffield.ac.uk [Department of Materials Science and Engineering, Kroto Research Institute, University of Sheffield, North Campus, Broad Lane, Sheffield, S3 7HQ (United Kingdom)

    2011-02-21

    We describe a fibre-based variable-incidence angle (VIA) polarization-sensitive swept-source optical coherence tomography (PS-SS-OCT) system to determine the 3D optical axis of birefringent biological tissues. Single-plane VIA-PS-OCT is also explored which requires measurement of the absolute fast-axis orientation. A state-of-the-art PS-SS-OCT system with some improvements both in hardware and software was used to determine the apparent optical birefringence of equine tendon for a number of different illumination directions. Polar and azimuthal angles of cut equine tendon were produced by the VIA method and compared with the nominal values. A quarter waveplate (QWP) and equine tendon were used as test targets to validate the fast-axis measurements using the system. Polar and azimuthal angles of cut equine tendon broadly agreed with the expected values within about 8% of the nominal values. A theoretical and experimental analysis of the effect of the sample arm fibre on determination of optical axis orientation using a proposed definition based on the orientation of the eigenpolarization ellipse experimentally confirms that this algorithm only works correctly for special settings of the sample arm fibre. A proposed algorithm based on the angle between Stokes vectors on the Poincare sphere is confirmed to work for all settings of the sample arm fibre. A calibration procedure is proposed to remove the sign ambiguity of the measured orientation and was confirmed experimentally by using the QWP.

  14. Optic axis determination by fibre-based polarization-sensitive swept-source optical coherence tomography

    International Nuclear Information System (INIS)

    We describe a fibre-based variable-incidence angle (VIA) polarization-sensitive swept-source optical coherence tomography (PS-SS-OCT) system to determine the 3D optical axis of birefringent biological tissues. Single-plane VIA-PS-OCT is also explored which requires measurement of the absolute fast-axis orientation. A state-of-the-art PS-SS-OCT system with some improvements both in hardware and software was used to determine the apparent optical birefringence of equine tendon for a number of different illumination directions. Polar and azimuthal angles of cut equine tendon were produced by the VIA method and compared with the nominal values. A quarter waveplate (QWP) and equine tendon were used as test targets to validate the fast-axis measurements using the system. Polar and azimuthal angles of cut equine tendon broadly agreed with the expected values within about 8% of the nominal values. A theoretical and experimental analysis of the effect of the sample arm fibre on determination of optical axis orientation using a proposed definition based on the orientation of the eigenpolarization ellipse experimentally confirms that this algorithm only works correctly for special settings of the sample arm fibre. A proposed algorithm based on the angle between Stokes vectors on the Poincare sphere is confirmed to work for all settings of the sample arm fibre. A calibration procedure is proposed to remove the sign ambiguity of the measured orientation and was confirmed experimened orientation and was confirmed experimentally by using the QWP.

  15. Quantification of the optical surface reflection and surface roughness of articular cartilage using optical coherence tomography

    Science.gov (United States)

    Saarakkala, Simo; Wang, Shu-Zhe; Huang, Yan-Ping; Zheng, Yong-Ping

    2009-11-01

    Optical coherence tomography (OCT) is a promising new technique for characterizing the structural changes of articular cartilage in osteoarthritis (OA). The calculation of quantitative parameters from the OCT signal is an important step to develop OCT as an effective diagnostic technique. In this study, two novel parameters for the quantification of optical surface reflection and surface roughness from OCT measurements are introduced: optical surface reflection coefficient (ORC), describing the amount of a ratio of the optical reflection from cartilage surface with respect to that from a reference material, and OCT roughness index (ORI) indicating the smoothness of the cartilage surface. The sensitivity of ORC and ORI to detect changes in bovine articular cartilage samples after enzymatic degradations of collagen and proteoglycans using collagenase and trypsin enzymes, respectively, was tested in vitro. A significant decrease (p < 0.001) in ORC as well as a significant increase (p < 0.001) in ORI was observed after collagenase digestion. After trypsin digestion, no significant changes in ORC or ORI were observed. To conclude, the new parameters introduced were demonstrated to be feasible and sensitive to detect typical OA-like degenerative changes in the collagen network. From the clinical point of view, the quantification of OCT measurements is of great interest since OCT probes have been already miniaturized and applied in patient studies during arthroscopy or open knee surgery in vivo. Further studies are still necessary to demonstrate the clinical capability of the introduced parameters for naturally occurring early OA changes in the cartilage.

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

    Science.gov (United States)

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

    2005-08-01

    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. × 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.

  17. Investigation of pit formation in laser-irradiated multilayer thin films by using optical coherence tomography

    International Nuclear Information System (INIS)

    We propose a novel application of optical coherence tomography (OCT) to monitor pit formation in laser-irradiated optical storage materials. A multilayer optical storage recordable compact disk is composed of multiple layers, each of different structure. The disks were irradiated with a Q-Switched Nd:YAG laser with an energy of 373 mJ. Post-irradiated disks were evaluated by using OCT, and the images were compared with those obtained by using optical microscopy. Our results indicate that OCT can be a useful instrument for investigating pit formation in multilayer optical storage disks and might also provide information on ways to optimize optical memory technology.

  18. Optic disc topography in normal Indian eyes using spectral domain optical coherence tomography

    Directory of Open Access Journals (Sweden)

    Mansoori Tarannum

    2011-01-01

    Full Text Available Purpose: The aim was to study optic nerve head (ONH parameters in normal Indian eyes using spectral domain optical coherence tomography (OCT/scanning laser ophthamoscope (SLO. Materials and Methods: One hundred and fifty-seven eyes of 157 normal subjects of various age groups underwent ONH imaging with spectral OCT/SLO and the parameters obtained were correlated with disc size. The effect of age, gender, and refractive error on various ONH parameters were also studied. Results: The mean optic disc area was 3.36 ± 0.64 mm 2 (range, 2.13-5.08 mm 2 , mean rim area was 2.49 ± 0.58 mm 2 (range, 1.20-3.62 mm 2 , and mean cup area was 1.10 ± 0.75 mm 2 (range, 0-3.07 mm 2 . The disc area showed significant positive correlation with the rim area, cup area, horizontal cup disc ratio, vertical cup disc ratio, cup disc area ratio, mean cup depth, and maximum cup depth (P < 0.001. Neither gender nor refractive error showed any significant difference in various ONH parameters. ONH parameters did not show significant change with age except for rim area which declined with the advancing age (r = -0.25, P < 0.001. Conclusions: The quantitative measurement of ONH topography obtained with this study provides a normative database for an Indian population with spectral OCT/SLO. As optic disc area influences ONH topography, disc size should to be considered when evaluating optic disc for progressive optic neuropathies such as glaucoma.

  19. A unique stenosis in saphenous vein graft visualized by optical coherence tomography

    OpenAIRE

    Koeda, Yorihiko; Itoh, Tomonori; Fusazaki, Tetsuya; Nakamura, Motoyuki; Morino, Yoshihiro

    2013-01-01

    We present a case of a unique stenosis in a 12-year-old saphenous vein graft (SVG), to the right coronary artery, which was visualized by optical coherence tomography (OCT), before percutaneous coronary intervention. The patient was an 80-year-old man in whom the stenosis was documented by area-detector coronary computed tomography. OCT imaging demonstrated that the culprit lesion was a venous valve containing a thrombus before preintervention imaging. Coronary stenting was performed with a d...

  20. Time-gated optical projection tomography allows visualization of adult zebrafish internal structures

    OpenAIRE

    Foglia, Efrem Alessandro; Pistocchi, Anna Silvia; Cotelli, Franco

    2012-01-01

    Optical imaging through biological samples is compromised by tissue scattering and currently various approaches aim to overcome this limitation. In this paper we demonstrate that an all optical technique, based on non-linear upconversion of infrared ultrashort laser pulses and on multiple view acquisition, allows the reduction of scattering effects in tomographic imaging. This technique, namely Time-Gated Optical Projection Tomography (TGOPT), is used to reconstruct three dimensionally the in...

  1. Bilateral Vitreopapillary Traction Demonstrated by Optical Coherence Tomography Mistaken for Papilledema

    OpenAIRE

    Elizabeth Houle; Miller, Neil R.

    2012-01-01

    Purpose. The purpose of this study was to report a case of bilateral vitreopapillary traction, previously misdiagnosed as papilledema. Methods. A case report is presented of a 47-year-old woman with a prior diagnosis of papilledema, who is shown to have bilateral vitreopapillary traction rather than true optic disc swelling, confirmed by optical coherence tomography (OCT). Results. OCT showed vitreous traction surrounding the optic discs of both eyes. Fluorescein angiography demonstrated foca...

  2. Intraoperative handheld optical coherence tomography forward-viewing probe: physical performance and preliminary animal imaging

    OpenAIRE

    Sun, Cuiru; Lee, Kenneth K. C.; Vuong, Barry; Cusimano, Michael D.; Brukson, Alexander; Mauro, Antonio; Munce, Nigel; Courtney, Brian K.; Standish, Beau A.; Yang, Victor X. D.

    2012-01-01

    A prototype intraoperative hand-held optical coherence tomography (OCT) imaging probe was developed to provide micron resolution cross-sectional images of subsurface tissue during open surgery. This new ergonomic probe was designed based on electrostatically driven optical fibers, and packaged into a catheter probe in the form factor of clinically accepted Bayonet shaped neurosurgical probes. Optical properties of the probe were measured to have a ~20 ?m spot size, 5 mm working distance and ...

  3. Crystal Optical Properties of Inhomogeneous Plates and the Problems of Polarization Tomography of Photoelastic Materials

    Directory of Open Access Journals (Sweden)

    Kushnir O.

    2005-09-01

    Full Text Available Using the Jones matrix formalism, crystal optical properties of inhomogeneous material consisting of a pile of weakly birefringent plates are analysed in relation to the cell model adopted in polarization tomography of 3D dielectric tensor field in photoelastic media. It is shown that the material manifests in general an “apparent” optical gyration caused by different orientations of the plates. Relations between the polarimetric parameters and the dielectric tensor components are ascertained for the case of weak optical anisotropy.

  4. Excitation spectroscopy in multispectral optical fluorescence tomography: methodology, feasibility, and computer simulation studies

    OpenAIRE

    Chaudhari, Abhijit J.; Ahn, Sangtae; Levenson, Richard; Badawi, Ramsey D.; Cherry, Simon R.; Leahy, Richard M.

    2009-01-01

    Molecular probes used for in vivo Optical Fluorescence Tomography (OFT) studies in small animals are typically chosen such that their emission spectra lie in the 680–850 nm wavelength range. This is because tissue attenuation in this spectral band is relatively low, allowing optical photons even from deep sites in tissue to reach the animal surface, and consequently be detected by a CCD camera. The wavelength dependence of tissue optical properties within the 680–850 nm band can be exploi...

  5. Study of optical properties and proteoglycan content of tendons by polarization sensitive optical coherence tomography

    Science.gov (United States)

    Yang, Ying; Rupani, Asha; Bagnaninchi, Pierre; Wimpenny, Ian; Weightman, Alan

    2012-08-01

    The highly orientated collagen fibers in tendons play a critical role for transferring tensile stress, and they demonstrate birefringent optical properties. However, the influence that proteoglycans (PGs) have on the optical properties of tendons is yet to be fully elucidated. PGs are the essential components of the tendon extracellular matrix; the changes in their quantities and compositions have been associated with tendinopathies. In this study, polarization sensitive optical coherence tomography (PS-OCT) has been used to reveal the relationship between PG content/location and birefringence properties of tendons. Fresh chicken tendons were imaged at regular intervals by PS-OCT and polarization light microscopy during the extraction of PGs, using guanidine hydrochloride (GuHCl). Complementary time-lapsed images taken from the two modalities mutually demonstrated that the extraction of PGs disturbed the local organization of collagen bundles. This corresponded with a decrease in birefringence and associated banding pattern observed by PS-OCT. Furthermore, this study revealed there was a higher concentration of PGs in the outer sheath region than in the fascicles, and therefore the change in birefringence was reduced when extraction was performed on unsheathed tendons. The results provide new insights of tendon structure and the role of PGs on the structural stability of tendons, which also demonstrates the great potential for using PS-OCT as a diagnostic tool to examine tendon pathology.

  6. Optical imaging of oral pathological tissue using optical coherence tomography and synchrotron radiation computed microtomography

    Science.gov (United States)

    Cânj?u, Silvana; Todea, Carmen; Sinescu, Cosmin; Negrutiu, Meda L.; Duma, Virgil; M?nescu, Adrian; Topal?, Florin I.; Podoleanu, Adrian Gh.

    2013-06-01

    The efforts aimed at early diagnosis of oral cancer should be prioritized towards developing a new screening instrument, based on optical coherence tomography (OCT), to be used directly intraorally, able to perform a fast, real time, 3D and non-invasive diagnosis of oral malignancies. The first step in this direction would be to optimize the OCT image interpretation of oral tissues. Therefore we propose plastination as a tissue preparation method that better preserves three-dimensional structure for study by new optical imaging techniques. The OCT and the synchrotron radiation computed microtomography (micro-CT) were employed for tissue sample analyze. For validating the OCT results we used the gold standard diagnostic procedure for any suspicious lesion - histopathology. This is a preliminary study of comparing features provided by OCT and Micro-CT. In the conditions of the present study, OCT proves to be a highly promising imaging modality. The use of x-ray based topographic imaging of small biological samples has been limited by the low intrinsic x-ray absorption of non-mineralized tissue and the lack of established contrast agents. Plastination can be used to enhance optical imagies of oral soft tissue samples.

  7. Structural examination of easel paintings with optical coherence tomography.

    Science.gov (United States)

    Targowski, Piotr; Iwanicka, Magdalena; Tymi?ska-Widmer, Ludmi?a; Sylwestrzak, Marcin; Kwiatkowska, Ewa A

    2010-06-15

    Identification of the order, thickness, composition, and possibly the origin of the paint layers forming the structure of a painting, that is, its stratigraphy, is important in confirming its attribution and history as well as planning conservation treatments. The most common method of examination is analysis of a sample collected from the art object, both visually with a microscope and instrumentally through a variety of sophisticated, modern analytical tools. Because of its invasiveness, however, sampling is less than ideally compatible with conservation ethics; it is severely restricted with respect to the amount of material extirpated from the artwork. Sampling is also rather limited in that it provides only very local information. There is, therefore, a great need for a noninvasive method with sufficient in-depth resolution for resolving the stratigraphy of works of art. Optical coherence tomography (OCT) is a noninvasive, noncontact method of optical sectioning of partially transparent objects, with micrometer-level axial resolution. The method utilizes near-infrared light of low intensity (a few milliwatts) to obtain cross-sectional images of various objects; it has been mostly used in medical diagnostics. Through the serial collection of many such images, volume information may be extracted. The application of OCT to the examination of art objects has been in development since 2003. In this Account, we present a short introduction to the technique, briefly discuss the apparatus we use, and provide a paradigm for reading OCT tomograms. Unlike the majority of papers published previously, this Account focuses on one, very specific, use of OCT. We then consider two examples of successful, practical application of the technique. At the request of a conservation studio, the characteristics of inscriptions on two oil paintings, originating from the 18th and 19th centuries, were analyzed. In the first case, it was possible to resolve some questions concerning the history of the work. From an analysis of the positions of the paint layers involved in three inscriptions in relation to other strata of the painting, the order of events in its history was resolved. It was evident that the original text had been overpainted and that the other inscriptions were added later, thus providing convincing evidence as to the painting's true date of creation. In the second example, a painting was analyzed with the aim of confirming the possibility of forgery of the artist's signature, and evidence strongly supporting this supposition is presented. These two specific examples of successful use of the technique on paintings further demonstrate how OCT may be readily adaptable to other similar tasks, such as in the fields of forensic or materials science. In a synergistic approach, in which information is obtained with a variety of noninvasive techniques, OCT is demonstrably effective and offers great potential for further development. PMID:20043663

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

    International Nuclear Information System (INIS)

    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. (author)

  9. Functional imaging in bulk tissue specimens using optical emission tomography: fluorescence preservation during optical clearing

    Science.gov (United States)

    Sakhalkar, H. S.; Dewhirst, M.; Oliver, T.; Cao, Y.; Oldham, M.

    2007-04-01

    Optical emission computed tomography (optical-ECT) is a technique for imaging the three-dimensional (3D) distribution of fluorescent probes in biological tissue specimens with high contrast and spatial resolution. In optical-ECT, functional information can be imaged by (i) systemic application of functional labels (e.g. fluorophore labelled proteins) and/or (ii) endogenous expression of fluorescent reporter proteins (e.g. red fluorescent protein (RFP), green fluorescent protein (GFP)) in vivo. An essential prerequisite for optical-ECT is optical clearing, a procedure where tissue specimens are made transparent to light by sequential perfusion with fixing, dehydrating and clearing agents. In this study, we investigate clearing protocols involving a selection of common fixing (4% buffered paraformaldehyde (PFA), methanol and ethanol), dehydrating (methanol and ethanol) and clearing agents (methyl salicylate and benzyl-alcohol-benzyl-benzoate (BABB)) in order to determine a 'fluorescence friendly' clearing procedure. Cell culture experiments were employed to optimize the sequence of chemical treatments that best preserve fluorescence. Texas red (TxRed), fluorescein isothiocyanate (FITC), RFP and GFP were tested as fluorophores and fluorescent reporter proteins of interest. Fluorescent and control cells were imaged on a microscope using a DSred2 and FITC filter set. The most promising clearing protocols of cell culture experiments were applied to whole xenograft tumour specimens, to test their effectiveness in large unsectioned samples. Fluorescence of TxRed/FITC fluorophores was not found to be significantly affected by any of the test clearing protocols. RFP and GFP fluorescence, however, was found to be significantly greater when cell fixation was in ethanol. Fixation in either PFA or methanol resulted in diminished fluorescence. After ethanol fixation, the RFP and GFP fluorescence proved remarkably robust to subsequent exposure to either methyl salicylate or BABB. The optimized optical clearing procedure of ethanol fixation followed by methyl salicylate clearing preserved the fluorescence of constitutive RFP in whole xenograft tumour specimens, about 1 cc in dimension, indicating successful extension from cell plating experiments to whole tissue samples. Finally, the feasibility of imaging the 3D distribution of viable tumour cells (as indicated by the RFP emission) is demonstrated by optical-ECT imaging of cleared xenograft tumours using an in-house system.

  10. Optic nerve head analysis of superior segmental optic hypoplasia using Heidelberg retina tomography

    Directory of Open Access Journals (Sweden)

    Atsushi Miki

    2010-10-01

    Full Text Available Atsushi Miki1,2, Motohiro Shirakashi1, Kiyoshi Yaoeda1, Atsushi Fukushima1, Mineo Takagi1, Haruki Abe11Division of Ophthalmology and Visual Sciences, Niigata University Graduate School of Medical and Dental Sciences, Niigata, 2Department of Ophthalmology, Kawasaki Medical School, Okayama, JapanPurpose: To evaluate the optic disc characteristics of eyes with superior segmental optic hypoplasia (SSOH using the Heidelberg retina tomograph (HRT.Patients and methods: Thirteen eyes of 13 Japanese patients with SSOH were studied with the HRT (software version: 3.0. The group included six males and seven females, with a mean age of 34.7 years. Six optic disc parameters in the six sectors derived from the patients with SSOH were compared with those of 13 eyes of 13 normal controls. In addition, the diagnostic classification performance of the Frederick S Mikelberg (FSM discriminant function, glaucoma probability score (GPS, and Moorfields regression analysis (MRA were assessed.Results: When compared with normal subjects, many of the optic disc parameters were significantly altered in SSOH in the superior sectors. The area under the curve (AUC for the receiver operating characteristic was 0.932 for the rim area, 0.926 for the cup-to-disc area ratio, and 0.882 for the cup shape measure. Among the HRT parameters, the largest AUC (0.988 was found for the cup shape measure in the nasal superior segment. The proportion classified as outside normal limits by the FSM discriminant function was 92.3% (12 eyes. For GPS, six eyes (46.2% were classified as outside normal limits. For MRA, when borderline cases were considered test-negative or test-positive, 10 eyes (76.9% or 11 eyes (84.6% were classified as outside normal limits, respectively. The AUCs were 0.976 for the FSM discriminant function, 0.914 for the MRA overall classification, and 0.710 for the GPS overall classification.Conclusions: In eyes with SSOH, there is a significant thinning of the rim, especially in the nasal superior sector. Approximately half of the eyes with SSOH were classified as abnormal using indices developed for detecting glaucoma, but the sectorial analysis revealed that the affected sectors were different from those of glaucoma. Optic nerve head measurements using the HRT may be useful in evaluating the optic disc characteristics in eyes with SSOH.Keywords: superior segmental optic hypoplasia, Heidelberg retina tomography

  11. Quantification of the optical surface reflection and surface roughness of articular cartilage using optical coherence tomography

    International Nuclear Information System (INIS)

    Optical coherence tomography (OCT) is a promising new technique for characterizing the structural changes of articular cartilage in osteoarthritis (OA). The calculation of quantitative parameters from the OCT signal is an important step to develop OCT as an effective diagnostic technique. In this study, two novel parameters for the quantification of optical surface reflection and surface roughness from OCT measurements are introduced: optical surface reflection coefficient (ORC), describing the amount of a ratio of the optical reflection from cartilage surface with respect to that from a reference material, and OCT roughness index (ORI) indicating the smoothness of the cartilage surface. The sensitivity of ORC and ORI to detect changes in bovine articular cartilage samples after enzymatic degradations of collagen and proteoglycans using collagenase and trypsin enzymes, respectively, was tested in vitro. A significant decrease (p < 0.001) in ORC as well as a significant increase (p < 0.001) in ORI was observed after collagenase digestion. After trypsin digestion, no significant changes in ORC or ORI were observed. To conclude, the new parameters introduced were demonstrated to be feasible and sensitive to detect typical OA-like degenerative changes in the collagen network. From the clinical point of view, the quantification of OCT measurements is of great interest since OCT probes have been already miniaturized and applied in patient studies during arthroscopy or open atient studies during arthroscopy or open knee surgery in vivo. Further studies are still necessary to demonstrate the clinical capability of the introduced parameters for naturally occurring early OA changes in the cartilage.

  12. Quantum-state tomography for optical polarization with arbitrary photon numbers

    Science.gov (United States)

    Klimov, A. B.; Romero, J. L.; Wallentowitz, S.

    2014-02-01

    A scheme for quantum-state tomography is presented that can be performed for polarized light with an arbitrary photon-number distribution. The proposed method fills the gap between existing polarization-tomography schemes for single-photon states and for optical fields with very large photon numbers. It consists of an optical homodyne setup triggered by the outcome of a single-photon counting module. The configuration space of polarization is parametrized by Euler angles and by an additional interference parameter, whose assessment requires conditional homodyne measurements.

  13. Wavelet-domain de-noising of optical coherent tomography data for biomedical applications

    Science.gov (United States)

    Zaytsev, Kirill I.; Kudrin, Konstantin G.; Chernomyrdin, Nikita V.; Khorokhorov, Alexey M.; Prytov, Alexander B.; Dolganova, Irina N.; Perchik, Alexey V.; Reshetov, Igor V.; Yurchenko, Stanislav O.

    2015-01-01

    Optical coherent tomography (OCT) is a rapidly developing method of fundamental and applied research. Detection and processing of OCT images is a very important problem of applied physics and optical signal processing. In the present paper we are demonstrating the ability for effective wavelet-domain de-noising of OCT images. We are realizing an algorithm for wavelet-domain de-noising of OCT data and implementing it for the purpose of studying test samples and for in vivo nail tomography. High de-noising efficiency with no significant losses of information about the internal sample structure is observed.

  14. The correlation between rat retinal nerve fiber layer thickness around optic disc by using optical coherence tomography and histological measurements

    OpenAIRE

    Ju-Fang Huang; Hui-Min Yu; Lei Shang,; Ruo-Fei Ma; Ngobe Akume Cynthia; Yan-Qun Cao; Jia Luo; Le-Ping Zeng; Dan Chen; Kun Xiong

    2013-01-01

    AIM:To explore the correlation between the retinal nerve fiber layer (RNFL) thickness by using optical coherence tomography (OCT) and by histological measurements in normal adult rats and optic nerve transected rats.METHODS:The RNFL thickness of 36 rats was scanned in a circle 3.46mm far from the optic disc by OCT. The two experimental groups were the normal group (n=20 rats) and the optic nerve transected group (n=16 rats). The latter group included 4 groups (n=4/group) surviving for 1 day, ...

  15. Development of CCD-based optical computed tomography and comparison with single-beam optical CT scanner

    Science.gov (United States)

    Chang, Y. J.

    2015-01-01

    This study reports on the development of CCD-based optical computed tomography (CT) CT-s2. A commercially available 10× fast optical computed tomography scanner (OCTOPUSTM-10X, MGS Research, Inc., Madison, CT, USA) was used for comparison. NIPAM polymer gel dosimeter was used to validate the performance of CT-s2. The gamma pass rate can reach 96.00% when using a 3% dose difference and 3 mm dose-to-agreement criteria. The results of CT-s2 are as good as those of the single-beam optical-CT scanner, but the scanning time of CT-s2 is only one-tenth of that of the single-beam optical-CT scanner.

  16. Imaging cone photoreceptors in three dimensions and in time using ultrahigh resolution optical coherence tomography with adaptive optics

    OpenAIRE

    Kocaoglu, Omer P.; Lee, Sangyeol; Jonnal, Ravi S.; Wang, Qiang; Herde, Ashley E.; Derby, Jack C.; Gao, Weihua; Miller, Donald T.

    2011-01-01

    Cone photoreceptors in the living human eye have recently been imaged with micron-scale resolution in all three spatial dimensions using adaptive optics optical coherence tomography. While these advances have allowed non-invasive study of the three-dimensional structure of living human cones, studies of their function and physiology are still hampered by the difficulties to monitor the same cells over time. The purpose of this study is to demonstrate the feasibility of cone monitoring using u...

  17. 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.

  18. Adaptive optics-assisted optical coherence tomography for imaging of patients with age related macular degeneration

    Science.gov (United States)

    Sudo, Kenta; Cense, Barry

    2013-03-01

    We developed an optical coherence tomography (OCT) prototype with a sample arm that uses a 3.4 mm beam, which is considerably larger than the 1.2 to 1.5 mm beam that is used in commercialized OCT systems. The system is equipped with adaptive optics (AO), and to distinguish it from traditional AO-OCT systems with a larger 6 mm beam we have coined this concept AO-assisted OCT. Compared to commercialized OCT systems, the 3.4 mm aperture combined with AO improves light collection efficiency and imaging lateral resolution. In this paper, the performance of the AOa-OCT system was compared to a standard OCT system and demonstrated for imaging of age-related macular degeneration (AMD). Measurements were performed on the retinas of three human volunteers with healthy eyes and on one eye of a patient diagnosed with AMD. The AO-assisted OCT system imaged retinal structures of healthy human eyes and a patient eye affected by AMD with higher lateral resolution and a 9° by 9° field of view. This combination of a large isoplanatic patch and high lateral resolution can be expected to fill a gap between standard OCT with a 1.2 mm beam and conventional AO-OCT with a 6 mm beam and a 1.5° by 1.5° isoplanatic patch.

  19. Assessing near infrared optical properties of ceramic orthodontic brackets using cross-polarization optical coherence tomography.

    Science.gov (United States)

    Isfeld, Darren M; Aparicio, Conrado; Jones, Robert S

    2014-04-01

    Secondary decay (caries) under ceramic orthodontic brackets remains a significant dental problem and near infrared cross-polarization optical coherence tomography (CP-OCT) has the potential to detect underlying demineralization. The purpose of this study was to determine the effect of crystalline structure and chemical composition of ceramic brackets on CP-OCT imaging. Four ceramic brackets types, which were divided into monocrystalline and polycrystalline, were examined using CP-OCT. The results of this study demonstrated that the crystallinity of the ceramic brackets affected the 1310 nm CP-OCT imaging with the greatest attenuation seen in polycrystalline alumina brackets. The alumina polycrystalline bracket materials had significantly higher attenuation and scattering than alumina monocrystalline brackets (p?bracket base morphology and composition affected NIR light attenuation. There was considerable attenuation in bracket bases that contained additive zirconium spheres (?30 µm) and this alteration was significantly greater than the jagged alumina crystallographic alterations found in the other bracket systems (p?ceramic brackets; however, further investigation into the optical effects of resin integration in the base portion of the brackets is warranted. PMID:24106170

  20. Optical biomarkers for breast cancer derived from dynamic diffuse optical tomography.

    Science.gov (United States)

    Flexman, Molly L; Kim, Hyun K; Gunther, Jacqueline E; Lim, Emerson A; Alvarez, Maria C; Desperito, Elise; Kalinsky, Kevin; Hershman, Dawn L; Hielscher, Andreas H

    2013-09-01

    Diffuse optical tomography (DOT) is a noninvasive, nonionizing imaging modality that uses near-infrared light to visualize optically relevant chromophores. A recently developed dynamic DOT imaging system enables the study of hemodynamic effects in the breast during a breath-hold. Dynamic DOT imaging was performed in a total of 21 subjects (age 54±10??years) including 3 healthy subjects and 18 subjects with benign (n=8) and malignant (n=14) masses. Three-dimensional time-series images of the percentage change in oxygenated and deoxygenated hemoglobin concentrations ([HbO2] and [Hb]) from baseline are obtained over the course of a breath-hold. At a time point of 15 s following the end of the breath-hold, [Hb] in healthy breasts has returned to near-baseline values (1.6%±0.5%), while tumor-bearing breasts have increased levels of [Hb] (6.8%±3.6%, p<0.01). Further, healthy subjects have a higher correlation between the breasts over the course of the breath-hold as compared with the subjects with breast cancer (healthy: 0.96±0.02; benign: 0.89±0.02; malignant: 0.78±0.23, p<0.05). Therefore this study shows that dynamic features extracted from DOT measurements can differentiate healthy and diseased breast tissues. These features provide a physiologic method for identifying breast cancer without the need for ionizing radiation. PMID:24048367

  1. Theoretical study of Acousto-optical coherence tomography using random phase jumps on US and light

    CERN Document Server

    Gross, Michel; Ramaz, François; Farahi, Salma; Boccara, A C

    2011-01-01

    Acousto-optical coherence tomography (AOCT) is a variant of acousto-optic imaging (also called ultrasonic modulation imaging) that makes it possible to get the z resolution with acoustic and optic continuous wave beams. We describe here theoretically the AOCT effect, and we show that the acousto-optic "tagged photons" remain coherent if they are generated within a specific z region of the sample. We quantify the z selectivity for both the "tagged photon" field and for the Lesaffre et al. [Opt. Express 17, 18211 (2009)] photorefractive signal.

  2. Correlative Cryo-electron Tomography and Optical Microscopy of Cells

    OpenAIRE

    Zhang, Peijun

    2013-01-01

    The biological processes occurring in a cell are complex and dynamic, and to achieve a comprehensive understanding of the molecular mechanisms underlying these processes, both temporal and spatial information is required. While cryo-electron tomography (cryoET) provides three-dimensional (3D) still pictures of near-native state cells and organelles at molecular resolution, fluorescence light microscopy (fLM) offers movies of dynamic cellular processes in living cells. Combining and integratin...

  3. Mapping coherence in measurement via full quantum tomography of a hybrid optical detector

    CERN Document Server

    Zhang, Lijian; Datta, Animesh; Puentes, Graciana; Lundeen, Jeff S; Jin, Xian-Min; Smith, Brian J; Plenio, Martin B; Walmsley, Ian A

    2012-01-01

    Quantum states and measurements exhibit wave-like --- continuous, or particle-like --- discrete, character. Hybrid discrete-continuous photonic systems are key to investigating fundamental quantum phenomena, generating superpositions of macroscopic states, and form essential resources for quantum-enhanced applications, e.g. entanglement distillation and quantum computation, as well as highly efficient optical telecommunications. Realizing the full potential of these hybrid systems requires quantum-optical measurements sensitive to complementary observables such as field quadrature amplitude and photon number. However, a thorough understanding of the practical performance of an optical detector interpolating between these two regions is absent. Here, we report the implementation of full quantum detector tomography, enabling the characterization of the simultaneous wave and photon-number sensitivities of quantum-optical detectors. This yields the largest parametrization to-date in quantum tomography experiments...

  4. Non-uniqueness in fluorescence-enhanced continuous wave diffuse optical tomography

    International Nuclear Information System (INIS)

    Fluorescence imaging is an attractive imaging modality for understanding biological mechanisms. Among such techniques, continuous wave fluorescence-enhanced diffuse optical tomography (CW-fDOT) is interesting since it is adapted to CCD cameras which allow non-contact measurements on a large number of detection elements for low cost. Here, by extending the derivations previously applied to continuous wave diffuse optical tomography (CW-DOT), we demonstrate that multiple optical configurations may lead to the same sets of optical measurements. We first explain in a ideal case and then in a 'real-world' example when such situations happen. Therefore, one cannot absolutely quantify the fluorescence amount from CW-fDOT measurements without adding priors

  5. Small field dose delivery evaluations using cone beam optical computed tomography-based polymer gel dosimetry

    OpenAIRE

    Olding Timothy; Holmes Oliver; DeJean Paul; McAuley Kim; Nkongchu Ken; Santyr Giles; Schreiner L

    2011-01-01

    This paper explores the combination of cone beam optical computed tomography with an N-isopropylacrylamide (NIPAM)-based polymer gel dosimeter for three-dimensional dose imaging of small field deliveries. Initial investigations indicate that cone beam optical imaging of polymer gels is complicated by scattered stray light perturbation. This can lead to significant dosimetry failures in comparison to dose readout by magnetic resonance imaging (MRI). For example, only 60% of the voxels f...

  6. Advanced 3D-reconstruction of biological specimen monitored by non-invasive optical tomography

    International Nuclear Information System (INIS)

    Imaging of intricate and delicate subcellular structures along with reliable 3D-reconstruction of cells and tissues may be achieved on the basis of confocal laser scanning microscopy (optical tomography) provided that certain criteria such as proper loading of fluorescent dyes, image acquisition under defined electro-optical conditions, suitable image pre- and postprocessing, etc., are taken into account prior to volume- or surface-rendering for 3D-visualization. (author)

  7. Resting-state functional connectivity in the human brain revealed with diffuse optical tomography

    OpenAIRE

    White, Brian R.; Snyder, Abraham Z.; Cohen, Alexander L.; Petersen, Steven E.; Raich-le, Marcus E.; Schlaggar, Bradley L.; Culver, Joseph P.

    2009-01-01

    Mapping resting-state networks allows insight into the brain's functional architecture and physiology and has rapidly become important in contemporary neuroscience research. Diffuse optical tomography (DOT) is an emerging functional neuroimaging technique with the advantages, relative to functional magnetic resonance imaging (fMRI), of portability and the ability to simultaneously measure both oxy- and deoxy-hemoglobin. Previous optical studies have evaluated the temporal features of spontane...

  8. Cerebral blood flow imaged with ultrahigh-resolution optical coherence angiography and Doppler tomography

    OpenAIRE

    Ren, Hugang; Du, Congwu; Pan, Yingtian

    2012-01-01

    Speckle contrast based optical coherence angiography (OCA) and optical coherence Doppler tomography (ODT) have been applied to image cerebral blood flow previously. However, the contrast mechanisms of these two methods are not fully studied. Here, we present both flow phantom and in vivo animal experiments using ultrahigh-resolution OCA (?OCA) and ODT (?ODT) to investigate the flow sensitivity differences between these two methods. Our results show that the high sensitivity of ?OCA for vis...

  9. In vivo volumetric imaging of human retinal circulation with phase-variance optical coherence tomography

    OpenAIRE

    Kim, Dae Yu; Fingler, Jeff; Werner, John S.; Schwartz, Daniel M.; Fraser, Scott E.; Zawadzki, Robert J.

    2011-01-01

    We present in vivo volumetric images of human retinal micro-circulation using Fourier-domain optical coherence tomography (Fd-OCT) with the phase-variance based motion contrast method. Currently fundus fluorescein angiography (FA) is the standard technique in clinical settings for visualizing blood circulation of the retina. High contrast imaging of retinal vasculature is achieved by injection of a fluorescein dye into the systemic circulation. We previously reported phase-variance optical co...

  10. Measurement of cerebral microvascular compliance in a model of atherosclerosis with optical coherence tomography

    OpenAIRE

    Baraghis, E.; Bolduc, V.; Lefebvre, J.; Srinivasan, V. J.; Boudoux, C.; Thorin, E.; Lesage, F.

    2011-01-01

    Optical coherence tomography (OCT) has recently been used to produce 3D angiography of microvasculature and blood flow maps of large vessels in the rodent brain in-vivo. However, use of this optical method for the study of cerebrovascular disease has not been fully explored. Recent developments in neurodegenerative diseases has linked common cardiovascular risk factors to neurodegenerative risk factors hinting at a vascular hypothesis for the development of the latter. Tools for studying cere...

  11. Noninvasive Evaluation of Nuclear Morphometry in Breast Lesions Using Multispectral Diffuse Optical Tomography

    OpenAIRE

    Hajihashemi, Mohammad Reza; Grobmyer, Stephen R.; Al-quran, Samer Z.; Jiang, Huabei

    2012-01-01

    Breast cancer is the most prevalent cancer and the main cause of cancer-related death in women worldwide. There are limitations associated with the existing clinical tools for breast cancer detection and alternative modalities for early detection and classification of breast cancer are urgently needed. Here we describe an optical imaging technique, called multispectral diffuse optical tomography (DOT), and demonstrate its ability of non-invasively evaluating nuclear morphometry for differenti...

  12. Tumor characterization in small animals using magnetic resonance-guided dynamic contrast enhanced diffuse optical tomography

    OpenAIRE

    Lin, Yuting; Thayer, Dave; Nalcioglu, Orhan; Gulsen, Gultekin

    2011-01-01

    We present a magnetic resonance (MR)-guided near-infrared dynamic contrast enhanced diffuse optical tomography (DCE-DOT) system for characterization of tumors using an optical contrast agent (ICG) and a MR contrast agent [Gd-diethylenetriaminepentaacetic acid (DTPA)] in a rat model. Both ICG and Gd-DTPA are injected and monitored simultaneously using a combined MRI-DOT system, resulting in accurate co-registration between two imaging modalities. Fisher rats bearing R3230 breast tumor are imag...

  13. Swept source / Fourier domain polarization sensitive optical coherence tomography with a passive polarization delay unit

    OpenAIRE

    Baumann, Bernhard; Choi, Woojhon; Potsaid, Benjamin; Huang, David; Duker, Jay S.; Fujimoto, James G.

    2012-01-01

    Polarization sensitive optical coherence tomography (PS-OCT) is a functional imaging method that provides additional contrast using the light polarizing properties of a sample. This manuscript describes PS-OCT based on ultrahigh speed swept source / Fourier domain OCT operating at 1050nm at 100kHz axial scan rates using single mode fiber optics and a multiplexing approach. Unlike previously reported PS-OCT multiplexing schemes, the method uses a passive polarization delay unit and does not re...

  14. Fluorescence-based surface magnifying chromoendoscopy and optical coherence tomography endoscope

    OpenAIRE

    Wall, R. Andrew; Barton, Jennifer K.

    2012-01-01

    A side-viewing, 2.3-mm diameter, surface magnifying chromoendoscopy-optical coherence tomography (SMC-OCT) endoscope has been designed for simultaneous, nondestructive surface fluorescence visualization and cross-sectional imaging. We apply this endoscope to in vivo examination of the mouse colon. A 30,000 element fiber bundle is combined with single mode fibers, for SMC and OCT imaging, respectively. The distal optics consist of a gradient-index lens and spacer to provide a 1× magnification...

  15. Design and Construction of an Optical Computed Tomography Scanner for Polymer Gel Dosimetry Application

    OpenAIRE

    Zakariaee, Seyed Salman; Mesbahi, Asghar; Keshtkar, Ahmad; Azimirad, Vahid

    2014-01-01

    Polymer gel dosimeter is the only accurate three dimensional (3D) dosimeter that can measure the absorbed dose distribution in a perfect 3D setting. Gel dosimetry by using optical computed tomography (OCT) has been promoted by several researches. In the current study, we designed and constructed a prototype OCT system for gel dosimetry. First, the electrical system for optical scanning of the gel container using a Helium-Neon laser and a photocell was designed and constructed. Then, the mecha...

  16. High speed spectral domain polarization sensitive optical coherence tomography of the human retina

    OpenAIRE

    Go?tzinger, Erich; Pircher, Michael; Hitzenberger, Christoph K.

    2005-01-01

    We developed a high-speed polarization sensitive optical coherence tomography (PS-OCT) system for retinal imaging based on spectral domain OCT. The system uses two spectrometers, one for each polarization channel, that operate in parallel at 20000 A-lines/s each. It provides reflectivity, retardation, and cumulative optic axis orientation simultaneously. We present our instrument and discuss the requirements for the alignment of the two spectrometers specific for our setup. We show 2D spectra...

  17. Hierarchical Bayesian regularization of reconstructions for diffuse optical tomography using multiple priors

    OpenAIRE

    Abdelnour, Farras; Genovese, Christopher; Huppert, Theodore

    2010-01-01

    Diffuse optical tomography (DOT) is a non-invasive brain imaging technique that uses low-levels of near-infrared light to measure optical absorption changes due to regional blood flow and blood oxygen saturation in the brain. By arranging light sources and detectors in a grid over the surface of the scalp, DOT studies attempt to spatially localize changes in oxy- and deoxy-hemoglobin in the brain that result from evoked brain activity during functional experiments. However, the reconstruction...

  18. Crystal Optical Properties of Inhomogeneous Plates and the Problems of Polarization Tomography of Photoelastic Materials

    OpenAIRE

    Kushnir O.; Nek P.; Vlokh R.; Kukhtarev N

    2007-01-01

    Using the Jones matrix formalism, crystal optical properties of inhomogeneous material consisting of a pile of weakly birefringent plates are analysed in relation to the cell model adopted in polarization tomography of 3D dielectric tensor field in photoelastic media. It is shown that the material manifests in general an "apparent" optical gyration caused by different orientations of the plates. Relations between the polarimetric parameters and the dielectric tensor componen...

  19. Optimal Analysis Method for Dynamic Contrast-Enhanced Diffuse Optical Tomography

    OpenAIRE

    Michael Ghijsen; Yuting Lin; Mitchell Hsing; Orhan Nalcioglu; Gultekin Gulsen

    2011-01-01

    Diffuse Optical Tomography (DOT) is an optical imaging modality that has various clinical applications. However, the spatial resolution and quantitative accuracy of DOT is poor due to strong photon scatting in biological tissue. Structural a priori information from another high spatial resolution imaging modality such as Magnetic Resonance Imaging (MRI) has been demonstrated to significantly improve DOT accuracy. In addition, a contrast agent can be used to obtain differential absorption imag...

  20. Extracting structural features of rat sciatic nerve using polarization-sensitive spectral domain optical coherence tomography

    OpenAIRE

    Islam, M. S.; Oliveira, M. C.; Wang, Y.; Henry, F. P.; Randolph, M. A.; Park, B. H.; Boer, J. F.

    2012-01-01

    We present spectral domain polarization-sensitive optical coherence tomography (SD PS-OCT) imaging of peripheral nerves. Structural and polarization-sensitive OCT imaging of uninjured rat sciatic nerves was evaluated both qualitatively and quantitatively. OCT and its functional extension, PS-OCT, were used to image sciatic nerve structure with clear delineation of the nerve boundaries to muscle and adipose tissues. A long-known optical effect, bands of Fontana, was also observed. Postprocessi...

  1. Multisensor coordinate measuring technology. Dimensional metrology using optics, tactile sensing and X-ray tomography

    International Nuclear Information System (INIS)

    This booklet gives a comprehensive and lucid introduction to the technical fundamentals of multisensor coordinate measuring technology as available at the time of writing (2013). Its emphasis is on optic, tactile and X-ray tomography sensors, but it also provides in-depth coverage of important aspects of measuring device technology and its applications as well as accuracy and economic efficiency.

  2. Improved reconstructions and generalized filtered back projection for optical projection tomography.

    Science.gov (United States)

    Birk, Udo Jochen; Darrell, Alex; Konstantinides, Nikos; Sarasa-Renedo, Ana; Ripoll, Jorge

    2011-02-01

    Optical projection tomography (OPT) is a noninvasive imaging technique that enables imaging of small specimens (Parhyale hawaiensis embedded in glycerol and in sea water. Successful reconstructions of fluorescence and absorption OPT images have been obtained for weakly scattering specimens embedded in media with nonmatched refractive index, thus advancing OPT toward routine in vivo imaging. PMID:21283227

  3. Evaluation of central serous retinopathy with en face optical coherence tomography

    OpenAIRE

    Velthoven, M. E.; Verbraak, F. D.; Garcia, P. M.; Schlingemann, R. O.; Rosen, R. B.; Smet, M. D.

    2005-01-01

    Background: The diagnosis of idiopathic central serous retinopathy (CSR) is usually based on biomicroscopy and fluorescein angiography (FA). The optical coherence tomography (OCT) ophthalmoscope produces en face OCT scans (OCT C-scans) and provides additional information not readily available by conventional imaging techniques. The authors describe the characteristic features observed in patients with a clinical diagnosis of CSR using the OCT ophthalmoscope.

  4. SIMULATION STUDY FOR GASEOUS FLUXES FROM AN AREA SOURCE USING COMPUTED TOMOGRAPHY AND OPTICAL REMOTE SENSING

    Science.gov (United States)

    The paper presents a new approach to quantifying emissions from fugitive gaseous air pollution sources. Computed tomography (CT) and path-integrated optical remote sensing (PI-ORS) concentration data are combined in a new field beam geometry. Path-integrated concentrations are ...

  5. Optical Coherence Tomography and Biomolecular Imaging with Coherent Raman Scattering Microscopy

    DEFF Research Database (Denmark)

    Andersson-Engels, Stefan; Andersen, Peter E.

    2014-01-01

    The Special Section on Selected Topics in Biophotonics: Optical Coherence Tomography and Biomolecular Imaging with Coherent Raman Scattering Microscopy comprises two invited review papers and several contributed papers from the summer school Biophotonics ’13, as well as contributed papers within this general scope.

  6. Polarization Sensitive Optical Coherence Tomography for Blood Glucose Monitoring in Human Subjects

    CERN Document Server

    Solanki, Jitendra; Sen, Pratima; Andrews, Joseph Thomas

    2012-01-01

    A device based on Polarization sensitive optical coherence tomography is developed to monitor blood glucose levels in human subjects. The device was initially tested with tissue phantom. The measurements with human subjects for various glucose concentration levels are found to be linearly dependent on the degree of circular polarization obtainable from the PS-OCT.

  7. Quantitative comparison of analysis methods for spectroscopic optical coherence tomography: reply to comment

    OpenAIRE

    Bosschaart, Nienke; Leeuwen, Ton G.; Aalders, Maurice C. G.; Faber, Dirk J.

    2014-01-01

    We reply to the comment by Kraszewski et al on “Quantitative comparison of analysis methods for spectroscopic optical coherence tomography.” We present additional simulations evaluating the proposed window function. We conclude that our simulations show good qualitative agreement with the results of Kraszewski, in support of their conclusion that SOCT optimization should include window shape, next to choice of window size and analysis algorithm.

  8. ENHANCED DEPTH IMAGING SPECTRAL-DOMAIN OPTICAL COHERENCE TOMOGRAPHY FINDINGS IN CHOROIDAL NEUROFIBROMATOSIS

    Science.gov (United States)

    Rao, Rajesh C.; Choudhry, Netan

    2015-01-01

    We report multimodal imaging findings, including enhanced depth imaging-optical coherence tomography, in an affected child with choroidal neurofibromatosis. We identify novel features such as choroidal vessel compression from NF1-related choroidal nodules and an increased subfoveal choroidal thickness. This is the first report to use EDI-OCT to analyze choroidal features in neurofibromatosis type-1. PMID:25153660

  9. Spontaneous coronary artery dissection treated with bioresorbable vascular scaffolds guided by optical coherence tomography.

    Science.gov (United States)

    Cockburn, James; Yan, Warren; Bhindi, Ravinay; Hansen, Peter

    2014-11-01

    Spontaneous coronary artery dissection (SCAD) is an uncommon cause of acute coronary syndromes. We report the first case, to our knowledge, of SCAD in an active fit man. We treated this patient with novel bioresorbable vascular scaffold, guided by optical coherence tomography. PMID:25442447

  10. Erosion/malapposition of a sirolimus eluting stent – Optical coherence tomography image – A case report

    OpenAIRE

    Sengottuvelu, G.

    2012-01-01

    The presence of erosion/malapposition of a Sirolimus eluting stent was clearly visualized using Optical Coherence Tomography (OCT) imaging. The presence of erosion/malapposition and the absence of neointimal hyperplasia after 10 months of sirolimus eluting stent could constitute a potential thrombogenic substrate for late stent thrombosis.

  11. An Efficient Approach for Optical Radiative Transfer Tomography using the Spherical Harmonics Discrete Ordinates Method

    CERN Document Server

    Levis, Aviad; Aides, Amit; Davis, Anthony B

    2015-01-01

    This paper introduces a method to preform optical tomography, using 3D radiative transfer as the forward model. We use an iterative approach predicated on the Spherical Harmonics Discrete Ordinates Method (SHDOM) to solve the optimization problem in a scalable manner. We illustrate with an application in remote sensing of a cloudy atmosphere.

  12. Polarization sensitive optical coherence tomography of melanin provides tissue inherent contrast based on depolarization

    OpenAIRE

    Baumann, Bernhard; Baumann, Stefan O.; Konegger, Thomas; Pircher, Michael; Go?tzinger, Erich; Sattmann, Harald; Litschauer, Marco; Hitzenberger, Christoph K.

    2010-01-01

    Polarization sensitive optical coherence tomography (PS-OCT) was used to investigate the polarization properties of melanin. Measurements in samples with varying melanin concentrations revealed polarization scrambling, i.e. depolarization. The results indicate that the depolarizing appearance of pigmented structures like, for instance, the retinal pigment epithelium (RPE) is likely to be caused by the melanin granules contained in these cells.

  13. Polarization sensitive optical coherence tomography of melanin provides tissue inherent contrast based on depolarization

    Science.gov (United States)

    Baumann, Bernhard; Baumann, Stefan O.; Konegger, Thomas; Pircher, Michael; Götzinger, Erich; Sattmann, Harald; Litschauer, Marco; Hitzenberger, Christoph K.

    2010-02-01

    Polarization sensitive optical coherence tomography (PS-OCT) was used to investigate the polarization properties of melanin. Measurements in samples with varying melanin concentrations revealed polarization scrambling, i.e. depolarization. The results indicate that the depolarizing appearance of pigmented structures like, for instance, the retinal pigment epithelium (RPE) is likely to be caused by the melanin granules contained in these cells.

  14. 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.

  15. Retinal imaging with a combined adaptive optics/optical coherence tomography and adaptive optics/scanning laser ophthalmoscopy system

    Science.gov (United States)

    Zawadzki, Robert J.; Jones, Steven M.; Pilli, Suman; Kim, Dae Yu; Olivier, Scot S.; Werner, John S.

    2010-02-01

    We describe results of retinal imaging with a novel instrument that combines adaptive optics - Fourier-domain optical coherence tomography (AO-OCT) with an adaptive optics scanning laser ophthalmoscope (AO-SLO). One of the benefits of combining Fd-OCT with SLO includes automatic co-registration between the two imaging modalities and the potential for correcting lateral and transversal eye motion resulting in motion artifact-free volumetric retinal imaging. Additionally this allows for direct comparison between retinal structures that can be imaged with both modalities (e.g., photoreceptor mosaics or microvasculature maps). This dual imaging modality could provide insight into some retinal properties that could not be accessed by a single imaging system. Additionally, extension of OCT and SLO beyond structural imaging may open new avenues for diagnostics and testing in ophthalmology. In particular, non-invasive vasculature mapping with these modalities holds promise of replacing fluorescein angiography in vascular identification. Several new improvements of our system are described, including results of testing a novel 97-actuator deformable mirror and AO-SLO light intensity modulation.

  16. Optical 3D-storage in sol-gel materials with a reading by Optical Coherence Tomography-technique

    CERN Document Server

    Reyes-Esqueda, J A; Lecaque, R; Ramaz, F; Forget, B C; Dubois, A; Briat, B; Boccara, C; Roger, G; Canva, M; Levy, Y; Chaput, F; Boilot, J P; Reyes-Esqueda, Jorge-Alejandro; Vabre, Laurent; Lecaque, Romain; Ramaz, Francois; Forget, Benoit C.; Dubois, Arnaud; Briat, Bernard; Boccara, Claude; Roger, Gisele; Canva, Michael; Levy, Yves; Chaput, Frederic; Boilot, Jean-Pierre

    2003-01-01

    We report on the recording of 3D optical memories in sol-gel materials by using a non-linear absorption effect. This effect induces a local change of the optical properties of the material which is read and quantified with a high resolution full-field Optical Coherence Tomography setup. It is the first time that this technique is used for this purpose. Data recording was performed by focused picosecond (ps) single-pulse irradiation at 1064 nm with energy densities of 10 and 33 J/cm2 per pulse.

  17. Optical 3D-storage in sol-gel materials with a reading by Optical Coherence Tomography-technique

    OpenAIRE

    Reyes-esqueda, Jorge-alejandro; Vabre, Laurent; Lecaque, Romain; Ramaz, Francois; Forget, Benoit C.; Dubois, Arnaud; Briat, Bernard; Boccara, Claude; Roger, Gisele; Canva, Michael; Levy, Yves; Chaput, Frederic; Boilot, Jean-pierre; ,

    2006-01-01

    We report on the recording of 3D optical memories in sol-gel materials by using a non-linear absorption effect. This effect induces a local change of the optical properties of the material which is read and quantified with a high resolution full-field Optical Coherence Tomography setup. It is the first time that this technique is used for this purpose. Data recording was performed by focused picosecond (ps) single-pulse irradiation at 1064 nm with energy densities of 10 and ...

  18. Comparison of the performance of two depth-resolved optical imaging systems: laminar optical tomography and spatially modulated imaging

    Science.gov (United States)

    Guevara, Edgar; Abran, Maxime; Bélanger, Samuel; Ouakli, Nicolas; Lesage, Frédéric

    2010-02-01

    The objective of this work is to compare quantitatively the imaging capabilities of a laminar optical tomography (LOT) system with those of a spatially modulated imaging (SMI) system. LOT is a three dimensional optical imaging technique that achieves depth sensitivity by measuring multiple-scattered light at different source-detector separations. The SMI method is based on spatially modulated illumination-detection patterns, which encode both optical properties and depth information. In this work, simulation studies are carried out at different noise levels, to obtain the figures of merit of tomographic reconstructions for both systems. Experiments on phantoms are performed to demonstrate the validity of the numerical results.

  19. In-situ monitoring of surface post-processing in large aperture fused silica optics with Optical Coherence Tomography

    Energy Technology Data Exchange (ETDEWEB)

    Guss, G M; Bass, I l; Hackel, R P; Mailhiot, C; Demos, S G

    2008-02-08

    Optical Coherence Tomography is explored as a method to image laser-damage sites located on the surface of large aperture fused silica optics during post-processing via CO{sub 2} laser ablation. The signal analysis for image acquisition was adapted to meet the sensitivity requirements for this application. A long-working distance geometry was employed to allow imaging through the opposite surface of the 5-cm thick optic. The experimental results demonstrate the potential of OCT for remote monitoring of transparent material processing applications.

  20. Multimodal photoacoustic and optical coherence tomography scanner using an all optical detection scheme for 3D morphological skin imaging

    OpenAIRE

    Zhang, Edward Z.; Povazay, Boris; Laufer, Jan; Alex, Aneesh; Hofer, Bernd; Pedley, Barbara; Glittenberg, Carl; Treeby, Bradley; Cox, Ben; Beard, Paul; Drexler, Wolfgang

    2011-01-01

    A noninvasive, multimodal photoacoustic and optical coherence tomography (PAT/OCT) scanner for three-dimensional in vivo (3D) skin imaging is described. The system employs an integrated, all optical detection scheme for both modalities in backward mode utilizing a shared 2D optical scanner with a field-of-view of ~13 × 13 mm2. The photoacoustic waves were detected using a Fabry Perot polymer film ultrasound sensor placed on the surface of the skin. The sensor is transparent in the spectral r...

  1. Ultrahigh-speed ultrahigh-resolution adaptive optics: optical coherence tomography system for in-vivo small animal retinal imaging

    Science.gov (United States)

    Jian, Yifan; Xu, Jing; Zawadzki, Robert J.; Sarunic, Marinko V.

    2013-03-01

    Small animal models of human retinal diseases are a critical component of vision research. In this report, we present an ultrahigh-resolution ultrahigh-speed adaptive optics optical coherence tomography (AO-OCT) system for small animal retinal imaging (mouse, fish, etc.). We adapted our imaging system to different types of small animals in accordance with the optical properties of their eyes. Results of AO-OCT images of small animal retinas acquired with AO correction are presented. Cellular structures including nerve fiber bundles, capillary networks and detailed double-cone photoreceptors are visualized.

  2. Measurement of tissue optical properties with optical coherence tomography: Implication for noninvasive blood glucose concentration monitoring

    Science.gov (United States)

    Larin, Kirill V.

    Approximately 14 million people in the USA and more than 140 million people worldwide suffer from diabetes mellitus. The current glucose sensing technique involves a finger puncture several times a day to obtain a droplet of blood for analysis. There have been enormous efforts by many scientific groups and companies to quantify glucose concentration noninvasively using different optical techniques. However, these techniques face limitations associated with low sensitivity, accuracy, and insufficient specificity of glucose concentrations over a physiological range. Optical coherence tomography (OCT), a new technology, is being applied for noninvasive imaging in tissues with high resolution. OCT utilizes sensitive detection of photons coherently scattered from tissue. The high resolution of this technique allows for exceptionally accurate measurement of tissue scattering from a specific layer of skin compared with other optical techniques and, therefore, may provide noninvasive and continuous monitoring of blood glucose concentration with high accuracy. In this dissertation work I experimentally and theoretically investigate feasibility of noninvasive, real-time, sensitive, and specific monitoring of blood glucose concentration using an OCT-based biosensor. The studies were performed in scattering media with stable optical properties (aqueous suspensions of polystyrene microspheres and milk), animals (New Zealand white rabbits and Yucatan micropigs), and normal subjects (during oral glucose tolerance tests). The results of these studies demonstrated: (1) capability of the OCT technique to detect changes in scattering coefficient with the accuracy of about 1.5%; (2) a sharp and linear decrease of the OCT signal slope in the dermis with the increase of blood glucose concentration; (3) the change in the OCT signal slope measured during bolus glucose injection experiments (characterized by a sharp increase of blood glucose concentration) is higher than that measured in the glucose clamping experiments (characterized by slow, controlled increase of the blood glucose concentration); and (4) the accuracy of glucose concentration monitoring may substantially be improved if optimal dimensions of the probed skin area are used. The results suggest that high-resolution OCT technique has a potential for noninvasive, accurate, and continuous glucose monitoring with high sensitivity.

  3. Tomography

    International Nuclear Information System (INIS)

    Tomography is a non-invasive technique now being developed as an industrial tool. It will be most useful for studying complex geometries where other NDT techniques provide ambiguous information, and complex processes where the quantitative data obtained can be used to rigorously test our understanding of the process. An overview of the CRNL program is presented

  4. Three-dimensional fluorescence tomography of human breast tissues in vivo using a hand-held optical imager

    OpenAIRE

    Erickson, Sarah J.; Martinez, Sergio L.; Decerce, Joseph; Romero, Adrian; Caldera, Lizeth; Godavarty, Anuradha

    2013-01-01

    Diffuse optical imaging using non-ionizing radiation is a non-invasive method that shows promise towards breast cancer diagnosis. Hand-held optical imagers show potential for clinical translation of the technology, yet they have not been used towards 3D tomography. Herein, 3D tomography of human breast tissue in vivo is demonstrated for the first time using a hand-held optical imager with automated coregistration facilities. Simulation studies are performed on breast geometries to demonstrate...

  5. Real-time diffuse optical tomography based on structured illumination

    Science.gov (United States)

    Bélanger, Samuel; Abran, Maxime; Intes, Xavier; Casanova, Christian; Lesage, Frédéric

    2010-01-01

    A new optical acquisition scheme based on a pair of digital micromirror devices is developed and applied to three-dimensional tomographic imaging of turbid media. By using pairs of illumination-detection patterns with a single detector, we were able to perform high-resolution quantitative volumetric imaging of absorption heterogeneities embedded in optically thick samples. Additionally, a tomographic reconstruction algorithm was implemented on a graphical processor unit to provide optical reconstructions at a frame rate of 2 Hz. The structured illumination method proposed in this work has significant cost advantages over camera systems, as only a single detector is required. This configuration also has the potential to increase frame rate.

  6. A soft deformable tissue-equivalent phantom for diffuse optical tomography

    International Nuclear Information System (INIS)

    A recipe is presented for the manufacture of highly compressible phantoms for diffuse optical tomography. The recipe is based on polyvinyl alcohol (PVA) slime, a viscoelastic fluid which readily deforms under moderate pressure. Scattering particles and absorbing compounds can be added to provide a uniform material with stable and reproducible optical properties. A linear relationship between the concentration of scattering particles (either titanium dioxide or microspheres) and the transport scatter coefficient is demonstrated. Phantoms of an arbitrary size and shape may be produced by containing the slime within a thin latex shell, and a stability over a period of at least 3 months has been established. The deformable phantoms may be used to test and calibrate optical tomography systems designed for use on patients with irregular or variable geometries

  7. A soft deformable tissue-equivalent phantom for diffuse optical tomography

    Science.gov (United States)

    Hebden, Jeremy C.; Price, Ben D.; Gibson, Adam P.; Royle, Gary

    2006-11-01

    A recipe is presented for the manufacture of highly compressible phantoms for diffuse optical tomography. The recipe is based on polyvinyl alcohol (PVA) slime, a viscoelastic fluid which readily deforms under moderate pressure. Scattering particles and absorbing compounds can be added to provide a uniform material with stable and reproducible optical properties. A linear relationship between the concentration of scattering particles (either titanium dioxide or microspheres) and the transport scatter coefficient is demonstrated. Phantoms of an arbitrary size and shape may be produced by containing the slime within a thin latex shell, and a stability over a period of at least 3 months has been established. The deformable phantoms may be used to test and calibrate optical tomography systems designed for use on patients with irregular or variable geometries.

  8. Time-series estimation of biological factors in optical diffusion tomography

    International Nuclear Information System (INIS)

    We apply state space estimation techniques to the time-varying reconstruction problem in optical tomography. We develop a stochastic model for describing the evolution of quasi-sinusoidal medical signals such as the heartbeat, assuming these are represented as a known frequency with randomly varying amplitude and phase. We use the extended Kalman filter in combination with spatial regularization techniques to reconstruct images from highly under-determined time-series data. This system also naturally segments activity belonging to different biological processes. We present reconstructions of simulated data and of real data recorded from the human motor cortex (Franceschini et al 2000 Optics Express 6 49-57). It is argued that the application of these time-series techniques improves both the fidelity and temporal resolution of reconstruction in optical tomography

  9. Simultaneous reconstruction of internal tissue region boundaries and coefficients in optical diffusion tomography

    International Nuclear Information System (INIS)

    In this paper we propose a new numerical method to the inverse problem in optical diffusion tomography. We consider the reconstruction of the diffusion and absorption coefficients (?, ?a) within a domain ? which is known to consist of a set of disjoint regions of distinct tissue types. The assumption is that the regions of different tissues are bounded by smooth boundary curves and have constant absorption and diffusion coefficients. The goal in the proposed method is to reconstruct simultaneously the boundaries of the tissue regions together with the absorption and diffusion coefficients within these regions. The solution of the problem is based on the finite element method and subdivision of the elements. The performance of the proposed method is evaluated by simulations in which the optical parameters (?, ?a) are relevant in medical applications of optical tomography. It is shown that the proposed method is able to recover both the boundaries and the coefficients with good accuracy. (author)

  10. Test target for characterizing 3D resolution of optical coherence tomography

    Science.gov (United States)

    Hu, Zhixiong; Hao, Bingtao; Liu, Wenli; Hong, Baoyu; Li, Jiao

    2014-12-01

    Optical coherence tomography (OCT) is a non-invasive 3D imaging technology which has been applied or investigated in many diagnostic fields including ophthalmology, dermatology, dentistry, cardiovasology, endoscopy, brain imaging and so on. Optical resolution is an important characteristic that can describe the quality and utility of an image acquiring system. We employ 3D printing technology to design and fabricate a test target for characterizing 3D resolution of optical coherence tomography. The test target which mimics USAF 1951 test chart was produced with photopolymer. By measuring the 3D test target, axial resolution as well as lateral resolution of a spectral domain OCT system was evaluated. For comparison, conventional microscope and surface profiler were employed to characterize the 3D test targets. The results demonstrate that the 3D resolution test targets have the potential of qualitatively and quantitatively validating the performance of OCT systems.

  11. Analysis and optimization of a diffuse photon optical tomography of turbid media

    International Nuclear Information System (INIS)

    In a numerical study, we investigate a diffuse-photon computed tomography of a turbid medium. Using a perturbation approach, we relate through a matrix K a bulk heterogeneous distribution of the optical absorption coefficient ?a that characterizes the heterogeneity in an otherwise homogeneous turbid medium to the diffuse photon flux that emerges from its surface. By studying the condition number (NC) of the matrix K as a function of illumination-detection schemes and choices of reconstruction grids, we explore strategies that optimize the fidelity and spatial resolution of the computed tomography. (c) 2000 The American Physical Society

  12. Contrast enhancement using Mie spectra representation for spectroscopic optical coherence tomography

    Science.gov (United States)

    Seck, Hon Luen; Zhang, Ying; Soh, Yeng Chai

    2015-03-01

    The paper presents a spectroscopic optical coherence tomography (SOCT) method that offers a tomography imaging contrast in scatterer size. In the method, the depth resolved spectroscopy is modelled as a linear combination of basis spectra from scatterers in a prescribed dictionary. The depth resolved spectroscopy is first reconstructed by searching the optimal expansion of the SOCT spectral measurement over the basis spectra. Then the scatterer sizes corresponding to the spectra in the optimal expansion are used to display the SOCT image. Simulation and experimental studies demonstrated that the proposed contrast can differentiate the scatterer clusters in samples.

  13. Nanoscale zoom tomography with hard x rays using Kirkpatrick-Baez optics

    International Nuclear Information System (INIS)

    To overcome the limitations in terms of spatial resolution and field of view of existing tomography techniques, a hard x-ray projection microscope is realized based on the sub-100-nm focus produced by Kirkpatrick-Baez optics. The sample is set at a small distance downstream of the focus and Fresnel diffraction patterns with variable magnification are recorded on a medium-resolution detector. While the approach requires a specific phase retrieval procedure and correction for mirror imperfections, it allows zooming nondestructively into bulky samples. Quantitative three-dimensional nanoscale microscopy is demonstrated on an aluminum alloy in local tomography mode

  14. Spectral hole burning for ultrasound-modulated optical tomography of thick tissue

    OpenAIRE

    Xu, Xiao; Kothapalli, Sri-rajasekhar; Liu, Honglin; Wang, Lihong V.

    2010-01-01

    We apply spectral hole burning (SHB)-aided detection in ultrasound-modulated optical tomography (UOT) to image optical heterogeneities in thick tissue-mimicking phantom samples and chicken breast tissue. The efficiency of SHB is improved by using a Tm3+:YAG crystal of higher doping concentration (2.0-atomic%) and a double-pass pumping configuration, in which the pump beam is transmitted through the crystal twice to burn a deeper spectral hole with the available optical intensity. With the imp...

  15. Tomography

    International Nuclear Information System (INIS)

    Tomography is a non-intrusive imaging technique being developed at CRNL as an industrial tool for generating quantitative cross-sectional density maps of objects. Of most interest is tomography's ability to: distinguish features within complex geometries where other NDT techniques fail because of the complexity of the geometry; detect/locate small density changes/defects within objects, e.g. void fraction measurements within thick-walled vessels, shrink cavities in castings, etc.; provide quantitative data that can be used in analyses, e.g. of complex processes, or fracture mechanics; and provide objective quantitative data that can be used for (computer-based) quality assurance decisions, thereby reducing and in some cases eliminating the present subjectivity often encountered in NDT. The CRNL program is reviewed and examples are presented to illustrate the potential and the limitations of the technology

  16. Optical detection of indocyanine green encapsulated biocompatible poly (lactic-co-glycolic) acid nanoparticles with photothermal optical coherence tomography

    OpenAIRE

    Subhash, Hrebesh M.; Xie, Hui; Smith, Jeffrey W.; Mccarty, Owen J. T.

    2012-01-01

    We describe a functional imaging paradigm that uses photothermal optical coherence tomography (PT-OCT) to detect indocyanine green (ICG)-encapsulated biocompatible poly(lactic-co-glycolic) acid (PLGA) nanoparticles embedded in highly scattering tissue phantoms with high resolution and sensitivity. The ICG-loaded PLGA nanoparticles were fabricated using a modified emulsification solvent diffusion method. With a 20 kHz axial scan rate, PT-OCT based on spectral-domain interferometric configurati...

  17. Hand scanning optical coherence tomography imaging using encoder feedback.

    Science.gov (United States)

    Iftimia, Nicusor; Maguluri, Gopi; Chang, Ernest W; Chang, Shing; Magill, John; Brugge, William

    2014-12-15

    We present a new method for generating micron-scale OCT images of interstitial tissue with a hand scanning probe and a linear optical encoder that senses probe movement relative to a fixed reference point, i.e., tissue surface. Based on this approach, we demonstrate high resolution optical imaging of biological tissues through a very long biopsy needle. Minor artifacts caused by tissue noncompliance are corrected using a software algorithm which detects the simple repetition of the adjacent A-scans. This hand-scanning OCT imaging approach offers the physician the freedom to access imaging sites of interest repeatedly. PMID:25503002

  18. Small animal optical diffusion tomography with targeted fluorescence.

    Science.gov (United States)

    Gaind, Vaibhav; Tsai, Hsiao-Rho; Webb, Kevin J; Chelvam, Venkatesh; Low, Philip S

    2013-06-01

    Despite the broad impact in medicine that optics can bring, thus far practical approaches are limited to weak scatter or near-surface monitoring. We show a method that utilizes a laser topography scan and a diffusion equation model to describe the photon transport, together with a multiresolution unstructured grid solution to the nonlinear optimization measurement functional, that overcomes these limitations. We conclude that it is possible to achieve whole body optical imaging with a resolution suitable for finding cancer nodules within an organ during surgery, with the aid of a targeted imaging agent. PMID:24323101

  19. In vivo imaging of zebrafish from embryo to adult stage with optical projection tomography

    Science.gov (United States)

    Bassi, Andrea; Fieramonti, Luca; D'Andrea, Cosimo; Valentini, Gianluca; Cubeddu, Rinaldo; De Silvestri, Sandro; Cerullo, Giulio; Foglia, Efrem; Cotelli, Franco

    2013-02-01

    Optical Projection Tomography (OPT) is a three dimensional imaging technique that is particularly suitable for studying millimeter sized biological samples and organisms. Similarly to x-ray computed tomography, OPT is based on the acquisition of a sequence of images taken through the sample at many angles (projections). Assuming the linearity of the optical absorption process, the projections are combined to reconstruct the 3-D volume of the sample, typically using a filtered back-projection algorithm. OPT has been applied to in-vivo imaging of zebrafish (Danio rerio). The instrument and the protocol for in vivo imaging of zebrafish embryos and juvenile specimens are described. Light scattering remains a challenge for in vivo OPT, especially when samples at the upper size limit, like zebrafish at the adult stage, are under study. We describe Time-Gated Optical Projection Tomography (TGOPT), a technique able to reconstruct adult zebrafish internal structures by counteracting the scattering effects through a fast time-gate. The time gating mechanism is based on non-linear optical upconversion of an infrared ultrashort laser pulse and allows the detection of quasi-ballistic photons within a 100 fs temporal gate. This results in a strong improvement in contrast and resolution with respect to conventional OPT. Artifacts in the reconstructed images are reduced as well. We show that TGOPT is suited for imaging the skeletal system and nervous structures of adult zebrafish.

  20. High-speed volumetric imaging of cone photoreceptors with adaptive optics spectral-domain optical coherence tomography

    OpenAIRE

    Zhang, Yan; Cense, Barry; Rha, Jungtae; Jonnal, Ravi S.; Gao, Weihua; Zawadzki, Robert J.; Werner, John S.; Jones, Steve; Olivier, Scot; Miller, Donald T.

    2006-01-01

    We report the first observations of the three-dimensional morphology of cone photoreceptors in the living human retina. Images were acquired with a high-speed adaptive optics (AO) spectral-domain optical coherence tomography (SD-OCT) camera. The AO system consisted of a Shack-Hartmann wavefront sensor and bimorph mirror (AOptix) that measured and corrected the ocular and system aberrations at a closed-loop rate of 12 Hz. The bimorph mirror was positioned between the XY mechanical scanners and...

  1. Full range spectral domain optical coherence tomography using a fiber-optic probe as a self-phase shifter.

    Science.gov (United States)

    Min, Eun Jung; Shin, Jun Geun; Lee, Jae Hwi; Yasuno, Yoshiaki; Lee, Byeong Ha

    2012-08-01

    We present a full range handheld probe type spectral domain optical coherence tomography (SD-OCT) method. Here, the sample arm is composed of a tilted fiber-optic cantilever scanner; thus, the phase shift concurrently occurs while sample scanning. With the phase shift, we could achieve a full range complex-conjugate-free OCT image with no additional phase shifters in the reference arm. To realize this technique, a magnetically actuated probe was adopted. Full range SD-OCT images of a pearl, human fingernail, and human tooth were subsequently obtained using this suggested probe. The scanning range and acquisition speed were 3 mm and 20 frames/s, respectively. PMID:22859100

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

    International Nuclear Information System (INIS)

    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 3600 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 roval 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 dB on severe noise-affected reconstructions revealing original-noise-hidden-image details. These results show the utility of the BM3D approach for OPT under typical conditions of very low light absorption, suggesting its implementation as an efficient alternative to other filtering schemes such as for example the median filter.

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

    Energy Technology Data Exchange (ETDEWEB)

    Fumene Feruglio, P; Vinegoni, C; Weissleder, R [Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School, 185 Cambridge Street, Boston, MA 02114 (United States); Gros, J [Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston MA 02115 (United States); Sbarbati, A, E-mail: cvinegoni@mgh.harvard.ed [Department of Morphological and Biomedical Sciences, University of Verona, Strada Le Grazie 8, 37134 Verona (Italy)

    2010-09-21

    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{sup 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 dB on severe noise-affected reconstructions revealing original-noise-hidden-image details. These results show the utility of the BM3D approach for OPT under typical conditions of very low light absorption, suggesting its implementation as an efficient alternative to other filtering schemes such as for example the median filter.

  4. First steps toward 3D high resolution imaging using adaptive optics and full-field optical coherence tomography

    Science.gov (United States)

    Blanco, Leonardo; Blavier, Marie; Glanc, Marie; Pouplard, Florence; Tick, Sarah; Maksimovic, Ivan; Chenegros, Guillaume; Mugnier, Laurent; Lacombe, Francois; Rousset, Gérard; Paques, Michel; Le Gargasson, Jean-François; Sahel, Jose-Alain

    2008-09-01

    We describe here two parts of our future 3D fundus camera coupling Adaptive Optics and full-field Optical Coherence Tomography. The first part is an Adaptive Optics flood imager installed at the Quinze-Vingts Hospital, regularly used on healthy and pathological eyes. A posteriori image reconstruction is performed, increasing the final image quality and field of view. The instrument lateral resolution is better than 2 microns. The second part is a full-field Optical Coherence Tomograph, which has demonstrated capability of performing a simple kind of "4 phases" image reconstruction of non biological samples and ex situ retinas. Final aim is to couple both parts in order to achieve 3D high resolution mapping of in vivo retinas.

  5. Optical design of an optical coherence tomography and multispectral fluorescence imaging endoscope to detect early stage ovarian cancer

    Science.gov (United States)

    Tate, Tyler; Keenan, Molly; Swan, Elizabeth; Black, John; Utzinger, Urs; Barton, Jennifer

    2014-12-01

    The five year survival rate for ovarian cancer is over 90% if early detection occurs, yet no effective early screening method exists. We have designed and are constructing a dual modality Optical Coherence Tomography (OCT) and Multispectral Fluorescence Imaging (MFI) endoscope to optically screen the Fallopian tube and ovary for early stage cancer. The endoscope reaches the ovary via the natural pathway of the vagina, cervix, uterus and Fallopian tube. In order to navigate the Fallopian tube the endoscope must have an outer diameter of 600 ?m, be highly flexible, steerable, tracking and nonperforating. The imaging systems consists of six optical subsystems, two from OCT and four from MFI. The optical subsystems have independent and interrelated design criteria. The endoscope will be tested on realistic tissue models and ex vivo tissue to prove feasibility of future human trials. Ultimately the project aims to provide women the first effective ovarian cancer screening technique.

  6. Sensing Plasmon-Resonant Nanorods in Tissue with Optical Coherence Tomography

    Science.gov (United States)

    Oldenburg, Amy

    2009-11-01

    Gold nanoparticles (GNPs) are of high interest for biomedical imaging and photothermal therapy due to their plasmon-resonant nature. However, their utility is limited by transport and targeting to the disease of interest after administration in the living body. Optical coherence tomography can image the distribution of GNPs on the micro- to meso-scale, leading toward a better understanding of these limiting factors. Plasmon-resonant nanorods provide strong optical absorption at near-infrared wavelengths, and are studied using an optical coherence tomography system based on a broadband laser centered at 800nm. The ability to sense GNPs against a biological tissue background is treated as a sensing problem with parameters including the nanorod volume and aspect ratio, optical detection metrics including extinction, a new backscattering albedo metric based on the ratio of backscattering to extinction, and spectroscopic analysis. A key element of this analysis is determining the native tissue optical response, optical signal noise, and spatial heterogeneity before addition of the GNPs. Experiments are performed in skin-like tissue phantoms where a sensitivity of 30ppm is found. Experiments in excised human mammary tumors reveal additional challenges for imaging in real tissues, and the results of various processing techniques are compared.

  7. Retinal blood flow measurement by using optical coherence tomography

    Science.gov (United States)

    Makita, Shuichi; Fabritius, Tapio; Miura, Masahiro; Yatagai, Toyohiko; Yasuno, Yoshiaki

    2008-02-01

    Quantification of the three-dimensional (3D) retinal vessel structure and blood flow is demonstrated. 3D blood flow distribution is obtained by Doppler optical coherence angiography (D-OCA). Vessel parameters, i.e. diameter, orientation, and position, are determined in an en face vessel image. The Doppler angle is estimated as the angle between the retinal vessel and the incident probing beam in representative cross-sectional flow image which extracted from the 3D flow distribution according to the vessel parameters. Blood flow velocity and volume rate can be quantified with these vessel parameters. The retinal blood flow velocity and volume rate are measured in the retinal vessels around the optic nerve head.

  8. Laser Tomography Adaptive Optics (LTAO): A performance study

    CERN Document Server

    Tatulli, E

    2013-01-01

    We present an analytical derivation of the on-axis performance of Adaptive Optics systems using a given number of guide stars of arbitrary altitude, distributed at arbitrary angular positions in the sky. The expressions of the residual error are given for cases of both continuous and discrete turbulent atmospheric profiles. Assuming Shack-Hartmann wavefront sensing with circular apertures, we demonstrate that the error is formally described by integrals of products of three Bessel functions. We compare the performance of Adaptive Optics correction when using natural, Sodium or Rayleigh laser guide stars. For small diameter class telescopes (~5m), we show that a few number of Rayleigh beacons can provide similar performance to that of a single Sodium laser, for a lower overall cost of the instrument. For bigger apertures, using Rayleigh stars may not be such a suitable alternative because of the too severe cone effect that drastically degrades the quality of the correction.

  9. Optical tomography: Development of a new medical imaging modality

    International Nuclear Information System (INIS)

    The demonstrated success of near-infrared spectroscopy as a diagnostic tool in medicine has encouraged physicists to pursue the development of an imaging technique based on the transmittance of optical wavelengths through tissue. Potential clinical applications include a means of detecting breast disease, and a cerebral imaging modality for mapping oxygenation and haemodynamics in the brain of newborn infants. Imaging of tissues with light is severely restricted by the overwhelming scatter which occurs when optical radiation propagates through tissue. However, recent innovations in technology and the development of new tomographic reconstruction procedures suggest that a clinically viable imaging modality is achievable. In this paper the recent progress in this field of research is reviewed, and the prospects for ultimate success are discussed

  10. 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. PMID:25295908

  11. Correction of image artifacts caused by refractive index gradients in scanning laser optical tomography

    Science.gov (United States)

    Antonopoulos, Georgios Christian; Pscheniza, Dimitri; Lorbeer, Raoul-Amadeus; Heidrich, Marko; Schwanke, Kristin; Zweigerdt, Robert; Ripken, Tammo; Meyer, Heiko

    2014-03-01

    We present a technique for correcting image artifacts caused by refractive index distributions in Scanning Laser Optical Tomography (SLOT) and Optical Projection Tomography (OPT). Projection images can be distorted due to the presence of a refractive index distribution around the sample. We consider the special case of a refractive index distribution given by a capillary around a sample. The particular application we are interested in is in vitro imaging of cell spheroids in a glass capillary. Numerical simulations and experimental results are used to illustrate the connection between the Radon transform and the refracted projection. Thereupon we will describe a technique that transforms refracted projections to parallel ray Radon projections and thus allows artifact free reconstruction within the sample volume.

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

    International Nuclear Information System (INIS)

    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

  13. Macular edema in the era of spectral-domain optical coherence tomography

    Directory of Open Access Journals (Sweden)

    Hunter A

    2013-10-01

    Full Text Available Allan Hunter,1 Eric K Chin,1 David G Telander,21Department of Ophthalmology, University of California, Davis, 2Department of Ophthalmology, Retinal Consultants, Sacramento, CA, USAAbstract: The development of spectral-domain optical coherence tomography (OCT allows for the highest commercially available resolution of in vivo retinal anatomic details to date. The ability to see the macula with ever increasing detail is dramatically improving our understanding of the pathogenesis of retinal disease. However, the only prospective study that partially evaluated spectral-domain OCT versus time-domain OCT failed to show any clinical benefit of increased OCT resolution. Clinical outcomes, eg, best-corrected visual acuity, central macular thickness and number of injections, with “newer” OCT technologies remain an unproven advantage.Keywords: retina, macular edema, optical coherence tomography, fluorescein angiography, indocyanine green angiography

  14. High resolution 3D image reconstruction in laminar optical tomography based on compressive sensing

    Science.gov (United States)

    Yang, Fugang; Ozturk, Mehmet S.; Cong, Wenxiang; Wang, Ge; Intes, Xavier

    2014-02-01

    Laminar optical tomography (LOT) combines the advantages of diffuse optical tomography image reconstruction and a microscopy-based setup to allow non-contact imaging at depth up to a few millimeters. However, LOT image reconstruction paradigm is inherently an ill-posed and computationally expensive inverse problem. Herein, we cast the LOT inverse problem in the compressive sensing (CS) framework to exploit the sparsity of the fluorophore yield in the image domain and to address the ill-posedness of the LOT inverse problem. We apply this new approach to thick tissue engineering applications. We demonstrate the enhanced resolution of our method in 3-D numerical simulations of anatomically accurate microvasculature and using real data obtained from phantom experiments. Furthermore, CS is shown to be more robust against the reduction of measurements in comparison to the classic methods for such application. Potential benefits and shortcomings of the CS approach in the context of LOT are discussed.

  15. A haemodynamic response function model in spatio-temporal diffuse optical tomography

    International Nuclear Information System (INIS)

    Diffuse optical tomography (DOT) is a new and effective technique for functional brain imaging. It can detect local changes in both oxygenated and deoxygenated haemoglobin concentrations in tissue based on differential absorption at multiple wavelengths. Traditional methods in spatio-temporal analysis of haemoglobin concentrations in diffuse optical tomography first reconstruct the spatial distribution at different time instants independently, then look at the temporal dynamics on each pixel, without incorporating any temporal information as a prior in the image reconstruction. In this work, we present a temporal haemodynamic response function model described by a basis function expansion, in a joint spatio-temporal DOT reconstruction of haemoglobin concentration changes during simulated brain activation. In this joint framework, we simultaneously employ spatial regularization, spectral information and temporal assumptions. We also present an efficient algorithm for solving the associated large-scale systems. The expected improvements in spatial resolution and contrast-to-noise ratio are illustrated with simulations of human brain activation

  16. Phase-contrast diffuse optical tomography for in vivo breast imaging: a two-step method

    International Nuclear Information System (INIS)

    We present a two-step reconstruction method that can qualitatively and quantitatively improve the reconstruction of tissue refractive index (RI) distribution by phase-contrast diffuse optical tomography (PCDOT). In this two-step method, we first recover the distribution of tissue absorption and scattering coefficients by conventional diffuse optical tomography to obtain the geometrical information of lesions, allowing the incorporation of geometrical information as a priori in the PCDOT reconstruction using a locally refined mesh. The method is validated by a series of phantom experiments and evaluated using in vivo data from 42 human subjects. The results demonstrate clear contrast of RI between the lesion and the surroundings, making the image interpretation straightforward. The sensitivity and specificity from these 42 cases are both 81% when RI is used as an imaging parameter for distinguishing between malignant and benign lesions.

  17. Image reconstruction for diffuse optical tomography based on radiative transfer equation.

    Science.gov (United States)

    Bi, Bo; Han, Bo; Han, Weimin; Tang, Jinping; Li, Li

    2015-01-01

    Diffuse optical tomography is a novel molecular imaging technology for small animal studies. Most known reconstruction methods use the diffusion equation (DA) as forward model, although the validation of DA breaks down in certain situations. In this work, we use the radiative transfer equation as forward model which provides an accurate description of the light propagation within biological media and investigate the potential of sparsity constraints in solving the diffuse optical tomography inverse problem. The feasibility of the sparsity reconstruction approach is evaluated by boundary angular-averaged measurement data and internal angular-averaged measurement data. Simulation results demonstrate that in most of the test cases the reconstructions with sparsity regularization are both qualitatively and quantitatively more reliable than those with standard L? regularization. Results also show the competitive performance of the split Bregman algorithm for the DOT image reconstruction with sparsity regularization compared with other existing L? algorithms. PMID:25648064

  18. Image Reconstruction for Diffuse Optical Tomography Based on Radiative Transfer Equation

    Science.gov (United States)

    Han, Bo; Tang, Jinping

    2015-01-01

    Diffuse optical tomography is a novel molecular imaging technology for small animal studies. Most known reconstruction methods use the diffusion equation (DA) as forward model, although the validation of DA breaks down in certain situations. In this work, we use the radiative transfer equation as forward model which provides an accurate description of the light propagation within biological media and investigate the potential of sparsity constraints in solving the diffuse optical tomography inverse problem. The feasibility of the sparsity reconstruction approach is evaluated by boundary angular-averaged measurement data and internal angular-averaged measurement data. Simulation results demonstrate that in most of the test cases the reconstructions with sparsity regularization are both qualitatively and quantitatively more reliable than those with standard L2 regularization. Results also show the competitive performance of the split Bregman algorithm for the DOT image reconstruction with sparsity regularization compared with other existing L1 algorithms. PMID:25648064

  19. Depth resolved detection of lipid using spectroscopic optical coherence tomography

    OpenAIRE

    Fleming, Christine P.; Eckert, Jocelyn; Halpern, Elkan F.; Gardecki, Joseph A.; Tearney, Guillermo J.

    2013-01-01

    Optical frequency domain imaging (OFDI) can identify key components related to plaque vulnerability but can suffer from artifacts that could prevent accurate identification of lipid rich regions. In this paper, we present a model of depth resolved spectral analysis of OFDI data for improved detection of lipid. A quadratic Discriminant analysis model was developed based on phantom compositions known chemical mixtures and applied to a tissue phantom of a lipid-rich plaque. We demonstrate that a...

  20. Automatic Detection of Glaucoma Using Optical Coherence Tomography Image

    OpenAIRE

    Rengaraj Venkatesh; Shenbaga Devi, S.; Ganesh Babu, T. R.

    2012-01-01

    Glaucoma is an eye disorder in which the optic nerve suffers damage, leading to vision defect in the affected eye(s) and rolling to complete blindness if untreated. It is frequently associated with increased pressure in the fluid of the eye; aqueous humour. Glaucoma often goes undetected until significant damage to the subject’s visual field has occurred. As glaucoma progresses, neural tissues die, the nerve fiber layer thins and the cup-to-disk ratio increases. The conventional techn...

  1. Image reconstruction for optical tomography using photon density waves

    International Nuclear Information System (INIS)

    Diagnostic imaging makes use of different kinds of radiation. A recent type of imaging using near-infrared light is thought to be a safer and less-expensive method of in-vivo imaging. Near infra-red light can penetrate biological tissue to certain depths. The problem of using near infrared light for imaging, is that the scattering of the photons dominates absorption, causing difficulties in the reconstruction model on which biomedical optical imaging depends crucially. The aim of this thesis is to develop and investigate the performance of a reconstruction algorithm in the frequency domain which allows fast and efficient reconstruction of the image of a limb, or an optical phantom. The forward problem of the propagation of photons inside biological tissue is modelled using the Diffusion Approximation theory solved by the finite element method. Values of DC intensity, phase shift and modulation depth at the boundary as functions of the diffusion and absorption coefficients are given. The inverse model is formulated as a nonlinear least-squares optimisation problem. The Truncated Newton method with Trust region is used to determine the optical properties. Reverse differentiation is used to calculate the error function because of its speed advantage over forward differentiation. A sensitivity analysis is performed to investigate the simultaneous reconstruction of the diffusion and absorption coefficients. The use of a combined error function of DC intensity, phase and moror function of DC intensity, phase and modulation prove to be the most successful at recovering the optical parameters. The ability to distinguish between object size and size of optical parameter is also investigated. Contrast, mean and standard deviation are used as measures of the performance of the reconstruction algorithm. A Tikhonov regularisation method was used to improve ill-conditioning and behaviour in the presence of noise. An investigation of the optimal regularisation parameter is undertaken with the addition of noise to the measured data. Use of the L-curve method is investigated. This work has resulted in an efficient and functional reconstruction algorithm and program for the image reconstruction in the frequency domain. (author)

  2. Reproducibility of qualitative assessment of stent struts coverage by optical coherence tomography

    OpenAIRE

    Brugaletta, Salvatore; Garcia-garcia, Hector M.; Gomez-lara, Josep; Radu, Maria D.; Pawar, Ravindra; Khachabi, Jamal; Bruining, Nico; Sabate?, Manel; Serruys, Patrick W.

    2012-01-01

    Assessment of stent strut coverage by optical coherence tomography (OCT) is not standardized. The methodology most commonly used is based on a visual binary qualitative assessment (strut covered or not). However, the influence of magnification (zoom setting) to the inter- and intra-observer agreements has not yet been evaluated. Aim of our study was therefore to evaluate the agreements of this approach, taking into account various zoom settings. 126 struts from 10 selected frames were indepen...

  3. Miniature integrated optical coherence tomography (OCT) - ultrasound (US) probe for intravascular imaging

    Science.gov (United States)

    Li, Jiawen; Yin, Jiechen; Li, Xiang; Jing, Joe; Mukai, David; Mahon, Sari; Edris, Ahmad; Hoang, Khiet; Shung, K. Kirk; Brenner, Matthew; Narula, Jagat; Zhou, Qifa; Patel, Pranav; Chen, Zhongping

    2012-02-01

    A miniature integrated optical coherence tomography (OCT) - ultrasound (US) probing system for real-time intravascular imaging has been developed. The outer diameter of the integrated probe is 0.69 mm, which is small enough for imaging in human coronary arteries. This probe, which has high resolution and deep tissue penetration, is designed to identify vulnerable atherosclerotic plaques in coronary arteries. The first in vivo images of a rabbit abdominal aorta obtained by the integrated OCT-US probe are presented.

  4. Atherosclerotic tissue characterization in vivo by optical coherence tomography attenuation imaging

    OpenAIRE

    Tearney, Guillermo J.; Bouma, Brett E.; Oosterhuis, J. Wolter; Okamura, Takayuki; Noorden, Sander; Gonzalo, Nieves; Leenders, Geert L. J. H.; Koljenovic?, Senada; Steen, Anton F. W.; Serruys, Patrick W.; Regar, Evelyn; Goderie, Thade?; Soest, Gijs

    2009-01-01

    Optical coherence tomography (OCT) is rapidly becoming the method of choice for assessing arterial wall pathology in vivo. Atherosclerotic plaques can be diagnosed with high accuracy, including measurement of the thickness of fibrous caps, enabling an assessment of the risk of rupture. While the OCT image presents morphological information in highly resolved detail, it relies on interpretation of the images by trained readers for the identification of vessel wall components and tissue type. ...

  5. Spectral triangulation molecular contrast optical coherence tomography with indocyanine green as the contrast agent

    OpenAIRE

    Yang, Changhuei; Mcguckin, Laura E. L.; Simon, John D.; Choma, Michael A.; Applegate, Brian E.; Izatt, Joseph A.

    2004-01-01

    We report a new molecular contrast optical coherence tomography (MCOCT) implementation that profiles the contrast agent distribution in a sample by measuring the agent’s spectral differential absorption. The method, spectra triangulation MCOCT, can effectively suppress contributions from spectrally dependent scatterings from the sample without a priori knowledge of the scattering properties. We demonstrate molecular imaging with this new MCOCT modality by mapping the distribution of indocya...

  6. Refractive index measurement of acute rat brain tissue slices using optical coherence tomography

    OpenAIRE

    Sun, Jingjing; Lee, Sung Jin; Wu, Lei; Sarntinoranont, Malisa; Xie, Huikai

    2012-01-01

    An optical coherence tomography (OCT) system employing a microelectromechanical system (MEMS) mirror was used to measure the refractive index (RI) of anatomically different regions in acute brain tissue slices, in which viability was maintained. RI was measured in white-matter and grey-matter regions, including the cerebral cortex, putamen, hippocampus, thalamus and corpus callosum. The RI in the corpus callosum was found to be ~4% higher than the RIs in other regions. Changes in RI with tiss...

  7. Precise measurement of volume of eccrine sweat gland in mental sweating by optical coherence tomography

    Science.gov (United States)

    Sugawa, Yoshihiko; Fukuda, Akihiro; Ohmi, Masato

    2015-03-01

    We have demonstrated dynamic analysis of the physiological function of eccrine sweat glands underneath skin surface by optical coherence tomography (OCT). In this paper, we propose a method for extraction of the specific eccrine sweat gland by means of the connected component extraction process and the adaptive threshold method, where the en face OCT images are constructed by the swept-source OCT. In the experiment, we demonstrate precise measurement of the volume of the sweat gland in response to the external stimulus.

  8. In vivo imaging of nanoparticle delivery and tumor microvasculature with multimodal optical coherence tomography

    OpenAIRE

    Tucker-schwartz, Jason M.; Beavers, Kelsey R.; Sit, Wesley W.; Shah, Amy T.; Duvall, Craig L.; Skala, Melissa C.

    2014-01-01

    Current imaging techniques capable of tracking nanoparticles in vivo supply either a large field of view or cellular resolution, but not both. Here, we demonstrate a multimodality imaging platform of optical coherence tomography (OCT) techniques for high resolution, wide field of view in vivo imaging of nanoparticles. This platform includes the first in vivo images of nanoparticle pharmacokinetics acquired with photothermal OCT (PTOCT), along with overlaying images of microvascular and tissue...

  9. Measurement of Photoreceptor Layer in Glaucoma: A Spectral-Domain Optical Coherence Tomography Study

    OpenAIRE

    Ning Fan; Nina Huang; Dennis Shun Chiu Lam; Christopher Kai-shun Leung

    2011-01-01

    Objective. To measure and compare photoreceptor layer thickness between normal and glaucomatous eyes using spectral-domain optical coherence tomography (OCT). Methods. Thirty-eight healthy normal volunteers and 47 glaucoma patients were included in the analysis. One eye from each participant was randomly selected for macula imaging by a spectral-domain OCT (3D OCT-1000, Topcon, Tokyo, Japan). The foveal and parafoveal (1.5?mm from the fovea) outer nuclear layer (ONL) and inner and outer...

  10. Comparison of Spectral/Fourier Domain Optical Coherence Tomography Instruments for Assessment of Normal Macular Thickness

    OpenAIRE

    Sull, Alan C.; Vuong, Laurel N.; Price, Lori Lyn; Srinivasan, Vivek J.; Gorczynska, Iwona; Fujimoto, James G.; Schuman, Joel S.; Duker, Jay S.

    2010-01-01

    Purpose: The purpose of this study was to report normal macular thickness measurements and assess reproducibility of retinal thickness measurements acquired by a time-domain optical coherence tomography (OCT) (Stratus, Carl Zeiss Meditec, Inc., Dublin, CA) and three commercially available spectral/Fourier domain OCT instruments (Cirrus HD-OCT, Carl Zeiss Meditec, Inc.; RTVue-100, Optovue, Inc., Fremont, CA; 3D OCT-1000, Topcon, Inc., Paramus, NJ). Methods: Forty randomly selected eyes of ...

  11. Motion correction for phase-resolved dynamic optical coherence tomography imaging of rodent cerebral cortex

    OpenAIRE

    Lee, Jonghwan; Srinivasan, Vivek; Radhakrishnan, Harsha; Boas, David A.

    2011-01-01

    Cardiac and respiratory motions in animals are the primary source of image quality degradation in dynamic imaging studies, especially when using phase-resolved imaging modalities such as spectral-domain optical coherence tomography (SD-OCT), whose phase signal is very sensitive to movements of the sample. This study demonstrates a method with which to compensate for motion artifacts in dynamic SD-OCT imaging of the rodent cerebral cortex. We observed that respiratory and cardiac motions mainl...

  12. Extended scan depth optical coherence tomography for evaluating ocular surface shape

    OpenAIRE

    Shen, Meixiao; Cui, Lele; Li, Ming; Zhu, Dexi; Wang, Michael R.; Wang, Jianhua

    2011-01-01

    Spectral domain optical coherence tomography (SD-OCT) with extended scan depth makes it possible for quantitative measurement of the entire ocular surface shape. We proposed a novel method for ocular surface shape measurement using a custom-built anterior segment SD-OCT, which will serve on the contact lens fitting. A crosshair alignment system was applied to reduce the misalignment and tilting of the eye. An algorithm was developed to automatically segment the ocular surface. We also describ...

  13. GPU-Accelerated Finite Element Method for Modelling Light Transport in Diffuse Optical Tomography

    OpenAIRE

    Martin Schweiger

    2011-01-01

    We introduce a GPU-accelerated finite element forward solver for the computation of light transport in scattering media. The forward model is the computationally most expensive component of iterative methods for image reconstruction in diffuse optical tomography, and performance optimisation of the forward solver is therefore crucial for improving the efficiency of the solution of the inverse problem. The GPU forward solver uses a CUDA implementation that evaluates on the graphics hardware th...

  14. Large-volume optical coherence tomography with real-time correction of geometric distortion artifacts

    OpenAIRE

    Jeught, Sam; Buytaert, Jan A. N.; Bradu, Adrian; Podoleanu, Adrian Gh; Dirckx, Joris J. J.

    2012-01-01

    Large-volume optical coherence tomography (OCT)-setups employ scanning mirrors and suffer from non-linear geometric distortion artifacts in which the degree of distortion is determined by the maximum angles over which the mirrors rotate. In this chapter, we describe a straightforward approach to correct for these distortion artifacts, creating an alternative to previously reported ray-tracing schemes that are unable to apply these corrections in real-time. By implementing th...

  15. Characterization of coronary plaques with combined use of intravascular ultrasound, virtual histology and optical coherence tomography

    OpenAIRE

    José Calabuig; Joaquín Barba; José Antonio Páramo; Miguel Artaiz; Isabel Coma-Canella; Guillermo Sánchez-Elvira

    2010-01-01

    According to post-mortem studies, luminal thrombosis occurs from plaque rupture, erosion and calcified nodules. In vivo studies have found thin cap fibroatheroma (TCFA) as the main vulnerable lesion, prone to rupture. Few data about other post-mortem lesions have been reported in vivo. Our main objective is to characterize in vivo the coronary plaques with intravascular ultrasound-virtual histology (IVUS-VH) and optical coherence tomography (OCT), in order to detect not only thin cap fibroath...

  16. Use of Optical Coherence Tomography to Evaluate Visual Acuity and Visual Field Changes in Dengue Fever

    OpenAIRE

    Rhee, Taek Kwan; Han, Jung Il

    2014-01-01

    Dengue fever is a viral disease that is transmitted by mosquitoes and affects humans. In rare cases, dengue fever can cause visual impairment, which usually occurs within 1 month after contracting dengue fever and ranges from mild blurring of vision to severe blindness. Visual impairment due to dengue fever can be detected through angiography, retinography, optical coherence tomography (OCT) imaging, electroretinography, event electroencephalography (visually evoked potentials), and visual fi...

  17. Assessment and In Vivo Scoring of Murine Experimental Autoimmune Uveoretinitis Using Optical Coherence Tomography

    OpenAIRE

    Chu, C. J.; Herrmann, P.; Carvalho, L. S.; Liyanage, S. E.; Bainbridge, J. W.; Ali, R. R.; Dick, A. D.; Luhmann, U. F.

    2013-01-01

    Despite advances in clinical imaging and grading our understanding of retinal immune responses and their morphological correlates in experimental autoimmune uveoretinitis (EAU), has been hindered by the requirement for post-mortem histology. To date, monitoring changes occurring during EAU disease progression and evaluating the effect of therapeutic intervention in real time has not been possible. We wanted to establish whether optical coherence tomography (OCT) could detect intraretinal chan...

  18. Utility of Optical Coherence Tomography to Assess a Hazy Intracoronary Image after Percutaneous Coronary Intervention

    OpenAIRE

    Carrizo, Sebastian; Salinas, Pablo; Jimenez-valero, Santiago; Moreno, Raul

    2013-01-01

    Although its use in daily practice is not common, optical coherence tomography (OCT) is a powerful research tool in invasive cardiology. This report describes a hazy angiography image after percutaneous coronary intervention that has been assessed using OCT. Based on the results of the OCT, the patient underwent an elective coronary angioplasty with standard anticoagulation. After implantation of the stent, an intracoronary hazy image was seen on angiography. The use of OCT permitted a correc...

  19. Optical coherence tomography study of adult vitelliform macular detachment in a patient with basal laminar drusen.

    OpenAIRE

    Khan, J.; Chong, V.

    2010-01-01

    To report the morphological data of adult vitelliform macular detachment in a patient with basal laminar drusen using optical coherence tomography (OCT-3) as an observational case report. A 70-year-old man presented with adult vitelliform macular detachment and basal laminar drusen underwent fundus biomicroscopy, fundus fluorescein angiography and OCT-3. Fundus examination showed bilateral yellow subretinal macula deposits with associated basal laminar drusen. Examination with OCT revealed ar...

  20. Unusual optical coherence tomography and fundus autofluorescence findings of eclipse retinopathy

    OpenAIRE

    Li, Kun-hsien; Chen, San-ni; Hwang, Jiunn-feng; Lin, Chun-ju

    2012-01-01

    A 63-year-old female patient complained of dimness in the central field of vision in the left eye after viewing an annular partial eclipse without adequate eye protection on 22 July 2009. Fundoscopy showed a wrinkled macular surface. Fundus autofluorescence study revealed well-demarcated hyperautofluorescence at the fovea. Optical coherence tomography demonstrated tiny intraretinal cysts. Fluorescein angiography and indocyanine green angiography were unremarkable. Epimacular membrane develope...

  1. “En-Face” Spectral-Domain Optical Coherence Tomography Findings in Multiple Evanescent White Dot Syndrome

    OpenAIRE

    Flore De bats; Benjamin Wolff; Vivien Vasseur; Aude Affortit; Laurent Kodjikian; José-Alain Sahel; Martine Mauget-faÿsse

    2014-01-01

    Purpose. The recent use of “en-face” enhanced-depth imaging spectral-domain optical coherence tomography (EDI SD-OCT) helps distinguish the retinal layers involved in the physiopathology of multiple evanescent white dot syndrome (MEWDS). Methods. Four patients presenting with MEWDS underwent a comprehensive ocular examination including C-scan (“en-face”) EDI SD-OCT at the initial visit and during follow-up. Results. C-scans combined with the other multimodal imaging enabled the visual...

  2. Spectral domain optical coherence tomography imaging of punctate outer retinal toxoplasmosis

    OpenAIRE

    Lujan, Brandon J.

    2014-01-01

    Punctate outer retinal toxoplasmosis is a recognized phenotype of this common ocular parasite. We present a case presenting with poor visual acuity, but with prompt treatment regaining excellent vision by the final time point. Imaging demonstrates progression of an active lesion adjacent to an inactive retinal scar with color photography, fluorescein angiography, and Spectral Domain Optical Coherence Tomography (SD-OCT). SD-OCT imaging of the chorioretinal scar demonstrated alternating hypert...

  3. Blunt ocular trauma at the posterior pole in optical coherence tomography and fluorescein angiography

    International Nuclear Information System (INIS)

    Blunt ocular trauma at the posterior pole may involve a variety of retinal structures. We examined the most frequent retinal trauma (choroidal folds, commotion retinae, choroidal rupture, valsalva retinopathy, PPE-tears, Purtscher's Retinopathy etc.) by optical coherence tomography (OCT). The damaged pre-, intra- or subretinal structures were clearly visible. The OCT is during acute and chronic phases of different traumatic events an important diagnostic tool. (author)

  4. Chorioretinal architecture in Aicardi syndrome: An optical coherence tomography and fluorescein angiography study

    OpenAIRE

    Martel, Joseph N.; Rutar, Tina; Lujan, Brandon J.; Alba Campomanes, Alejandra

    2011-01-01

    Aicardi syndrome is a rare congenital disorder with a classic triad of infantile spasms, chorioretinal lacunae, and agenesis of the corpus callosum. We report the use of fluorescein angiography and spectral domain optical coherence tomography to examine the posterior segment structures in an 8-month-old girl with Aicardi syndrome. Most of the observed features correlated with previously published histopathological findings, but inner-nuclear layer cysts have not been previously described. To ...

  5. Optical coherence tomography imaging in asymptomatic patients with carotid artery stenosis

    International Nuclear Information System (INIS)

    Assessment and treatment plan for asymptomatic patients with carotid stenosis are based on angiography at the present time. However, angiography or other imaging modalities are limited with their resolution to detect high-risk plaque features. Intravascular optical coherence tomography (IVOCT) recently emerged as a novel imaging modality with a unique resolution to identify vulnerable plaque characteristics. We report use of IVOCT in two separate asymptomatic patients with carotid stenosis with two different plaque types

  6. Three-dimensional quantitative coronary angiography and the registration with intravascular ultrasound and optical coherence tomography

    OpenAIRE

    Tu, Shengxian

    2012-01-01

    This thesis proposes several new algorithms including X-ray angiographic image enhancement, three-dimensional (3D) angiographic reconstruction, angiographic overlap prediction, and the co-registration of X-ray angiography with intracoronary imaging devices, such as intravascular ultrasound (IVUS) and optical coherence tomography (OCT). The algorithms were integrated into prototype software packages that were validated at a number of clinical centers. The feasibility of using such software pac...

  7. Optical coherence tomography imaging in asymptomatic patients with carotid artery stenosis

    Energy Technology Data Exchange (ETDEWEB)

    Cilingiroglu, Mehmet, E-mail: Mcilingiroglu@yahoo.com [University of Pittsburgh Heart and Vascular Institute, Pittsburgh, PA (United States); Hakeem, Abdul [William Beaumont Hospital, Royal Oak, MI (United States); Feldman, Marc [University of Texas Health Sciences Center at San Antonio, San Antonio, TX (United States); Wholey, Mark [University of Pittsburgh Heart and Vascular Institute, Pittsburgh, PA (United States)

    2013-01-15

    Assessment and treatment plan for asymptomatic patients with carotid stenosis are based on angiography at the present time. However, angiography or other imaging modalities are limited with their resolution to detect high-risk plaque features. Intravascular optical coherence tomography (IVOCT) recently emerged as a novel imaging modality with a unique resolution to identify vulnerable plaque characteristics. We report use of IVOCT in two separate asymptomatic patients with carotid stenosis with two different plaque types.

  8. Optical coherence tomography fast versus regular macular thickness mapping in diabetic retinopathy

    OpenAIRE

    Ceklic, Lala; Maar, Noemi; Neubauer, Aljoscha S.

    2008-01-01

    Objective: The purpose of the study was to investigate if absolute values and reproducibility of thickness maps obtained from 2 optical coherence tomography (OCT) scanning protocols, regular high-resolution and fast low-density mode, differ in patients with diabetic macular edema. Methods: A total of 26 consecutive patients undergoing fluorescein angiography and Stratus OCT scanning for the evaluation of diabetic macular edema at the Departments of Ophthalmology in Munich and Vienna were incl...

  9. Aspects of Optical Coherence Tomography (OCT) in Healthy Eyes and Eyes with Retinal Diseases

    OpenAIRE

    Eriksson, Urban

    2010-01-01

    Optical coherence tomography (OCT) is a technique in which cross-sectional images from intraocular tissue can be obtained. The quantitative and qualitative examinations are used for evaluating retinal diseases. Conventional OCT (Stratus) is mainly used, but the new Spectral domain (Cirrus) OCT, which has improved technology, may provide more reliable measurements. The aim of the study was to collect normal values of macular thickness in children and adults and to evaluate the effect of age an...

  10. Tiny endoscopic optical coherence tomography probe driven by a miniaturized hollow ultrasonic motor

    OpenAIRE

    Chen, Tianyuan; Zhang, Ning; Huo, Tiancheng; Wang, Chengming; Zheng, Jing-gao; Zhou, Tieying; Xue, Ping

    2013-01-01

    We present an endoscopic probe for optical coherence tomography (OCT) equipped with a miniaturized hollow ultrasonic motor that rotates the objective lens and provides an internal channel for the fiber to pass through, enabling 360 deg unobstructed circumferential scanning. This probe has an outer diameter of 1.5 mm, which is ultra-small for motorized probes with an unobstructed view in distal scanning endoscopic OCT. Instead of a mirror or prism, a customized aspheric right-angle lens is uti...

  11. Assessing atherosclerotic plaque morphology: comparison of optical coherence tomography and high frequency intravascular ultrasound.

    OpenAIRE

    Brezinski, M. E.; Tearney, G. J.; Weissman, N. J.; Boppart, S. A.; Bouma, B. E.; Hee, M. R.; Weyman, A. E.; Swanson, E. A.; Southern, J. F.; Fujimoto, J. G.

    1997-01-01

    BACKGROUND: OCT can image plaque microstructure at a level of resolution not previously demonstrated with other imaging techniques because it uses infrared light rather than acoustic waves. OBJECTIVES: To compare optical coherence tomography (OCT) and intravascular ultrasound (IVUS) imaging of in vitro atherosclerotic plaques. METHODS: Segments of abdominal aorta were obtained immediately before postmortem examination. Images of 20 sites from five patients were acquired with OCT (operating at...

  12. Intravascular Optical-Resolution Photoacoustic Tomography with a 1.1 mm Diameter Catheter

    OpenAIRE

    Bai, Xiaosong; Gong, Xiaojing; Hau, William; Lin, Riqiang; Zheng, Jiaxiang; Liu, Chengbo; Zeng, Chengzhi; Zou, Xin; Zheng, Hairong; Song, Liang

    2014-01-01

    Photoacoustic imaging is an emerging technology that can provide anatomic, functional, and molecular information about biological tissue. Intravascular spectroscopic and molecular photoacoustic imaging can potentially improve the identification of atherosclerotic plaque composition, the detection of inflammation, and ultimately the risk stratification of atherosclerosis. In this study, a first-of-its-kind intravascular optical-resolution photoacoustic tomography (OR-PAT) system with a 1.1 mm ...

  13. Imaging actinic keratosis by high-definition optical coherence tomography. Histomorphologic correlation : a pilot study

    DEFF Research Database (Denmark)

    Boone, Marc A L M; Norrenberg, Sarah

    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 ?m 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. The surrounding normal looking skin has been used as control group. In lesional skin, dyskeratotic and atypical keratinocytes could be noticed with this new technique. An atypical honeycomb pattern in variable degree or a disarranged epidermal pattern could be observed. A good correlation between the dimension of atypia and/or disarrangement of the spinous-granular layer on en face images and the histopathological grading could be demonstrated. Relevant cross-sectional imaging criteria could be defined for the different histopathological variants of actinic keratoses. The surrounding skin displayed features of photodamage. Using features already suggested by reflectance confocal microscopy, the study implies that high-definition optical coherence tomography facilitates in vivo diagnosis of actinic keratosis and allows the grading of different actinic keratosis lesions for increased clinical utility.

  14. High-Definition Optical Coherence Tomography for the in vivo Detection of Demodex Mites

    OpenAIRE

    Maier, T.; Sattler, E.; Braun-falco, M.; Ruzicka, Thomas; Berking, C.

    2012-01-01

    Background: Demodex mites are involved in different skin diseases and are commonly detected by skin scrape tests or superficial biopsies. A new high-definition optical coherence tomography (HD-OCT) with high lateral and axial resolution in a horizontal (en-face) and vertical (slice) imaging mode might offer the possibility of noninvasive and fast in vivo examination of demodex mites. Methods: Twenty patients with demodex-related skin diseases and 20 age- and gender-matched healthy controls we...

  15. Modelling the normal retinal nerve fibre layer thickness as measured by Stratus optical coherence tomography.

    OpenAIRE

    Hougaard, Jesper; Ostenfeld, Carl; Heijl, Anders; Bengtsson, Boel

    2006-01-01

    Background: The variation in retinal nerve fibre layer thickness (RNFLT) as measured by Stratus optical coherence tomography (OCT) in healthy subjects may be reduced when the effect on RNFLT measurements of factors other than disease is corrected for, and this may improve the diagnostic accuracy in glaucoma. With this perspective we evaluated the isolated and combined effects of factors potentially affecting the Stratus OCT RNFLT measurements in healthy subjects. Methods: We included 178 heal...

  16. Handheld miniature probe integrating diffuse optical tomography with photoacoustic imaging through a MEMS scanning mirror.

    Science.gov (United States)

    Yang, Hao; Xi, Lei; Samuelson, Sean; Xie, Huikai; Yang, Lily; Jiang, Huabei

    2013-03-01

    We describe a novel dual-modality imaging approach that integrates diffuse optical tomography (DOT) and photoacoustic imaging (PAI) through a miniaturized handheld probe based on microelectromechanical systems (MEMS) scanning mirror. We validate this dual-modal DOT/PAI approach using extensive phantom experiments, and demonstrate its application for tumor imaging using tumor-bearing mice systematically injected with targeted contrast agents. PMID:23504287

  17. Complex Ambiguity-Free Fourier Domain Optical Coherence Tomography through Transverse Scanning

    OpenAIRE

    Leitgeb, R. A.; Michaely, R.; Lasser, T.; Sekhar, S. C.

    2007-01-01

    We introduce a simple and cheap method for phase-shifting Fourier domain optical coherence tomography (FDOCT) that does not need additional devices and can easily be implemented. A small beam offset at the fast beam-scanning mirror introduces a causal phase shift, which can be used for B-scan-based complex image reconstruction. We derive the conditions for optimal conjugate suppression and demonstrate the method on human skin in vivo for spectrometer-based FDOCT operating at 1300 nm employing...

  18. Imaging of skin microvessels with optical coherence tomography: potential uses in port wine stains

    OpenAIRE

    Zhou, Yang; Yin, Daiqiang; Xue, Ping; Huang, Naiyan; Qiu, Haixia; Wang, Ying; Zeng, Jing; Ding, Zhihua; Gu, Ying

    2012-01-01

    The knowledge of vascular structures of port wine stains (PWSs) may be useful to select treatment doses and improve therapeutic efficacy. Biopsies are impractical to implement, therefore, it is necessary to develop non-invasive techniques for morphological evaluation. This study aimed to evaluate the application of a novel optical coherence tomography (OCT) system to characterize the vascular structures of PWSs. First, OCT images were obtained from the skin of healthy rabbit ears and compared...

  19. Depth-resolved imaging of functional activation in the rat cerebral cortex using optical coherence tomography

    OpenAIRE

    Aguirre, A. D.; Chen, Y.; Fujimoto, J. G.; Ruvinskaya, L.; Devor, A.; Boas, D. A.

    2006-01-01

    Co-registered optical coherence tomography (OCT) and video microscopy of the rat somatosensory cortex were acquired simultaneously through a thinned skull during forepaw electrical stimulation. Fractional signal change measured by OCT revealed a functional signal time course corresponding to the hemodynamic signal measurement made with video microscopy. OCT can provide high-resolution, cross-sectional images of functional neurovascular activation and may offer a new tool for basic neuroscienc...

  20. Monitoring early tumor response to drug therapy with diffuse optical tomography

    OpenAIRE

    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 p...

  1. Imaging gold nanorods in excised human breast carcinoma by spectroscopic optical coherence tomography

    OpenAIRE

    Oldenburg, Amy L.; Hansen, Matthew N.; Ralston, Tyler S.; Wei, Alexander; Boppart, Stephen A.

    2009-01-01

    Plasmon-resonant gold nanorods (GNRs) can serve as imaging agents for spectroscopic optical coherence tomography (SOCT). The aspect ratio of the GNRs are adjusted for maximum absorption in the far red to create a partial spectral overlap with the low-wavelength edge of the near-infrared SOCT imaging band. The spectroscopic absorption profile of the GNRs is incorporated into a depth-resolved algorithm for mapping the relative GNR density within OCT images. This technique enables us to image GN...

  2. Volumetric microvascular imaging of human retina using optical coherence tomography with a novel motion contrast technique

    OpenAIRE

    Fingler, Jeff; Zawadzki, Robert J.; Werner, John S.; Schwartz, Dan; Fraser, Scott E.

    2009-01-01

    Phase variance-based motion contrast imaging is demonstrated using a spectral domain optical coherence tomography system for the in vivo human retina. This contrast technique spatially identifies locations of motion within the retina primarily associated with vasculature. Histogram-based noise analysis of the motion contrast images was used to reduce the motion noise created by transverse eye motion. En face summation images created from the 3D motion contrast data are presented with segmenta...

  3. High-resolution optical coherence tomography visualization of LASIK flap displacement

    OpenAIRE

    Salaroli, Camila Hayde?e Rosas; Li, Yan; Huang, David

    2009-01-01

    Uneventful myopic laser in situ keratomileusis (LASIK) was performed in both eyes of a 33-year-old woman. Two weeks after LASIK, examination of the left eye revealed flap striae radiating inferonasally from the superior hinge. The flap was relifted and repositioned to remove the irregular astigmatism and reduce the striae. Before the flap was relifted, Fourier-domain optical coherence tomography (FD-OCT) showed the gap at the temporal flap, which had not been detected by biomicroscopy. After ...

  4. Optical Coherence Tomography and Its Role in Mohs Micrographic Surgery: A Case Report

    OpenAIRE

    Chan, C. Stanley; Rohrer, Thomas E.

    2012-01-01

    Optical coherence tomography (OCT) is an imaging technology with the potential to provide high-resolution images of the skin non-invasively. With this device, it is possible to identify a host of skin structures including tumors. In this case report, we demonstrate the use of an OCT device in delineating a lateral tumor margin of an ill-defined basal cell carcinoma prior to Mohs micrographic surgery. Following surgery, the OCT images are compared to histologic sections to confirm their accura...

  5. Spectral-domain optical coherence tomography imaging of macula-off rhegmatogenous retinal detachment

    OpenAIRE

    Sridhar J; Hw, Flynn Jr

    2014-01-01

    Jayanth Sridhar, Harry W Flynn Jr Department of Ophthalmology, Bascom Palmer Eye Institute, Miami, FL, USA Abstract: The timing of repair and the utility of spectral-domain optical coherence tomography (SD-OCT) for macula-off retinal detachment remains a controversial issue. Four patients who presented with macula-off retinal detachment underwent repair at various time points after symptom onset. Postoperative SD-OCT of the macula demonstrated correlation with final visual acuity. Keywords:...

  6. Predicting Visual Outcomes for Macula-Off Rhegmatogenous Retinal Detachment with Optical Coherence Tomography

    OpenAIRE

    Suzuki, Noriyuki; Kunikata, Hiroshi; Aizawa, Naoko; Abe, Toshiaki; Nakazawa, Toru

    2014-01-01

    Purpose. We evaluated the ability of novel optical coherence tomography (OCT) parameters to predict postoperative best-corrected visual acuity (BCVA) in macula-off rhegmatogenous retinal detachment (RRD) eyes. Methods. We reviewed the medical records of 56 consecutive eyes with macula-off RRD. Clinical findings were analyzed including the relationship between preoperative OCT findings and 6-month postoperative BCVA. Results. Six-month postoperative BCVA was significantly correlated with preop...

  7. Refractive Index Measurement of the Isolated Crystalline Lens Using Optical Coherence Tomography

    OpenAIRE

    Uhlhorn, Stephen R.; Borja, David; Manns, Fabrice; Parel, Jean-marie

    2008-01-01

    An optical coherence tomography system has been developed that was designed specifically for imaging the isolated crystalline lens. Cross-sectional OCT images were recorded on 40 lenses from 32 human donors with an age range of 6 – 82 years. A method has been developed to measure the axial thickness and average refractive index of the lens from a single recorded image. The measured average group refractive index at the measurement wavelength of 825 nm was converted to the average phase refr...

  8. Development of optical coherence tomography for monitoring the glaucoma laser surgery

    OpenAIRE

    Bayleyegn, Masreshaw-demelash

    2012-01-01

    The ability of optical coherence tomography (OCT) to deliver tomographic images of biological tissues in vivo non-invasively and in real-time has been a growing interest in many biomedical applications, mainly in ophthalmology for imaging the retina and the anterior segment of the eye. However, developing high-resolution OCT for imaging strongly scattering biological tissues like sclera and edematous cornea has still been the main challenge. In this PhD work, an ultrahigh-resolution (< 4 µm)...

  9. Endovascular optical coherence tomography intensity kurtosis: visualization of vasa vasorum in porcine carotid artery

    OpenAIRE

    Cheng, Kyle H. Y.; Sun, Cuiru; Vuong, Barry; Lee, Kenneth K. C.; Mariampillai, Adrian; Marotta, Thomas R.; Spears, Julian; Montanera, Walter J.; Herman, Peter R.; Kiehl, Tim-rasmus; Standish, Beau A.; Yang, Victor X. D.

    2012-01-01

    Application of speckle variance optical coherence tomography (OCT) to endovascular imaging faces difficulty of extensive motion artifacts inherently associated with arterial pulsations in addition to other physiological movements. In this study, we employed a technique involving a fourth order statistical method, kurtosis, operating on the endovascular OCT intensity images to visualize the vasa vasorum of carotid artery in vivo and identify its flow dynamic in a porcine model. The intensity k...

  10. Multilayer thin-film phantoms for axial contrast transfer function measurement in optical coherence tomography

    OpenAIRE

    Agrawal, Anant; Chen, Chao-wei; Baxi, Jigesh; Chen, Yu; Pfefer, T. Joshua

    2013-01-01

    In optical coherence tomography (OCT), axial resolution is one of the most critical parameters impacting image quality. It is commonly measured by determining the point spread function (PSF) based on a specular surface reflection. The contrast transfer function (CTF) provides more insights into an imaging system’s resolving characteristics and can be readily generated in a system-independent manner, without consideration for image pixel size. In this study, we developed a test method for de...

  11. OPTICAL COHERENCE TOMOGRAPHY HEART TUBE IMAGE DENOISING BASED ON CONTOURLET TRANSFORM

    OpenAIRE

    Guo, Qing; Sun, Shuifa; Dong, Fangmin; Gao, Bruce Z.; Wang, Rui

    2012-01-01

    Optical Coherence Tomography(OCT) gradually becomes a very important imaging technology in the Biomedical field for its noninvasive, nondestructive and real-time properties. However, the interpretation and application of the OCT images are limited by the ubiquitous noise. In this paper, a denoising algorithm based on contourlet transform for the OCT heart tube image is proposed. A bivariate function is constructed to model the joint probability density function (pdf) of the coefficient and it...

  12. Application of the vector Monte-Carlo method in polarisation optical coherence tomography

    International Nuclear Information System (INIS)

    The vector Monte-Carlo method is developed and applied to polarisation optical coherence tomography. The basic principles of simulation of the propagation of polarised electromagnetic radiation with a small coherence length are considered under conditions of multiple scattering. The results of numerical simulations for Rayleigh scattering well agree with the Milne solution generalised to the case of an electromagnetic field and with theoretical calculations in the diffusion approximation. (special issue devoted to multiple radiation scattering in random media)

  13. Investigation of detection limits for diffuse optical tomography systems: I. Theory and experiment

    International Nuclear Information System (INIS)

    We present a statistical test using simulated photon migration data and a noise model derived from the hardware of a particular diffuse optical tomography system to predict its detection limits. Our method allows us to assess the spatial distribution of the detection sensitivity of arbitrary geometries and noise without requiring phantom measurements and reconstructions. We determine the minimal detectable lesion size at selected lesion positions and compare the predicted results with phantom measurements carried out in a cup geometry.

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

    OpenAIRE

    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, w...

  15. Quantitative comparison of analysis methods for spectroscopic optical coherence tomography: reply to comment.

    Science.gov (United States)

    Bosschaart, Nienke; van Leeuwen, Ton G; Aalders, Maurice C G; Faber, Dirk J

    2014-09-01

    We reply to the comment by Kraszewski et al on "Quantitative comparison of analysis methods for spectroscopic optical coherence tomography." We present additional simulations evaluating the proposed window function. We conclude that our simulations show good qualitative agreement with the results of Kraszewski, in support of their conclusion that SOCT optimization should include window shape, next to choice of window size and analysis algorithm. PMID:25401016

  16. Comment on “Quantitative comparison of analysis methods for spectroscopic optical coherence tomography

    OpenAIRE

    Kraszewski, Maciej; Trojanowski, Micha?; Stra?kowski, Marcin R.

    2014-01-01

    In a recent paper by Bosschaart et al. [Biomed. Opt. Express 4, 2570 (2013)] various algorithms of time-frequency signal analysis have been tested for their performance in blood analysis with spectroscopic optical coherence tomography (sOCT). The measurement of hemoglobin concentration and oxygen saturation based on blood absorption spectra have been considered. Short time Fourier transform (STFT) was found as the best method for the measurement of blood absorption spectra. STF...

  17. Comparison of different metrics for analysis and visualization in spectroscopic optical coherence tomography

    OpenAIRE

    Jaedicke, Volker; Agcaer, Semih; Robles, Francisco E.; Steinert, Marian; Jones, David; Goebel, Sebastian; Gerhardt, Nils C.; Welp, Hubert; Hofmann, Martin R.

    2013-01-01

    Spectroscopic Optical Coherence Tomography (S-OCT) extracts depth resolved spectra that are inherently available from OCT signals. The back scattered spectra contain useful functional information regarding the sample, since the light is altered by wavelength dependent absorption and scattering caused by chromophores and structures of the sample. Two aspects dominate the performance of S-OCT: (1) the spectral analysis processing method used to obtain the spatially-resolved spectroscopic inform...

  18. 3D shape based reconstruction of experimental data in Diffuse Optical Tomography

    OpenAIRE

    Zacharopoulos, A.; Schweiger, M.; Kolehmainen, V.; Arridge, S.

    2009-01-01

    Diffuse optical tomography (DOT) aims at recovering three-dimensional images of absorption and scattering parameters inside diffusive body based on small number of transmission measurements at the boundary of the body. This image reconstruction problem is known to be an ill-posed inverse problem, which requires use of prior information for successful reconstruction. We present a shape based method for DOT, where we assume a priori that the unknown body consist of disjoint subdomains with diff...

  19. Correlation of spectral domain optical coherence tomography findings in acute central serous chorioretinopathy with visual acuity

    OpenAIRE

    Nair U; Ganekal S; Soman M; Kg, Nair

    2012-01-01

    Unnikrishnan Nair,1 Sunil Ganekal,2 Manoj Soman,1 KGR Nair11Chaithanya Eye Hospital and Research Institute, Trivandrum, Kerala, India; 2Nayana Super Specialty Eye Hospital and Research Center, Davangere, Karnataka, IndiaPurpose: To evaluate the structural changes in the acute phase of central serous chorioretinopathy and after its resolution, using spectral domain optical coherence tomography, to correlate these tomographic changes with visual acuity (VA).Method: This was a prospective study ...

  20. In vivo Optical Coherence Tomography of Light-Driven Melanosome Translocation in Retinal Pigment Epithelium

    OpenAIRE

    Qiu-Xiang Zhang; Rong-Wen Lu; Messinger, Jeffrey D.; Curcio, Christine A.; Vincenzo Guarcello; Xin-Cheng Yao

    2013-01-01

    Optical coherence tomography (OCT) may revolutionize fundamental investigation and clinical management of age-related macular degeneration and other eye diseases. However, quantitative OCT interpretation is hampered due to uncertain sub-cellular correlates of reflectivity in the retinal pigment epithelium (RPE) and photoreceptor. The purpose of this study was twofold: 1) to test OCT correlates in the RPE, and 2) to demonstrate the feasibility of longitudinal OCT monitoring of sub-cellular RPE...

  1. Active tremor cancellation by a “Smart” handheld vitreoretinal microsurgical tool using swept source optical coherence tomography

    OpenAIRE

    Song, Cheol; Gehlbach, Peter L.; Kang, Jin U.

    2012-01-01

    Abstract: Microsurgeons require dexterity to make precise and stable maneuvers to achieve surgical objectives and to minimize surgical risks during freehand procedures. This work presents a novel, common path, swept source optical coherence tomography-based “smart” micromanipulation aided robotic-surgical tool (SMART) that actively suppresses surgeon hand tremor. The tool allows enhanced tool tip stabilization, more accurate targeting and the potential to lower surgical risk. Freehand per...

  2. Swept Source Optical Coherence Tomography based Smart Handheld Vitreoretinal Microsurgical Tool for Tremor Suppression

    OpenAIRE

    Song, Cheol; Gehlbach, Peter L.; Kang, Jin U.

    2012-01-01

    Microsurgeons require the ability to make precise and stable maneuvers in order to achieve surgical objectives and to minimize surgical risks during freehand microsurgical procedures. This work presents a novel common path swept source optical coherence tomography based smart surgical tool that suppresses hand tremor. It allows enhanced tool tip stabilization, more accurate targeting and may lower surgical risk. Here the one dimensional motion tremor of a surgeon’s hand is assessed by the s...

  3. Visualization of peripheral pulmonary artery red thrombi utilizing optical coherence tomography

    International Nuclear Information System (INIS)

    Optical coherence tomography (OCT) is a new imaging technique capable of obtaining high-resolution intravascular images and has been used in interventional cardiology. However, an application of OCT in pulmonary arteries had seldom been documented. In this case, OCT imaging is performed in peripheral pulmonary arteries and shows mural red thrombi. Subsequently, the red thrombi are aspirated and confirmed by a histological examination. These findings suggest that OCT may be a useful tool to depict peripheral pulmonary artery thrombi.

  4. Ten Years of Severe Vitreomacular Traction Syndrome without Functional Damage Demonstrated by Optical Coherence Tomography

    OpenAIRE

    Andrea Russo; Marco Zagari; Francesco Occhipinti; Mario Toro; Maurizio Giacinto Uva; Teresio Avitabile; Michele Reibaldi

    2011-01-01

    Introduction. To describe anatomical and functional features in one patient with 10 years of severe vitreomacular traction syndrome (VTS) without functional damage demonstrated by optical coherence tomography (OCT). Patient and Methods. One patient with a history of 10 years VTS, with best-corrected visual acuity of 20/32, was followed up with OCT. Follow-up examinations, 3 months for the first year after diagnosis and every 6 months for the subsequent years, were performed. Results. Follow-u...

  5. Performance Analysis of Reconstruction Techniques for Frequency-Domain Optical-Coherence Tomography

    OpenAIRE

    Seelamantula, C. S.; Unser, M.

    2010-01-01

    We address the issue of noise robustness of reconstruction techniques for frequency-domain optical-coherence tomography (FDOCT). We consider three reconstruction techniques: Fourier, iterative phase recovery, and cepstral techniques. We characterize the reconstructions in terms of their statistical bias and variance and obtain approximate analytical expressions under the assumption of small noise. We also perform Monte Carlo analyses and show that the experimental results are in agreement wit...

  6. A Case of Ocular Toxoplasmosis Imaged with Spectral Domain Optical Coherence Tomography

    OpenAIRE

    Cho, Doo Young; Nam, Wooho

    2012-01-01

    A 54-year-old man presented with blurred central vision in the right eye of two weeks' duration. On presentation, visual acuity was 40 / 50 in the right eye and fundus examination showed a whitish-yellow inflammatory lesion near an atrophic, pigmented retinochoroidal scar located in the superotemporal quadrant. Serologic assessment was negative for IgM, but serum IgG to toxoplasma was elevated. Spectral domain optical coherence tomography (SD-OCT) revealed increased reflectivity from the inne...

  7. In vivo volumetric imaging of chicken retina with ultrahigh-resolution spectral domain optical coherence tomography

    OpenAIRE

    Moayed, Alireza Akhlagh; Hariri, Sepideh; Song, Eun Sun; Choh, Vivian; Bizheva, Kostadinka

    2011-01-01

    The chicken retina is an established animal model for myopia and light-associated growth studies. It has a unique morphology: it is afoveate and avascular; oxygen and nutrition to the inner retina is delivered by a vascular tissue (pecten) that protrudes into the vitreous. Here we present, to the best of our knowledge, the first in vivo, volumetric high-resolution images of the chicken retina. Images were acquired with an ultrahigh-resolution optical coherence tomography (UHROCT) system with ...

  8. Photoreceptor inner segment ellipsoid band integrity on spectral domain optical coherence tomography

    OpenAIRE

    Saxena, Sandeep; Srivastav, Khushboo; Cheung, Chui M.; Ng, Joanne Yw; Lai, Timothy Yy

    2014-01-01

    Spectral domain optical coherence tomography cross-sectional imaging of the macula has conventionally been resolved into four bands. However, some doubts were raised regarding authentication of the existence of these bands. Recently, a number of studies have suggested that the second band appeared to originate from the inner segment ellipsoids of the foveal cone photoreceptors, and therefore the previously called inner segment-outer segment junction is now referred to as inner segment ellipso...

  9. Compressive sensing with dispersion compensation on non-linear wavenumber sampled spectral domain optical coherence tomography

    OpenAIRE

    Xu, Daguang; Huang, Yong; Kang, Jin U.

    2013-01-01

    We propose a novel compressive sensing (CS) method on spectral domain optical coherence tomography (SDOCT). By replacing the widely used uniform discrete Fourier transform (UDFT) matrix with a new sensing matrix which is a modification of the non-uniform discrete Fourier transform (NUDFT) matrix, it is shown that undersampled non-linear wavenumber spectral data can be used directly in the CS reconstruction. Thus k-space grid filling and k-linear mask calibration which were proposed to obtain ...

  10. Retinal tumor imaging and volume quantification in mouse model using spectral-domain optical coherence tomography?

    OpenAIRE

    Ruggeri, Marco; Tsechpenakis, Gavriil; Jiao, Shuliang; Jockovich, Maria Elena; Cebulla, Colleen; Hernandez, Eleut; Murray, Timothy G.; Puliafito, Carmen A.

    2009-01-01

    We have successfully imaged the retinal tumor in a mouse model using an ultra-high resolution spectral-domain optical coherence tomography (SD-OCT) designed for small animal retinal imaging. For segmentation of the tumor boundaries and calculation of the tumor volume, we developed a novel segmentation algorithm. The algorithm is based on parametric deformable models (active contours) and is driven by machine learning-based region classification, namely a Conditional Random Field. With this al...

  11. Imaging of basal cell carcinoma by high-definition optical coherence tomography : histomorphological correlation. A pilot study

    DEFF Research Database (Denmark)

    Boone, M A L M; Norrenberg, S

    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, with micrometre resolution in both transversal and axial directions, enabling visualization of individual cells up to a depth of around 570 ?m, and filling the imaging gap between conventional optical coherence tomography (OCT) and reflectance confocal microscopy (RCM).

  12. Intravascular atherosclerotic imaging with combined fluorescence and optical coherence tomography probe based on a double-clad fiber combiner

    OpenAIRE

    Liang, Shanshan; Saidi, Arya; Jing, Joe; Liu, Gangjun; Li, Jiawen; Zhang, Jun; Sun, Changsen; Narula, Jagat; Chen, Zhongping

    2012-01-01

    We developed a multimodality fluorescence and optical coherence tomography probe based on a double-clad fiber (DCF) combiner. The probe is composed of a DCF combiner, grin lens, and micromotor in the distal end. An integrated swept-source optical coherence tomography and fluorescence intensity imaging system was developed based on the combined probe for the early diagnoses of atherosclerosis. This system is capable of real-time data acquisition and processing as well as image display. For flu...

  13. Edema macular quístico pseudofáquico: Detección mediante «optical coherence tomography» / Pseudophakic cystoid macular edema: Assesment with optical coherence tomography

    Scientific Electronic Library Online (English)

    C., Torrón-Fernández-Blanco; O., Ruiz-Moreno; E., Ferrer-Novella; A., Sánchez-Cano; F.M., Honrubia-López.

    2006-03-01

    Full Text Available SciELO Spain | Language: Spanish Abstract in spanish Objetivo: Detectar la incidencia de edema macular quístico (EMQ) tras cirugía de catarata tanto clínico como subclínico, mediante «ocular coherence tomography» (OCT) y comparar dicha incidencia entre un grupo de pacientes diabéticos y otro de no diabéticos. Material y métodos: Estudio prospectivo de [...] 260 ojos intervenidos de forma consecutiva de catarata mediante facoemulsificación con implante de lente intraocular acrílica, desde septiembre de 2004 a marzo de 2005. Grupo A: 208 ojos de pacientes no diabéticos, grupo B: 42 ojos de pacientes diabéticos, grupo C: 10 ojos de pacientes diabéticos con edema macular y que recibieron triamcinolona intravítrea (TAIV) al finalizar la cirugía. En cada revisión efectuada a los 6 días (basal), 5 semanas y 12 semanas se realizó biomicroscopía de polo posterior y OCT. Resultados: El espesor macular en la OCT, fue significativamente superior en el grupo B que en el grupo A (241,6 versus 204,6 µm p- 43,74 µm (2 DE del valor basal del grupo A). En el grupo B, seis ojos presentaron EMQ clínicamente significativo, con disminución de agudeza visual (14,2%), en 12 ojos detectamos aumento del espesor macular (28,5%). Las diferencias entre grupos fueron significativas (p Abstract in english Purpose: To determine the incidence of cystoid macular edema (CME) by means of clinical evaluation and subclinical assessment by means of ocular coherence tomography (OCT), and to compare the incidence between diabetic and non-diabetic groups of patients. Methods: Prospective study of 260 consecutiv [...] e cataract surgeries operated from September 2004 to March 2005. The procedures were performed by means of phacoemulsification plus intraocular acrylic lens implantation. Group A: 208 eyes of non-diabetic patients; Group B: 42 eyes of patients with diabetes and Group C: 10 eyes of diabetic patients with macular edema that received an intravitreal injection of triamcinolone at the end of surgery. Postoperative follow-up visits were performed 6 days (basal visit), 5 weeks and 12 weeks after surgery. Each visit included posterior pole biomicroscopy and OCT. Results: Central macular thickness measured by OCT was significantly increased in group B compared with group A (241.6 versus 204.6 µm; p

  14. Tomography approach for multi-object adaptive optics.

    Science.gov (United States)

    Vidal, Fabrice; Gendron, Eric; Rousset, Gérard

    2010-11-01

    Multi-object adaptive optics (MOAO) is a solution developed to perform a correction by adaptive optics (AO) in a science large field of view. As in many wide-field AO schemes, a tomographic reconstruction of the turbulence volume is required in order to compute the MOAO corrections to be applied in the dedicated directions of the observed very faint targets. The specificity of MOAO is the open-loop control of the deformable mirrors by a number of wavefront sensors (WFSs) that are coupled to bright guide stars in different directions. MOAO calls for new procedures both for the cross registration of all the channels and for the computation of the tomographic reconstructor. We propose a new approach, called "Learn and Apply (L&A)", that allows us to retrieve the tomographic reconstructor using the on-sky wavefront measurements from an MOAO instrument. This method is also used to calibrate the registrations between the off-axis wavefront sensors and the deformable mirrors placed in the science optical paths. We propose a procedure linking the WFSs in the different directions and measuring directly on-sky the required covariance matrices needed for the reconstructor. We present the theoretical expressions of the turbulence spatial covariance of wavefront slopes allowing one to derive any turbulent covariance matrix between two wavefront sensors. Finally, we discuss the convergence issue on the measured covariance matrices, we propose the fitting of the data based on the theoretical slope covariance using a reduced number of turbulence parameters, and we present the computation of a fully modeled reconstructor. PMID:21045886

  15. Breast tumor hypoxia mapping using ultrasound guided diffuse optical tomography

    Science.gov (United States)

    Biswal, Nrusingh C.; Xu, Yan; Zhu, Quing

    2011-02-01

    Tumor hypoxia is an important indicator of tumor metabolism and tumor response to various forms of therapy. Currently, no imaging modality exists that can directly map tumor hypoxia non-invasively. We present an ultrasound guided diffuse optical imaging technique for precisely measuring the tumor oxygenation. The approach employs ultrasound structural information as a-prior knowledge for diffuse optical imaging. Hypoxia mapping is achieved using endogenous chromophores such as oxy- and deoxy- hemoglobin in the tissue. Because oxy- and deoxy- hemoglobin respond differently at different wavelengths, four different laser diodes of wavelengths 740 nm, 780 nm, 808 nm and 830 nm were used for mapping tumor hypoxia by diffuse optical imaging. Hypoxia model experiments were performed using phantoms at different oxygenation conditions (Hemoglobin oxygen saturation: 14%-92%) representing the hemoglobin oxygenation range in tissue. Targets of different sizes mimicking different development stages of breast tumors, 1.0 cm to 2.5 cm diameter in 0.5 cm steps, were tested to validate the oxygen saturation measurement accuracy with target size. The absolute deviations between the estimated hemoglobin oxygen saturations from absorption maps and oxygen measurements obtained using a pO2 electrode were less than 8% over the measured range of oxygen saturations (14% - 92%). An inhomogeneous cocentric blood phantom of deoxygenated center core and oxygenated outer shell was imaged and deoxy- and oxy- hemoglobin maps revealed corresponding distributions which correlate with inhomogeneous deoxy- and oxy- distributions frequently seen in advanced breast cancers located in the depth range of 1-3 cm.

  16. All-optical tomography of electron spins in (In,Ga)As quantum dots

    Science.gov (United States)

    Varwig, S.; René, A.; Economou, Sophia E.; Greilich, A.; Yakovlev, D. R.; Reuter, D.; Wieck, A. D.; Reinecke, T. L.; Bayer, M.

    2014-02-01

    We demonstrate the basic features of an all-optical spin tomography on picosecond time scale. The magnetization vector associated with a mode-locked electron spin ensemble in singly charged quantum dots is traced by ellipticity measurements using picosecond laser pulses. After optical orientation the spins precess about a perpendicular magnetic field. By comparing the dynamics of two interacting ensembles with the dynamics of a single ensemble we find buildup of a spin component along the magnetic field in the two-ensemble case. This component arises from a Heisenberg-like spin-spin interaction.

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

    OpenAIRE

    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. This paper demonstrates the use of SD-OCT in a simulated roll-to-roll (R2R) process through monitoring some structural properties of moving screen printed interdigitated electrodes. It is shown that structural properties can be resolved for speeds up to ...

  18. Acousto-optical coherence tomography with a digital holographic detection scheme

    CERN Document Server

    Gross, Michel; Benoit, Emilie; Bossy, Emmanuel; Farahi, Salma; 10.1364/OL.37.003216

    2012-01-01

    Acousto-optical coherence tomography (AOCT) consists in using random phase jumps on ultrasound and light to achieve a millimeter resolution when imaging thick scattering media. We combined this technique with heterodyne off-axis digital holography. Two-dimensional images of absorbing objects embedded in scattering phantoms are obtained with a good signal-to-noise ratio. We study the impact of the phase modulation characteristics on the amplitude of the acousto-optic signal and on the contrast and apparent size of the absorbing inclusion.

  19. An all-at-once reduced Hessian SQP algorithm for frequency domain optical tomography

    Science.gov (United States)

    Kim, Hyun Keol; Gu, Xuejun; Hielscher, Andreas H.

    2009-02-01

    We introduce in this work a PDE-constrained approach to optical tomography that makes use of an all-atonce reduced Hessian Sequential Quadratic Programming (rSQP) scheme. The proposed scheme treats the forward and inverse variables independently, which makes it possible to update the radiation intensities and the optical coefficients simultaneously by solving the forward and inverse problems, all at once. We evaluate the performance of the proposed scheme with numerical and experimental data, and find that the rSQP scheme can reduce the computation time by a factor of 10 to 25, as compared to the commonly employed limited memory BFGS method.

  20. Using late arriving photons for diffuse optical tomography of biological objects

    International Nuclear Information System (INIS)

    The issues of detecting the inhomogeneities are studied aimed at mapping the distribution of absorption and scattering in soft tissues. A modification of the method of diffuse optical tomography is proposed for detecting directly and determining the region of spatial localisation of such absorbing and scattering inhomogeneities as a cyst, a hematoma, a tumour, as well as for measuring the degree of oxygenation or deoxygenation of blood, in which the late arriving photons that diffuse through the scattering object are used. (optical technologies in biophysics and medicine)