WorldWideScience

Sample records for saggital optical tomography

  1. Optical tomography in medicine

    Science.gov (United States)

    Domanski, Andrzej W.

    2001-07-01

    Optical imaging and spectroscopy of objects inside high scattering medium by use of light instead of X-rays are named an optical tomography. The optical tomography applied for medical diagnose seems to be very promising due to low risk of genetic changes inside living cells during visible and infrared photon treatments of tissue in contradiction to the X-ray examinations. The aim of the paper is to present short an overview of different kinds of the medical optical tomography. The main attention is done for current problems of the medical optical tomography. Some results of clinical tests of an optoelectronic mammoscope based on two wavelength transiluminance method for breast cancer imaging are presented as well.

  2. Optical coherence tomography

    International Nuclear Information System (INIS)

    The basic principles and possibilities of optical coherence tomography (OCT) as a method for the investigation of pathologies in medical diagnostics are outlined. We discuss the OCT method limitations and issues related to the need for improving the resolution of optical tomographs. The prospects are considered for developing the OCT methods based on probing with diffraction-free light beams. (authors)

  3. Dental optical coherence tomography.

    Science.gov (United States)

    Hsieh, Yao-Sheng; Ho, Yi-Ching; Lee, Shyh-Yuan; Chuang, Ching-Cheng; Tsai, Jui-che; Lin, Kun-Feng; Sun, Chia-Wei

    2013-01-01

    This review paper describes the applications of dental optical coherence tomography (OCT) in oral tissue images, caries, periodontal disease and oral cancer. The background of OCT, including basic theory, system setup, light sources, spatial resolution and system limitations, is provided. The comparisons between OCT and other clinical oral diagnostic methods are also discussed. PMID:23857261

  4. Dental Optical Coherence Tomography

    Directory of Open Access Journals (Sweden)

    Kun-Feng Lin

    2013-07-01

    Full Text Available This review paper describes the applications of dental optical coherence tomography (OCT in oral tissue images, caries, periodontal disease and oral cancer. The background of OCT, including basic theory, system setup, light sources, spatial resolution and system limitations, is provided. The comparisons between OCT and other clinical oral diagnostic methods are also discussed.

  5. Dental Optical Coherence Tomography

    OpenAIRE

    Kun-Feng Lin; Jui-che Tsai; Ching-Cheng Chuang; Shyh-Yuan Lee; Yi-Ching Ho; Yao-Sheng Hsieh; Chia-Wei Sun

    2013-01-01

    This review paper describes the applications of dental optical coherence tomography (OCT) in oral tissue images, caries, periodontal disease and oral cancer. The background of OCT, including basic theory, system setup, light sources, spatial resolution and system limitations, is provided. The comparisons between OCT and other clinical oral diagnostic methods are also discussed.

  6. Optical Tomography in Combustion

    DEFF Research Database (Denmark)

    Evseev, Vadim

    2013-01-01

    The new methodology of optical infrared tomography of flames and hot gas flows was developed in the PhD project with a view to future industrial applications. In particular, the methodology for the tomographic reconstruction of an axisymmetric lab flame temperature profile was developed and tested in the lab using Fourier transform infrared spectroscopy techniques, including a new tomographic measurement scheme, sweeping scanning, having great potential for industrial applications with limited optical access. The results were compared to the reference point measurements on the same flame and the deviations are discussed. The methods are shown to have promising potential for future industrial applications. The new multichannel infrared spectrometer system as a first prototype of the infrared spectroscopic tomography system was developed in the PhD project for simultaneous fast transient infrared spectral measurements at several line-of-sights with a view to applications for tomographic measurements on full-scale industrial combustion systems. The system was successfully applied on industrial scale for simultaneous fast exhaust gas temperature measurements in the three optical ports of the exhaust duct of the large Diesel engine. The results were compared to the measurements performed by another system employing spectral properties of nitric oxides in the ultraviolet range. A good agreement was observed between the results obtained using the two different systems. In the context of the PhD project, it was also important to investigate the spectral properties of major combustion species such as carbon dioxide and carbon monoxide in the infrared range at high temperatures to provide the theoretical background for the development of the optical tomography methods. The new software was developed for the line-by-line calculations of the transmission spectra of a carbon dioxide/carbon monoxide mixture which is able to use within reasonable time the most recent but huge CDSD-4000 database containing updated high-temperature spectroscopic line-by-line data. The software was used for the line-by-line calculations of the transmission spectra of the carbon dioxide/carbon monoxide mixture at high temperatures and the results were compared to the measurements in the high-temperature flow gas cell carried out before the PhD project. The results and discussion are presented in a journal article [Evseev et al. JQSRT 113 (2012) 2222, 10.1016/j.jqsrt.2012.07.015] included in the PhD thesis as an attachment. The knowledge and experience gained in the PhD project is the first important step towards introducing the advanced optical tomography methods of combustion diagnostics developed in the project to future industrial applications.

  7. Amplified Dispersive Optical Tomography

    CERN Document Server

    Goda, Keisuke; Jalali, Bahram

    2008-01-01

    Optical coherence tomography (OCT) has proven to be a powerful technique for studying tissue morphology in ophthalmology, cardiology, and endomicroscopy. Its performance is limited by the fundamental trade-off between the imaging sensitivity and acquisition speed -- a predicament common in virtually all imaging systems. In this paper, we circumvent this limit by using distributed Raman post-amplification of the reflection from the sample. We combine the amplification with simultaneously performed dispersive Fourier transformation, a process that maps the optical spectrum into an easily measured time-domain waveform. The Raman amplification enables measurement of weak signals which are otherwise buried in noise. It extends the depth range without sacrificing the acquisition speed or causing damage to the sample. As proof of concept, single-shot imaging with 15 dB improvement in sensitivity at an axial scan rate of 36.6 MHz is demonstrated.

  8. Quantum optical coherence tomography

    Science.gov (United States)

    Nasr, Magued Boshra

    Optical coherence tomography (OCT) has become a versatile and useful biological imaging technique. It is an interferometric scheme that makes use of a light source of short coherence time (broad spectrum) to carry out axial sectioning of a specimen. A particular merit that sets OCT apart from other optical-sectioning techniques, such as confocal and two-photon microscopy, is the decoupling of the axial resolution from the lateral resolution. In microscopy both resolutions, axial and lateral, depend on the numerical aperture (NA) of the lenses and the wavelength of the light used. The axial resolution of OCT is limited by the coherence length of the light source. Thus OCT can maintain high axial resolution at depth where high lateral resolution is not achievable. The axial resolution of OCT is enhanced by increasing the spectral bandwidth of the source. However, as the bandwidth is increased the effects of group-velocity dispersion (GVD) become increasingly deleterious. In this work, we introduce a quantum version of OCT, quantum optical coherence tomography (QOCT), that makes use of an entangled twin-photon light source. A particular merit of QOCT is that it is inherently immune to the GVD effects of the medium by virtue of the frequency entanglement associated with the twin-photon pairs. For sources of the same bandwidth, the entangled nature of the twin photons provides a factor of two enhancement in resolution relative to OCT. Moreover, QOCT permits us to directly determine the GVD coefficients of the interstitial media between the reflecting surfaces of the sample, a measurement that is not directly accessible in regular OCT. In this Ph.D. work we have developed the theory for the QOCT technique and carried out many experiments that demonstrate the above-mentioned advantages of QOCT over OCT. The axial resolution of QOCT is governed by the bandwidth of the entangled twin-photon light source. The entangled twin photons may be conveniently generated via spontaneous parametric down-conversion (SPDC). In this process a monochromatic laser beam of angular frequency op, serving as the pump, is sent to a second-order nonlinear optical crystal (NLC). A fraction of the pump photons disintegrate into pairs of down-converted photons. In this work, we also present a method for generating an ultra-broadband spectrum of SPDC that is independent of the thickness of the nonlinear crystal, thereby yielding down-converted photons of high flux. We show that the bandwidth amplification inherent in the SPDC process is maximized at a wavelength where the group-velocity dispersion is minimal. Experimental results demonstrating the broad spectrum produced by this technique are presented.

  9. 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.

  10. 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.

  11. Increasing stability for optical tomography

    OpenAIRE

    Lai, Ru-yu

    2013-01-01

    We study the phenomenon of increasing stability in the diffuse optical tomography (DOT). It is well-known that the DOT inverse problem is exponentially ill-posed. In this paper, we show that the ill-posedness decreases when we increase the frequency.

  12. 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...

  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. 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.

  15. 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

  16. 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

  17. 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

  18. Optical Coherence Tomography in Glaucoma

    Science.gov (United States)

    Berisha, Fatmire; Hoffmann, Esther M.; Pfeiffer, Norbert

    Retinal nerve fiber layer (RNFL) thinning and optic nerve head cupping are key diagnostic features of glaucomatous optic neuropathy. The higher resolution of the recently introduced SD-OCT offers enhanced visualization and improved segmentation of the retinal layers, providing a higher accuracy in identification of subtle changes of the optic disc and RNFL thinning associated with glaucoma.

  19. Optical coherence tomography. Development, principles, applications

    Energy Technology Data Exchange (ETDEWEB)

    Fercher, Adolf Friedrich [Medizinische Univ. Wien, Vienna (Austria). ZBMTP - Medizinische Physik

    2010-07-01

    This paper presents a review of the development of optical coherence tomography (OCT), its principles and important applications. Basic OCT systems are described and the physical foundations of OCT signal properties and signal recording systems are reviewed. Recent examples of OCT applications in ophthalmology, cardiology, gastroenterology and dermatology outline the relevance of this advanced imaging modality in the medical field. (orig.)

  20. 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)

  1. Time-resolved transillumination and optical tomography

    Science.gov (United States)

    de Haller, Emmanuel B.

    1996-01-01

    In response to an invitation by the editor-in-chief, I would like to present the current status of time-domain imaging. With exciting new photon diffusion techniques being developed in the frequency domain and promising optical coherence tomography, time-resolved transillumination is in constant evolution and the subject of passionate discussions during the numerous conferences dedicated to this subject. The purpose of time-resolved optical tomography is to provide noninvasive, high-resolution imaging of the interior of living bodies by the use of nonionizing radiation. Moreover, the use of visible to near-infrared wavelength yields metabolic information. Breast cancer screening is the primary potential application for time-resolved imaging. Neurology and tissue characterization are also possible fields of applications. Time- resolved transillumination and optical tomography should not only improve diagnoses, but the welfare of the patient. As no overview of this technique has yet been presented to my knowledge, this paper briefly describes the various methods enabling time-resolved transillumination and optical tomography. The advantages and disadvantages of these methods, as well as the clinical challenges they face are discussed. Although an analytic and computable model of light transport through tissues is essential for a meaningful interpretation of the transillumination process, this paper will not dwell on the mathematics of photon propagation.

  2. Optical coherence tomography in conjunction with bronchoscopy

    International Nuclear Information System (INIS)

    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)al histology. (author)

  3. 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...

  4. Computerised tomography in calcified optic nerve drusen

    International Nuclear Information System (INIS)

    Drusen (astrocytic hamartoma) of the optic nerve are a rare eye disease produced by ocular calcification (inclusions containing calcium) at the optic disc surface. These drusen can lead to eye complaints as they grow bigger; in particular, they can cause loss of vision and can also limit the visual field. Ophthalmologically, they are characterised by an indistinct optic disc and/or ectasia of the optic disc which is sometimes combined with a poorly defined optic disc margin. Differential diagnosis must take into consideration the presence of space-occupying intracranial processes. The final diagnosis can be made via computerised tomography on the basis of a characteristic calcification pattern. Hence, the radiologist must be familiar with the disease pattern and must be able to differentiate this against other types of intraocular calcifications. (orig.)

  5. Enhanced depth imaging optical coherence tomography.

    Science.gov (United States)

    Wong, Ian Y; Koizumi, Hideki; Lai, Wico W

    2011-07-01

    Imaging the choroid with conventional commercial spectral-domain optical coherence tomography (SD-OCT) has been difficult, mainly because of difficulty in signal transmission beyond the retinal pigment epithelium. A recent modification to the standard technique, termed enhanced depth imaging optical coherence tomography (EDI-OCT), was able to image the choroid with reasonable clarity using commercial SD-OCTs. The aim of this article was to review the technique, principle, recent findings, and possible future developments regarding EDI-OCT. A MEDLINE search on all published articles on EDI-OCT was performed up to December 2010. The principle behind EDI-OCT was discussed. Modification to the conventional technique in image acquisition was described and illustrated with figures. EDI-OCT findings in various retinal and choroidal diseases were discussed. Advantages and disadvantages were also discussed. EDI-OCT has proved to be a promising novel technique in imaging the choroid. PMID:21790115

  6. 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.

  7. Optical homodyne tomography with polynomial series expansion

    OpenAIRE

    Benichi, Hugo; Furusawa, Akira

    2011-01-01

    We present and demonstrate a method for optical homodyne tomography based on the inverse Radon transform. Different from the usual filtered back-projection algorithm, this method uses an appropriate polynomial series to expand the Wigner function and the marginal distribution and discretize Fourier space. We show that this technique solves most technical difficulties encountered with kernel deconvolution based methods and reconstructs overall better and smoother Wigner funct...

  8. Near-Infrared Diffuse Optical Tomography

    OpenAIRE

    Hielscher, A. H.; Bluestone, A. Y.; Abdoulaev, G. S.; Klose, A. D.; Lasker, J.; Stewart, M.; Netz, U.; Beuthan, J.

    2002-01-01

    Diffuse optical tomography (DOT) is emerging as a viable new biomedical imaging modality. Using near-infrared (NIR) light, this technique probes absorption as well as scattering properties of biological tissues. First commercial instruments are now available that allow users to obtain cross-sectional and volumetric views of various body parts. Currently, the main applications are brain, breast, limb, joint, and fluorescence/bioluminescence imaging. Although the spatial resolution is limited w...

  9. 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...

  10. 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.

  11. Nanoscale optical tomography with cathodoluminescence spectroscopy

    Science.gov (United States)

    Atre, Ashwin C.; Brenny, Benjamin J. M.; Coenen, Toon; García-Etxarri, Aitzol; Polman, Albert; Dionne, Jennifer A.

    2015-05-01

    Tomography has enabled the characterization of the Earth's interior, visualization of the inner workings of the human brain, and three-dimensional reconstruction of matter at the atomic scale. However, tomographic techniques that rely on optical excitation or detection are generally limited in their resolution by diffraction. Here, we introduce a tomographic technique—cathodoluminescence spectroscopic tomography—to probe optical properties in three dimensions with nanometre-scale spatial and spectral resolution. We first obtain two-dimensional cathodoluminescence maps of a three-dimensional nanostructure at various orientations. We then use the method of filtered back-projection to reconstruct the cathodoluminescence intensity at each wavelength. The resulting tomograms allow us to locate regions of efficient cathodoluminescence in three dimensions across visible and near-infrared wavelengths, with contributions from material luminescence and radiative decay of electromagnetic eigenmodes. The experimental signal can be further correlated with the radiative local density of optical states in particular regions of the reconstruction. We demonstrate how cathodoluminescence tomography can be used to achieve nanoscale three-dimensional visualization of light–matter interactions by reconstructing a three-dimensional metal–dielectric nanoresonator.

  12. Turbidity Measurement Using An Optical Tomography System

    OpenAIRE

    Sallehuddin Bin Ibrahim

    2013-01-01

    Turbidity is used to describe water quality and it can be caused by the presence of suspended particles and organic matter such as algae, clay and silt. The measurement of turbidity level of water is vital to domestic water supplies since it is related to public health and water treatment process. This paper presents an investigation on an optical tomography system to estimate the turbidity level in a sample of water. The optical sensors consist of infrared light-emitting diodes (LED) as tran...

  13. Optical coherence tomography technology and applications

    CERN Document Server

    Fujimoto, James

    2015-01-01

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

  14. 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.

  15. 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

  16. Optical homodyne tomography with polynomial series expansion

    International Nuclear Information System (INIS)

    We present and demonstrate a method for optical homodyne tomography based on the inverse Radon transform. Different from the usual filtered back-projection algorithm, this method uses an appropriate polynomial series to expand the Wigner function and the marginal distribution, and discretize Fourier space. We show that this technique solves most technical difficulties encountered with kernel deconvolution-based methods and reconstructs overall better and smoother Wigner functions. We also give estimators of the reconstruction errors for both methods and show improvement in noise handling properties and resilience to statistical errors.

  17. In vivo cellular visualization of the human retina using optical coherence tomography and adaptive optics

    Energy Technology Data Exchange (ETDEWEB)

    Olivier, S S; Jones, S M; Chen, D C; Zawadzki, R J; Choi, S S; Laut, S P; Werner, J S

    2006-01-05

    Optical coherence tomography (OCT) sees the human retina sharply with adaptive optics. In vivo cellular visualization of the human retina at micrometer-scale resolution is possible by enhancing Fourier-domain optical-coherence tomography with adaptive optics, which compensate for the eye's optical aberrations.

  18. 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.

  19. 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

  20. 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.

  1. Near-infrared diffuse optical tomography.

    Science.gov (United States)

    Hielscher, A H; Bluestone, A Y; Abdoulaev, G S; Klose, A D; Lasker, J; Stewart, M; Netz, U; Beuthan, J

    2002-01-01

    Diffuse optical tomography (DOT) is emerging as a viable new biomedical imaging modality. Using near-infrared (NIR) light, this technique probes absorption as well as scattering properties of biological tissues. First commercial instruments are now available that allow users to obtain cross-sectional and volumetric views of various body parts. Currently, the main applications are brain, breast, limb, joint, and fluorescence/bioluminescence imaging. Although the spatial resolution is limited when compared with other imaging modalities, such as magnetic resonance imaging (MRI) or X-ray computerized tomography (CT), DOT provides access to a variety of physiological parameters that otherwise are not accessible, including sub-second imaging of hemodynamics and other fast-changing processes. Furthermore, DOT can be realized in compact, portable instrumentation that allows for bedside monitoring at relatively low cost. In this paper, we present an overview of current state-of-the -art technology, including hardware and image-reconstruction algorithms, and focus on applications in brain and joint imaging. In addition, we present recent results of work on optical tomographic imaging in small animals. PMID:14646043

  2. 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

  3. Advanced modelling of optical coherence tomography systems

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, Peter E [Optics and Plasma Research Department, Risoe National Laboratory, Building 128, PO Box 49, DK-4000 Roskilde (Denmark); Thrane, Lars [Optics and Plasma Research Department, Risoe National Laboratory, Building 128, PO Box 49, DK-4000 Roskilde (Denmark); Yura, Harold T [Electronics and Photonics Laboratory, The Aerospace Corporation, PO Box 92957, Los Angeles, CA 90009 (United States); Tycho, Andreas [Optics and Plasma Research Department, Risoe National Laboratory, Building 128, PO Box 49, DK-4000 Roskilde (Denmark); Joergensen, Thomas M [Optics and Plasma Research Department, Risoe National Laboratory, Building 128, PO Box 49, DK-4000 Roskilde (Denmark); Frosz, Michael H [Optics and Plasma Research Department, Risoe National Laboratory, Building 128, PO Box 49, DK-4000 Roskilde (Denmark)

    2004-04-07

    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 reviewed. An advanced Monte Carlo model for calculating the OCT signal is also reviewed, and the validity of this model is shown through a mathematical proof based on the extended Huygens-Fresnel principle. Moreover, for the first time the model is verified experimentally. 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. For the first time, the algorithm is demonstrated by using the Monte Carlo model as a numerical tissue phantom. Such algorithm holds promise for improving OCT imagery and to extend the possibility for functional imaging.

  4. Optical Coherence Tomography for Tracking Canvas Deformation

    International Nuclear Information System (INIS)

    Preliminary results of the application of optical coherence tomography (OCT), in particular in its spectral mode (SOCT), to tracking of deformations in paintings on canvas caused by periodical humidity changes are presented. The setup is able to monitor the position of a chosen point at the surface of a painting with micrometre precision, simultaneously in three dimensions, every 100 seconds. This allows recording of deformations associated with crack formation. For the particular painting model examined, it was shown that the surface moves in-plane towards the corner, and bulges outwards (Z-direction) in response to a rise in humidity. Subsequent to the first humidification/drying cycle, translation in the Z-direction is decreased, whilst in-plane translations increase somewhat. It was also shown that the response of the painting on canvas begins immediately on changing the relative humidity in the surroundings.

  5. Computed tomography in orbital fractures and optic nerve trauma

    International Nuclear Information System (INIS)

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

  6. Intraoperative spectral domain optical coherence tomography for vitreoretinal surgery

    OpenAIRE

    Tao, Yuankai K.; Justis P. Ehlers; TOTH, CYNTHIA A.; Izatt, Joseph A.

    2010-01-01

    We demonstrate in vivo human retinal imaging using an intraoperative microscope-mounted optical coherence tomography system (MMOCT). Our optomechanical design adapts an Oculus Binocular Indirect Ophthalmo Microscope (BIOM3), suspended from a Leica ophthalmic surgical microscope, with spectral domain optical coherence tomography (SD-OCT) scanning and relay optics. The MMOCT enables wide-field noncontact real-time cross-sectional imaging of retinal structure, allowing for SD-OCT augmented intra...

  7. 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...

  8. 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

  9. Optical coherence tomography analysis of axonal loss in band atrophy of the optic nerve

    OpenAIRE

    Monteiro, M L R; Leal, B C; Rosa, A A M; Bronstein, M D

    2004-01-01

    Aims: To measure axonal loss in patients with band atrophy of the optic nerve caused by optic chiasm compression using optical coherence tomography and to evaluate its ability in identifying this pattern of retinal nerve fibre layer (RNFL) loss.

  10. Optical coherence tomography for endodontic imaging

    Science.gov (United States)

    van Soest, G.; Shemesh, H.; Wu, M.-K.; van der Sluis, L. W. M.; Wesselink, P. R.

    2008-02-01

    In root canal therapy, complications frequently arise as a result of root fracture or imperfect cleaning of fins and invaginations. To date, there is no imaging method for nondestructive in vivo evaluation of the condition of the root canal, during or after treatment. There is a clinical need for a technique to detect defects before they give rise to complications. In this study we evaluate the ability of optical coherence tomography (OCT) to image root canal walls, and its capacity to identify complicating factors in root canal treatment. While the potential of OCT to identify caries has been explored before, endodontic imaging has not been reported. We imaged extracted lower front teeth after endodontic preparation and correlated these images to histological sections. A 3D OCT pullback scan was made with an endoscopic rotating optical fiber probe inside the root canal. All oval canals, uncleaned fins, risk zones, and one perforation that were detected by histology were also imaged by OCT. As an example of an area where OCT has clinical potential, we present a study of vertical root fracture identification with OCT.

  11. Functional optical coherence tomography: principles and progress.

    Science.gov (United States)

    Kim, Jina; Brown, William; Maher, Jason R; Levinson, Howard; Wax, Adam

    2015-05-21

    In the past decade, several functional extensions of optical coherence tomography (OCT) have emerged, and this review highlights key advances in instrumentation, theoretical analysis, signal processing and clinical application of these extensions. We review five principal extensions: Doppler OCT (DOCT), polarization-sensitive OCT (PS-OCT), optical coherence elastography (OCE), spectroscopic OCT (SOCT), and molecular imaging OCT. The former three have been further developed with studies in both ex vivo and in vivo human tissues. This review emphasizes the newer techniques of SOCT and molecular imaging OCT, which show excellent potential for clinical application but have yet to be well reviewed in the literature. SOCT elucidates tissue characteristics, such as oxygenation and carcinogenesis, by detecting wavelength-dependent absorption and scattering of light in tissues. While SOCT measures endogenous biochemical distributions, molecular imaging OCT detects exogenous molecular contrast agents. These newer advances in functional OCT broaden the potential clinical application of OCT by providing novel ways to understand tissue activity that cannot be accomplished by other current imaging methodologies. PMID:25951836

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

    OpenAIRE

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

    2014-01-01

    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 ...

  13. 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

  14. Computed tomography of sarcoidosis of the optic nerve

    International Nuclear Information System (INIS)

    Two patients with optic nerve sarcoidosis, one proven by an open biopsy of the optic nerve, the other by clinical evidence of sarcoidosis and a positive conjunctival biopsy, were examined by computed tomography. In both cases increased diameter and pathological enhancement of the involved optic nerves were demonstrated. (orig.)

  15. Three-Dimensional Optical Coherence Tomography (3D OCT) Project

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

  16. Weighted filtered backprojection for quantitative fluorescence optical projection tomography.

    OpenAIRE

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

    2008-01-01

    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 pu...

  17. 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.

  18. Optical clearing of unsectioned specimens for three-dimensional imaging via optical transmission and emission tomography

    OpenAIRE

    Oldham, Mark; Sakhalkar, Harshad; Oliver, Tim; Johnson, G Allan; Dewhirst, Mark

    2008-01-01

    Optical computed tomography (optical-CT) and optical emission computed tomography (optical-ECT) are new techniques that enable unprecedented high-resolution 3-D multimodal imaging of tissue structure and function. Applications include imaging macroscopic gene expression and microvasculature structure in unsectioned biological specimens up to 8 cm3. A key requisite for these imaging techniques is effective sample preparation including optical clearing, which enables light transport through the...

  19. Optical coherence tomography and Doppler optical coherence tomography in the gastrointestinal tract

    Directory of Open Access Journals (Sweden)

    Eugen Osiac, Adrian S?ftoiu, Dan Ionut Gheonea, Ion Mandrila, Radu Angelescu

    2011-01-01

    Full Text Available Optical coherence tomography (OCT is a noninvasive, high-resolution, high-potential imaging method that has recently been introduced into medical investigations. A growing number of studies have used this technique in the field of gastroenterology in order to assist classical analyses. Lately, 3D-imaging and Doppler capabilities have been developed in different configurations, which make this type of investigation more attractive. This paper reviews the principles and characteristics of OCT and Doppler-OCT in connection with analyses of the detection of normal and pathological structures, and with the possibility to investigate angiogenesis in the gastrointestinal tract.

  20. Optical coherence tomography and Doppler optical coherence tomography in the gastrointestinal tract.

    Science.gov (United States)

    Osiac, Eugen; S?ftoiu, Adrian; Gheonea, Dan Ionut; Mandrila, Ion; Angelescu, Radu

    2011-01-01

    Optical coherence tomography (OCT) is a noninvasive, high-resolution, high-potential imaging method that has recently been introduced into medical investigations. A growing number of studies have used this technique in the field of gastroenterology in order to assist classical analyses. Lately, 3D-imaging and Doppler capabilities have been developed in different configurations, which make this type of investigation more attractive. This paper reviews the principles and characteristics of OCT and Doppler-OCT in connection with analyses of the detection of normal and pathological structures, and with the possibility to investigate angiogenesis in the gastrointestinal tract. PMID:21218079

  1. Carious growth monitoring 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.

    2006-02-01

    Optical Coherence Tomography was used to monitor subsurface caries evolution process in vitro. Human tooth was used and bacteria were employed to induce caries lesions. Twenty-five human third molars, were used in this study. The teeth were cut longitudinally at mesio-distal direction; the surfaces were coated with nail varnish except for two squared windows (2x4 mm); at the cement-enamel junction. Artificial lesions were induced by a S. Mutans microbiological culture. The samples (N = 50) were divided into groups according to the demineralization time: 3, 5, 7, 9 and 11 days. The culture medium, was changed each 48 hours. After the demineralization process the samples were rinsed with double-deionized water and stored in a humid environment. The OCT system was implemented with average power of 96 ?W in the sample arm, providing a 23 ?m of axial resolution. The images were produced with lateral scans step of 10 ?m. The detection system was composed by a detector, a demodulator and a computer. With the images generated by OCT it was possible to determine the lesion depth as function of sample exposition time to microbiological culture. We observed that the depth of the lesion in the root dentine increased from 70 ?m to 230 ?m, depending of exposure time, and follows the bacterial population growth law. This OCT system accurately depicts hard dental tissue and it was able to detect early caries in its structure, providing a powerful contactless high resolution image of lesions.

  2. Polarization sensitive optical coherence tomography detection method

    International Nuclear Information System (INIS)

    This study demonstrates the potential of polarization sensitive optical coherence tomography (PS-OCT) for non-invasive in vivo detection and characterization of early, incipient caries lesions. PS-OCT generates cross-sectional images of biological tissue while measuring the effect of the tissue on the polarization state of incident light. Clear discrimination between regions of normal and demineralized enamel is first shown in PS-OCT images of bovine enamel blocks containing well-characterized artificial lesions. High-resolution, cross-sectional images of extracted human teeth are then generated that clearly discriminate between the normal and carious regions on both the smooth and occlusal surfaces. Regions of the teeth that appeared to be demineralized in the PS-OCT images were verified using histological thin sections examined under polarized light microscopy. The PS-OCT system discriminates between normal and carious regions by measuring the polarization state of the back-scattered 1310 nm light, which is affected by the state of demineralization of the enamel. Demineralization of enamel increases the scattering coefficient, thus depolarizing the incident light. This study shows that PS-OCT has great potential for the detection, characterization, and monitoring of incipient caries lesions

  3. Polarization sensitive optical coherence tomography detection method

    Energy Technology Data Exchange (ETDEWEB)

    Everett, M J; Sathyam, U S; Colston, B W; DaSilva, L B; Fried, D; Ragadio, J N; Featherstone, J D B

    1999-05-12

    This study demonstrates the potential of polarization sensitive optical coherence tomography (PS-OCT) for non-invasive in vivo detection and characterization of early, incipient caries lesions. PS-OCT generates cross-sectional images of biological tissue while measuring the effect of the tissue on the polarization state of incident light. Clear discrimination between regions of normal and demineralized enamel is first shown in PS-OCT images of bovine enamel blocks containing well-characterized artificial lesions. High-resolution, cross-sectional images of extracted human teeth are then generated that clearly discriminate between the normal and carious regions on both the smooth and occlusal surfaces. Regions of the teeth that appeared to be demineralized in the PS-OCT images were verified using histological thin sections examined under polarized light microscopy. The PS-OCT system discriminates between normal and carious regions by measuring the polarization state of the back-scattered 1310 nm light, which is affected by the state of demineralization of the enamel. Demineralization of enamel increases the scattereing coefficient, thus depolarizing the incident light. This study shows that PS-OCT has great potential for the detection, characterization, and monitoring of incipient caries lesions.

  4. Optical coherence tomography imaging of the optic nerve head pre optic and post optic nerve sheath fenestration.

    Science.gov (United States)

    Chowdhury, Haziq Raees; Rajak, Saul; Heath, Dominic; Brittain, Paul

    2015-01-01

    Idiopathic intracranial hypertension (IIH) is a disorder of unknown aetiology, and causes elevated intracranial pressures. This is often associated with papilloedema with subsequent degrees of optic atrophy if the intracranial pressures are not controlled in a timely manner. Optical coherence tomography imaging is widely recognised for its use in the monitoring of optic nerves in glaucoma, and this report is the first to describe its use to monitor the optic nerve head pre optic and post optic nerve sheath fenestration. PMID:26150609

  5. Clinical NIR spectroscopy and optical tomography of the testis

    Science.gov (United States)

    Hampel, Uwe; Schleicher, Eckhard; Zepnick, H.; Freyer, Richard

    2001-10-01

    Optical tomography and NIR spectroscopy are potential methods to improve the diagnosis of testicular pathologies. To evaluate the methods clinically we developed a special measurement device with the capability of spatially resolved laser spectroscopy and optical tomography of the testis. Simple spectroscopy is primarily used to obtain global tissue optical properties of the testis and to find correlations of optical parameters with type and stage of certain pathologies. Optical tomography is applied to visualize spectral contrasts in limited tissue volumes, such as tumors. In the course of the study we will determine whether NIR techniques posses the required specifity and sensitivity to give additional quantitative information about tissue perfusion parameters and to serve for a tumor differentiation.

  6. Optical coherence tomography of central serous chorioretinopathy

    Directory of Open Access Journals (Sweden)

    Feng Yan

    2013-06-01

    Full Text Available AIM:To observe the imaging features of the foveal photoreceptor layer in eyes with central serous chorioretinopathy(CSCusing frequency-domain optical coherence tomography(FD-OCTand to find the relationship between best-corrected visual acuity(BCVAand the morphology of thickness of the outer nuclear layer.METHODS: Totally 58 eyes from 54 CSC patients and 60 eyes from 30 healthy volunteers as the control group were selected. FD-OCT scan was performed on all the patients and volunteers. FD-OCT scan of 6mm horizontal line was performed, the scan depth was 1.9mm with a 5.8mm×5.8mm transverse area, the vertical and horizontal resolution was 5?m and 18?m respectively. The scan mode was 512×496. The morphological changes of FD-OCT on different stages of CSC were observed and the relationship between best-corrected visual acuity(BCVAand the morphology of thickness of the outer nuclear layer were analyzed.RESULTS: Simple serous neuroepithelial layer detachment and simple serous neuroepithelial layer detachment associated with pigment epithelial layer detachment at macula were about 84.5% of all the patients. Thickness of the outer nuclear layer was thinner from acute stage to chronic stage of CSC, and the relationship between thickness of the outer nuclear layer and BCVA was negative.CONCLUSION: FD-OCT can detect the detailed morphologic changes and pathological morphology at the foveal photoreceptor layer in eyes with CSC patients.

  7. 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.

  8. 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...

  9. Functional swept source optical coherence tomography

    International Nuclear Information System (INIS)

    Optical coherence tomography (OCT) is a non-invasive imaging modality capable of providing information about a sample structure along the three spatial dimensions with micrometer scale resolution. A new chapter opened with the development of functional OCT that provides additional information to the standard structural imaging. Among those extensions is Doppler OCT (D-OCT) that yields knowledge about the motion of the sample and/or its substructure. Its main application in biomedical imaging is the assessment of blood flow. D-OCT is therefore often associated with blood velocity measurement and recently with the visualization of the vascular network. Blood flow and vasculature are important markers of tissue health. Their assessment provides crucial information for diagnostics, treatment planning and monitoring. OCT is in a good position, as a non-invasive technique, to become an alternative to current fluorescence based techniques, allowing thereby also more frequent examination and broader screenings and, as a high resolution modality, to give insight into potential changes at the capillary level. An important challenge of in vivo imaging is patient motion that decreases the quality of acquisitions. One solution to that issue is high-speed imaging. Recently swept source OCT (SSOCT) revealed to be an efficient technology to achieve high-speed. This thesis investigates the use of swept sources for qualitative and quantitative vasculature imaging. It is presented via five journal papers that form its backbone. Prior to that, main concepts of FDOCT, D-OCT and SS systems are presented. The first paper reports a SSOCT system for skin imaging. In standard OCT systems, improving the lateral resolution comes at a cost of reduced depth of focus. This should be avoided in order to be able to assess different vascular beds in depth while keeping the speed advantage of FDOCT. Employing a Bessel beam for illumination of the sample allows circumventing this issue. The image quality of that configuration is compared to that of a standard system. Also, the further advantages of Bessel illumination, such as beam self-regeneration and dark-field imaging are demonstrated. The second paper demonstrates clinically relevant applications in dermatology. The system and the post-processing algorithms are applied to healthy and pathological skin, thereby exhibiting the potential of the system for clinical application. We demonstrate with selected examples that disease, including non-melanoma skin cancer, affects the vasculature network and its perfusion. It confirms the relevancy of providing additional functional information to the standard structure. The third paper applies similar post-processing to imaging of the posterior pole vasculature. This work demonstrates the need for speed in in vivo imaging and paves the way to future clinical procedures. Ultrahigh-speed allows imaging over a large field of view in a few seconds, hence, bypassing the need for volume stitching. Dedicated post-processing permits depth resolved visualization from large vessels to capillaries non-invasively. The fourth paper switches the topic to quantitative blood flow assessment by the introduction of a system allowing for stable blood flow velocity measurements. Employing two beams measuring the same location along different directions provides accurate velocity measurements. Still, this fixed optical illumination becomes unstable if the vessel is perpendicular to the illumination plane subtended by both directions. The publication suggests utilizing a Dove prism to rotate the illumination plane and thereby improving the flexibility of that configuration. Finally, the last paper proposes a method to optically resolve a photoacoustic signal with a SSOCT system. A combination of photoacoustics with OCT would provide complementary spectroscopic or metabolic information about the sample and would ultimately improve knowledge about tissue health.(author)

  10. Polarization-Sensitive Quantum Optical Coherence Tomography: Experiment

    OpenAIRE

    Booth, Mark C.; Saleh, Bahaa E. A.; Teich, Malvin Carl

    2010-01-01

    Polarization-sensitive quantum optical coherence tomography (PS-QOCT) makes use of a Type-II twin-photon light source for carrying out optical sectioning with polarization sensitivity. A BBO nonlinear optical crystal pumped by a Ti:sapphire psec-pulsed laser is used to confirm the theoretical underpinnings of this imaging paradigm. PS-QOCT offers even-order dispersion cancellation with simultaneous access to the group-velocity dispersion characteristics of the interstitial m...

  11. Accuracy of optical navigation systems for automatic head surgery: optical tracking versus optical coherence tomography

    Science.gov (United States)

    Díaz Díaz, Jesús; Riva, Mauro H.; Majdani, Omid; Ortmaier, Tobias

    2014-03-01

    The choice of a navigation system highly depends on the medical intervention and its accuracy demands. The most commonly used systems for image guided surgery (IGS) are based on optical and magnetic tracking systems. This paper compares two optical systems in terms of accuracy: state of the art triangulation-based optical tracking (OT) and optical coherence tomography (OCT). We use an experimental setup with a combined OCT and cutting laser, and an external OT. We simulate a robotic assisted surgical intervention, including planning, navigation, and processing, and compare the accuracies reached at a specific target with each navigation system.

  12. 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.

  13. 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.

  14. Shape-parameterized diffuse optical tomography holds promise for sensitivity enhancement of fluorescence molecular tomography.

    Science.gov (United States)

    Wu, Linhui; Wan, Wenbo; Wang, Xin; Zhou, Zhongxing; Li, Jiao; Zhang, Limin; Zhao, Huijuan; Gao, Feng

    2014-10-01

    A fundamental approach to enhancing the sensitivity of the fluorescence molecular tomography (FMT) is to incorporate diffuse optical tomography (DOT) to modify the light propagation modeling. However, the traditional voxel-based DOT has been involving a severely ill-posed inverse problem and cannot retrieve the optical property distributions with the acceptable quantitative accuracy and spatial resolution. Although, with the aid of an anatomical imaging modality, the structural-prior-based DOT method with either the hard- or soft-prior scheme holds promise for in vivo acquiring the optical background of tissues, the low robustness of the hard-prior scheme to the segmentation error and inferior performance of the soft-prior one in the quantitative accuracy limit its further application. We propose in this paper a shape-parameterized DOT method for not only effectively determining the regional optical properties but potentially achieving reasonable structural amelioration, lending itself to FMT for comparably improved recovery of fluorescence distribution. PMID:25360379

  15. Common path optical coherence tomography with fibre bundle probe

    OpenAIRE

    Han, J.-H.; X Liu; C. G. Song; 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...

  16. Artery phantoms for intravascular optical coherence tomography: healthy arteries

    OpenAIRE

    Bisaillon, Charles-Étienne; Dufour, Marc L.; Lamouche, Guy

    2011-01-01

    We present a method to make phantoms of coronary arteries for intravascular optical coherence tomography (IV-OCT). The phantoms provide a calibrated OCT response similar to the layered structure of arteries. The optical properties of each layer are achieved with specific concentrations of alumina and carbon black in a silicone matrix. This composition insures high durability and also approximates the elastic properties of arteries. The phantoms are fabricated in a tubular shape by the success...

  17. Late acquired stent malapposition detected by optical coherence tomography examination.

    Science.gov (United States)

    Bouki, Konstantina P; Chatzopoulos, Dionissios N; Katsafados, Mihail G; Elaiopoulos, Dimitrios A; Psychari, Stavroula N; Apostolou, Thomas S

    2009-11-12

    Late stent malapposition may play a role in stent thrombosis, but the results of several intravascular ultrasound and few optical coherence tomography (OCT) studies are still controversial. We present a case of late acquired stent malapposition after drug eluting stent implantation, identified by follow-up OCT examination at 12 months, which was not related with any adverse clinical event. PMID:19446897

  18. Optical coherence tomography and noninvasive blood glucose monitoring: a review

    Science.gov (United States)

    Larin, Kirill V.; Ashitkov, Taras V.; Larina, Irina V.; Petrova, Irina Y.; Eledrisi, Mohsen S.; Motamedi, Massoud; Esenaliev, Rinat O.

    2004-08-01

    Effective treatment and management of diabetic disease require frequent or continuous monitoring of blood glucose concentration. Currently used methods for monitoring of the blood glucose are invasive and, therefore, are not suitable for the frequent measurements. In this paper we review our recent results on development of Optical Coherence Tomography technique for noninvasive monitoring of glucose concentration in skin.

  19. Optical coherence tomography changes in macular CMV retinitis

    OpenAIRE

    Sun, Lisa L.; Goodwin, Todd; Park, Joseph J.

    2012-01-01

    Cytomegalovirus (CMV) retinitis characteristically causes peripheral retinitis with associated vasculitis. It rarely begins in the macula or causes macular necrosis exclusively. We report a case of unilateral macular CMV retinitis in a 65-year-old immunosuppressed patient and document changes in the macula during treatment through optical coherence tomography (OCT).

  20. 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.

  1. The use of optical coherence tomography in neurology.

    Science.gov (United States)

    Lamirel, Cédric; Newman, Nancy; Biousse, Valéerie

    2009-01-01

    Optical coherence tomography (OCT) is a noninvasive imaging technique routinely used in ophthalmology to visualize and quantify the layers of the retina. OCT allows direct visualization and measurement of the topography of the optic nerve head and retinal nerve fiber layer thickness in the peripapillary and macular regions with micron-scale resolution. These measurements are of particular interest in optic neuropathies and in numerous neurologic disorders in which there is axonal loss, such as multiple sclerosis. This article provides a detailed overview of OCT and its potential applications in neurology. PMID:20065921

  2. Polarization-Sensitive Quantum Optical Coherence Tomography: Experiment

    CERN Document Server

    Booth, Mark C; Teich, Malvin Carl

    2010-01-01

    Polarization-sensitive quantum optical coherence tomography (PS-QOCT) makes use of a Type-II twin-photon light source for carrying out optical sectioning with polarization sensitivity. A BBO nonlinear optical crystal pumped by a Ti:sapphire psec-pulsed laser is used to confirm the theoretical underpinnings of this imaging paradigm. PS-QOCT offers even-order dispersion cancellation with simultaneous access to the group-velocity dispersion characteristics of the interstitial medium between the reflecting surfaces of the sample.

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

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Chi; Wong, Kenneth K. Y., E-mail: kywong@eee.hku.hk [Photonic Systems Research Laboratory, Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam Road (Hong Kong)

    2014-09-01

    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.

  4. On the optical theory of photoelastic tomography.

    Science.gov (United States)

    Ainola, Leo; Aben, Hillar

    2004-06-01

    In recent years many authors have considered the possibility of using tomography for nondestructive determination of three-dimensional stress fields. A natural starting point for this is integrated photoelasticity. The problem is complicated since the stress field is a tensor field, and in the general case in integrated photoelasticity the relationships between the measurement data and the parameters of the stress field are non-linear. To elucidate these relationships, we have systematically studied the propagation of polarized light in an inhomogeneous birefringent medium. The inverse problem of integrated photoelasticity is formulated in the general form, and particular cases in which the polarization transformation matrix is exactly determined by integrals of the stress tensor components are considered. The possibility of using the Radon inversion for approximate determination of the normal stress field in an arbitrary section of the test object is outlined. PMID:15191193

  5. 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.

  6. Optical coherence tomography guided peeling of macular epiretinal membrane

    Directory of Open Access Journals (Sweden)

    Yoshio Hirano

    2010-12-01

    Full Text Available Yoshio Hirano, Tsutomu Yasukawa, Yuichiro OguraDepartment of Ophthalmology and Visual Science, Nagoya City University Graduate School of Medical Sciences, Nagoya, JapanAbstract: Optical coherence tomography (OCT has emerged as a powerful diagnostic aid in disorders of the vitreoretinal juncture. The purpose of this study is to determine whether OCT can be used as an additional tool for evaluating an architecture including the thickened area, and the identifiable edge of a macular epiretinal membrane (ERM, and helping us to dissect the ERM from the retinal surface more easily and safely. In two cases with ERM, the edges of the membranes were detected by OCT, and the peeling of the membrane was started at the area easily. OCT guided ERM peeling might be useful for dissecting ERM membranes without any hesitation.Keywords: optical coherence tomography, epiretinal membrane, vitrectomy

  7. Mesh Optimization for Monte Carlo-Based Optical Tomography

    Directory of Open Access Journals (Sweden)

    Andrew Edmans

    2015-04-01

    Full Text Available Mesh-based Monte Carlo techniques for optical imaging allow for accurate modeling of light propagation in complex biological tissues. Recently, they have been developed within an efficient computational framework to be used as a forward model in optical tomography. However, commonly employed adaptive mesh discretization techniques have not yet been implemented for Monte Carlo based tomography. Herein, we propose a methodology to optimize the mesh discretization and analytically rescale the associated Jacobian based on the characteristics of the forward model. We demonstrate that this method maintains the accuracy of the forward model even in the case of temporal data sets while allowing for significant coarsening or refinement of the mesh.

  8. Enhancement of fluorescence molecular tomography with structural-prior-based diffuse optical tomography: combating optical background uncertainty.

    Science.gov (United States)

    Wu, Linhui; Zhao, Huijuan; Wang, Xin; Yi, Xi; Chen, Weiting; Gao, Feng

    2014-10-20

    The common approach in fluorescence molecular tomography (FMT) assumes homogeneous distributions of the optical properties and normally results in reconstructions of low sensitivity. A natural enhancement is to incorporate diffuse optical tomography (DOT) to FMT. However, the traditional voxel-based DOT has been a severely ill-posed inverse problem and cannot retrieve the optical property distributions accurately. We present a structural-prior-based DOT method to effectively acquire the heterogeneous optical background with the aid of some imperfect structural priors from x-ray computed tomography and/or magnetic resonance imaging anatomical imaging modalities, and quantitatively compare its hard- and soft-prior schemes for achieving an improved recovery of the fluorescence distribution. Numerical simulations are conducted on a region-labeled three-dimensional (3D) digital mouse model to investigate the performance of this method. Physical experiments on a cylindrical phantom are also conducted to assess this methodology. Our simulated and experimental reconstruction results indicate that the structural-prior-based DOT guided FMT approach can significantly improve the sensitivity of FMT reconstruction, as well as its imaging resolution and quantitative accuracy. PMID:25402783

  9. Multiple reference optical coherence tomography (MR-OCT) system

    Science.gov (United States)

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

    2013-02-01

    We describe a multiple reference OCT (MR-OCT) system which is radically different from existing optical coherence tomography (OCT) systems. Complete scans of a target from surface to depth are accomplished by simultaneously acquiring the scan in multiple segments using a virtually solid state design that is inherently miniature, robust and low cost; in short, ideal for use in applications characterized by high volumes, difficult operating environments and constrained acquisition and operating budgets.

  10. Optical Coherence Tomography Imaging in Acute Coronary Syndromes

    OpenAIRE

    Atsushi Tanaka; Takashi Akasaka; Hironori Kitabata; Takashi Tanimoto; Yasushi Ino; Takashi Kubo

    2011-01-01

    Optical coherence tomography (OCT) is a high-resolution imaging technique that offers microscopic visualization of coronary plaques. The clear and detailed images of OCT generate an intense interest in adopting this technique for both clinical and research purposes. Recent studies have shown that OCT is useful for the assessment of coronary atherosclerotic plaques, in particular the assessment of plaque rupture, erosion, and intracoronary thrombus in patients with acute coronary syndrome. In ...

  11. Speckle attenuation in optical coherence tomography by curvelet shrinkage

    OpenAIRE

    Jian, Zhongping; Yu, Zhaoxia; Yu, Lingfeng; Rao, Bin; Chen, Zhongping; Tromberg, Bruce J.

    2009-01-01

    We describe an algorithm based on shrinkage in the curvelet domain to attenuate speckles in optical coherence tomography (OCT) images. The algorithm exploits the curvelet transform’s sparse representation of edge discontinuities that are common in OCT images and its ability to map signals and noise into different areas in the curvelet domain. The speckle attenuation is controlled by a single parameter that determines the threshold in the curvelet domain. Applying the algorithm to OCT images...

  12. Modified compressive sensing optical coherence tomography with noise reduction.

    Science.gov (United States)

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

    2012-10-15

    We study noise reduction using modified compressive sensing optical coherence tomography. We show that averaged modified compressed sensing (CS) reconstruction achieves better image quality in terms of signal-to-noise ratio, local contrast, and contrast-to-noise ratio, compared to the classical averaging method while reducing the total amount of data required to reconstruct the images. The same is also true when compared with standard CS-based averaging method with the same amount of undersampled data. PMID:23073413

  13. Methods for Monitoring Erosion Using Optical Coherence Tomography

    OpenAIRE

    Chan, Kenneth H.; Chan, Andrew C; Darling, Cynthia L.; Fried, Daniel

    2013-01-01

    Since optical coherence tomography is well suited for measuring small dimensional changes on tooth surfaces it has great potential for monitoring tooth erosion. The purpose of this study was to explore different approaches for monitoring the erosion of enamel. Application of an acid resistant varnish to protect the tooth surface from erosion has proven effective for providing a reference surface for in vitro studies but has limited potential for in vivo studies. Two approaches which can poten...

  14. Capturing the vital vascular fingerprint with optical coherence tomography

    OpenAIRE

    Liu, Gangjun; Chen, Zhongping

    2013-01-01

    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 p...

  15. Backscattering spectroscopic contrast with angle-resolved optical coherence tomography

    OpenAIRE

    Desjardins, Adrien E.; Vakoc, Benjamin J.; Tearney, Guillermo J.; Bouma, Brett E.

    2007-01-01

    Backscattering spectroscopic contrast using angle-resolved optical coherence tomography is demonstrated as a powerful method for determining scatterer diameter with subwavelength resolution. By applying spectroscopic digital processing algorithms to interferograms acquired in the frequency domain with a wavelength-swept laser centered at 1295 nm, it was shown that differences in wavelength-dependent backscattering from 0.3 and 1 ?m diameter microspheres can be clearly resolved. The observed ...

  16. 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.

  17. 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.

  18. Local inversions in ultrasound-modulated optical tomography

    International Nuclear Information System (INIS)

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

  19. Passive endoscopic polarization sensitive optical coherence tomography with completely fiber based optical components

    Science.gov (United States)

    Cahill, Lucas; Lee, Anthony M. D.; Pahlevaninezhad, Hamid; Ng, Samson; MacAulay, Calum E.; Poh, Catherine; Lane, Pierre

    2015-03-01

    Polarization Sensitive Optical Coherence Tomography (PSOCT) is a functional extension of Optical Coherence Tomography (OCT) that is sensitive to well-structured, birefringent tissue such as scars, smooth muscle and cartilage. In this work, we present a novel completely fiber based swept source PSOCT system using a fiber-optic rotary pullback catheter. This PSOCT implementation uses only passive optical components and requires no calibration while adding minimal additional cost to a standard structural OCT imaging system. Due to its complete fiber construction, the system can be made compact and robust, while the fiber-optic catheter allows access to most endoscopic imaging sites. The 1.5mm diameter endoscopic probe can capture 100 frames per second at pullback speeds up to 15 mm/s allowing rapid traversal of large imaging fields. We validate the PSOCT system with known birefringent tissues and demonstrate in vivo PSOCT imaging of human oral scar tissue.

  20. Optical Coherence Tomography: Modeling and Applications

    DEFF Research Database (Denmark)

    Thrane, Lars

    2001-01-01

    An analytical model is presented that is able to describe the performance of OCT systems in both the single and multiple scattering regimes simultaneously. This model inherently includes the shower curtain effect, well-known for light propagation through the atmosphere. This effect has been omitted in previous theoretical models of OCT systems. It is demonstrated that the shower curtain effect is of utmost importance in the theoretical description of an OCT system. The analytical model, together with proper noise analysis of the OCT system, enables calculation of the SNR, where the optical properties of the tissue are taken into account. Furthermore, by using the model, it is possible to determine the lateral resolution of OCT systems at arbitrary depths in the scattering tissue. During the Ph.D. thesis project, an OCT system has been constructed, and the theoretical model is verified experimentally using this system. A demonstration of the imaging capabilities of the OCT system is given. Moreover, a novel truereflection OCT imaging algorithm, based on the new OCT model presented in this thesis, is demonstrated. Finally, a theoretical analysis of the Wigner phase-space distribution function for the OCT geometry, i.e., reflection geometry, is developed. As in the new OCT model, multiple scattered photons has been taken into account together with multiple scattering effects. As an important result, a novel method of creating images based on measurements of the momentum width of the Wigner phase-space distribution is presented, and compared with conventional OCT.

  1. Low-cost diffuse optical tomography for the classroom

    Science.gov (United States)

    Minagawa, Taisuke; Zirak, Peyman; Weigel, Udo M.; Kristoffersen, Anna K.; Mateos, Nicolas; Valencia, Alejandra; Durduran, Turgut

    2012-10-01

    Diffuse optical tomography (DOT) is an emerging imaging modality with potential applications in oncology, neurology, and other clinical areas. It allows the non-invasive probing of the tissue function using relatively inexpensive and safe instrumentation. An educational laboratory setup of a DOT system could be used to demonstrate how photons propagate through tissues, basics of medical tomography, and the concepts of multiple scattering and absorption. Here, we report a DOT setup that could be introduced to the advanced undergraduate or early graduate curriculum using inexpensive and readily available tools. The basis of the system is the LEGO Mindstorms NXT platform which controls the light sources, the detectors (photo-diodes), a mechanical 2D scanning platform, and the data acquisition. A basic tomographic reconstruction is implemented in standard numerical software, and 3D images are reconstructed. The concept was tested and developed in an educational environment that involved a high-school student and a group of post-doctoral fellows.

  2. Design of a multimodality breast-like phantom for combined diffuse optical tomography and ultrasound tomography (DOT-UST)

    Science.gov (United States)

    Ghijsen, Michael; Unlu, Burcin; Nalcioglu, Orhan; Gulsen, Gultekin

    2010-02-01

    The initial steps in fabricating a multimodality imaging phantom for combined diffuse optical tomography and ultrasound tomography (DOT-UST) are completed. Phantoms are intended to mimic the optical and acoustic properties of breast tissue for near infrared light and ultrasound in the vicinity of 2 MHz. So far, a prototype ultrasound tomography system has been designed and the acoustic attenuation coefficient of glass beads has been characterized. Furthermore, 8 cm diameter homogeneous cylindrical phantoms have been successfully constructed and it has been shown that an inclusion with object to background contrast of three can be comfortably detected with the prototype system.

  3. Diffuse optical tomography using wavelength-swept laser

    Science.gov (United States)

    Cho, Jaedu; Lim, Gukbin; Jeong, Myung Yung; Nalcioglu, Orhan; Kim, Chang-Seok; Gulsen, Gultekin

    2013-03-01

    The design and implementation of a diffuse optical tomography system using wavelength-swept laser is described. Rapid and continuous wavelength change is utilized for high speed spectral scanning from 775 nm to 875 nm optical wavelength. Maximum speed of wavelength repetition is 1 kHz and averaged output power of the wavelength-swept laser is 20 mW. A fiber-optic Sagnac interferometer is incorporated to conduct passive amplitude modulation of the wavelength-swept laser. It is shown that the wavelength-swept laser can be successfully incorporated to the DOT system, and then reduces wavelength-shifting time and hardware complexity in multi-wavelength DOT implementation.

  4. A Low-Cost Method for Optical Tomography

    Directory of Open Access Journals (Sweden)

    Mohammad Ali Ansari

    2012-07-01

    Full Text Available INTRODUCTION: In this study, arrangement of a low-cost optical tomography device compared to other methods such as frequency domain diffuse tomography or time domain diffuse tomography is reported. This low-cost diffuse optical imaging technique is based on the detection of light after propagation in tissue. These detected signals are applied to predict the location of in-homogeneities inside phantoms. The device is assessed for phantoms representing homogenous healthy breast tissues as well as those representing healthy breast tissues with a lesion inside.METHODS: A diode laser at 780nm and 50 mW is used as the light source. The scattered light is then collected from the outer surface of the phantom by a detector. Both laser and detector are fiber coupled. The detector fiber may turn around the phantom to collect light scattered at different angles. Phantoms made of intralipid as the scattering medium and ink as the absorbing medium are used as samples. Light is collected after propagation in the phantoms and the capability of the device in collecting data and detecting lesions inside the phantoms is assessed. The fact that the detection fiber orbits around the sample and detects light from various angles has eliminated the need to use several detectors and optical fibers. The results obtained from experiments are compared with the results obtained from a finite element method (FEM solution of diffusion equation in cylindrical geometry written in FORTRAN.RESULTS: The graphs obtained experimentally and numerically are in good accordance with each other. The device has been able to detect lesions up to 13 mm inside the biological phantom.CONCLUSION: The data achieved by the optical tomography device is compared with the data achieved via a FEM code written in FORTRAN. The results indicate that the presented device is capable of providing the correct pattern of diffusely backscattered and transmitted light. The data achieved from the device is in excellent correlation with the numerical solution of the diffusion equation. Therefore, results indicate the applicability of the reported device. This device may be used as a base for an optical imaging. It is also capable of detecting lesions inside the phantoms

  5. Observation of the pulp horn by swept source optical coherence tomography and cone beam computed tomography

    Science.gov (United States)

    Iino, Yoshiko; Yoshioka, Toshihiko; Hanada, Takahiro; Ebihara, Arata; Sunakawa, Mitsuhiro; Sumi, Yasunori; Suda, Hideaki

    2015-02-01

    Cone-beam computed tomography (CBCT) is one of the most useful diagnostic techniques in dentistry but it involves ionizing radiation, while swept source optical coherence tomography (SS-OCT) has been introduced recently as a nondestructive, real-time, high resolution imaging technique using low-coherence interferometry, which involves no ionizing radiation. The purpose of this study was to evaluate the ability of SS-OCT to detect the pulp horn (PH) in comparison with that of CBCT. Ten extracted human mandibular molars were used. After horizontally removing a half of the tooth crown, the distance from the cut dentin surface to PH was measured using microfocus computed tomography (Micro CT) (SL) as the gold standard, by CBCT (CL) and by SS-OCT (OL). In the SS-OCT images, only when PH was observed beneath the overlying dentin, the distance from the cut dentin surface to PH was recorded. If the pulp was exposed, it was defined as pulp exposure (PE). The results obtained by the above three methods were statistically analyzed by Spearman's rank correlation coefficient at a significance level of p CBCT images, suggesting that SS-OCT can be a useful tool for the detection of PH.

  6. Enhanced optical clearing of skin in vivo and optical coherence tomography in-depth imaging

    Science.gov (United States)

    Wen, Xiang; Jacques, Steven L.; Tuchin, Valery V.; Zhu, Dan

    2012-06-01

    The strong optical scattering of skin tissue makes it very difficult for optical coherence tomography (OCT) to achieve deep imaging in skin. Significant optical clearing of in vivo rat skin sites was achieved within 15 min by topical application of an optical clearing agent PEG-400, a chemical enhancer (thiazone or propanediol), and physical massage. Only when all three components were applied together could a 15 min treatment achieve a three fold increase in the OCT reflectance from a 300 ?m depth and 31% enhancement in image depth Zthreshold.

  7. 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...

  8. Optical coherence tomography guided peeling of macular epiretinal membrane

    Science.gov (United States)

    Hirano, Yoshio; Yasukawa, Tsutomu; Ogura, Yuichiro

    2011-01-01

    Optical coherence tomography (OCT) has emerged as a powerful diagnostic aid in disorders of the vitreoretinal juncture. The purpose of this study is to determine whether OCT can be used as an additional tool for evaluating an architecture including the thickened area, and the identifiable edge of a macular epiretinal membrane (ERM), and helping us to dissect the ERM from the retinal surface more easily and safely. In two cases with ERM, the edges of the membranes were detected by OCT, and the peeling of the membrane was started at the area easily. OCT guided ERM peeling might be useful for dissecting ERM membranes without any hesitation. PMID:21311654

  9. Volumetric (3D) compressive sensing spectral domain optical coherence tomography

    OpenAIRE

    Xu, Daguang; HUANG, Yong; KANG, JIN U.

    2014-01-01

    In this work, we proposed a novel three-dimensional compressive sensing (CS) approach for spectral domain optical coherence tomography (SD OCT) volumetric image acquisition and reconstruction. Instead of taking a spectral volume whose size is the same as that of the volumetric image, our method uses a sub set of the original spectral volume that is under-sampled in all three dimensions, which reduces the amount of spectral measurements to less than 20% of that required by the Shan-non/Nyquist...

  10. Optical coherence tomography scanning with a handheld vitreoretinal micromanipulator.

    Science.gov (United States)

    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 of B-mode and C-mode scans. PMID:23366050

  11. Handheld Optical Coherence Tomography Scanner for Primary Care Diagnostics

    OpenAIRE

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

    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...

  12. Extraction of tissue optical properties from optical coherence tomography images for diagnostic purposes

    OpenAIRE

    Thrane, L.; Frosz, Mh; Levitz, D.; Jorgensen, Tm; Andersen, Cb; Hansen, Pr; Valanciunaite, J.; Swartling, Johannes; Andersson-engels, Stefan; Tycho, A.; Yura, Ht; Andersen, Pe

    2005-01-01

    The concept of optical coherence tomography (OCT) for high-resolution imaging of tissues in vivo is introduced. Analytical and numerical models for describing and understanding the light propagation in samples imaged by OCT systems are presented. An analytical model for calculating the OCT signal based on the extended Huygens-Fresnel principle and valid both for single and multiple scattering regimes is outlined. From this model, an algorithm for extracting tissue optical properties for multi...

  13. 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

  14. Assessing carotid atherosclerosis by fiber-optic multispectral photoacoustic tomography

    Science.gov (United States)

    Hui, Jie; Li, Rui; Wang, Pu; Phillips, Evan; Bruning, Rebecca; Liao, Chien-Sheng; Sturek, Michael; Goergen, Craig J.; Cheng, Ji-Xin

    2015-03-01

    Atherosclerotic plaque at the carotid bifurcation is the underlying cause of the majority of ischemic strokes. Noninvasive imaging and quantification of the compositional changes preceding gross anatomic changes within the arterial wall is essential for diagnosis of disease. Current imaging modalities such as duplex ultrasound, computed tomography, positron emission tomography are limited by the lack of compositional contrast and the detection of flow-limiting lesions. Although high-resolution magnetic resonance imaging has been developed to characterize atherosclerotic plaque composition, its accessibility for wide clinical use is limited. Here, we demonstrate a fiber-based multispectral photoacoustic tomography system for excitation of lipids and external acoustic detection of the generated ultrasound. Using sequential ultrasound imaging of ex vivo preparations we achieved ~2 cm imaging depth and chemical selectivity for assessment of human arterial plaques. A multivariate curve resolution alternating least squares analysis method was applied to resolve the major chemical components, including intravascular lipid, intramuscular fat, and blood. These results show the promise of detecting carotid plaque in vivo through esophageal fiber-optic excitation of lipids and external acoustic detection of the generated ultrasound. This imaging system has great potential for serving as a point-ofcare device for early diagnosis of carotid artery disease in the clinic.

  15. 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.

  16. 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.

  17. Optical coherence tomography a clinical and technical update

    CERN Document Server

    Cunha-Vaz, José

    2012-01-01

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

  18. A new tool for painting diagnostics: Optical coherence tomography

    Science.gov (United States)

    Arecchi, T.; Bellini, M.; Corsi, C.; Fontana, R.; Materazzi, M.; Pezzati, L.; Tortora, A.

    2006-07-01

    Nondestructive techniques have seen successful growth in the last few years, and, among them, optical ones are widespread and extremely well received in the field of painting diagnostics because of their effectiveness and safety. At present, many techniques for nondestructive investigations of paintings are available; nevertheless, none of them is suitable for a quantitative characterization of varnish. However, varnish removal, either partial or complete, is a fundamental part of the cleaning process, which is an essential step in painting conservation. This critical process has been carried out, up to now, without the possibility of any non-destructive measurement for assessing the actual varnish thickness, but with microscopic observation of a detached microfragment. Optical coherence tomography (OCT) is a noninvasive technique that is well established for biomedical applications. In this work, we present a novel application of OCT to measure the varnish film thickness for painting diagnostics.

  19. Dynamic image reconstruction in time-resolved diffuse optical tomography

    Science.gov (United States)

    Powell, Samuel; Cooper, Robert J.; Hebden, Jeremy C.; Arridge, Simon R.

    2015-03-01

    Optical imaging techniques provide a means of monitoring haemodynamics and tissue oxygenation by virtue of the differing absorption spectra of relevant endogenous chromophores. Whilst time-domain diffuse optical tomography offers sufficient sensitivity to produce full three dimensional images of such properties through the entire infant brain, standard approaches to the imaging protocol and reconstruction methods limit the temporal resolution which can be achieved without an unacceptable degradation in the image quality. In this work we employ spatio-temporal regularisation by means of a variational form Kalman filter to achieve significantly improved temporal resolution whilst maintaining image quality. We demonstrate this approach in a dynamic phantom study where we successfully track moving absorbing and scattering targets using the MONSTIR II instrument developed at University College London.

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

    Science.gov (United States)

    Jordan, K.

    2013-06-01

    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.

  1. Optical Coherence Tomography for Examination of Parchment Degradation

    International Nuclear Information System (INIS)

    A novel application of Optical Coherence Tomography utilizing infrared light of 830 nm central wavelength for non invasive examination of the structure of parchment, some covered with iron gall ink, is presented. It is shown that both the parchment and the ink applied are sufficiently transparent to light of this wavelength. In the study, Spectral OCT (SOCT) as well as Polarisation Sensitive OCT (PS-OCT) techniques were used to obtain cross-sectional images of samples of parchment based on scattering properties. The second technique was additionally employed to recover the birefringence properties and the optical axis orientations of the sample. It was shown that freshly produced parchment exhibits a degree of birefringence. However, this property declines with ageing, and samples of old parchment completely depolarise the incident light.

  2. Weighted filtered backprojection for quantitative fluorescence optical projection tomography

    International Nuclear Information System (INIS)

    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

  3. 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

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

    Directory of Open Access Journals (Sweden)

    Gaurav Sanghi

    2014-01-01

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

  7. Optimisation of post mortem cardiac computed tomography compared to optical coherence tomography and histopathology - Technical note

    DEFF Research Database (Denmark)

    Precht, Helle; Leth, Peter Mygind

    2014-01-01

    Introduction: Coronary atherosclerosis is a leading cause of mortality. New technological developments in computed tomography (CT), including dual energy, iterative reconstructions and high definition scanning, could significantly improve the non-invasive identification of atherosclerosis plaques. Here, a new method for optimising cardiac coronary CT with optical coherence tomography (OCT) and histopathology is presented. Materials and methods: Twenty human hearts obtained from autopsies were used. A contrast agent that solidifies after cooling was injected into the coronary arteries. CT scanning was performed on the heart alone as well as with the heart in a chest phantom. We used eight different CT protocols and the newest CT technique to image every heart. The OCT and CT images were compared with their corresponding histological sections. A procedure for ensuring the correct alignment of the images was also developed. Results: We have succeeded in developing a new method for post-mortem coronary CT angiography in which an autopsy heart is placed in a chest phantom to simulate clinical CT. Conclusion: The new method permits comparison of CT with OCT and histopathology. This method can also be used for evaluating coronary artery disease, including characterising plaques, and will eventually allow for the detection of rupture-prone plaques, which we will assess in a future study. Clinical testing is our ultimate goal. © 2013 Elsevier Ltd.

  8. Histologic models for optical tomography and spectroscopy of tissues

    Science.gov (United States)

    Bhargava, Rohit; Davis, Brynmor J.

    2009-02-01

    Histologic information is often the ground truth against which imaging technology performance is measured. Typically, this information is limited, however, due to the need to excise tissue, stain it and have the tissue section manually reviewed. As a consequence, histologic models of actual tissues are difficult to acquire and are generally prohibitively expensive. Models and phantoms for imaging development, hence, have to be simple and reproducible for concordance between different groups developing the same imaging methods but may not reflect tissue structure. Here, we propose a route to histologic information that does not involve the use of human review nor does it require specialized dyes or stains. We combine mid-infrared Fourier transform infrared (FT-IR) spectroscopy with imaging to record data from tissue sections. Attendant numerical algorithms are used to convert the data to histologic information. Additionally, the biochemical nature of the recorded information can be used to generate contrast for other modalities. We propose that this histologic model and spectroscopic generation of contrast can serve as standard for testing and design aid for tomography and spectroscopy of tissues. We discuss here the biochemical and statistical issues involved in creating histologic models and demonstrate the use of the approach in generating optical coherence tomography (OCT) images of prostate tissue samples.

  9. Monitoring changes of optical attenuation coefficients of acupuncture points during laser acupuncture by optical coherence tomography

    Science.gov (United States)

    Huang, Yimei; Yang, Hongqin; Wang, Yuhua; Zheng, Liqin; Xie, Shusen

    2010-11-01

    The physical properties of acupuncture point were important to discover the mechanism of acupuncture meridian. In this paper, we used an optical coherence tomography to monitor in vivo the changes of optical attenuation coefficients of Hegu acupuncture point and non-acupuncture point during laser irradiation on Yangxi acupuncture point. The optical attenuation coefficients of Hegu acupuncture point and non-acupuncture point were obtained by fitting the raw data according to the Beer-Lambert's law. The experimental results showed that the optical attenuation coefficient of Hegu acupuncture point decreased during the laser acupuncture, in contrast to a barely changed result in that of non-acupuncture point. The significant change of optical attenuation coefficient of Hegu acupuncture point indicated that there was a correlation between Hegu and Yangxi acupuncture points to some extent.

  10. Metrological reliability of optical coherence tomography in biomedical applications

    International Nuclear Information System (INIS)

    Optical coherence tomography (OCT) has been proving to be an efficient diagnostics technique for imaging in vivo tissues, an optical biopsy with important perspectives as a diagnostic tool for quantitative characterization of tissue structures. Despite its established clinical use, there is no international standard to address the specific requirements for basic safety and essential performance of OCT devices for biomedical imaging. The present work studies the parameters necessary for conformity assessment of optoelectronics equipment used in biomedical applications like Laser, Intense Pulsed Light (IPL), and OCT, targeting to identify the potential requirements to be considered in the case of a future development of a particular standard for OCT equipment. In addition to some of the particular requirements standards for laser and IPL, also applicable for metrological reliability analysis of OCT equipment, specific parameters for OCT's evaluation have been identified, considering its biomedical application. For each parameter identified, its information on the accompanying documents and/or its measurement has been recommended. Among the parameters for which the measurement requirement was recommended, including the uncertainty evaluation, the following are highlighted: optical radiation output, axial and transverse resolution, pulse duration and interval, and beam divergence

  11. 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.

  12. Optical Coherence Tomography Imaging in Acute Coronary Syndromes

    Science.gov (United States)

    Kubo, Takashi; Ino, Yasushi; Tanimoto, Takashi; Kitabata, Hironori; Tanaka, Atsushi; Akasaka, Takashi

    2011-01-01

    Optical coherence tomography (OCT) is a high-resolution imaging technique that offers microscopic visualization of coronary plaques. The clear and detailed images of OCT generate an intense interest in adopting this technique for both clinical and research purposes. Recent studies have shown that OCT is useful for the assessment of coronary atherosclerotic plaques, in particular the assessment of plaque rupture, erosion, and intracoronary thrombus in patients with acute coronary syndrome. In addition, OCT may enable identifying thin-cap fibroatheroma, the proliferation of vasa vasorum, and the distribution of macrophages surrounding vulnerable plaques. With its ability to view atherosclerotic lesions in vivo with such high resolution, OCT provides cardiologists with the tool they need to better understand the thrombosis-prone vulnerable plaques and acute coronary syndromes. This paper reviews the possibility of OCT for identification of vulnerable plaques in vivo. PMID:21941666

  13. Spectralis optical coherence tomography findings in Welder?s maculopathy

    Directory of Open Access Journals (Sweden)

    Aniruddha Mahindrakar

    2013-01-01

    Full Text Available Welder?s maculopathy is a form of photochemical damage to the retina and is typically characterized by involvement of the outer retinal layers. Spectral domain optical coherence tomography (SD-OCT imaging was performed in three eyes of two patients with clinical findings suggestive of Welder?s maculopathy in occupational welders. A faceted foveal lesion characterized clinical examination and the SD-OCT line scans images showed a distinct discontinuity of the photoreceptor inner and outer segment (IS/OS junction. The external limiting membrane (ELM and the retinal pigment epithelial (RPE layer remained intact at the site of IS/OS defect. SD-OCT imaging offers a noninvasive way of evaluating the microstructural changes at the fovea in Welder?s maculopathy.

  14. 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.

  15. Optical coherence tomography of the epidermal sulfakrilate surface strippings

    Directory of Open Access Journals (Sweden)

    Utz S.R.

    2013-09-01

    Full Text Available Method of the epidermal surface biopsy (ESB with the adhesive compositions is the alter-native to the classic his-tological examination. Materials and Methods. In this study medical adhesive "Sulfacrylate" was used, small portions of which had been spread on an object glass, and then on different skin areas. To study the structural organization of the samples ESB the technique of optical coherence tomography (??? was used. Results. We obtained the pictures that visualize the structural organization of the different layers of the epidermis in lichen planus, hyperkeratosis, scabies and other skin diseases. Conclusion. This technique allows non-invasive measurement of high-precision structure of different layers of the epidermis, which can be useful both for research and for the practical dermatology.

  16. Specificity of noninvasive blood glucose monitoring with optical coherence tomography

    Science.gov (United States)

    Larin, Kirill V.; Ashitkov, Taras V.; Motamedi, Massoud; Esenaliev, Rinat O.

    2003-07-01

    Management of diabetic disease requires frequent monitoring of blood glucose concentration. Development of a noninvasive technique capable of reliable and sensitive monitoring of blood glucose concentration would considerably improve quality of life of diabetic patients and reduce mortality associated with this disease. Recently, we proposed to use Optical Coherence Tomography (OCT) technique for noninvasive glucose monitoring. In this paper, we tested in animals several aspects of specificity of noninvasive blood glucose monitoring with the OCT technique. Influence of temperature and tissue heterogeneity on the OCT signal profile is experimentally studied in this paper. We also theoretically investigated the changes in tissue scattering induced by variation of concentration of glucose and other osmolytes. Obtained results suggest that although several physical and chemical agents could potentially interfere with blood glucose concentration measurements using the OCT technique, their effect is smaller compared to that of glucose under normal physiological conditions.

  17. Dark-field full-field optical coherence tomography.

    Science.gov (United States)

    Auksorius, Egidijus; Claude Boccara, A

    2015-07-15

    Full-field optical coherence tomography (FF-OCT) provides en face images from deep in the tissue with high spatial resolution. Specular reflections, however, may reduce image contrast as it can be much stronger than the backscattered signal from a specimen. To this end, we demonstrate dark-field FF-OCT (d-FF-OCT) that can block specular reflections by the help of an opaque disk in the pupil-conjugated plane. The reference mirror is replaced by a blazed grating, which eliminates a walk-off between the sample and the reference beams on a camera that otherwise limits the imaging field-of-view (FOV). We show that d-FF-OCT can suppress specular reflections efficiently from the glass-specimen interface by at least two orders of magnitude and yield higher contrast images compared to the conventional FF-OCT. PMID:26176447

  18. 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.

  19. Evaluation of microfluidic channels with optical coherence tomography

    KAUST Repository

    Czajkowski, J.

    2010-06-25

    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.

  20. Variational Inference With ARD Prior for NIRS Diffuse Optical Tomography.

    Science.gov (United States)

    Miyamoto, Atsushi; Watanabe, Kazuho; Ikeda, Kazushi; Sato, Masa-Aki

    2015-05-01

    Diffuse optical tomography (DOT) reconstructs 3-D tomographic images of brain activities from observations by near-infrared spectroscopy (NIRS) that is formulated as an ill-posed inverse problem. This brief presents a method for NIRS DOT based on a hierarchical Bayesian approach introducing the automatic relevance determination prior and the variational Bayes technique. Although the sparseness of the estimation strongly depends on the hyperparameters, in general, our method has less dependency on the hyperparameters. We confirm through numerical experiments that a schematic phase diagram of sparseness with respect to the hyperparameters has two regions: in one region hyperparameters give sparse solutions and in the other they give dense ones. The experimental results are supported by our theoretical analyses in simple cases. PMID:25881370

  1. 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.

  2. 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.

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

    OpenAIRE

    Tycho, Andreas; Bjarklev, Anders Overgaard; Andersen, Peter E.

    2006-01-01

    An advanced novel Monte Carlo simulation model of the detection process of an optical coherence tomography (OCT) system is presented. For the first time it is shown analytically that the applicability of the incoherent Monte Carlo approach to model the heterodyne detection process of an OCT system is firmly justified. This is obtained by calculating the heterodyne mixing of the reference and sample beams in a plane conjugate to the discontinuity in the sample probed by the system. Using this ...

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

    International Nuclear Information System (INIS)

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

  5. 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°

  6. 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.

  7. Sound field reconstruction using acousto-optic tomography.

    Science.gov (United States)

    Torras-Rosell, Antoni; Barrera-Figueroa, Salvador; Jacobsen, Finn

    2012-05-01

    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 of the very same sound field measured with a traditional microphone array. PMID:22559354

  8. Optical coherence tomography visualizes neurons in human entorhinal cortex

    Science.gov (United States)

    Magnain, Caroline; Augustinack, Jean C.; Konukoglu, Ender; Frosch, Matthew P.; Sakadži?, Sava; Varjabedian, Ani; Garcia, Nathalie; Wedeen, Van J.; Boas, David A.; Fischl, Bruce

    2015-01-01

    The cytoarchitecture of the human brain is of great interest in diverse fields: neuroanatomy, neurology, neuroscience, and neuropathology. Traditional histology is a method that has been historically used to assess cell and fiber content in the ex vivo human brain. However, this technique suffers from significant distortions. We used a previously demonstrated optical coherence microscopy technique to image individual neurons in several square millimeters of en-face tissue blocks from layer II of the human entorhinal cortex, over 50 µm in depth. The same slices were then sectioned and stained for Nissl substance. We registered the optical coherence tomography (OCT) images with the corresponding Nissl stained slices using a nonlinear transformation. The neurons were then segmented in both images and we quantified the overlap. We show that OCT images contain information about neurons that is comparable to what can be obtained from Nissl staining, and thus can be used to assess the cytoarchitecture of the ex vivo human brain with minimal distortion. With the future integration of a vibratome into the OCT imaging rig, this technique can be scaled up to obtain undistorted volumetric data of centimeter cube tissue blocks in the near term, and entire human hemispheres in the future. PMID:25741528

  9. Morphological phenotyping of mouse hearts using optical coherence tomography

    Science.gov (United States)

    Cua, Michelle; Lin, Eric; Lee, Ling; Sheng, Xiaoye; Wong, Kevin S. K.; Tibbits, Glen F.; Beg, Mirza Faisal; Sarunic, Marinko V.

    2014-11-01

    Transgenic mouse models have been instrumental in the elucidation of the molecular mechanisms behind many genetically based cardiovascular diseases such as Marfan syndrome (MFS). However, the characterization of their cardiac morphology has been hampered by the small size of the mouse heart. In this report, we adapted optical coherence tomography (OCT) for imaging fixed adult mouse hearts, and applied tools from computational anatomy to perform morphometric analyses. The hearts were first optically cleared and imaged from multiple perspectives. The acquired volumes were then corrected for refractive distortions, and registered and stitched together to form a single, high-resolution OCT volume of the whole heart. From this volume, various structures such as the valves and myofibril bundles were visualized. The volumetric nature of our dataset also allowed parameters such as wall thickness, ventricular wall masses, and luminal volumes to be extracted. Finally, we applied the entire acquisition and processing pipeline in a preliminary study comparing the cardiac morphology of wild-type mice and a transgenic mouse model of MFS.

  10. Vascular wall stress during intravascular optical coherence tomography imaging

    Science.gov (United States)

    Sun, Cuiru; Yang, Victor

    2015-03-01

    Biomechanical properties of arterial wall is crucial for understanding the changes in the cardiovascular system. Catheters are used during intravascular optical coherence tomography (IVOCT) imaging. The presence of a catheter alters the flow field, pressure distribution and frictional resistance to flow in an artery. In this paper, we first study the transmural stress distribution of the catheterized vessel. COMSOL (COMSOL 4.4) was used to simulate the blood flow induced deformation in a catheterized vessel. Blood is modeled as an incompressible Newtonian fluid. Stress distribution from an three-layer vascular model with an eccentric catheter are simulated, which provides a general idea about the distribution of the displacement and the stress. Optical coherence elastography techniques were then applied to porcine carotid artery samples to look at the deformation status of the vascular wall during saline or water injection. Preliminary simulation results show nonuniform stress distribution in the circumferential direction of the eccentrically catheterized vascular model. Three strain rate methods were tested for intravascular OCE application. The tissue Doppler method has the potential to be further developed to image the vascular wall biomechnical properties in vivo. Although results in this study are not validated quantitatively, the experiments and methods may be valuable for intravascular OCE studies, which may provide important information for cardiovascular disease prevention, diagnosis and treatment.

  11. Depth Compensated Spectral Domain Optical Coherence Tomography via Digital Compensation

    CERN Document Server

    Boroomand, Ameneh; Shafiee, Mohammad Javad; Bizheva, Kostadinka; Wong, Alexander

    2015-01-01

    Spectral Domain Optical Coherence Tomography (SD-OCT) is a well-known imaging modality which allows for \\textit{in-vivo} visualization of the morphology of different biological tissues at cellular level resolutions. The overall SD-OCT imaging quality in terms of axial resolution and Signal-to-Noise Ratio (SNR) degrades with imaging depth, while the lateral resolution degrades with distance from the focal plane. This image quality degradation is due both to the design of the SD-OCT imaging system and the optical properties of the imaged object. Here, we present a novel Depth Compensated SD-OCT (DC-OCT) system that integrates a Depth Compensating Digital Signal Processing (DC-DSP) module to improve the overall imaging quality via digital compensation. The designed DC-DSP module can be integrated to any SD-OCT system and is able to simultaneously compensate for the depth-dependent loss of axial and lateral resolutions, depth-varying SNR, as well as sidelobe artifact for improved imaging quality. The integrated D...

  12. 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.

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

    Directory of Open Access Journals (Sweden)

    Janusz Michalewski

    2014-01-01

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

  14. Root canal filling evaluation using optical coherence tomography

    Science.gov (United States)

    Negrutiu, Meda L.; Sinescu, Cosmin; Topala, Florin; Nica, Luminita; Ionita, Ciprian; Marcauteanu, Corina; Goguta, Luciana; Bradu, Adrian; Dobre, George; Rominu, Mihai; Podoleanu, Adrian Gh.

    2010-04-01

    Endodontic therapy consists in cleaning and shaping the root canal system, removing organic debris and sealing the intra-canal space with permanent filling materials. The purpose of this study was to evaluate various root canal fillings in order to detect material defects, the marginal adaptation at the root canal walls and to assess the quality of the apical sealing. 21 extracted single-root canal human teeth were selected for this study. We instrumented all roots using NiTi rotary instruments. All canals were enlarged with a 6% taper size 30 GT instrument, 0,5 mm from the anatomical apex. The root canals were irrigated with 5% sodium hypochlorite, followed by 17% ethylenediaminetetraacetic acid (EDTA). After the instrumentation was completed, the root canals were obturated using a thermoplasticizable polymer of polyesters. In order to assess the defects inside the filling material and the marginal fit to the root canal walls, the conebeam micro-computed tomography (CB?CT) was used first. After the CB?CT investigation, time domain optical coherence tomography working in en face mode (TDefOCT) was employed to evaluate the previous samples. The TDefOCT system was working at 1300 nm and was doubled by a confocal channel at 970 nm. The results obtained by CB?CT revealed no visible defects inside the root-canal fillings and at the interfaces with the root-canal walls. TDefOCT investigations permit to visualize a more complex stratificated structure at the interface filling material/dental hard tissue and in the apical region.

  15. Differentiating Glaucomatous from Non-Glaucomatous Optic Nerve Cupping by Optical Coherence Tomography

    Science.gov (United States)

    Gupta, Preeya K; Asrani, Sanjay; Freedman, Sharon F; El-Dairi, Mays; Bhatti, M Tariq

    2011-01-01

    Background: In clinical practice, the differentiation of glaucomatous from non-glaucomatous cupping can be difficult, even for experienced observers. The purpose of this study was to evaluate the role of optical coherence tomography (OCT) in differentiating glaucomatous from non-glaucomatous optic nerve cupping in a cross-sectional pilot study. Methods: Eleven consecutive patients presenting to the Duke Eye Center from September 2007 to July 2008 with non-glaucomatous optic nerve cupping and 12 patients with glaucomatous optic nerve cupping were identified. All patients underwent Stratus® OCT imaging: fast macular map, fast retinal nerve fiber layer (RNFL) 3.4 thickness, and fast optic disc protocols. Automated visual field perimetry was performed on the date of OCT scan in non-glaucomatous cupping patients, and from 0-9 months of scan date in glaucoma patients. Eyes were matched by optic nerve cup-to-disc area ratio; average and mean deviation were calculated for each variable. Results: For a similar average RNFL, patients with non-glaucomatous optic nerve cupping had lower nasal and temporal RNFL thickness, as well as lower macular thickness and volume compared to patients with glaucomatous optic nerve cupping. Conclusion: OCT appears to be a useful technology in differentiating glaucomatous from non-glaucomatous optic nerve cupping. The pattern of RNFL loss appears more diffuse in non-glaucomatous optic nerve cupping compared to glaucomatous optic nerve cupping. Future studies with larger sample size and specific neuro-ophthalmic causes of optic nerve cupping may further elucidate the role of OCT in this clinical setting. PMID:21532867

  16. Correlation of endoscopic optical coherence tomography with histology

    Science.gov (United States)

    Westphal, Volker; Rollins, Andrew M.; Willis, Joseph; Sivak, Michael J., Jr.; Izatt, Joseph A.

    2000-04-01

    Optical Coherence Tomography (OCT) is a noninvasive optical imaging technique that allows high-resolution cross- sectional imaging of tissue microstructure. We have recently developed a system for endoscopic OCT (EOCT) to examine the gastrointestinal tract of humans in vivo. Compared to endoscopic ultrasonic devices it offers a higher resolution and does not require coupling gels or fluids. EOCT may lead to a versatile tool for biopsy site selection or optical biopsy itself. The EOCT unit is comprised of an interferometer unit with a high speed scanning reference arm and an endoscopically compatible radially scanning probe as the sample arm. Fast data acquisition allows real-time display. Temporal averaging for speckle reduction and a transformation to correct nonlinear scanning were included in the EOCT control software, both in real-time. During in vivo clinical trials, we have observe the structure of the mucosa and submucosa in several gastrointestinal organs as well as glands, blood vessels, pits, villi and crypts. The purpose of this study was to correlate images acquired in vitro with EOCT to corresponding histological sections. EOCT images were obtained on fresh specimens, which were then fixed in formalin and submitted for standard histology. Tissues examined were normal specimens, which were then fixed in formalin and submitted for standard histology. Tissues examined were normal specimens of stomach, ileum, colon and rectum. It was shown that he thickness of the mucosa correlates well with the first bright layer in EOCT. The R2-value was determined to be 0.69. The submucosa and the muscularis propria could be identified. Furthermore, we were able to show the effect of pressure on the tissue on the visible details in the EOCT images.

  17. Focusing optics of a parallel beam CCD optical tomography apparatus for 3D radiation gel dosimetry.

    Science.gov (United States)

    Krstaji?, Nikola; Doran, Simon J

    2006-04-21

    Optical tomography of gel dosimeters is a promising and cost-effective avenue for quality control of radiotherapy treatments such as intensity-modulated radiotherapy (IMRT). Systems based on a laser coupled to a photodiode have so far shown the best results within the context of optical scanning of radiosensitive gels, but are very slow ( approximately 9 min per slice) and poorly suited to measurements that require many slices. Here, we describe a fast, three-dimensional (3D) optical computed tomography (optical-CT) apparatus, based on a broad, collimated beam, obtained from a high power LED and detected by a charged coupled detector (CCD). The main advantages of such a system are (i) an acquisition speed approximately two orders of magnitude higher than a laser-based system when 3D data are required, and (ii) a greater simplicity of design. This paper advances our previous work by introducing a new design of focusing optics, which take information from a suitably positioned focal plane and project an image onto the CCD. An analysis of the ray optics is presented, which explains the roles of telecentricity, focusing, acceptance angle and depth-of-field (DOF) in the formation of projections. A discussion of the approximation involved in measuring the line integrals required for filtered backprojection reconstruction is given. Experimental results demonstrate (i) the effect on projections of changing the position of the focal plane of the apparatus, (ii) how to measure the acceptance angle of the optics, and (iii) the ability of the new scanner to image both absorbing and scattering gel phantoms. The quality of reconstructed images is very promising and suggests that the new apparatus may be useful in a clinical setting for fast and accurate 3D dosimetry. PMID:16585845

  18. 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.

  19. 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

  20. 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...

  1. Ex vivo imaging of human thyroid pathology using integrated optical coherence tomography and optical coherence microscopy

    Science.gov (United States)

    Zhou, Chao; Wang, Yihong; Aguirre, Aaron D.; Tsai, Tsung-Han; Cohen, David W.; Connolly, James L.; Fujimoto, James G.

    2010-01-01

    We evaluate the feasibility of optical coherence tomography (OCT) and optical coherence microscopy (OCM) for imaging of benign and malignant thyroid lesions ex vivo using intrinsic optical contrast. 34 thyroid gland specimens are imaged from 17 patients, covering a spectrum of pathology ranging from normal thyroid to benign disease/neoplasms (multinodular colloid goiter, Hashimoto's thyroiditis, and follicular adenoma) and malignant thyroid tumors (papillary carcinoma and medullary carcinoma). Imaging is performed using an integrated OCT and OCM system, with thyroid tissues. With further development of needle-based imaging probes, OCT and OCM could be promising techniques to use for the screening of thyroid nodules and to improve the diagnostic specificity of fine needle aspiration evaluation.

  2. 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.

  3. 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

  4. 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

  5. The use of optical coherence tomography in maxillofacial surgery

    Science.gov (United States)

    Al-Obaidi, Mohammed; Tandon, Rahul; Tiwana, Paul

    2015-02-01

    The ever-evolving medical field continues to trend toward less invasive approaches to the diagnosis and treatment of pathological conditions. Basic sciences research has allowed for improved technologies that are translated to the clinical sciences. Similarly, advancements in imaging modalities continue to improve and their applications become more varied. As such, surgeons and pathologists are able to depend on smaller samples for tissue diagnosis of pathological disease, where once large sections of tissue were needed. Optical coherence tomography (OCT), a high-resolution imaging technique, has been used extensively in different medical fields to improve diagnostic yield. Its use in dental fields, particularly in oral and maxillofacial surgery, remains limited. Our goal is to assess the use of OCT for improving soft tissue analysis and diagnosis, particularly for its applications in the field of oral and maxillofacial surgery. Optical coherence tomography is a modality that uses an optical signal using safe near-infrared light which is reflected off the sub-surface structures. This allows for high-resolution cross-sectional images of the tissue morphology to be obtained. Ophthalmologists have been using OCT to obtain images of the retina to assess for age-related macular degeneration. More recently, OCT has been used by Interventional Cardiology to image coronary arteries, and assess plaque thickness and morphology. This technology is now being investigated in several medical fields as a form of optical biopsy, providing in situ images with high-resolution morphology of tissues. We are particularly interested in its use on epithelial tissues, and therefore performed a literature review on the use of OCT for assessing epithelium. Evaluation of histologically-diagnosed actinic keratosis, for example, was found to correlate well with the imaging discrepancies found on OCT; and the in vivo assessment of atypical keratinocytes was firmly established. Additionally, studies have shown a potential application in that OCT may provide a method for studying the evolution of epithelial lesions OCT's potential in producing high-resolution images of tissue morphology can prove to be a valuable tool for characterizing different soft tissue pathological disorders. Furthermore, it has been shown to measure changes in light intensity at tissue-fluid interfaces, which can provide surgeons the ability to characterize oral mucosal surfaces noninvasively. OCT can also prove to be valuable in detecting oral cancerous and pre-cancerous lesions, as altered epithelium containing increased dysplasia shows differences in light scattering than normal epithelium. Additionally, OCT has been shown to analyze deeper collagen tissues of the oral mucosa and is not limited to the surface epithelium. This can aid in characterizing such inflammatory conditions that alter these tissues. Several tissue samples from the maxillofacial region were obtained and assessed using an OCT device at our institution. The analysis has shown high-resolution images of soft tissue-bone interface, titanium implant-bone interface, and other anatomical sites within the oral cavity. OCT has been shown to be a valuable modality in different medical fields. Its use in oral and maxillofacial surgery can potentially aid in diagnostic techniques. Alongside traditional histological technique, it can be help characterize tissues at the cellular level, which would improve costs, time, and most importantly, patient care. We aim to introduce OCT and its diagnostic abilities to the field of oral and maxillofacial surgery to help aid clinicians and provide improved care for patients.

  6. Imaging of collagen deposition disorders using optical coherence tomography

    DEFF Research Database (Denmark)

    Ring, H C; Mogensen, M

    2015-01-01

    BACKGROUND: Collagen deposition disorders such as hypertrophic scars, keloids and scleroderma can be associated with significant stigma and embarrassment. These disorders often constitute considerable impairment to quality of life, with treatment posing to be a substantial challenge. Optical coherence tomography (OCT) provides a non-invasive, easily applicable bedside optical imaging method for assessment of the skin. It is hypothesized that OCT imaging may be useful in assessing fibrosis to avoid additional biopsies that could potentially worsen the scarring. METHOD: Thirty-three patients with ordinary scars, hypertrophic scars, keloid scarring, lichen sclerosus et atrophicus and localized or systemic scleroderma were recruited for this pilot study. Affected tissue and adjacent healthy skin were scanned using OCT and digitally photographed. Density measurements were performed in ImageJ on OCT images from scleroderma patients, both systemic and morphea (10 patients), keloid patients (10 patients) and healthyskin adjacent to keloids (10 patients). RESULTS: OCT images of scarring diseases showed varying degrees of disruption to the skin architecture. OCT characteristics were identified for each lesion type. Hypertrophic scars displayed an increased vascularity and signal-rich bands correlating to excessive collagen deposition. Keloids depicted a disarray of hyper-reflective areas primarily located in the upper dermis. Additionally, the dermis displayed a heterogeneous morphology without indications of any vascular supply or lymphatic network. In contrast to keloids, scleroderma displayed a more cohesive backscattering indicating a difference in density of collagen or other dermal structures. OCT images demonstrated no significant differences between mean density measurements in OCT images of scleroderma, keloid and healthy skin (P = 0.07). CONCLUSION: The OCT imaging appears to identify different scarring mechanisms, and therefore be of potential use in the assessment of outcomes following non-invasive therapy of e.g. early or progressive lesions.

  7. Optical diffraction tomography: accuracy of an off-axis reconstruction

    Science.gov (United States)

    Kostencka, Julianna; Kozacki, Tomasz

    2014-05-01

    Optical diffraction tomography is an increasingly popular method that allows for reconstruction of three-dimensional refractive index distribution of semi-transparent samples using multiple measurements of an optical field transmitted through the sample for various illumination directions. The process of assembly of the angular measurements is usually performed with one of two methods: filtered backprojection (FBPJ) or filtered backpropagation (FBPP) tomographic reconstruction algorithm. The former approach, although conceptually very simple, provides an accurate reconstruction for the object regions located close to the plane of focus. However, since FBPJ ignores diffraction, its use for spatially extended structures is arguable. According to the theory of scattering, more precise restoration of a 3D structure shall be achieved with the FBPP algorithm, which unlike the former approach incorporates diffraction. It is believed that with this method one is allowed to obtain a high accuracy reconstruction in a large measurement volume exceeding depth of focus of an imaging system. However, some studies have suggested that a considerable improvement of the FBPP results can be achieved with prior propagation of the transmitted fields back to the centre of the object. This, supposedly, enables reduction of errors due to approximated diffraction formulas used in FBPP. In our view this finding casts doubt on quality of the FBPP reconstruction in the regions far from the rotation axis. The objective of this paper is to investigate limitation of the FBPP algorithm in terms of an off-axis reconstruction and compare its performance with the FBPJ approach. Moreover, in this work we propose some modifications to the FBPP algorithm that allow for more precise restoration of a sample structure in off-axis locations. The research is based on extensive numerical simulations supported with wave-propagation method.

  8. 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

  9. 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.

  10. Fluorescence diffuse optical tomography with structural a priori information

    Science.gov (United States)

    Lin, Yuting; Nalcioglu, Orhan; Gulsen, Gultekin

    2008-02-01

    Fluorescence diffuse optical tomography (FT) is an emerging molecular imaging technique that can spatially resolve both fluorophore concentration and lifetime parameters. In this study, we investigated the performance of a frequency domain FT system for inclusions with various sizes and contrast levels. Due to the ill-posedness of the FT problem, the fluorescence parameters can not be recovered accurately. The reconstructed fluorescence parameters depend on the signal to background contrast and size of the compartments containing the fluorophores. Recently, imaging with multiple modalities has become a popular trend. Different modalities give different information on the subject under investigation. Here, we evaluated the improvement in FT reconstruction when structural a priori information from a second imaging modality was incorporated. The results demonstrated that the structural a priori information was crucial to be able to recover both parameters with high accuracy. Without such a priori information, the same fluorophore concentration for different object sizes could not be recovered to the same value. On the other hand, when the structural a priori information was available, both fluorescence parameters could be recovered within 15% error for all the cases.

  11. NIR time domain diffuse optical tomography experiments on human forearm

    Science.gov (United States)

    Zhao, Huijuan; Gao, Feng; Tanikawa, Yukari; Homma, Kazuhiro; Yamada, Yukio

    2003-07-01

    To date, the applications of near infrared (NIR) diffusion optical tomography (DOT) are mostly focused on the potential of imaging woman breast, human head hemodynamics and neonatal head. For the neonates, who are suffered from ischaemia or hemorrhages in brain, bedside monitoring of the cerebral perfusion situation, e.g., the blood oxygen saturation and blood volume, is necessary for avoiding permanent injure. NIR DOT is on the promising tools because it is noninvasive, smaller in size, and moveable. Prior to achieving the ultimate goal of imaging infant brain and woman breast using DOT, in this paper, the developed methodologies are justified by imaging in vivo human forearms. The absolute absorption- and scattering-coefficient images revealed the inner structure of the forearm and the bones were clearly distinguished from the muscle. The differential images showed the changes in oxy-hemoglobin, deoxy-hemoglobin and blood volume during the hand-gripping exercises, which are consistent with the physiological process reported on literatures.

  12. Optical coherence tomography surveillance following drug-eluting stent implantation.

    Science.gov (United States)

    Koppara, T; Virmani, R; Joner, M

    2015-02-01

    Drug-eluting stents are currently used in the majority of percutaneous coronary interventions. Preclinical investigations and human autopsy studies have shown that the high efficacy of drug-eluting stents (DES) in preventing restenosis is achieved at the expense of a delay in healing. Optical coherence tomography (OCT) represents a novel intracoronary imaging tool to evaluate vascular healing response after stent implantation. Owing to its outstanding resolution in the catheter near-field, quantitative morphometric measures were complemented by more qualitative description of neointimal tissue characterization. Clinical imaging studies employing these methodologies gained valuable insights into vascular healing responses after DES implantation and are reported in this review. However, an important limitation of OCT imaging analysis, despite its high resolution, remains the inability to assess the precise cellular composition and functional capability of the neointimal tissue, especially of the endothelium. Future long-term clinical studies are warranted to determine the clinical relevance of surrogate parameters derived from preliminary OCT surveillance studies. PMID:25566936

  13. 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

  14. Process monitoring of additive manufacturing by using optical tomography

    Science.gov (United States)

    Zenzinger, Guenter; Bamberg, Joachim; Ladewig, Alexander; Hess, Thomas; Henkel, Benjamin; Satzger, Wilhelm

    2015-03-01

    Parts fabricated by means of additive manufacturing are usually of complex shape and owing to the fabrication procedure by using selective laser melting (SLM), potential defects and inaccuracies are often very small in lateral size. Therefore, an adequate quality inspection of such parts is rather challenging, while non-destructive-techniques (NDT) are difficult to realize, but considerable efforts are necessary in order to ensure the quality of SLM-parts especially used for aerospace components. Thus, MTU Aero Engines is currently focusing on the development of an Online Process Control system which monitors and documents the complete welding process during the SLM fabrication procedure. A high-resolution camera system is used to obtain images, from which tomographic data for a 3dim analysis of SLM-parts are processed. From the analysis, structural irregularities and structural disorder resulting from any possible erroneous melting process become visible and may be allocated anywhere within the 3dim structure. Results of our optical tomography (OT) method as obtained on real defects are presented.

  15. 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.

  16. Optical coherence tomography: clinical applications in medical practice.

    Science.gov (United States)

    Al-Mujaini, Abdullah; Wali, Upender K; Azeem, Sitara

    2013-03-01

    Optical Coherence Tomography (OCT) is a success story of scientific and technological co-operation between a physicist and a clinician. The concept of cross-sectional imaging revolutionalized the applicability of OCT in the medical profession. OCT is a non-contact, topographic, biomicroscopic device that provides high resolution, cross-sectional digital images of live biological tissues in vivo and in real time. OCT is based on the property of tissues to reflect and backscatter light involving low-coherence interferometry. The spatial resolution of as little as 3 microns or even less has allowed us to study tissues almost at a cellular level. Overall, OCT is an invaluable adjunct in the diagnosis and follow up of many diseases of both anterior and posterior segments of the eye, primarily or secondary to systemic diseases. The digitalization and advanced software has made it possible to store and retrieve huge patient data for patient services, clinical applications and academic research. OCT has revolutionized the sensitivity and specificity of diagnosis, follow up and response to treatment in almost all fields of clinical practice involving primary ocular pathologies and secondary ocular manifestations in systemic diseases like diabetes mellitus, hypertension, vascular and neurological diseases, thus benefitting non-ophthalmologists as well. Systemically, OCT is proving to be a helpful tool in substantiating early diagnosis in diseases like multiple sclerosis and drug induced retinopathies by detecting early changes in morphology of the retinal nerve fiber layer. PMID:23599874

  17. Monitoring remineralization of enamel subsurface lesions by optical coherence tomography

    Science.gov (United States)

    Mandurah, Mona M.; Sadr, Alireza; Shimada, Yasushi; Kitasako, Yuichi; Nakashima, Syozi; Bakhsh, Turki A.; Tagami, Junji; Sumi, Yasunori

    2013-04-01

    Optical coherence tomography (OCT) is a potential clinical tool for enamel lesion monitoring. Swept-source OCT findings were compared with cross-sectional nanohardness findings of enamel. Subsurface bovine enamel lesions in three groups were subjected to (1) deionized water (control), (2) phosphoryl oligosaccharide of calcium (POs-Ca) or (3) POs-Ca with 1 ppm fluoride for 14 days. B-scans images were obtained at 1310-nm center wavelength on sound, demineralized and remineralized areas after 4, 7, and 14 days. The specimens were processed for cross-sectional nanoindentation. Reflectivity from enamel that had increased with demineralization decreased with remineralization. An OCT attenuation coefficient parameter (?t), derived based on the Beer-Lambert law as a function of backscatter signal slope, showed a strong linear regression with integrated nanohardness of all regions (p<0.001, r=-0.97). Sound enamel showed the smallest, while demineralized enamel showed the highest ?t. In group three, ?t was significantly lower at four days than baseline, but remained constant afterwards. In group two, the changes were rather gradual. There was no significant difference between groups two and three at 14 days in nanohardness or ?t POs-Ca with fluoride-enhanced nanohardness of the superficial zone. OCT signal attenuation demonstrated a capability for monitoring changes of enamel lesions during remineralization.

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

    DEFF Research Database (Denmark)

    Willerslev, Anne; Li, Xiao Qiang

    2014-01-01

    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.

  19. Automatic segmentation of anterior segment optical coherence tomography images

    Science.gov (United States)

    Williams, Dominic; Zheng, Yalin; Bao, Fangjun; Elsheikh, Ahmed

    2013-05-01

    Optical coherence tomography (OCT) images can provide quantitative measurements of the eye's entire anterior segment. A new technique founded on a newly proposed level set-based shape prior segmentation model has been developed for automatic segmentation of the cornea's anterior and posterior boundaries. This technique comprises three major steps: removal of regions containing irrelevant structures and artifacts, estimation of the cornea's location using a thresholding technique, and application of the new level set-based shape prior segmentation model to improve segmentation. The performance of our technique is compared to previously developed methods for analysis of the cornea in 33 OCT images of normal eyes, whereby manual annotations are used as a reference standard. The new technique achieves much improved concordance than previous methods, with a mean Dice's similarity coefficient of >0.92. This demonstrates the technique's potential to provide accurate and reliable measurements of the anterior segment geometry, which is important for many applications, including the construction of representative numerical simulations of the eye's mechanical behavior.

  20. Three-dimensional radiation dosimetry with optical projection tomography

    Science.gov (United States)

    Papadakis, A. E.; Zacharakis, G.; Ripoll, J.; Zacharopoulou, F.; Maris, T. G.; Damilakis, J.

    2009-05-01

    Here we present initial results on the study of the dosimetric properties of a normoxic N-Vinylpyrrolidone based polymer gel dosimeter using a newly developed optical projection tomography (OPT) system. The system employs a sensitive CCD camera, a rotation stage allowing full 360 deg rotation and a wide field homogeneous light source which transilluminates the gel sample. This setup is capable of producing high resolution images of the light attenuation map inside the sample's volume in three dimensions (3D). The experimental procedure involves the capturing of two-dimensional projection images of the polymer sample in rotation steps of 1 deg. Data analysis is performed by back projecting the photons using an inverse Radon transform resulting in the reconstruction of 3D images of the attenuation coefficient. The resulting 3D attenuation map of the irradiated volume can be directly correlated to the radiation dose imparted. The OPT system may operate in 'dry' conditions without the use of any refractive index matching fluids. The sensitivity and dynamic range offered by the methodology covers the range of radiotherapy doses in modern clinical practice.

  1. 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.

  2. Optical coherence tomography for nondestructive evaluation of fuel rod degradation

    Science.gov (United States)

    Renshaw, Jeremy B.; Jenkins, Thomas P.; Buckner, Benjamin D.; Friend, Brian

    2015-03-01

    Nuclear power plants regularly inspect fuel rods to ensure safe and reliable operation. Excessive corrosion can cause fuel failures which can have significant repercussions for the plant, including impacts on plant operation, worker exposure to radiation, and the plant's INPO rating. While plants typically inspect for fuel rod corrosion using eddy current techniques, these techniques have known issues with reliability in the presence of tenacious, ferromagnetic crud layers that can deposit during operation, and the nondestructive evaluation (NDE) inspection results can often be in error by a factor of 2 or 3. For this reason, alternative measurement techniques, such as Optical Coherence Tomography (OCT), have been evaluated that are not sensitive to the ferromagnetic nature of the crud. This paper demonstrates that OCT has significant potential to characterize the thickness of crud layers that can deposit on the surfaces of fuel rods during operation. Physical trials have been performed on simulated crud samples, and the resulting data show an apparent correlation between the crud layer thickness and the OCT signal.

  3. 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.

  4. Simultaneous dual-band optical coherence tomography for endoscopic applications

    Science.gov (United States)

    Xu, Jianbing; Yu, Luoqin; Wei, Xiaoming; Wang, Xie; Chui, Po Ching; Chan, Kin Tak; Lam, Edmund Y.; Lee, Nikki P.; Wong, Kenneth K. Y.

    2014-12-01

    Dual-band optical coherence tomography (OCT) can greatly enhance the imaging contrast with potential applications in functional (spectroscopic) analysis. A new simultaneous dual-band Fourier domain mode-locked swept laser configuration for dual-band OCT is reported. It was based on a custom-designed dual-channel driver to synchronize two different wavelength bands at 1310 and 1550 nm, respectively. Two lasing wavelengths were swept simultaneously from 1260 to 1364.8 nm for the 1310-nm band and from 1500 to 1604 nm for the 1550-nm band at an A-scan rate of 45 kHz. Broadband wavelength-division multiplexing was utilized to couple two wavelength bands into a common catheter for circumferential scanning to form dual-band OCT. The proposed dual-band OCT scheme was applied to endoscopic OCT imaging of mouse esophageal wall ex vivo and human fingertip in vivo to justify the feasibility of the proposed imaging technique. The proposed dual-band OCT system is fast and easy to be implemented, which allows for in vivo high-speed biomedical imaging with potential applications in spectroscopic investigations for endoscopic imaging.

  5. Polarization sensitive spectroscopic optical coherence tomography for multimodal imaging

    Science.gov (United States)

    Str?kowski, Marcin R.; Kraszewski, Maciej; Str?kowska, Paulina; Trojanowski, Micha?

    2015-03-01

    Optical coherence tomography (OCT) is a non-invasive method for 3D and cross-sectional imaging of biological and non-biological objects. The OCT measurements are provided in non-contact and absolutely safe way for the tested sample. Nowadays, the OCT is widely applied in medical diagnosis especially in ophthalmology, as well as dermatology, oncology and many more. Despite of great progress in OCT measurements there are still a vast number of issues like tissue recognition or imaging contrast enhancement that have not been solved yet. Here we are going to present the polarization sensitive spectroscopic OCT system (PS-SOCT). The PS-SOCT combines the polarization sensitive analysis with time-frequency analysis. Unlike standard polarization sensitive OCT the PS-SOCT delivers spectral information about measured quantities e.g. tested object birefringence changes over the light spectra. This solution overcomes the limits of polarization sensitive analysis applied in standard PS-OCT. Based on spectral data obtained from PS-SOCT the exact value of birefringence can be calculated even for the objects that provide higher order of retardation. In this contribution the benefits of using the combination of time-frequency and polarization sensitive analysis are being expressed. Moreover, the PS-SOCT system features, as well as OCT measurement examples are presented.

  6. Image reconstruction in optical tomography using Radon transform and its inverse

    Science.gov (United States)

    Petrehus, Viorel; Gavrila, Camelia; Gruia, Ion

    2009-10-01

    Optical tomography is a new medical imaging modality that is at the threshold of realization. A large amount of clinical work has shown the very real benefits that such a method could provide. At the same time a considerable effort has been put into theoretical studies of its probable success. At present there exist gaps between these two realms. In this paper we review some general approaches to inverse problems to set the context for optical tomography. An essential requirement is to treat the problem in a nonlinear fashion, by using an iterative method. The inverse problem is approached by numerical solutions methods using MathCad program. The Radon transform is the basic tool of the computerized tomography. In the sequel we introduce this transform, review some properties and present a numerical program for its inversion. We show some results that represent the most complex and realistic simulations of optical tomography yet developed.

  7. Preperimetric glaucoma diagnosis by confocal scanning laser tomography of the optic disc

    OpenAIRE

    Mardin, C.; Horn, F; Jonas, J; Budde, W.

    1999-01-01

    AIM—To evaluate the ability of confocal scanning laser tomography of the optic nerve head to detect glaucomatous optic nerve damage in ocular hypertensive eyes without visual field defects.?METHODS—The study included 50 normal subjects, 61 glaucoma patients with glaucomatous changes in the optic disc and visual field, and 102 "preperimetric" patients with increased intraocular pressure, normal visual fields, and glaucomatous appearance of the optic disc as evaluated on colour stereo ...

  8. Laser scanning tomography of the optic nerve head in ocular hypertension and glaucoma

    OpenAIRE

    Hatch, W; Flanagan, J; Etchells, E.; Williams-Lyn, D.; Trope, G.

    1997-01-01

    BACKGROUND—This study evaluated the ability of laser scanning tomography to distinguish between normal and glaucomatous optic nerve heads, and between glaucomatous subjects with and without field loss.?METHODS—57 subjects were classified into three diagnostic groups: subjects with elevated intraocular pressure, normal optic nerve heads, and normal visual fields (n=10); subjects with glaucomatous optic neuropathy and normal visual fields (n=30); and subjects with glaucomatous optic neuro...

  9. Dynamic contrast-enhanced diffuse optical tomography (DCE-DOT): experimental validation with a dynamic phantom

    OpenAIRE

    Unlu, Mehmet Burcin; Lin, Yuting; Gulsen, Gultekin

    2009-01-01

    Dynamic contrast-enhanced diffuse optical tomography (DCE-DOT) can provide spatially resolved enhancement kinetics of an optical contrast agent. We undertook a systematic phantom study to evaluate the effects of the geometrical parameters such as the depth and size of the inclusion as well as the optical parameters of the background on the recovered enhancement kinetics of the most commonly used optical contrast agent, indocyanine green (ICG). For this purpose a computer-controlled dynamic ph...

  10. Common-Path Optical Coherence Tomography for Biomedical Imaging and Sensing

    OpenAIRE

    Kang, Jin U.; Han, Jae-ho; Liu, Xuan; Zhang, Kang

    2010-01-01

    This paper describes a development of a fiber optic common-path optical coherence tomography (OCT) based imaging and guided system that possess ability to reliably identify optically transparent targets that are on the micron scale; ability to maintain a precise and safe position from the target; ability to provide spectroscopic imaging; ability to imaging biological target in 3-D. The system is based on a high resolution fiber optic Common-Path OCT (CP-OCT) that can be integrated into variou...

  11. «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 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.

  12. 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.

  13. 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.

  14. Platinum microheater integrated silicon optical bench assembly for endoscopic optical coherence tomography

    International Nuclear Information System (INIS)

    A novel platinum microheater and comb isolator integrated silicon optical bench (SiOB) assembly method has been successfully demonstrated to provide electrical connection and high precision alignment for a two-axis gimbal-less micromirror. Localized heating and wetting of plastic core micro solder balls is achieved by the integrated platinum heater, and the maximum measured temperature of the platinum heater is about 250 °C. In addition, assembly procedures are significantly simplified by involving a comb isolator made by deep reactive ion etching (DRIE) in comparison with our previously reported design. DRIE is also applied to form a 45° trench on the lower silicon substrate with a nearly vertical sidewall for the micromirror. Hence, the overall dimensions of the SiOB assembly can be reduced further to meet the requirements of endoscopic optical coherence tomography (EOCT) for miniaturization

  15. 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.

  16. 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,

  17. Retinal neurodegeneration on optical coherence tomography and cerebral atrophy.

    Science.gov (United States)

    Ong, Yi-Ting; Hilal, Saima; Cheung, Carol Y; Venketasubramanian, Narayanaswamy; Niessen, Wiro J; Vrooman, Henri; Anuar, Ainur R; Chew, Merwyn; Chen, Christopher; Wong, Tien Yin; Ikram, Mohammad Kamran

    2015-01-01

    Neurodegeneration in dementia is mainly evaluated by assessing cerebral atrophy, while retinal neurodegeneration can be quantified in vivo using optical coherence tomography (OCT). We examined the association of retinal nerve fibre layer (RNFL) and ganglion cell-inner plexiform layer (GC-IPL) thinning with global and regional cerebral atrophy on magnetic resonance imaging (MRI). Malay participants aged 60-80 years from the Epidemiology of Dementia in Singapore Study underwent comprehensive examinations, including 3-Tesla cranial MRI. RNFL and GC-IPL thicknesses were obtained from spectral domain-OCT; and cerebral grey and white matter volumes were obtained from MRI scans using a validated segmentation tool. Linear regression models were constructed with adjustment for age and sex; and additionally for vascular risk factors and MRI markers including intracranial volume. 164 participants without glaucoma with gradable quality MRI and OCT scans were included for analysis. GC-IPL thinning was associated with reduction in total brain volume in the occipital (mean change in GC-IPL per standard deviation (SD) decrease in occipital lobe volume: -1.77 ?m, 95% confidence interval (CI) -6.55 to 0.01 ?m) and temporal lobes (mean change in GC-IPL per SD decrease in temporal lobe volume: -3.45 ?m, 95%CI -5.40 to -1.49 ?m) in multivariate adjusted models. In particular, GC-IPL thinning was primarily associated with grey matter volume, whereas no association was found with white matter changes. Retinal neuronal damage, as reflected by GC-IPL thinning, was independently associated with grey matter loss in the occipital and temporal lobes, suggesting that retinal OCT may provide insights for assessing neurodegeneration in the brain. PMID:25451722

  18. 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)

  19. Optical coherence tomography for imaging of chronic total occlusions

    Science.gov (United States)

    Munce, Nigel R.; Yang, Victor X. D.; Qiang, Beiping; Courtney, Brian K.; Brzozowski, Lukasz; Bakueva, Ludmilla; Mao, Linda Y.; Standish, Beau; Butany, Jagdish; Dick, Alexander J.; Strauss, Bradley H.; Wright, Graham A.; Vitkin, Alex

    2005-09-01

    Chronic total occlusions (CTOs) are defined as complete occlusions of an artery older than one month. Minimally invasive catheter-based interventions commonly employed for partial occlusions (e.g., balloon angioplasty followed by stenting) are problematic in CTOs because of the phycisian's inability to pass the device through the occlusion without a significant risk of arterial wall perforations. Furthermore, successfully treated CTOs exhibit a high re-occlusion rate. As a result, these cases are mostly sent to bypass surgery. With the advent of drug-eluting stents that reduce the incidence of re-occlusion, and thus, eliminating the second problem, new devices have begun to emerge that aim to recanalize CTOs without the cost and trauma of bypass surgery. These devices, however, need effective image guidance methods to ensure successful crossing of the CTOs. Optical coherence tomography (OCT) is being evaluated as an intravascular imaging modality for guiding catheter-based interventions of CTOs. Occluded ex vivo human arterial samples were used to produce longitudinal cross-sections using an OCT system. These OCT images were compared with histology to assess OCT's ability to identify different components of the occluded artery, evaluate the imaging depth, and determine the ability to detect the underlying vessel wall. Given the inherent difficulties of creating a mechanically scanning OCT probe in the distal tip of a catheter for use in a stenotic artery, we directed our initial efforts towards developing a "motionless" fiber based OCT system using a single mode fiber array. We discuss design considerations for implementing a forward viewing intravascular OCT probe.

  20. 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 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.

  1. Optical coherence tomography for guidance in bifurcation lesion treatment.

    Science.gov (United States)

    Di Mario, Carlo; Iakovou, Ioannis; van der Giessen, Wim J; Foin, Nicolas; Adrianssens, Tom; Tyczynski, Pawel; Ghilencea, Liviu; Viceconte, Nicola; Lindsay, Alistair C

    2010-12-01

    Optical coherence tomography (OCT) has higher resolution than IVUS (approximately 10 times), with the potential to precisely measure lumen diameters in the variable geometry of a bifurcational lesion and to identify superficial lipid laden plaques and calcium, relevant to confirm the severity of the lumen obstruction before treatment and guide location and diameter of the stent. In addition, OCT produces fewer strut-induced artifacts and offers precise evaluation of strut apposition in a real-life clinical setting. The increase in the speed of image acquisition consequent to the introduction of frequency domain OCT allows rapid pull-back at a speed of 2 cm/sec, minimising the amount of contrast required to clear blood during image acquisition, with an average injection of 10-18 ml required for the maximal length currently available of 5.6 cm. This allows serial OCT acquisitions, typically before treatment if the lesion is not very severe and flow is expected to be present around the OCT catheter, after predilatation and to assess and guide stent expansion. Repeated OCT examinations at follow-up may help to detect presence and characteristics of strut coverage, a potential predictor of late stent thrombosis. These applications are of particular interest in the context of bifurcational lesion treatment because this condition is still associated with a higher number of malapposed stent struts and frequent impairment of stent expansion, explaining the higher incidence of stent thrombosis and restenosis. In this article, all potential applications of OCT for bifurcational lesion treatment are explored. The use of OCT to characterise plaque components, and to optimise stent expansion and strut apposition are first discussed in detail. The conclusion of the article highlights some future research and technological developments that promise to expand the role of OCT further still. PMID:21930500

  2. Validation of optical coherence tomography in vivo using cryostat histology

    International Nuclear Information System (INIS)

    We aimed to validate for the first time optical coherence tomography (OCT) measurements of epidermal thickness (ET) using cryopreparation for histology. OCT assessments of ET were performed on healthy skin using the algorithms as follows: first, peak-to-valley analysis of the A-scan (ET-OCT-V), second, line-traced image analysis of the B-scan (ET-OCT-IA). Histology was performed using cryostat sections which were also evaluated using the image analysis (ET-Histo). We selected 114 samples, including B-scans and corresponding histology, for method comparison between ET-OCT-IA and ET-Histo. Forty-two A-scans were available for method comparison between ET-OCT-V and ET-Histo. Bland and Altman plots revealed a marked bias with wide 95% limits of agreement for ET-OCT-V versus ET-Histo. Comparison of ET-OCT-IA versus ET-Histo revealed only a slight bias and narrow 95% limits of agreement. A-scan analysis for ET determination is linked to significant limitations and lacks agreement with histology. By contrast, we observed satisfactory agreement between ET-OCT-IA and ET-Histo indicating that both methods can be utilized interchangeably. OCT using the line-traced image analysis of the B-scan appears to be a valid and relatively practicable method for the determination of ET in vivo. Furthermore, the comparisons with the in vivo OCT profiles demonstrate that cryostat sectioning provides a better preservation of relative and absolute dimensions of skin layers than paraffin embeddnsions of skin layers than paraffin embedding. (note)

  3. 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

  4. Biophotonic sensors on a silicon chip for Raman spectroscopy and optical coherence tomography

    Science.gov (United States)

    Pollnau, Markus; Ismail, Nur; Akca, B. Imran; Wörhoff, Kerstin; de Ridder, René M.

    2012-01-01

    We review our recent results on integrating biomedical optical systems onto a silicon chip. Light collection by integrated waveguides has been investigated. Confocal light delivery and collection by a combination of two arrayed-waveguide gratings has been achieved. Using an arrayed-waveguide grating as an integrated spectrometer, Raman spectroscopy and spectral-domain optical coherence tomography have been demonstrated.

  5. Phase-resolved optical coherence tomography and optical Doppler tomography for imaging blood flow in human skin with fast scanning speed and high velocity sensitivity

    International Nuclear Information System (INIS)

    We have developed a novel phase-resolved optical coherence tomography (OCT) and optical Doppler tomography (ODT) system that uses phase information derived from a Hilbert transformation to image blood flow in human skin with fast scanning speed and high velocity sensitivity. Using the phase change between sequential scans to construct flow-velocity imaging, this technique decouples spatial resolution and velocity sensitivity in flow images and increases imaging speed by more than 2 orders of magnitude without compromising spatial resolution or velocity sensitivity. The minimum flow velocity that can be detected with an axial-line scanning speed of 400 Hz and an average phase change over eight sequential scans is as low as 10 ?m/s , while a spatial resolution of 10 ?m is maintained. Using this technique, we present what are to our knowledge the first phase-resolved OCT/ODT images of blood flow in human skin. (c) 2000 Optical Society of America

  6. Imaging patients with glaucoma using spectral-domain optical coherence tomography and optical microangiography

    Science.gov (United States)

    Auyeung, Kris; Auyeung, Kelsey; Kono, Rei; Chen, Chieh-Li; Zhang, Qinqin; Wang, Ruikang K.

    2015-03-01

    In ophthalmology, a reliable means of diagnosing glaucoma in its early stages is still an open issue. Past efforts, including forays into fluorescent angiography (FA) and early optical coherence tomography (OCT) systems, to develop a potential biomarker for the disease have been explored. However, this development has been hindered by the inability of the current techniques to provide useful depth and microvasculature information of the optic nerve head (ONH), which have been debated as possible hallmarks of glaucoma progression. We reasoned that a system incorporating a spectral-domain OCT (SD-OCT) based Optical Microangiography (OMAG) system, could allow an effective, non-invasive methodology to evaluate effects on microvasculature by glaucoma. SD-OCT follows the principle of light reflection and interference to produce detailed cross-sectional and 3D images of the eye. OMAG produces imaging contrasts via endogenous light scattering from moving particles, allowing for 3D image productions of dynamic blood perfusion at capillary-level resolution. The purpose of this study was to investigate the optic cup perfusion (flow) differences in glaucomatous and normal eyes. Images from three normal and five glaucomatous subjects were analyzed our OCT based OMAG system for blood perfusion and structural images, allowing for comparisons. Preliminary results from blood flow analysis revealed reduced blood perfusion within the whole-depth region encompassing the Lamina Cribrosa in glaucomatous cases as compared to normal ones. We conclude that our OCT-OMAG system may provide promise and viability for glaucoma screening.

  7. 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 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.

  8. 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.

  9. 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

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

    Science.gov (United States)

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

    2015-01-01

    AIM To determine angle closure agreements between gonioscopy and anterior segment optical coherence tomography (AS-OCT), as well as gonioscopy and spectral domain OCT (SD-OCT). A secondary objective was to quantify inter-observer agreements of AS-OCT and SD-OCT assessments. METHODS Seventeen consecutive subjects (33 eyes) were recruited from the study hospital's Glaucoma clinic. Gonioscopy was performed by a glaucomatologist masked to OCT results. OCT images were read independently by 2 other glaucomatologists masked to gonioscopy findings as well as each other's analyses of OCT images. RESULTS Totally 84.8% and 45.5% of scleral spurs were visualized in AS-OCT and SD-OCT images respectively (P<0.01). The agreement for angle closure between AS-OCT and gonioscopy was fair at k=0.31 (95% confidence interval, CI: 0.03-0.59) and k=0.35 (95% CI: 0.07-0.63) for reader 1 and 2 respectively. The agreement for angle closure between SD-OCT and gonioscopy was fair at k=0.21 (95% CI: 0.07-0.49) and slight at k=0.17 (95% CI: 0.08-0.42) for reader 1 and 2 respectively. The inter-reader agreement for angle closure in AS-OCT images was moderate at 0.51 (95% CI: 0.13-0.88). The inter-reader agreement for angle closure in SD-OCT images was slight at 0.18 (95% CI: 0.08-0.45). CONCLUSION Significant proportion of scleral spurs were not visualised with SD-OCT imaging resulting in weaker inter-reader agreements. Identifying other angle landmarks in SD-OCT images will allow more consistent angle closure assessments. Gonioscopy and OCT imaging do not always agree in angle closure assessments but have their own advantages, and should be used together and not exclusively. PMID:25938053

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

    Directory of Open Access Journals (Sweden)

    Elton Lik Tong Tay

    2015-04-01

    Full Text Available AIM: To determine angle closure agreements between gonioscopy and anterior segment optical coherence tomography (AS-OCT, as well as gonioscopy and spectral domain OCT (SD-OCT. A secondary objective was to quantify inter-observer agreements of AS-OCT and SD-OCT assessments. METHODS: Seventeen consecutive subjects (33 eyes were recruited from the study hospital’s Glaucoma clinic. Gonioscopy was performed by a glaucomatologist masked to OCT results. OCT images were read independently by 2 other glaucomatologists masked to gonioscopy findings as well as each other’s analyses of OCT images. RESULTS: Totally 84.8% and 45.5% of scleral spurs were visualized in AS-OCT and SD-OCT images respectively (P<0.01. The agreement for angle closure between AS-OCT and gonioscopy was fair at k=0.31 (95% confidence interval, CI: 0.03-0.59 and k=0.35 (95% CI: 0.07-0.63 for reader 1 and 2 respectively. The agreement for angle closure between SD-OCT and gonioscopy was fair at k=0.21 (95% CI: 0.07-0.49 and slight at k=0.17 (95% CI: 0.08-0.42 for reader 1 and 2 respectively. The inter-reader agreement for angle closure in AS-OCT images was moderate at 0.51 (95% CI: 0.13-0.88. The inter-reader agreement for angle closure in SD-OCT images was slight at 0.18 (95% CI: 0.08-0.45. CONCLUSION: Significant proportion of scleral spurs were not visualised with SD-OCT imaging resulting in weaker inter-reader agreements. Identifying other angle landmarks in SD-OCT images will allow more consistent angle closure assessments. Gonioscopy and OCT imaging do not always agree in angle closure assessments but have their own advantages, and should be used together and not exclusively.

  12. On forward and inverse models in optical tomography

    OpenAIRE

    Schlottbom, Matthias

    2011-01-01

    Die vorliegende Arbeit beschäftigt sich mit Vorwärts- und Rückwärtsmodellen in der optischen Tomographie. Mit optischer Tomographie wird ein nicht-invasives bildgebendes Verfahren bezeichnet, bei dem biologisches Gewebe mit Hilfe von Licht im nah-infraroten Bereich durchleuchtet wird, um qualitative oder quantitative Informationen über optische Eigenschaften des Gewebes zu erlangen. Die Ausbreitung von Licht in solchen Geweben wird weithin mit der (zeitharmonischen) monochromatischen Str...

  13. Performance of megahertz amplified optical time-stretch optical coherence tomography (AOT-OCT).

    Science.gov (United States)

    Xu, Jingjiang; Wei, Xiaoming; Yu, Luoqin; Zhang, Chi; Xu, Jianbing; Wong, K K Y; Tsia, Kevin K

    2014-09-22

    Enabled by the ultrahigh-speed all-optical wavelength-swept mechanism and broadband optical amplification, amplified optical time-stretch optical coherence tomography (AOT-OCT) has recently been demonstrated as a practical alternative to achieve ultrafast A-scan rate of multi-MHz in OCT. With the aim of identifying the optimal scenarios for MHz operation in AOT-OCT, we here present a theoretical framework to evaluate its performance metric. In particular, the analysis discusses the unique features of AOT-OCT, such as its superior coherence length, and the relationship between the optical gain and the A-scan rate. More importantly, we evaluate the sensitivity of AOT-OCT in the MHz regime under the influence of the amplifier noise. Notably, the model shows that AOT-OCT is particularly promising when operated at the A-scan rate well beyond multi-MHz--not trivially achievable by any existing swept-source OCT platform. A sensitivity beyond 90 dB, close to the shot-noise limit, can be maintained in the range of 2 - 10 MHz with an optical net gain of ~10 dB. Experimental measurement also shows excellent agreement with the theoretical prediction. While distributed fiber Raman amplification is mainly considered in this paper, the theoretical model is generally applicable to any type of amplification schemes. As a result, our analysis serves as a useful tool for further optimization of AOT-OCT system--as a practical alternative to enable MHz OCT operation. PMID:25321720

  14. Polarization maintaining fiber based ultra-high resolution spectral domain polarization sensitive optical coherence tomography

    OpenAIRE

    Götzinger, Erich; Baumann, Bernhard; Pircher, Michael; Hitzenberger, Christoph K.

    2009-01-01

    We present a new ultra high resolution spectral domain polarization sensitive optical coherence tomography (PS-OCT) system based on polarization maintaining (PM) fibers. The method transfers the principles of our previous bulk optic PS-OCT systems to a fiberized setup. The phase shift between the orthogonal polarization states travelling in the two orthogonal modes of the PM fiber is compensated by software in post processing. Thereby, the main advantage of our bulk optics setups, i.e. the us...

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

    CERN Document Server

    Kushnir, O; Vlokh, R; Kukhtarev, N

    2005-01-01

    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 components are ascertained for the case of weak optical anisotropy.

  16. 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.

  17. The Impact of Multifocal Intraocular Lens in Retinal Imaging with Optical Coherence Tomography

    OpenAIRE

    Dias-Santos, A; Costa, L.; Lemos, V; Anjos, R; Vicente, A; Ferreira, J; Cunha, JP

    2015-01-01

    Multifocal intraocular lenses (MF IOLs) have concentric optical zones with different dioptric power, enabling patients to have good visual acuity at multiple focal points. However, several optical limitations have been attributed to this particular design. The purpose of this study is to access the effect of MF IOLs design on the accuracy of retinal optical coherence tomography (OCT). Cross-sectional study conducted at the Refractive Surgery Department of Central Lisbon Hospital Center. Twent...

  18. Optical coherence tomography predicts visual outcome for pituitary tumors.

    Science.gov (United States)

    Danesh-Meyer, Helen V; Wong, Aaron; Papchenko, Taras; Matheos, Kaliopy; Stylli, Stanley; Nichols, Andrew; Frampton, Chris; Daniell, Mark; Savino, Peter J; Kaye, Andrew H

    2015-07-01

    We evaluate if the relationship between optical coherence tomography (OCT) of the retinal nerve fibre layer (RNFL) and visual outcome continued over long-term visual recovery in 107 patients undergoing pituitary decompression. Recently, it has been recognized that OCT of the RNFL has prognostic value in predicting visual outcomes after surgery for chiasmal compression caused by pituitary tumours. Patients were followed up at three time points: pre-operative (visit 1), 6-10weeks post-operative (visit 2) and 9-15months follow-up (visit 3). We found that patients with thin pre-operative RNFL had more severe visual field defects (mean deviation [MD] -9.22 versus -3.96 decibels [dB]; p=0.001), but pre-operative visual acuity (VA) was good in both normal and thin RNFL groups (Snellen VA 6/5 and 6/4; p=0.039). For those with thin RNFL the greatest improvement was between visit 2 and 3 (MD -7.1dB versus -3.4dB, respectively; p<0.001) compared with pre-operative -9.8dB. Normal RNFL patients showed greatest improvement between visits 1 and 2 (pre-operative -4.8dB, visit 2 -2.0dB, visit 3 -0.9dB; p=0.001). For long-term follow-up, 81.0% of eyes with normal RNFL, compared to 37.1% with thin RNFL (p<0.001), achieved an MD of -2.00dB (final visit). At final follow-up, 97.5% of normal RNFL eyes achieved VA of 6/12 or better compared with 88.2% with thin RNFL (p=0.034). Our results indicate that long-term visual recovery after surgical decompression of pituitary lesions is predicted by pre-operative OCT RNFL. Patients with normal RNFL thickness show an increased propensity for visual recovery. This effect continues after long-term follow-up, however, most visual recovery occurs within the first 6-10weeks. PMID:25891894

  19. Evaluation of calcification of a hydrogel intraocular lens by optical coherence tomography.

    Science.gov (United States)

    Hatou, Shin; Inoue, Makoto; Kurosaka, Daijiro; Hida, Yudi Richard; Shinoda, Kei; Oguchi, Yoshihisa

    2004-07-01

    We describe 2 cases of calcification of hydrogel intraocular lenses (IOLs) evaluated by optical coherence tomography. Dense or slight surface opacities of hydrogel IOLs were detected initially by slitlamp biomicroscopy in a 55-year-old woman and a 77-year-old woman. The opacities resulted in complaints of hazy vision after uneventful phacoemulsification and IOL implantation. Optical coherence tomography was used to further assess the opacities and showed calcification by high reflectivity on the anterior and posterior IOL surfaces in the first patient and on the anterior surface in the second patient. No abnormal reflectivity was seen on the surface of a hydrophobic acrylic IOL in the second patient's fellow eye. Optical coherence tomography may be useful to detect calcification of a hydrogel IOL. PMID:15210245

  20. Optical coherence tomography and optical coherence domain reflectometry for deep brain stimulation probe guidance

    Science.gov (United States)

    Jeon, Sung W.; Shure, Mark A.; Baker, Kenneth B.; Chahlavi, Ali; Hatoum, Nagi; Turbay, Massud; Rollins, Andrew M.; Rezai, Ali R.; Huang, David

    2005-04-01

    Deep Brain Stimulation (DBS) is FDA-approved for the treatment of Parkinson's disease and essential tremor. Currently, placement of DBS leads is guided through a combination of anatomical targeting and intraoperative microelectrode recordings. The physiological mapping process requires several hours, and each pass of the microelectrode into the brain increases the risk of hemorrhage. Optical Coherence Domain Reflectometry (OCDR) in combination with current methodologies could reduce surgical time and increase accuracy and safety by providing data on structures some distance ahead of the probe. For this preliminary study, we scanned a rat brain in vitro using polarization-insensitive Optical Coherence Tomography (OCT). For accurate measurement of intensity and attenuation, polarization effects arising from tissue birefringence are removed by polarization diversity detection. A fresh rat brain was sectioned along the coronal plane and immersed in a 5 mm cuvette with saline solution. OCT images from a 1294 nm light source showed depth profiles up to 2 mm. Light intensity and attenuation rate distinguished various tissue structures such as hippocampus, cortex, external capsule, internal capsule, and optic tract. Attenuation coefficient is determined by linear fitting of the single scattering regime in averaged A-scans where Beer"s law is applicable. Histology showed very good correlation with OCT images. From the preliminary study using OCT, we conclude that OCDR is a promising approach for guiding DBS probe placement.

  1. High-sensitive full-range optical vibrometry based on Fourier-domain optical coherence tomography

    Science.gov (United States)

    Subhash, Hrebesh M.; Leahy, Martin

    2014-03-01

    Optical vibrometery based on low coherence Fourier-domain optical coherence tomography (FD-OCT) technique are well capable for providing depth resolved vibration information in comparison with conventional laser based vibrometery. Recently, there has been growing interest in developing coherence-domain vibrometry for various clinical and pre-clinical applications. However, a major drawback of the conventional vibrometer based on Fourier-domain low coherence interferometry is the complex-conjugate ambiguity. This is because in FD-OCT, the detected real valued spectral interferogram is Fourier transformed to localize the scatter within the sample. The Fourier transform of a real valued function is Hermitian, so the reconstructed image is symmetric with respect to the zero-phase delay of the interferometer, leading to ambiguity in interpretation of the resulted OCT images. In this paper, we introduce a full range optical coherence vibrometry to utilize the whole imaging range of the spectrometer. The mirror image elimination is based on the linear phase modulation of the interferometer's reference arm mirror and with an algorithm that exploits Hilbert transform to obtain full range complex imaging.

  2. Laser-ablated silicon nanoparticles: optical properties and perspectives in optical coherence tomography

    Science.gov (United States)

    Kirillin, M. Yu; Sergeeva, E. A.; Agrba, P. D.; Krainov, A. D.; Ezhov, A. A.; Shuleiko, D. V.; Kashkarov, P. K.; Zabotnov, S. V.

    2015-07-01

    Due to their biocompatibility silicon nanoparticles have high potential in biomedical applications, especially in optical diagnostics. In this paper we analyze properties of the silicon nanoparticles formed via laser ablation in water and study the possibility of their application as contrasting agents in optical coherence tomography (OCT). The nanoparticles suspension was produced by picosecond laser irradiation of monocrystalline silicon wafers in water. According to transmission electron microcopy analysis the silicon nanoparticles in the obtained suspension vary in size from 2 to 200?nm while concentration of the particles is estimated as 1013cm?3. The optical properties of the suspension in the range from 400 to 1000?nm were studied by spectrophotometry measurements revealing a scattering coefficient of about 0.1?mm?1 and a scattering anisotropy factor in the range of 0.2–0.4. In OCT study a system with a central wavelength of 910?nm was employed. Potential of the silicon nanoparticles as a contrasting agent for OCT is studied in experiments with agarose gel phantoms. Topical application of the nanoparticles suspension allowed the obtaining of the contrast of structural features of phantom up to 14?dB in the OCT image.

  3. 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.

  4. High-performance multi-megahertz optical coherence tomography based on amplified optical time-stretch.

    Science.gov (United States)

    Xu, Jingjiang; Wei, Xiaoming; Yu, Luoqin; Zhang, Chi; Xu, Jianbing; Wong, K K Y; Tsia, Kevin K

    2015-04-01

    As the key prerequisite of high-speed volumetric structural and functional tissue imaging in real-time, scaling the A-scan rate beyond MHz has been one of the major pursuits in the development of optical coherence tomography (OCT). Along with a handful of techniques enabling multi-MHz, amplified optical time-stretch OCT (AOT-OCT) has recently been demonstrated as a viable alternative for ultrafast swept-source OCT well above MHz without the need for the mechanical wavelength-tuning mechanism. In this paper, we report a new generation of AOT-OCT demonstrating superior performance to its older generation and all other time-stretch-based OCT modalities in terms of shot-to-shot stability, sensitivity (~90dB), roll-off performance (>4 mm/dB) and A-scan rate (11.5 MHz). Such performance is mainly attributed to the combined contribution from the stable operation of the broadband and compact mode-locked fiber laser as well as the optical amplification in-line with the time-stretch process. The system allows us, for the first time, to deliver volumetric time-stretch-based OCT of biological tissues with the single-shot A-scan rate beyond 10 MHz. Comparing with the existing high-speed OCT systems, the inertia-free AOT-OCT shows promises to realize high-performance 3D OCT imaging at video rate. PMID:25909017

  5. Imaging-AOTF-based full-field spectral-domain optical coherence tomography

    Science.gov (United States)

    Machikhin, Alexander; Viskovatykh, Alexander; Pozhar, Vitold; Burmak, Ludmila

    2015-03-01

    A technique for spectral filtration of interference images in full-field optical coherence tomography is proposed, implemented and tested. It is based on the spectral selection of light in the registration channel of the interferometer by imaging acousto-optic tunable filter. It is demonstrated that the diffraction of two interfering optical beams via the same ultrasound wave does not destruct the coherence. This new technique, which can be named tunable-imaging-filter-based full-field spectral-domain optical coherence tomography (TIF FF SD OCT), is applicable for 3D surface and inner structure visualization of optically inhomogeneous biomedical objects with moderate spectral, lateral and axial resolution, however with rather high speed.

  6. Optical coherence tomography as a promising imaging tool for brain investigations.

    Science.gov (United States)

    Osiac, Eugen; B?l?eanu, Tudor-Adrian; C?t?lin, Bogdan; Mogoant?, Lauren?iu; Gheonea, Cristian; Dinescu, Sorin Nicolae; Albu, Carmen Valeria; Cotoi, Bogdan Virgil; Tica, Oana-Sorina; Sfredel, Veronica

    2014-01-01

    This paper will review the newest results and directions for the usage of optical coherence tomography as an imaging tool for brain studies, focusing mostly on a rodent model. Together with state of the art in the field, based on some of the most recent work, this paper will include a brief look on some results obtained by our group. Brain injuries and stroke data obtained by optical coherence tomography analyzing will be presented as a possibility of detection and evaluation for affected tissue, using this imaging system. PMID:25178320

  7. Spectral fractionation detection of gold nanorod contrast agents using optical coherence tomography.

    Science.gov (United States)

    Jia, Yali; Liu, Gangjun; Gordon, Andrew Y; Gao, Simon S; Pechauer, Alex D; Stoddard, Jonathan; McGill, Trevor J; Jayagopal, Ashwath; Huang, David

    2015-02-23

    We demonstrate the proof of concept of a novel Fourier-domain optical coherence tomography contrast mechanism using gold nanorod contrast agents and a spectral fractionation processing technique. The methodology detects the spectral shift of the backscattered light from the nanorods by comparing the ratio between the short and long wavelength halves of the optical coherence tomography signal intensity. Spectral fractionation further divides the halves into sub-bands to improve spectral contrast and suppress speckle noise. Herein, we show that this technique can detect gold nanorods in intralipid tissue phantoms. Furthermore, cellular labeling by gold nanorods was demonstrated using retinal pigment epithelial cells in vitro. PMID:25836459

  8. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Sakhalkar, H S [Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710 (United States); Dewhirst, M [Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710 (United States); Oliver, T [Department of Cell Biology, Duke University Medical Center, Durham, NC 27710 (United States); Cao, Y [Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710 (United States); Oldham, M [Department of Radiation Oncology Physics, and Biomedical Engineering, Duke University Medical Center, Durham, NC 27710 (United States)

    2007-04-21

    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. 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.

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

    International Nuclear Information System (INIS)

    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 sp 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

  12. Progress on developing wavefront sensorless adaptive optics optical coherence tomography for in vivo retinal imaging in mice

    Science.gov (United States)

    Zam, Azhar; Zhang, Pengfei; Jian, Yifan; Sarunic, Marinko V.; Bonora, Stefano; Pugh, Edward N.; Zawadzki, Robert J.

    2015-03-01

    We present a new design for a wavefront sensorless adaptive optics (WS-AO) Fourier domain optical coherence tomography (FD-OCT) system for small animal retinal imaging in vivo. Without the optical complications necessary for inclusion of a wavefront sensor in the optical system, this version of WS-AO FD-OCT system has a simplified optical design, including elimination of long focal length scanning optics and optical conjugation of vertical and horizontal scanners. This modification provides a modular large Field of View for retinal screening (25 degree visual angle), while also allowing a "zoom" capability for allocating all the scanning resources to a smaller region of interest, allowing high resolution aberration-corrected imaging. In the present system we used a 0 Dpt contact lens to stabilize the mouse eye position and to allow long duration imaging. Defocus (axial focus position) in our system is controlled by the collimation of the OCT sample arm entrance beam.

  13. 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.

  14. Computed tomography of the optic nerve with special reference to the attenuation values

    International Nuclear Information System (INIS)

    The value of computed tomography (CT) for ophthalmology needs no longer to be emphasized. Everything, however, has its limitations. In this article, the limitations of CT for the diagnosis of the optic nerve diameter were studied in an orbit-optic nerve model. The difference of 15 Hounsfield units between two scans which demonstrated the optic nerve having almost the same diameter, as a result of the partial volume effect, was obtained. This suggested that the attenuation values of the optic nerve are markedly influenced by the partial volume effect, and that they require further investigation for clinical use. (author)

  15. Applying LED in full-field optical coherence tomography for gastrointestinal endoscopy

    Science.gov (United States)

    Yang, Bor-Wen; Wang, Yu-Yen; Juan, Yu-Shan; Hsu, Sheng-Jie

    2015-05-01

    Optical coherence tomography (OCT) has become an important medical imaging technology due to its non-invasiveness and high resolution. Full-field optical coherence tomography (FF-OCT) is a scanning scheme especially suitable for en face imaging as it employs a CMOS/CCD device for parallel pixels processing. FF-OCT can also be applied to high-speed endoscopic imaging. Applying cylindrical scanning and a right-angle prism, we successfully obtained a 360° tomography of the inner wall of an intestinal cavity through an FF-OCT system with an LED source. The 10-?m scale resolution enables the early detection of gastrointestinal lesions, which can increase detection rates for esophageal, stomach, or vaginal cancer. All devices used in this system can be integrated by MOEMS technology to contribute to the studies of gastrointestinal medicine and advanced endoscopy technology.

  16. Acousto-optic tomography of tissues in the reflective and coaxial configuration

    Science.gov (United States)

    Fu, Hongbo; Xing, Da

    2005-01-01

    Ultrasound-modulated optical tomography is a noninvasive imaging technique for biomedical diagnosis. With this technique, an imaging system takes advantage of focused ultrasonic field to mark the photon trajectories in a biological sample by modulating the optical path in the focal zone. The tagged photon reflects the local optical and mechanical properties in the ultrasonic focal zone and permits tomographic imaging of biological tissues by scanning. Based on the high-sensitivity detection technique, we have developed a reflective and coaxial configuration, which was more convenient and hopeful to produce an easy-controlling setup for practical application. In addition, this configuration can bring a new method to improve the spatial resolution of the tomographic plane paralle to the ultrasonic axis in the traditional configuration. Optical tomographys of the biological tissue were successfully obtained experimentally.

  17. 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

  18. 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...

  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. Combined Raman spectroscopy and optical coherence tomography device for tissue characterization

    OpenAIRE

    Patil, Chetan A.; Bosschaart, Nienke; Keller, Matthew D.; Leeuwen, Ton G.; Mahadevan-jansen, Anita

    2008-01-01

    We report a dual-modal device capable of sequential acquisition of Raman spectroscopy (RS) and optical coherence tomography (OCT) along a common optical axis. The device enhances application of both RS and OCT by precisely guiding RS acquisition with OCT images while also compensating for the lack of molecular specificity in OCT with the biochemical specificity of RS. We characterize the system performance and demonstrate the capability to identify structurally ambiguous features within an OC...

  1. 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...

  2. Endoscopic Functional Fourier Domain Common Path Optical Coherence Tomography for Microsurgery

    OpenAIRE

    Kang, Jin U.; Han, Jae-ho; Liu, Xuan; Zhang, Kang; Song, Chul Gyu; Gehlbach, Peter

    2010-01-01

    A single-arm interferometer based optical coherence tomography (OCT) system known as common-path OCT (CPOCT) is rapidly progressing towards practical application. Due in part to the simplicity and robustness of its design, Fourier Domain CPOCT (FD-CP-OCT) offers advantages in many endoscopic sensing and imaging applications. FD-CP-OCT uses simple, interchangeable fiber optic probes that are easily integrated into small and delicate surgical tools. The system is capable of providing not only h...

  3. Fiber-Based Polarization Diversity Detection for Polarization-Sensitive Optical Coherence Tomography

    OpenAIRE

    Hamid Pahlevaninezhad; Lee, Anthony M. D.; Lucas Cahill; Stephen Lam; Calum MacAulay; Pierre Lane

    2014-01-01

    We present a new fiber-based polarization diversity detection (PDD) scheme for polarization sensitive optical coherence tomography (PSOCT). This implementation uses a new custom miniaturized polarization-maintaining fiber coupler with single mode (SM) fiber inputs and polarization maintaining (PM) fiber outputs. The SM fiber inputs obviate matching the optical lengths of the two orthogonal OCT polarization channels prior to interference while the PM fiber outputs ensure defined orthogonal axe...

  4. Acousto-optical coherence tomography with a digital holographic detection scheme

    OpenAIRE

    Benoit A La Guillaume, Emilie; Farahi, Salma; Bossy, Emmanuel; Gross, Michel; Ramaz, François

    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 a...

  5. Optical coherence tomography diagnostics for onco–urology. Review of clinical perspectives

    OpenAIRE

    Sergiy Kharchenko; Jan Adamowicz; Maciej Wojtkowski; Tomasz Drewa

    2013-01-01

    Introduction. Optical coherence tomography (OCT) is being investigated widely for use in urologic pathology. The current imaging of urogenital cancers cannot be perfect, thus, routine methods demands new updates or inventions of alternative radiological scope. OCT presents so–called “live” optical biopsy. The authors aim to review this modality for uro–oncological purposes.Matherial and methods. A series of 37 publications between 1989 and 2012 was selected and cited from GoogleSchola...

  6. Non contact fluorescence optical tomography by means of numerical and analytical approaches

    International Nuclear Information System (INIS)

    Numerical and analytical approaches for the forward solver used in noncontact continuous wave fluorescence optical tomography are considered. Experiments have been carried out on a half cylinder resin phantom with Alexa750 fluorophores inclusions to test the feasibility of these two approaches

  7. Optimizing magnetomotive contrast of SPIO-labeled platelets for thrombosis imaging in optical coherence tomography

    OpenAIRE

    Oldenburg, Amy L.; Spivak, Dmitry; Wu, Gongting; Tsui, Frank; Fischer, Thomas H.

    2012-01-01

    Rehydratable, lyophilized platelets loaded with superparamagnetic iron oxides (SPIOs) has the potential to provide magnetomotive imaging contrast to sites of vascular damage, including thrombosis complicating atherosclerosis and hemorrhage. Magnetomotive optical coherence tomography (MMOCT) contrasts SPIO-platelets based on their nanoscale, magnetically-induced motion. We report improvements in MMOCT imaging contrast and sensitivity by optimizing the magnetic properties and SPIO loading of th...

  8. 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.

  9. 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.

  10. Complete Two-dimensional Muellermetric Imaging of Biological Tissue Using Heterodyned Optical Coherence Tomography

    CERN Document Server

    Liu, Xue; Shahriar, M S

    2010-01-01

    A polarization-sensitive optical coherence tomography system based on heterodyning and filtering techniques is built to perform Stokesmetric imaging of different layers of depths in a porcine tendon sample. The complete 4\\times4 backscattering Muellermetric images of one layer are acquired using such a system. The images reveal information indiscernible from a conventional OCT system.

  11. Design and testing of prototype handheld scanning probes for optical coherence tomography.

    Science.gov (United States)

    Demian, Dorin; Duma, Virgil-Florin; Sinescu, Cosmin; Negrutiu, Meda Lavinia; Cernat, Ramona; Topala, Florin Ionel; Hutiu, Gheorghe; Bradu, Adrian; Podoleanu, Adrian Gh

    2014-08-01

    Three simple and low-cost configurations of handheld scanning probes for optical coherence tomography have been developed. Their design and testing for dentistry applications are presented. The first two configurations were built exclusively from available off-the-shelf optomechanical components, which, to the best of our knowledge, are the first designs of this type. The third configuration includes these components in an optimized and ergonomic probe. All the designs are presented in detail to allow for their duplication in any laboratory with a minimum effort, for applications that range from educational to high-end clinical investigations. Requirements that have to be fulfilled to achieve configurations which are reliable, ergonomic-for clinical environments, and easy to build are presented. While a range of applications is possible for the prototypes developed, in this study the handheld probes are tested ex vivo with a spectral domain optical coherence tomography system built in-house, for dental constructs. A previous testing with a swept source optical coherence tomography system has also been performed both in vivo and ex vivo for ear, nose, and throat-in a medical environment. The applications use the capability of optical coherence tomography to achieve real-time, high-resolution, non-contact, and non-destructive interferometric investigations with micrometer resolutions and millimeter penetration depth inside the sample. In this study, testing the quality of the material of one of the most used types of dental prosthesis, metalo-ceramic is thus demonstrated. PMID:25107512

  12. 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.

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

    OpenAIRE

    Baumann, Bernhard; Baumann, Stefan O.; Konegger, Thomas; Pircher, Michael; Götzinger, 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.

  14. Size of the optic nerve in computed tomography

    International Nuclear Information System (INIS)

    Recently, the measurement of optic nerve diameter from CT images has become of great interest. For measuring the optic nerve diameter, the method of Neuro-Ocular index is advocated by Magadure, 1978. But it is very difficult to support this method, because no relationship exists between the ocular diameter and the optic nerve diameter. In order to measure the optic nerve diameter directly by CT image, we examined several Window Level and Window Width settings and print out tables. Results are as follows, 1) Width 400 and all Level settings, all optic nerves appear thick. 2) Width 100, 75, 50 and Level 0 settings show optic nerves thin. 3) Optic nerve looks thick by Width of 100, 75, 50 and Level of -50 settings. 4) By the Level set of CT value of optic nerve in each case and Width set 75 or 50, optic images show nearly the correct diameter. 5) The midpoint of CT value of optic nerve obtained from print out tables are 8 to -22 and the the average is -10. (author)

  15. 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; 3

    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 ...

  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. 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.

  18. 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

  19. Complex conjugate artifact-free adaptive optics optical coherence tomography of in vivo human optic nerve head

    Science.gov (United States)

    Kim, Dae Yu; Werner, John S.; Zawadzki, Robert J.

    2012-12-01

    We acquired in vivo images of the human optic nerve head (ONH) using an adaptive optics-optical coherence tomography (AO-OCT) system. In order to improve imaging of the lamina cribrosa in the ONH with high lateral resolution and sensitivity, we implemented a complex conjugate artifact-free Fourier domain OCT (Fd-OCT) acquisition scheme with a reference arm-based phase shifting method. This allowed positioning of the lamina cribrosa structures near the zero path length difference where AO-OCT imaging achieves highest sensitivity. Implementation of our complex conjugate artifact removal (CCR) method required constant phase shifts between consecutive axial scans (A-scans), generated by continuous beam path-length changes from offsetting the pivot point of the scanning mirror placed in the reference arm. Fourier transform along the transverse axis and a filtering algorithm allowed reconstruction of CCR AO-OCT images. The suppression ratio of the mirror artifact was approximately 22 dB (at 18,000 A-scans per second acquisition speed) with a paperboard test target and an optimum phase-shift value. Finally, we reconstructed the three-dimensional structure of human ONH with enhanced depth range and sensitivity using CCR AO-OCT.

  20. 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.

  1. 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

  2. Improving Key Rate of Optical Fiber Quantum Key Distribution System Based on Channel Tomography

    Science.gov (United States)

    Zhu, Chang-Hua; Quan, Dong-Xiao; Zhang, Fang; Pei, Chang-Xing

    2013-02-01

    We investigate the key rate of polarization-coded optical fiber-based quantum key distribution system (QKD) with BB84 protocol by channel tomography. The quantum bit error rate (QBER) of the QKD system under depolarizing channel is obtained by analyzing output density operators, transmission rate of channel, transmission rate of the receiver and dark count of single photon detector. According to the estimated QBER an LDPC chosen adaptively is applied to information reconciliation and the practical final key rate is discussed. Analysis results show that compared with cascade scheme and no channel knowledge the key rate can be improved by the proposed reconciliation scheme with channel tomography.

  3. The diagnostic study of optical tomography for high-temperature flow fields in the open system

    Science.gov (United States)

    Chen, Yun-yun; Huang, Xiao-gu; Wen, Yan; Guo, Zhen-yan; Song, Yang

    2015-06-01

    In this paper, the application of moiré and emission tomography in diagnosing the high-temperature and illuminant flow field in the open system is studied, and two flames with different spatial size are chosen as typical objects. First of all, the moiré fringes and the corresponding measured two flames are obtained by integrating moiré and emission tomography. After that, the distribution and the brightness of the moiré fringes are compared for the two flame flow fields, as well as the distributions of the refractive index and the components. Then, the temperature distributions of the two flames are compared and analyzed. The results show that, when moiré and emission tomography are applied in diagnosing the high-temperature and illuminant flow field in the open system, the size, the structure and the species components of the measured flow fields have important effect on the final temperature results. Consequently, the specific problem should be specifically analyzed for the optical diagnosis of flow fields.

  4. Quantum Process Tomography of an Optically-Controlled Kerr Non-linearity

    CERN Document Server

    Kupchak, Connor; Jordaan, Bertus; Figueroa, Eden

    2015-01-01

    Any optical quantum information processing machine would be comprised of fully-characterized constituent devices for both single state manipulations and tasks involving the interaction between multiple quantum optical states. Ideally for the latter, would be an apparatus capable of deterministic optical phase shifts that operate on input quantum states with the action mediated solely by auxiliary signal fields. Here we present the complete experimental characterization of a system designed for optically controlled phase shifts acting on single-photon level probe coherent states. Our setup is based on a warm vapor of rubidium atoms under the conditions of electromagnetically induced transparency with its dispersion properties modified through the use of an optically triggered N-type Kerr non-linearity. We fully characterize the performance of our device by sending in a set of input probe states and measuring the corresponding output via balanced homodyne tomography and subsequently performing the technique of ...

  5. 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.

  6. Finite elements parameterization of optical tomography with the radiative transfer equation in frequency domain

    International Nuclear Information System (INIS)

    Optical tomography is a technique of probing semi-transparent media with the help of light sources. In this method, the spatial distribution of the optical properties inside the probed medium is reconstructed by minimizing a cost function based on the errors between the measurements and the predictions of a numerical model of light transport (also called forward/direct model) within the medium at the detectors locations. Optical tomography with finite elements methods involves generally continuous formulations where the optical properties are constant per mesh elements. This study proposes a numerical analysis in the parameterization of the finite elements space of the optical properties in order to improve the accuracy and the contrast of the reconstruction. Numerical tests with noised data using the same algorithm show that continuous finite elements spaces give better results than discontinuous ones by allowing a better transfer of the information between the whole computational nodes of the inversion. It is seen that the results are more accurate when the number of degrees of freedom of the finite element space of the optical properties (number of unknowns) is lowered. This shows that reducing the number of unknowns decreases the ill-posed nature of the inverse problem, thus it is a promising way of regularizing the inversion.

  7. Optical Effects at projection measurements for Terahertz tomography

    Science.gov (United States)

    Brahm, A.; Wilms, A.; Tymoshchuk, M.; Grossmann, C.; Notni, G.; Tünnermann, A.

    2014-10-01

    Optical effects like refraction, diffraction and edge effects have an influence on Terahertz measurements. They can result in image artifacts which makes it difficult to detect and resolve material defects inside the samples. We used a geometrical optical ray tracing approach to analyze the optical effects at Terahertz projection measurements which can be used to perform 2D or 3D THz images. We measured rectangular and cylindrical samples made of PEEK (Polyetheretherketon), POM (Polyoxymethylen), and PMMA (Polymethylmethacrylat) and compared the results to simulations that are realized with the software ZEMAX. We were able to simulate the measured Fresnel refraction and transmission behavior for rectangular cuboids with a length of 25 mm and cylinders with diameter of 25 mm. We showed the influence of diffraction and edge effects at samples with different sizes made of PMMA. Thus, the optical effect of refraction was significant and observable for cylinders with diameters greater than 1.5 mm and holes with diameter greater than 2.5 mm.

  8. Optical coherence tomography monitoring of angioplasty balloon inflation in a deployment tester

    Science.gov (United States)

    Azarnoush, Hamed; Vergnole, Sébastien; Bourezak, Rafik; Boulet, Benoit; Lamouche, Guy

    2010-08-01

    We present an innovative integration of an intravascular optical coherence tomography probe into a computerized balloon deployment system to monitor the balloon inflation process. The high-resolution intraluminal imaging of the balloon provides a detailed assessment of the balloon quality and, consequently, a technique to improve the balloon manufacturing process. A custom-built swept-source optical coherence tomography system is used for real-time imaging. A semicompliant balloon with a nominal diameter of 4 mm is fabricated for the experiments. Imaging results correspond to balloon deployment in air and inside an artery phantom. A characterization of the balloon diameter, wall thickness, compliance, and elastic modulus is provided, based on image segmentation. Using the images obtained from the probe pullback, a three-dimensional visualization of the inflated balloon is presented.

  9. Improved phase-resolved optical Doppler tomography using the Kasai velocity estimator and histogram segmentation

    Science.gov (United States)

    Yang, Victor X. D.; Gordon, Maggie L.; Mok, Alvin; Zhao, Yonghua; Chen, Zhongping; Cobbold, Richard S. C.; Wilson, Brian C.; Alex Vitkin, I.

    2002-07-01

    Significant improvements are reported in the measurable velocity range and tissue motion artefact rejection of a phase-resolved optical coherence tomography and optical Doppler tomography system. Phase information derived from an in-phase and quadrature demodulator is used to estimate the mean blood flow velocity by the Kasai autocorrelation algorithm. A histogram-based velocity segmentation algorithm is used to determine block tissue movement and remove tissue motion artefacts that can be faster or slower in velocity than that of the microcirculation. The minimum detectable Doppler frequency is about 100 Hz, corresponding to a flow velocity resolution of 30 ?m/s with an axial-line scanning frequency of 8.05 kHz and a mean phase change measured over eight sequential scans; the maximum detectable Doppler frequency is ±4 kHz (for bi-directional flow) before phase wrap-around.

  10. 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...

  11. Mid-ventricular Tako-Tsubo cardiomyopathy with structurally normal coronary arteries confirmed by optical coherence tomography.

    Science.gov (United States)

    Alfonso, Fernando; Cárdenas, Alberto; Ibáñez, Borja

    2013-12-01

    Tako-Tsubo cardiomyopathy is an entity of unknown etiology characterized by transient apical dyskinesia in patients with angiographically normal coronary arteries. However, atypical forms of Tako-Tsubo cardiomyopathy may also occur, affecting other myocardial segments. Optical coherence tomography has a unique resolution and may detect angiographically silent atherosclerotic coronary artery disease. In this report, we describe optical coherence tomography findings in a patient with atypical Tako-Tsubo cardiomyopathy presenting as transient mid-ventricular ballooning. PMID:24296394

  12. 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).

  13. 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.

  14. Combining Optical Coherence Tomography with Fluorescence Molecular Imaging: Towards Simultaneous Morphology and Molecular Imaging

    OpenAIRE

    Yuan, Shuai; Roney, Celeste A.; Wierwille, Jerry; Chen, Chao-wei; Xu, Biying; Jiang, James; Ma, Hongzhou; Cable, Alex; Summers, Ronald M.; Chen, Yu

    2010-01-01

    Optical coherence tomography (OCT) provides high-resolution, cross-sectional imaging of tissue microstructure in situ and in real-time, while fluorescence molecular imaging (FMI) enables the visualization of basic molecular processes. There are great interests in combining these two modalities so that the tissue's structural and molecular information can be obtained simultaneously. This could greatly benefit biomedical applications such as detecting early diseases and monitoring therapeutic i...

  15. Automated assessment of the remineralization of artificial enamel lesions with polarization-sensitive optical coherence tomography

    OpenAIRE

    Lee, Robert C; Kang, Hobin; Darling, Cynthia L; Fried, Daniel

    2014-01-01

    Accurate measurement of the highly mineralized transparent surface layer that forms on caries lesions is important for diagnosis of the lesion activity because chemical intervention can slow or reverse the caries process via remineralization. Previous in-vitro and in-vivo studies have demonstrated that polarization-sensitive optical coherence tomography (PS-OCT) can nondestructively image the subsurface lesion structure and the highly mineralized transparent surface zone of caries lesions. Th...

  16. Visualization of peripheral pulmonary artery red thrombi utilizing optical coherence tomography

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Cheng; Wang, Wei; Zhong, Nan Shan; Zeng, Guang Qiao; Zhang, Nuo Fu [The First Affiliated Hospital of Guangzhou Medical College, Guangzhou (China)

    2013-10-15

    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.

  17. A Fast Reconstruction Algorithm for Fluorescence Optical Diffusion Tomography Based on Preiteration

    OpenAIRE

    Xiaolei Song; Xiaoyun Xiong; Jing Bai

    2007-01-01

    Fluorescence optical diffusion tomography in the near-infrared (NIR) bandwidth is considered to be one of the most promising ways for noninvasive molecular-based imaging. Many reconstructive approaches to it utilize iterative methods for data inversion. However, they are time-consuming and they are far from meeting the real-time imaging demands. In this work, a fast preiteration algorithm based on the generalized inverse matrix is proposed. This method needs only one step of matrix-vector mul...

  18. Maximum-likelihood estimation in Optical Coherence Tomography in the context of the tear film dynamics

    OpenAIRE

    Huang, Jinxin; Clarkson, Eric; Kupinski, Matthew; Lee, Kye-sung; Maki, Kara L.; Ross, David S.; Aquavella, James V.; Rolland, Jannick P.

    2013-01-01

    Understanding tear film dynamics is a prerequisite for advancing the management of Dry Eye Disease (DED). In this paper, we discuss the use of optical coherence tomography (OCT) and statistical decision theory to analyze the tear film dynamics of a digital phantom. We implement a maximum-likelihood (ML) estimator to interpret OCT data based on mathematical models of Fourier-Domain OCT and the tear film. With the methodology of task-based assessment, we quantify the tradeoffs among key imaging...

  19. Magnetic and Contrast Properties of Labeled Platelets for Magnetomotive Optical Coherence Tomography

    OpenAIRE

    Oldenburg, Amy L.; Gallippi, Caterina M.; Tsui, Frank; Nichols, Timothy C.; Beicker, Kellie N.; Chhetri, Raghav K.; Spivak, Dmitry; Richardson, Aaron; Fischer, Thomas H.

    2010-01-01

    This article introduces a new functional imaging paradigm that uses optical coherence tomography (OCT) to detect rehydrated, lyophilized platelets (RL platelets) that are in the preclinical trial stage and contain superparamagnetic iron oxides (SPIOs) approved by the U.S. Food and Drug Administration. Platelets are highly functional blood cells that detect and adhere to sites of vascular endothelial damage by forming primary hemostatic plugs. By applying magnetic gradient forces, induced nano...

  20. Principal-component-analysis-based estimation of blood flow velocities using optical coherence tomography intensity signals

    OpenAIRE

    Mohan, Nishant; Vakoc, Benjamin

    2011-01-01

    The intensity signal in optical coherence tomography contains information about the translational velocity of scatterers, and can be used to quantify blood flow. We apply principal component analysis to efficiently extract this information. We also study use of nonuniform temporal sampling of the intensity signal to increase the range of quantifiable flow velocities. We demonstrate this technique in simulation, phantom and in vivo blood flow measurements, and highlight its potential to enable...

  1. 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...

  2. Fundus autofluorescence and optical coherence tomography findings in glutathione synthetase deficiency.

    Science.gov (United States)

    ?ekero?lu, Hande Taylan; Hismi, Burcu; Kadayifcilar, Sibel; Coskun, Turgay

    2015-02-01

    We report the autofluorescence pattern and optical coherence tomography (OCT) characteristics in a 6-year-old boy with glutathione synthetase deficiency. The patient underwent complete ophthalmological examination, including full-field electroretinography, visual evoked potentials, fundus autofluorescence, and OCT imaging. Electrophysiological studies showed time-delay and subnormal responses. Fundus autofluorescence imaging revealed increased parafoveal autofluorescence compared to normal, and OCT showed alteration of photoreceptor and retinal pigment epithelium layers in the parafoveal region. PMID:25727596

  3. Reproducibility of Scleral Spur Identification and Angle Measurements Using Fourier Domain Anterior Segment Optical Coherence Tomography

    OpenAIRE

    Mankiewicz, Kimberly A.; Robert M Feldman; Shan C. Lin; Alice Z. Chuang; Nagi, Kundandeep S.; Nicholas P. Bell; Sunita Radhakrishnan; Cumba, Ricardo J.

    2012-01-01

    Purpose. To evaluate intraobserver and interobserver agreement in locating the scleral spur landmark (SSL) and anterior chamber angle measurements obtained using Fourier Domain Anterior Segment Optical Coherence Tomography (ASOCT) images. Methods. Two independent, masked observers (SR and AZC) identified SSLs on ASOCT images from 31 eyes with open and nonopen angles. A third independent reader, NPB, adjudicated SSL placement if identifications differed by more than 80??m. Nine months later, S...

  4. Autocorrelation optical coherence tomography for mapping transverse particle-flow velocity

    OpenAIRE

    Wang, Yi; Wang, Ruikang

    2010-01-01

    We present an autocorrelation method to quantitatively map transverse particle-flow velocity with a Fourier domain optical coherence tomography system. This method is derived from the intensity fluctuation of the backscattered light modulated by flowing particles. When passing through the probe beam, moving particles encode a transit time into the backscattered light. The slope of the normalized autocorrelation function of the backscattered light is proportional to the transverse velocity. Th...

  5. Fluorescence diffuse optical tomography: Time-resolved versus continuous-wave in the reflectance configuration

    OpenAIRE

    Ducros, Nicolas; D Andrea, Cosimo; Bassi, Andrea; Peyrin, Franc?oise

    2011-01-01

    Context and objectives In the context of fluorescence diffuse optical tomography, the time-resolved approach was shown to improve the reconstruction quality compared to the continuous-wave approach when adopting the transmittance configuration. However, the improvement seriously decreases in the presence of noise. The scope of this paper is to investigate the additional value of the time-resolved approach in the reflectance configuration. Material and methods A comparative study between time-...

  6. 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...

  7. Temporal coherence and time–frequency distributions in spectroscopic optical coherence tomography

    OpenAIRE

    Graf, Robert N.; Wax, Adam

    2007-01-01

    Traditional analysis of spectroscopic optical coherence tomography (SOCT) signals is limited by an uncertainty relationship between time (depth) and frequency (wavelength). The use of a bilinear time–frequency distribution for analysis, such as those that compose Cohen’s class of functions, may provide a way to avoid this limitation. Here we present the relationship between traditional SOCT analysis and the relevant Cohen class functions: the Wigner and Choi–Williams distributions. Whil...

  8. Real-time processing for Fourier domain optical coherence tomography using a field programmable gate array

    OpenAIRE

    Ustun, Teoman E.; Iftimia, Nicusor V.; Ferguson, R. Daniel; Hammer, Daniel X.

    2008-01-01

    Real-time display of processed Fourier domain optical coherence tomography (FDOCT) images is important for applications that require instant feedback of image information, for example, systems developed for rapid screening or image-guided surgery. However, the computational requirements for high-speed FDOCT image processing usually exceeds the capabilities of most computers and therefore display rates rarely match acquisition rates for most devices. We have designed and developed an image pro...

  9. Use of Split Bregman denoising for iterative reconstruction in fluorescence diffuse optical tomography

    OpenAIRE

    Chamorro-servent, Judit; Pe?rez-juste Abascal, Juan Felipe; Aguirre, Juan; Arridge, Simon; Correia, Teresa; Ripoll Lorenzo, Jorge; Desco, Manuel; Vaquero, Juan Jose?

    2013-01-01

    Fluorescence diffuse optical tomography (fDOT) is a noninvasive imaging technique that makes it possible to quantify the spatial distribution of fluorescent tracers in small animals. fDOT image reconstruction is commonly performed by means of iterative methods such as the algebraic reconstruction technique (ART). The useful results yielded by more advanced l1-regularized techniques for signal recovery and image reconstruction, together with the recent publication of Split Bregman (SB) procedu...

  10. 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

    2015-04-01

    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.

  11. 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.

  12. Fully automated side branch detection in intravascular optical coherence tomography pullback runs

    OpenAIRE

    Wang, Ancong; Eggermont, Jeroen; Reiber, Johan H C; Dijkstra, Jouke

    2014-01-01

    Side branches in the atherosclerotic lesion region are important as they highly influence the treatment strategy selection and optimization. Moreover, they are reliable landmarks for image registration. By providing high resolution delineation of coronary morphology, intravascular optical coherence tomography (IVOCT) has been increasingly used for side branch analysis. This paper presents a fully automated method to detect side branches in IVOCT images, which relies on precise segmentation of...

  13. Automatic detection of bioresorbable vascular scaffold struts in intravascular optical coherence tomography pullback runs

    OpenAIRE

    Wang, Ancong; Nakatani, Shimpei; Eggermont, Jeroen; Onuma, Yoshi; Garcia-Garcia, Hector M; Serruys, Patrick W.; Reiber, Johan H C; Dijkstra, Jouke

    2014-01-01

    Bioresorbable vascular scaffolds (BVS) have gained significant interest in both the technical and clinical communities as a possible alternative to metallic stents. For accurate BVS analysis, intravascular optical coherence tomography (IVOCT) is currently the most suitable imaging technique due to its high resolution and the translucency of polymeric BVS struts for near infrared light. However, given the large number of struts in an IVOCT pullback run, quantitative analysis is only feasible w...

  14. Automatic segmentation of the choroid in enhanced depth imaging optical coherence tomography images

    OpenAIRE

    Tian, Jing; Marziliano, Pina; Baskaran, Mani; Tun, Tin Aung; Aung, Tin

    2013-01-01

    Enhanced Depth Imaging (EDI) optical coherence tomography (OCT) provides high-definition cross-sectional images of the choroid in vivo, and hence is used in many clinical studies. However, the quantification of the choroid depends on the manual labelings of two boundaries, Bruch’s membrane and the choroidal-scleral interface. This labeling process is tedious and subjective of inter-observer differences, hence, automatic segmentation of the choroid layer is highly desirable. In this paper, w...

  15. 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.

  16. Alignment of 3-D Optical Coherence Tomography Scans to Correct Eye Movement Using a Particle Filtering

    OpenAIRE

    Xu, Juan; Ishikawa, Hiroshi; Wollstein, Gadi; Kagemann, Larry; Schuman, Joel S.

    2012-01-01

    Eye movement artifacts occurring during 3-D optical coherence tomography (OCT) scanning is a well-recognized problem that may adversely affect image analysis and interpretation. A particle filtering algorithm is presented in this paper to correct motion in a 3-D dataset by considering eye movement as a target tracking problem in a dynamic system. The proposed particle filtering algorithm is an independent 3-D alignment approach, which does not rely on any reference image. 3-D OCT data is cons...

  17. New Insight into Rheology and Flow Properties of Complex Fluids with Doppler Optical Coherence Tomography

    OpenAIRE

    JuhaSalmela

    2014-01-01

    Flow properties of complex fluids such as colloidal suspensions, polymer solutions, fiber suspensions and blood have a vital function in many technological applications and biological systems. Yet, the basic knowledge on their properties is inadequate for many practical purposes. One important reason for this has been the lack of effective experimental methods that would allow detailed study of the flow behavior of especially opaque multi-phase fluids. Optical Coherence Tomography (OCT) is an...

  18. Macular thickness measurements in healthy Norwegian volunteers: an optical coherence tomography study

    OpenAIRE

    Sand Trond; Wexler Alexandra; Elsås Tor B

    2010-01-01

    Abstract Background Ethnic, intersubject, interoperator and intermachine differences in measured macular thickness seem to exist. Our purpose was to collect normative macular thickness data in Norwegians and to evaluate the association between macular thickness and age, gender, parity, and contraception status. Methods Retinal thickness was measured by Stratus Optical Coherence Tomography in healthy subjects. Mean macular thickness (MMT) was analyzed by repeated measures ANOVA with three depe...

  19. Influence of dental resin material composition on cross-polarization-optical coherence tomography imaging

    OpenAIRE

    Lammeier, Carmen; Li, Yuping; Lunos, Scott; Fok, Alex; Rudney, Joel; Jones, Robert S.

    2012-01-01

    The purpose of this study was to investigate cross-polarization-optical coherence tomography (CP-OCT) signal attenuation through different resin material compositions. Four distinct composite systems were used: Filtek supreme ultra (FSU) (3M ESPE), IPS empress direct (EMD) (Ivoclar Vivadent), estelite sigma quick (SQK) (Tokuyama Dental), and Z100 (3M ESPE). Cross-sectional images of different composite-demineralized phantoms (n=108) were collected using a 1310-nm intraoral cross-polarization ...

  20. Brain specificity of diffuse optical imaging: improvements from superficial signal regression and tomography

    OpenAIRE

    AndrewJ Berger; JosephPCulver

    2010-01-01

    Functional near infrared spectroscopy (fNIRS) is a portable monitor of cerebral hemodynamics with wide clinical potential. However, in fNIRS, the vascular signal from the brain is often obscured by vascular signals present in the scalp and skull. In this paper, we evaluate two methods for improving in vivo data from adult human subjects through the use of high-density diffuse optical tomography (DOT). First, we test whether we can extend superficial regression methods (which utilize the multi...

  1. Exact and Efficient Signal Reconstruction in Frequency-Domain Optical-Coherence Tomography

    OpenAIRE

    Seelamantula, C. S.; Villiger, M. L.; Leitgeb, R. A.; Unser, M.

    2008-01-01

    We address the problem of tomogram reconstruction in frequency-domain optical-coherence tomography. We propose a new technique for suppressing the autocorrelation artifacts that are commonly encountered with the conventional Fourier-transform-based approach. The technique is based on the assumptions that the scattering function is causal and that the intensity of the light reflected from the object is smaller than that of the reference. The technique is noniterative, nonlinear, and yields an ...

  2. Optimization of an angled fiber probe for common-path optical coherence tomography

    OpenAIRE

    Liu, Xuan; Kang, Jin U.

    2013-01-01

    We studied optimization of common-path optical coherence tomography (CP OCT) sensitivity through angled fiber probe. The magnitude of reference power derived from the tip of the fiber was optimized through careful selection of the polishing angle. We experimentally measured the signal-to-noise ratio at different polishing angles to validate the effectiveness of this technique. We also obtained OCT images with the reference optimized CP OCT with more than 10 dB improvement in SNR..

  3. 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...

  4. Use of an oxygen-carrying blood substitute to improve intravascular optical coherence tomography imaging

    OpenAIRE

    Hoang, Khiet C.; Edris, Ahmad; Su, Jianping; Mukai, David S.; Mahon, Sari; Petrov, Artiom D.; Kern, Morton; Ashan, Chowdhury; Chen, Zhongping; Tromberg, Bruce J.; Narula, Jagat; Brenner, Matthew

    2009-01-01

    Optical coherence tomography (OCT) is a catheter-based imaging technology with powerful resolution capable of identifying vulnerable plaques and guiding coronary intervention. However, a significant limitation of intravascular OCT imaging is its attenuation by blood. We propose that the use of an oxygen-carrying blood substitute could potentially optimize OCT image quality. Surgical isolation of the descending thoracic aorta of six rabbits is performed, followed by intravascular OCT imaging o...

  5. 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...

  6. Validation of a New Animal Model of Vulnerable Plaques by Intravascular Optical Coherence Tomography In Vivo

    OpenAIRE

    Yan Fang; Sining Hu; Jingbo Hou; Lingbo Meng; Shaosong Zhang; Bo Yu

    2012-01-01

    We aimed to establish a rabbit model of vulnerable plaques (VPs) with the morphology and component characteristics of human VPs and to evaluate the microstructural features of VPs in vivo using intravascular optical coherence tomography (OCT). Twelve rabbits underwent endothelial denudation of the carotid artery and consumed a 1% high-cholesterol diet (HCD). They were equally divided into two groups: group A (modified needle injury) and group B (balloon injury). OCT was undertaken thrice befo...

  7. Miniaturized magnetic-driven scanning probe for endoscopic optical coherence tomography

    OpenAIRE

    Pang, Ziwei; Wu, Jigang

    2015-01-01

    We designed and implemented a magnetic-driven scanning (MDS) probe for endoscopic optical coherence tomography (OCT). The probe uses an externally-driven tiny magnet in the distal end to achieve unobstructed 360-degree circumferential scanning at the side of the probe. The design simplifies the scanning part inside the probe and thus allows for easy miniaturization and cost reduction. We made a prototype probe with an outer diameter of 1.4 mm and demonstrated its capability by acquiring OCT i...

  8. 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

  9. [Optical coherence tomography of coronary arteries--a novel intravascular imaging modality].

    Science.gov (United States)

    Mrevlje, B; Legutko, J; J?ka?a, J; No?, M; Dudek, D; Birkemeyer, R; Aboukoura, M; Nienaber, C

    2014-09-01

    Optical coherence tomography (OCT) is the latest intravascular imaging modality for the investigation of coronary arteries. It can be used in patients with stable coronary artery disease as well as in patients with acute coronary syndrome. Its almost microscope-like resolution of 10-20 ?m (10-times greater than intravascular ultrasound) gives us the most detailed insight into the coronary artery wall in vivo so far.Optical coherence tomography can be used for accurate qualitative and quantitative assessment of stenoses in stable coronary artery disease and accurate guidance of percutaneous coronary interventions as well as accurate postprocedural control. In patients with acute coronary syndrome it can be used for the detection of culprit of the culprit lesion (vulnerable plaque) which allows the operator to cover not only angiographically tightest stenosis (angiographic culprit lesion, caused in most cases by thrombus only) but most importantly the vulnerable plaque, which led to the acute event, as well. Furthermore, optical coherence tomography allows accurate assessment of thrombotic burden, stent apposition/malapposition, edge dissections and tissue prolaps or thrombus protrusions throught stent struts, etc. PMID:25225864

  10. [Optical coherence tomography. Bases and applications of a new intravascular imaging technique].

    Science.gov (United States)

    Macías, Enrico; Medina, Miguel Ángel; Gonzalo, Nieves; del Angel, Juan; Escaned, Javier

    2013-01-01

    Coronary angiography is the reference technique for the diagnosis of coronary disease. However, the majority of acute coronary syndromes involve angiographically non-significant lesions. It is also the technique of choice for guiding the implantation of endovascular prostheses and their later monitoring. Optical coherence tomography is an interferometric imaging technique that penetrates tissue approximately 2-3mm and provides axial and lateral resolution. It is able to distinguish different tissue types, such as fibrous, lipid-rich, necrotic, or calcified tissue. Optical coherence tomography is able to recognize a variety of features of atherosclerotic plaques that have been associated with rapid lesion progression and clinical events, such as thin cap fibroatheroma, fibrous cap thickness, dense macrophage infiltration, and thrombus formation. Currently, there is growing interest in the value of optical coherence tomography in the area of coronary intervention, where the technique offers significant advantages over more widespread intravascular diagnostic techniques such as intravascular ultrasound. Its higher resolution permits to recognize periprocedural complications, such as microdissection of the coronary artery, stent malapposition, and neointimal hyperplasia, making this tool one of the most promising techniques in the intravascular diagnosis. PMID:23648202

  11. Stellate figure in the macula: visualization in the Henle fiber layer on optical coherence tomography

    Directory of Open Access Journals (Sweden)

    Makino S

    2014-01-01

    Full Text Available Shinji Makino, Meri Watanabe, Hironobu TampoDepartment of Ophthalmology, Jichi Medical University, Shimotsuke, Tochigi, JapanAbstract: A 21-year-old woman complaining of a sudden visual disturbance in her left eye was referred to our hospital. The best-corrected visual acuity (BCVA in the left eye was 0.3. Fundus examination revealed tortuous retinal veins, soft exudates, and retinal edema. Optical coherence tomography showed that the macular thickness was increased to 685 µm. We diagnosed the condition as a central retinal vein occlusion. Systemic administration of an antiplatelet agent was initiated. The BCVA improved to 0.6, the retinal edema dramatically resolved, and the macular thickness was reduced to 318 µm 1 week later. Furthermore, the reduced retinal edema had transformed to many spokes in a wheel of exudates, a so-called “stellate figure”s, in the macula. On optical coherence tomography, hyper-reflective substances were detected in the Henle fiber layer. One month later, the BCVA improved to 1.0. Changes in microstructural findings and visual acuity were analogous during the recovery of macular edema in our patient.Keywords: stellate figure in the macula, Henle fiber layer, central retinal vein occlusion, macular edema, optical coherence tomography

  12. Assessment of wave propagation on surfaces of crystalline lens with phase sensitive optical coherence tomography

    International Nuclear Information System (INIS)

    We propose a real-time technique based on phase-sensitive swept source optical coherence tomography (PhS-SSOCT) modality for noninvasive quantification of very small optical path length changes produced on the surface of a mouse crystalline lens. Propagation of submicron mechanical waves on the surface of the lens was induced by periodic mechanical stimulation. Obtained results demonstrate that the described method is capable of detecting minute damped vibrations with amplitudes as small as 30 nanometers on the lens surface and hence, PhS-SSOCT could be potentially used to assess biomechanical properties of a crystalline lens with high accuracy and sensitivity

  13. Functional Optical Coherence Tomography Enables In Vivo Physiological Assessment of Retinal Rod and Cone Photoreceptors

    Science.gov (United States)

    Zhang, Qiuxiang; Lu, Rongwen; Wang, Benquan; Messinger, Jeffrey D.; Curcio, Christine A.; Yao, Xincheng

    2015-04-01

    Transient intrinsic optical signal (IOS) changes have been observed in retinal photoreceptors, suggesting a unique biomarker for eye disease detection. However, clinical deployment of IOS imaging is challenging due to unclear IOS sources and limited signal-to-noise ratios (SNRs). Here, by developing high spatiotemporal resolution optical coherence tomography (OCT) and applying an adaptive algorithm for IOS processing, we were able to record robust IOSs from single-pass measurements. Transient IOSs, which might reflect an early stage of light phototransduction, are consistently observed in the photoreceptor outer segment almost immediately (macular degeneration (AMD) and other eye diseases that can cause photoreceptor damage.

  14. 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.

  15. 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)

  16. Two- and three-dimensional optical tomography of finger joints for diagnostics of rheumatoid arthritis

    Science.gov (United States)

    Klose, Alexander D.; Hielscher, Andreas H.; Hanson, Kenneth M.; Beuthan, Juergen

    1998-12-01

    Rheumatoid arthritis (RA) is one of the most common diseases of human joints. This progressive disease is characterized by an inflammation process that originates in the inner membrane (synovalis) of the capsule and spreads to other parts of the joint. In early stages the synovalis thickness and the permeability of this membrane changes. This leads to changes in the optical parameters of the synovalis and the synovial fluid (synovia), which occupies the space between the bones. The synovia changes from a clear yellowish fluid to a turbid grayish substance. In this work we present 2 and 3-dimensional reconstruction schemes for optical tomography of the finger joints. Our reconstruction algorithm is based on the diffusion approximation and employs adjoint differentiation techniques for the gradient calculation of the objective function with respect to the spatial distribution of optical properties. In this way, the spatial distribution of optical properties within the joints is reconstructed with high efficiency and precision. Volume information concerning the synovial space and the capsula are provided. Furthermore, it is shown that small changes of the scattering coefficients can be monitored. Therefore, optical tomography has the potential of becoming a useful tool for the early diagnosis and monitoring of disease progression in RA.

  17. 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 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

  18. Polarization maintaining fiber based ultra-high resolution spectral domain polarization sensitive optical coherence tomography.

    Science.gov (United States)

    Götzinger, Erich; Baumann, Bernhard; Pircher, Michael; Hitzenberger, Christoph K

    2009-12-01

    We present a new ultra high resolution spectral domain polarization sensitive optical coherence tomography (PS-OCT) system based on polarization maintaining (PM) fibers. The method transfers the principles of our previous bulk optic PS-OCT systems to a fiberized setup. The phase shift between the orthogonal polarization states travelling in the two orthogonal modes of the PM fiber is compensated by software in post processing. Thereby, the main advantage of our bulk optics setups, i.e. the use of only a single input polarization state to simultaneously acquire reflectivity, retardation, optic axis orientation, and Stokes vector, is maintained. The use of a broadband light source of 110 nm bandwidth provides improved depth resolution and smaller speckle size. The latter is important for improved resolution of depolarization imaging. We demonstrate our instrument for high-resolution PS-OCT imaging of the healthy human retina. PMID:20052196

  19. Simultaneous determination of the tissue light scattering coefficient and Brownian diffusion coefficient using optical coherence tomography

    International Nuclear Information System (INIS)

    Diseased tissue has different optical properties and dynamic behaviors from normal tissue, and this can be exploited for diagnostics and therapeutics. We present a model for simultaneously estimating the optical scattering coefficient and Brownian diffusion coefficient of superficial biological tissue. This theoretical model predicts that the U-quadratic distribution approximates the Lorentzian power spectrum due to the Brownian motion, when the frequency width of integration is much less than the power spectrum linewidth. Furthermore, it shows that the logarithmic intensity of all calculated wavelet frequencies is linearly dependent on the scattering coefficient and the standard deviation of the Doppler frequency shift is linearly dependent on the Brownian diffusion coefficient in the region of the single scattering length. An optical coherence tomography system was used to measure the optical scattering coefficient and the Brownian diffusion coefficient of phantoms. The results of our theoretical model are consistent with the experimental results. Thus, the method has the potential for diagnosis of diseases. (paper)

  20. Tomography

    International Nuclear Information System (INIS)

    Tomography images of a body are constructed by placing a plurality of surface electrodes at spaced intervals on the body, causing currents to flow in the body (e.g. by applying a potential between each pair of electrodes in turn, or by induction), and measuring the potential between pairs of electrodes, calculating the potential expected in each case on the assumption that the body consists of a medium of uniform impedance, plotting the isopotentials corresponding to the calculated results to create a uniform image of the body, obtaining the ratio between the measured potential and the calculated potential in each case, and modifying the image in accordance with the respective ratios by increasing the assumed impedance along an isopotential in proportion to a ratio greater than unity or decreasing the assumed impedance in proportion to a ratio less than unity. The modified impedances along the isopotentials for each pair of electrodes are superimposed. The calculations are carried out using a computer and the plotting is carried out by a visual display unit and/or a print-out unit. (author)

  1. Numerical and experimental studies of x-ray luminescence optical tomography for small animal imaging

    Science.gov (United States)

    Li, Changqing; Martínez Dávalos, Arnulfo; Cherry, Simon R.

    2013-03-01

    X-ray luminescence optical tomography (XLOT) is an emerging hybrid imaging modality in which x-ray excitable particles (phosphor particles) emit optical photons when stimulated with a collimated x-ray beam. XLOT combines the high sensitivity of optical imaging with the high spatial resolution of x-ray imaging. For XLOT reconstruction, we compared two reconstruction algorithms, conventional filtered backprojection (FBP) and a new algorithm, x-ray luminescence optical tomography with excitation priors (XLOT-EP), in which photon propagation is modeled with the diffusion equation and the x-ray beam positions are used as reconstruction priors. Numerical simulations based on dose calculations are used to validate the proposed XLOT imaging system and the reconstruction algorithms. Simulation results show that XLOT can better detect inclusions of particles than x-ray computed tomography (CT) alone. Nanoparticle concentrations reconstructed with XLOT-EP are much less dependent on target depths than those obtained with FBP. Measurements at just two orthogonal projections are sufficient for the XLOT-EP to reconstruct an XLOT image for simple source distributions. The heterogeneity of x-ray dose distribution is included in the XLOT-EP reconstruction and improves the reconstruction accuracy, suggesting that there is a need to calculate the x-ray dose distribution for experimental XLOT imaging. We have built a prototype XLOT imaging system, in which a collimated x-ray bean is used to scan the samples and an electron multiplying charge couple device (EMCCD) is used to collect the optical photons emitted by the x-ray excitable particles. Phantom experiments have been performed to validate the XLOT system and the proposed reconstruction algorithms.

  2. Optical tomography reconstruction algorithm with the finite element method: An optimal approach with regularization tools

    International Nuclear Information System (INIS)

    Highlights: •New strategies to improve the accuracy of the reconstruction through mesh and finite element parameterization. •Use of gradient filtering through an alternative inner product within the adjoint method. •An integral form of the cost function is used to make the reconstruction compatible with all finite element formulations, continuous and discontinuous. •Gradient-based algorithm with the adjoint method is used for the reconstruction. -- Abstract: Optical tomography is mathematically treated as a non-linear inverse problem where the optical properties of the probed medium are recovered through the minimization of the errors between the experimental measurements and their predictions with a numerical model at the locations of the detectors. According to the ill-posed behavior of the inverse problem, some regularization tools must be performed and the Tikhonov penalization type is the most commonly used in optical tomography applications. This paper introduces an optimized approach for optical tomography reconstruction with the finite element method. An integral form of the cost function is used to take into account the surfaces of the detectors and make the reconstruction compatible with all finite element formulations, continuous and discontinuous. Through a gradient-based algorithm where the adjoint method is used to compute the gradient of the cost function, an alternative inner product is employed for preconditioning the reconstruction algorithm. Moreover, appropriate re-parameterization of the optical properties is performed. These regularization strategies are compared with the classical Tikhonov penalization one. It is shown that both the re-parameterization and the use of the Sobolev cost function gradient are efficient for solving such an ill-posed inverse problem

  3. Application of adaptive optics: optical coherence tomography for in vivo imaging of microscopic structures in the retina and optic nerve head

    Science.gov (United States)

    Zawadzki, Robert J.; Zhang, Yan, II; Jones, Steven M.; Choi, Stacey S.; Cense, Barry; Chen, Diana; Fuller, Alfred R.; Miller, Donald T.; Olivier, Scot S.; Werner, John S.

    2007-02-01

    Two deformable mirrors (2DM) were used in an adaptive optics - optical coherence tomography (AO-OCT) system to image in vivo microscopic retinal structures of healthy and diseased retinas. As a result, multiple morphological structures not previously seen in vivo have been visualized. Among those presented are three-dimensional representations of the fovea and optic nerve head (ONH), revealing cellular structures and micro-vasculature. Drusen in macular degeneration and photoreceptor dystrophies are also presented. Different methods for displaying volumetric AO-OCT data to facilitate visualization of certain morphological details are compared.

  4. Multiple Object Adaptive Optics: Mixed NGS/LGS tomography

    Science.gov (United States)

    Morris, Tim; Gendron, Eric; Basden, Alastair; Martin, Olivier; Osborn, James; Henry, David; Hubert, Zoltan; Sivo, Gaetano; Gratadour, Damien; Chemla, Fanny; Sevin, Arnaud; Cohen, Matthieu; Younger, Eddy; Vidal, Fabrice; Wilson, Richard; Batterley, Tim; Bitenc, Urban; Reeves, Andrew; Bharmal, Nazim; Raynaud, Henri-François; Kulcsar, Caroline; Conan, Jean-Marc; Guzman, Dani; De Cos Juez, Javier; Huet, Jean-Michel; Perret, Denis; Dickson, Colin; Atkinson, David; Baillie, Tom; Longmore, Andy; Todd, Stephen; Talbot, Gordon; Morris, Simon; Myers, Richard; Rousset, Gérard

    2013-12-01

    Open-loop adaptive optics has been successfully demonstrated on-sky by several groups, including the fully tomographic MOAO demonstration made using CANARY. MOAO instrumentation such as RAVEN will deliver the first astronomical science and other planned instruments aim to extend both open-loop AO performance and the number of corrected fields. Many of these planned systems rely on the use of tomographic open-loop LGS wavefront sensing. Here we present results from the combined NGS/LGS tomographic CANARY system and then compare the NGS- and LGS-based tomographic system performance. We identify the major system performance drivers, and highlight some potential routes for further exploitation of open-loop tomographic AO.

  5. Versatile Wideband Balanced Detector for Quantum Optical Homodyne Tomography

    CERN Document Server

    Kumar, Ranjeet; MacRae, Andrew; Cairns, E; Huntington, E H; Lvovsky, A I

    2011-01-01

    We present a comprehensive theory and an easy to follow method for the design and construction of a wideband homodyne detector for time-domain quantum measurements. We show how one can evaluate the performance of a detector in a specific time-domain experiment based on electronic spectral characteristic of that detector. We then present and characterize a high-performance detector constructed using inexpensive, commercially available components such as low-noise high-speed operational amplifiers and high-bandwidth photodiodes. Our detector shows linear behavior up to a level of over 13 dB clearance between shot noise and electronic noise, in the range from DC to 100 MHz. The detector can be used for measuring quantum optical field quadratures both in the continuous-wave and pulsed regimes with pulse repetition rates up to about 250 MHz.

  6. Hyperspectral and multispectral bioluminescence optical tomography for small animal imaging

    International Nuclear Information System (INIS)

    For bioluminescence imaging studies in small animals, it is important to be able to accurately localize the three-dimensional (3D) distribution of the underlying bioluminescent source. The spectrum of light produced by the source that escapes the subject varies with the depth of the emission source because of the wavelength-dependence of the optical properties of tissue. Consequently, multispectral or hyperspectral data acquisition should help in the 3D localization of deep sources. In this paper, we describe a framework for fully 3D bioluminescence tomographic image acquisition and reconstruction that exploits spectral information. We describe regularized tomographic reconstruction techniques that use semi-infinite slab or FEM-based diffusion approximations of photon transport through turbid media. Singular value decomposition analysis was used for data dimensionality reduction and to illustrate the advantage of using hyperspectral rather than achromatic data. Simulation studies in an atlas-mouse geometry indicated that sub-millimeter resolution may be attainable given accurate knowledge of the optical properties of the animal. A fixed arrangement of mirrors and a single CCD camera were used for simultaneous acquisition of multispectral imaging data over most of the surface of the animal. Phantom studies conducted using this system demonstrated our ability to accurately localize deep point-like sources and show that a resolution of 1.5 to 2.2 mm for depths up to 6 mmion of 1.5 to 2.2 mm for depths up to 6 mm can be achieved. We also include an in vivo study of a mouse with a brain tumour expressing firefly luciferase. Co-registration of the reconstructed 3D bioluminescent image with magnetic resonance images indicated good anatomical localization of the tumour

  7. Changes in retinal nerve fiber layer and optic disc algorithms by optical coherence tomography in glaucomatous Arab subjects

    Directory of Open Access Journals (Sweden)

    Zeried FM

    2013-09-01

    Full Text Available Ferial M Zeried, Uchechukwu L Osuagwu Department of Optometry and Vision Sciences College of Applied Medical Sciences, King Saud University, Riyadh, Kingdom of Saudi Arabia Purpose: To assess the difference in retinal nerve fiber layer (RNFL and optic disc algorithms between glaucomatous and normal Arab subjects using optical coherence tomography (OCT. Methods: RNFL thickness and optic disc parameters were obtained in 65 patients aged 50.1 ± 7.7 years. Percentage differences in all parameters were calculated and analyzed between groups. Results: The mean RNFL thickness around the disc and at all quadrants was significantly thinner in glaucomatous eyes than in normal eyes (P < 0.01. The greatest decrease in RNFL thickness was observed at the inferior (39.5% and superior (39.3% quadrants and at 1 o’clock (43% and 5 o’clock (40% hour sectors. Significant differences were observed between glaucomatous and control eyes in all disc parameters (P < 0.005 assessed. The disc area, cup area, mean cup/disc ratio, and vertical and horizontal cup/disc ratios were significantly larger (P < 0.01, whereas the vertical integrated rim area, horizontal integrated rim width, and rim area were significantly smaller (P < 0.001 in glaucomatous eyes than in normal eyes. Conclusion: Stratus OCT is still a valuable tool in the diagnosis of early glaucoma changes and, as such, its use should be encouraged in glaucoma clinics in Saudi Arabia. The best OCT parameters for detecting early glaucoma change were RNFL thickness in the inferior, superior, and 1 o’clock hour sector; the cup area; and the vertical integrated rim area of the optic disc. Keywords: glaucoma, Stratus optical coherence tomography, optic disc, retinal nerve fiber layer (RNFL, age, Saudi Arabia

  8. Numerical simulation of x-ray luminescence optical tomography for small-animal imaging.

    Science.gov (United States)

    Li, Changqing; Martínez-Dávalos, Arnulfo; Cherry, Simon R

    2014-04-01

    X-ray luminescence optical tomography (XLOT) is an emerging hybrid imaging modality in which x-ray excitable particles (phosphor particles) emit optical photons when stimulated with a collimated x-ray beam. XLOT can potentially combine the high sensitivity of optical imaging with the high spatial resolution of x-ray imaging. For reconstruction of XLOT data, we compared two reconstruction algorithms, conventional filtered backprojection (FBP) and a new algorithm, x-ray luminescence optical tomography with excitation priors (XLOT-EP), in which photon propagation is modeled with the diffusion equation and the x-ray beam positions are used as reconstruction priors. Numerical simulations based on dose calculations were used to validate the proposed XLOT imaging system and the reconstruction algorithms. Simulation results showed nanoparticle concentrations reconstructed with XLOT-EP are much less dependent on scan depth than those obtained with FBP. Measurements at just two orthogonal projections are sufficient for XLOT-EP to reconstruct an XLOT image for simple source distributions. The heterogeneity of x-ray energy deposition is included in the XLOT-EP reconstruction and improves the reconstruction accuracy, suggesting that there is a need to calculate the x-ray energy distribution for experimental XLOT imaging. PMID:24695846

  9. Signal simulation and signal processing for multiple reference optical coherence tomography

    Science.gov (United States)

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

    2015-03-01

    The generation of a synthetic MR-OCT signal is presented and compared to a real acquired signal. Multiple reference optical coherence tomography (MR-OCT) is a novel time-domain interferometric system. The MR-OCT principle is adding a partial mirror to extend the axial scan range, which effectively extends the scan depth for imaging. The actuation of the scan mirror required for time-domain OCT, was demonstrated to operate with a low cost miniature voice coil, such as a speaker extracted from a smartphone or CD/DVD pick-up system. Building a compact and cost-effective optical imaging system will enable affordable medical diagnosis at low-resource setting applications. The partial mirror recirculates multiple reflections (orders) into the interferometric system and the increase of optical path delay does increase the beat frequency of the interference signal. The synthesis of such an interference signal using a numerical method is described in this manuscript.

  10. Fiber-Based Polarization Diversity Detection for Polarization-Sensitive Optical Coherence Tomography

    Directory of Open Access Journals (Sweden)

    Hamid Pahlevaninezhad

    2014-09-01

    Full Text Available We present a new fiber-based polarization diversity detection (PDD scheme for polarization sensitive optical coherence tomography (PSOCT. This implementation uses a new custom miniaturized polarization-maintaining fiber coupler with single mode (SM fiber inputs and polarization maintaining (PM fiber outputs. The SM fiber inputs obviate matching the optical lengths of the two orthogonal OCT polarization channels prior to interference while the PM fiber outputs ensure defined orthogonal axes after interference. Advantages of this detection scheme over those with bulk optics PDD include lower cost, easier miniaturization, and more relaxed alignment and handling issues. We incorporate this PDD scheme into a galvanometer-scanned OCT system to demonstrate system calibration and PSOCT imaging of an achromatic quarter-wave plate, fingernail in vivo, and chicken breast, salmon, cow leg, and basa fish muscle samples ex vivo.

  11. Approximate Marginalization of Absorption and Scattering in Fluorescence Diffuse Optical Tomography

    CERN Document Server

    Mozumder, Meghdoot; Arridge, Simon; Kaipio, Jari P; d'Andrea, Cosimo; Kolehmainen, Ville

    2015-01-01

    In fluorescence diffuse optical tomography (fDOT), the reconstruction of the fluorophore concentration inside the target body is usually carried out using a normalized Born approximation model where the measured fluorescent emission data is scaled by measured excitation data. One of the benefits of the model is that it can tolerate inaccuracy in the absorption and scattering distributions that are used in the construction of the forward model to some extent. In this paper, we employ the recently proposed Bayesian approximation error approach to fDOT for compensating for the modeling errors caused by the inaccurately known optical properties of the target in combination with the normalized Born approximation model. The approach is evaluated using a simulated test case with different amount of error in the optical properties. The results show that the Bayesian approximation error approach improves the tolerance of fDOT imaging against modeling errors caused by inaccurately known absorption and scattering of the...

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

    Science.gov (United States)

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

    2010-02-01

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

  13. Extraction of linear anisotropic parameters using optical coherence tomography and hybrid Mueller matrix formalism.

    Science.gov (United States)

    Liao, Chia-Chi; Lo, Yu-Lung

    2015-04-20

    A method is proposed for extracting the linear birefringence (LB) and linear dichroism (LD) properties of an anisotropic optical sample using reflection-mode optical coherence tomography (OCT) and a hybrid Mueller matrix formalism. To ensure the accuracy of the extracted parameter values, a method is proposed for calibrating and compensating the polarization distortion effect induced by the beam splitters in the OCT system using a composite quarter-waveplate / half-waveplate / quarter-waveplate structure. The validity of the proposed method is confirmed by extracting the LB and LD properties of a quarter-wave plate and a defective polarizer. To the best of the authors' knowledge, the method proposed in this study represents the first reported attempt to utilize an inverse Mueller matrix formalism and a reflection-mode OCT structure to extract the LB and LD parameters of optically anisotropic samples. PMID:25969104

  14. Reconstruction methods for sound visualization based on acousto-optic tomography

    DEFF Research Database (Denmark)

    Torras Rosell, Antoni; Lylloff, Oliver

    2013-01-01

    The visualization of acoustic fields using acousto-optic tomography has recently proved to yield satisfactory results in the audible frequency range. The current implementation of this visualization technique uses a laser Doppler vibrometer (LDV) to measure the acousto-optic effect, that is, the interaction between sound and light, over an aperture where the acoustic field is to be investigated. By identifying the relationship between the apparent velocity of the LDV and the Radon transform of the acoustic field, it is possible to reconstruct the sound pressure distribution of the scanned area using tomographic techniques. The filtered back projection (FBP) method is the most popular reconstruction algorithm used for tomography in many fields of science. The present study takes the performance of the FBP method in sound visualization as a reference and investigates the use of alternative methods commonly used in inverse problems, e.g., the singular value decomposition and the conjugate gradient methods. A generic formulation for describing the acousto-optic measurement as an inverse problem is thus derived, and the performance of the numerical methods is assessed by means of simulations and experimental results.

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

    Science.gov (United States)

    Nadhira, Vebi; Kurniadi, Deddy; Juliastuti, E.; Sutiswan, Adeline

    2014-03-01

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

  16. Bone regeneration assessment by optical coherence tomography and MicroCT synchrotron radiation

    Science.gov (United States)

    Negrutiu, Meda L.; Sinescu, Cosmin; Canjau, Silvana; Manescu, Adrian; Topalá, Florin I.; Hoinoiu, Bogdan; Romînu, Mihai; Márcáuteanu, Corina; Duma, Virgil; Bradu, Adrian; Podoleanu, Adrian G.

    2013-06-01

    Bone grafting is a commonly performed surgical procedure to augment bone regeneration in a variety of orthopaedic and maxillofacial procedures, with autologous bone being considered as the "gold standard" bone-grafting material, as it combines all properties required in a bone-graft material: osteoinduction (bone morphogenetic proteins - BMPs - and other growth factors), osteogenesis (osteoprogenitor cells) and osteoconduction (scaffold). The problematic elements of bone regenerative materials are represented by their quality control methods, the adjustment of the initial bone regenerative material, the monitoring (noninvasive, if possible) during their osteoconduction and osteointegration period and biomedical evaluation of the new regenerated bone. One of the research directions was the interface investigation of the regenerative bone materials and their behavior at different time periods on the normal femoral rat bone. 12 rat femurs were used for this investigation. In each ones a 1 mm diameter hole were drilled and a bone grafting material was inserted in the artificial defect. The femurs were removed after one, three and six months. The defects repaired by bone grafting material were evaluated by optical coherence tomography working in Time Domain Mode at 1300 nm. Three dimensional reconstructions of the interfaces were generated. The validations of the results were evaluated by microCT. Synchrotron Radiation allows achieving high spatial resolution images to be generated with high signal-to-noise ratio. In addition, Synchrotron Radiation allows acquisition of volumes at different energies and volume subtraction to enhance contrast. Evaluation of the bone grafting material/bone interface with noninvasive methods such as optical coherence tomography could act as a valuable procedure that can be use in the future in the usual clinical techniques. The results were confirmed by microCT. Optical coherence tomography can be performed in vivo and can provide a qualitative and quantitative evaluation of the bone augmentation procedure.

  17. Fracture process characterization of fiber-reinforced dental composites evaluated by optical coherence tomography, SEM and optical microscopy

    Scientific Electronic Library Online (English)

    Tibério C. U., Matheus; Cynthia M. F., Kauffman; Ana K. S., Braz; Cláudia C. B. O., Mota; Anderson S. L., Gomes.

    Full Text Available This study used optical coherence tomography (OCT) compared to scanning electron microscopy (SEM) and optical microscopy (OM) to evaluate qualitatively crack propagation and final fracture in restorative composite materials - Filtek Z250 and Filtek Z350 (3M ESPE) - with fiber reinforcement after cyc [...] lic loading. Samples were made using a split mold. Initially, 3-point bending tests were performed to determine the maximum force and tension at the fracture moment using samples without fiber reinforcement. Then, mechanical cycling tests were performed using samples with glass fiber embedded internally. The failures were analyzed using the 3 methods described before. OCT permitted good characterization of internal crack propagation of the dental composites, which, however, could not be visualized by either SEM or OM. OCT was proven to be laboratory research tool that is easy to use, does not require any specific preparation of the samples, and is less expensive than SEM.

  18. Investigation of retinal blood flow in glaucoma patients by Doppler Fourier-domain optical coherence tomography

    Science.gov (United States)

    Wang, Yimin; Zhang, Xinbo; Tan, Ou; Huang, David

    2011-03-01

    The measurement of ocular blood flow is important in studying the pathophysiology and treatment of several leading causes of blindness. A pilot study was performed to evaluate the total retinal blood flow in glaucoma patient using Fourier domain optical coherence tomography. For normal people, the measured total retinal flow was between 40.8 and 60.2 ?l/minute. We found that eyes with glaucoma had decreased retinal blood flow and average flow veocity, while the venous cross sectional areas were essentially the same as normal. The decrease in blood flow was highly correlated with the severity of visual field loss.

  19. Evaluation of a multi-wavelength laser array with diffuse optical tomography

    Science.gov (United States)

    Ghijsen, Michael; Zhou, Tiffany; Thayer, David; Gun, Baris; Gulsen, Gultekin

    2010-02-01

    Diffuse Optical Tomography (DOT) is a new and promising medical imaging modality which uses near-infrared light to probe tissue properties. Using multiple wavelengths of light can provide important information about tissue metabolism and cancer malignancy. Unfortunately, in most DOT acquisition schemes, acquiring data for each wavelength has a multiplicative effect on the overall imaging time. In this paper, we evaluate a new multiple wavelength laser module (Praevium Research Inc.) with 12 laser diodes all coupled to a single output fiber. When used in conjunction with a cooled spectrometer, it allows simultaneous multi-wavelength data acquisition and hence, higher temporal resolution.

  20. Polarization-sensitive optical coherence tomography for photoelasticity testing of glass/epoxy composites.

    Science.gov (United States)

    Oh, Jung-Taek; Kim, Seung-Woo

    2003-07-14

    We measure the spatial distribution of the mechanical stress induced inside translucent glass/epoxy composites by means of polarizationsensitive optical coherence tomography. The Stokes parameters determined from two orthogonal polarization components of the backscattered light allow the internal stress to be identified in terms of its magnitude and principal direction based on a birefringence light scattering model of glass/epoxy composites. Measurement examples show the particular case of stress concentration near a through hole and the internal structural damages caused by excessive tensile loading. PMID:19466045

  1. An elegant technique for ex vivo imaging in experimental research—Optical coherence tomography (OCT)

    DEFF Research Database (Denmark)

    Tschernig, T.; Thrane, Lars

    2013-01-01

    Optical coherence tomography (OCT) is an elegant technology for imaging of tissues and organs and has been established for clinical use for around a decade. Thus, it is used in vivo but can also serve as a valuable ex vivo imaging tool in experimental research. Here, a brief overview is given with a focus on an ex vivo application of OCT. Image and video examples of freshly obtained murine lungs are included. The main advantage of OCT for ex vivo analysis is the non-contact, non-invasive, and non-destructive fast acquisition of a three-dimensional data set with micrometer-resolution.

  2. Full-field optical coherence tomography (FFOCT) for evaluation of endometrial cancer

    Science.gov (United States)

    Bruhat, Alexis; Combrinck, Marais; Dalimier, Eugénie; Harms, Fabrice; Fine, Jeffrey L.

    2015-02-01

    Full-field optical coherence tomography (FFOCT) quickly produces images that resemble conventional pathology images. We examined endometrium in an intra-operative like fashion (more than forty samples). FFOCT-imaged endometrium was recognizable to pathologists and compared favorably with microscopy of the same samples. Additional image enhancements and acquisition techniques were explored and may improve interpretation accuracy. Wider evaluation of images is ongoing, using more pathologist subjects. FFOCT may revolutionize pathology practice in the future by permitting rapid diagnosis and in vivo diagnosis; this is potentially a disruptive new diagnostic technique in pathology.

  3. Novel combined miniature optical coherence tomography ultrasound probe for in vivo intravascular imaging

    OpenAIRE

    Yin, Jiechen; Li, Xiang; Jing, Joe; Li, Jiawen; Mukai, David; Mahon, Sari; Edris, Ahmad; Hoang, Khiet; SHUNG, K. KIRK; Brenner, Matthew; Narula, Jagat; Zhou, Qifa; Chen, Zhongping

    2011-01-01

    We have developed a miniature integrated optical coherence tomography (OCT) ultrasound (US) probing system for intravascular imaging applications. In the OCT probe, the light coming out of a single mode fiber is focused by a gradient-index lens and then reflected by a right-angle prism from the side of the probe into the sample. It was combined with a 35 MHz PMN-PT side-viewing ultrasound transducer to obtain the ultrasound image as well. The OCT and ultrasound probes were integrated as a sin...

  4. Imaging late capsular bag distension syndrome: an anterior segment optical coherence tomography study

    OpenAIRE

    Yl, Tan; Ls, Mohanram; Se, Ti; Aung T; Perera S

    2012-01-01

    Yar Li Tan,1,2 Lakshmanasamudram S Mohanram,1 Seng Ei Ti,1,2 Tin Aung,1–3 Shamira Perera1,21Singapore National Eye Centre, 2Singapore Eye Research Institute, 3National University of Singapore, Yong Loo Lin School of Medicine, Buona Vista, SingaporeBackground: Anterior segment optical coherence tomography (ASOCT) was used to categorize and provide insights into the etiology of capsular bag distension syndrome (CBDS).Methods: A prospective review was undertaken of 10 cases who present...

  5. Comparative analysis of combined spectral and optical tomography methods for detection of skin and lung cancers

    Science.gov (United States)

    Zakharov, Valery P.; Bratchenko, Ivan A.; Artemyev, Dmitry N.; Myakinin, Oleg O.; Kornilin, Dmitry V.; Kozlov, Sergey V.; Moryatov, Alexander A.

    2015-02-01

    Malignant skin tumors of different types were studied in vivo using optical coherence tomography (OCT), backscattering (BS), and Raman spectroscopy (RS). A multimodal method is proposed for early cancer detection based on complex analysis of OCT images by their relative alteration of scattered-radiation spectral intensities between malignant and healthy tissues. An increase in average accuracy of diagnosis was observed for a variety of cancer types (9% sensitivity, 8% specificity) by a multimodal RS-BS-OCT system in comparison with any of the three methods used separately. The proposed approach equalizes the processing rates for all methods and allows for simultaneous imaging and classification of tumors.

  6. Dynamic diffuse optical tomography for assessing changes of breast tumors during neoadjuvant chemotherapy

    Science.gov (United States)

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

    2015-03-01

    We have developed a dynamic diffuse optical tomography imaging system that is capable of 3D imaging of both breasts simultaneously. In an ongoing study subjects receiving neoadjuvant chemotherapy are imaged at 6 time points throughout their 5-month treatment. At each time point the subjects preform a breath hold to observe the hemodynamic effects in the breasts. For each session the percent change of various hemodynamic parameters during the breath hold is determined. Preliminary results from show statistically significant differences in washout rates and deoxyhemoglobin changes at the 2-week imaging point between subjects that respond and do not respond to treatment.

  7. Ultrahigh resolution optical coherence tomography with femtosecond Ti:sapphire laser and photonic crystal fiber

    OpenAIRE

    Ping, XUE; Fujimoto, James G.

    2008-01-01

    Optical coherence tomography (OCT) with ultrahigh axial resolution was achieved by the super-continuum generated by coupling femtosecond pulses from a commercial Ti:sapphire laser into an air-silica microstructure fiber. The visible spectrum of the super-continuum from 450 to 700 nm centered at 540 nm can be generated. A free-space axial OCT resolution of 0.64 ?m was achieved. The sensitivity of OCT system was 108 dB with incident light power 3 mW at sample, only 7dB below the theoretical lim...

  8. Precise measurement of instantaneous 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). We propose a method for extraction of the target eccrine sweat gland by use of the connected component extraction process and the adaptive threshold method, where the en-face OCT images are constructed by the SS-OCT. Furthermore, we demonstrate precise measurement of instantaneous volume of the sweat gland in response to the external stimulus. The dynamic change of instantaneous volume of eccrine sweat gland in mental sweating is performed by this method during the period of 300 sec with the frame intervals of 3.23 sec.

  9. A one step vs. a multi step geometric calibration of an optical coherence tomography

    Science.gov (United States)

    Díaz Díaz, Jesús; Rahlves, Maik; Majdani, Omid; Reithmeier, Eduard; Ortmaier, Tobias

    2013-03-01

    This contribution compares two approaches for the geometric calibration of an optical coherence tomography (OCT) which forms part of a medical navigation system. For this purpose, a one step and a multi step calibration is performed with a self-produced 3D reference structure and a high-accurate 6 degrees of freedom (DoF) parallel robot, respectively. These 3D landmark-based geometric calibrations are based on the identification of a parameterized grey-box OCT model. We show in experimental results that both methods reduce systematic errors by more than one order of magnitude.

  10. Simultaneous dual wavelength eye-tracked ultrahigh resolution retinal and choroidal optical coherence tomography

    DEFF Research Database (Denmark)

    Unterhuber, A.; Povaay, B.

    2013-01-01

    We demonstrate an optical coherence tomography device that simultaneously combines different novel ultrabroad bandwidth light sources centered in the 800 and 1060 nm regions, operating at 66 kHz depth scan rate, and a confocal laser scanning ophthalmoscope-based eye tracker to permit motion-artifact-free, ultrahigh resolution and high contrast retinal and choroidal imaging. The two wavelengths of the device provide the complementary information needed for diagnosis of subtle retinal changes, while also increasing visibility of deeper-lying layers to image pathologies that include opaque media in the anterior eye segment or eyes with increased choroidal thickness.

  11. Comparison of diffusion approximation and higher order diffusion equations for optical tomography of osteoarthritis

    Science.gov (United States)

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

    2009-09-01

    In this study, a simplified spherical harmonics approximated higher order diffusion model is employed for 3-D diffuse optical tomography of osteoarthritis in the finger joints. We find that the use of a higher-order diffusion model in a stand-alone framework provides significant improvement in reconstruction accuracy over the diffusion approximation model. However, we also find that this is not the case in the image-guided setting when spatial prior knowledge from x-rays is incorporated. The results show that the reconstruction error between these two models is about 15 and 4%, respectively, for stand-alone and image-guided frameworks.

  12. A method for obtaining scattering decomposed images in optical coherence tomography

    International Nuclear Information System (INIS)

    A method for obtaining scattering decomposed images in optical coherence tomography based on a multiple scattering model is proposed. Images of different scattering components can be obtained with this method. Employing the proposed method, scattering decomposed images of a biological sample are obtained. Then spatial mean filtering for denoising is performed on only the multiple scattering component, and the total signal is reconstructed. This method is useful for observing the images of different scattering components and has the potential to be applied to information extraction or signal processing on these components separately. (paper)

  13. Full-range k-domain linearization in spectral-domain optical coherence tomography

    OpenAIRE

    Jeon, Mansik; Kim, Jeehyun; Jung, Unsang; Lee, Changho; Jung, Woonggyu; Boppart, Stephen A.

    2011-01-01

    A full-bandwidth k-domain linearization method for spectral-domain optical coherence tomography (SD-OCT) is demonstrated. The method uses information of the wavenumber–pixel-position provided by a translating-slit-based wavelength filter. For calibration purposes, the filter is placed either after a broadband source or at the end of the sample path, and the filtered spectrum with a narrowed line width (~0.5 nm) is incident on a line-scan camera in the detection path. The wavelength-swept sp...

  14. Mode-filtered large-core fiber for optical coherence tomography

    OpenAIRE

    Moon, Sucbei; Chen, Zhongping

    2012-01-01

    We have investigated the use of multimode fiber in optical coherence tomography (OCT) with a mode filter that selectively suppresses the power of the high-order modes (HOMs). A large-core fiber (LCF) that has a moderate number of guiding modes was found to be an attractive alternative to the conventional single-mode fiber for its large mode area and the consequentially wide Rayleigh range of the output beam if the HOMs of the LCF were efficiently filtered out by a mode filter installed in the...

  15. Gold nanorods tailored as tracers for sentinel lymph node biopsy imaged by photothermal optical coherence tomography

    Science.gov (United States)

    Jung, Yeongri; Wang, Ruikang K.

    2011-03-01

    Gold nanorods (GNRs) have been demonstrated as a scattering imaging agent or therapeutic agent. Because of their narrow window, biocompatibility, and uniform small size for blood circulation, GNRs are well suited to serve as imaging contrast agents. Especially, strong phothothermal (PT) effect is attractive for diagnostic (e.g. sentinel lymph node biopsy) or therapeutic (e.g. PT therapy) purposes. In this paper, we demonstrate GNRs as multipurpose agents with PT-optical coherence tomography (OCT) for imaging sentinel lymph node. The results show that GNRs are promising for imaging contrast enhancement for visualizing the detailed functions of SLN.

  16. Two-dimensional optical coherence tomography for real-time structural dynamical characterization

    Science.gov (United States)

    Zhong, Jianfeng; Zhong, Shuncong; Zhang, Qiukun; Yao, Ligang

    2015-03-01

    We present a two-dimensional optical coherence vibration tomography (2DOCVT) system with an ultra-precision displacement resolution of ~0.1 nm that is capable of in site real-time absolute displacement measurement of structural line vibrations. Experimental results of sinusoidal, sweep and impulse vibrations were reported. The key figures of merit such as the 2DOCVT system could obtain fast line vibration measurement without scanning and it also could be used to capture structural modal parameters in one single impulse excitation measurement without any vibration excitation input information, making it attractive for the application in low-frequency vibration measurement and response-only modal analysis.

  17. Advances in clinical application of optical coherence tomography in vitreomacular interface disease

    Directory of Open Access Journals (Sweden)

    Xiao-Li Xing

    2013-08-01

    Full Text Available Vitreous macular interface disease mainly includes vitreomacular traction syndrome, idiopathic macular epiretinal membrane and idiopathic macular hole. Optical coherence tomography(OCTas a new tool that provides high resolution biopsy cross section image non traumatic imaging inspection, has a unique high resolution, no damage characteristics, and hence clinical widely used, vitreous macular interface for clinical disease diagnosis, differential diagnosis and condition monitoring and quantitative evaluation, treatment options, etc provides important information and reference value. Vitreous macular interface disease in OCT image of anatomical morphology characteristics, improve the clinical on disease occurrence and development of knowledge. We reviewed the advances in the application of OCT in vitreomacular interface disease.

  18. High-speed polarization-sensitive optical coherence tomography for the investigation of tissue birefringence

    Science.gov (United States)

    Gulsen, Gultekin; Nalcioglu, Orhan

    2005-04-01

    Polarization-sensitive optical coherence tomography (PSOCT) is an optical imaging modality that is sensitive to the birefringence properties of tissues. Birefringence is related to various biological components and therefore, polarization can provide novel contrast mechanisms for imaging. In this work, we will describe the design of a high-speed polarization sensitive optical coherence tomography system. A broadband source centered at 1310nm with 35nm bandwidth was utilized as the light source. The output power of the source and the resolution of the system were around 20mW and ~20 micrometers, respectively. To achieve high-speed scan, a rapid scan optical delay line (RSOD) was utilized in the reference arm. It provided depth scanning up to 1000 A-scan/s and controlled the carrier frequency of the interference of fridge pattern. Two galvo-mounted mirrors were used for lateral scanning of the beam. The polarization state of the incident light was altered between horizontal and vertical states by using a fast polarization rotator. The combined light from the reference and the sample arms was split into two orthogonal polarization components by a polarizing beam splitter and coupled into two single-mode optical fibers that are connected to the photodiodes. The roundtrip Jones matrix of the sample arm was measured and used to calibrate the measurements of polarization properties of the sample. The elements of the Jones matrix of the sample were calculated by the using the output Jones vectors for the incident polarization states. The performance of the system was evaluated with standard samples such as a quarter-wave plate. The animal studies are currently undertaken to assess the performance of the system in-vivo.

  19. Optical computed tomography of radiochromic gels for accurate three-dimensional dosimetry

    Science.gov (United States)

    Babic, Steven

    In this thesis, three-dimensional (3-D) radiochromic Ferrous Xylenol-orange (FX) and Leuco Crystal Violet (LCV) micelles gels were imaged by laser and cone-beam (Vista(TM)) optical computed tomography (CT) scanners. The objective was to develop optical CT of radiochromic gels for accurate 3-D dosimetry of intensity-modulated radiation therapy (IMRT) and small field techniques used in modern radiotherapy. First, the cause of a threshold dose response in FX gel dosimeters when scanned with a yellow light source was determined. This effect stems from a spectral sensitivity to multiple chemical complexes that are at different dose levels between ferric ions and xylenol-orange. To negate the threshold dose, an initial concentration of ferric ions is needed in order to shift the chemical equilibrium so that additional dose results in a linear production of a coloured complex that preferentially absorbs at longer wavelengths. Second, a low diffusion leuco-based radiochromic gel consisting of Triton X-100 micelles was developed. The diffusion coefficient of the LCV micelle gel was found to be minimal (0.036 + 0.001 mm2 hr-1 ). Although a dosimetric characterization revealed a reduced sensitivity to radiation, this was offset by a lower auto-oxidation rate and base optical density, higher melting point and no spectral sensitivity. Third, the Radiological Physics Centre (RPC) head-and-neck IMRT protocol was extended to 3-D dose verification using laser and cone-beam (Vista(TM)) optical CT scans of FX gels. Both optical systems yielded comparable measured dose distributions in high-dose regions and low gradients. The FX gel dosimetry results were crossed checked against independent thermoluminescent dosimeter and GAFChromicRTM EBT film measurements made by the RPC. It was shown that optical CT scanned FX gels can be used for accurate IMRT dose verification in 3-D. Finally, corrections for FX gel diffusion and scattered stray light in the Vista(TM) scanner were developed to enable accurate acquisition of small beam dosimetric parameters for treatment planning commissioning. By applying these corrections, optically CT scanned FX and LCV gel dose measurements were found to be in agreement with reference GAFChromicRTM EBT film measurements. In conclusion, once specific problems affecting radiochromic gel materials and optical CT scanners are well understood and resolved, accurate 3-D dosimetry can be achieved. Ultimately, this will facilitate the safe clinical implementation of novel radiation treatments of cancer. Keywords. three-dimensional dosimetry, ferrous xylenol-orange gels, leuco crystal violet micelle gels, optical computed tomography, laser scanner, Vista(TM) cone-beam scanner, intensity-modulated radiation therapy, small field dosimetry.

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Aigner, M., E-mail: michael.aigner@jku.at; Köpplmayr, T., E-mail: thomas.koepplmayr@jku.at, E-mail: Christian.lang@jku.at; Lang, C., E-mail: thomas.koepplmayr@jku.at, E-mail: Christian.lang@jku.at; Burzic, I., E-mail: ivana.burzic@jku.at, E-mail: juergen.miethlinger@jku.at; Miethlinger, J., E-mail: ivana.burzic@jku.at, E-mail: juergen.miethlinger@jku.at [Institute of Polymer Extrusion and Compounding, Johannes Kepler University Linz (Austria); Salaberger, D., E-mail: dietmar.salaberger@fh-wels.at [University of Applied Sciences Upper Austria (Austria); Buchsbaum, A., E-mail: andreas.buchsbaum@recendt.at; Leitner, M. [Research Center for Non Destructive Testing GmbH (Austria); Heise, B., E-mail: bettina.heise@jku.at [Christian Doppler Laboratory for Microscopic and Spectroscopic Material Characterization, ZONA, Austria and Institute for Knowledge-based Mathematical Systems, Johannes Kepler University Linz (Austria); Schausberger, S. E., E-mail: stefan.schausberger@jku.at; Stifter, D. [Christian Doppler Laboratory for Microscopic and Spectroscopic Material Characterization, ZONA (Austria)

    2014-05-15

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

  2. Novel electro-optical coupling technique for magnetic resonance-compatible positron emission tomography detectors.

    Science.gov (United States)

    Olcott, Peter D; Peng, Hao; Levin, Craig S

    2009-01-01

    A new magnetic resonance imaging (MRI)-compatible positron emission tomography (PET) detector design is being developed that uses electro-optical coupling to bring the amplitude and arrival time information of high-speed PET detector scintillation pulses out of an MRI system. The electro-optical coupling technology consists of a magnetically insensitive photodetector output signal connected to a nonmagnetic vertical cavity surface emitting laser (VCSEL) diode that is coupled to a multimode optical fiber. This scheme essentially acts as an optical wire with no influence on the MRI system. To test the feasibility of this approach, a lutetium-yttrium oxyorthosilicate crystal coupled to a single pixel of a solid-state photomultiplier array was placed in coincidence with a lutetium oxyorthosilicate crystal coupled to a fast photomultiplier tube with both the new nonmagnetic VCSEL coupling and the standard coaxial cable signal transmission scheme. No significant change was observed in 511 keV photopeak energy resolution and coincidence time resolution. This electro-optical coupling technology enables an MRI-compatible PET block detector to have a reduced electromagnetic footprint compared with the signal transmission schemes deployed in the current MRI/PET designs. PMID:19397853

  3. Feasibility of interstitial diffuse optical tomography using cylindrical diffusing fibers for prostate PDT

    International Nuclear Information System (INIS)

    Interstitial diffuse optical tomography (DOT) has been used to characterize spatial distribution of optical properties for prostate photodynamic therapy (PDT) dosimetry. We have developed an interstitial DOT method using cylindrical diffuse fibers (CDFs) as light sources, so that the same light sources can be used for both DOT measurement and PDT treatment. In this novel interstitial CDF-DOT method, absolute light fluence per source strength (in unit of 1 cm?2) is used to separate absorption and scattering coefficients. A mathematical phantom and a solid prostate phantom including anomalies with known optical properties were used, respectively, to test the feasibility of reconstructing optical properties using interstitial CDF-DOT. Three dimension spatial distributions of the optical properties were reconstructed for both scenarios. Our studies show that absorption coefficient can be reliably extrapolated while there are some cross talks between absorption and scattering properties. Even with the suboptimal reduced scattering coefficients, the reconstructed light fluence rate agreed with the measured values to within ±10%, thus the proposed CDF-DOT allows greatly improved light dosimetry calculation for interstitial PDT. (paper)

  4. Signal attenuation and localization in optical coherence tomography studied by Monte Carlo simulation

    International Nuclear Information System (INIS)

    A Monte Carlo model has been developed for optical coherence tomography (OCT). A geometrical optics implementation of the OCT probe with low-coherence interferometric detection was combined with three-dimensional stochastic Monte Carlo modelling of photon propagation in the homogeneous sample medium. Optical properties of the sample were selected to simulate intralipid and blood, representing moderately (g=0.7) and highly (g=0.99) anisotropic scattering respectively. For shallow optical depths in simulated intralipid (<3 scattering mean free path (mfp) units), the number of detected backscattered photons followed the extinction-single-backscatter model, and OCT was found to detect only minimally scattered photons. Within this depth range the backscatter positions of detected photons corresponded well with the nominal focus position of the probe. For propagation to deeper positions in intralipid, localization of backscattering was quickly lost due to detection of stray photons, and the number of detected photons remained constant with increasing depth in the non-absorbing medium. For strongly forward-directed scattering in simulated blood, the number of detected photons approached the extinction-single-backscatter model only for very shallow depths (<2 mfp units). However, backscattering positions for detected photons correlated well with the nominal focus position of the probe even for optical depths greater than 40 mfp units. (author) (author)

  5. Ultrasound modulated optical tomography contrast enhancement with non-linear oscillation of microbubbles

    Science.gov (United States)

    Ruan, Haowen; Mather, Melissa L.

    2015-01-01

    Background Ultrasound modulated optical tomography (USMOT) is an imaging technique used to provide optical functional information inside highly scattering biological tissue. One of the challenges facing this technique is the low image contrast. Methods A contrast enhancement imaging technique based on the non-linear oscillation of microbubbles is demonstrated to improve image contrast. The ultrasound modulated signal was detected using a laser pulse based speckle contrast detection system. Better understanding of the effects of microbubbles on the optical signals was achieved through simultaneous measurement of the ultrasound scattered by the microbubbles. Results The length of the laser pulse was found to affect the system response of the speckle contrast method with shorter pulses suppressing the fundamental ultrasound modulated optical signal. Using this property, image contrast can be enhanced by detection of the higher harmonic ultrasound modulated optical signals due to nonlinear oscillation and destruction of the microbubbles. Experimental investigations were carried out to demonstrate a doubling in contrast by imaging a scattering phantom containing an embedded silicone tube with microbubbles flowing through it. Conclusions The contrast enhancement in USMOT resulting from the use of ultrasound microbubbles has been demonstrated. Destruction of the microbubbles was shown to be the dominant effect leading to contrast improvement as shown by simultaneously detecting the ultrasound and speckle contrast signals. Line scans of a microbubble filled silicone tube embedded in a scattering phantom demonstrated experimentally the significant image contrast improvement that can be achieved using microbubbles and demonstrates the potential as a future clinical imaging tool. PMID:25694948

  6. Structure-Function Relationship between Frequency-Doubling Technology Perimetry and Optical Coherence Tomography in Glaucoma.

    Science.gov (United States)

    Fuertes-Lazaro, Isabel; Sanchez-Cano, Ana; Ferreras, Antonio; Ferrandez, Blanca; Calvo, Pilar; Abadia, Beatriz; Otin, Sofia; Pablo, Luis E

    2014-11-26

    Purpose: To assess the relationship between the retinal nerve fibre layer (RNFL) thickness and the frequency-doubling technology perimetry (FDT) outcome. Methods: Sixty-two healthy individuals and 72 glaucoma patients were prospectively selected. All participants underwent a reliable FDT and optical coherence tomography (OCT). Pearson correlations were calculated between the unlogged threshold values of FDT and RNFL thicknesses measured by OCT. Results: Mild to moderate correlations were found between a few points from FDT and RNFL thicknesses in the vertical axis. The nasal superior area of FDT and the RNFL thickness at the 7-o'clock position had the strongest correlation (0.434, p optic neuropathy. The map obtained validates previously reported clinical findings and contributes to a better understanding of the structure-function relationship in glaucoma. © 2014 S. Karger AG, Basel. PMID:25427775

  7. Monte Carlo simulation of an optical coherence tomography signal in homogeneous turbid media

    International Nuclear Information System (INIS)

    The Monte Carlo technique with angle biasing is used to simulate the optical coherence tomography (OCT) signal from homogeneous turbid media. The OCT signal is divided into two categories: one is from a target imaging layer in the medium (Class I); the other is from the rest of the medium (Class II). These two classes of signal are very different in their spatial distributions, angular distributions and the numbers of experienced scattering events. Multiply scattered light contributes to the Class I signal as well as the Class II signal. The average number of scattering events increases linearly with the probing depth. The Class II signal decays much more slowly than the Class I signal whose decay constant is close to the total attenuation coefficient of the turbid medium. The effect of the optical properties of the medium on the Class I signal decay is studied. (author)

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

    Science.gov (United States)

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

    2011-10-01

    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 imaged using this hybrid system. For the first time, enhancement kinetics of the exogenous contrast ICG is recovered from the DCE-DOT data using MR anatomical a priori information. As tumors grow, they undergo necrosis and the tissue transforms from viable to necrotic. The results show that the physiological changes between viable and necrotic tissue can be differentiated more accurately based on the ICG enhancement kinetics when MR anatomical information is utilized.

  9. Dimensional quality control of Ti-Ni dental file by optical coordinate metrology and computed tomography

    DEFF Research Database (Denmark)

    Yagüe-Fabra, J.A.; Tosello, Guido

    2014-01-01

    Endodontic dental files usually present complex 3D geometries, which make the complete measurement of the component very challenging with conventional micro metrology tools. Computed Tomography (CT) can represent a suitable alternative solution to micro metrology tools based on optical and tactile techniques. However, the establishment of CT systems traceability when measuring 3D complex geometries is still an open issue. In this work, to verify the quality of the CT dimensional measurements, the dental file has been measured both with a ?CT system and an optical CMM (OCMM). The uncertainty of measurements performed with both technologies is assessed. The estimated uncertainty is eventually compared with the component’s calibration and tolerances to validate the measuring capability of the ?CT system.

  10. A Near-Infrared Optical Tomography System Based on Photomultiplier Tube

    Directory of Open Access Journals (Sweden)

    Jing Bai

    2007-07-01

    Full Text Available Diffuse optical tomography (DOT is a rapidly growing discipline in recent years. It plays an important role in many fields, such as detecting breast cancer and monitoring the cerebra oxygenation. In this paper, a relatively simple, inexpensive, and conveniently used DOT system is presented in detail, in which only one photomultiplier tube is employed as the detector and an optical multiplexer is used to alter the detector channels. The 32-channel imager is consisted of 16-launch fibers and 16-detector fibers bundles, which works in the near-infrared (NIR spectral range under continuous-wave (CW model. The entire imaging system can work highly automatically and harmoniously. Experiments based on the proposed imaging system were performed, and the desired results can be obtained. The experimental results suggested that the proposed imaging instrumentation is effective.

  11. Cryosurgery treatment of actinic keratoses monitored by optical coherence tomography : A pilot study

    DEFF Research Database (Denmark)

    Themstrup, L.; Banzhaf, C.

    2013-01-01

    Background: Optical coherence tomography (OCT) is a non-invasive optical imaging technique providing high-resolution images. OCT may be useful as a monitoring tool during treatment of actinic keratoses (AK) and skin cancer. Objective: To examine and describe how OCT skin morphology changes when the tissue is exposed to the effects of cryotherapy. Methods: Normal ex vivo skin and in vivo AK lesions were examined. Cryotherapy was applied and OCT images were acquired at defined time points. OCT morphology was described. Results: Cryotherapy treatment produced an opaque iceball, and freezing depth could not be monitored by OCT. Vesicle formation after cryotherapy could be identified in OCT images. In ex vivo skin no vesicle formation occurred. Conclusion: OCT cannot monitor the freezing depth, but OCT was able to visualise AK lesions and vesicle formation shortly after cryotherapy. Results add to the assumption that OCT could be used in monitoring non-invasive treatments. © 2012 S. Karger AG, Basel.

  12. Real-time intraoperative spectral domain optical coherence tomography for vitreoretinal surgery

    Science.gov (United States)

    Tao, Yuankai K.; Toth, Cynthia A.; Izatt, Joseph A.

    2010-02-01

    Vitreoretinal surgery visualization is inherently limited by the ability to distinguish between tissues with subtle contrast, and to judge the location of an object relative to other retinal substructures. Inherent issues in visualizing thin translucent tissues, in contrast to underlying semitransparent ones, require the use of stains such as indocyanine green, which is toxic to retinal tissue. Spectral domain optical coherence tomography (SDOCT) has demonstrated strong clinical success in retinal imaging, enabling high-resolution, motion-artifact-free cross-sectional imaging and rapid accumulation of volumetric macular datasets. Current generation SDOCT systems achieve Oculus Binocular Indirect Ophthalmo-Microscope (BIOM3) suspended from a Leica microscope with SDOCT scanning and relay optics, we have demonstrated real-time cross-sectional imaging of multiple layers of the retinal structure, allowing for SDOCT augmented intrasurgical microscopy for intraocular visualization.

  13. Real-time correction of geometric distortion artefacts in large-volume optical coherence tomography

    International Nuclear Information System (INIS)

    Large-volume optical coherence tomography (OCT) setups employ scanning mirrors and suffer from geometric distortion artefacts in which the degree of distortion is determined by the maximum angles over which the mirrors rotate. In this note, we describe a straightforward coordinate transformation scheme to correct for these artefacts in three dimensions, creating an alternative to previously reported ray-tracing schemes. We demonstrate that this recalibration procedure can be applied in real time by implementing the proposed algorithm on the graphics card of a standard computer, making it useful for topography applications. The accuracy of the proposed calibration procedure is validated over an imaging volume of 12.35×10.13×2.36 mm3 using optical moiré measurements of a highly curved object. (technical design note)

  14. Single mode fiber based polarization sensitive optical coherence tomography using a swept laser source

    International Nuclear Information System (INIS)

    We report the development of a near real time single mode fiber-optic based polarization sensitive optical coherence tomography (PSOCT) setup utilizing a swept source. The setup has a polarization modulator (PM) and polarizer in a sample arm to serve as a polarization state generator and analyzer. Since only intensity information is used to retrieve the polarization parameters of the sample, the problem of phase jitters present in the swept source is avoided. Further, the use of polarization elements after the sample arm fiber makes the approach insensitive to the random birefringence of fibers. The swept source based PSOCT (SS-PSOCT) setup was calibrated by carrying out measurements on a quarter-wave plate whose fast axis orientation was rotated from 0° to 360° in steps of 10°. The setup has been used for imaging birefringence of mice tail tendon, thigh muscle ex vivo and human nail fold in vivo

  15. Algorithm optimization for quantitative analysis of intravascular optical coherence tomography data

    Science.gov (United States)

    van Soest, Gijs; Goderie, Thadé P. M.; van Noorden, Sander; van der Steen, Anton F. W.

    2009-02-01

    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, permitting 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. We developed a framework to aid the recognition of these atherosclerotic plaque constituents, based on the optical attenuation coefficient of the tissue. Based on a single-scattering model and using the point spread functions of individually characterized imaging catheters, several parameters need to be set in the analysis that may influence the results. Here, we present a simulation study used to optimize these parameters.

  16. Ultra-compact silicon photonic integrated interferometer for swept-source optical coherence tomography.

    Science.gov (United States)

    Yurtsever, Günay; Weiss, Nicolás; Kalkman, Jeroen; van Leeuwen, Ton G; Baets, Roel

    2014-09-01

    We demonstrate an ultra-compact silicon integrated photonic interferometer for swept-source optical coherence tomography (SS-OCT). The footprint of the integrated interferometer is only 0.75×5??mm2. The design consists of three 2×2 splitters, a 13 cm physical length (50.4 cm optical length) reference arm, and grating couplers. The photonic integrated circuit was used as the interferometer of an SS-OCT system. The sensitivity of the system was measured to be -62??dB with 115 ?W power delivered to the sample. Using the system, we demonstrate cross-sectional OCT imaging of a layered tissue phantom. We also discuss potential improvements in passive silicon photonic integrated circuit design and integration with active components. PMID:25166116

  17. Observation and analysis on skin cancer induced by UVB irradiation using optical coherence tomography

    Science.gov (United States)

    Wang, Yunxia; Wu, Shulian; Li, Hui; Zheng, Xiaoxiao

    2014-09-01

    Basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) are the prevalent skin cancers, which have a quite high incidence in the white race. In recent years, however, their incidences have been increasing in the yellow race, resulting in a great threat to the public health. According to researches, chronics UVB irradiation (280nm~320nm) is the major culprit of skin cancer in humans. In our study, the model of UVB induced skin cancer was established firstly. Optical coherence tomography (OCT) combined with the histopathology was exploited to monitor the morphologic and histological changes of the process of UVB induced skin cancer. Meanwhile, this canceration process was systematically studied and analyzed from the perspective of tissue optics. The attenuation coefficient (?t) has a rising trend in the epidermis, but which shows a downward trend in the dermis. The results are conducive to understand the process of UVB-induced skin cancer and further be able to provide a reference for medical researchers.

  18. A joint estimation detection of Glaucoma progression in 3D spectral domain optical coherence tomography optic nerve head images

    Science.gov (United States)

    Belghith, Akram; Bowd, Christopher; Weinreb, Robert N.; Zangwill, Linda M.

    2014-03-01

    Glaucoma is an ocular disease characterized by distinctive changes in the optic nerve head (ONH) and visual field. Glaucoma can strike without symptoms and causes blindness if it remains without treatment. Therefore, early disease detection is important so that treatment can be initiated and blindness prevented. In this context, important advances in technology for non-invasive imaging of the eye have been made providing quantitative tools to measure structural changes in ONH topography, an essential element for glaucoma detection and monitoring. 3D spectral domain optical coherence tomography (SD-OCT), an optical imaging technique, has been commonly used to discriminate glaucomatous from healthy subjects. In this paper, we present a new framework for detection of glaucoma progression using 3D SD-OCT images. In contrast to previous works that the retinal nerve fiber layer (RNFL) thickness measurement provided by commercially available spectral-domain optical coherence tomograph, we consider the whole 3D volume for change detection. To integrate a priori knowledge and in particular the spatial voxel dependency in the change detection map, we propose the use of the Markov Random Field to handle a such dependency. To accommodate the presence of false positive detection, the estimated change detection map is then used to classify a 3D SDOCT image into the "non-progressing" and "progressing" glaucoma classes, based on a fuzzy logic classifier. We compared the diagnostic performance of the proposed framework to existing methods of progression detection.

  19. Spectral domain optical coherence tomography documented rapid resolution of pseudophakic cystoid macular edema with topical difluprednate

    Directory of Open Access Journals (Sweden)

    Chalam KV

    2012-01-01

    Full Text Available KV Chalam, Vijay Khetpal, Chirag J PatelDepartment of Ophthalmology, University of Florida Jacksonville, FL, USAIntroduction: Pseudophakic cystoid macular edema is a common cause of poor vision after cataract surgery, and topical corticosteroids and nonsteroidal anti-inflammatory drugs are used for its treatment. We investigated the effectiveness of difluprednate (Durezol®, recently approved by the US Food and Drug Administration in the treatment of cystoid macular edema, assisted with spectral domain optical coherence tomography (SD-OCT.Case report: A 63-year-old African-American woman presented 6 weeks after uneventful cataract surgery in her left eye with decreased vision and associated distortion of the central visual field. Fluorescein angiogram and SD-OCT confirmed pseudophakic cystoid macular edema. Difluprednate was topically administered twice daily and monitored with serial imaging. Resolution was noted after 1 month of topical therapy, with improvement in visual acuity and resolution of distortion.Conclusion: Difluprednate is an effective treatment for patients with severe pseudophakic cystoid macular edema. SD-OCT allows the physician to monitor resolution of the macular edema easily.Keywords: cystoid macular edema, difluprednate, spectral domain optical coherence tomography, pseudophakic

  20. Fluorescence diffuse optical tomography with functional and anatomical a priori information: feasibility study

    International Nuclear Information System (INIS)

    Fluorescence diffuse optical tomography (FT) is an emerging molecular imaging technique that can spatially resolve both fluorophore concentration and lifetime parameters. In this study, we investigate the performance of a frequency-domain FT system for small inclusions that are embedded in a heterogeneous background. The results demonstrate that functional and structural a priori information is crucial to be able to recover both parameters with high accuracy. The functional a priori information is defined by the absorption and scattering maps at both excitation and emission wavelengths. Similarly, the boundaries of the small inclusion and different regions in the background are utilized as the structural a priori information. Without a priori information, the fluorophore concentration of a 5 mm inclusion in a 40 mm medium is recovered with 50% error, while the lifetime cannot be recovered at all. On the other hand, when both functional and structural information are available, the true lifetime can be recovered and the fluorophore concentration can be estimated only with 5% error. This study shows that a hybrid system that can acquire diffuse optical absorption tomography (DOT), FT and anatomical images in the same setting is essential to be able to recover the fluorophore concentration and lifetime accurately in vivo

  1. Fluorescence diffuse optical tomography with functional and anatomical a priori information: feasibility study

    Science.gov (United States)

    Lin, Y.; Gao, H.; Nalcioglu, O.; Gulsen, G.

    2007-09-01

    Fluorescence diffuse optical tomography (FT) is an emerging molecular imaging technique that can spatially resolve both fluorophore concentration and lifetime parameters. In this study, we investigate the performance of a frequency-domain FT system for small inclusions that are embedded in a heterogeneous background. The results demonstrate that functional and structural a priori information is crucial to be able to recover both parameters with high accuracy. The functional a priori information is defined by the absorption and scattering maps at both excitation and emission wavelengths. Similarly, the boundaries of the small inclusion and different regions in the background are utilized as the structural a priori information. Without a priori information, the fluorophore concentration of a 5 mm inclusion in a 40 mm medium is recovered with 50% error, while the lifetime cannot be recovered at all. On the other hand, when both functional and structural information are available, the true lifetime can be recovered and the fluorophore concentration can be estimated only with 5% error. This study shows that a hybrid system that can acquire diffuse optical absorption tomography (DOT), FT and anatomical images in the same setting is essential to be able to recover the fluorophore concentration and lifetime accurately in vivo.

  2. Fluorescence diffuse optical tomography with functional and anatomical a priori information: feasibility study

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Y; Gao, H; Nalcioglu, O; Gulsen, G [Tu and Yuen Center for Functional Onco Imaging, University of California, Irvine, CA, 92617 (United States)

    2007-09-21

    Fluorescence diffuse optical tomography (FT) is an emerging molecular imaging technique that can spatially resolve both fluorophore concentration and lifetime parameters. In this study, we investigate the performance of a frequency-domain FT system for small inclusions that are embedded in a heterogeneous background. The results demonstrate that functional and structural a priori information is crucial to be able to recover both parameters with high accuracy. The functional a priori information is defined by the absorption and scattering maps at both excitation and emission wavelengths. Similarly, the boundaries of the small inclusion and different regions in the background are utilized as the structural a priori information. Without a priori information, the fluorophore concentration of a 5 mm inclusion in a 40 mm medium is recovered with 50% error, while the lifetime cannot be recovered at all. On the other hand, when both functional and structural information are available, the true lifetime can be recovered and the fluorophore concentration can be estimated only with 5% error. This study shows that a hybrid system that can acquire diffuse optical absorption tomography (DOT), FT and anatomical images in the same setting is essential to be able to recover the fluorophore concentration and lifetime accurately in vivo.

  3. Maculopatía hipotónica diagnosticada por tomografía de coherencia óptica / Hypotony maculopathy diagnosed by optical coherence tomography

    Scientific Electronic Library Online (English)

    JM, Martínez de la Casa; J, García Feijoó; A, Castillo Gómez; JM, Macías Benítez; C, Martín Valdizán; J, García Sánchez.

    2003-10-01

    Full Text Available Caso clínico: Paciente de 40 años diagnosticado de glaucoma pigmentario avanzado en su OI al que le fue realizada una trabeculectomía, presentando en el postoperatorio inmediato un descenso en la agudeza visual sin alteraciones evidentes en la exploración del fondo de ojo ni en la angiofluoresceingr [...] afía. La tomografía de coherencia óptica permitió establecer el diagnóstico de maculopatía hipotónica e instaurar un tratamiento precoz. Discusión: La maculopatía hipotónica es una de las complicaciones más temidas en el postoperatorio de la cirugía filtrante. La tomografía de coherencia óptica puede ser útil en determinados casos para confirmar el diagnóstico de forma no invasiva. Abstract in english Case report: A 40 year-old man with advanced pigmentary glaucoma in the left eye underwent trabeculectomy. In the immediate postoperative period, visual acuity decreased with no alterations noted on examination of the fundus or on angiofluoresceingraphy. Through optical coherence tomography, we were [...] able to make a diagnosis of hypotonic maculopathy and treatment was immediately started. Discussion: Hypotony maculopathy is one of the most feared complications of filtering eye surgery. In some cases, optical coherence tomography can be useful to confirm its diagnosis non invasively.

  4. High-definition optical coherence tomography imaging of melanocytic lesions : a pilot study

    DEFF Research Database (Denmark)

    Boone, Marc A L M; Norrenberg, Sarah

    2014-01-01

    High-definition optical coherence tomography (HD-OCT) is a non-invasive in vivo imaging technique with cellular resolution based on the principle of conventional optical coherence tomography. The objective of this study was to evaluate HD-OCT for its ability to identify architectural patterns and cytologic features of melanocytic lesions. All lesions were examined by one observer clinically and using dermoscopy. Cross-sectional HD-OCT images were compared with histopathology. En face HD-OCT images were compared with reflectance confocal microscopy (RCM). Twenty-six melanocytic lesions of 26 patients were imaged. Identification of architectural patterns in cross-sectional mode and cytologic features of pigmented cells in the epidermis, dermo-epidermal junction, papillary dermis, and superficial reticular dermis in the en face mode was possible by HD-OCT. HD-OCT provides morphological imaging with sufficient resolution and penetration depth to discriminate architectural patterns and cytologic features of pigmented cells in epidermis and dermis. The method appears to offer the possibility of additional three-dimensional structural information complementary to that of RCM, albeit at a slightly lower lateral resolution. The diagnostic potential of HD-OCT regarding malignant melanoma is not high enough for ruling out a diagnosis of malignant melanoma.

  5. Time reversal optical tomography locates fluorescent targets in a turbid medium

    Science.gov (United States)

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

    2013-03-01

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

  6. Current and evolving uses of optical coherence tomography in the genitourinary tract.

    Science.gov (United States)

    Gupta, Mohit; Su, Li-Ming

    2015-03-01

    Optical coherence tomography is an emerging imaging modality that provides high-resolution, real-time, cross-sectional visualization of urologic tissue with promising results. Early studies have demonstrated detailed, accurate histologic information of tissues sampled. Optical coherence tomography (OCT) has also been applied in evaluating malignancy of the bladder, prostate, and kidney. In the bladder, it can assist in the identification, biopsy, and intraoperative resection of lesions suspicious for bladder cancer. Intraoperative use of OCT during radical prostatectomy can improve visualization of the neurovascular bundle and surgical margins. Several small, ex vivo studies have also shown promising results in the ability of OCT to demonstrate histopathologic alterations to renal morphology such as in renal ischemia and malignancy. In men with non-obstructive azoospermia, OCT has also been used in improving sperm retrieval rates by assisting in the identification of tubules with isolated foci of spermatogenesis. Common limitations of OCT include limited depth of penetration and limited number of current clinical studies. PMID:25677236

  7. High-Resolution Optical Doppler Tomography for in Vitro and in Vivo Fluid Flow Dynamics

    Directory of Open Access Journals (Sweden)

    Cheng-Jen Chang

    2003-06-01

    Full Text Available Background: The objective of our research was to use a noninvasive tomographic imagingtechnique with high spatial resolution (2-15 ?m to characterize and monitorfluid flow and the microvasculature in highly scattering biological tissues atuser-specified discrete locations.Methods: The technique of optical Doppler tomography (ODT combines laserDoppler flowmetry (LDF with optical coherence tomography to obtainhigh-resolution tomographic velocity and structural images of static andmoving constituents in highly scattering biological tissues. We present ODTstructural and velocity images using in vitro turbid samples of a circular conduitinfused with a suspension of polymer microspheres. At a thin rectangularcross-section of the conduit, the Intralipid flow was measured. Bloodflow velocity was measured in vivo in the ear of rodent skin.Results: In first model, the ODT velocity images demonstrated beads near the centerof the conduit moving faster than those near the circular wall. In the secondmodel, the ODT velocity images indicated that laminar flow was fastestalong the central axis of the conduit. Blood flow in 2 small veins with diametersof 70 and 40 ?m, respectively, and an artery with diameter of 25 ?m,was clearly identified in a rodent model.Conclusion: In our preliminary in vitro and in vivo studies on turbid samples and modelvasculatures, we determined that the application of ODT to characterize andimage blood flow with high spatial resolution at discrete user-specified locationsin highly scattering biological tissues is feasible.

  8. Advanced multi-contrast Jones matrix optical coherence tomography for Doppler and polarization sensitive imaging.

    Science.gov (United States)

    Ju, Myeong Jin; Hong, Young-Joo; Makita, Shuichi; Lim, Yiheng; Kurokawa, Kazuhiro; Duan, Lian; Miura, Masahiro; Tang, Shuo; Yasuno, Yoshiaki

    2013-08-12

    An advanced version of Jones matrix optical coherence tomography (JMT) is demonstrated for Doppler and polarization sensitive imaging of the posterior eye. JMT is capable of providing localized flow tomography by Doppler detection and investigating the birefringence property of tissue through a three-dimensional (3-D) Jones matrix measurement. Owing to an incident polarization multiplexing scheme based on passive optical components, this system is stable, safe in a clinical environment, and cost effective. Since the properties of this version of JMT provide intrinsic compensation for system imperfection, the system is easy to calibrate. Compared with the previous version of JMT, this advanced JMT achieves a sufficiently long depth measurement range for clinical cases of posterior eye disease. Furthermore, a fine spectral shift compensation method based on the cross-correlation of calibration signals was devised for stabilizing the phase of OCT, which enables a high sensitivity Doppler OCT measurement. In addition, a new theory of JMT which integrates the Jones matrix measurement, Doppler measurement, and scattering measurement is presented. This theory enables a sensitivity-enhanced scattering OCT and high-sensitivity Doppler OCT. These new features enable the application of this system to clinical cases. A healthy subject and a geographic atrophy patient were measured in vivo, and simultaneous imaging of choroidal vasculature and birefringence structures are demonstrated. PMID:23938857

  9. Methods for a fusion of optical coherence tomography and stereo camera image data

    Science.gov (United States)

    Bergmeier, Jan; Kundrat, Dennis; Schoob, Andreas; Kahrs, Lüder A.; Ortmaier, Tobias

    2015-03-01

    This work investigates combination of Optical Coherence Tomography and two cameras, observing a microscopic scene. Stereo vision provides realistic images, but is limited in terms of penetration depth. Optical Coherence Tomography (OCT) enables access to subcutaneous structures, but 3D-OCT volume data do not give the surgeon a familiar view. The extension of the stereo camera setup with OCT imaging combines the benefits of both modalities. In order to provide the surgeon with a convenient integration of OCT into the vision interface, we present an automated image processing analysis of OCT and stereo camera data as well as combined imaging as augmented reality visualization. Therefore, we care about OCT image noise, perform segmentation as well as develop proper registration objects and methods. The registration between stereo camera and OCT results in a Root Mean Square error of 284 ?m as average of five measurements. The presented methods are fundamental for fusion of both imaging modalities. Augmented reality is shown as application of the results. Further developments lead to fused visualization of subcutaneous structures, as information of OCT images, into stereo vision.

  10. Sub-diffuse interstitial optical tomography to improve the safety of brain needle biopsies: a proof-of-concept study.

    Science.gov (United States)

    Goyette, Andréanne; Pichette, Julien; Tremblay, Marie-Andrée; Laurence, Audrey; Jermyn, Michael; Mok, Kelvin; Paulsen, Keith D; Roberts, David W; Petrecca, Kevin; Wilson, Brian C; Leblond, Frédéric

    2015-01-15

    The extraction of tissue samples during brain needle biopsy can cause life-threatening hemorrhage because of significant blood vessel injury during the procedure. Vessel rupture can have significant consequences for patient health, ranging from transient neurological deficits to death. Here, we present a sub-diffuse optical tomography technique that can be integrated into neurosurgical workflow to detect the presence of blood vessels. A proof-of-concept study performed on a realistic brain tissue phantom is presented and demonstrates that interstitial optical tomography (iOT) can detect several 1 mm diameter high-contrast absorbing objects located <2??mm from the needle. PMID:25679836

  11. Effects of optical beam angle on quantitative optical coherence tomography (OCT) in normal and surface degenerated bovine articular cartilage

    Energy Technology Data Exchange (ETDEWEB)

    Huang Yanping; Wang Like; Zheng Yongping [Department of Health Technology and Informatics, Hong Kong Polytechnic University (Hong Kong); Saarakkala, Simo; Toyras, Juha; Jurvelin, Jukka S, E-mail: hti.huang@polyu.edu.hk [Department of Physics and Mathematics, University of Eastern Finland, Kuopio (Finland)

    2011-01-21

    Quantitative measurement of articular cartilage using optical coherence tomography (OCT) is a potential approach for diagnosing the early degeneration of cartilage and assessing the quality of its repair. However, a non-perpendicular angle of the incident optical beam with respect to the tissue surface may cause uncertainty to the quantitative analysis, and therefore, significantly affect the reliability of measurement. This non-perpendicularity was systematically investigated in the current study using bovine articular cartilage with and without mechanical degradation. Ten fresh osteochondral disks were quantitatively measured before and after artificially induced surface degradation by mechanical grinding. The following quantitative OCT parameters were determined with a precise control of the surface inclination up to an angle of 10{sup 0} using a step of 2{sup 0}: optical reflection coefficient (ORC), variation of surface reflection (VSR) along the surface profile, optical roughness index (ORI) and optical backscattering (OBS). It was found that non-perpendicularity caused systematic changes to all of the parameters. ORC was the most sensitive and OBS the most insensitive to the inclination angle. At the optimal perpendicular angle, all parameters could detect significant changes after surface degradation (p < 0.01), except OBS (p > 0.05). Nonsignificant change of OBS after surface degradation was expected since OBS reflected properties of the internal cartilage tissue and was not affected by the superficial mechanical degradation. As a conclusion, quantitative OCT parameters are diagnostically potential for characterizing the cartilage degeneration. However, efforts through a better controlled operation or corrections based on computational compensation mechanism should be made to minimize the effects of non-perpendicularity of the incident optical beam when clinical use of quantitative OCT is considered for assessing the articular cartilage.

  12. Effects of optical beam angle on quantitative optical coherence tomography (OCT) in normal and surface degenerated bovine articular cartilage

    International Nuclear Information System (INIS)

    Quantitative measurement of articular cartilage using optical coherence tomography (OCT) is a potential approach for diagnosing the early degeneration of cartilage and assessing the quality of its repair. However, a non-perpendicular angle of the incident optical beam with respect to the tissue surface may cause uncertainty to the quantitative analysis, and therefore, significantly affect the reliability of measurement. This non-perpendicularity was systematically investigated in the current study using bovine articular cartilage with and without mechanical degradation. Ten fresh osteochondral disks were quantitatively measured before and after artificially induced surface degradation by mechanical grinding. The following quantitative OCT parameters were determined with a precise control of the surface inclination up to an angle of 100 using a step of 20: optical reflection coefficient (ORC), variation of surface reflection (VSR) along the surface profile, optical roughness index (ORI) and optical backscattering (OBS). It was found that non-perpendicularity caused systematic changes to all of the parameters. ORC was the most sensitive and OBS the most insensitive to the inclination angle. At the optimal perpendicular angle, all parameters could detect significant changes after surface degradation (p 0.05). Nonsignificant change of OBS after surface degradation was expected since OBS reflected properties of the internal caBS reflected properties of the internal cartilage tissue and was not affected by the superficial mechanical degradation. As a conclusion, quantitative OCT parameters are diagnostically potential for characterizing the cartilage degeneration. However, efforts through a better controlled operation or corrections based on computational compensation mechanism should be made to minimize the effects of non-perpendicularity of the incident optical beam when clinical use of quantitative OCT is considered for assessing the articular cartilage.

  13. Anatomic relationship of the optic nerve channel with sphenoid al sinus: a computed tomography study

    International Nuclear Information System (INIS)

    The sphenoid sinus, out of the facial sinuses, is certainly the most neglected as far as diagnosis is concerned. The surgical approach requires a detailed anatomical knowledge, considering the serious complications resulting from injuries of vital structures adjacent to this region. Aim: the objective of our research is to evaluate the anatomic relationship of the optic nerve with the sphenoid sinus making use of the computed tomography. Study design: series report. Material and method: the authors present a retrospective analysis of 203 computed tomographies of facial sinus belonging to individuals of both sexes aged 14 and over. The examinations were evaluated observing the course of the optic nerve, obtained through the degree of its projection on the wall of the sphenoid sinus. The method used was the modified classification of Delano, evaluating the absence of bone reduction (dehiscence) of the optic nerve in the sphenoid sinus. We analysed the degree of pneumatization of the sphenoid sinus, using Hammer's classification adapted by Guerrero, apart from the pneumatization of the anterior clinoidal process and pterigoid and the presence of the Onodi cell. Results: most of the patients (78.96%) presented their optic nerve with a type 1 course. Type 2 was observed in 16.83% of the patients, type 3 in 3.47% and type 4 in 0.74%. The presence of dehiscence of the optic nerve in the wall of the sphenoid sinus was evidenced in 21.29% of the cases. Related to pneumatizatio29% of the cases. Related to pneumatization, we noticed that the pre-selar type was observed in 6.44%, the post-selar type appeared in 39.11%, the selar type appeared in 54.45%, and the apneumatized type was not observed in any of the cases. The pneumatization of the anterior clinoidal process was verified in 10.64% of the cases, while the pterigoid process was apparent in 21.29% of the cases. The Onodi cell (sphenoetmoidal) was found in 7.92% of the cases. Conclusion: the presence of dehiscence of the optic nerve is related with the degree of pneumatization of the anterior clinoid and the pterigoid processes, the presence of the Onodi cell (sphenoetmoidal) and course types 2, 3 and 4 considered the relationship between the optic nerve and the sphenoid sinus. (author)

  14. Approach of trans-rectal NIR optical tomography probing for the imaging of prostate with trans-rectal ultrasound correlation

    Science.gov (United States)

    Piao, Daqing; Jiang, Zhen; Xu, Guan; Musgrove, Cameron; Bunting, Charles F.

    2008-02-01

    The trans-rectal implementation of NIR optical tomography makes it possible to assess functional status like hemoglobin concentration and oxygen saturation in prostate non-invasively. Trans-rectal NIR tomography may provide tissue-specific functional contrast that is potentially valuable for differentiation of cancerous lesions from normal tissues. Such information will help to determine if a prostate biopsy is needed or can be excluded for an otherwise ambiguous lesion. The relatively low spatial resolution due to the diffuse light detection in trans-rectal NIR tomography, however, limits the accuracy of localizing a suspicious tissue volume. Trans-rectal ultrasound (TRUS) is the clinical standard for guiding the positioning of biopsy needle owing to its resolution and convenience; nevertheless, TRUS lacks the pathognomic specificity to guide biopsy to only the suspicious lesions. The combination of trans-rectal NIR tomography with TRUS could potentially give better differentiation of cancerous tissue from normal background and to accurately localize the cancer-suspicious contrast obtained from NIR tomography. This paper will demonstrate the design and initial evaluation of a trans-rectal NIR tomography probe that can conveniently integrate with a commercial TRUS transducer. The transrectal NIR tomography obtained from this probe is concurrent with TRUS at matching sagittal imaging plane. This design provides the flexibility of simple correlation of trans-rectal NIR with TRUS, and using TRUS anatomic information as spatial prior for NIR image reconstruction.

  15. Optical coherence tomography phase measurement of transient changes in squid giant axons during activity.

    Science.gov (United States)

    Akkin, Taner; Landowne, David; Sivaprakasam, Aarthi

    2009-09-01

    Noncontact optical measurements reveal that transient changes in squid giant axons are associated with action potential propagation and altered under different environmental (i.e., temperature) and physiological (i.e., ionic concentrations) conditions. Using a spectral-domain optical coherence tomography system, which produces real-time cross-sectional images of the axon in a nerve chamber, axonal surfaces along a depth profile are monitored. Differential phase analyses show transient changes around the membrane on a millisecond timescale, and the response is coincident with the arrival of the action potential at the optical measurement area. Cooling the axon slows the electrical and optical responses and increases the magnitude of the transient signals. Increasing the NaCl concentration bathing the axon, whose diameter is decreased in the hypertonic solution, results in significantly larger transient signals during action potential propagation. While monophasic and biphasic behaviors are observed, biphasic behavior dominates the results. The initial phase detected was constant for a single location but alternated for different locations; therefore, these transient signals acquired around the membrane appear to have local characteristics. PMID:19806385

  16. Acousto-optic tomography using amplitude-modulated focused ultrasound and a near-IR laser

    International Nuclear Information System (INIS)

    A novel tomographic method that can be applied in strongly scattering optical media is proposed. 1-MHz focused ultrasound is used to tag the scattering photons in the biological tissue; it carries a 10-KHz sinusoidal wave to act as a detection wave through amplitude-modulation (AM). The scattering photons that come from the focused zone carry the modulated information. Their optoelectronic signal is demodulated by real-time FFT. By detecting and discriminating ultrasound-modulated information carried by scattered photons, the optical tomographic images of the media simulating biological tissue and of a buried object are reconstructed by the AM spectral intensity. This ultrasound-tagged optical tomography can be applied to tissue structures with different optical parameters. For the first time, by using this method, we obtained the tomographic image of a 5 mm-wide soft rubber cube buried in a biological tissue-simulating media with a detecting depth of 30 mm. (laser applications and other topics in quantum electronics)

  17. Iterative reconstruction scheme for optical tomography based on the equation of radiative transfer.

    Science.gov (United States)

    Klose, A D; Hielscher, A H

    1999-08-01

    We report on the development of an iterative image reconstruction scheme for optical tomography that is based on the equation of radiative transfer. Unlike the commonly applied diffusion approximation, the equation of radiative transfer accurately describes the photon propagation in turbid media without any limiting assumptions regarding the optical properties. The reconstruction scheme consists of three major parts: (1) a forward model that predicts the detector readings based on solutions of the time-independent radiative transfer equation, (2) an objective function that provides a measure of the differences between the detected and the predicted data, and (3) an updating scheme that uses the gradient of the objective function to perform a line minimization to get new guesses of the optical properties. The gradient is obtained by employing an adjoint differentiation scheme, which makes use of the structure of the finite-difference discrete-ordinate formulation of the transport forward model. Based on the new guess of the optical properties a new forward calculation is performed to get new detector predictions. The reconstruction process is completed when the minimum of the objective function is found within a defined error. To illustrate the performance of the code we present initial reconstruction results based on simulated data. PMID:10501069

  18. Optical coherence tomography signal analysis: LIDAR like equation and inverse methods

    International Nuclear Information System (INIS)

    Optical Coherence Tomography (OCT) is based on the media backscattering properties in order to obtain tomographic images. In a similar way, LIDAR (Light Detection and Range) technique uses these properties to determine atmospheric characteristics, specially the signal extinction coefficient. Exploring this similarity allowed the application of signal inversion methods to the OCT images, allowing to construct images based in the extinction coefficient, original result until now. The goal of this work was to study, propose, develop and implement algorithms based on OCT signal inversion methodologies with the aim of determine the extinction coefficient as a function of depth. Three inversion methods were used and implemented in LABViewR: slope, boundary point and optical depth. Associated errors were studied and real samples (homogeneous and stratified) were used for two and three dimension analysis. The extinction coefficient images obtained from the optical depth method were capable to differentiate air from the sample. The images were studied applying PCA and cluster analysis that established the methodology strength in determining the sample's extinction coefficient value. Moreover, the optical depth methodology was applied to study the hypothesis that there is some correlation between signal extinction coefficient and the enamel teeth demineralization during a cariogenic process. By applying this methodology, it was possible to observe the variation of the extinction coefficient as depth function and its correlation with microhardness variation, showing that in deeper layers its values tends to a healthy tooth values, behaving as the same way that the microhardness. (author)

  19. Morphological and functional changes in spectral domain optical coherence tomography and microperimetry in macular microhole variants: Spectral domain optical coherence tomography and microperimetry correlation

    Directory of Open Access Journals (Sweden)

    Laxmi Gella

    2012-01-01

    Full Text Available Purpose: To evaluate the relationship between the morphology and retinal function of macular microhole (MMH variants. Materials and Methods: We evaluated 12 eyes of 11 patients with defects in the IS/OS junction of photoreceptor layer with SD-OCT. All patients underwent comprehensive ophthalmic examination including spectral domain optical coherence tomography (SD-OCT and microperimetry. Results: The mean logMAR visual acuity in the affected eye was 0.15 ± 0.17 (range 0.00-0.5. Mean horizontal diameter of the MMH was 163 ± 99 ?m; the mean retinal sensitivity in the area corresponding to the MMH was 13.79 ± 4.6 dB. Negative correlation was found between the MMH diameter and the retinal sensitivity (r = -0.65, p0 = 0.02. Three morphological patterns of MMH variants were recognized on SD-OCT, which did not differ in retinal sensitivities. Conclusion: We described and classified the MMH variants and made an assessment on the physiological functions using microperimeter.

  20. High-resolution imaging of biological tissue with full-field optical coherence tomography

    Science.gov (United States)

    Zhu, Yue; Gao, Wanrong

    2015-03-01

    A new full-field optical coherence tomography system with high-resolution has been developed for imaging of cells and tissues. Compared with other FF-OCT (Full-field optical coherence tomography, FF-OCT) systems illuminated with optical fiber bundle, the improved Köhler illumination arrangement with a halogen lamp was used in the proposed FF-OCT system. High numerical aperture microscopic objectives were used for imaging and a piezoelectric ceramic transducer (PZT) was used for phase-shifting. En-face tomographic images can be obtained by applying the five-step phase-shifting algorithm to a series of interferometric images which are recorded by a smart camera. Three-dimensional images can be generated from these tomographic images. Imaging of the chip of Intel Pentium 4 processor demonstrated the ultrahigh resolution of the system (lateral resolution is 0.8?m ), which approaches the theoretical resolution 0.7 ?m× 0.5 ?m (lateral × axial). En-face images of cells of onion show an excellent performance of the system in generating en-face images of biological tissues. Then, unstained pig stomach was imaged as a tissue and gastric pits could be easily recognized using FF-OCT system. Our study provides evidence for the potential ability of FFOCT in identifying gastric pits from pig stomach tissue. Finally, label-free and unstained ex vivo human liver tissues from both normal and tumor were imaged with this FFOCT system. The results show that the setup has the potential for medical diagnosis applications such liver cancer diagnosis.

  1. Hemifield pattern electroretinogram in ocular hypertension: comparison with frequency doubling technology and optical coherence tomography to detect early optic neuropathy

    Directory of Open Access Journals (Sweden)

    Finzi A

    2014-09-01

    Full Text Available Alessandro Finzi, Ernesto Strobbe, Filippo Tassi, Michela Fresina, Mauro Cellini Department of Specialized, Diagnostic and Experimental Medicine, Ophthalmology Service, University of Bologna, Bologna, Italy Background: To assess the sensitivity and specificity of hemifield pattern electroretinogram (HF-PERG for detecting early retinal ganglion cell (RGC damage in ocular hypertensive (OH patients.Methods: Fifty-two OH patients (mean age 56±9.6 years with an intraocular pressure (IOP >21 mmHg were assessed. All subjects underwent HF-PERG, optical coherence tomography (OCT, and frequency doubling technology (FDT visual field.Results: OH patients showed a significant increase of peak-time of the N95 (P=0.027 compared to controls. The amplitude of the N95 of the lower and upper HF-PERG showed significant differences (P=0.037 and P=0.023, respectively between the two groups. A significant intraocular (P=0.006 and interocular (P=0.018 asymmetry of N95 amplitude was found. Receiver operating characteristic (ROC curve analysis revealed a sensitivity of 93% for the N95 of the lower HF-PERG, whereas full-field pattern electroretinogram (PERG N95 peak-time had a sensitivity of 88%. In OH patients, we found a thinning of OCT - retinal nerve fiber layer (RNFL, especially in the superior and inferior quadrant, although not statistically significant, and a significantly higher FDT pattern standard deviation (FDT-PSD; P=0.001. In the OCT-RNFL inferior quadrant, a sensitivity of 82% was recorded. Finally, the sensitivity of the FDT-PSD was 92%.Conclusion: Our study shows that HF-PERG is a very sensitive test for detecting early damage of the RGC. Keywords: ocular hypertension, hemifield pattern electroretinogram, optical coherence tomography, frequency doubling technology 

  2. Optical coherence tomography detection of shear wave propagation in inhomogeneous tissue equivalent phantoms and ex-vivo carotid artery samples

    OpenAIRE

    Razani, Marjan; Luk, Timothy W. H.; Mariampillai, Adrian; Siegler, Peter; Kiehl, Tim-Rasmus; Kolios, Michael C; Yang, Victor X. D.

    2014-01-01

    In this work, we explored the potential of measuring shear wave propagation using optical coherence elastography (OCE) in an inhomogeneous phantom and carotid artery samples based on a swept-source optical coherence tomography (OCT) system. Shear waves were generated using a piezoelectric transducer transmitting sine-wave bursts of 400 ?s duration, applying acoustic radiation force (ARF) to inhomogeneous phantoms and carotid artery samples, synchronized with a swept-source OCT (SS-OCT) imagi...

  3. Measurement of a multi-layered tear film phantom using optical coherence tomography and statistical decision theory

    OpenAIRE

    Huang, Jinxin; Yuan, Qun; Zhang, Buyun; Xu, Ke; Tankam, Patrice; Clarkson, Eric; Kupinski, Matthew A.; Hindman, Holly B.; Aquavella, James V.; Suleski, Thomas J.; Rolland, Jannick P.

    2014-01-01

    To extend our understanding of tear film dynamics for the management of dry eye disease, we propose a method to optically sense the tear film and estimate simultaneously the thicknesses of the lipid and aqueous layers. The proposed method, SDT-OCT, combines ultra-high axial resolution optical coherence tomography (OCT) and a robust estimator based on statistical decision theory (SDT) to achieve thickness measurements at the nanometer scale. Unlike conventional Fourier-domain OCT where peak de...

  4. Design & development of a galvanometer inspired dual beam optical coherence tomography system for flow velocity quantification of the microvasculature

    OpenAIRE

    Mcelligott-daly, Susan; Jonathan, E.; Leahy, Martin J.

    2011-01-01

    This paper reports initial experimentation of a dual beam flow velocity estimation setup based on optical coherence tomography (OCT) for biomedical applications. The proposed work incorporates a low cost switching mechanism (rotating galvanometer mirror) for optical signal discrimination between adjacent fiber channels enabling quasisimultaneous multiple specimen scanning. A cascaded interferometric design is used with two sample output arms orientated in parallel to eachother. A cross-cor...

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

    OpenAIRE

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

    2012-01-01

    We describe the validation of an anatomical brain atlas approach to the analysis of diffuse optical tomography (DOT). Using MRI data from 32 subjects, we compare the diffuse optical images of simulated cortical activation reconstructed using a registered atlas with those obtained using a subject’s true anatomy. The error in localization of the simulated cortical activations when using a registered atlas is due to a combination of imperfect registration, anatomical differences between atlas ...

  6. Apices of maxillary premolars observed by swept source optical coherence tomography

    Science.gov (United States)

    Ebihara, Arata; Iino, Yoshiko; Yoshioka, Toshihiko; Hanada, Takahiro; Sunakawa, Mitsuhiro; Sumi, Yasunori; Suda, Hideaki

    2015-02-01

    Apicoectomy is performed for the management of apical periodontitis when orthograde root canal treatment is not possible or is ineffective. Prior to the surgery, cone beam computed tomography (CBCT) examination is often performed to evaluate the lesion and the adjacent tissues. During the surgical procedure, the root apex is resected and the resected surface is usually observed under dental operating microscope (DOM). However, it is difficult to evaluate the details and the subsurface structure of the root using CBCT and DOM. A new diagnostic system, swept source optical coherence tomography (SS-OCT), has been developed to observe the subsurface anatomical structure. The aim of this study was to observe resected apical root canals of human maxillary premolars using SS-OCT and compare the findings with those observed using CBCT and DOM. Six extracted human maxillary premolars were used. After microfocus computed tomography (Micro CT; for gold standard) and CBCT scanning of the root, 1 mm of the apex was cut perpendicular to the long axis of the tooth. Each resected surface was treated with EDTA, irrigated with saline solution, and stained with methylene blue dye. The resected surface was observed with DOM and SS-OCT. This sequence was repeated three times. The number of root canals was counted and statistically evaluated. There was no significant difference in the accuracy of detecting root canals among CBCT, DOM and SS-OCT (p > 0.05, Wilcoxon test). Because SS-OCT can be used in real time during surgery, it would be a useful tool for observing resected apical root canals.

  7. En face optical coherence tomography investigation of interface fiber posts/adhesive cement/root canal wall

    Science.gov (United States)

    Negru?iu, Meda; Sinescu, Cosmin; Topala, Florin; Rominu, Mihai; Markovic, Dubravka; Pop, Daniela; Hughes, Michael; Bradu, Adrian; Dobre, George; Podoleanu, Adrian G.

    2009-07-01

    This study analyzes the adaptation and gap width between fiber posts, adhesive luting cement and root canal wall using optical coherence tomography. The results prove the importance of assessing the quality of the interface after each process of fiber post luting.

  8. Microvascular anastomosis in rodent model evaluated by Fourier domain Doppler optical coherence tomography

    Science.gov (United States)

    Huang, Yong; Tong, Dedi; Zhu, Shan; Wu, Lehao; Ibrahim, Zuhaib; Lee, WP Andrew; Brandacher, Gerald; Kang, Jin U.

    2014-03-01

    Vascular and microvascular anastomosis are critical components of reconstructive microsurgery, vascular surgery and transplant surgery. Imaging modality that provides immediate, real-time in-depth view and 3D structure and flow information of the surgical site can be a great valuable tool for the surgeon to evaluate surgical outcome following both conventional and innovative anastomosis techniques, thus potentially increase the surgical success rate. Microvascular anastomosis for vessels with outer diameter smaller than 1.0 mm is extremely challenging and effective evaluation of the outcome is very difficult if not impossible using computed tomography (CT) angiograms, magnetic resonance (MR) angiograms and ultrasound Doppler. Optical coherence tomography (OCT) is a non-invasive high-resolution (micron level), high-speed, 3D imaging modality that has been adopted widely in biomedical and clinical applications. Phaseresolved Doppler OCT that explores the phase information of OCT signals has been shown to be capable of characterizing dynamic blood flow clinically. In this work, we explore the capability of Fourier domain Doppler OCT as an evaluation tool to detect commonly encountered post-operative complications that will cause surgical failure and to confirm positive result with surgeon's observation. Both suture and cuff based techniques were evaluated on the femoral artery and vein in the rodent model.

  9. 3D optical coherence tomography image registration for guiding cochlear implant insertion

    Science.gov (United States)

    Cheon, Gyeong-Woo; Jeong, Hyun-Woo; Chalasani, Preetham; Chien, Wade W.; Iordachita, Iulian; Taylor, Russell; Niparko, John; Kang, Jin U.

    2014-03-01

    In cochlear implant surgery, an electrode array is inserted into the cochlear canal to restore hearing to a person who is profoundly deaf or significantly hearing impaired. One critical part of the procedure is the insertion of the electrode array, which looks like a thin wire, into the cochlear canal. Although X-ray or computed tomography (CT) could be used as a reference to evaluate the pathway of the whole electrode array, there is no way to depict the intra-cochlear canal and basal turn intra-operatively to help guide insertion of the electrode array. Optical coherent tomography (OCT) is a highly effective way of visualizing internal structures of cochlea. Swept source OCT (SSOCT) having center wavelength of 1.3 micron and 2D Galvonometer mirrors was used to achieve 7-mm depth 3-D imaging. Graphics processing unit (GPU), OpenGL, C++ and C# were integrated for real-time volumetric rendering simultaneously. The 3D volume images taken by the OCT system were assembled and registered which could be used to guide a cochlear implant. We performed a feasibility study using both dry and wet temporal bones and the result is presented.

  10. Design of a rotational ultrasound guided diffuse optical tomography system for whole breast imaging

    Science.gov (United States)

    Deng, Zixin; Lin, Yuting; Ikemura, Kenji; Tseng, Michael; Chan, Yu-Wen; Gulsen, Gultekin

    2013-03-01

    This study focuses on a multimodal imaging technique that integrates both structural and functional information using a priori ultrasound (US) information to assist near-infrared (NIR) diffuse optical tomography (DOT). Up to date, handheld systems that integrates DOT and US have been demonstrated. Our system is designed to be fully-automated and non-contact. Our aim is to build an interface, in which the optical source and detector fibers will rotate around the breast together with the US transducer. However, in this study we built a prototype system, which rotated the phantom and kept the transducers stationary for simplicity. Simulation and experimental studies were performed using a variety of sourcedetector configurations. The reconstruction results were compared with and without US a priori information. To collect the a priori US information, the multi-modality agar phantom was rotated 360° using a computer controlled rotational stage. The multi-modality phantom had an inclusion that had both optical absorption and US contrast. 360 US images were collected in 1° increments covering the entire phantom volume. The DOT data was also collected while the phantom is rotated with particular source-detector configurations. These results have shown that when the detectors were ? /8 apart, and the phantom is rotating at ? /16 increments with a total of 32 views provide the optimum image reconstruction. As expected, US a priori information further improved the quantification accuracy.

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

    Science.gov (United States)

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

    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 images of the lesion by using dynamic contrast enhanced DOT (DCE-DOT). This produces a relative absorption map that consists of subtracting a reconstructed baseline image from reconstructed images in which optical contrast is included. In this study, we investigated and compared different reconstruction methods and analysis approaches for regular endogenous DOT and DCE-DOT with and without MR anatomical a priori information for arbitrarily-shaped objects. Our phantom and animal studies have shown that superior image quality and higher accuracy can be achieved using DCE-DOT together with MR structural a priori information. Hence, implementation of a combined MRI-DOT system to image ICG enhancement can potentially be a promising tool for breast cancer imaging. PMID:21811492

  12. Handheld photoacoustic tomography probe built using optical-fiber parallel acoustic delay lines

    Science.gov (United States)

    Cho, Young; Chang, Cheng-Chung; Yu, Jaesok; Jeon, Mansik; Kim, Chulhong; Wang, Lihong V.; Zou, Jun

    2014-08-01

    The development of the first miniaturized parallel acoustic delay line (PADL) probe for handheld photoacoustic tomography (PAT) is reported. Using fused-silica optical fibers with low acoustic attenuation, we constructed two arrays of eight PADLs. Precision laser micromachining was conducted to produce robust and accurate mechanical support and alignment structures for the PADLs, with minimal acoustic distortion and interchannel coupling. The 16 optical-fiber PADLs, each with a different time delay, were arranged to form one input port and two output ports. A handheld PADL probe was constructed using two single-element transducers and two data acquisition channels (equal to a channel reduction ratio of 8?1). Photoacoustic (PA) images of a black-ink target embedded in an optically scattering phantom were successfully acquired. After traveling through the PADLs, the eight channels of differently time-delayed PA signals reached each single-element ultrasonic transducer in a designated nonoverlapping time series, allowing clear signal separation for PA image reconstruction. Our results show that the PADL technique and the handheld probe can potentially enable real-time PAT, while significantly reducing the complexity and cost of the ultrasound receiver system.

  13. Optical coherence tomography imaging and fluorescence spectroscopy of a novel rat model of ovarian cancer

    Science.gov (United States)

    Kanter, Elizabeth; Walker, Ross; Marion, Sam; Hoyer, Patricia; Barton, Jennifer K.

    2005-08-01

    Ovarian cancer is relatively rare but is the fifth leading cause of death from cancer in women. Little is known about the precursors and early stages of ovarian cancer partially due to the lack of a realistic animal model. A cohesive model that incorporates ovarian cancer induction into a menopausal rodent would be well suited for comprehensive studies of ovarian cancer, and non-destructive imaging would allow carcinogenesis to be followed. Optical Coherence Tomography (OCT) and Light-Induced Fluorescence (LIF) are minimally invasive optical modalities that allow both structural and biochemical changes to be noted. Rat ovaries were exposed to 4-vinylcyclohexene diepoxide (VCD) for 20 days in order to destroy the primordial follicles. Sutures coated with 7,12-dimethylbenz(a)anthracene (DMBA) were implanted in the right ovary, in order to produce epithelial based ovarian cancers. Rats were sacrificed at 1, 3, and 5 months and ovaries were harvested and imaged with a combined OCT/LIF system. Histology was preformed on the harvested ovaries and any pathology determined. OCT was able to visualize follicle loss and DMBA-induced abnormalities. LIF spectra were also different between cycling, follicle deplete, and DMBA-exposed ovaries. Overall this pilot study demonstrated the feasibility of both the animal model and optical imaging.

  14. The impact of multifocal intraocular lens in retinal imaging with optical coherence tomography.

    Science.gov (United States)

    Dias-Santos, Arnaldo; Costa, Lívio; Lemos, Vanessa; Anjos, Rita; Vicente, André; Ferreira, Joana; Cunha, João Paulo

    2014-11-01

    Multifocal intraocular lenses (MF IOLs) have concentric optical zones with different dioptric power, enabling patients to have good visual acuity at multiple focal points. However, several optical limitations have been attributed to this particular design. The purpose of this study is to access the effect of MF IOLs design on the accuracy of retinal optical coherence tomography (OCT). Cross-sectional study conducted at the Refractive Surgery Department of Central Lisbon Hospital Center. Twenty-three eyes of 15 patients with a diffractive MF IOL and 27 eyes of 15 patients with an aspheric monofocal IOL were included in this study. All patients underwent OCT macular scans using Heidelberg Spectralis(®). Macular thickness and volume values and image quality (Q factor) were compared between the two groups. There were no statistically significant differences between both groups regarding macular thickness or volume measurements. Retinal OCT image quality was significantly lower in the MF IOL group (p IOLs are associated with a significant decrease in OCT image quality. However, this fact does not seem to compromise the accuracy of spectral domain OCT retinal measurements. PMID:25381578

  15. Comparison of optical detection system, PVDF detection system, and PVDF needle hydrophone for optoacoustic tomography

    Science.gov (United States)

    Abolhassani, M. D.; Hejazi, M.; Ahmadian, A.; Amjadi, A.

    2005-10-01

    Optoacoustic tomography (PAT) is a two-dimensional medical imaging method that has the advantage of optical contrast and resolution of ultrasonic waves. The detection systems with a high sensitivity can be used for detecting small tumors, located deeply in human tissues, such as the breast. In this study, the sensitivity of existing ultrasonic detection systems has been compared experimentally with that by using thermoelastic waves as a broadband ultrasonic source. For the comparison, an optical stress transducer (OST), a polyvinylidene difluoride (PVDF) sheet and a calibrated PVDF needle hydrophone were used. To ensure all of the detection systems interrogated by the same ultrasonic field, a small optical instrument that fixed the generating laser head was constructed. The sensitivity was evaluated by measuring signal-to-noise ratios (SNRs) and noise equivalent pressures (NEPs). The PVDF system, with a 4-kPa NEP has a 22 dB better performance than the OST. The OST showed nearly the same sensitivity as the hydrophone for detecting ultrasound waves at a 1-cm distance in water. PVDF detection system provides a useful tool for imaging of soft tissues because of its high sensitivity and broad detection range.

  16. Use of optical coherence tomography in delineating airways microstructure: comparison of OCT images to histopathological sections

    International Nuclear Information System (INIS)

    An ideal diagnostic system for the human airways should be able to detect and define early development of premalignant pathological lesions, to facilitate optimal curative treatment and prevent irreversible and/or invasive lung disease. There is great need for exploration of safe, repeatable imaging techniques which can run at real-time and with high spatial resolution. In this study, optical coherence tomography (OCT) was utilized to acquire cross-sectional images of upper and lower airways using fresh pig lung resections as a model system. Obtained OCT images were compared with parallel tissue characterization by conventional histological analysis. Our objective was to determine whether OCT differentiates the composite structural layers and inherent anatomical variations along different airway locations. The data show that OCT can clearly display the multilayered structure of the airways. The subtle architectural differences in three separate anatomical locations including trachea, main bronchus and tertiary bronchus were clearly delineated. Images of the appropriate anatomical profiles, with depth of up to 2 mm and 10 ?m spatial resolution were obtained by our current OCT system, which was sufficient for recognition of the epithelium, subepithelial tissues and cartilage. In addition, the relative thickness of individual structural components was accurately reflected and comparable to histological sections. These data support OCT as a highly feasible, optical biopst OCT as a highly feasible, optical biopsy tool, which merits further exploration for early diagnosis of human airway epithelial pathology

  17. Large-volume optical coherence tomography with real-time correction of geometric distortion artifacts

    CERN Document Server

    Van der Jeught, Sam; 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 the proposed 3D recalibration algorithm on the graphics card of a standard computer, this feature can be applied in real-time. We validate the accuracy of the technique using OCT measurements of a highly curved object within a large imaging volume of 12.35 x 10.13 x 2.36 mm^3. The resulting 3D object shape measurements are compared against high-resolution and aberration-free optical profilometry measurements. Maintaining an optical resolution of <10 micron within the sample, both axially and transversally, we realized a real-time, high-re...

  18. Single-resolution and multiresolution extended-Kalman-filter-based reconstruction approaches to optical refraction tomography.

    Science.gov (United States)

    Naik, Naren; Vasu, R M; Ananthasayanam, M R

    2010-02-20

    The problem of reconstruction of a refractive-index distribution (RID) in optical refraction tomography (ORT) with optical path-length difference (OPD) data is solved using two adaptive-estimation-based extended-Kalman-filter (EKF) approaches. First, a basic single-resolution EKF (SR-EKF) is applied to a state variable model describing the tomographic process, to estimate the RID of an optically transparent refracting object from noisy OPD data. The initialization of the biases and covariances corresponding to the state and measurement noise is discussed. The state and measurement noise biases and covariances are adaptively estimated. An EKF is then applied to the wavelet-transformed state variable model to yield a wavelet-based multiresolution EKF (MR-EKF) solution approach. To numerically validate the adaptive EKF approaches, we evaluate them with benchmark studies of standard stationary cases, where comparative results with commonly used efficient deterministic approaches can be obtained. Detailed reconstruction studies for the SR-EKF and two versions of the MR-EKF (with Haar and Daubechies-4 wavelets) compare well with those obtained from a typically used variant of the (deterministic) algebraic reconstruction technique, the average correction per projection method, thus establishing the capability of the EKF for ORT. To the best of our knowledge, the present work contains unique reconstruction studies encompassing the use of EKF for ORT in single-resolution and multiresolution formulations, and also in the use of adaptive estimation of the EKF's noise covariances. PMID:20174167

  19. Optical coherence tomography: a non-invasive technique applied to conservation of paintings

    Science.gov (United States)

    Liang, Haida; Gomez Cid, Marta; Cucu, Radu; Dobre, George; Kudimov, Boris; Pedro, Justin; Saunders, David; Cupitt, John; Podoleanu, Adrian

    2005-06-01

    It is current practice to take tiny samples from a painting to mount and examine in cross-section under a microscope. However, since conservation practice and ethics limit sampling to a minimum and to areas along cracks and edges of paintings, which are often unrepresentative of the whole painting, results from such analyses cannot be taken as representative of a painting as a whole. Recently in a preliminary study, we have demonstrated that near-infrared Optical Coherence Tomography (OCT) can be used directly on paintings to examine the cross-section of paint and varnish layers without contact and the need to take samples. OCT is an optical interferometric technique developed for in vivo imaging of the eye and biological tissues; it is essentially a scanning Michelson's interferometer with a "broad-band" source that has the spatial coherence of a laser. The low temporal coherence and high spatial concentration of the source are the keys to high depth resolution and high sensitivity 3D imaging. The technique is non-invasive and non-contact with a typical working distance of 2 cm. This non-invasive technique enables cross-sections to be examined anywhere on a painting. In this paper, we will report new results on applying near-infrared en-face OCT to paintings conservation and extend the application to the examination of underdrawings, drying processes, and quantitative measurements of optical properties of paint and varnish layers.

  20. Dynamic contrast-enhanced diffuse optical tomography (DCE-DOT): experimental validation with a dynamic phantom

    International Nuclear Information System (INIS)

    Dynamic contrast-enhanced diffuse optical tomography (DCE-DOT) can provide spatially resolved enhancement kinetics of an optical contrast agent. We undertook a systematic phantom study to evaluate the effects of the geometrical parameters such as the depth and size of the inclusion as well as the optical parameters of the background on the recovered enhancement kinetics of the most commonly used optical contrast agent, indocyanine green (ICG). For this purpose a computer-controlled dynamic phantom was constructed. An ICG-intralipid-water mixture was circulated through the inclusions while the DCE-DOT measurements were acquired with a temporal resolution of 16 s. The same dynamic study was repeated using inclusions of different sizes located at different depths. In addition to this, the effect of non-scattering regions was investigated by placing a second inclusion filled with water in the background. The phantom studies confirmed that although the peak enhancement varied substantially for each case, the recovered injection and dilution rates obtained from the percentage enhancement maps agreed within 15% independent of not only the depth and the size of the inclusion but also the presence of a non-scattering region in the background. Although no internal structural information was used in these phantom studies, it may be necessary to use it for small objects buried deep in tissue. However, the different contrast mechanisms of optical and other imaging modalities as weoptical and other imaging modalities as well as imperfect co-registration between both modalities may lead to potential errors in the structural a priori. Therefore, the effect of erroneous selection of structural priors was investigated as the final step. Again, the injection and dilution rates obtained from the percentage enhancement maps were also immune to the systematic errors introduced by erroneous selection of the structural priors, e.g. choosing the diameter of the inclusion 20% smaller increased the peak enhancement 60% but changed the injection and dilution rates only less than 10%.

  1. Dynamic contrast-enhanced diffuse optical tomography (DCE-DOT): experimental validation with a dynamic phantom

    Energy Technology Data Exchange (ETDEWEB)

    Unlu, Mehmet Burcin; Lin Yuting; Gulsen, Gultekin [Tu and Yuen Center for Functional Onco Imaging, University of California, Irvine, CA 92617 (United States)], E-mail: ggulsen@uci.edu

    2009-11-07

    Dynamic contrast-enhanced diffuse optical tomography (DCE-DOT) can provide spatially resolved enhancement kinetics of an optical contrast agent. We undertook a systematic phantom study to evaluate the effects of the geometrical parameters such as the depth and size of the inclusion as well as the optical parameters of the background on the recovered enhancement kinetics of the most commonly used optical contrast agent, indocyanine green (ICG). For this purpose a computer-controlled dynamic phantom was constructed. An ICG-intralipid-water mixture was circulated through the inclusions while the DCE-DOT measurements were acquired with a temporal resolution of 16 s. The same dynamic study was repeated using inclusions of different sizes located at different depths. In addition to this, the effect of non-scattering regions was investigated by placing a second inclusion filled with water in the background. The phantom studies confirmed that although the peak enhancement varied substantially for each case, the recovered injection and dilution rates obtained from the percentage enhancement maps agreed within 15% independent of not only the depth and the size of the inclusion but also the presence of a non-scattering region in the background. Although no internal structural information was used in these phantom studies, it may be necessary to use it for small objects buried deep in tissue. However, the different contrast mechanisms of optical and other imaging modalities as well as imperfect co-registration between both modalities may lead to potential errors in the structural a priori. Therefore, the effect of erroneous selection of structural priors was investigated as the final step. Again, the injection and dilution rates obtained from the percentage enhancement maps were also immune to the systematic errors introduced by erroneous selection of the structural priors, e.g. choosing the diameter of the inclusion 20% smaller increased the peak enhancement 60% but changed the injection and dilution rates only less than 10%.

  2. Dynamic contrast-enhanced diffuse optical tomography (DCE-DOT): experimental validation with a dynamic phantom

    Science.gov (United States)

    Burcin Unlu, Mehmet; Lin, Yuting; Gulsen, Gultekin

    2009-11-01

    Dynamic contrast-enhanced diffuse optical tomography (DCE-DOT) can provide spatially resolved enhancement kinetics of an optical contrast agent. We undertook a systematic phantom study to evaluate the effects of the geometrical parameters such as the depth and size of the inclusion as well as the optical parameters of the background on the recovered enhancement kinetics of the most commonly used optical contrast agent, indocyanine green (ICG). For this purpose a computer-controlled dynamic phantom was constructed. An ICG-intralipid-water mixture was circulated through the inclusions while the DCE-DOT measurements were acquired with a temporal resolution of 16 s. The same dynamic study was repeated using inclusions of different sizes located at different depths. In addition to this, the effect of non-scattering regions was investigated by placing a second inclusion filled with water in the background. The phantom studies confirmed that although the peak enhancement varied substantially for each case, the recovered injection and dilution rates obtained from the percentage enhancement maps agreed within 15% independent of not only the depth and the size of the inclusion but also the presence of a non-scattering region in the background. Although no internal structural information was used in these phantom studies, it may be necessary to use it for small objects buried deep in tissue. However, the different contrast mechanisms of optical and other imaging modalities as well as imperfect co-registration between both modalities may lead to potential errors in the structural a priori. Therefore, the effect of erroneous selection of structural priors was investigated as the final step. Again, the injection and dilution rates obtained from the percentage enhancement maps were also immune to the systematic errors introduced by erroneous selection of the structural priors, e.g. choosing the diameter of the inclusion 20% smaller increased the peak enhancement 60% but changed the injection and dilution rates only less than 10%.

  3. Adaptive optics optical coherence tomography at 120,000 depth scans/s for non-invasive cellular phenotyping of the living human retina

    OpenAIRE

    Torti, Cristiano; Považay, Boris; Hofer, Bernd; Unterhuber, Angelika; Carroll, Joseph; Ahnelt, Peter Kurt; Drexler, Wolfgang

    2009-01-01

    This paper presents a successful combination of ultra-high speed (120,000 depth scans/s), ultra-high resolution optical coherence tomography with adaptive optics and an achromatizing lens for compensation of monochromatic and longitudinal chromatic ocular aberrations, respectively, allowing for non-invasive volumetric imaging in normal and pathologic human retinas at cellular resolution. The capability of this imaging system is demonstrated here through preliminary studies by probing cellular...

  4. Optical coherence tomography in a patient with chloroquine-induced maculopathy

    Directory of Open Access Journals (Sweden)

    Korah Sanita

    2008-01-01

    Full Text Available We herein report the optical coherence tomography (OCT findings in a case of chloroquine-induced macular toxicity, which to our knowledge, has so far not been reported. A 53-year-old lady on chloroquine for treatment of rheumatoid arthritis developed decrease in vision 36 months after initiation of the treatment. Clinical examination revealed evidence of retinal pigment epithelial (RPE disturbances. Humphrey field analyzer (HFA, fundus fluorescein angiography (FFA and OCT for retinal thickness and volume measurements at the parafoveal region were done. The HFA revealed bilateral superior paracentral scotomas, FFA demonstrated RPE loss and OCT revealed anatomical evidence of loss of ganglion cell layers, causing marked thinning of the macula and parafoveal region. Parafoveal retinal thickness and volume measurements may be early evidence of chloroquine toxicity, and OCT measurements as a part of chloroquine toxicity screening may be useful in early detection of chloroquine maculopathy.

  5. Histogram flow mapping with optical coherence tomography for in vivo skin angiography of hereditary hemorrhagic telangiectasia.

    Science.gov (United States)

    Cheng, Kyle H Y; Mariampillai, Adrian; Lee, Kenneth K C; Vuong, Barry; Luk, Timothy W H; Ramjist, Joel; Curtis, Anne; Jakubovic, Henry; Kertes, Peter; Letarte, Michelle; Faughnan, Marie E; Yang, Victor X D

    2014-08-01

    Speckle statistics of flowing scatterers have been well documented in the literature. Speckle variance optical coherence tomography exploits the large variance values of intensity changes in time caused mainly by the random backscattering of light resulting from translational activity of red blood cells to map out the microvascular networks. A method to map out the microvasculature malformation of skin based on the time-domain histograms of individual pixels is presented with results obtained from both normal skin and skin containing vascular malformation. Results demonstrated that this method can potentially map out deeper blood vessels and enhance the visualization of microvasculature in low signal regions, while being resistant against motion (e.g., patient tremor or internal reflex movements). The overall results are manifested as more uniform en face projection maps of microvessels. Potential applications include clinical imaging of skin vascular abnormalities and wide-field skin angiography for the study of complex vascular networks. PMID:25140883

  6. Identifying glaucoma with multi-fractal features from optical coherence tomography (OCT)

    Science.gov (United States)

    Gunvant, P.; Kim, P. Y.; Iftekharuddin, K. M.; Essock, E. A.

    2011-03-01

    We propose a novel technique that exploits multi-fractal features for classifying glaucoma from ocular normal patients using retinal nerve fiber layer (RNFL) thickness measurement data. We apply a box-counting (BC) method, which utilizes pseudo 2D images from 1D RNFL data, and a multi-fractional Brownian motion (mBm) method, which incorporates both fractal and wavelet analyses, to analyze optical coherence tomography (OCT) data from 136 study participants (63 with glaucoma and 73 ocular normal patients). For statistical performance comparison, we compute the sensitivity, specificity and area under receiver operating curve (AUROC). The AUROCs in identifying glaucoma from ocular normal patients were 0.81 (BC), 0.87 (mBm), and 0.89 (BC+mBm), respectively.

  7. [Optical Coherence Tomography (OCT)--a new diagnostic tool in psychiatry?].

    Science.gov (United States)

    Schönfeldt-Lecuona, C; Schmidt, A; Pinkhardt, E H; Lauda, F; Connemann, B J; Freudenmann, R W; Gahr, M

    2014-10-01

    Optical coherence tomography (OCT) is a non-invasive, contact-less imaging method which provides an "in vivo" representation of the retina. It allows the quantitative measurement of retinal nerve fibre layer thickness (RNFLT) and macula thickness (MT) and, in addition, is suitable to measure volumes (e.g., macula volume/MV). In the research of neurodegenerative diseases, OCT has been increasingly used and has shown its potential as a possible diagnostic tool over the course of the last few years. In recent years, the hypothesis that mental disorders like schizophrenia or unipolar depressive disorder have a degenerative component was established through a variety of volumetric MRI studies. This review article aims to present the method of OCT, to display its recent use in medicine and psychiatry, as well as to examine possible additional applications in the field of psychiatry. PMID:25299627

  8. Correlation between the optical coherence tomography and electroretinogram in retinal vein occlusion macular edema

    Directory of Open Access Journals (Sweden)

    Ya Xu

    2014-11-01

    Full Text Available AIM: To evaluate the correlation between retinal thickness and photopic flash electroretinogram(ERGparameters(Cone a-wave, Cone b-wave, and 30Hz flickerin patients with central retinal vein occlusion(CRVOand macular edema. METHODS: A total of 25 patients(25 CRVO eyes and 25 unaffected fellow eyeswith CRVO underwent the examination of optical coherence tomography(OCTand photopic falsh ERG. The amplitude and implicit time of the ERG parameters were extracted from the ERG traces. Retinal thicknesses were measured by OCT in nine macular subfields. Then the correlations between ERG parameters and macular morphological parameters were analyzed. RESULTS: The Cone b-wave and 30Hz flicker implicit time were correlated with macular retinal thickness in seven out of nine subfields, excluding the temporal subfields. CONCLUSION: The retinal thickness of the macular edema may be associated with inner retinal function in CRVO patients.

  9. In vivo Imaging of Sarcoptes scabiei Infestation Using Optical Coherence Tomography

    DEFF Research Database (Denmark)

    Banzhaf, Christina Alette; Themstrup, Lotte

    2013-01-01

    BACKGROUND: Sarcoptes scabiei can be visualized with different imaging tools. Optical coherence tomography (OCT) may have the potential to describe the changes in skin morphology due to scabies infestation and visualize the parasite. METHODS: Five patients from the Departments of Dermatology, Augsburg, Germany, and Roskilde, Denmark, were OCT scanned (VivoSight(®); Michelson Diagnostics Ltd., UK). Mites were identified by epiluminescence and light microscopy to confirm the diagnosis. RESULTS: OCT identified S. scabiei mites in all patients in vivo. Mites and burrows were visualized, and some detail on burrow content was provided. CONCLUSION: OCT can visualize S. scabiei mites in vivo, suggesting that it may be used to study the biology of the mites in vivo and provide early assessment of scabicide therapy. OCT is able to visualize structures in the skin with an 8-?m resolution. Therefore, this technology could potentially allow rapid, non-invasive, in vivo diagnosis and analysis of infestations.

  10. Concurrent multiscale imaging with magnetic resonance imaging and optical coherence tomography

    Science.gov (United States)

    Liang, Chia-Pin; Yang, Bo; Kim, Il Kyoon; Makris, George; Desai, Jaydev P.; Gullapalli, Rao P.; Chen, Yu

    2013-04-01

    We develop a novel platform based on a tele-operated robot to perform high-resolution optical coherence tomography (OCT) imaging under continuous large field-of-view magnetic resonance imaging (MRI) guidance. Intra-operative MRI (iMRI) is a promising guidance tool for high-precision surgery, but it may not have sufficient resolution or contrast to visualize certain small targets. To address these limitations, we develop an MRI-compatible OCT needle probe, which is capable of providing microscale tissue architecture in conjunction with macroscale MRI tissue morphology in real time. Coregistered MRI/OCT images on ex vivo chicken breast and human brain tissues demonstrate that the complementary imaging scales and contrast mechanisms have great potential to improve the efficiency and the accuracy of iMRI procedure.

  11. Automatic detection of stent struts with thick neointimal growth in intravascular optical coherence tomography image sequences

    Science.gov (United States)

    Xu, Chenyang; Schmitt, Joseph M.; Akasaka, Takashi; Kubo, Takashi; Huang, Kun

    2011-10-01

    To assist cardiologists investigating neointimal tissue growth on stents during follow-up with optical coherence tomography (OCT), we developed an automatic algorithm to locate deeply buried stent struts and to quantify the restenosis burden. The technique is based on an improved steerable filter for computing the local ridge strength and orientation. It also uses an ellipsoid fitting algorithm and continuity criteria to obtain globally optimal stent localization. The restenosis burden calculations were compared to manual assessment of OCT coronary artery image data obtained from in vivo human clinical studies. Compared to manual assessment by expert readers, the algorithm operated with > 97% accuracy in the measurement of mean and maximum restenosis burden. The results indicated that the technique yielded comparable accuracy in measuring restenosis burden, and significantly reduced user interaction time.

  12. MONSTIR II: A 32-channel, multispectral, time-resolved optical tomography system for neonatal brain imaging

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, Robert J., E-mail: robert.cooper@ucl.ac.uk; Magee, Elliott; Everdell, Nick; Magazov, Salavat; Varela, Marta; Airantzis, Dimitrios; Gibson, Adam P.; Hebden, Jeremy C. [Biomedical Optics Research Laboratory, Department of Medical Physics and Bioengineering, University College London, London WC1E 6BT (United Kingdom)

    2014-05-15

    We detail the design, construction and performance of the second generation UCL time-resolved optical tomography system, known as MONSTIR II. Intended primarily for the study of the newborn brain, the system employs 32 source fibres that sequentially transmit picosecond pulses of light at any four wavelengths between 650 and 900 nm. The 32 detector channels each contain an independent photo-multiplier tube and temporally correlated photon-counting electronics that allow the photon transit time between each source and each detector position to be measured with high temporal resolution. The system's response time, temporal stability, cross-talk, and spectral characteristics are reported. The efficacy of MONSTIR II is demonstrated by performing multi-spectral imaging of a simple phantom.

  13. Ball lens based lensed patch cord probes for optical coherence tomography in the field of dentistry

    Science.gov (United States)

    Eom, J. B.; Kim, Y.; Lee, S. J.; Min, E. J.; Park, S. J.; Lee, B. H.

    2012-10-01

    A lensed patch cord probe has been made with a ball lens packaged in a metal cylinder. By simply placing a ball lens directly in front of a fiber patch cord, a compact and potentially disposable sampling probe for optical coherence tomography (OCT) could be implemented. To achieve a sufficiently long working distance and a good transverse resolution simultaneously, the proper ball lens diameter and the distance between the ball lens and the fiber patch cord were investigated. Experimentally, a working distance of up to 5.2 mm, 3 dB bandwidth of 2 mm, and transverse resolution of 16 ?m were achieved. With the patch cord probe, a common path swept source OCT system was implemented and used to demonstrate the feasibility as the dedicated probe for dentistry.

  14. Visualized numerical assessment for near infrared diffuse optical tomography with contrast-and-size detail analysis

    Science.gov (United States)

    Chen, Liang-Yu; Pan, Min-Cheng; Pan, Min-Chun

    2013-01-01

    The purpose of this study is to propose an objective contrast-and-size detail (CSD) analysis for near infrared diffuse optical tomography (NIR DOT), of which the concept is derived from the subjective contrast detail (CD) analysis. We define a measure for numerical CSD analysis based on the resolution estimation of contrast and size. Following that, the contrast-and-size map of resolution can be calculated and displayed for each corresponding image in the map; furthermore, a CSD resolution curve can be plotted by calculating the average value of the projection corresponding to the physical quantity/axis (size or contrast). To provide some worked examples about the proposed CSD analysis evaluating the imaging performance of different reconstruction methods, Tikhonov regularization and edge-preserving regularization with different weighting functions were employed. Results suggested that using edge-preserving regularization with the generalized Lorentzian weighting function is the most attractive for the estimation of absorption-coefficient images.

  15. A Fast Reconstruction Algorithm for Fluorescence Optical Diffusion Tomography Based on Preiteration

    Directory of Open Access Journals (Sweden)

    Xiaolei Song

    2007-04-01

    Full Text Available Fluorescence optical diffusion tomography in the near-infrared (NIR bandwidth is considered to be one of the most promising ways for noninvasive molecular-based imaging. Many reconstructive approaches to it utilize iterative methods for data inversion. However, they are time-consuming and they are far from meeting the real-time imaging demands. In this work, a fast preiteration algorithm based on the generalized inverse matrix is proposed. This method needs only one step of matrix-vector multiplication online, by pushing the iteration process to be executed offline. In the preiteration process, the second-order iterative format is employed to exponentially accelerate the convergence. Simulations based on an analytical diffusion model show that the distribution of fluorescent yield can be well estimated by this algorithm and the reconstructed speed is remarkably increased.

  16. Compound prism design principles, III: linear-in-wavenumber and optical coherence tomography prisms

    Science.gov (United States)

    Hagen, Nathan; Tkaczyk, Tomasz S.

    2011-01-01

    We extend the work of the first two papers in this series [Appl. Opt. 50, 4998–5011 (2011), Appl. Opt. 50, 5012–5022 (2011)] to design compound prisms for linear-in-wavenumber dispersion, especially for application in spectral domain optical coherence tomography (OCT). These dispersive prism designs are believed to be the first to meet the requirements of high resolution OCT systems in direct-view geometry, where they can be used to shrink system size, to improve light throughput, to reduce stray light, and to reduce errors resulting from interpolating between wavelength- and wavenumber-sampled domains. We show prism designs that can be used for thermal sources or for wideband superluminescent diodes centered around wavelengths 850, 900, 1300, and 1375 nm. PMID:22423147

  17. Accelerated simulation of optical coherence tomography of objects with arbitrary spatial distributions

    Science.gov (United States)

    Escobar I., Mauricio R.; Malektaji, Siavash; Lima, Ivan T.; Sherif, Sherif S.

    2014-09-01

    We developed a highly parallel simulator of Optical Coherence Tomography (OCT) of objects with arbitrary spatial distributions. This Monte Carlo method based simulator models the object as a tetrahedron-based mesh, and implements an advanced importance sampling scheme. This new method makes OCT simulations more practical, since the corresponding serial Central Processing Unit (CPU) based implementation requires approximately 360 hours to simulate OCT imaging of a single B-scan. We implemented this new simulator on Graphics Processing Units (GPUs) using the Compute Unified Device Architecture (CUDA) platform and programming model by NVIDIA. We demonstrated that our new simulator requires one order of magnitude less time, compared to its serial implementation, to simulate the same OCT images. Our new parallel OCT simulator could be an important and practical tool to study different OCT phenomena and to design novel OCT systems with superior imaging performance.

  18. Application of optical coherence tomography for noninvasive blood glucose monitoring during hyperglycemia

    Science.gov (United States)

    Larin, Kirill V.; Ashitkov, Taras V.; Motamedi, Massoud; Esenaliev, Rinat O.

    2003-10-01

    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 chemical analysis. Recently we proposed to use optical coherence tomography (OCT) for continuous noninvasive blood glucose sensing through skin. In this paper we tested the OCT technique for noninvasive monitoring of blood glucose concentration in lip tissue of New Zealand rabbits and Yucatan micropigs during glucose clamping experiments. Obtained results show good agreement with results obtained in skin studies, good correlation of changes in the OCT signal slope measured at the depth of 250 to 500 ?m with changes in blood glucose concentration, and higher stability of the OCT data points than that obtained from skin.

  19. Utilizing optical coherence tomography for CAD/CAM of indirect dental restorations

    Science.gov (United States)

    Chityala, Ravishankar; Vidal, Carola; Jones, Robert

    Optical Coherence Tomography (OCT) has seen broad application in dentistry including early carious lesion detection and imaging defects in resin composite restorations. This study investigates expanding the clinical usefulness by investigating methods to use OCT for obtaining three-dimensional (3D) digital impressions, which can be integrated to CAD/CAM manufacturing of indirect restorations. 3D surface topography `before' and `after' a cavity preparation was acquired by an intraoral cross polarization swept source OCT (CP-OCT) system with a Micro-Electro-Mechanical System (MEMS) scanning mirror. Image registration and segmentation methods were used to digitally construct a replacement restoration that modeled the original surface morphology of a hydroxyapatite sample. After high resolution additive manufacturing (e.g. polymer 3D printing) of the replacement restoration, micro-CT imaging was performed to examine the marginal adaptation. This study establishes the protocol for further investigation of integrating OCT with CAD/CAM of indirect dental restorations.

  20. Geometric deformable model driven by CoCRFs: application to optical coherence tomography.

    Science.gov (United States)

    Tsechpenakis, Gabriel; Lujan, Brandon; Martinez, Oscar; Gregori, Giovanni; Rosenfeld, Philip J

    2008-01-01

    We present a geometric deformable model driven by dynamically updated probability fields. The shape is defined with the signed distance function, and the internal (smoothness) energy consists of a C1 continuity constraint, a shape prior, and a term that forces the zero-level of the shape distance function towards a connected form. The image probability fields are estimated by our collaborative Conditional Random Field (CoCRF), which is updated during the evolution in an active learning manner: it infers class posteriors in pixels or regions with feature ambiguities by assessing the joint appearance of neighboring sites and using the classification confidence. We apply our method to Optical Coherence Tomography fundus images for the segmentation of geographic atrophies in dry age-related macular degeneration of the human eye. PMID:18979829

  1. Spectrometer based Fourier domain optical coherence tomography of the mouse retina

    Science.gov (United States)

    Xu, Jing; Khorasani, Mohammadali H.; Koo, Jimmy N. B.; Sarunic, Marinko V.

    2008-02-01

    We present a custom Fourier Domain Optical Coherence Tomography (FDOCT) system adapted to imaging the retinal structures in mice. The FDOCT system utilized spectrometer detection, and operated at a central wavelength of 826nm with a FWHM spectral bandwidth of 72nm, corresponding to an axial resolution of ~4microns (in air). A custom hand-held probe was constructed providing adjustable focusing and increased maneuverability over fixed systems to facilitate coupling of the raster scanned beam into the mouse eye. Image acquisition and display was performed in real time using custom written, multi-threaded software package which displays two dimensional B-scans. Cross sectional images of mouse retina, acquired in vivo an anesthetized animals, are presented.

  2. Speckle reduction during all-fiber common-path optical coherence tomography of the cavernous nerves

    Science.gov (United States)

    Chitchian, Shahab; Fiddy, Michael; Fried, Nathaniel M.

    2009-02-01

    Improvements in identification, imaging, and visualization of the cavernous nerves during prostate cancer surgery, which are responsible for erectile function, may improve nerve preservation and postoperative sexual potency. In this study, we use a rat prostate, ex vivo, to evaluate the feasibility of optical coherence tomography (OCT) as a diagnostic tool for real-time imaging and identification of the cavernous nerves. A novel OCT system based on an all single-mode fiber common-path interferometer-based scanning system is used for this purpose. A wavelet shrinkage denoising technique using Stein's unbiased risk estimator (SURE) algorithm to calculate a data-adaptive threshold is implemented for speckle noise reduction in the OCT image. The signal-to-noise ratio (SNR) was improved by 9 dB and the image quality metrics of the cavernous nerves also improved significantly.

  3. Combined image-processing algorithms for improved optical coherence tomography of prostate nerves

    Science.gov (United States)

    Chitchian, Shahab; Weldon, Thomas P.; Fiddy, Michael A.; Fried, Nathaniel M.

    2010-07-01

    Cavernous nerves course along the surface of the prostate gland and are responsible for erectile function. These nerves are at risk of injury during surgical removal of a cancerous prostate gland. In this work, a combination of segmentation, denoising, and edge detection algorithms are applied to time-domain optical coherence tomography (OCT) images of rat prostate to improve identification of cavernous nerves. First, OCT images of the prostate are segmented to differentiate the cavernous nerves from the prostate gland. Then, a locally adaptive denoising algorithm using a dual-tree complex wavelet transform is applied to reduce speckle noise. Finally, edge detection is used to provide deeper imaging of the prostate gland. Combined application of these three algorithms results in improved signal-to-noise ratio, imaging depth, and automatic identification of the cavernous nerves, which may be of direct benefit for use in laparoscopic and robotic nerve-sparing prostate cancer surgery.

  4. Spatial resolution and scanning time in the optical tomography of absorbing 'phantoms' under multiple scattering conditions

    International Nuclear Information System (INIS)

    Photon-counting optical tomography was used in the visualisation and projective reconstruction of the image of a strongly absorbing inclusion (a 'phantom'), 6 mm in diameter, hidden by multiple scattering processes in a model object (diameter 140 mm, absorption and scattering coefficients 0.005 and 1.4 mm-1, respectively). It was demonstrated experimentally that when the probe radiation power was 10 - 13 mW the minimal (corresponding to the poorest signal/noise ratio ?1) measurement time (photon-counting time) was 0.8 s per one measurement point and the total time needed to scan the whole object was less than 410 s. (laser applications and other topics in quantum electronics)

  5. A 3D Segmentation Method for Retinal Optical Coherence Tomography Volume Data

    CERN Document Server

    Sun, Yankui

    2012-01-01

    With the introduction of spectral-domain optical coherence tomography (OCT), much larger image datasets are routinely acquired compared to what was possible using the previous generation of time-domain OCT. Thus, the need for 3-D segmentation methods for processing such data is becoming increasingly important. We present a new 3D segmentation method for retinal OCT volume data, which generates an enhanced volume data by using pixel intensity, boundary position information, intensity changes on both sides of the border simultaneously, and preliminary discrete boundary points are found from all A-Scans and then the smoothed boundary surface can be obtained after removing a small quantity of error points. Our experiments show that this method is efficient, accurate and robust.

  6. Rapid two-dimensional transversal scanning fiber probe for optical coherence tomography

    Science.gov (United States)

    Huang, Gang; Ding, Zhihua

    2007-02-01

    A fiber probe that is capable of two-dimensional traversal scanning is developed and implemented to a time-domain optical coherence tomography (OCT). Due to its geometrical structure, the fiber cantilever of the probe has two intrinsic resonant frequencies. When the probe is base-excited by signal with two mixed frequencies near the resonances, traversal scanning pattern is generated with controllable area coverage through fine tuning of frequency ratio and fetching period. A position sensitive detector is introduced in the probe to record the real-time trajectory of the scanning pattern for image reconstruction. Fast OCT images of samples including rule, coin and leaf are obtained with the developed probe applied to our time-domain OCT setup. We envision obtaining rapid three-dimensional imaging with the developed probe in a Fourier domain OCT system.

  7. Optical coherence tomography layer thickness characterization of a mock artery during angioplasty balloon deployment

    Science.gov (United States)

    Azarnoush, Hamed; Vergnole, Sébastien; Boulet, Benoît; Lamouche, Guy

    2011-03-01

    Optical coherence tomography (OCT) is used to study the deformation of a mock artery in an angioplasty simulation setup. An OCT probe integrated in a balloon catheter provides intraluminal real-time images during balloon inflation. Swept-source OCT is used for imaging. A 4 mm semi-compliant polyurethane balloon is used for experiments. The balloon is inflated inside a custom-built multi-layer artery phantom. The phantom has three layers to mock artery layers, namely, intima, media and adventitia. Semi-automatic segmentation of phantom layers is performed to provide a detailed assessment of the phantom deformation at various inflation pressures. Characterization of luminal diameter and thickness of different layers of the mock artery is provided for various inflation pressures.

  8. Remineralization of root caries monitored using cross polarization optical coherence tomography

    Science.gov (United States)

    Darling, Cynthia L.; Staninec, Michal; Chan, Kenneth H.; Kang, Hobin; Fried, Daniel

    2012-01-01

    Previous studies have demonstrated that polarization sensitive optical coherence tomography (PS-OCT) can be used to image caries lesions in dentin, measure nondestructively the severity of dentin demineralization, and determine the efficacy of intervention with anticaries agents including fluoride and lasers. However, those studies were limited to artificial lesions on dentin and roots surfaces. The objective of this study is to determine if a cross polarization OCT system (CP-OCT) can be used to nondestructively measure a reduction in the reflectivity of natural root caries lesions after exposure to a remineralization solution. CPOCT images of 11 teeth with existing root lesions were acquired before and after exposure to a remineralizing solution for 20 days. The integrated reflectivity was calculated after integrating to a fixed depth of 200-?m. There was a significant decrease in the integrated reflectivity after exposure to the remineralizing solution.

  9. Nondestructive assessment of current one-step self-etch dental adhesives using optical coherence tomography.

    Science.gov (United States)

    Bista, Baba; Sadr, Alireza; Nazari, Amir; Shimada, Yasushi; Sumi, Yasunori; Tagami, Junji

    2013-07-01

    ABSTRACT. This study aimed to nondestructively evaluate sealing performance of eight one-step self-etch adhesives (1-SEAs) using optical coherence tomography (OCT). The two-step self-etch adhesive (2-SEA) served as the control. Round tapered class-I cavities (D=4 mm, H=2 mm) were prepared in bovine incisors, treated with each adhesive (n=5), and restored with a flowable resin composite. Cross-sections were obtained from each restoration using swept-source OCT with 1310-nm laser. The average percentage of the sealed interface (SI%) for each adhesive was calculated using image analysis software, considering increased signal intensity at the interface as gap. Samples were then sectioned and observed under confocal laser scanning microscope (CLSM). Significantly different SI% values were found among different adhesives (analysis of variance, Bonferroni, pbeam. PMID:23887479

  10. Overcoming barriers in topical administration of gold nanoparticles for optical coherence tomography using multimodal delivery

    Science.gov (United States)

    Kim, Chang Soo; Wilder-Smith, Petra; Ahn, Yeh-Chan; Liaw, Lih-Huei L.; Chen, Zhongping; Kwon, Young Jik

    2010-02-01

    Optical coherence tomography (OCT) is a non-invasive and promising imaging modality with high resolution that is an order of magnitude higher than current diagnostic techniques. However, its use in detecting early-stage cancer is limited due to insufficient contrast level in biological tissue, which can be enhanced by harnessing contrast agents [e.g., gold nanoparticles (Au NPs)]. Enhanced penetration by creating micropassages and distribution by ultrasonic force (multimodal topical delivery) was proven to overcome two major barriers (stratum corneum and epithelial barriers) in topically administering Au NPs using an in vivo oral dysplasia hamster model (overall 150% enhanced OCT contrast). Expanded progress on a highly efficient and versatile Au NP-releasing polymer microneedle platform showed a promising next generation multi-modal delivery of Au NPs.

  11. How histological features of basal cell carcinomas influence image quality in optical coherence tomography

    DEFF Research Database (Denmark)

    Mogensen, Mette; Nürnberg, Birgit M.

    2011-01-01

    Optical coherence tomography (OCT) has the potential to diagnose and measure the depth of nonmelanoma skin cancer (NMSC) in skin, but some lesions appear blurred in OCT images. The aim of this study is to identify histological characteristics of basal cell carcinomas (BCC) that correlate with good quality OCT images of the same lesions. A total of 34 patients with BCC were OCT scanned. The influence of histology parameters (e.g. inflammation, sun damage of skin, carcinoma cell size) on OCT image quality was studied by comparing 15 BCC lesions easily identified compared to 19 BCC lesions that produced only blurred in OCT images. Inflammation was more pronounced in blurred OCT images, whereas solar elastosis dominated in easily identified lesions. Hyperkeratosis did not impair imaging significantly. OCT image quality of BCC may depend on specific histology parameters.

  12. En face parametric imaging of tissue birefringence using polarization-sensitive optical coherence tomography

    Science.gov (United States)

    Chin, Lixin; Yang, Xiaojie; McLaughlin, Robert A.; Noble, Peter B.; Sampson, David D.

    2013-06-01

    A technique for generating en face parametric images of tissue birefringence from scans acquired using a fiber-based polarization-sensitive optical coherence tomography (PS-OCT) system utilizing only a single-incident polarization state is presented. The value of birefringence is calculated for each A-scan in the PS-OCT volume using a quadrature demodulation and phase unwrapping algorithm. The algorithm additionally uses weighted spatial averaging and weighted least squares regression to account for the variation in phase accuracies due to varying OCT signal-to-noise-ratio. The utility of this technique is demonstrated using a model of thermally induced damage in porcine tendon and validated against histology. The resulting en face images of tissue birefringence are more useful than conventional PS-OCT B-scans in assessing the severity of tissue damage and in localizing the spatial extent of damage.

  13. Automated quantification of colonic crypt morphology using integrated microscopy and optical coherence tomography.

    Science.gov (United States)

    Qi, Xin; Pan, Yinsheng; Hu, Zhilin; Kang, Wei; Willis, Joseph E; Olowe, Kayode; Sivak, Michael V; Rollins, Andrew M

    2008-01-01

    Colonic crypt morphological patterns have shown a close correlation with histopathological diagnosis. Imaging technologies such as high-magnification chromoendoscopy and endoscopic optical coherence tomography (OCT) are capable of visualizing crypt morphology in vivo. We have imaged colonic tissue in vitro to simulate high-magnification chromoendoscopy and endoscopic OCT and demonstrate quantification of morphological features of colonic crypts using automated image analysis. 2-D microscopic images with methylene blue staining and correlated 3-D OCT volumes were segmented using marker-based watershed segmentation. 2-D and 3-D crypt morphological features were quantified. The accuracy of segmentation was validated, and measured features are in agreement with known crypt morphology. This work can enable studies to determine the clinical utility of high-magnification chromoendoscopy and endoscopic OCT, as well as studies to evaluate crypt morphology as a biomarker for colonic disease progression. PMID:19021435

  14. Optical coherence tomography investigation of ischemic stroke inside a rodent model.

    Science.gov (United States)

    Osiac, Eugen; B?l?eanu, Tudor Adrian; Mogoant?, Lauren?iu; Gheonea, Dan Ionu?; Pirici, Ionica; Ianc?u, Maria; Mitran, Smaranda Ioana; Albu, Carmen Valeria; C?t?lin, Bogdan; Sfredel, Veronica

    2014-01-01

    Although already in use in several medical domains, only recently optical coherence tomography (OCT) has been applied in the study of ischemic events. In this paper, we will focus on characterizing ischemic stroke, in a rat model, by OCT. Investigations were carried on a set of 25 rats, on which ischemic stroke was inflicted by a transient occlusion of the middle cerebral artery (tMCAO). Animals were sacrificed 1, 3, 7 and 28 days after occlusion. We tested the OCT's power of detection and discrimination of stroke area compared to both normal, contralateral hemisphere and non-affected brain tissue, together with the aid of histochemical and pathological examination. Our results show a great potential of OCT to be used as a detection tool in acute and chronic phases of stroke. PMID:25329101

  15. Optimal sparsifying bases for frequency-domain optical-coherence tomography.

    Science.gov (United States)

    Nayak, Rohit; Seelamantula, Chandra Sekhar

    2012-12-01

    We address the reconstruction problem in frequency-domain optical-coherence tomography (FDOCT) from undersampled measurements within the framework of compressed sensing (CS). Specifically, we propose optimal sparsifying bases for accurate reconstruction by analyzing the backscattered signal model. Although one might expect Fourier bases to be optimal for the FDOCT reconstruction problem, it turns out that the optimal sparsifying bases are windowed cosine functions where the window is the magnitude spectrum of the laser source. Further, the windowed cosine bases can be phase locked, which allows one to obtain higher accuracy in reconstruction. We present experimental validations on real data. The findings reported in this Letter are useful for optimal dictionary design within the framework of CS-FDOCT. PMID:23202086

  16. Study on intra-retinal layers imaged with ultra-high resolution optical coherence tomography

    Directory of Open Access Journals (Sweden)

    Su-Zhong Xu

    2014-08-01

    Full Text Available To evaluate the automated segmentation algorithm for detection of intra-retinal layers to process images obtained from ultra-high resolution optical coherence tomography(OCT. Graph theory and the shortest path search based on dynamic programming were applied to automatically segment the 8 intra-retinal layers. We experimentally verified the accuracy and reliability of the algorithm. The results showed that the intra-retinal layer boundaries between automated and manual segmentations matched well. The algorithm successfully segmented the intra-retinal layers in glaucoma, high myopia, and retinitis pigmentosa patients. The proposed automatic segmentation for intra-retinal layers provides a promising tool for quantitative analysis in clinical diagnosis and treatment.

  17. In vivo Evaluation of Enamel Dental Restoration Interface by Optical Coherence Tomography

    International Nuclear Information System (INIS)

    In this work, we report in vivo application of Optical Coherence Tomography (OCT) to assess dental restorations in humans. After approval by the Ethical Committee in Humans Research of the Federal University of Pernambuco, thirty patients with resin composite restorations performed in anterior teeth were selected. The patients were clinically evaluated, and OCT was performed. Images were obtained using OCT operating in the spectral domain, with a 840 nm super luminescent diode light source (spectral width of 50 nm, fiber output power 25mW and a measured spatial resolution of 10 ?m). The image acquisition time was less than one second. The results were analyzed with respect to the integrity and marginal adaptation of the restoration. Using appropriate software, the lesion region can be exactly located and a new restoration procedure can be carried out. We have shown that OCT is more than adequate in clinical practice to assess dental restorations. (Author)

  18. Versatile confocal/optical coherence tomography system for embryonic developmental imaging

    Science.gov (United States)

    Bradu, A.; Ma, Lisha; Bloor, J.; Podoleanu, A.

    2008-02-01

    An Optical Coherence Tomography (OCT) imaging system has been designed and constructed to acquire images of scattering biological samples. By simultaneously acquiring and displaying high resolution en-face (C-scan) OCT and Laser Scanning Confocal images of Drosophila melanogaster embryos we demonstrate the potential of the system to be used as a powerful tool for imaging in Drosophila embryonic development. The system can equally be used for non invasive visualizations and measurements of the movement of Drosophila melanogaster larval heart and can easily be switched in the OCT B-scan regime. The confocal channel adds guidance as the specimen can be quickly located and this makes the use of the system in a large scale gene screen feasible.

  19. New Insight into Rheology and Flow Properties of Complex Fluids with Doppler Optical Coherence Tomography

    Directory of Open Access Journals (Sweden)

    JuhaSalmela

    2014-05-01

    Full Text Available Flow properties of complex fluids such as colloidal suspensions, polymer solutions, fiber suspensions and blood have a vital function in many technological applications and biological systems. Yet, the basic knowledge on their properties is inadequate for many practical purposes. One important reason for this has been the lack of effective experimental methods that would allow detailed study of the flow behavior of especially opaque multi-phase fluids. Optical Coherence Tomography (OCT is an emerging technique capable of simultaneous measurement of the internal structure and motion of most opaque materials, with resolution in the micrometer scale and measurement frequency up to 100 kHz. This mini-review will examine the recent results on the use of Doppler-OCT in the context of flows and rheological properties of complex fluids outside biomedical field.

  20. 3D Polymer Weld Seam Characterization Based on Optical Coherence Tomography for Laser Transmission Welding Applications

    Science.gov (United States)

    Schmitt, Robert; Mallmann, Guilherme; Devrient, Martin; Schmidt, Michael

    Laser transmission welding is an established single-stage plastic joining process, which enables hermetically sealed joints under the workpiece surface. The process requires joining partners with proper degrees of transmission and absorption to the processing wavelength. For reaching a stable process an in-process quality assurance is very valuable. Current monitoring systems have a limited usage, as no quantitative information of the weld itself is obtained without its destruction. In medical and pharmaceutical applications a weld with leakage is e.g. unacceptable. The main objective of this paper is the presentation of the optical coherence tomography as a tool for the quality assurance in laser transmission welding. This approach enables the measurement of any residual gap, weld geometry, internal pores and leaks. The presented results show that this technique allows even the characterization of welds using joining partners with thicknesses of 2 mm or with glass fiber reinforcement levels of 30% per weight.

  1. Optical coherence tomography of the intracranial vasculature and Wingspan stent in a patient.

    Science.gov (United States)

    Given, Curtis Alden; Ramsey, Christian Norman; Attizzani, Guilherme Ferragut; Jones, Michael R; Brooks, William H; Bezerra, Hiram G; Costa, Marco A

    2015-06-01

    A 67-year-old man with medically refractory vertebrobasilar insufficiency and short segment occlusions of the intracranial vertebral arteries was treated with angioplasty and stent placement. Fifteen hours after the procedure the patient developed symptoms of posterior fossa ischemia and repeat angiography showed thrombus formation within the stent which was treated with thrombolytic and aggressive antiplatelet therapy. Angiography revealed lysis of the clot, but concerns regarding the mechanism of the thrombotic phenomenon prompted frequency-domain optical coherence tomography (FDOCT) assessment. FDOCT provided excellent visualization of the stent and vessel wall interactions, as well as excluding residual flow-limiting stenosis, obviating the need for further intervention. The potential utility of FDOCT in the evaluation of intracranial atherosclerotic disease and additional intracranial applications are discussed. PMID:24847090

  2. Quantitative optical coherence tomography imaging of intermediate flow defect phenotypes in ciliary physiology and pathophysiology

    Science.gov (United States)

    Huang, Brendan K.; Gamm, Ute A.; Jonas, Stephan; Khokha, Mustafa K.; Choma, Michael A.

    2015-03-01

    Cilia-driven fluid flow is a critical yet poorly understood aspect of pulmonary physiology. Here, we demonstrate that optical coherence tomography-based particle tracking velocimetry can be used to quantify subtle variability in cilia-driven flow performance in Xenopus, an important animal model of ciliary biology. Changes in flow performance were quantified in the setting of normal development, as well as in response to three types of perturbations: mechanical (increased fluid viscosity), pharmacological (disrupted serotonin signaling), and genetic (diminished ciliary motor protein expression). Of note, we demonstrate decreased flow secondary to gene knockdown of kif3a, a protein involved in ciliogenesis, as well as a dose-response decrease in flow secondary to knockdown of dnah9, an important ciliary motor protein.

  3. Miniaturized magnetic-driven scanning probe for endoscopic optical coherence tomography.

    Science.gov (United States)

    Pang, Ziwei; Wu, Jigang

    2015-06-01

    We designed and implemented a magnetic-driven scanning (MDS) probe for endoscopic optical coherence tomography (OCT). The probe uses an externally-driven tiny magnet in the distal end to achieve unobstructed 360-degree circumferential scanning at the side of the probe. The design simplifies the scanning part inside the probe and thus allows for easy miniaturization and cost reduction. We made a prototype probe with an outer diameter of 1.4 mm and demonstrated its capability by acquiring OCT images of ex vivo trachea and artery samples from a pigeon. We used a spectrometer-based Fourier-domain OCT system and the system sensitivity with our prototype probe was measured to be 91 dB with an illumination power of 850 ?W and A-scan exposure time of 1 ms. The axial and lateral resolutions of the system are 6.5 ?m and 8.1 ?m, respectively. PMID:26114041

  4. Imaging late capsular bag distension syndrome: an anterior segment optical coherence tomography study

    Directory of Open Access Journals (Sweden)

    Tan YL

    2012-09-01

    Full Text Available Yar Li Tan,1,2 Lakshmanasamudram S Mohanram,1 Seng Ei Ti,1,2 Tin Aung,1–3 Shamira Perera1,21Singapore National Eye Centre, 2Singapore Eye Research Institute, 3National University of Singapore, Yong Loo Lin School of Medicine, Buona Vista, SingaporeBackground: Anterior segment optical coherence tomography (ASOCT was used to categorize and provide insights into the etiology of capsular bag distension syndrome (CBDS.Methods: A prospective review was undertaken of 10 cases who presented with signs of late CBDS 5–11 years after uneventful phacoemulsification with in-the-bag posterior chamber intraocular lens implantation.Results: All 10 patients presented with a milky collection within the distended capsular bag without raised intraocular pressure or a shallow anterior chamber. ASOCT was used to confirm the diagnosis in all cases, and a hyperintense signal was seen in the space between the posterior chamber intraocular lens and the posteriorly bowed posterior capsule. The continuous curvilinear capsulorhexis was measured to be between 3.18 mm and 4.70 mm. Three cases had uncorrected visual acuity better than 6/12. Uncomplicated Neodymium-doped Yttrium Aluminium Garnet (Nd:YAG posterior capsulotomy was performed in eight patients, with no resulting change in the intraocular lens position (measured by ASOCT or subjective refraction.Conclusion: Our study showed that ASOCT is a useful modality to differentiate this condition clearly from posterior chamber intraocular lens opacification and to investigate its causation. Nd:YAG posterior capsulotomy proved to be a safe and successful treatment for late CBDS with no change in biometric or refractive parameters.Keywords: anterior segment optical coherence tomography, capsular bag distension syndrome, YAG capsulotomy

  5. Evaluation of dacryocystorhinostomy using optical coherence tomography and rebamipide ophthalmic suspension

    Directory of Open Access Journals (Sweden)

    Fujimoto M

    2014-08-01

    Full Text Available Masahiro Fujimoto,1 Ken Ogino,1 Chika Miyazaki,1,2 Miou Hirose,1,3 Hiroko Matsuyama,1,4 Takeshi Moritera,1,5 Nagahisa Yoshimura1 1Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan; 2Department of Ophthalmology, Hyogo Prefectural Tsukaguchi Hospital, Hyogo, Japan; 3Department of Ophthalmology, Hyogo Prefectural Amagasaki Hospital, Hyogo, Japan; 4Department of Ophthalmology, National Hospital Organization Himeji Medical Center, Hyogo, Japan; 5Moritera Eye Clinic, Shiga, Japan Purpose: To evaluate the surgical outcome of dacryocystorhinostomy (DCR by measuring the tear meniscus, using optical coherence tomography and rebamipide ophthalmic suspension. Methods: Patients with nasolacrimal obstruction and chronic dacryocystitis who were scheduled for an endonasal DCR underwent tear meniscus examinations before and 2 months after surgery. Vertical scans of the inferior menisci were performed before and at 1, 3, 5, 7, and 10 minutes after the instillation of rebamipide ophthalmic suspension. The tear menisci areas were measured with imaging software. Ten young adults without epiphora formed the control group.Results: Anatomical success was achieved on 22 sides of 21 patients. The patients’ postoperative tear menisci were significantly smaller than the preoperative menisci at all points during the test, and the response to volume loading in the postoperative patients was corrected to nearly that of the young, healthy adults. Nevertheless, the postoperative meniscus area tended to be larger than that of the young adults at all points.Conclusion: The reduced tear meniscus area after DCR reflected the success of the surgical procedure. However, incomplete recovery of the meniscus after the test might suggest a residual disorder of the lacrimal drainage system after DCR. Keywords: dacryocystorhinostomy, tear meniscus, rebamipide, optical coherence tomography

  6. [Chamber Angle Assessment in Clinical Practice - A Comparison between Optical Coherence Tomography and Gonioscopy.

    Science.gov (United States)

    Mösler, M P; Werner, J U; Lang, G K

    2014-12-01

    Background: In glaucoma the structures of the anterior chamber are important for classification, therapy, progression and prognosis. In this context anterior segment optical coherence tomography (AS-OCT) gains more relevance. This study compares AS-OCT with gonioscopy in diagnostic performance of chamber angle (CA) assessment. Patients and Methods: 104 consecutive subjects with glaucoma underwent AS-OCT imaging using the Visante OCT. Results were compared to gonioscopic grading from patient history using the Shaffer system. In addition, anterior chamber depth (ACD) assessment using slitlamp examination was evaluated as a prognostic factor for chamber angle width (CAW) and verified by AS-OCT measurement. Results: Average CAW was 29° (AS-OCT). 17?% of the CAs that were "wide" in gonioscopy (variance 5-55°), showed a "narrow" CA in AS-OCT. 35?% of the CAs that were "narrow" in gonioscopy (variance 0-39°) showed a "wide" CA in AS-OCT. ACD assessment using slitlamp examination is a good predictor for CAW. In this context the technique provides equal informative value as gonioscopy. In cases of "wide" ACDs it is even superior. The critical ACD for an increased risk of angle closure is 2.4?mm. Concerning the critical ACD (optical coherence tomography is an effective alternative to the gold standard and is to some extent even superior. PMID:25462938

  7. Co-registration of optical coherence tomography and X-ray angiography in percutaneous coronary intervention. The Does Optical Coherence Tomography Optimize Revascularization (DOCTOR) fusion study

    DEFF Research Database (Denmark)

    Hebsgaard, Lasse; Nielsen, Troels Munck

    2014-01-01

    BACKGROUND: Intracoronary imaging provides accurate lesion delineation and precise measurements for sizing and positioning of coronary stents. During percutaneous coronary intervention (PCI), it may be challenging to identify corresponding segments between intracoronary imaging and angiography. Computer based online co-registration may aid the target segment identification. METHODS: The DOCTOR fusion study was a prospective, single arm, observational study including patients admitted for elective PCI. Optical coherence tomography (OCT) was acquired pre-stent implantation for sizing of stents. The operator subsequently indicated on the angiogram the target area as identified by OCT. Computer based co-registration was performed on-line immediately after pre-stent acquisition to assess feasibility. The cumulated numerical difference between operator based, and computer based co-registration was assessed as the "Operator Registration Error". The operator implanted the stent blind to the co-registrated angiogram.The difference between the co-registered stent border positions and the actual stent deployment border positions was the "Geographic Miss Distance". RESULTS: Twenty-two patients were included in the study. Two patients were excluded due to missing pre or post-OCT acquisitions. Online co-registration pre-stenting was successful in all analyzed cases. The mean "Operator Registration Error" was 5.4±3.5mm. The mean "Geographic Miss Distance" was 5.4±2.6mm. Without access to the computer-based co-registration, segments of the target lesion indicated on OCT were left uncovered by stent in 14 patients (70%). CONCLUSION: Computer based online co-registration of OCT and angiography is feasible. Frequent inaccuracies in operator based registration indicate that computer aided co-registration may reduce errors in corresponding OCT findings to the angiogram.

  8. Effects of optical clearing agents on noninvasive blood glucose monitoring with optical coherence tomography: a pilot study

    Science.gov (United States)

    He, Ruoyu; Wei, Huajiang; Gu, Huimin; Zhu, Zhengguo; Zhang, Yuqing; Guo, Xiao; Cai, Tiantian

    2012-10-01

    Recently, the capability of optical coherence tomography (OCT) has been demonstrated for noninvasive blood glucose monitoring. In this work, we investigate the administration of chemical agents onto human skin tissue to increase the transparency of the surface of the skin, as a means of improving the capability of OCT imaging for clinically relevant applications. Eight groups of experiments were proposed, in which different optical clearing agents (OCA) were used. The results indicate that, when properly used, some OCAs perform well in promoting the capability of OCT for noninvasive blood glucose monitoring. Among the four kinds of OCA we used, 50% v/v glycerol solute turns out to be the best enhancer. Compared with the results of the experiments in which no OCA was used, when 50% glycerol was applied onto the human skin topically, the correlation coefficient between the OCT signal slope (OCTSS) and blood glucose concentration (BGC) was improved by 7.1% on average, and the lag time between changes in the OCTSS and BGC was cut by 8 min on average. The results of 10 w/v mannitol were also good, but not as pronounced.

  9. Differentiation of oral precancerous stages with optical coherence tomography based on the evaluation of optical scattering properties of oral mucosae

    International Nuclear Information System (INIS)

    Optical coherence tomography (OCT) has been demonstrated to be a powerful tool for noninvasive, real-time oral cancer diagnosis. However, in previous reports, OCT has still been found to be difficult to use in the diagnosis of oral precancerous stages, including mild dysplasia and moderate dysplasia. In clinical applications, early diagnosis and treatment of oral cancer can greatly improve the survival rate. Therefore, in this study, we propose a new approach to differentiate the oral precancerous stages based on the evaluation of the optical scattering properties of the epithelial layer, which is where the dysplastic cells start to develop in the precancerous stages. Instead of using exponential decay fitting to evaluate the scattering properties of mucosal tissues based on the Beer–Lambert law, linear fitting of the OCT depth intensity is used to evaluate the scattering properties of normal and dysplastic cells. From the statistical results of the linear fitting, the slope, a, can be an effective indicator to discriminate healthy mucosa and moderate dysplasia when an a value equal to zero is the threshold value, and the intercept, b, can be used to differentiate healthy and dysplastic mucosae, as well as mild and moderate dysplasia, when b values of 0.15 and 0.18 are used as the threshold values, respectively. Furthermore, this approach is also applied to the determination of the safe margin between normal and abnormal mucosae, making it possible to provide real-time, in vivo inspection during oral maxillofacial surgery. (paper)

  10. 4D optical coherence tomography of the embryonic heart using gated imaging

    Science.gov (United States)

    Jenkins, Michael W.; Rothenberg, Florence; Roy, Debashish; Nikolski, Vladimir P.; Wilson, David L.; Efimov, Igor R.; Rollins, Andrew M.

    2005-04-01

    Computed tomography (CT), ultrasound, and magnetic resonance imaging have been used to image and diagnose diseases of the human heart. By gating the acquisition of the images to the heart cycle (gated imaging), these modalities enable one to produce 3D images of the heart without significant motion artifact and to more accurately calculate various parameters such as ejection fractions [1-3]. Unfortunately, these imaging modalities give inadequate resolution when investigating embryonic development in animal models. Defects in developmental mechanisms during embryogenesis have long been thought to result in congenital cardiac anomalies. Our understanding of normal mechanisms of heart development and how abnormalities can lead to defects has been hampered by our inability to detect anatomic and physiologic changes in these small (organs. Optical coherence tomography (OCT) has made it possible to visualize internal structures of the living embryonic heart with high-resolution in two- and threedimensions. OCT offers higher resolution than ultrasound (30 um axial, 90 um lateral) and magnetic resonance microscopy (25 um axial, 31 um lateral) [4, 5], with greater depth penetration over confocal microscopy (200 um). Optical coherence tomography (OCT) uses back reflected light from a sample to create an image with axial resolutions ranging from 2-15 um, while penetrating 1-2 mm in depth [6]. In the past, OCT groups estimated ejection fractions using 2D images in a Xenopus laevis [7], created 3D renderings of chick embryo hearts [8], and used a gated reconstruction technique to produce 2D Doppler OCT image of an in vivo Xenopus laevis heart [9]. In this paper we present a gated imaging system that allowed us to produce a 16-frame 3D movie of a beating chick embryo heart. The heart was excised from a day two (stage 13) chicken embryo and electrically paced at 1 Hz. We acquired 2D images (B-scans) in 62.5 ms, which provides enough temporal resolution to distinguish end-contraction from end-relaxation. After acquiring the image set, we were able to measure the ejection fraction.

  11. Evaluation of a cheap ultrasonic stage for light source coherence function measurement, optical coherence tomography and dynamic focusing

    International Nuclear Information System (INIS)

    We evaluate the performance of a cheap ultrasonic stage in setups related to optical coherence tomography. The stage was used in several configurations: (1) optical delay line in an optical coherence tomography (OCT) setup; (2) as a delay line measuring coherence function of a low coherence source (e.g. superluminescent diode) and (3) in a dynamic focusing arrangement. The results are as follows: the stage is suitable for coherence function measurement (coherence length up to 70 µm) of the light source and dynamic focusing. We found it unsuitable for OCT due to an unstable velocity profile. Despite this, the velocity profile has a repeatable shape (4% over 1000 A-scans) and slight modifications to the stage promise wider applications. (technical design note)

  12. Novel microscope-integrated stereoscopic display for intrasurgical optical coherence tomography

    Science.gov (United States)

    Shen, Liangbo; Carrasco-Zevallos, Oscar; Keller, Brenton; Viehland, Christian; Waterman, Gar; Desouza, Philip; Hahn, Paul; Kuo, Anthony; Toth, Cynthia A.; Izatt, Joseph A.

    2015-03-01

    The first generation of intrasurgical optical coherence tomography (OCT) systems displayed OCT data onto a separate computer monitor, requiring surgeons to look away from the surgical microscope. In order to provide real-time OCT feedback without requiring surgeons to look away during surgeries, recent prototype research and commercial intrasurgical OCT systems have integrated heads-up display (HUD) systems into the surgical microscopes to allow the surgeons to access the OCT data and the surgical field through the oculars concurrently. However, all current intrasurgical OCT systems with a HUD are only capable of imaging through one ocular limiting the surgeon's depth perception of OCT volumes. Stereoscopy is an effective technology to dramatically increase depth perception by presenting an image from slightly different angles to each eye. Conventional stereoscopic HUD use a pair of micro displays which require bulky optics. Several new approaches for HUDs are reported to use only one micro display at the expense of image brightness or increased footprint. Therefore, these techniques for HUD are not suitable to be integrated into microscopes. We have developed a novel stereoscopic HUD which uses spatial multiplexing to project stereo views into both oculars simultaneously with only one micro-display and three optical elements for our microscope-integrated OCT system. Simultaneous stereoscopic views of OCT volumes are computed in real time by GPU-enabled OCT system software. We present, to our knowledge, the first microscope integrated stereoscopic HUD used for intrasurgical OCT with a novel optical design for stereoscopic viewing devices and report on its preliminary use in human vitreoretinal surgeries.

  13. Co-registered optical coherence tomography and fluorescence molecular imaging for simultaneous morphological and molecular imaging

    International Nuclear Information System (INIS)

    Optical coherence tomography (OCT) provides high-resolution, cross-sectional imaging of tissue microstructure in situ and in real time, while fluorescence molecular imaging (FMI) enables the visualization of basic molecular processes. There is a great deal of interest in combining these two modalities so that the tissue's structural and molecular information can be obtained simultaneously. This could greatly benefit biomedical applications such as detecting early diseases and monitoring therapeutic interventions. In this research, an optical system that combines OCT and FMI was developed. The system demonstrated that it could co-register en face OCT and FMI images with a 2.4 x 2.4 mm2 field-of-view. The transverse resolutions of OCT and FMI of the system are both ?10 ?m. Capillary tubes filled with fluorescent dye Cy 5.5 in different concentrations under a scattering medium are used as the phantom. En face OCT images of the phantoms were obtained and successfully co-registered with FMI images that were acquired simultaneously. A linear relationship between FMI intensity and dye concentration was observed. The relationship between FMI intensity and target fluorescence tube depth measured by OCT images was also observed and compared with theoretical modeling. This relationship could help in correcting reconstructed dye concentration. Imaging of colon polyps of the APCmin mouse model is presented as an example of biological applications of this cle of biological applications of this co-registered OCT/FMI system.

  14. Numerical comparison of different penalty modified barrier functions for optical tomography problems

    Science.gov (United States)

    Roy, Ranadhir

    2009-02-01

    Fluorescent contrast agents have been proposed for near-infrared (NIR) diagnostic breast imaging problems as the most efficient process for inducing optical contrast. We have developed a penalty modified barrier function method (PMBF) with constrained truncated Newton and trust region methods (CONTN) for fluorescence-enhanced NIR diagnostic imaging for both noncontact (area illumination/collection) and contact (point illumination/collection) measurement techniques. A simple logarithmic penalty function has been used in the PMBF/CONTN algorithm with linear convergence. The motivation of this paper is to compare the efficiency and performance of this method with many alternative penalty barrier function methods, (a) hyperbolic penalty function, (b) quadratic-logarithm penalty function, (c) logarithmic exponential penalty function for proper selection of a penalty function that will be the most suitable for optical reconstruction problems. In this paper a numerical comparison of different penalty function methods has been made using experimental measured data in a clinically relevance volume in three-dimensions. Our objective is to continue development of sophisticated constrained optimization PMBF/CONTN method to provide high resolution three dimensional tomography a reality.

  15. Retinal nerve fibre layer thickness measurements in normal Indian population by optical coherence tomography

    Directory of Open Access Journals (Sweden)

    Ramakrishnan R

    2006-01-01

    Full Text Available Purpose: To obtain retinal nerve fibre layer thickness measurements by optical coherence tomography (OCT in normal Indian population. Materials and Methods: Total of 118 randomly selected eyes of 118 normal Indian subjects of both sex and various age groups underwent retinal nerve fiber layer thickness analysis by Stratus OCT 3000 V 4.0.1. The results were evaluated and compared to determine the normal retinal nerve fiber layer thickness measurements and its variations with sex and age. Results: Mean + standard deviation retinal nerve fiber layer thickness for various quadrants of superior, inferior, nasal, temporal, and along the entire circumference around the optic nerve head were 138.2 + 21.74, 129.1 + 25.67, 85.71 + 21, 66.38 + 17.37, and 104.8 + 38.81 µm, respectively. There was no significant difference in the measurements between males and females, and no significant correlation with respect to age. Conclusion: Our results provide the normal retinal nerve fiber layer thickness measurements and its variations with age and sex in Indian population.

  16. Optical coherence tomography detection of shear wave propagation in MCF7 cell modules

    Science.gov (United States)

    Razani, Marjan; Mariampillai, Adrian; Berndl, Elizabeth S. L.; Kiehl, Tim-Rasmus; Yang, Victor X. D.; Kolios, Michael C.

    2014-02-01

    In this work, we explored the potential of measuring shear wave propagation using Optical Coherence Elastography (OCE) in MCF7 cell modules (comprised of MCF7 cells and collagen) and based on a swept-source optical coherence tomography (OCT) system. Shear waves were generated using a piezoelectric transducer transmitting sine-wave bursts of 400 ?s, synchronized with an OCT swept source wavelength sweep imaging system. Acoustic radiation force was applied to the MCF7 cell constructs. Differential OCT phase maps, measured with and without the acoustic radiation force, demonstrate microscopic displacement generated by shear wave propagation in these modules. The OCT phase maps are acquired with a swept-source OCT (SS-OCT) system. We also calculated the tissue mechanical properties based on the propagating shear waves in the MCF7 + collagen phantoms using the Acoustic Radiation Force (ARF) of an ultrasound transducer, and measured the shear wave speed with the OCT phase maps. This method lays the foundation for future studies of mechanical property measurements of breast cancer structures, with applications in the study of breast cancer pathologies.

  17. 800-nm-centered swept laser for spectroscopic optical coherence tomography

    International Nuclear Information System (INIS)

    The isosbestic point of oxy- and deoxy-hemoglobin at 800 nm is an important point in biomedical optical spectroscopic imaging. We have developed a novel swept laser centered at 800 nm and demonstrated its performance for spectroscopic optical coherence tomography. The measured ?10 dB spectral bandwidth of the swept laser was 40 nm and averaged laser output power per sweep was 4 mW. This swept laser was incorporated into our OCT system and used to measure non-scattering liquid phantoms and blood samples. The measured maximum sensitivity and roll-off rate over a range of image depths were 112 dB and ? 1.45 dB mm?1, respectively. The minimum axial resolution of the OCT system was 8.06 ?m at a depth of 2.4 mm. Quantitative and localized absorption spectra were recovered from the non-scattering liquid phantoms. In addition, the measured localized wavelength-dependent attenuation difference of oxygenated and deoxygenated blood was 4.6-fold. (paper)

  18. 800-nm-centered swept laser for spectroscopic optical coherence tomography

    Science.gov (United States)

    Cho, Jaedu; Gulsen, Gultekin; Kim, Chang-Seok

    2014-04-01

    The isosbestic point of oxy- and deoxy-hemoglobin at 800 nm is an important point in biomedical optical spectroscopic imaging. We have developed a novel swept laser centered at 800 nm and demonstrated its performance for spectroscopic optical coherence tomography. The measured ?10 dB spectral bandwidth of the swept laser was 40 nm and averaged laser output power per sweep was 4 mW. This swept laser was incorporated into our OCT system and used to measure non-scattering liquid phantoms and blood samples. The measured maximum sensitivity and roll-off rate over a range of image depths were 112 dB and ? 1.45 dB mm?1, respectively. The minimum axial resolution of the OCT system was 8.06 ?m at a depth of 2.4 mm. Quantitative and localized absorption spectra were recovered from the non-scattering liquid phantoms. In addition, the measured localized wavelength-dependent attenuation difference of oxygenated and deoxygenated blood was 4.6-fold.

  19. Application of wavelet analysis in optical coherence tomography for obscured pattern recognition

    International Nuclear Information System (INIS)

    Nowadays the optical coherent tomography (OCT) is one of the most perspective optical diagnostic modalities widely used for non-invasive imaging of the internal structure of various complex turbid media from a range of composite materials to biological tissues. OCT has been attracting a great amount of attention due to its effective capability rejecting multiple scattering. However, for highly scattered composite structures the multiple scattering still remains a factor limiting OCT to the quasi-ballistic regime. In order to enhance the OCT imaging capabilities and reduce the statistical noise associated with the multiple scattering the wavelet analysis has been applied. The wavelet analysis has been used to decompose the OCT images of printed stripes covered by a highly scattered and not transparent layer of white correction tape. The obtained results demonstrate a significant reduction of speckle noise background and enhancement of OCT images of the obscured patterns. This likely to be enabled extending the applicability of the combined OCT-wavelet decomposition analysis to investigate sensitive documents, historical artworks and valuable security papers

  20. Non-Destructive Inspection Methods for LEDs Using Real-Time Displaying Optical Coherence Tomography

    Directory of Open Access Journals (Sweden)

    Suhwan Kim

    2012-07-01

    Full Text Available In this study, we report the applicability of two different Optical Coherence Tomography (OCT technologies for inspecting Light Emitting Diode (LED structures. Sectional images of a LED were captured using a Spectral Domain OCT (SD-OCT system and a Swept Source OCT (SS-OCT system. Their center wavelengths are 850 and 1,310 nm, respectively. We acquired cross-sectional two dimensional (2D images of a normal LED and extracted sectional profiles to inspect possible wire disconnection that may be present in the LED manufacturing process. The SD-OCT and SS-OCT images were compared with each other in the same sample to study their advantages. The distribution of fluorescence material was observed more clearly with the SD-OCT of 850 nm wavelength, whereas the status of wire connection was clearer in the SS-OCT images with 1,310 nm wavelength. In addition, the volume of the fluorophore space was calculated from the OCT images. This is the first report that a nondestructive optical imaging modality such as OCT can be applied to finding screen defects in LED. We expect this method can improve the inspection efficacy over traditional inspection methods such as Charged Coupled Device (CCD camera or X-ray instruments.

  1. A physical model eye with 3D resolution test targets for optical coherence tomography

    Science.gov (United States)

    Hu, Zhixiong; Liu, Wenli; Hong, Baoyu; Hao, Bingtao; Wang, Lele; Li, Jiao

    2014-09-01

    Optical coherence tomography (OCT) has been widely employed as non-invasive 3D imaging diagnostic instrument, particularly in the field of ophthalmology. Although OCT has been approved for use in clinic in USA, Europe and Asia, international standardization of this technology is still in progress. Validation of OCT imaging capabilities is considered extremely important to ensure its effective use in clinical diagnoses. Phantom with appropriate test targets can assist evaluate and calibrate imaging performance of OCT at both installation and throughout lifetime of the instrument. In this paper, we design and fabricate a physical model eye with 3D resolution test targets to characterize OCT imaging performance. The model eye was fabricated with transparent resin to simulate realistic ophthalmic testing environment, and most key optical elements including cornea, lens and vitreous body were realized. The test targets which mimic USAF 1951 test chart were fabricated on the fundus of the model eye by 3D printing technology. Differing from traditional two dimensional USAF 1951 test chart, a group of patterns which have different thickness in depth were fabricated. By measuring the 3D test targets, axial resolution as well as lateral resolution of an OCT system can be evaluated at the same time with this model eye. To investigate this specialized model eye, it was measured by a scientific spectral domain OCT instrument and a clinical OCT system respectively. The results demonstrate that the model eye with 3D resolution test targets have the potential of qualitatively and quantitatively validating the performance of OCT systems.

  2. Use of an oxygen-carrying blood substitute to improve intravascular optical coherence tomography imaging

    Science.gov (United States)

    Hoang, Khiet C.; Edris, Ahmad; Su, Jianping; Mukai, David S.; Mahon, Sari; Petrov, Artiom D.; Kern, Morton; Ashan, Chowdhury; Chen, Zhongping; Tromberg, Bruce J.; Narula, Jagat; Brenner, Matthew

    2009-01-01

    Optical coherence tomography (OCT) is a catheter-based imaging technology with powerful resolution capable of identifying vulnerable plaques and guiding coronary intervention. However, a significant limitation of intravascular OCT imaging is its attenuation by blood. We propose that the use of an oxygen-carrying blood substitute could potentially optimize OCT image quality. Surgical isolation of the descending thoracic aorta of six rabbits is performed, followed by intravascular OCT imaging of the abdominal aorta. Perfluorodecalin (PFD) is oxygenated using a bubble-through technique with 100% oxygen. OCT imaging is performed and compared using three different flushing modalities: PFD; saline; and blood. OCT imaging of the rabbit abdominal aorta is successful in all of the subjects. In each of the six studied subjects, flushing with PFD consistently provides dramatically better imaging of the vessel wall tissue structures. OCT image quality is highly dependent on the ability of the flushing modality to remove blood from the imaging field. From this proof-of-concept study, we demonstrate that endovascular flushing with an oxygen-carrying blood substitute (PFD) is optically superior to saline flushing for intravascular imaging. PMID:19566321

  3. Cadaveric in-situ testing of optical coherence tomography system-based skull base surgery guidance

    Science.gov (United States)

    Sun, Cuiru; Khan, Osaama H.; Siegler, Peter; Jivraj, Jamil; Wong, Ronnie; Yang, Victor X. D.

    2015-03-01

    Optical Coherence Tomography (OCT) has extensive potential for producing clinical impact in the field of neurological diseases. A neurosurgical OCT hand-held forward viewing probe in Bayonet shape has been developed. In this study, we test the feasibility of integrating this imaging probe with modern navigation technology for guidance and monitoring of skull base surgery. Cadaver heads were used to simulate relevant surgical approaches for treatment of sellar, parasellar and skull base pathology. A high-resolution 3D CT scan was performed on the cadaver head to provide baseline data for navigation. The cadaver head was mounted on existing 3- or 4-point fixation systems. Tracking markers were attached to the OCT probe and the surgeon-probe-OCT interface was calibrated. 2D OCT images were shown in real time together with the optical tracking images to the surgeon during surgery. The intraoperative video and multimodality imaging data set, consisting of real time OCT images, OCT probe location registered to neurosurgical navigation were assessed. The integration of intraoperative OCT imaging with navigation technology provides the surgeon with updated image information, which is important to deal with tissue shifts and deformations during surgery. Preliminary results demonstrate that the clinical neurosurgical navigation system can provide the hand held OCT probe gross anatomical localization. The near-histological imaging resolution of intraoperative OCT can improve the identification of microstructural/morphology differences. The OCT imaging data, combined with the neurosurgical navigation tracking has the potential to improve image interpretation, precision and accuracy of the therapeutic procedure.

  4. Real-time processing for Fourier domain optical coherence tomography using a field programmable gate array

    Science.gov (United States)

    Ustun, Teoman E.; Iftimia, Nicusor V.; Ferguson, R. Daniel; Hammer, Daniel X.

    2008-11-01

    Real-time display of processed Fourier domain optical coherence tomography (FDOCT) images is important for applications that require instant feedback of image information, for example, systems developed for rapid screening or image-guided surgery. However, the computational requirements for high-speed FDOCT image processing usually exceeds the capabilities of most computers and therefore display rates rarely match acquisition rates for most devices. We have designed and developed an image processing system, including hardware based upon a field programmable gated array, firmware, and software that enables real-time display of processed images at rapid line rates. The system was designed to be extremely flexible and inserted in-line between any FDOCT detector and any Camera Link frame grabber. Two versions were developed for spectrometer-based and swept source-based FDOCT systems, the latter having an additional custom high-speed digitizer on the front end but using all the capabilities and features of the former. The system was tested in humans and monkeys using an adaptive optics retinal imager, in zebrafish using a dual-beam Doppler instrument, and in human tissue using a swept source microscope. A display frame rate of 27 fps for fully processed FDOCT images (1024 axial pixels×512 lateral A-scans) was achieved in the spectrometer-based systems.

  5. High-speed polarization sensitive optical coherence tomography for retinal diagnostics

    Science.gov (United States)

    Yin, Biwei; Wang, Bingqing; Vemishetty, Kalyanramu; Nagle, Jim; Liu, Shuang; Wang, Tianyi; Rylander, Henry G., III; Milner, Thomas E.

    2012-01-01

    We report design and construction of an FPGA-based high-speed swept-source polarization-sensitive optical coherence tomography (SS-PS-OCT) system for clinical retinal imaging. Clinical application of the SS-PS-OCT system is accurate measurement and display of thickness, phase retardation and birefringence maps of the retinal nerve fiber layer (RNFL) in human subjects for early detection of glaucoma. The FPGA-based SS-PS-OCT system provides three incident polarization states on the eye and uses a bulk-optic polarization sensitive balanced detection module to record two orthogonal interference fringe signals. Interference fringe signals and relative phase retardation between two orthogonal polarization states are used to obtain Stokes vectors of light returning from each RNFL depth. We implement a Levenberg-Marquardt algorithm on a Field Programmable Gate Array (FPGA) to compute accurate phase retardation and birefringence maps. For each retinal scan, a three-state Levenberg-Marquardt nonlinear algorithm is applied to 360 clusters each consisting of 100 A-scans to determine accurate maps of phase retardation and birefringence in less than 1 second after patient measurement allowing real-time clinical imaging-a speedup of more than 300 times over previous implementations. We report application of the FPGA-based SS-PS-OCT system for real-time clinical imaging of patients enrolled in a clinical study at the Eye Institute of Austin and Duke Eye Center.

  6. Real-time processing for Fourier domain optical coherence tomography using a field programmable gate array.

    Science.gov (United States)

    Ustun, Teoman E; Iftimia, Nicusor V; Ferguson, R Daniel; Hammer, Daniel X

    2008-11-01

    Real-time display of processed Fourier domain optical coherence tomography (FDOCT) images is important for applications that require instant feedback of image information, for example, systems developed for rapid screening or image-guided surgery. However, the computational requirements for high-speed FDOCT image processing usually exceeds the capabilities of most computers and therefore display rates rarely match acquisition rates for most devices. We have designed and developed an image processing system, including hardware based upon a field programmable gated array, firmware, and software that enables real-time display of processed images at rapid line rates. The system was designed to be extremely flexible and inserted in-line between any FDOCT detector and any Camera Link frame grabber. Two versions were developed for spectrometer-based and swept source-based FDOCT systems, the latter having an additional custom high-speed digitizer on the front end but using all the capabilities and features of the former. The system was tested in humans and monkeys using an adaptive optics retinal imager, in zebrafish using a dual-beam Doppler instrument, and in human tissue using a swept source microscope. A display frame rate of 27 fps for fully processed FDOCT images (1024 axial pixels x 512 lateral A-scans) was achieved in the spectrometer-based systems. PMID:19045902

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

    Science.gov (United States)

    Giacometti, Paolo; Diamond, Solomon G.

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

  8. Detection and analysis of multi-dimensional pulse wave based on optical coherence tomography

    Science.gov (United States)

    Shen, Yihui; Li, Zhifang; Li, Hui; Chen, Haiyu

    2014-11-01

    Pulse diagnosis is an important method of traditional Chinese medicine (TCM). Doctors diagnose the patients' physiological and pathological statuses through the palpation of radial artery for radial artery pulse information. Optical coherence tomography (OCT) is an useful tool for medical optical research. Current conventional diagnostic devices only function as a pressure sensor to detect the pulse wave - which can just partially reflect the doctors feelings and lost large amounts of useful information. In this paper, the microscopic changes of the surface skin above radial artery had been studied in the form of images based on OCT. The deformation of surface skin in a cardiac cycle which is caused by arterial pulse is detected by OCT. The patient's pulse wave is calculated through image processing. It is found that it is good consistent with the result conducted by pulse analyzer. The real-time patient's physiological and pathological statuses can be monitored. This research provides a kind of new method for pulse diagnosis of traditional Chinese medicine.

  9. 3D imaging of tomato seeds using frequency domain optical coherence tomography

    Science.gov (United States)

    Fan, Chuanmao; Yao, Gang

    2012-05-01

    A fast imaging system that can reveal internal sample structures is important for research and quality controls of seeds. Optical coherence tomography (OCT) is a non-invasive optical imaging technique that can acquire high speed, high resolution depth-resolved images in scattering samples. It has found numerous applications in studying various biological tissues and other materials in vivo. A few studies have reported the use of OCT in studying seed morphology. However, 3D imaging of internal seed structure has not been reported before. In this study, we used a frequency domain OCT system to image tomato seeds. The system has a central wavelength of 844nm with a 46.8 nm FWHM bandwidth. The requirement for depth scan was eliminated by using a Fourier domain implementation. The B-scan imaging speed was limited by the spectroscopic imaging CCD at 52 kHz. The calibrated system has a 6.7?m depth resolution and a 15.4?m lateral resolution. Our results show that major seed structures can be clearly visualized in OCT images.

  10. Diagnostic value of optical coherence tomography for intracranial pressure in idiopathic intracranial hypertension

    DEFF Research Database (Denmark)

    Skau, Maren; Yri, Hanne

    2013-01-01

    BACKGROUND: Idiopathic intracranial hypertension (IIH) is a condition of raised intracranial pressure (ICP) in the absence of space-occupying lesions or other known etiology. It primarily affects young obese females, and potentially causes permanent visual loss due to papilledema and secondary optic atrophy. The aim of this study was to evaluate the diagnostic value of optical coherence tomography (OCT) as a marker for CSF opening pressure in patients with idiopathic intracranial hypertension (IIH). METHODS: We conducted a case-control study of 20 newly diagnosed, 21 long-term IIH patients, and 20 healthy controls. Investigations included measurement of peripapillary retinal nerve fiber layer thickness (RNFLT) and total retinal thickness (RT), automated visual field testing, and measurement of CSF opening pressure. An OCT elevation diagram was developed as a new diagnostic tool. The diagnostic ability of OCT as a marker of increased ICP (> 25 cmH(2)O) was investigated using multiple regression and receiver operating characteristic (ROC) curves. RESULTS: OCT elevation diagrams showed that in 60 % of patients newly diagnosed with IIH and in 10 % of patients with long-term IIH, 50 % or more of the OCT scans (RT and RNFLT) were above normal. The percentage of abnormal OCT scans was significantly associated with increased ICP (p?

  11. Distinguish activations on sensorimotor cortex using high-resolution diffuse optical tomography

    Science.gov (United States)

    Zhao, Qing; Ji, Lijun; Shi, Feng; Jiang, Tianzi

    2007-05-01

    Diffuse optical tomography (DOT) is an appropriate tool for non-invasive exploration of human brain activation. The activation of sensorimotor cortex has been studied by several researchers since the first images of human brain were generated in 1995. However, high-quality images of sensorimotor cortex can not be obtained until the emerging of high-resolution DOT which uses a multi-centered geometry for arranging optical fibers. In this study, we did two experiments using our CW5 instrument (TechEn, USA). In the first experiment, the subject was asked to move his four fingers of right hand for 30 seconds, followed by 30 seconds of rest. Data collection lasted 420 seconds. In the second experiment, the subject was asked to tap his thumb against the other four fingers. Two conclusions can be reached from the experiments. Firstly, larger activated regions can be found on motor cortex in experiment 2 than in experiment 1. This indicates that high-resolution DOT can detect larger activated brain region when moving five fingers comparing to moving four fingers. Secondly, few activated regions can be found on sensory cortex in experiment 1, but it can be clearly found on sensory cortex in experiment 2. Up to our knowledge, it is the first time DOT has detected activated region on sensory cortex during motorial task.

  12. Laser tissue coagulation and concurrent optical coherence tomography through a double-clad fiber coupler.

    Science.gov (United States)

    Beaudette, Kathy; Baac, Hyoung Won; Madore, Wendy-Julie; Villiger, Martin; Godbout, Nicolas; Bouma, Brett E; Boudoux, Caroline

    2015-04-01

    Double-clad fiber (DCF) is herein used in conjunction with a double-clad fiber coupler (DCFC) to enable simultaneous and co-registered optical coherence tomography (OCT) and laser tissue coagulation. The DCF allows a single channel fiber-optic probe to be shared: i.e. the core propagating the OCT signal while the inner cladding delivers the coagulation laser light. We herein present a novel DCFC designed and built to combine both signals within a DCF (>90% of single-mode transmission; >65% multimode coupling). Potential OCT imaging degradation mechanisms are also investigated and solutions to mitigate them are presented. The combined DCFC-based system was used to induce coagulation of an ex vivo swine esophagus allowing a real-time assessment of thermal dynamic processes. We therefore demonstrate a DCFC-based system combining OCT imaging with laser coagulation through a single fiber, thus enabling both modalities to be performed simultaneously and in a co-registered manner. Such a system enables endoscopic image-guided laser marking of superficial epithelial tissues or laser thermal therapy of epithelial lesions in pathologies such as Barrett's esophagus. PMID:25909013

  13. Diffuse optical tomography enhanced by clustered sparsity for functional brain imaging.

    Science.gov (United States)

    Chen, Chen; Tian, Fenghua; Liu, Hanli; Huang, Junzhou

    2014-12-01

    Diffuse optical tomography (DOT) is a noninvasive technique which measures hemodynamic changes in the tissue with near infrared light, which has been increasingly used to study brain functions. Due to the nature of light propagation in the tissue, the reconstruction problem is severely ill-posed. For linearized DOT problems, sparsity regularization has achieved promising results over conventional Tikhonov regularization in recent experimental research. As extensions to standard sparsity, it is widely known that structured sparsity based methods are often superior in terms of reconstruction accuracy, when the data follows some structures. In this paper, we exploit the structured sparsity of diffuse optical images. Based on the functional specialization of the brain, it is observed that the in vivo absorption changes caused by a specific brain function would be clustered in certain region(s) and not randomly distributed. Thus, a new algorithm is proposed for this clustered sparsity reconstruction (CSR). Results of numerical simulations and phantom experiments have demonstrated the superiority of the proposed method over the state-of-the-art methods. An example from human in vivo measurements further confirmed the advantages of the proposed CSR method. PMID:25055380

  14. Use of an oxygen-carrying blood substitute to improve intravascular optical coherence tomography imaging.

    Science.gov (United States)

    Hoang, Khiet C; Edris, Ahmad; Su, Jianping; Mukai, David S; Mahon, Sari; Petrov, Artiom D; Kern, Morton; Ashan, Chowdhury; Chen, Zhongping; Tromberg, Bruce J; Narula, Jagat; Brenner, Matthew

    2009-01-01

    Optical coherence tomography (OCT) is a catheter-based imaging technology with powerful resolution capable of identifying vulnerable plaques and guiding coronary intervention. However, a significant limitation of intravascular OCT imaging is its attenuation by blood. We propose that the use of an oxygen-carrying blood substitute could potentially optimize OCT image quality. Surgical isolation of the descending thoracic aorta of six rabbits is performed, followed by intravascular OCT imaging of the abdominal aorta. Perfluorodecalin (PFD) is oxygenated using a bubble-through technique with 100% oxygen. OCT imaging is performed and compared using three different flushing modalities: PFD; saline; and blood. OCT imaging of the rabbit abdominal aorta is successful in all of the subjects. In each of the six studied subjects, flushing with PFD consistently provides dramatically better imaging of the vessel wall tissue structures. OCT image quality is highly dependent on the ability of the flushing modality to remove blood from the imaging field. From this proof-of-concept study, we demonstrate that endovascular flushing with an oxygen-carrying blood substitute (PFD) is optically superior to saline flushing for intravascular imaging. PMID:19566321

  15. Combining optical coherence tomography with acoustic radiation force for depth-dependent biomechanics of crystalline lens

    Science.gov (United States)

    Wang, Shang; Aglyamov, Salavat; Karpiouk, Andrei; Li, Jiasong; Emelianov, Stanislav; Manns, Fabrice; Larin, Kirill V.

    2014-03-01

    Noninvasively probing the biomechanical properties of crystalline lens has been challenging due to its unique features such as location inside the eye and being optically and ultrasonically transparent. Here we introduce a method of relying on the spectral analysis of the lens surface response to a mechanical stimulation for the depthdependent assessment of lens biomechanical properties. In this method, acoustic radiation force (ARF) is used to remotely induce the deformation on the surface of the crystalline lens, and a phase-sensitive optical coherence tomography (PhS-OCT) system, co-focused with ARF, utilized to monitor the localized temporal response of ARFinduced deformations on the lens surface. The dominant frequency from the amplitude spectra of the surface response is obtained as the indicator of the depthwise elasticity distribution. Pilot experiments were performed on tissue-mimicking layered phantoms and ex vivo porcine crystalline lens. Results indicate that the frequency response of the sample surface is contributed by the mechanical properties of layers located at different depths and the depthdependent elastic properties can be revealed from the amplitude spectrum. Further study will be focused on combining the experimental measurements with theoretical model and inverse numerical method for depth-resolved elastography of the crystalline lens.

  16. Broadband Fourier domain mode-locked laser for optical coherence tomography at 1060 nm

    DEFF Research Database (Denmark)

    Marschall, Sebastian; Klein, Thomas

    2012-01-01

    Optical coherence tomography (OCT) in the 1060nm range is interesting for in vivo imaging of the human posterior eye segment (retina, choroid, sclera) due to low absorption in water and deep penetration into the tissue. Rapidly tunable light sources, such as Fourier domain mode-locked (FDML) lasers, enable acquisition of densely sampled three-dimensional datasets covering a wide field of view. However, semiconductor optical amplifiers (SOAs)-the typical laser gain media for swept sources-for the 1060nm band could until recently only provide relatively low output power and bandwidth. We have implemented an FDML laser using a new SOA featuring broad gain bandwidth and high output power. The output spectrum coincides with the wavelength range of minimal water absorption, making the light source ideal for OCT imaging of the posterior eye segment. With a moderate SOA current (270 mA) we achieve up to 100nm total sweep range and 12 ?m depth resolution in air. By modulating the current, we can optimize the output spectrum and thereby improve the resolution to 9 ?m in air (~6.5 ?m in tissue). The average output power is higher than 20mW. Both sweep directions show similar performance; hence, both can be used for OCT imaging. This enables an A-scan rate of 350 kHz without buffering the light source output.

  17. Effect of fibrinogen on blood coagulation detected by optical coherence tomography

    Science.gov (United States)

    Xu, Xiangqun; Teng, Xiangshuai

    2015-05-01

    Our previous work demonstrated that an optical coherence tomography (OCT) technique and the parameter 1/e light penetration depth (d1/e) were able to characterize the whole blood coagulation process in contrast to existing optical tests that are performed on plasma samples. To evaluate the feasibility of the technique for quantifying the effect of fibrinogen (Fbg) on blood coagulation, a dynamic study of d1/e of blood in various Fbg concentrations was performed in static state. Two groups of blood samples of hematocrit (HCT) in 35, 45, and 55% were reconstituted of red blood cells with: 1) treated plasma with its intrinsic Fbg removed and commercial Fbg added (0–8?g?L?1) and 2) native plasma with commercial Fbg added (0–8?g?L?1). The results revealed a typical behavior due to coagulation induced by calcium ions and the clotting time is Fbg concentration-dependent. The clotting time was decreased by the increasing amount of Fbg in both groups. Besides, the blood of lower HCT with various levels of Fbg took shorter time to coagulate than that of higher HCT. Consequently, the OCT method is a useful and promising tool for the detection of blood-coagulation processes induced with different Fbg levels.

  18. A handheld optical fiber parallel acoustic delay line (PADL) probe for photoacoustic tomography

    Science.gov (United States)

    Cho, Young; Chang, Cheung-Chung; Jeon, Mansik; Kim, Chulhong; Wang, Lihong V.; Zou, Jun

    2014-03-01

    In current photoacoustic tomography (PAT), l-D or 2-D ultrasound arrays and multi-channel data acquisition (DAQ) electronics are used to detect the photoacoustic signals simultaneously for "real-time" image construction. However, as the number of transducer elements and DAQ channels increase, the construction and operation of the ultrasound receiving system will become complex and costly. This situation can be addressed by using parallel acoustic delay lines (PADLs) to create true time delays in multiple PA signal channels. The time-delayed PA signals will reach the ultrasound transducer at different times and therefore can be received by one single-element transducer without mixing with each other. In this paper, we report the development of the first miniaturized PADL probe suitable for handheld operations. Fusedsilica optical fibers with low acoustic attenuation were used to construct the 16 PADLs with specific time delays. The handheld probe structure was fabricated using precision laser-micromachining process to provide robust mechanical support and accurate alignment of the PADLs with minimal acoustic distortion and inter-channel coupling. The 16 optical-fiber PADLs were arranged to form one input port and two output ports. Photoacoustic imaging of a black-ink target embedded in an optically-scattering phantom was successfully conducted using the handheld PADL probe with two single-element transducers and two DAQ channels (equal to a channel reduction ratio of 8:1). Our results show that the PADL technique and the handheld probe could provide a promising solution for real-time PAT with significantly reduced complexity and cost of the ultrasound receiver system.

  19. Study of ionizing radiation effects in human costal cartilage by thermogravimetry and optical coherence tomography

    International Nuclear Information System (INIS)

    Tissue Banks around the world have stored human cartilages obtained from post mortem donors for use in several kinds of reconstructive surgeries. To ensure that such tissues are not contaminated, they have been sterilized with ionizing radiation. However, high doses of gamma radiation may cause undesirable changes in the tissues. In this work, we evaluated the possibility of use Optical Coherence Tomography (OCT) and Thermogravimetric Analysis (TGA) to identify possible structural modifications caused by both preservation methods of cartilage and gamma irradiation doses. Cartilages were obtained from cadaveric donors and were frozen at -70 deg C or preserved in glycerol. Irradiation was performed by 60Co source with doses of 15, 25 and 50 kGy. Our TGA results showed that glycerolized cartilages irradiated with different doses of radiation does not presented statistical differences when compared to the control group for the dehydration rate. However, the same was not observed for deep-frozen cartilages irradiated with 15 kGy. The results of OCT associated to total optical attenuation coefficient showed that doses of 15 kGy promote cross-link between collagen fibrils, corroborating the results obtained from TGA. Moreover, total optical attenuation coefficient values are proportional to stress at break of cartilages, what will be very useful in a near future to predict the quality of the allografts, without unnecessary loss of biological tissue, once OCT is a nondestructive technique. By PS-OCT images, we found that high doses of ionizing radiation does not promote sufficient impairments to promote complete loss of tissue birefringence. Thus, TGA and OCT are techniques that can be used for tissue banks to verify tissue quality before its transplant. (author)

  20. Optical Tomography of MMP Activity Allows a Sensitive Noninvasive Characterization of the Invasiveness and Angiogenesis of SCC Xenografts

    Directory of Open Access Journals (Sweden)

    Wa'el Al Rawashdeh

    2014-03-01

    Full Text Available For improved tumor staging and therapy control, imaging biomarkers are of great interest allowing a noninvasive characterization of invasiveness. In squamous epithelial skin and cervix lesions, transition to invasive stages is associated with enhanced matrix metalloproteinase (MMP activity, increased angiogenesis, and worsened prognosis. Thus, we investigated MMP activity as imaging biomarker of invasiveness and the potential of optical tomography in characterizing the angiogenic and invasive behavior of skin squamous cell carcinoma (SCC xenografts. MMP activity was measured in vivo in HaCaT-ras A-5RT3 tumors at different angiogenic and invasive stages (onset of angiogenesis, intermediate and highly angiogenic, invasive stage and after 1 week of sunitinib treatment by fluorescence molecular tomography–microcomputed tomography imaging using an activatable probe. Treatment response was additionally assessed morphologically by optical coherence tomography (OCT. In vivo MMP activity significantly differed between the groups, revealing highest levels in the highly angiogenic, invasive tumors that were confirmed by immunohistochemistry. At the onset of angiogenesis with lowest MMP activity, fibroblasts were detected in the MMP-positive areas, whereas macrophages were absent. Accumulation of both cell types occurred in both invasive groups, again to a significantly higher degree at the most invasive and angiogenic stage. Sunitinib treatment significantly reduced the MMP activity and accumulation of fibroblasts and macrophages and blocked tumor invasion that was additionally visualized by OCT. Human cervical SCCs also showed high MMP activity and a similar stromal composition as the HaCaT xenografts, whereas normal tissue was negative. This study strongly suggests MMP activity as imaging biomarker and demonstrates the high sensitivity of optical tomography in determining tumor invasiveness that can morphologically be supported by OCT.