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Sample records for saggital optical tomography

  1. Optical Coherence Tomography

    Andersen, Peter E.

    Optical coherence tomography (OCT) is a noninvasive imaging technique that provides real-time two- and three-dimensional images of scattering samples with micrometer resolution. Mapping the local reflectivity, OCT visualizes the morphology of the sample, in real time or at video rate. In addition......-rate imaging is feasible, which has enabled optical microangiography, i.e., visualization of retinal and chorodial blood flow. Such label-free optical microangiography might be feasible as an adjunct modality to fluorescence-based angiography. In this review, the fundamental principles of OCT imaging and its...

  2. Optical Coherence Tomography

    Mogensen, Mette; Themstrup, Lotte; Banzhaf, Christina; Marschall, Sebastian; Andersen, Peter E.; Jemec, Gregor B. E. J.

    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...

  3. Optical Tomography in Combustion

    Evseev, Vadim

    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 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...... 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...

  4. Amplified Dispersive Optical Tomography

    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.

  5. Optical coherency matrix tomography

    Kagalwala, Kumel H.; Kondakci, H. Esat; Abouraddy, Ayman F.; Saleh, Bahaa E. A.

    2015-10-01

    The coherence of an optical beam having multiple degrees of freedom (DoFs) is described by a coherency matrix G spanning these DoFs. This optical coherency matrix has not been measured in its entirety to dateeven in the simplest case of two binary DoFs where G is a 4??4 matrix. We establish a methodical yet versatile approachoptical coherency matrix tomographyfor reconstructing G that exploits the analogy between this problem in classical optics and that of tomographically reconstructing the density matrix associated with multipartite quantum states in quantum information science. Here G is reconstructed from a minimal set of linearly independent measurements, each a cascade of projective measurements for each DoF. We report the first experimental measurements of the 4??4 coherency matrix G associated with an electromagnetic beam in which polarization and a spatial DoF are relevant, ranging from the traditional two-point Youngs double slit to spatial parity and orbital angular momentum modes.

  6. [Optical coherence tomography].

    von Braunmühl, T

    2015-07-01

    Optical coherence tomography (OCT) was introduced in the 1990s in dermatology and is nowadays established as a noninvasive high-resolution technique for the in vivo evaluation of the skin. To date several studies have been successfully demonstrated the application of OCT for various dermatological questions. The main indication for OCT in the daily practice is the noninvasive diagnosis of nonmelanoma skin cancer such as actinic keratosis and basal cell carcinoma. OCT has also been shown to be a valuable tool in treatment monitoring and evaluation of therapeutic success of noninvasive treatment strategies like topical immune modulators or photodynamic treatment. Other potential applications for OCT include inflammatory diseases, microbial or parasitic infestations of the skin, e.g. scabies mites or onychomycosis. In recent years high-definition OCT devices have been developed that can potentially be used for the evaluation of melanocytic lesions and, due to the higher resolution, for the visualization of intrafollicular demodex mites. Furthermore different commercially available devices offer-in addition to the cross-sectional images-a fast-generated horizontal (en face) imaging mode. With respect to resolution and penetration depth the OCT technique is taking a middle position in comparison to other noninvasive imaging devices in dermatology such as sonography and reflectance confocal microscopy. PMID:25809459

  7. Second harmonic optical coherence tomography

    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.

  8. Hyperspectral optical diffraction tomography

    Jung, JaeHwang; Kim, Kyoohyun; Yoon, Jonghee; Park, YongKeun

    2016-02-01

    Here, we present a novel microscopic technique for measuring wavelength-dependent three-dimensional (3-D) distributions of the refractive indices (RIs) of microscopic samples in the visible wavelengths. Employing 3-D quantitative phase microscopy techniques with a wavelength-swept source, 3-D RI tomograms were obtained in the range of 450 - 700 nm with a spectral resolution of a few nanometers. The capability of the technique was demonstrated by measuring the hyperspectral 3-D RI tomograms of polystyrene beads, human red blood cells, and hepatocytes. The results demonstrate the potential for label-free molecular specific 3-D tomography of biological samples.

  9. Hyperspectral optical diffraction tomography

    Jung, JaeHwang; Yoon, Jonghee; Park, YongKeun

    2015-01-01

    Here, we present a novel microscopic technique for measuring wavelength-dependent three-dimensional (3-D) distributions of the refractive indices (RIs) of microscopic samples in the visible wavelengths. Employing 3-D quantitative phase microscopy techniques with a wavelength-swept source, 3-D RI tomograms were obtained in the range of 450 - 700 nm with a spectral resolution of a few nanometers. The capability of the technique was demonstrated by measuring the hyperspectral 3-D RI tomograms of polystyrene beads, human red blood cells, and hepatocytes. The results demonstrate the potential for label-free molecular specific 3-D tomography of biological samples.

  10. Optical Coherence Tomography: Advanced Modeling

    Andersen, Peter E.; Thrane, Lars; Yura, Harold T.; Tycho, Andreas; Jørgensen, Thomas Martini

    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...... discussed. Finally, the Wigner phase-space distribution function is derived in a closed-form solution, which may have applications in OCT....

  11. Optical Coherence Tomography

    Mogensen, Mette; Themstrup, Lotte; Banzhaf, Christina; Marschall, Sebastian; Andersen, Peter E.; Jemec, Gregor B. E. J.

    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...... 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...

  12. Retinal Optical Coherence Tomography Imaging

    Drexler, Wolfgang; Fujimoto, James G.

    The eye is essentially transparent, transmitting light with only minimal optical attenuation and scattering providing easy optical access to the anterior segment as well as the retina. For this reason, ophthalmic and especially retinal imaging has been not only the first but also most successful clinical application for optical coherence tomography (OCT). This chapter focuses on the development of OCT technology for retinal imaging. OCT has significantly improved the potential for early diagnosis, understanding of retinal disease pathogenesis, as well as monitoring disease progression and response to therapy. Development of ultrabroad bandwidth light sources and high-speed detection techniques has enabled significant improvements in ophthalmic OCT imaging performance, demonstrating the potential of three-dimensional, ultrahigh-resolution OCT (UHR OCT) to perform noninvasive optical biopsy of the living human retina, i.e., the in vivo visualization of microstructural, intraretinal morphology in situ approaching the resolution of conventional histopathology. Significant improvements in axial resolution and speed not only enable three-dimensional rendering of retinal volumes but also high-definition, two-dimensional tomograms, topographic thickness maps of all major intraretinal layers, as well as volumetric quantification of pathologic intraretinal changes. These advances in OCT technology have also been successfully applied in several animal models of retinal pathologies. The development of light sources emitting at alternative wavelengths, e.g., around #1,060 nm, not only enabled three-dimensional OCT imaging with enhanced choroidal visualization but also improved OCT performance in cataract patients due to reduced scattering losses in this wavelength region. Adaptive optics using deformable mirror technology, with unique high stroke to correct higher-order ocular aberrations, with specially designed optics to compensate chromatic aberration of the human eye, in combination with three-dimensional UHR OCT, recently enabled in vivo cellular resolution retinal imaging.

  13. High-definition optical coherence tomography

    Boone, Marc; Norrenberg, Sarah; Jemec, Gregor; Del Marmol, Vronique

    2013-01-01

    High-definition optical coherence tomography (HD-OCT) is a non-invasive technique for morphological investigation of tissue with cellular resolution filling the imaging gap between reflectance confocal microscopy and conventional optical coherence tomography. The aim of this study is first to...

  14. Imaging granulomatous lesions with optical coherence tomography

    Banzhaf, Christina; Jemec, Gregor B E

    2012-01-01

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

  15. In Vivo Diffuse Optical Tomography and Fluorescence Molecular Tomography

    Li, Mingze; Zhang, Yonghong; BAI, JING

    2010-01-01

    Diffuse optical tomography (DOT) and fluorescence molecular tomography (FMT) are two attractive imaging techniques for in vivo physiological and psychological research. They have distinct advantages such as non-invasiveness, non-ionizing radiation, high sensitivity and longitudinal monitoring. This paper reviews the key components of DOT and FMT. Light propagation model, mathematical reconstruction algorithm, imaging instrumentation and medical applications are included. Future challenges and...

  16. Optical Coherence Tomography in Glaucoma

    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.

  17. Fast algorithms for hyperspectral Diffuse Optical Tomography

    Saibaba, Arvind K.; Kilmer, Misha; Miller, Eric; Fantini, Sergio

    2014-01-01

    The image reconstruction of chromophore concentrations using Diffuse Optical Tomography (DOT) data can be described mathematically as an ill-posed inverse problem. Recent work has shown that the use of hyperspectral DOT data, as opposed to data sets comprising of a single or, at most, a dozen wavelengths, has the potential for improving the quality of the reconstructions. The use of hyperspectral diffuse optical data in the formulation and solution of the inverse problem poses a significant c...

  18. Reconstructions in ultrasound modulated optical tomography

    Allmaras, Moritz

    2011-01-01

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

  19. Optical coherence tomography: Technique and applications

    Thomsen, Jakob Borup; Sander, Birgit; Mogensen, Mette; Thrane, Lars; Jørgensen, Thomas Martini; Jemec, Gregor B.E.; Andersen, Peter E.

    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...... 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....

  20. Dermascope guided multiple reference optical coherence tomography

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

    2014-01-01

    In this paper, we report the feasibility of integrating a novel low cost optical coherence tomography (OCT) system with a dermascope for point-of-care applications. The proposed OCT system is based on an enhanced time-domain optical coherence tomographic system, called multiple reference OCT (MR-OCT), which uses a single miniature voice coil actuator and a partial mirror for extending the axial scan range. The system can simultaneously register both the superficial dermascope image and the de...

  1. Optical coherence tomography. Development, principles, applications

    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.)

  2. Optical coherence tomography in conjunction with bronchoscopy

    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)

  3. Computed tomography in optic neuritis

    In two patients with optic neuritis, CT scans showed common features which were helpful in diagnosis. These consisted of an enlargement of the optic nerve and an increased density of the optic nerve after contrast infusion. A 49-year-old man was admitted with a two-week duration of pain and a progressive visual loss in his right eye. On admission, an enlarged central scotoma was noted, and only a flashlight was perceived at the periphery in the right eye. The right optic disc was swollen with perivascular bleeding. Plain skull radiographs and orbital tomographs were normal. An orbital CT scan, however, revealed an enlargement of the right optic nerve, the density of which was increased after the infusion of a contrast medium. After steroid therapy, the CT scan showed a normal optic nerve following improvement in the vision of the right eye. A 44-year-old man was referred to this hospital because of a visual loss in his right eye which had been noted one month before. The right eye, with a central scotoma, had only visual acuity enough to perceive hand motion. The right pupil responded poorly to light. The right optic disc was hyperemic. Plain skull radiographs were normal. The orbital CT scan, however, showed an enlargement of the right optic nerve and exhibited contrast enhancement. Steroid therapy resulted in an improvement of the visual disturbance, and a follow-up CT scan showed normal. Two months later, though, the visual acuity had decreased and a visual field defect was noted in his left eye. The orbital CT scan revealed an enlargement of the left optic nerve. The administration of steroid again improved the visual field defect in the left eye, and the CT scan again showed normal. (author)

  4. Whole field reflectance optical tomography

    Carbone, Nicols A.; Garca, Hctor A.; di Rocco, Hctor O.; Iriarte, Daniela I.; Pomarico, Juan A.; Ranea Sandoval, Hctor F.

    2011-08-01

    Optical imaging through highly scattering media such as biological tissues is a topic of intense research, especially for biomedical applications. Diverse optical systems are currently under study and development for displaying the functional imaging of the brain and for the detection of breast tumors. From the theoretical point of view, a suitable description of light propagation in tissues involves the Radiative Transfer Equation, which considers the energetic aspects of light propagation. However, this equation cannot be solved analytically in a closed form and the Diffusion Approximation is normally used. Experimentally it is possible to use Transmission or Reflection geometries and Time Resolved, Frequency Modulated or CW sources. Each configuration has specific advantages and drawbacks, depending on the desired application. In the present contribution, we investigate the reflected light images registered by a CCD camera when scattering and absorbing inhomogeneities are located at different depths inside turbid media. This configuration is of particular interest for the detection and optical characterization of changes in blood flow in organs, as well as for the detection and characterization of inclusions in those cases for which the transmission slab geometry is not well suited. Images are properly normalized to the background intensity and allow analyzing relative large areas (typically 5 5 cm2) of the tissue. We tested the proposal using Numerical Monte Carlo simulations implemented in a Graphic Processing Unit (Video accelerating Card). Calculations are thus several orders of magnitude faster than those run in CPU. Experimental results in phantoms are also given.

  5. Optical Coherence Tomography for Material Characterization

    Liu, P.

    2014-01-01

    Optical coherence tomography (OCT) is a non-invasive, contactless and high resolution imaging method, which allows the reconstruction of two or three dimensional depth-resolved images in turbid media. In the past 20 years, OCT has been extensively developed in the field of biomedical diagnostics, while OCT in the non-destructive testing (NDT) field is lagging far behind. The aim of this thesis is to use OCT as a novel NDT technique for material structure characterization and damage detection....

  6. Turbidity Measurement Using An Optical Tomography System

    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...

  7. Optical coherence tomography findings of quinine poisoning

    John Christoforidis

    2011-01-01

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

  8. Diffuse optics for tissue monitoring and tomography

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

  9. ROLE OF OPTICAL COHERENCE TOMOGRAPHY IN CENTRAL SEROUS CHORIORETINOPATHY

    Junaid Salam; Parvez Ahmad; Andleeb; Suraya

    2015-01-01

    PURPOSE: To study the role of optical coherence tomography in central serous chorioretinopathy. MATERIAL AND METHODS: A total of 48 eyes of 48 patients with a clinical diagnosis of central serous chorioretinopathy were eval uated with spectral domain optical coherence tomography. After detailed ocular examination, followed by fundus fluorescein angiography, optical coherence tomography was performed and various anatomic features were noted. RESULTS: Out of 48 ...

  10. Advanced modelling of optical coherence tomography systems

    Andersen, Peter E.; Thrane, L.; Yura, H.T.; Tycho, A.; Jørgensen, T.M.; Frosz, M.H.

    2004-01-01

    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 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...

  11. Optical homodyne tomography with polynomial series expansion

    Benichi, Hugo; Furusawa, Akira [Department of Applied Physics, University of Tokyo, Tokyo (Japan)

    2011-09-15

    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.

  12. MEMS-Based Endoscopic Optical Coherence Tomography

    Jingjing Sun; Huikai Xie

    2011-01-01

    Early cancer detection has been playing an important role in reducing cancer mortality. Optical coherence tomography (OCT), due to its micron-scale resolution, has the ability to detect cancerous tissues at their early stages. For internal organs, endoscopic probes are needed as the penetration depth of OCT is about 1–3 mm. MEMS technology has the advantages of fast speed, small size, and low cost, and it has been widely used as the scanning engine in endoscopic OCT probes. Research results h...

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

    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.

  14. Optical Coherence Tomography Velocimetry with Complex Fluids

    Malm, A.; Waigh, T. A.; Jaradat, S.; Tomlin, R.

    2015-04-01

    We present recent results obtained with an Optical Coherence Tomography Velocimetry technique. An optical interferometer measures the velocity of a sheared fluid at specific depths of the sample using the coherence length of the light source. The technique allows the dynamics of 3 pico liter volumes to be probed inside opaque complex fluids. In a study of opaque starch suspensions, classical bulk rheology experiments show non-linear shear thickening, whereas observations of the velocity profiles as a function of distance across the gap show Newtonian behavior. The ability of the technique to measure velocity fluctuations is also discussed for the case of polyacrylamide samples which were observed to display shear banding behavior. A relationship between the viscoelasticity of the sample and the size of the apparent fluctuations is observed.

  15. Turbidity Measurement Using An Optical Tomography System

    Sallehuddin Bin Ibrahim

    2013-10-01

    Full Text Available 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 transmitters and photodiodes as the receivers where the projections of the sensors are designed in fan beam mode. The system was tested using a vertical flow pipe. The Independent Component Analysis (ICA method was used to display the concentration profile. Results obtained proved that the technique can provide the concentration profile representing the turbidity level of water.

  16. Optical coherence tomography - principles and applications

    Fercher, A. F.; Drexler, W.; Hitzenberger, C. K.; Lasser, T.

    2003-02-01

    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 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.

  17. Optical coherence tomography - principles and applications

    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 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

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

    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.

  19. Optical coherence tomography technology and applications

    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...

  20. Optical characterization of contrast agents for optical coherence tomography

    Lee, Tin-Man; Toublan, Farah J.; Oldenburg, Amy; Sitafalwalla, Shoeb; Luo, Wei; Marks, Daniel L.; Suslick, Kenneth S.; Boppart, Stephen A.

    2003-07-01

    The use of contrast agents in almost every imaging modality has been known to enhance the sensitivity of detection and improve diagnostic capabilities by site-specifically labeling tissues or cells of interest. The imaging capabilities of Optical Coherence Tomography (OCT) need to be improved in order to detect early neoplastic changes in medicine and tumor biology. We introduce and characterize the optical properties of several types of optical contrast agents in OCT, namely encapsulating microspheres that incorporate materials including melanin, gold, and carbon. Micron-sized microspheres have been fabricated by state-of-the-art sonicating and ultrasound technology. The optical properties of optical contrast agents have been characterized according to their scattering and absorption coefficients and lifetimes using OCT and the oblique incidence reflectometry method. Finally, we demonstrate the use of these optical contrast agents in in vitro mice liver and analyze the contrast improvement from the OCT images. These optical contrast agents have the potential to improve the detection of in vivo pathologies in the future.

  1. High-definition optical coherence tomography imaging of melanocytic lesions

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

    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...

  2. Characterisation of optically cleared paper by optical coherence tomography

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

  3. An Optical Tomography System Using a Digital Signal Processor

    Mohd Hafiz Fazalul Rahiman; Chiam Kok Thiam; Ruzairi Abdul Rahim

    2008-01-01

    The use of a personal computer together with a Data Acquisition System (DAQ) as the processing tool in optical tomography systems has been the norm ever since the beginning of process tomography. However, advancements in silicon fabrication technology allow nowadays the fabrication of powerful Digital Signal Processors (DSP) at a reasonable cost. This allows this technology to be used in an optical tomography system since data acquisition and processing can be performed within the DSP. Thus, ...

  4. Optical tomography of the aurora and EISCAT

    H. U. Frey

    Full Text Available Tomographic reconstruction of the three-dimensional auroral arc emission is used to obtain vertical and horizontal distributions of the optical auroral emission. Under the given experimental conditions with a very limited angular range and a small number of observers, algebraic reconstruction methods generally yield better results than transform techniques. Different algebraic reconstruction methods are tested with an auroral arc model and the best results are obtained with an iterative least-square method adapted from emission-computed tomography. The observation geometry used during a campaign in Norway in 1995 is tested with the arc model and root-mean-square errors, to be expected under the given geometrical conditions, are calculated. Although optimum geometry was not used, root-mean-square errors of less than 2% for the images and of the order of 30% for the distribution could be obtained. The method is applied to images from real observations. The correspondence of original pictures and projections of the reconstructed volume is discussed, and emission profiles along magnetic field lines through the three-dimensionally reconstructed arc are calibrated into electron density profiles with additional EISCAT measurements. Including a background profile and the temporal changes of the electron density due to recombination, good agreement can be obtained between measured profiles and the time-sequence of calculated profiles. These profiles are used to estimate the conductivity distribution in the vicinity of the EISCAT site. While the radar can only probe the ionosphere along the radar beam, the three-dimensional tomography enables conductivity estimates in a large area around the radar site.

    Key words. Tomography · Aurora · EISCAT · Ionosphere · Conductivity

  5. Measuring the optical characteristics of medulloblastoma with optical coherence tomography.

    Vuong, Barry; Skowron, Patryk; Kiehl, Tim-Rasmus; Kyan, Matthew; Garzia, Livia; Sun, Cuiru; Taylor, Michael D; Yang, Victor X D

    2015-04-01

    Medulloblastoma is the most common malignant pediatric brain tumor. Standard treatment consists of surgical resection, followed by radiation and high-dose chemotherapy. Despite these efforts, recurrence is common, leading to reduced patient survival. Even with successful treatment, there are often severe long-term neurologic impacts on the developing nervous system. We present two quantitative techniques that use a high-resolution optical imaging modality: optical coherence tomography (OCT) to measure refractive index, and the optical attenuation coefficient. To the best of our knowledge, this study is the first to demonstrate OCT analysis of medulloblastoma. Refractive index and optical attenuation coefficient were able to differentiate between normal brain tissue and medulloblastoma in mouse models. More specifically, optical attenuation coefficient imaging of normal cerebellum displayed layers of grey matter and white matter, which were indistinguishable in the structural OCT image. The morphology of the tumor was distinct in the optical attenuation coefficient imaging. These inherent properties may be useful during neurosurgical intervention to better delineate tumor boundaries and minimize resection of normal tissue. PMID:25909030

  6. Diffuse Optical Tomography for Brain Imaging: Theory

    Yuan, Zhen; Jiang, Huabei

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

  7. Nanoparticles for enhanced contrast optical coherence tomography

    Maule, César D.; Quaresma, Pedro; Carvalho, Patrícia A.; Jorge, Pedro; Pereira, Eulália; Rosa, Carla C.

    2008-09-01

    Recently the area of bioimaging has benefited from new types of image enhancing agents such as quantum dots, carbon nanotubes and other nanoparticles. Cellular or even molecular level resolution has been achieved with different techniques during these last years (i.a. Fluorescence microscopy, PET/CT scan, AFM). Optical Coherence Tomography (OCT) as an imaging technique should also profit from newly developed probes. In this work we explored the tunable properties of different types of nanoparticles as contrast enhancers in OCT applications. We mainly studied the development and characteristics of metallic nanoparticles with tunable properties: gold nanoshells made of a silica core coated with a gold shell. Nanoshell and nanoparticles processing techniques are discussed, as well as their optimization for designing particles with specific absorption and scattering characteristics, and its use in OCT imaging.

  8. Optical Coherence Tomography for Tracking Canvas Deformation

    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.

  9. EDITORIAL: Optical tomography and digital holography

    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 application areas within the field of engineering. The application of digital holography to 3D fluid flow measurement is addressed by several authors. Salah et al demonstrate the simplicity of digital holography with an in-line multiple exposure holographic system using a low-cost laser diode. Soria and Atkinson discuss limitations of low NA holography in fluid velocimetry and demonstrate the potential of a multiple camera, in-line technique which they call Tomographic Digital Holographic Particle Image Velocimetry (Tomo-HPIV). Problems caused by the twin images (real and virtual) of in-line HPIV are described by Ooms et al. It is shown how sign ambiguity can be eliminated and bias errors suppressed by the application of a suitable threshold in piecewise correlation of the reconstructed field. Denis et al explain the problem of twin image removal as a deconvolution process and compare suppression algorithms based on wavelet decomposition. This process can be considered as an inverse problem and the benefits of this approach are discussed with reference to particulate holograms by Gire et al. Of course, the twin image problem can be solved by off-axis holographic geometries which, in effect, add a carrier modulation. Arroyo presents a comparison of carrier modulation strategies that have been presented in the literature and shows circumstances in which the information in each of the real and virtual images can be separated when the sensor resolution is less than that required by the NA of the objective. State-of-the-art digital holographic microscopy (DHM) is presented by Kühn et al. This paper uses an off-axis geometry that simultaneously records images at two wavelengths. The microscope allows the surface profile to be measured from a single recording and sub-nanometre axial resolution is demonstrated. Another interesting application of DHM is addressed by Grilli et al. They report a transmission set-up to investigate poling in a lithium niobate crystal. Developments in the field of optical tomography are covered by the majority of the papers in this issue. The paper by Debailleul et al shows the differences between images reconstructed from a single holographic recording and those synthesized from a series of holograms made with different plane wave illumination. This is optical diffraction tomography (ODT), the original method discussed by Wolf that is characterized by large NA and monochromatic illumination. An alternative strategy is to synthesize the image from holograms made at several wavelengths with low NA optics. This can be done either by sweeping the source or detector response or the reference path in a white light interferometer. These methods are called spectral domain and temporal domain optical coherence tomography (SD-ODT and TD-OCT) respectively. SD-OCT is illustrated in the paper by Potcoava and Kim for biomedical applications. SD- and TD-OCT are compared with confocal microscopy in the paper by Stifter et al. The huge potential of OCT as a diagnostic in polymer and composite materials is apparent from this work. There are clearly many different ways to implement optical tomography, and several established techniques, such as scanning white light interferometry (SWLI) and confocal microscopy, can be considered to be tomographic processes. We present two papers in this issue. The first attempts to bring together the topics of holography, microscopy and tomography within the framework of linear systems theory. It is shown that the images (or interferograms) produced by these instruments can be considered as estimates of refractive index contrast that are obtained using a linear inversion of the scattered field data. It is noted, however, that this is only strictly correct for the case of weak scattering and this is only a crude approximation for many cases of practical interest. The second paper that we present illustrates this for the case of mono-disperse particles in air. Here the number density of the particles is such that multiple scattering is prevalent; however, a priori knowledge of particle size and refractive index allows individual particles to be located accurately. In general, reconstruction can be thought of as a nonlinear optimization process that is used to discover the object which best explains the measured field and is consistent with a priori information. As Gire et al point out in their article, a priori knowledge can also be used to overcome the Nyquist sampling criteria. Although some caution should be exercised (for example, it is not usually possible to decide whether a given solution is unique), it is interesting to note that despite the disparity in resolution, digital holography and computer technology might yet create 3D images of greater clarity than the best optical holograms. References [1] Schnars U and Jueptner W 2005 Digital Holography (Berlin: Springer) ISBN: 978 3 540 21934 7 [2] Gabor D 1948 A new microscopic principle Nature 161 777-8 [3] Bjelkhagen H I 1993 Silver-Halide Recording Materials (Berlin: Springer) ISBN 3 540 58619 9 [4] Leendertz J A 1970 Interferometric displacement measurement on scattering surfaces utilizing speckle effect J. Phys. E: Sci. Instrum. 3 214-8 [5] Marquet P, Rappaz B, Magistretti P J, Cuche E, Emery Y, Colomb T and Depeursinge C 2005 Digital holographic microscopy: a noninvasive contrast imaging technique allowing quantitative visualization of living cells with subwavelength axial accuracy Opt. Lett. 30 468-70 [6] Wolf E 1969 Three-dimensional structure determination of semi-transparent objects from holographic data Opt. Commun. 1 153-6 [7] Dandliker R and Weiss K 1970 Reconstruction of the three-dimensional refractive index from scattered waves Opt. Commun. 1 323-8 [8] Coupland J and Lobera J 2007 International Workshop on Digital Holographic Reconstruction and Optical Tomography for Engineering Applications ISBN 978 0 947974 56 5

  10. Intraoperative spectral domain optical coherence tomography for vitreoretinal surgery

    Tao, Yuankai K.; Ehlers, Justis P.; 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...

  11. Early results of the posterior saggital anorectoplasty in the treatment of anorectal malformations in Nigerian children

    Sowande O

    2006-01-01

    Full Text Available CONTEXT: The ultimate goal of reconstruction in anorectal malformations (ARM in children, is to create a functional and anatomically aesthetic neoanus. AIMS: To document our experience with the technique of PSARP in ARM and the immediate anatomical and functional outcome SETTINGS AND DESIGN: A retrospective study 39 patients with high and intermediate ARM, managed by the posterior saggital approach, at the Obafemi Awolowo University Teaching Hospital in Ile Ife, Nigeria MATERIALS AND METHODS: Patient′s bio-data were collected, as well as, the presentation, investigations, associated malformations, complications, average bowel opening per day and follow up. RESULTS: There were 17 males and 22 females (male: female ratio 1: 1.3. Twenty-three patients (59% and 15 patients (38.5%, had intermediate and high malformations respectively, while 1(2.5% had cloaca malformation. The mean age at presentation was 13.9±30.1 month (range 2 day to 15 years, while the mean age at PSARP was 21.6±29.9 months (range 2.5 days to 15 years. 3(7.6% patients required laparotomy to mobilize the rectal pouch from the abdomen. Mucosal prolapse was the most common significant postoperative problem, occurring in 4(10.3% patients. The average bowel motion was 3 times daily (range 1 to 8 times per day. CONCLUSIONS: The PSARP is a useful procedure for the correction of ARM, in children in developing countries, even in the absence of muscle stimulators. The immediate anatomical outcome is satisfactory, but functional results are difficult to access because of poor follow up.

  12. Optical coherence tomography used for internal biometrics

    Chang, Shoude; Sherif, Sherif; Mao, Youxin; Flueraru, Costel

    2007-06-01

    Traditional biometric technologies used for security and person identification essentially deal with fingerprints, hand geometry and face images. However, because all these technologies use external features of human body, they can be easily fooled and tampered with by distorting, modifying or counterfeiting these features. Nowadays, internal biometrics which detects the internal ID features of an object is becoming increasingly important. Being capable of exploring under-skin structure, optical coherence tomography (OCT) system can be used as a powerful tool for internal biometrics. We have applied fiber-optic and full-field OCT systems to detect the multiple-layer 2D images and 3D profile of the fingerprints, which eventually result in a higher discrimination than the traditional 2D recognition methods. More importantly, the OCT based fingerprint recognition has the ability to easily distinguish artificial fingerprint dummies by analyzing the extracted layered surfaces. Experiments show that our OCT systems successfully detected the dummy, which was made of plasticene and was used to bypass the commercially available fingerprint scanning system with a false accept rate (FAR) of 100%.

  13. Characterization of airborne transducers by optical tomography

    Bou Matar O; Pizarro; Certon; Remenieras; Patat

    2000-03-01

    This paper describes the application of an acousto-optic method to the measurement of airborne ultrasound. The method consists of a heterodyne interferometric probing of the pressure emitted by the transducer combined with a tomographic algorithm. The heterodyne interferometer measures the optical phase shift of the probe laser beam, proportional to the acoustic pressure integrated along the light path. A number of projections of the sound field, e.g. a set of ray integrals obtained along parallel paths, are made in moving the transducer to be tested. The main advantage of the method is its very high sensitivity in air (2 x 10(-4) Pa Hz-1/2), combined with a large bandwidth. Using the same principle as X-ray tomography the ultrasonic pressure in a plane perpendicular to the transducer axis can be reconstructed. Several ultrasonic fields emitted by wide-band home made electrostatic transducers, with operating frequencies between 200 and 700 kHz, have been measured. The sensitivities compared favorably with those of commercial airborne transducers. PMID:10829772

  14. Optical coherence tomography for endodontic imaging

    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.

  15. Optical Magnetic Induction Tomography of the Heart

    Marmugi, Luca; Renzoni, Ferruccio

    2016-04-01

    Atrial Fibrillation (AF) affects a significant fraction of the ageing population, causing a high level of morbidity and mortality. Despite its significance, the causes of AF are still not uniquely identified. This, combined with the lack of precise diagnostic and guiding tools, makes the clinical treatment of AF sub-optimal. We identify magnetic induction tomography as the most promising technique for the investigation of the causes of fibrillation and for its clinical practice. We therefore propose a novel optical instrument based on optical atomic magnetometers, fulfilling the requirements for diagnostic mapping of the heart’s conductivity. The feasibility of the device is here discussed in view of the final application. Thanks to the potential of atomic magnetometers for miniaturisation and extreme sensitivity at room temperature, a new generation of compact and non-invasive diagnostic instrumentation, with both bedside and intra-operative operation capability, is envisioned. Possible scenarios both in clinical practice and biomedical research are then discussed. The flexibility of the system makes it promising also for application in other fields, such as neurology and oncology.

  16. Functional optical coherence tomography: principles and progress

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

    2015-05-01

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

  17. Optical coherence tomography of the eye

    Hee, Michael Richard

    1997-10-01

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

  18. Motion contrast using optical coherence tomography

    Fingler, Jeffrey Paul

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

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

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

  20. 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...

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

    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...

  2. Polarization sensitive optical coherence tomography detection method

    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.

  3. Spatially varying detectability for optical tomography

    Pineda, Angel R.; Barrett, Harrison H.; Arridge, Simon R.

    2000-04-01

    We apply task-based assessment of image quality to optical tomography imaging systems. In particular, we studied the task of detecting a signal, specified as a change in scattering and absorption coefficients, when its shape and location were known. The detectability was quantified using the optimal linear (Hotelling) observer. The non-linearity of the problem was no impediment in computing the Hotelling observer using a hybrid approach that combines knowledge of the measurement statistics with sampling to account for anatomical variation. We compared the observer performance on the raw data in uniform and structured backgrounds for several data and signal types. Two of the data types studied were the total number of photons (total counts) collected for each source-detector pair and their respective mean time of arrival. Results show that the spatial variation of detectability was different for the total counts than for the mean time. The performance of the total counts and its relative performance to the mean time varied significantly with both signal type and background variations.

  4. Quantitative contrast-enhanced optical coherence tomography

    We have developed a model to accurately quantify the signals produced by exogenous scattering agents used for contrast-enhanced Optical Coherence Tomography (OCT). This model predicts distinct concentration-dependent signal trends that arise from the underlying physics of OCT detection. Accordingly, we show that real scattering particles can be described as simplified ideal scatterers with modified scattering intensity and concentration. The relation between OCT signal and particle concentration is approximately linear at concentrations lower than 0.8 particle per imaging voxel. However, at higher concentrations, interference effects cause signal to increase with a square root dependence on the number of particles within a voxel. Finally, high particle concentrations cause enough light attenuation to saturate the detected signal. Predictions were validated by comparison with measured OCT signals from gold nanorods (GNRs) prepared in water at concentrations ranging over five orders of magnitude (50 fM to 5 nM). In addition, we validated that our model accurately predicts the signal responses of GNRs in highly heterogeneous scattering environments including whole blood and living animals. By enabling particle quantification, this work provides a valuable tool for current and future contrast-enhanced in vivo OCT studies. More generally, the model described herein may inform the interpretation of detected signals in modalities that rely on coherence-based detection or are susceptible to interference effects

  5. Quantitative contrast-enhanced optical coherence tomography

    Winetraub, Yonatan; SoRelle, Elliott D.; Liba, Orly; de la Zerda, Adam

    2016-01-01

    We have developed a model to accurately quantify the signals produced by exogenous scattering agents used for contrast-enhanced Optical Coherence Tomography (OCT). This model predicts distinct concentration-dependent signal trends that arise from the underlying physics of OCT detection. Accordingly, we show that real scattering particles can be described as simplified ideal scatterers with modified scattering intensity and concentration. The relation between OCT signal and particle concentration is approximately linear at concentrations lower than 0.8 particle per imaging voxel. However, at higher concentrations, interference effects cause signal to increase with a square root dependence on the number of particles within a voxel. Finally, high particle concentrations cause enough light attenuation to saturate the detected signal. Predictions were validated by comparison with measured OCT signals from gold nanorods (GNRs) prepared in water at concentrations ranging over five orders of magnitude (50 fM to 5 nM). In addition, we validated that our model accurately predicts the signal responses of GNRs in highly heterogeneous scattering environments including whole blood and living animals. By enabling particle quantification, this work provides a valuable tool for current and future contrast-enhanced in vivo OCT studies. More generally, the model described herein may inform the interpretation of detected signals in modalities that rely on coherence-based detection or are susceptible to interference effects.

  6. Anatomic Optical Coherence Tomography of Upper Airways

    Chin Loy, Anthony; Jing, Joseph; Zhang, Jun; Wang, Yong; Elghobashi, Said; Chen, Zhongping; Wong, Brian J. F.

    The upper airway is a complex and intricate system responsible for respiration, phonation, and deglutition. Obstruction of the upper airways afflicts an estimated 12-18 million Americans. Pharyngeal size and shape are important factors in the pathogenesis of airway obstructions. In addition, nocturnal loss in pharyngeal muscular tone combined with high pharyngeal resistance can lead to collapse of the airway and periodic partial or complete upper airway obstruction. Anatomical optical coherence tomography (OCT) has the potential to provide high-speed three-dimensional tomographic images of the airway lumen without the use of ionizing radiation. In this chapter we describe the methods behind endoscopic OCT imaging and processing to generate full three dimensional anatomical models of the human airway which can be used in conjunction with numerical simulation methods to assess areas of airway obstruction. Combining this structural information with flow dynamic simulations, we can better estimate the site and causes of airway obstruction and better select and design surgery for patients with obstructive sleep apnea.

  7. Polarization sensitive optical coherence tomography detection method

    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

  8. Anterior Eye Imaging with Optical Coherence Tomography

    Huang, David; Li, Yan; Tang, Maolong

    The development of corneal and anterior segment optical coherence tomography (OCT) technology has advanced rapidly in recently years. The scan geometry and imaging wavelength are both important choices to make in designing anterior segment OCT systems. Rectangular scan geometry offers the least image distortion and is now used in most anterior OCT systems. The wavelength of OCT light source affects resolution and penetration. An optimal choice of the OCT imaging wavelength (840, 1,050, or 1,310 nm) depends on the application of interest. Newer generation Fourier-domain OCT technology can provide scan speed 100-1000 times faster than the time-domain technology. Various commercial anterior OCT systems are available on the market. A wide spectrum of diagnostic and surgical applications using anterior segment OCT had been investigated, including mapping of corneal and epithelial thicknesses, keratoconus screening, measuring corneal refractive power, corneal surgery planning and evaluation in LASIK, intracorneal ring implantation, assessment of angle closure glaucoma, anterior chamber biometry and intraocular lens implants, intraocular lens power calculation, and eye bank donor cornea screening.

  9. Space-division multiplexing optical coherence tomography.

    Zhou, Chao; Alex, Aneesh; Rasakanthan, Janarthanan; Ma, Yutao

    2013-08-12

    High speed, high resolution and high sensitivity are desirable for optical coherence tomography (OCT). Here, we demonstrate a space-division multiplexing (SDM) technology that translates long coherence length of a commercially available wavelength tunable laser into high OCT imaging speed. We achieved an effective 800,000 A-scans/s imaging speed using a 100,000 Hz tunable vertical cavity surface-emitting laser (VCSEL). A sensitivity of 94.6 dB and a roll-off of < 2 dB over ~30 mm imaging depth were measured from a single channel in the prototype SDM-OCT system. An axial resolution of ~11 μm in air (or ~8.3 μm in tissue) was achieved throughout the entire depth range. An in vivo, 3D SDM-OCT volume of an entire Drosophila larva consisting of 400 x 605 A-scans was acquired in 0.37 seconds. Synchronized cross-sectional OCT imaging of three different segments of a beating Drosophila larva heart is demonstrated. The SDM technology provides a new orthogonal dimension for further speed improvement for OCT with favorable cost scaling. SDM-OCT also preserves image resolution and allows synchronized cross-sectional and three-dimensional (3D) imaging of biological samples, enabling new biomedical applications. PMID:23938839

  10. Frequency Domain Optical Coherence Tomography Techniques in Eye Imaging

    Wojtkowski, M.; Kowalczyk, A.; Targowski, P.; Gorczyñska, I.

    2000-12-01

    This contribution presents an application of frequency-domain optical tomography to ophthalmology. Essential theoretical foundations of time-domain and frequency-domain optical tomography are presented. Images of sections through the anterior chamber, the corneo-scleral angle and fundus of the eye are reconstructed from the spectral fringes. The morphological information gained by tomograms is important for diagnosing and planning of a treatment of glaucoma.

  11. Digital optical tomography system for dynamic breast imaging

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

    2011-01-01

    Diffuse optical tomography has shown promising results as a tool for breast cancer screening and monitoring response to chemotherapy. Dynamic imaging of the transient response of the breast to an external stimulus, such as pressure or a respiratory maneuver, can provide additional information that can be used to detect tumors. We present a new digital continuous-wave optical tomography system designed to simultaneously image both breasts at fast frame rates and with a large number of sources ...

  12. Engineered microsphere contrast agents for optical coherence tomography

    Lee, Tin Man; Oldenburg, Amy L.; Sitafalwalla, Shoeb; Marks, Daniel L.; Luo, Wei; Toublan, Farah Jean-Jacques; Suslick, Kenneth S.; Boppart, Stephen A.

    2003-09-01

    Contrast agents are utilized in virtually every imaging modality to enhance diagnostic capabilities. We introduce a novel class of optical contrast agent, namely, encapsulating microspheres, that are based not on fluorescence but on scattering nanoparticles within the shell or core. The agents are suitable for reflection- or scattering-based techniques such as optical coherence tomography, light microscopy, and reflectance confocal microscopy. We characterize the optical properties of gold-, melanin-, and carbon-shelled contrast agents and demonstrate enhancement of optical coherence tomography imaging after intravenous injection of such an agent into a mouse.

  13. Optical characterization of vocal folds using optical coherence tomography

    Lüerßen, Kathrin; Lubatschowski, Holger; Radicke, Nicole; Ptok, Martin

    2006-02-01

    The current standard procedure to ensure the diagnosis, if tissue is malignant, is still an invasive one. Optical coherence tomography (OCT) is a new non-invasive method to investigate biological tissue. In this study OCT was used on porcine and on human vocal folds. The optical penetration depth of the used radiation is up to 2 mm. Three different OCT application systems were used. The first is a high resolution OCT, which works in contact mode. It was used to examine porcine vocal folds ex vivo. Porcine vocal folds were assigned to defined areas and examined by OCT in contact mode followed by traditional histo-morphological analysis. The second OCT is fiber based. It also works in contact mode. Images of human vocal folds were done in contact mode. They were compared with a typical histo-morphological image of a human vocal fold. The third application system works in non contact to the tissue. It was integrated in a conventional laryngoscope. Human vocal folds were examined in vivo. Single layers of the vocal folds could be distinguished from each other with all used systems. Pathological alterations could be seen. Imaging is possible in real time. General anaesthesia is not necessary. OCT makes it possible to get a view under the surface of the vocal fold without being invasive.

  14. Nano-sensitive optical coherence tomography

    Alexandrov, Sergey A.; Subhash, Hrebesh M.; Zam, Azhar; Leahy, Martin

    2014-03-01

    Depth resolved label-free detection of structural changes with nanoscale sensitivity is an outstanding problem in the biological and physical sciences and has significant applications in both the fundamental research and healthcare diagnostics arenas. Here we experimentally demonstrate a novel label-free depth resolved sensing technique based on optical coherence tomography (OCT) to detect structural changes at the nanoscale. Structural components of the 3D object, spectrally encoded in the remitted light, are transformed from the Fourier domain into each voxel of the 3D OCT image without compromising sensitivity. Spatial distribution of the nanoscale structural changes in the depth direction is visualized in just a single OCT scan. This label free approach provides new possibilities for depth resolved study of pathogenic and physiologically relevant molecules in the body with high sensitivity and specificity. It offers a powerful opportunity for early diagnosis and treatment of diseases. Experimental results show the ability of the approach to differentiate structural changes of 30 nm in nanosphere aggregates, located at different depths, from a single OCT scan, and structural changes less than 30 nm in time from two OCT scans. Application for visualization of the structure of human skin in vivo is also demonstrated.Depth resolved label-free detection of structural changes with nanoscale sensitivity is an outstanding problem in the biological and physical sciences and has significant applications in both the fundamental research and healthcare diagnostics arenas. Here we experimentally demonstrate a novel label-free depth resolved sensing technique based on optical coherence tomography (OCT) to detect structural changes at the nanoscale. Structural components of the 3D object, spectrally encoded in the remitted light, are transformed from the Fourier domain into each voxel of the 3D OCT image without compromising sensitivity. Spatial distribution of the nanoscale structural changes in the depth direction is visualized in just a single OCT scan. This label free approach provides new possibilities for depth resolved study of pathogenic and physiologically relevant molecules in the body with high sensitivity and specificity. It offers a powerful opportunity for early diagnosis and treatment of diseases. Experimental results show the ability of the approach to differentiate structural changes of 30 nm in nanosphere aggregates, located at different depths, from a single OCT scan, and structural changes less than 30 nm in time from two OCT scans. Application for visualization of the structure of human skin in vivo is also demonstrated. Electronic supplementary information (ESI) available: Theory of the nsOCT. Figure: axial spatial period profiles for two selected points within the sample for second and fiftieth frames and averaged over all frames before (0 nm) and after (30 nm) nanoscale structural changes. Videos 1 and 2: axial spatial period profiles for selected points within tubes with intralipid versus time where fast structural changes can be seen. Videos 3 and 4: axial spatial period profiles for selected points outside from tubes with intralipid versus time where slow structural changes can be seen. Video 5: nsOCT imaging of the structural changes within tubes with intralipid. Videos 6 and 8: axial spatial period profiles for selected points within human fingertip versus time where slow structural changes can be seen. Videos 7 and 9: axial spatial period profiles for selected points within human fingertip versus time where fast structural changes can be seen. Video 10: nsOCT imaging of the structural changes within human fingertip in vivo. See DOI: 10.1039/c3nr06132a

  15. Coherent noise remover for optical projection tomography

    Shi, Liangliang; Dong, Di; Yang, Yujie; Wang, Jun; Arranz, Alicia; Ripoll, Jorge; Tian, Jie

    2015-03-01

    Optical Projection Tomography (OPT) is a 3-Dimentional (3D) imaging technique for small specimens between 1mm and 10mm in size. Due to its high resolution and whole-body imaging ability, OPT has been widely used for imaging of small specimens such as murine embryos, murine organs, zebra fish, and plant sections. During an OPT imaging experiment, the ring artifacts are very common which severely impact the image quality of OPT. A ring artifact is caused by a bad pixel on the camera, or impurities on surface of lens and index matching vessel. Here we term these noises as coherent noise because they stay in the same image region during an OPT experiment. Currently, there is still no effective method to remove coherent noises. To address this problem, we propose a novel method to suppress the coherent noises before 3D OPT reconstruction. Our method consists of two steps: 1) find bad pixel positions on a blank image without specimen by using threshold segmentation, then fix the bad pixels on the projection image by using average of their neighbor pixels, 2) remove remained coherent noises on the sinogram by using Variational Coherent noise Remover (VSNR) method. After the two steps, lots of method can be used to generate the tomographic slices from the modified sinograms. We apply our method to a mouse heart imaging with our home-made OPT system. The experimental results show that our method has a good suppression on coherent noise and greatly improves the image quality. The innovation of our method is that we remove coherent noise automatically from both projection image and sinogram and they complement each other.

  16. Carious growth monitoring with optical coherence tomography

    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 μW in the sample arm, providing a 23 μm of axial resolution. The images were produced with lateral scans step of 10 μm. 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 μm to 230 μm, 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.

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

    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.

  18. Cryosurgery treatment of actinic keratoses monitored by optical coherence tomography

    Themstrup, L.; Banzhaf, C.; Jemec, G.B.E.; Mogensen, M.

    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...

  19. Quantum optical coherence tomography of a biological sample

    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.

  20. OPTICAL COHERENCE TOMOGRAPHY IN JUVENILE NEURONAL CEROID LIPOFUSCINOSIS

    Hansen, Michael S; Hove, Marianne Nørgaard; Jensen, Hanne; Larsen, Michael

    2016-01-01

    PURPOSE: To report optical coherence tomography findings obtained in two patients with juvenile neuronal ceroid lipofuscinosis. METHODS: Two case reports. RESULTS: Two 7-year-old girls presented with decreased visual acuity, clumsiness, night blindness, and behavioral problems. Optical coherence...... tomography showed an overall reduction in thickness of the central retina, as well as the outer and the inner retinal layers. The degenerative retinal changes were the same, despite different mutations in the CLN3 gene. CONCLUSION: In these rare cases of juvenile neuronal ceroid lipofuscinosis, optical...

  1. Functional swept source optical coherence tomography

    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)

  2. Towards multimodal nonlinear optical tomography – experimental methodology

    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

  3. Development of Fourier domain optical coherence tomography

    Wang, Rui

    Fourier domain optical coherence tomography (FD-OCT) is a high-speed, high-resolution, and noninvasive imaging technique that can obtain cross-sectional images of light scattering medium, such as biomedical tissues. In this thesis, I report three novel methods in FD-OCT technique including common-path endoscopic FD-OCT, streak-mode FD-OCT, and Doppler streak-mode FD-OCT. Finally, I apply the streak mode FD-OCT to ultrahigh-speed, noninvasive, live imaging of embryonic chick hearts. An extension of conventional FD-OCT technique is endoscopic FD-OCT, which can access internal organs by utilizing a miniaturized catheter design. However, its image signal suffers from the bending of the endoscopic catheter. To address this problem, a common-path endoscopic FD-OCT system was developed to avoid the polarization mismatch. Consequently, the OCT images were immune to the catheter bending. In addition, a Microelectromechanical system (MEMS) motor was integrated into the miniaturized probe to achieve circumferential scanning within lumen samples. In conventional FD-OCT, the imaging speed is limited by the slow line-scan rate of the camera. We developed the streak-mode FD-OCT technique, in which an area-scan camera is used instead of a line-scan camera to record the FD-OCT spectrum. Using this technique, high temporal resolution of 1000--2000 cross-sectional images of the sample were obtained in one second. Doppler FD-OCT is a functional extension of FD-OCT technique, which can measure the flow velocity within biomedical tissues. However, conventional techniques are not available to measure high speed flow due to slow imaging speed, phase wrapping, and fringe wash out issues. Based on the streak mode FD-OCT, a novel Doppler technique was developed that addressed these problems. It has been well established that cardiac dynamics play an important role in the early development of an embryonic heart. However, the mechanism by which cardiac dynamics affect the development of a peristaltic tube into a four-chambered heart is still unclear. This is mainly due to lack of investigative tools, such as an imaging technique with sufficiently high spatial and temporal resolution. Using streak-mode FD-OCT, 4D (3D + time) images of beating hearts have been reconstructed. This marks the first time that the embryonic animal heart has been 4D imaged using a megahertz OCT.

  4. ROLE OF OPTICAL COHERENCE TOMOGRAPHY IN CENTRAL SEROUS CHORIORETINOPATHY

    Junaid Salam

    2015-06-01

    Full Text Available PURPOSE: To study the role of optical coherence tomography in central serous chorioretinopathy. MATERIAL AND METHODS: A total of 48 eyes of 48 patients with a clinical diagnosis of central serous chorioretinopathy were eval uated with spectral domain optical coherence tomography. After detailed ocular examination, followed by fundus fluorescein angiography, optical coherence tomography was performed and various anatomic features were noted. RESULTS: Out of 48 eyes, 41 had acu te and 7 had chronic central serous chorioretinopathy. The mean age of the patients was 35 (SD 7 . 1 years with male (83 . 4% preponderance in our study. All patients had unilateral involvement with blurring of vision (43 . 75% and metamorphopsia (31 . 25% bein g the main presenting complaints. Fundus fluorescein angiography revealed a total of 56 leakage points with ink - blot pattern being 6 times more frequent than smoke - stack pattern in our study. On optical coherence tomography neurosensory detachment was see n in 44 eyes. Total macular thickness ranged from 220μm - 1120μm (mean±SD : 447±219 and vault height ranged from 100μm - 900μm (mean±SD : 350±187. Retinal pigment epithelial abnormality was seen in 87 . 5 % eyes, retinal pigment epithelial detachment in 18.75 % e yes and retinal pigment epithelial bulge in 27 . 09% patients. CONCLUSION: Optical coherence tomography can be used as a complimentary diagnostic tool in central serous chorioretinopathy.

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

    Precht, Helle; Leth, Peter Mygind; Thygesen, Jesper; Hardt-Madsen, Michael; Nielsen, Bjarne; Falk, Erling; Egstrup, Kenneth; Gerke, Oke; Broersen, Alexander; Kitslaar, Pieter H.; Dijkstra, Jouke; Lambrechtsen, Jess

    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...

  6. Imaging of the Rotator Cuff With Optical Coherence Tomography.

    Hartshorn, Timothy; Ren, Jian; Vangsness, C Thomas

    2015-09-01

    This study evaluated the utility of optical coherence tomography (OCT) in imaging porcine and human rotator cuff (RTC) tissue, analyzed its effectiveness in identifying clinical pathology, and correlated these findings with histologic examination. Twelve human cadaveric and 6 porcine shoulders were evaluated. Six-millimeter-wide bone sections were harvested from the proximal humerus of each specimen, with each containing the entire enthesis of the respective RTC tendon, as well as 2 cm of tendon medial to the enthesis. Only the supraspinatus tendon was evaluated in the human specimens, whereas the enthesis of multiple RTC tendons were evaluated in the porcine model. All specimens were imaged using OCT and correlated with histologic evaluation. Optical coherence tomography evaluation of macroscopically healthy tissue consistently showed an easily identifiable banding pattern (birefringence) in contrast to a disorganized, homogeneous appearance in grossly diseased tissue. Optical coherence tomography was more effective for qualitative evaluation of RTC tissue, identification of bursal-sided RTC tears, and localization of calcific deposits, whereas intrasubstance tendon delaminations and partial articular-sided tendon avulsion lesions were relatively more difficult to identify. Optical coherence tomography correlated well with histologic evaluation in all specimens. Optical coherence tomography provides high-resolution, subsurface imaging of rotator cuff tissue in real-time to a depth of up to 4 mm with excellent correlation to histology in a cadaveric model. Optical coherence tomography could be an effective adjunctive tool for the identification and localization of rotator cuff pathology. The use of OCT in arthroscopic shoulder surgery potentially provides a minimally invasive modality for qualitative assessment of rotator cuff pathology. This may allow for a decrease in soft tissue dissection, improved qualitative assessment of cuff tissue, and improved patient outcomes. PMID:26375544

  7. Optical atomic magnetometry for magnetic induction tomography of the heart

    Deans, Cameron; Hussain, Sarah; Renzoni, Ferruccio

    2016-01-01

    We report on the use of radio-frequency optical atomic magnetometers for magnetic induction tomography measurements. We demonstrate the imaging of dummy targets of varying conductivities placed in the proximity of the sensor, in an unshielded environment at room-temperature and without background subtraction. The images produced by the system accurately reproduce the characteristics of the actual objects. Furthermore, we perform finite element simulations in order to assess the potential for measuring low-conductivity biological tissues with our system. Our results demonstrate the feasibility of an instrument based on optical atomic magnetometers for magnetic induction tomography imaging of biological samples, in particular for mapping anomalous conductivity in the heart.

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

    Larsen, Henning Engelbrecht; Nilsson, Ronnie Thorup; Thrane, Lars; Pedersen, Finn; Jørgensen, Thomas Martini; Andersen, Peter E.

    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....

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

    Michael F Joseph

    2010-03-01

    Full Text Available Michael F Joseph1, Craig R Denegar1, Elaine Horn1, Bradley MacDougall1, Michael Rahl1, Jessica Sheehan1, Thomas Trojian2, Jeffery M Anderson1, James E Clark1, William J Kraemer11Department of Kinesiology, 2Department of Sports Medicine, University of Connecticut, Storrs, CT, USAAbstract: Lower extremity mechanics during landing have been linked to traumatic and nontraumatic knee injuries, particularly in womens athletics. The effects of efforts to mitigate these risks have not been fully elucidated. We previously reported that a 5 medial wedge reduced ankle eversion and knee valgus. In the present report we further investigated the effect of a 5 medial wedge inserted in the shoes of female athletes on frontal plane hip motion, as well as ankle, knee, hip, and trunk saggital plane motion during a jump landing task. Kinematic data were obtained from 10 intercollegiate female athletes during jump landings from a 31 cm platform with and without a 5 medial wedge. Hip adduction was reduced 1.98 (95% CI 0.972.99 by the medial wedge but saggital plane motions were unaffected. A 5 medial wedge reduces frontal plane motion and takes the knee away from a position associated with anterior cruciate ligament injury and patellofemoral pain syndrome. Although frontal plane motion was not captured it is unlikely to have increased in a bilateral landing task. Thus, it is likely that greater muscle forces were generated in these highly trained athletes to dissipate ground reaction forces when a medial wedge was in place. Additional investigation in younger and lesser trained athletes is warranted to assess the impact of orthotic devices on knee joint mechanics.Keywords: jump landing, foot orthotic, lower extremity kinematics, knee biomechanics, knee injury

  10. Topological sensitivity analysis in fluorescence optical tomography

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

  11. Optical Magnetic Induction Tomography of the Heart

    Marmugi, L.; Renzoni, F.

    2016-01-01

    Atrial Fibrillation (AF) affects a significant fraction of the ageing population, causing a high level of morbidity and mortality. Despite its significance, the causes of AF are still not uniquely identified. This, combined with the lack of precise diagnostic and guiding tools, makes the clinical treatment of AF sub-optimal. We identify magnetic induction tomography as the most promising technique for the investigation of the causes of fibrillation and for its clinical practice. We therefore ...

  12. Design and fabrication of optical polymer waveguide devices for optical interconnects and integrated optical coherence tomography

    Jiang, Guomin

    Optical interconnects is a promising technique to boost the speed of electronic systems through replacing high speed electrical data buses using optical ones. Optical coherence tomography is an attractive imaging technique that has been widely used in medical imaging applications with capability of high resolution subsurface cross sectional imaging in living tissues. Both the optical interconnects and the optical coherence tomography imaging may benefit from the use of integrated optics technology in particular polymer waveguides that can be designed and fabricated to improve the device capability, system compactness, and performance reliability. In this dissertation, we first present our innovative design and realization on the polymer waveguides with 45° integrated mirrors for optical interconnects using the vacuum assisted microfluidic (VAM) soft lithography. VAM is a new microfluidic based replication technique which can be utilized to improve the performance of imprinted devices by eliminating the residue planar layer and accomplish complex devices incorporating different materials in the same layer. A prism-assisted inclined UV lithography technique is introduced to increase the slanted angles of the side walls of the microstructures and to fabricate multidirectional slanted microstructures. It is also used to fabricate 45° integrated mirrors in polymer waveguides to support surface normal optical coupling for optical interconnects. A dynamic card-to-backplane optical interconnects system has also been demonstrated based on polymer waveguides with tunable optofluidic couplers. The operation of the tunable optofluidic coupler is accomplished by controlling the position of air bubbles and index matching liquid in the perpendicular microfluidic channel for refractive index modulation. The dynamic activation and deactivation of the backplane optofluidic couplers can save the optical signal power. 10 Gbps eye diagrams of the dynamic optical interconnect link have been demonstrated showing the needed high performance optical interconnection. The design and fabrication of planar concave grating (PCG) wavelength demultiplexer on SU-8 polymer waveguides is presented for wavelength division multiplexing system to further support optical interconnection applications. The PCG wavelength demultiplexers with a flattened spectral response are accomplished by innovative design of a multi-mode interference coupler as input to the PCG. The mode field distribution at the PCG planar input is controlled by adjusting the width of an input waveguide taper connected to multi-mode interference coupler. By extending the channel number and density, the PCG wavelength demultiplexer can become a compact optical spectrometer which could be used to realize a portable optical coherence tomography system. The design of a 200-channel and a 1024-channel PCG spectrometers with low crosstalk, small channel loss, good uniformity, and chip size of 3 cm x 3 cm and 8 cm x 8 cm, respectively, has been performed. An alternative quicker solution using cylindrical optics with a vertical beam size of about 3 mm in the diffraction plane is also demonstrated to achieve a compact optical spectrometer, which is capable of supporting optical coherence tomography subsurface imaging applications.

  13. ASSESSMENT OF TISSUE OPTICAL CLEARING AS A FUNCTION OF GLUCOSE CONCENTRATION USING OPTICAL COHERENCE TOMOGRAPHY

    Sudheendran, Narendran; Mohamed, Mohamed; Ghosn, Mohamad G; Tuchin, Valery V.; Larin, Kirill V

    2010-01-01

    One of the major challenges in imaging biological tissues using optical techniques, such as optical coherence tomography (OCT), is the lack of light penetration due to highly turbid structures within the tissue. Optical clearing techniques enable the biological samples to be more optically homogeneous, allowing for deeper penetration of light into the tissue. This study investigates the effect of optical clearing utilizing various concentrations of glucose solution (10%, 30%, and 50%) on porc...

  14. Noninvasive evaluation of retinal leakage using optical coherence tomography

    Bernardes, Rui; Santos, Torcato; Serranho, Pedro; Lobo, Conceição; Cunha-Vaz, José

    2011-01-01

    Purpose: To demonstrate the association between changes in the blood-retinal barrier (BRB) identified by fluorescein leakage and those in the optical properties of the human retina determined by optical coherence tomography (OCT) and show how these changes can be quantified and their location identified within the retina. Methods: Two imaging techniques were applied: the retinal leakage analyzer, to map BRB function into intact or disrupted regions, and OCT, to measure refractive index change...

  15. Spectral domain optical coherence tomography and microperimetry in foveal hypoplasia

    Swakshyar Saumya Pal

    2011-01-01

    Full Text Available A case of foveal hypoplasia associated with ocular albinism with anatomic and functional changes by various techniques using spectral domain optical coherence tomography (SD-OCT, microperimeter and confocal scanning laser ophthalmoscope is described. This case highlights the importance of microperimeter in detecting the functional abnormalities of vision and SD-OCT in identifying the retinal laminar abnormalities in foveal hypoplasia.

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

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

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

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

    2005-01-01

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

  18. Spectral domain optical coherence tomography and microperimetry in foveal hypoplasia

    Pal, Swakshyar Saumya; Gella, Laxmi; Sharma, Tarun; Raman, Rajiv

    2011-01-01

    A case of foveal hypoplasia associated with ocular albinism with anatomic and functional changes by various techniques using spectral domain optical coherence tomography (SD-OCT), microperimeter and confocal scanning laser ophthalmoscope is described. This case highlights the importance of microperimeter in detecting the functional abnormalities of vision and SD-OCT in identifying the retinal laminar abnormalities in foveal hypoplasia. PMID:22011499

  19. Optical coherence tomography changes in macular CMV retinitis

    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

    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 significance of computed tomography in optic neuropathy

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

  2. Polarization-Sensitive Quantum Optical Coherence Tomography: Experiment

    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. Automated optic-nerve-head analysis using optical coherence tomography

    Kulkarni, Manish D.; Harman, Jonathan W.; Kim, Robert; Kirschbaum, Alan R.; Pedersen, Per; Everett, Matthew J.; Wei, Jay

    2002-06-01

    The early identification of glaucomatous development is extremely important for treatment of glaucoma. Analysis of optic-nerve-head features may play a crucial role for early glaucoma diagnostics. Here we propose a critical parameter, viz., nerve tissue area, which may prove to be extremely useful for detection of glaucoma in early stages. We report a novel and robust algorithm for OCT-based automatic, objective extraction of critical optic-nerve-head features such as optic disc, nerve tissue area, and optic cup for the first time.

  4. Quantum-optical coherence tomography with dispersion cancellation

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

  5. Diffuse optical tomography based on multiple access coding

    Wang, Xuefeng; Wang, Yuanqing; Su, Jinshan; Xu, Fan

    2016-04-01

    Diffuse optical tomography (DOT) has the advantages of being a non-invasive, non-radiation emitting and low-cost biological tissue imaging method, and many recent studies have employed this technology. By improving the spatial resolution and developing a new method for constantly improving the flexibility of the experimental device, the system can perform data acquisition rapidly and conveniently. We propose a method for rapid data acquisition based on multiple access coding; it can acquire data in parallel, and the system can greatly improve the temporal resolution of the data acquisition step in diffuse optical tomography thereafter. We simulate the encoding and decoding process of the source-detector pair and successfully isolate the source signal from mixed signals. The DOT image reconstruction highlight the effectiveness of the system.

  6. Digital optical tomography system for dynamic breast imaging

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

    2011-07-01

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

  7. Optical coherence tomography: A new strategy to image planarian regeneration

    Lin, Yu-Sheng; Chu, Chin-Chou; Lin, Jen-Jen; Chang, Chien-Cheng; Wang, Chun-Chieh; Wang, Chiao-Yin; Tsui, Po-Hsiang

    2014-01-01

    The planarian is widely used as a model for studying tissue regeneration. In this study, we used optical coherence tomography (OCT) for the real-time, high-resolution imaging of planarian tissue regeneration. Five planaria were sliced transversely to produce 5 head and 5 tail fragments. During a 2-week regeneration period, OCT images of the planaria were acquired to analyze the signal attenuation rates, intensity ratios, and image texture features (including contrast, correlation, homogeneity...

  8. Research progress on anterior segment optical coherence tomography in glaucoma

    Li Zhao; Qing-Song Li; Mei-Qing Ke; Xing-Ru Zhang

    2014-01-01

    Glaucoma is the second blindness disease in the world, and there are more primary angle closed glaucoma in China. The anatomy changes of the anterior chamber have close relationships with the development of glaucoma. Anterior segment optical coherence tomography(AS-OCT)has the advantages of fast, non-contact, high resolution and accurate quantitative measurement, which provides a kind of important method for finding the pathogenesis of primary angle closed glaucoma, for early diagnosis and tr...

  9. Multiple scattering in wide-field optical coherence tomography

    Karamata, Boris; Lasser, Theo

    2005-01-01

    Optical Coherence Tomography (OCT), a well-established imaging method based on low-coherence interferometry, provides cross-sectional images of the internal structure of biological samples with a resolution in the micrometer range. OCT was successfully applied on various tissues such as for instance the retina, the skin or a tooth. In highly scattering tissues like the skin, probing depth is limited to approximately 2mm, mainly due to insufficient rejection of multiply scattered light. Presen...

  10. In vivo feasibility of endovascular Doppler optical coherence tomography

    Sun, Cuiru; Nolte, Felix; Cheng, Kyle H. Y.; Vuong, Barry; Lee, Kenneth K. C.; Standish, Beau A.; Courtney, Brian; Marotta, Thomas R.; Mariampillai, Adrian; Yang, Victor X. D.

    2012-01-01

    Feasibility of detecting intravascular flow using a catheter based endovascular optical coherence tomography (OCT) system is demonstrated in a porcine carotid model in vivo. The effects of A-line density, radial distance, signal-to-noise ratio, non-uniform rotational distortion (NURD), phase stability of the swept wavelength laser and interferometer system on Doppler shift detection limit were investigated in stationary and flow phantoms. Techniques for NURD induced phase shift artifact remov...

  11. Anatomical atlas-guided diffuse optical tomography of brain activation

    Custo, Anna; Boas, David A; Tsuzuki, Daisuke; Dan, Ippeita; Mesquita, Rickson; Fischl, Bruce; Grimson, W. Eric L.; Wells, Williams

    2009-01-01

    We describe a neuro imaging protocol that utilizes an anatomical atlas of the human head to guide Diffuse optical tomography of human brain activation. The protocol is demonstrated by imaging the hemodynamic response to median nerve stimulation in three healthy subjects, and comparing the images obtained using a head atlas with the images obtained using the subject-specific head anatomy. The results indicate that using the head atlas anatomy it is possible to reconstruct the location of the b...

  12. Tomography and optical properties of silver nano-inukshuk

    Ghosh, Tanmay; Das, Pabitra; Ghosh, Tapas; Satpati, Biswarup

    2015-06-01

    Following a simple dip-and-rinse galvanic displacement reaction silver nano-inukshuks were prepared directly on germanium surfaces. Morphology, 3-dimensional (3D) structure, chemical composition and optical properties of the silver nanostructurs were investigated using scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectroscopy (EDX), and cathodoluminescence (CL) spectroscopy. Exact 3D morphology was reconstructed in the by tomography mode of TEM.

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

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

    2010-01-01

    Three dimensional (3D) ophthalmic imaging using optical coherence tomography (OCT) has revolutionized assessment of the eye, the retina in particular. Recent technological improvements have made the acquisition of 3D-OCT datasets feasible. However, while volumetric data can improve disease diagnosis and follow-up, novel image analysis techniques are now necessary in order to process the dense 3D-OCT dataset. Fundamental software improvements include methods for correcting subject eye motion, ...

  14. Ultrasound induced improvement in optical coherence tomography (OCT) resolution

    Schenk, John O.; Brezinski, Mark E.

    2002-01-01

    Optical coherence tomography (OCT) is a rapidly emerging technology for high-resolution biomedical imaging. The axial resolution of this technology is determined by the bandwidth of the source. Commercial sources generally provide resolutions of 10–20 μm whereas laboratory-based solid state lasers have resolutions of ≈4 μm. The resolution in tissue depends almost exclusively on detecting single scattered events. However, the phenomenon known as multiple scattering results in a deterioration o...

  15. Heartbeat OCT: in vivo intravascular megahertz-optical coherence tomography

    Wang, Tianshi; Pfeiffer, Tom; Regar, Evelyn; Wieser, Wolfgang; Van Beusekom, Heleen; Lancee, Charles T.; Springeling, Geert; Krabbendam, Ilona; Van Der Steen, Antonius F.W.; Huber, Robert; Soest, Gijs

    2015-01-01

    Cardiac motion artifacts, non-uniform rotational distortion and undersampling affect the image quality and the diagnostic impact of intravascular optical coherence tomography (IV-OCT). In this study we demonstrate how these limitations of IV-OCT can be addressed by using an imaging system that we called “Heartbeat OCT”, combining a fast Fourier Domain Mode Locked laser, fast pullback, and a micromotor actuated catheter, designed to examine a coronary vessel in less than one cardiac cycle. We ...

  16. Optical Coherence Tomography of Retinal and Choroidal Tumors

    Shields, Carol L.; Sandor Ferenczy; Sanket U. Shah; Emil Anthony T. Say

    2011-01-01

    Optical coherence tomography (OCT) has revolutionized the field of ophthalmology since its introduction 20 years ago. Originally intended primarily for retina specialists to image the macula, it has found its role in other subspecialties that include glaucoma, cornea, and ocular oncology. In ocular oncology, OCT provides axial resolution to approximately 7 microns with cross-sectional images of the retina, delivering valuable information on the effects of intraocular tumors on the retinal arc...

  17. Submicron Resolution Spectral-Domain Optical Coherence Tomography

    Alarousu, Erkki

    2013-11-14

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

  18. Multiple and dependent scattering effects in Doppler optical coherence tomography

    Kalkman, J.; A V Bykov; Faber, D.J.; Leeuwen, van, M.

    2010-01-01

    Doppler optical coherence tomography (OCT) is a technique to image tissue morphology and to measure flow in turbid media. In its most basic form, it is based on single (Mie) scattering. However, for highly scattering and dense media multiple and concentration dependent scattering can occur. For Intralipid solutions with varying scattering strength, the effect of multiple and dependent scattering on the OCT signal attenuation and Doppler flow is investigated. We observe a non-linear increase i...

  19. Analysis of skin lesions using laminar optical tomography

    Muldoon, Timothy J.; Burgess, Sean A.; Chen, Brenda R; Ratner, Dsire; Hillman, Elizabeth M. C.

    2012-01-01

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

  20. Multifocal Cysticercosis with Optical Coherence Tomography Findings in a Child

    Mrs Manisha Agarwal; Vivek Jha; Chaudhary, Somendra P.; Singh, Ashok K.

    2012-01-01

    We herein report a case with multifocal cysticercosis - sub-conjunctival cysticercus cyst, sub-retinal cysticercosis, and neurocysticercosis in a child. The optical coherence tomography (OCT) findings of the sub-retinal cysticercus cyst are reported. He was treated with anti-helminthic drugs and oral prednisolone followed by surgical removal of the sub-retinal cyst. He subsequently underwent silicone oil removal with lens aspiration and intraocular lens implantation maintaining stable vision

  1. Multifocal cysticercosis with optical coherence tomography findings in a child

    Manisha Agarwal

    2012-01-01

    Full Text Available We herein report a case with multifocal cysticercosis - sub-conjunctival cysticercus cyst, sub-retinal cysticercosis, and neurocysticercosis in a child. The optical coherence tomography (OCT findings of the sub-retinal cysticercus cyst are reported. He was treated with anti-helminthic drugs and oral prednisolone followed by surgical removal of the sub-retinal cyst. He subsequently underwent silicone oil removal with lens aspiration and intraocular lens implantation maintaining stable vision

  2. Autocorrelation optical coherence tomography for glucose quantification in blood

    Ullah, H.; Gilanie, G.; Hussain, F.; Ahmad, E.

    2015-12-01

    We report a new method for glucose monitoring in blood tissue based on the autocorrelation function (ACF) analysis in Fourier domain optical coherence tomography (FD-OCT). We have determined the changes in OCT monitoring signals depth to characterize the modulations in ACFs for quantitative measurements of glucose concentrations in blood. We found that an increase in the concentration of glucose in blood results in decreased OCT monitoring signal due to the increase in the refractive index of the media.

  3. An Optical Tomography System Using a Digital Signal Processor

    Mohd. Hafiz Fazalul Rahiman

    2008-03-01

    Full Text Available The use of a personal computer together with a Data Acquisition System (DAQ as the processing tool in optical tomography systems has been the norm ever since the beginning of process tomography. However, advancements in silicon fabrication technology allow nowadays the fabrication of powerful Digital Signal Processors (DSP at a reasonable cost. This allows this technology to be used in an optical tomography system since data acquisition and processing can be performed within the DSP. Thus, the dependency on a personal computer and a DAQ to sample and process the external signals can be reduced or even eliminated. The DSP system was customized to control the data acquisition process of 16x16 optical sensor array, arranged in parallel beam projection. The data collected was used to reconstruct the cross sectional image of the pipeline conveyor. For image display purposes, the reconstructed image was sent to a personal computer via serial communication. This allows the use of a laptop to display the tomogram image besides performing any other offline analysis.

  4. An Optical Tomography System Using a Digital Signal Processor

    Rahim, Ruzairi Abdul; Thiam, Chiam Kok; Fazalul Rahiman, Mohd Hafiz

    2008-01-01

    The use of a personal computer together with a Data Acquisition System (DAQ) as the processing tool in optical tomography systems has been the norm ever since the beginning of process tomography. However, advancements in silicon fabrication technology allow nowadays the fabrication of powerful Digital Signal Processors (DSP) at a reasonable cost. This allows this technology to be used in an optical tomography system since data acquisition and processing can be performed within the DSP. Thus, the dependency on a personal computer and a DAQ to sample and process the external signals can be reduced or even eliminated. The DSP system was customized to control the data acquisition process of 16×16 optical sensor array, arranged in parallel beam projection. The data collected was used to reconstruct the cross sectional image of the pipeline conveyor. For image display purposes, the reconstructed image was sent to a personal computer via serial communication. This allows the use of a laptop to display the tomogram image besides performing any other offline analysis.

  5. Optical coherence tomography for process control of laser micromachining.

    Wiesner, Markus; Ihlemann, Jürgen; Müller, Heike H; Lankenau, Eva; Hüttmann, Gereon

    2010-03-01

    In situ surface imaging for nondestructive evaluation (NDE) by optical coherence tomography (OCT) before, during, and after ablative laser processing is presented. Furthermore, it is shown that the ability of in situ characterization is beneficial for samples such as optical fibers, which are difficult to handle in the standard analysis. Surface images taken by the OCT are compared with these common analysis tools such as scanning electron microscopy (SEM), reflected-light, and confocal microscopy. An axial resolution of approximately 126 nm for surface detection and a lateral resolution <2.5 microm are obtained and the potential of the setup to imaging structures with high aspect ratio is demonstrated. PMID:20370183

  6. Optical Coherence Tomography: Modeling and Applications

    Thrane, Lars

    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...... 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...

  7. Fourier domain optical coherence tomography using optical frequency comb

    Bajraszewski, T.; Wojtkowski, M.; Szkulmowska, A.; Fojt, W.; Szkulmowski, M.; Kowalczyk, A.

    2007-02-01

    Novel Fourier domain OCT method and instrumentation using Optical Frequency Comb (OFC) is demonstrated. This technique can overcome some limitations of Spectral OCT and Optical Frequency domain Imaging (Swept Source OCT) and enables ultrahigh resolution imaging in 800 nm range. In the novel method external OFC generator placed after the broad band light source is used. We will demonstrate preliminary data showing the general performance, advantages and limitations of the Fourier domain OCT method using Optical Frequency Comb generator based on Fabry-Perot interferometer (F-P). High quality, high resolution cross-sectional images of biological samples obtained with the presented technique are shown.

  8. Frequency domain optical tomography using a Monte Carlo perturbation method

    Yamamoto, Toshihiro; Sakamoto, Hiroki

    2016-04-01

    A frequency domain Monte Carlo method is applied to near-infrared optical tomography, where an intensity-modulated light source with a given modulation frequency is used to reconstruct optical properties. The frequency domain reconstruction technique allows for better separation between the scattering and absorption properties of inclusions, even for ill-posed inverse problems, due to cross-talk between the scattering and absorption reconstructions. The frequency domain Monte Carlo calculation for light transport in an absorbing and scattering medium has thus far been analyzed mostly for the reconstruction of optical properties in simple layered tissues. This study applies a Monte Carlo calculation algorithm, which can handle complex-valued particle weights for solving a frequency domain transport equation, to optical tomography in two-dimensional heterogeneous tissues. The Jacobian matrix that is needed to reconstruct the optical properties is obtained by a first-order "differential operator" technique, which involves less variance than the conventional "correlated sampling" technique. The numerical examples in this paper indicate that the newly proposed Monte Carlo method provides reconstructed results for the scattering and absorption coefficients that compare favorably with the results obtained from conventional deterministic or Monte Carlo methods.

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

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

    2014-01-01

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

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

    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. (paper)

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

    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.

  12. A comprehensive method for optical-emission computed tomography

    Thomas, Andrew; Bowsher, James; Roper, Justin; Oliver, Tim; Dewhirst, Mark; Oldham, Mark

    2010-07-01

    Optical-computed tomography (CT) and optical-emission computed tomography (ECT) are recent techniques with potential for high-resolution multi-faceted 3D imaging of the structure and function in unsectioned tissue samples up to 1-4 cc. Quantitative imaging of 3D fluorophore distribution (e.g. GFP) using optical-ECT is challenging due to attenuation present within the sample. Uncorrected reconstructed images appear hotter near the edges than at the center. A similar effect is seen in SPECT/PET imaging, although an important difference is attenuation occurs for both emission and excitation photons. This work presents a way to implement not only the emission attenuation correction utilized in SPECT, but also excitation attenuation correction and source strength modeling which are unique to optical-ECT. The performance of the correction methods was investigated by the use of a cylindrical gelatin phantom whose central region was filled with a known distribution of attenuation and fluorophores. Uncorrected and corrected reconstructions were compared to a sectioned slice of the phantom imaged using a fluorescent dissecting microscope. Significant attenuation artifacts were observed in uncorrected images and appeared up to 80% less intense in the central regions due to attenuation and an assumed uniform light source. The corrected reconstruction showed agreement throughout the verification image with only slight variations (~5%). Final experiments demonstrate the correction in tissue as applied to a tumor with constitutive RFP.

  13. Large area full-field optical coherence tomography

    Chang, Shoude; Sherif, Sherif; Flueraru, Costel

    2006-09-01

    Optical Coherence Tomography (OCT) is a fundamentally new type of optical imaging technology. OCT performs high resolution, cross-sectional tomographic imaging of the internal structure in materials and biological systems. The biomedical applications of the OCT imaging systems have been developed for diagnostics of ophthalmology, dermatology, dentistry and cardiology. Most of existing OCT systems use point-scanning based technology, however, the 3-axis scanning makes the system slow and cumbersome. A few OCT systems working directly on 2D full-field images were reported, however, they are designed to work in a relatively small area, around couple of hundred microns square. In this paper, we present a design and implementation of a full-field OCT imaging system for acquiring tomography and with a working area around 15mm by 15 mm. The problems rising from full-field OCT are addressed and analyzed. The algorithms to extract the tomography are proposed. Two applications of multilayer information retrieval and 3D object imaging using full-field OCT are described.

  14. Piezoelectric scanning mirrors for endoscopic optical coherence tomography

    A novel piezoelectric scanning mirror design for endoscopic optical coherence tomography (OCT) is presented. OCT is an interferometric technique providing microscopic tomographic sectioning of biological samples with mm-range penetration capability in tissue and is suited for integration with endoscopes using fiber-based light delivery to the sample. The piezoelectric scanning mirror was designed to provide wide-range rapid forwarding-looking scanning of the optical beam at the distal end of a compact catheter. The optical scanner provides a large ratio of mirror aperture to device size with rectangular mirror sizes ranging from 600 m 840 m to 840 m 1600 m. Static angular displacements up to 7 (mechanical angle) were demonstrated and resonance frequencies of hundreds of Hz (and up to 12 kHz) were measured, depending on the mirror size. The imaging capability of the piezoelectric scanner was demonstrated using a bench-top spectrometer-based Fourier-domain OCT system

  15. Multispectral guided fluorescence diffuse optical tomography using upconverting nanoparticles

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

    2014-02-17

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

  16. The Giant Magellan Telescope Laser Tomography Adaptive Optics System

    Conan, Rodolphe; Bennet, Francis; Bouchez, Antonin; Van Dam, Marcos; Espeland, Brady; Gardouse, Warren; D'Orgeville, Celine; Paulin, N.; Piatrou, Piotr; Price, I.; Rigaut, François; Trancho, Gelys; Uhlendorf, Kristina

    2013-12-01

    Laser tomography adaptive optics (LTAO) will allow Extremely Large Telescope to get nearly diffraction limited images over a large fraction of the sky.For such systems, the sky coverage is limited by the number of natural guide star (NGS) suitable to estimate the tip and tilt (TT) modes of the atmosphere.The LTAO system of the Giant Magellan Telescope is using a single NGS which detector is located within the instrument. A deformable mirror (DM) in open--loop corrects the anisoplanatism error of the NGS wavefront.The DM command is derived from an off-axis tomographic reconstruction using the measurements from the Laser Guide Star wavefront sensors.The paper describes the tomography algorithm, a minimum variance reconstructor in the wavefront sensor space.The detail of the control architecture is shown including the TT, the focus and the truth sensors.As a conclusion, we will report on the expected sky coverage and performance of the system.

  17. A Low-Cost Method for Optical Tomography

    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

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

    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 μm depth and 31% enhancement in image depth Zthreshold.

  19. Custom software for third generation optical computed tomography

    The advanced radiotherapy techniques based on increased complexity of radiation delivery methods necessitate verification of computer calculated dose distribution by an accurate dosimetric method. The only emergent candidate with true three dimensional nature is the gel dosimeter. In spite of the three dimensional nature of the Optical Computed Tomography (OCT), most work so far has only used two-dimensional evaluations of the three dimensional data set. Recently this limitation has been overcome by applying the cone beam CT imaging principle to optical imaging. A CCD camera based OCT scanner was setup for gel dosimetry using the geometry suggested by J Wolodzko et al. and J Kevin. In an earlier work by the co-author the iradon function in Matlab was used for reconstruction of mid-slices assuming the cone angle to be negligible. In this study software was developed based on the algorithm by Feldkamp, Davis and Kress FDK to reconstruct the images for Optical Computed Tomography Scanner. Results are compared with the previous work of the co-author

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

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

    2012-11-01

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

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

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

    2012-01-01

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

  2. Extending the effective imaging range of Fourier domain optical coherence tomography using a fiber optic switch

    WANG, HUI; Pan, Yinsheng; Rollins, Andrew M.

    2008-01-01

    The effective imaging range of Fourier-domain optical coherence tomography is limited by fall-off. We present a very simple method to extend the effective imaging range with dual reference arms and a high speed fiber optic switch. The effective imaging range was increased by 1.8 with two reference arms compared with a single reference arm. Ex vivo tissue images showed significantly improved sensitivity over a large imaging range. Further extension of the imaging range is feasible with multipl...

  3. 3D parameter reconstruction in hyperspectral diffuse optical tomography

    Saibaba, Arvind K.; Krishnamurthy, Nishanth; Anderson, Pamela G.; Kainerstorfer, Jana M.; Sassaroli, Angelo; Miller, Eric L.; Fantini, Sergio; Kilmer, Misha E.

    2015-03-01

    The imaging of shape perturbation and chromophore concentration using Diffuse Optical Tomography (DOT) data can be mathematically described as an ill-posed and non-linear inverse problem. The reconstruction algorithm for hyperspectral data using a linearized Born model is prohibitively expensive, both in terms of computation and memory. We model the shape of the perturbation using parametric level-set approach (PaLS). We discuss novel computational strategies for reducing the computational cost based on a Krylov subspace approach for parameteric linear systems and a compression strategy for the parameter-to-observation map. We will demonstrate the validity of our approach by comparison with experiments.

  4. Megahertz streak-mode Fourier domain optical coherence tomography

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

    2011-01-01

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

  5. Optical diffraction tomography techniques for the study of cell pathophysiology

    Kim, Kyoohyun; Shin, Seungwoo; Lee, SangYun; Yang, Su-A; Park, YongKeun

    2016-01-01

    Three-dimensional imaging of biological cells is crucial for the investigation of cell biology, provide valuable information to reveal the mechanisms behind pathophysiology of cells and tissues. Recent advances in optical diffraction tomography (ODT) have demonstrated the potential for the study of various cells with its unique advantages of quantitative and label-free imaging capability. To provide insight on this rapidly growing field of research and to discuss its applications in biology and medicine, we present the summary of the ODT principle and highlight recent studies utilizing ODT with the emphasis on the applications to the pathophysiology of cells.

  6. Optical coherence tomography for glucose monitoring in blood

    Ullah, Hafeez; Hussain, Fayyaz; Ikram, Masroor

    2015-08-01

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

  7. Detection of bladder tumors using optical coherence tomography

    Pan, Yingtian; Xie, Tuqiang; Wang, Zhenguo

    2004-07-01

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

  8. Primate retina imaging with polarization-sensitive optical coherence tomography

    Ducros, Mathieu G.; Marsack, Jason D.; Rylander, H. Grady; Thomsen, Sharon L.; Milner, Thomas E.

    2001-12-01

    Polarization-sensitive optical coherence tomography (PSOCT) is applied to determine the depth-resolved polarization state of light backreflected from the eye. The birefringence of the retinal nerve fiber layer (RNFL) was observed and measured from PSOCT images recorded postmortem in a Rhesus monkey. An image-processing algorithm was developed to identify birefringent regions in acquired PSOCT retinal images and automatically determine the thickness of the RNFL. Values of the RNFL thickness determined from histology and PSOCT were compared. PSOCT may provide a new method to determine RNFL thickness and birefringence for glaucoma diagnostics.

  9. One step geometrical calibration method for optical coherence tomography

    Díaz Díaz, Jesús; Stritzel, Jenny; Rahlves, Maik; Majdani, Omid; Reithmeier, Eduard; Ortmaier, Tobias; Roth, Bernhard

    2016-01-01

    We present a novel one-step calibration methodology for geometrical distortion correction for optical coherence tomography (OCT). A calibration standard especially designed for OCT is introduced, which consists of an array of inverse pyramidal structures. The use of multiple landmarks situated on four different height levels on the pyramids allow performing a 3D geometrical calibration. The calibration procedure itself is based on a parametric model of the OCT beam propagation. It is validated by experimental results and enables the reduction of systematic errors by more than one order of magnitude. In future, our results can improve OCT image reconstruction and interpretation for medical applications such as real time monitoring of surgery.

  10. Modeling light–tissue interaction in optical coherence tomography systems

    Andersen, Peter E.; Jørgensen, Thomas Martini; Thrane, Lars; Tycho, Andreas; Yura, Harold T.

    Optical coherence tomography (OCT) performs high-resolution, cross-sectional tomographic imaging of the internal tissue microstructure by measuring backscattered or backreflected light. The scope of this chapter is to present analytical and numerical models that are able to describe light......-tissue interactions and its influence on the performance of OCT systems including multiple scattering effects in heterogeneous media. In general, these models, analytical as well as numerical, may serve as important tools for improving interpretation of OCT images and also serve as prerequisites for extraction of...

  11. Determination of optical scattering properties of highly-scattering media in optical coherence tomography images

    Levitz, D.; Thrane, L.; Frosz, Michael Henoch; Andersen, Peter E.; Andersen, C.B.; Andersson-Engels, S.; Valanciunaite, J.; Swartling, J.; Hansen, P.R.

    2004-01-01

    We developed a new algorithm that fits optical coherence tomography (OCT) signals as a function of depth to a general theoretical OCT model which takes into account multiple scattering effects. With use of this algorithm, it was possible to extract both the scattering coefficient and anisotropy...

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

    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.

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

    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.

  14. Optical tomography for measuring dose distribution in radiation therapy

    Kauppinen Matti

    2014-01-01

    Full Text Available The dosimetry is used to verify the dose magnitude with artificial samples (phantoms before giving the planned radiation therapy to the patient. Typically, dose distribution is measured only in a single point or on a two-dimensional matrix plane. New techniques of radiation therapy ensure more detailed planning of radiation dose distribution which will lead to the need of measuring the radiation dose distribution three-dimensionally. The gel dosimetry is used to indicate and determine the ionizing radiation three-dimensionally. The radiation causes changes in chemical properties of the gel. The radiation dose distribution is defined by measuring the chemical changes. A conventional method is the magnetic resonance imaging and a new possibility is optical computed tomography (optical-CT. The optical-CT is much cheaper and more practical than magnetic resonance imaging. In this project, an optical-CT based method device was built by aiming at low material costs and a simple realization. The constructed device applies the charge coupled device camera and fluorescent lamp technologies. The test results show that the opacity level of the radiated gel can be measured accurately enough. The imaging accuracy is restricted by the optical distortion, e. g. vignetting, of the lenses, the distortion of a fluorescent lamp as the light source and a noisy measuring environment.

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

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

    2005-07-01

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

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

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

    2000-02-01

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

  17. Optical coherence tomography a clinical and technical update

    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. Dynamic image reconstruction in time-resolved diffuse optical tomography

    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.

  19. Combined Endoscopic Optical Coherence Tomography and Laser Induced Fluorescence

    Barton, Jennifer K.; Tumlinson, Alexandre R.; Utzinger, Urs

    Optical coherence tomography (OCT) and laser-induced fluorescence (LIF) are promising modalities for tissue characterization in human patients and animal models. OCT detects coherently backscattered light, whereas LIF detects fluorescence emission of endogenous biochemicals, such as reduced nicotinamide adenine dinucleotide (NADH), flavin adenine dinucleotide (FAD), collagen, and fluorescent proteins, or exogenous substances such as cyanine dyes. Given the complementary mechanisms of contrast for OCT and LIF, the combination of the two modalities could potentially provide more sensitive and specific detection of disease than either modality alone. Sample probes for both OCT and LIF can be implemented using small diameter optical fibers, suggesting a particular synergy for endoscopic applications. In this chapter, the mechanisms of contrast and diagnostic capability for both OCT and LIF are briefly examined. Evidence of complementary capability is described. Example published combined OCT-LIF systems are reviewed, one successful commercial instrument is discussed, and example applications are provided.

  20. Performance of latex balloons for optical computed tomography

    Latex balloons filled with radiation sensitive hydrogels were evaluated as 3D dosimeters with optical computed tomography (CT) readout. Custom balloons, with less than 10 cm diameters, were made from latex sheets. Commercial, 13 cm diameter, clear balloons were investigated for larger volumes. Ferrous-xylenol orange and genipin gelatin gels selected for 1 and 30 Gy experiments, respectively. The thin stretched latex membrane allowed optical imaging to within 1 mm of the interior balloon edge. Reconstructed dose distributions demonstrated valid measurements to within 2 mm of the balloon surface. The rubber membrane provides a hybrid approach to deforming hydrogels. Uniform irradiation of a deformed gel resulted in a uniform dose being measured when scanned in the relaxed, initial balloon shape. The 13 cm diameter balloons were also effective and inexpensive vessels for hydrogels due to their high clarity, thinness and mechanical strength. Latex balloons represent an inexpensive method to obtain useful information from nearly the entire dosimeter volume.

  1. Thickness estimation with optical coherence tomography and statistical decision theory

    Huang, Jinxin; Yao, Jianing; Cirucci, Nick; Ivanov, Trevor; Rolland, Jannick P.

    2015-10-01

    Thickness estimation, which has a broad range of applications, plays an important role in the field of optical metrology. In this study, we investigate a new approachcombining optical coherence tomography (OCT) and statistical decision theoryfor thickness estimation. We first discussed and quantified the intensity noise of three commonly used broadband sources, a super-continuum source, a super-luminescent diode (SLD), and a swept source. Furthermore, a maximum-likelihood (ML) estimator was implemented to interpret the OCT raw data. Based on the mathematical model and the ML estimator, simulations were set up to investigate the impact of different broadband sources in OCT for a thickness estimation task. We then validated the theoretical framework with physical phantoms. Results demonstrate unbiased nanometer-class thickness estimates with the ML estimator. The framework can be potentially used for film and surface shape metrology.

  2. Imaging of collagen deposition disorders using optical coherence tomography

    Ring, H C; Mogensen, M; Hussain, A A; Steadman, N; Banzhaf, C; Themstrup, L; Jemec, G B

    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...

  3. Cell death monitoring using quantitative optical coherence tomography methods

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

    2011-03-01

    Cell death is characterized by a series of predictable morphological changes, which modify the light scattering properties of cells. We present a multi-parametric approach to detecting changes in subcellular morphology related to cell death using optical coherence tomography (OCT). Optical coherence tomography data were acquired from acute myeloid leukemia (AML) cells undergoing apoptosis over a period of 48 hours. Integrated backscatter (IB) and spectral slope (SS) were computed from OCT backscatter spectra and statistical parameters were extracted from a generalized gamma (GG) distribution fit to OCT signal intensity histograms. The IB increased by 2-fold over 48 hours with significant increases observed as early as 4 hours. The SS increased in steepness by 2.5-fold with significant changes at 12 hours, while the GG parameters were sensitive to apoptotic changes at 24 to 48 hours. Histology slides indicated nuclear condensation and fragmentation at 24 hours, suggesting the late scattering changes could be related to nuclear structure. A second series of measurements from AML cells treated with cisplatin, colchicine or ionizing radiation suggested that the GG parameters could potentially differentiate between modes of cell death. Distinct cellular morphology was observed in histology slides obtained from cells treated under each condition.

  4. Macular optical coherence tomography findings following blunt ocular trauma

    Oladiwura D

    2014-05-01

    Full Text Available Dilys Oladiwura,1 Lik Thai Lim,1 Elliott Yann Ah-kee,2 James Angus Scott31Tennent Institute of Ophthalmology, Gartnavel General Hospital (NHS Greater Glasgow and Clyde Trust, Glasgow, UK; 2University of Glasgow, Glasgow, UK; 3Falkirk Community Hospital (Forth Valley NHS Trust, Falkirk, UKAbstract: This case report describes the optical coherence tomography (OCT results of Berlins edema in a male subject following blunt ocular trauma from a soccer ball. A27-year-old male presented with blurred vision in his left eye following blunt trauma. On admission, he underwent a complete eye examination and an OCT of the macula. Fundoscopy revealed commotio retinae, observed as an abnormal cream-colored discoloration of the fovea. The OCT showed outer photoreceptor segment disruption, retinal pigment epithelium inter-digitation, and intra-retinal edema of the outer nuclear layer. Following initial management, a repeat OCT after3months showed near complete resolution. OCT can be a useful adjunct for monitoring the progress of Berlins edema secondary to blunt ocular trauma because Berlins edema may present similarly clinically to other ocular trauma, but can affect different layers of the retina depending on the type of injury to the eye.Keywords: Berlins edema, commotio retinae, optical coherence tomography, OCT, ocular trauma

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

    Li, Xiqi; Shi, Guohua; Zhang, Yudong

    2011-01-01

    The signal processing speed of spectral domain optical coherence tomography (SD-OCT) has become a bottleneck in many medical applications. Recently, a time-domain interpolation method was proposed. This method not only gets a better signal-to noise ratio (SNR) but also gets a faster signal processing time for the SD-OCT than the widely used zero-padding interpolation method. Furthermore, the re-sampled data is obtained by convoluting the acquired data and the coefficients in time domain. Thus, a lot of interpolations can be performed concurrently. So, this interpolation method is suitable for parallel computing. An ultra-high optical coherence tomography signal processing can be realized by using graphics processing unit (GPU) with computer unified device architecture (CUDA). This paper will introduce the signal processing steps of SD-OCT on GPU. An experiment is performed to acquire a frame SD-OCT data (400A-lines×2048 pixel per A-line) and real-time processed the data on GPU. The results show that it can be finished in 6.208 milliseconds, which is 37 times faster than that on Central Processing Unit (CPU).

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

    Li Xiqi; Shi Guohua; Zhang Yudong, E-mail: lixiqi@yahoo.cn [Laboratory on Adaptive Optics, Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209 (China)

    2011-01-01

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

  7. Optical coherence tomography for retinal imaging in multiple sclerosis

    Zimmermann H

    2014-12-01

    Full Text Available Hanna Zimmermann,1 Timm Oberwahrenbrock,1 Alexander U Brandt,1 Friedemann Paul,13 Jan Drr1,2 1NeuroCure Clinical Research Center, 2Clinical and Experimental Multiple Sclerosis Research Center, 3Department of Neurology, Charit Universittsmedizin 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

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

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

    2010-09-07

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

  9. Large-scale optical diffraction tomography for inspection of optical plastic lenses

    Kim, Kyoohyun; Park, YongKeun

    2015-01-01

    Herein is presented an optical diffraction tomography (ODT) technique for measuring 3-D refractive index (RI) maps of optical plastic lenses. A Mach-Zehnder interferometer was used to measure multiple complex optical fields of a plastic lens immersed in RI matching oil, at various rotational orientations. From this, ODT was used to reconstruct a 3-D RI distribution of the plastic lens with unprecedented RI sensitivity (dn = 4.21 x 10^-5) and high resolution (12.8 um). As a demonstration, 3-D RI distributions of a 2-mm-diameter borosilicate sphere and a 5-mm-diameter plastic lens

  10. Developing High-Density Diffuse Optical Tomography for Neuroimaging

    White, Brian Richard

    Clinicians who care for brain-injured patients and premature infants desire a bedside monitor of brain function. A decade ago, there was hope that optical imaging would be able to fill this role, as it combined fMRI's ability to construct cortical maps with EEG's portable, cap-based systems. However, early optical systems had poor imaging performance, and the momentum for the technique slowed. In our lab, we develop diffuse optical tomography (DOT), which is a more advanced method of performing optical imaging. My research has been to pioneer the in vivo use of DOT for advanced neuroimaging by (1) quantifying the advantages of DOT through both in silico simulation and in vivo performance metrics, (2) restoring confidence in the technique with the first retinotopic mapping of the visual cortex (a benchmark for fMRI and PET), and (3) creating concepts and methods for the clinical translation of DOT. Hospitalized patients are unable to perform complicated neurological tasks, which has motivated us to develop the first DOT methods for resting-state brain mapping with functional connectivity. Finally, in collaboration with neonatologists, I have extended these methods with proof-of-principle imaging of brain-injured premature infants. This work establishes DOT's improvements in imaging performance and readies it for multiple clinical and research roles.

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

    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.

  12. Optical coherence tomography demonstrating macular retinal nerve fiber thinning in advanced optic disc drusen

    Ali Hassan

    2014-01-01

    Full Text Available Optic disc drusen (ODD are extracellular proteinaceous excrescences in the optic nerve head. They enlarge over time and can cause damage to nerve fibers with resulting loss of visual field. The authors report a case of advanced ODD in which macular optical coherence tomography demonstrated retinal nerve fiber thinning. A single case report of a 42-year-old woman with known ODD presented to the eye clinic with worsening field of vision which was impacting on her daily life. The patient was subject to full ophthalmic examination as well as Goldmann visual field testing, optic disc photography and optical coherence tomography (OCT of both her optic discs and maculae. ODD although rare, can be visually devastating. No treatment is currently available however patients should be counseled about progressive nature of ODD and the potential for visual loss. OCT imaging of the maculae as well as optic discs may serve a role in monitoring the damage disc drusen cause to the eye.

  13. Macular spectral domain optical coherence tomography findings in Tanzanian endemic optic neuropathy.

    Kisimbi, John; Shalchi, Zaid; Mahroo, Omar A; Mhina, Celina; Sanyiwa, Anna J; Mabey, Denise; Mohamed, Moin; Plant, Gordon T

    2013-11-01

    Bilateral optic neuropathy in Dar es Salaam is now considered endemic and is estimated to affect 0.3-2.4% of young adults. The condition is characterized by a subacute bilateral loss of central vision of unknown aetiology. Findings of spectral domain optical coherence tomography have not previously been reported for these patients. All patients diagnosed with endemic optic neuropathy over a 2-year period at the Muhimbili National Hospital underwent spectral domain optical coherence tomography macular imaging. Scans were graded qualitatively for severity of retinal nerve fibre layer loss as well as the presence of microcystic macular changes, which have not previously been described in this condition. Of the 128 patients included (54.7% male; median age 20 years), severe retinal nerve fibre layer loss was found in 185 eyes (74.0%). There was full concordance in retinal nerve fibre layer thickness between the two eyes in 113 (91.1%) patients. Microcystic macular spaces were found in 16 (12.5%) patients and were bilateral in nine (7.0%) individuals. These changes were typically more prominent in the nasal than the temporal macula, predominantly involving the inner nuclear layer, and often occurred in an annular configuration that was evident on en face infra-red imaging, though not discernible on colour fundus photography or clinically. All patients with microcystic macular changes had severe thinning of the retinal nerve fibre layer (P = 0.02). Four patients in whom cystic spaces were demonstrated had sequential scans, and there was no detectable alteration in the configuration of these changes over a period of up to 16 months. This is the first study to document optical coherence tomography findings in endemic optic neuropathy. We have observed symmetrical severe loss of the caeco-central projection (papillomacular bundle) with otherwise well-preserved macular architecture. Also, we have observed microcystic retinal changes in a significant proportion of patients, which were associated with severe retinal nerve fibre layer loss. Similar changes have recently been reported from optical coherence tomography images of patients with multiple sclerosis, relapsing isolated optic neuritis, dominant optic atrophy, Leber's hereditary optic neuropathy and a patient with a chronic compressive optic neuropathy, supporting the hypothesis that this may be a non-specific phenomenon secondary to ganglion cell death. The correspondence of the changes to an annulus discernible on infra-red en face imaging, but not using other conventional retinal imaging techniques highlights the potential usefulness of this modality. PMID:24018312

  14. Three-dimensional imaging of xenograft tumors using optical computed and emission tomography

    Oldham, Mark; Sakhalkar, Harshad; Oliver, Tim; Wang, Ying Min; Kirkpatrick, John; Cao, Yiting; Badea, Cristian; Johnson, G. Allan; Dewhirst, Mark

    2006-01-01

    The physical basis and preliminary applications of optical computed tomography (optical-CT) and optical emission computed tomography (optical-ECT) are introduced, as new techniques with potential to provide unique 3D information on a variety of aspects of tumor structure and function. A particular focus here is imaging tumor micro-vasculature, and the spatial distribution of viable tumor cells, although the techniques have the potential for much wider application. The principle attractiveness...

  15. In-situ imaging of articular cartilage of the first carpometacarpal joint using co-registered optical coherence tomography and computed tomography

    Cernohorsky, Paul; de Bruin, Daniel M.; van Herk, Marcel; Bras, Johannes; Faber, Dirk J.; Strackee, Simon D.; van Leeuwen, Ton G.

    2012-06-01

    Conventional imaging modalities are unable to depict the early degeneration of articular cartilage in osteoarthritis, especially in small joints. Optical coherence tomography has previously been used successfully in high-resolution imaging of cartilage tissue. This pilot cadaver study demonstrates the use of intra-articular optical coherence tomography in imaging of articular cartilage of the first carpometacarpal joint, producing high resolution images of the articular surface in which cartilage thickness and surface characteristics were assessed. Findings on optical coherence tomography were confirmed with histology. Furthermore, co-registration of optical coherence tomography and computed tomography was used to accurately determine the scanned trajectory and reconstruct a true-scale image overlay.

  16. Spectral-Domain Optical Coherence Tomography and Fundus Autofluorescence Evaluation of Torpedo Maculopathy.

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

    2015-01-01

    The authors describe the spectral-domain optical coherence tomography and fundus autofluorescence findings in a case of torpedo maculopathy. Spectral-domain optical coherence tomography revealed loss or disruption of the retinal pigment epithelium and overlying disruption of the outer neurosensory retina. Fundus autofluorescence revealed reduced fundus autofluorescence of the lesion surrounded by a rim of increased fundus autofluorescence. PMID:26484432

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

    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.

  18. Simultaneous multiple-depths en-face optical coherence tomography using multiple signal excitation of acousto-optic deflectors.

    Zurauskas, Mantas; Rogers, John; Podoleanu, Adrian Gh

    2013-01-28

    We present a novel low-coherence interferometer configuration, equipped with acousto-optic deflectors that can be used to simultaneously acquire up to eight time domain optical coherence tomography en-face images. The capabilities of the configuration are evaluated in terms of depth resolution, signal to noise ratio and crosstalk. Then the configuration is employed to demonstrate simultaneous en-face optical coherence tomography imaging at five different depths in a specimen of armadillidium vulgare. PMID:23389175

  19. Optical diffraction tomography in an inhomogeneous background medium

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

  20. Metrological reliability of optical coherence tomography in biomedical applications

    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

  1. Compact piezoelectric transducer fiber scanning probe for optical coherence tomography.

    Zhang, Ning; Tsai, Tsung-Han; Ahsen, Osman O; Liang, Kaicheng; Lee, Hsiang-Chieh; Xue, Ping; Li, Xingde; Fujimoto, James G

    2014-01-15

    We developed a compact, optical fiber scanning piezoelectric transducer (PZT) probe for endoscopic and minimally invasive optical coherence tomography (OCT). Compared with previous forward-mount fiber designs, we present a reverse-mount design that achieves a shorter rigid length. The fiber was mounted at the proximal end of a quadruple PZT tube and scanned inside the hollow PZT tube to reduce the probe length. The fiber resonant frequency was 338 Hz using a 17-mm-long fiber. A 0.9 mm fiber deflection was achieved with a driving amplitude of 35 V. Using a GRIN lens-based optical design with a 1.3× magnification, a ∼6 μm spot was scanned over a 1.2 mm diameter field. The probe was encased in a metal hypodermic tube with a ∼25 mm rigid length and covered with a 3.2 mm outer diameter (OD) plastic sheath. Imaging was performed with a swept source OCT system based on a Fourier domain modelocked laser (FDML) light source at a 240 kHz axial scan rate and 8 μm axial resolution (in air). En face OCT imaging of skin in vivo and human colon ex vivo was demonstrated. PMID:24562102

  2. Fluorescence diffuse optical tomography: a wavelet-based model reduction

    Frassati, Anne; DaSilva, Anabela; Dinten, Jean-Marc; Georges, Didier

    2007-07-01

    Fluorescence diffuse optical tomography is becoming a powerful tool for the investigation of molecular events in small animal studies for new therapeutics developments. Here, the stress is put on the mathematical problem of the tomography, that can be formulated in terms of an estimation of physical parameters appearing as a set of Partial Differential Equations (PDEs). The Finite Element Method has been chosen here to resolve the diffusion equation because it has no restriction considering the geometry or the homogeneity of the system. It is nonetheless well-known to be time and memory consuming, mainly because of the large dimensions of the involved matrices. Our principal objective is to reduce the model in order to speed up the model computation. For that, a new method based on a multiresolution technique is chosen. All the matrices appearing in the discretized version of the PDEs are projected onto an orthonormal wavelet basis, and reduced according to the multiresolution method. With the first order resolution, this compression leads to the reduction of a factor 2x2 of the initial dimension, the inversion of the matrices is approximately 4 times faster. A validation study on a phantom was conducted to evaluate the feasibility of this reduction method.

  3. Histologic models for optical tomography and spectroscopy of tissues

    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.

  4. Radiographic, microcomputer tomography, and optical coherence tomography investigations of ceramic interfaces

    Sinescu, Cosmin; Negrutiu, Meda Lavinia; Ionita, Ciprian; Topala, Florin; Petrescu, Emanuela; Rominu, Roxana; Pop, Daniela Maria; Marsavina, Liviu; Negru, Radu; Bradu, Adrian; Rominu, Mihai; Podoleanu, Adrian Gh.

    2010-12-01

    Imagistic investigation of the metal-ceramic crowns and fixed partial prostheses represent a very important issue in nowadays dentistry. At this time, in dental office, it is difficult or even impossible to evaluate a metal ceramic crown or bridge before setting it in the oral cavity. The possibilities of ceramic fractures are due to small fracture lines or material defects inside the esthetic layers. Material and methods: In this study 25 metal ceramic crowns and fixed partial prostheses were investigated by radiographic method (Rx), micro computer tomography (MicroCT) and optical coherence tomography (OCT) working in Time Domain, at 1300 nm. The OCT system contains two interferometers and one scanner. For each incident analysis a stuck made of 100 slices was obtain. These slices were used in order to obtain a 3D model of the ceramic interface. Results: RX and MicroCT are very powerful instruments that provide a good characterization of the dental construct. It is important to observe the reflections due to the metal infrastructure that could affect the evaluation of the metal ceramic crowns and bridges. The OCT investigations could complete the imagistic evaluation of the dental construct by offering important information when it is need it.

  5. Optical coherence tomography of the epidermal sulfakrilate surface strippings

    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 (ОСТ 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.

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

    Mogensen, Mette; Thrane, Lars; Jørgensen, Thomas Martini; Andersen, Peter E.; Jemec, G.B.E.

    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 μm. 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...

  7. Phenotyping transgenic embryonic murine hearts using optical coherence tomography

    Jenkins, Michael W.; Patel, Pankti; Deng, Huayun; Montano, Monica M.; Watanabe, Michiko; Rollins, Andrew M.

    2007-04-01

    We used optical coherence tomography (OCT) to characterize the morphological phenotype of embryonic murine hearts discerning hexamethylene-bis-acetamide-inducible protein 1 (HEXIM1) mutants from their wild-type littermates. At E12.5 and E13.5 murine embryos were excised from the mother, the hearts were removed, and 3D OCT data sets were obtained from each heart in the litter. Next, we segmented the morphological borders to obtain cavity volumes and wall thicknesses. The mutant hearts exhibited increased ventricular chamber volume and decreased compact myocardium wall thickness when compared with their wild-type littermates. Also, the E13.5 HEXIM1 -/- embryo was distinguished by morphological asymmetry (underdeveloped left side).

  8. Megahertz streak-mode Fourier domain optical coherence tomography.

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

    2011-06-01

    Here we present an ultrahigh-speed Fourier-domain optical coherence tomography (OCT) that records the OCT spectrum in streak mode with a high-speed area scan camera, which allows higher OCT imaging speed than can be achieved with a line-scan camera. Unlike parallel OCT techniques that also use area scan cameras, the conventional single-mode fiber-based point-scanning mechanism is retained to provide a confocal gate that rejects multiply scattered photons from the sample. When using a 1000 Hz resonant scanner as the streak scanner, 1,016,000 A-scans have been obtained in 1 s. This method's effectiveness has been demonstrated by recording in vivo OCT-image sequences of embryonic chick hearts at 1000 frames/s. In addition, 2-megahertz OCT data have been obtained with another high speed camera. PMID:21721817

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

    Ring, H.C.; Hansen Stamp, I.M.; Jemec, G.B.E.

    2012-01-01

    Aim: To investigate the presentation of a patch-stage cutaneous T-cell lymphoma (CTCL) using optical coherence tomography (OCT). Methods: A patient with a patch caused by CTCL was photographed digitally, OCT-scanned and biopsied. A normal skin area adjacent to the patch was OCT-scanned for.......13 mm. A good immediate correlation was found between histology and OCT imaging of the sample. Conclusion: The aetiology of the elongated structures is thought to be lymphomatous infiltrates. Similar findings have been described in ocular lymphoma and may therefore be an important characteristic of...... cutaneous lymphoma. It may further be speculated that the differences in OCT images may reflect the biological behaviour of the infiltrate. This observation therefore suggests that OCT imaging may be a relevant tool for the in vivo investigation of mycosis fungoides and other CTCLs, but in order to verify...

  10. Toward an automated method for optical coherence tomography characterization

    Strupler, Mathias; Beckley, Amber M.; Benboujja, Fouzi; Dubois, Sylvain; Noiseux, Isabelle; Mermut, Ozzy; Bouchard, Jean-Pierre; Boudoux, Caroline

    2015-12-01

    With the increasing use of optical coherence tomography (OCT) in biomedical applications, robust yet simple methods for calibrating and benchmarking a system are needed. We present here a procedure based on a calibration object complemented with an algorithm that analyzes three-dimensional OCT datasets to retrieve key characteristics of an OCT system. The calibration object combines state-of-the-art tissue phantom material with a diamond-turned aluminum multisegment mirror. This method is capable of determining rapidly volumetric field-of-view, axial resolution, and image curvature. Moreover, as the phantom material mimics biological tissue, the system's signal and noise levels can be evaluated in conditions close to biological experiments. We believe this method could improve OCT quantitative data analysis and help OCT data comparison for longitudinal or multicenter studies.

  11. Pre-seizure state identified by diffuse optical tomography

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

    2014-01-01

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

  12. Statistical analysis of motion contrast in optical coherence tomography angiography

    Cheng, Yuxuan; Guo, Li; Pan, Cong; Lu, Tongtong; Hong, Tianyu; Ding, Zhihua; Li, Peng

    2015-11-01

    Optical coherence tomography angiography (Angio-OCT), mainly based on the temporal dynamics of OCT scattering signals, has found a range of potential applications in clinical and scientific research. Based on the model of random phasor sums, temporal statistics of the complex-valued OCT signals are mathematically described. Statistical distributions of the amplitude differential and complex differential Angio-OCT signals are derived. The theories are validated through the flow phantom and live animal experiments. Using the model developed, the origin of the motion contrast in Angio-OCT is mathematically explained, and the implications in the improvement of motion contrast are further discussed, including threshold determination and its residual classification error, averaging method, and scanning protocol. The proposed mathematical model of Angio-OCT signals can aid in the optimal design of the system and associated algorithms.

  13. Optical Coherence Tomography and Raman Spectroscopy of the retina

    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.

  14. Imaging port wine stains by fiber optical coherence tomography

    Zhao, Shiyong; Gu, Ying; Xue, Ping; Guo, Jin; Shen, Tingmei; Wang, Tianshi; Huang, Naiyan; Zhang, Li; Qiu, Haixia; Yu, Xin; Wei, Xunbin

    2010-05-01

    We develop a fiber optical coherence tomography (OCT) system in the clinical utility of imaging port wine stains (PWS). We use our OCT system on 41 patients with PWS to document the difference between PWS skin and contralateral normal skin. The system, which operates at 4 frames/s with axial and transverse resolutions of 10 and 9 μm, respectively, in the skin tissue, can clearly distinguish the dilated dermal blood vessels from normal tissue. We present OCT images of patients with PWS and normal human skin. We obtain the structural parameters, including epidermal thickness and diameter and depth of dilated blood vessels. We demonstrate that OCT may be a useful tool for the noninvasive imaging of PWS. It may help determine the photosensitizer dose and laser parameters in photodynamic therapy for treating port wine stains.

  15. Correlation between optical coherence tomography images and histology of pigskin

    Kuranov, Roman; Sapozhnikova, Veronika; Prough, Donald; Cicenaite, Inga; Esenaliev, Rinat

    2007-04-01

    Noninvasive imaging techniques such as optical coherence tomography (OCT) are being widely used for early diagnostics of a variety of pathologies. Traditional tissue preparation for histological evaluation alters the dimensions of histological images such that differences between the dimensions of histologic and OCT images can be as great as 2.5-fold. This discrepancy complicates quantitative interpretation of OCT images. Here we used a steel ring sewn to the pigskin to avoid tissue deformation due to excision and fixation and used a surgical suture as a fixed tissue marker. With these techniques, we achieved good correlation between OCT and histological images with differences of less than 10%. The resulting method significantly enhances the diagnostic capabilities of the OCT technique.

  16. Autofocus Algorithm for Dispersion Correction in Optical Coherence Tomography

    Marks, Daniel L.; Oldenburg, Amy L.; Reynolds, J. Joshua; Boppart, Stephen A.

    2003-06-01

    Practical clinical optical coherence tomography (OCT) systems require automatic tools for identifying and correcting flaws in OCT images. One type of flaw is the loss of image detail owing to the dispersion of the medium, which in most cases is unknown. We present an autofocus algorithm for estimating the delay line and material dispersion from OCT reflectance data, integrating a previously presented dispersion compensation algorithm to correct the data. The algorithm is based on minimizing the Renyi entropy of the corrected axial-scan image, which is a contrast-enhancement criterion. This autofocus algorithm can be used in conjunction with a high-speed, digital-signal-processor-based OCT acquisition system for rapid image correction.

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

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

  18. Voxel Based Morphometry in Optical Coherence Tomography: Validation & Core Findings

    Antony, Bhavna J.; Chen, Min; Carass, Aaron; Jedynak, Bruno M.; Al-Louzi, Omar; Solomon, Sharon D.; Saidha, Shiv; Calabresi, Peter A.; Prince, Jerry L.

    2016-01-01

    Optical coherence tomography (OCT) of the human retina is now becoming established as an important modality for the detection and tracking of various ocular diseases. Voxel based morphometry (VBM) is a long standing neuroimaging analysis technique that allows for the exploration of the regional differences in the brain. There has been limited work done in developing registration based methods for OCT, which has hampered the advancement of VBM analyses in OCT based population studies. Following on from our recent development of an OCT registration method, we explore the potential benefits of VBM analysis in cohorts of healthy controls (HCs) and multiple sclerosis (MS) patients. Specifically, we validate the stability of VBM analysis in two pools of HCs showing no significant difference between the two populations. Additionally, we also present a retrospective study of age and sex matched HCs and relapsing remitting MS patients, demonstrating results consistent with the reported literature while providing insight into the retinal changes associated with this MS subtype.

  19. Speckle reduction in parallel optical coherence tomography by spatial compounding

    Huang, Bingjie; Bu, Peng; Wang, Xiangzhao; Nan, Nan; Guo, Xin

    2013-02-01

    In this paper, we propose a novel method for speckle reduction by combining spatial compounding technique with parallel Fourier-domain optical coherence tomography (FDOCT). Through a two-dimensional (2-D) CCD camera, multiple spectral interference fringes for a single lateral point are acquired with adjacent pixels in parallel detection plane simultaneously. By compounding these spatial-resolved images, we can obtain a speckle-suppressed B-scan tomogram in a single shot without sacrificing axial resolution and imaging speed. The principle of our method is demonstrated by imaging a shrimp's telson in vivo and a pearl. A signal-to-noise ratio improvement close to a factor of two was achieved by averaging four spatial-resolved FDOCT images.

  20. Macular optical coherence tomography findings following blunt ocular trauma

    Oladiwura, Dilys; Lim, Lik Thai; Ah-kee, Elliott Yann; Scott, James Angus

    2014-01-01

    This case report describes the optical coherence tomography (OCT) results of Berlins edema in a male subject following blunt ocular trauma from a soccer ball. A 27-year-old male presented with blurred vision in his left eye following blunt trauma. On admission, he underwent a complete eye examination and an OCT of the macula. Fundoscopy revealed commotio retinae, observed as an abnormal cream-colored discoloration of the fovea. The OCT showed outer photoreceptor segment disruption, retinal pigment epithelium inter-digitation, and intra-retinal edema of the outer nuclear layer. Following initial management, a repeat OCT after 3 months showed near complete resolution. OCT can be a useful adjunct for monitoring the progress of Berlins edema secondary to blunt ocular trauma because Berlins edema may present similarly clinically to other ocular trauma, but can affect different layers of the retina depending on the type of injury to the eye. PMID:24899795

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

    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 (μt), 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 (pattenuation demonstrated a capability for monitoring changes of enamel lesions during remineralization. PMID:23563920

  2. Statistical analysis of motion contrast in optical coherence tomography angiography

    Cheng, Yuxuan; Pan, Cong; Lu, Tongtong; Hong, Tianyu; Ding, Zhihua; Li, Peng

    2015-01-01

    Optical coherence tomography angiography (Angio-OCT), mainly based on the temporal dynamics of OCT scattering signals, has found a range of potential applications in clinical and scientific researches. In this work, based on the model of random phasor sums, temporal statistics of the complex-valued OCT signals are mathematically described. Statistical distributions of the amplitude differential (AD) and complex differential (CD) Angio-OCT signals are derived. The theories are validated through the flow phantom and live animal experiments. Using the model developed in this work, the origin of the motion contrast in Angio-OCT is mathematically explained, and the implications in the improvement of motion contrast are further discussed, including threshold determination and its residual classification error, averaging method, and scanning protocol. The proposed mathematical model of Angio-OCT signals can aid in the optimal design of the system and associated algorithms.

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

    Mogensen, Mette; Thrane, Lars; Jrgensen, Thomas Martini; Andersen, Peter E.; Jemec, G.B.E.

    2009-01-01

    , 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......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...... 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...

  4. Evaluation of microfluidic channels with optical coherence tomography

    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.

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

    Willerslev, Anne; Li, Xiao Qiang; Cordtz, Peter; Munch, Inger C; Larsen, Michael

    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...... 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 reflectivity faded 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...

  6. Virtual histology of the human heart using optical coherence tomography

    Ambrosi, Christina M.; Moazami, Nader; Rollins, Andrew M.; Efimov, Igor R.

    2009-09-01

    Optical coherence tomography (OCT) allows for the visualization of micron-scale structures within nontransparent biological tissues. For the first time, we demonstrate the use of OCT in identifying components of the cardiac conduction system and other structures in the explanted human heart. Reconstructions of cardiac structures up to 2 mm below the tissue surface were achieved and validated with Masson Trichrome histology in atrial, ventricular, sinoatrial nodal, and atrioventricular nodal preparations. The high spatial resolution of OCT provides visualization of cardiac fibers within the myocardium, as well as elements of the cardiac conduction system; however, a limiting factor remains its depth penetration, demonstrated to be ~2 mm in cardiac tissues. Despite its currently limited imaging depth, the use of OCT to identify the structural determinants of both normal and abnormal function in the intact human heart is critical in its development as a potential aid to intracardiac arrhythmia diagnosis and therapy.

  7. Evaluation of microfluidic channels with optical coherence tomography

    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.

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

    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.

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

    Xu, Xiangqun; Yu, Lingfeng; Chen, Zhongping

    2008-01-01

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

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

    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 mirrors vibration angle of approximately 10

  11. Multiple scattering and intensity fluctuations in optical coherent tomography of randomly inhomogeneous media

    An expression for signal intensity fluctuations in optical coherent tomography has been obtained for the first time in the framework of the theory of the multiple scattering of low-coherent optical radiation in a random medium. The contribution of the multiple scattering of low-coherent radiation backscattered from a randomly inhomogeneous layer, as well as the speckles of the interference component in optical coherent tomography, has been calculated

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

    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.

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

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

    2012-02-01

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

  14. Morphological phenotyping of mouse hearts using optical coherence tomography

    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.

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

    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.

  16. Polarization-sensitive optical projection tomography for muscle fiber imaging.

    Fang, Mengjie; Dong, Di; Zeng, Chaoting; Liang, Xiao; Yang, Xin; Arranz, Alicia; Ripoll, Jorge; Hui, Hui; Tian, Jie

    2016-01-01

    Optical projection tomography (OPT) is a tool used for three-dimensional imaging of millimeter-scale biological samples, with the advantage of exhibiting isotropic resolution typically in the micron range. OPT can be divided into two types: transmission OPT (tOPT) and emission OPT (eOPT). Compared with eOPT, tOPT discriminates different tissues based on their absorption coefficient, either intrinsic or after specific staining. However, it fails to distinguish muscle fibers whose absorption coefficients are similar to surrounding tissues. To circumvent this problem, in this article we demonstrate a polarization sensitive OPT system which improves the detection and 3D imaging of muscle fibers by using polarized light. We also developed image acquisition and processing protocols that, together with the system, enable the clear visualization of muscles. Experimental results show that the muscle fibers of diaphragm and stomach, difficult to be distinguished in regular tOPT, were clearly displayed in our system, proving its potential use. Moreover, polarization sensitive OPT was fused with tOPT to investigate the stomach tissue comprehensively. Future applications of polarization sensitive OPT could be imaging other fiber-like structures such as myocardium or other tissues presenting high optical anisotropy. PMID:26752330

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

    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...

  18. Vascular wall stress during intravascular optical coherence tomography imaging

    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.

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

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

  20. Assessment of tissue optical clearing as a function of glucose concentration using optical coherence tomography

    Sudheendran, Narendran; Mohamed, Mohamed; Ghosn, Mohamad G.; Tuchin, Valery V.; Larin, Kirill V.

    2011-03-01

    In imaging of turbid biological samples using optical techniques, optical clearing methods can compensate for the lack of light penetration due to strong attenuation. The addition of optical clearing agents into scattering media increases the optical homogeneity of the sample and reduces its turbidity, allowing for the increased light penetration. In this study we investigated the extent of optical clearing in porcine skin by utilizing various concentrations of glucose solution. A goldplated mirror was fixed beneath the tissue and percentage clearing was determined by measuring the change in intensity of optical coherence tomography light returning from the mirror over time. A ratio of percentage clearing per tissue thickness for 10%, 30%, and 50% glucose was determined to be to be (4.7 +/- 1.6%) mm-1 (n = 6), (10.6 +/- 2.0%) mm-1 (n = 7), and (21.8 +/- 2.2%) mm-1 (n = 5), respectively. Although the extent of optical clearing in porcine skin was more significant for 50% glucose, the osmotic stress on the sample can cause considerable morphology change, thus a suitable concentration must be chosen for particular circumstances.

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

    Edward Wylegala

    2013-01-01

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

  2. Optical tomography with structured illumination using the three-dimensional FN method

    Machida, Manabu

    2015-01-01

    One way of formulating optical tomography is to use the Born series, which is given by the Green's function for the homogeneous medium. The three-dimensional FN method is a numerical method of obtaining the specific intensity of the radiative transport equation expressed as a superposition of three-dimensional singular eigenfunctions. In this paper, we compute the Green's function for the radiative transport equation using the three-dimensional FN method without making diffusion approximation. To illustrate the present formulation of optical tomography, we consider optical tomography with structured illumination.

  3. Fiber-based polarization-sensitive optical coherence tomography

    Park, Boris Hyle

    Polarization-sensitive optical coherence tomography (PS-OCT) is an interferometric technique capable of non-invasive depth-resolved imaging of the polarization properties of biological tissue that has shown great promise for a wide variety of clinical applications. Furthering these applications almost necessitate fiber-based implementation; however, optical fiber can induce an unknown birefringence that complicates determination of sample polarization properties. In principle, cumulative sample polarization properties can be determined by comparison of the polarization states reflected from the surface of the sample to those reflected from some depth within the sample for two unique incident polarization states optimally separated by 90° in a Poincare sphere representation. Three different solutions capable of determining sample polarization properties using a fiber-based PS-OCT system with the unrestricted use of optical fiber and non-diattenuating fiber components are presented. First, a simple Stokes vector-based method assuming no sample diattenuation is discussed, and applied to an in vivo animal study demonstrating a correlation between histological burn depth and PS-OCT derived measurements. This computationally-efficient method has been used in a number of clinical studies to date. Second, a vector-based method that additionally determines sample diattenuation in a separate step is presented. Third, a Jones matrix-based analysis that simultaneously determines the amounts and common optic axis for sample birefringence and diattenuation is described, as are fundamental ambiguities in optic axis determination. The latter two methods were experimentally verified by comparison with independent measurements, and demonstrate the relative importance of diattenuation versus birefringence to the angular displacement of Stokes vectors in a Poincare sphere representation. Practical implementation of PS-OCT in a clinical setting also demands high acquisition speed and real-time display. Two fiber-based systems capable of high acquisition speeds and real-time display of simultaneous tissue structure, birefringence, and flow images are presented. The first system, based on traditional time-domain technology, has been used in a number of clinical studies to date, and even been adapted for endoscopic applications. Finally, fundamental limitations on the accuracy of phase determination as functions of signal-to-noise ratio and lateral scan speed are described and their relative contributions are compared. The consequences of phase accuracy are discussed for PS-OCT measurements.

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

    Tilman Schmoll

    2015-09-01

    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 01.jpg 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 01.jpg 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.

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

    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.

  6. Adaptive optics optical coherence tomography for in vivo mouse retinal imaging

    Jian, Yifan; Zawadzki, Robert J.; Sarunic, Marinko V.

    2013-05-01

    Small animal models of retinal diseases are important to vision research, and noninvasive high resolution in vivo rodent retinal imaging is becoming an increasingly important tool used in this field. We present a custom Fourier domain optical coherence tomography (FD-OCT) instrument for high resolution imaging of mouse retina. In order to overcome aberrations in the mouse eye, we incorporated a commercial adaptive optics system into the sample arm of the refractive FD-OCT system. Additionally, a commercially available refraction canceling lens was used to reduce lower order aberrations and specular back-reflection from the cornea. Performance of the adaptive optics (AO) system for correcting residual wavefront aberration in the mice eyes is presented. Results of AO FD-OCT images of mouse retina acquired in vivo with and without AO correction are shown as well.

  7. Large-scale optical diffraction tomography for inspection of optical plastic lenses.

    Kim, Kyoohyun; Yoon, Jonghee; Park, YongKeun

    2016-03-01

    Herein is presented an optical diffraction tomography (ODT) technique for measuring 3-D refractive index (RI) maps of optical plastic lenses. A Mach-Zehnder interferometer was used to measure multiple complex optical fields of a plastic lens immersed in RI-matching oil at various rotational orientations. From this, ODT was used to reconstruct a 3-D RI distribution of the plastic lens with unprecedented RI sensitivity (Δn=4.21×10-5) and high resolution (12.8 μm). As a demonstration, 3-D RI distributions of a 2 mm-diameter borosilicate sphere and a 5 mm-diameter plastic lens were reconstructed. Defects in the lens, generated by pulsed laser ablation, were also detected using the present method. PMID:26974084

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

    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 m (range 50.2 to 98.5 at the fovea, 6.5 24.3 m (range ?65.8 to 90.2 temporally, 0.5 22.3 m (range 27.1 to 82.5 nasally, 9.7 21.7 m (range 40.1 to 60.1 superiorly, and 1.4 25.5 m (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

  9. Optical coherence tomography monitoring of enhanced skin optical clearing in rats in vivo.

    Genina, Elina A; Bashkatov, Alexey N; Kolesnikova, Ekaterina A; Basko, Marina V; Terentyuk, Georgy S; Tuchin, Valery V

    2014-02-01

    A comparative study of physical, chemical, and combined enhancement of transdermal transport of optical clearing agents (OCAs) is presented. As a physical enhancer of diffusivity, ultrasound (US) with a frequency 1 MHz and a power 1.1 W in the continuous mode was used, and dimethyl sulfoxide (DMSO) was used as a chemical enhancer. OCA (glycerol and polyethylene glycol-400 in equal proportion) was topically applied to the rat skin in vivo as alone or as together with the enhancers. Monitoring of skin optical clearing was implemented using an optical coherence tomography. The results have shown that the attenuation coefficient of intact skin dermis after the application of US-DMSO-OCA, US-OCA (both for 4 min), and DMSO-OCA (for 20 min) combinations decreased approximately by 31%, 19%, and 5%, respectively, while OCA alone did not induce a noticeable clearing effect for 20 min. Control skin sites with removed epidermis were used for modeling the upper limit of dermis optical clearing, i.e., maximal degree of optical clearing, by using the studied enhancers. They demonstrated that the attenuation coefficient decreases by 32%, 30%, 17%, and 16% at the action of US-DMSO-OCA, US-OCA, DMSO-OCA, and OCA, respectively. It can be concluded that US-DMSO-OCA combination only allowed reaching the upper limit of skin optical clearing. PMID:24105426

  10. Imaging of subchondral bone by optical coherence tomography upon optical clearing of articular cartilage.

    Bykov, Alexander; Hautala, Tapio; Kinnunen, Matti; Popov, Alexey; Karhula, Sakari; Saarakkala, Simo; Nieminen, Miika T; Tuchin, Valery; Meglinski, Igor

    2016-03-01

    Optical clearing is an effective method to reduce light scattering of biological tissues that provides significant enhancement of light penetration into the biological tissues making non-invasive diagnosis more feasible. In current report Optical Coherence Tomography (OCT) in conjunction with optical clearing is applied for assessment of deep cartilage layers and cartilage-bone interface. The solution of Iohexol in water has been used as an optical clearing agent. The cartilage-bone boundary becomes visible after 15 min of optical clearing that enabling non-invasive estimation of its roughness: Sa  = 10 ± 1 µm. The results show that for 0.9 mm thick cartilage optical clearing is stopped after 50 min with an increase of refractive index from 1.386 ± 0.008 to 1.510 ± 0.009. Current approach enables more reliable detection of arthroscopically inaccessible regions, including cartilage-bone boundary and subchondral bone, and potentially improves accuracy of the osteoarthritis diagnosis. PMID:26097171

  11. Region-of-interest diffuse optical tomography system

    Saikia, Manob Jyoti; Kanhirodan, Rajan

    2016-01-01

    Diffuse optical tomography (DOT) using near-infrared light is a promising tool for non-invasive imaging of deep tissue. This technique is capable of quantitative reconstruction of absorption (μa) and scattering coefficient (μs) inhomogeneities in the tissue. The rationale for reconstructing the optical property map is that the absorption coefficient variation provides diagnostic information about metabolic and disease states of the tissue. The aim of DOT is to reconstruct the internal tissue cross section with good spatial resolution and contrast from noisy measurements non-invasively. We develop a region-of-interest scanning system based on DOT principles. Modulated light is injected into the phantom/tissue through one of the four light emitting diode sources. The light traversing through the tissue gets partially absorbed and scattered multiple times. The intensity and phase of the exiting light are measured using a set of photodetectors. The light transport through a tissue is diffusive in nature and is modeled using radiative transfer equation. However, a simplified model based on diffusion equation (DE) can be used if the system satisfies following conditions: (a) the optical parameter of the inhomogeneity is close to the optical property of the background, and (b) μs of the medium is much greater than μa (μs > > μa). The light transport through a highly scattering tissue satisfies both of these conditions. A discrete version of DE based on finite element method is used for solving the inverse problem. The depth of probing light inside the tissue depends on the wavelength of light, absorption, and scattering coefficients of the medium and the separation between the source and detector locations. Extensive simulation studies have been carried out and the results are validated using two sets of experimental measurements. The utility of the system can be further improved by using multiple wavelength light sources. In such a scheme, the spectroscopic variation of absorption coefficient in the tissue can be used to arrive at the oxygenation changes in the tissue.

  12. The use of optical coherence tomography in maxillofacial surgery

    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.

  13. Investigation of murine vasodynamics by Fourier domain optical coherence tomography

    Meißner, Sven; Müller, Gregor; Walther, Julia; Krüger, Alexander; Cuevas, Maximiliano; Eichhorn, Birgit; Ravens, Ursula; Morawietz, Henning; Koch, Edmund

    2007-07-01

    In vivo imaging of blood vessels obtain useful insights in characterizing the dynamics of vasoconstriction and vasodilation. Fourier domain optical Coherence Tomography (FD-OCT) imaging technique permits in vivo investigation of blood vessels in their anatomical context without preparation traumata by temporal resolved image stacks. OCT is an optical, contact less imaging technique based on Michelson interferometry of short coherent near infrared light. Particularly by the possibility of a contact-less measurement and the high axial resolution up to 10 microns OCT is superior to an investigation by ultra sound measurement. Furthermore we obtain a high time resolution of vessel dynamic measurements with the used Fourier domain OCT-system by a high A-scan rate [1,22kHz]. In this study the model of saphenous artery was chosen for analyzing function and dynamics. The arteria saphena in the mouse is a suitable blood vessel due to the small inner diameter, a sensitive response to vasoactive stimuli and an advantageous anatomically position. Male wild type mice (C57BL/6) at the age of 8 weeks were fed control or high-fat diet for 10 weeks before analyzing the vasodynamics. The blood vessel was stimulated by dermal application of potassium to induce vasoconstriction or Sodium-Nitroprusside (SNP) to induce vasodilation. The morphology of the a. saphena and vein was determined by 3D image stacks. Time series (72 seconds, 300x512 pixel per frame) of cross-sectional images were analysed using semi automatic image processing software. Time course of dynamic parameters of the vessel was measured.

  14. Integral ceramic superstructure evaluation using time domain optical coherence tomography

    Sinescu, Cosmin; Bradu, Adrian; Topala, Florin I.; Negrutiu, Meda Lavinia; Duma, Virgil-Florin; Podoleanu, Adrian G.

    2014-02-01

    Optical Coherence Tomography (OCT) is a non-invasive low coherence interferometry technique that includes several technologies (and the corresponding devices and components), such as illumination and detection, interferometry, scanning, adaptive optics, microscopy and endoscopy. From its large area of applications, we consider in this paper a critical aspect in dentistry - to be investigated with a Time Domain (TD) OCT system. The clinical situation of an edentulous mandible is considered; it can be solved by inserting 2 to 6 implants. On these implants a mesostructure will be manufactured and on it a superstructure is needed. This superstructure can be integral ceramic; in this case materials defects could be trapped inside the ceramic layers and those defects could lead to fractures of the entire superstructure. In this paper we demonstrate that a TD-OCT imaging system has the potential to properly evaluate the presence of the defects inside the ceramic layers and those defects can be fixed before inserting the prosthesis inside the oral cavity. Three integral ceramic superstructures were developed by using a CAD/CAM technology. After the milling, the ceramic layers were applied on the core. All the three samples were evaluated by a TD-OCT system working at 1300 nm. For two of the superstructures evaluated, no defects were found in the most stressed areas. The third superstructure presented four ceramic defects in the mentioned areas. Because of those defects the superstructure may fracture. The integral ceramic prosthesis was send back to the dental laboratory to fix the problems related to the material defects found. Thus, TD-OCT proved to be a valuable method for diagnosing the ceramic defects inside the integral ceramic superstructures in order to prevent fractures at this level.

  15. Cystoid macular edema diagnosed with optical coherent tomography in patients operated on from cataract

    Refers frequency of cystoid macular edema diagnosed with optical coherence tomography in patients operated on from senile cataract at 'Ramon Pando Ferrer' Cuban Institute of Ophthalmology in the period from December 2006 to February 2007

  16. Characterization of dynamic physiology of the bladder by optical coherence tomography

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

    2012-03-01

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

  17. Heartbeat OCT: in vivo intravascular megahertz-optical coherence tomography.

    Wang, Tianshi; Pfeiffer, Tom; Regar, Evelyn; Wieser, Wolfgang; van Beusekom, Heleen; Lancee, Charles T; Springeling, Geert; Krabbendam, Ilona; van der Steen, Antonius F W; Huber, Robert; van Soest, Gijs

    2015-12-01

    Cardiac motion artifacts, non-uniform rotational distortion and undersampling affect the image quality and the diagnostic impact of intravascular optical coherence tomography (IV-OCT). In this study we demonstrate how these limitations of IV-OCT can be addressed by using an imaging system that we called "Heartbeat OCT", combining a fast Fourier Domain Mode Locked laser, fast pullback, and a micromotor actuated catheter, designed to examine a coronary vessel in less than one cardiac cycle. We acquired in vivo data sets of two coronary arteries in a porcine heart with both Heartbeat OCT, working at 2.88 MHz A-line rate, 4000 frames/s and 100 mm/s pullback speed, and with a commercial system. The in vivo results show that Heartbeat OCT provides faithfully rendered, motion-artifact free, fully sampled vessel wall architecture, unlike the conventional IV-OCT data. We present the Heartbeat OCT system in full technical detail and discuss the steps needed for clinical translation of the technology. PMID:26713214

  18. Determination of dental decay rates with optical coherence tomography

    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 μW in the sample arm, and spectral characteristics allowing 23 μm of axial resolution. The images were produced with lateral scans step of 10 μm 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 μm to 230 μm (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

  19. Imaging natural occlusal caries lesions with optical coherence tomography

    Douglas, Shane M.; Fried, Daniel; Darling, Cynthia L.

    2010-02-01

    Several studies have demonstrated that polarization-sensitive optical coherence tomography (PS-OCT) can be used to nondestructively measure the severity of demineralization in the important occlusal surfaces. The purpose of this study was to assess the potential of PS-OCT and OCT methods for the measurement of the depth of natural occlusal carious lesions. Teeth were screened for potential occlusal lesions using near infrared imaging (NIR). A PS-OCT system operating at 1310-nm was used to acquire polarization resolved images of the area of interest on the occlusal surface. The teeth were serial sectioned to 200 μm thickness and examined with polarized light microscopy (PLM) and Transverse Microradiography (TMR) for comparison. The lesion depth measured nondestructively with PS-OCT was compared to the lesion depth measured with PLM and TMR to assess the performance of these methods and determine if polarization sensitivity is required. The lesion depth measured using OCT correlated well with the lesion depths measured with TMR and PLM. Although polarization sensitivity provided better contrast it was not necessary to have polarization sensitivity to identify deep occlusal lesions.

  20. Benefits of optical coherence tomography for imaging of skin diseases

    Utz S.R.

    2015-09-01

    Full Text Available Aim: working out the methods of visualization of information obtained during optical coherent tomography in normal skin and in series of inflammatory disorders. Materials and Methods. OCS1300SS (made in Thorlabs, USA was used in which the source of emission of radiation was a super-luminiscent diode with mean wavelength of 1325 nm. 12 patients with different skin conditions and 5 virtually healthy volunteers were examined with ОСТ procedure in OPD and IPD settings. High resolution USG numerical system DUB (TPM GmbH, Germany was used for comparative USG assessment. Results. ОСТ demonstrated considerably more detailed picture of the objects scanned compared to USG investigation. Image obtained with the help of ОСТ contains vital information about sizes of macro-morphological elements, status of vascular elements and their density in different depths of the skin. Conclusion. Additional results obtained from ОСТ of the skin lesions in plane section improves attraction for ОСТ in practical dermatology.

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

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

  2. Methods for monitoring erosion using optical coherence tomography

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

    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 potentially be used in vivo were investigated. The first approach is to measure the remaining enamel thickness, namely the distance from the tooth surface to the dentinal-enamel junction (DEJ). The second more novel approach is to irradiate the surface with a carbon dioxide laser to create a reference layer which resists erosion. Measuring the remaining enamel thickness proved challenging since the surface roughening and subsurface demineralization that commonly occurs during the erosion process can prevent resolution of the underlying DEJ. The areas irradiated by the laser manifested lower rates of erosion compared to the non-irradiated areas and this method appears promising but it is highly dependent on the severity of the acid challenge.

  3. Optical Coherence Tomography Angiography of Miscellaneous Retinal Disease.

    Pierro, Luisa; Battaglia Parodi, Maurizio; Rabiolo, Alessandro; Introini, Ugo; Querques, Giuseppe; Bandello, Francesco

    2016-01-01

    In this chapter, we illustrate different clinical scenarios using swept-source optical coherence tomography angiography (OCTA, Triton, Topcon, Inc., Tokyo, Japan). The instrument is based on a long wavelength scanning light (1,050 nm) that can better penetrate the deeper ocular layers, such as the choroid and sclera. Our aim was to show how OCTA can be used to study the eye vascular network in a novel and innovative fashion. We have demonstrated that a specific disease can involve one or more layers; conversely, the same layer may be affected by different ocular pathologies. Moreover, we would like to stress that knowledge of disease pathophysiology is fundamental, and thus, we have focused our attention on the layer(s) most involved in each pathological condition. In some miscellaneous cases, the swept-source OCTA findings have corroborated with conventional imaging data (i.e. fundus photography, B-scan ultrasonography, fluorangiography and indocyanine green angiography), thus leading us to the proper diagnosis. PMID:27023316

  4. Process monitoring of additive manufacturing by using optical tomography

    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

  5. Determination of dental decay rates with optical coherence tomography

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

    2009-12-01

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

  6. Quality assessment for spectral domain optical coherence tomography (OCT) images

    Liu, Shuang; Paranjape, Amit S.; Elmaanaoui, Badr; Dewelle, Jordan; Rylander, H. Grady, III; Markey, Mia K.; Milner, Thomas E.

    2009-02-01

    Retinal nerve fiber layer (RNFL) thickness, a measure of glaucoma progression, can be measured in images acquired by spectral domain optical coherence tomography (OCT). The accuracy of RNFL thickness estimation, however, is affected by the quality of the OCT images. In this paper, a new parameter, signal deviation (SD), which is based on the standard deviation of the intensities in OCT images, is introduced for objective assessment of OCT image quality. Two other objective assessment parameters, signal to noise ratio (SNR) and signal strength (SS), are also calculated for each OCT image. The results of the objective assessment are compared with subjective assessment. In the subjective assessment, one OCT expert graded the image quality according to a three-level scale (good, fair, and poor). The OCT B-scan images of the retina from six subjects are evaluated by both objective and subjective assessment. From the comparison, we demonstrate that the objective assessment successfully differentiates between the acceptable quality images (good and fair images) and poor quality OCT images as graded by OCT experts. We evaluate the performance of the objective assessment under different quality assessment parameters and demonstrate that SD is the best at distinguishing between fair and good quality images. The accuracy of RNFL thickness estimation is improved significantly after poor quality OCT images are rejected by automated objective assessment using the SD, SNR, and SS.

  7. Assessment of transcutaneous vaccine delivery by optical coherence tomography

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

  8. Optical Coherence Tomography as a Tool in Reproductive Gynecology

    O.G. Panteleeva

    2015-09-01

    Full Text Available The objective of the investigation was to show the advisability of using optical coherence tomography (OCT for noninvasive diagnostics and monitoring of treatments in gynecological practice for female patients of reproductive age. Materials and Methods. OCT studies were performed during standard gynecological procedures like laparoscopy and colposcopy, as well as in course of pelvic inflammatory diseases of cervical neoplasia, with the use of an OKT1300U (BioMedTech, Russia. 330 patients of reproductive age (aged 18–45 were examined. The methods used for numeric processing of the OCT images were based on an analysis of histograms and on calculation of the first derivative of the OCT signal over depth. Results. The use of OCT with numeric processing of the images increases the sensitivity of laparoscopy diagnosis of latent chronic salpingitis from 43.5 to 96.0%. In the case of minimal endometriosis, OCT can be used as a substitute for excisional biopsy for the visualization and verification of endometrioid heterotopias. The use of OCT in the case of cervical neoplasia in female patients of reproductive age enables a considerable decrease in surgical aggression during the diagnosis and treatment of cervical intraepithelial neoplasia and early forms of cancer. Conclusion. The use of OCT helps to maximize individualization and organ preservation during the diagnosis and treatment of gynecological pathology, and therefore to preserve the reproductive potential of young female patients.

  9. Process monitoring of additive manufacturing by using optical tomography

    Zenzinger, Guenter, E-mail: guenter.zenzinger@mtu.de, E-mail: alexander.ladewig@mtu.de; Bamberg, Joachim, E-mail: guenter.zenzinger@mtu.de, E-mail: alexander.ladewig@mtu.de; Ladewig, Alexander, E-mail: guenter.zenzinger@mtu.de, E-mail: alexander.ladewig@mtu.de; Hess, Thomas, E-mail: guenter.zenzinger@mtu.de, E-mail: alexander.ladewig@mtu.de; Henkel, Benjamin, E-mail: guenter.zenzinger@mtu.de, E-mail: alexander.ladewig@mtu.de; Satzger, Wilhelm, E-mail: guenter.zenzinger@mtu.de, E-mail: alexander.ladewig@mtu.de [MTU Aero Engines AG, Dachauerstrasse 665, 80995 Munich (Germany)

    2015-03-31

    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.

  10. Comparison of optical coherence tomography imaging of cataracts with histopathology

    DiCarlo, Cheryl D.; Roach, William P.; Gagliano, Donald A.; Boppart, Stephen A.; Hammer, Daniel X.; Cox, Ann B.; Fujimoto, James G.

    1999-10-01

    This paper presents a comparison of in vivo optical coherence tomography (OCT) captured cataract images to subsequent histopathological examination of the lenticular opacities. OCT imaging was performed on anesthetized Rhesus monkeys, known as the delayed effects colony (DEC), with documented cataracts. These monkeys were exposed to several types of radiation during the mid and late 1960s. The radiation and age related cataracts in these animals were closely monitored using a unique grading system developed specifically for the DEC. In addition to this system, a modified version of a common cataract grading scheme for use in humans was applied. Of the original 18 monkeys imaged, lenses were collected at necropsy from seven of these animals, processed, and compared to OCT images. Results showed a direct correlation between the vertical OCT images and the cataractous lesions seen on corresponding histopathological sections of the lenses. Based on the images obtained and their corresponding documented comparison to histopathology, OCT showed tremendous potential to aid identification and characterization of cataracts. There can be artifactual problems with the images related to movement and shadows produced by opacities. However, with the advent of increased speed in imaging and multiplanar imaging, these disadvantages may easily be overcome.

  11. Angiographic and Optical Coherence Tomography Insights Into Bioresorbable Scaffold Thrombosis

    Karanasos, Antonios; Van Mieghem, Nicolas; van Ditzhuijzen, Nienke; Felix, Cordula; Daemen, Joost; Autar, Anouchska; Onuma, Yoshinobu; Kurata, Mie; Diletti, Roberto; Valgimigli, Marco; Kauer, Floris; van Beusekom, Heleen; de Jaegere, Peter; Zijlstra, Felix; van Geuns, Robert-Jan

    2015-01-01

    Background— As bioresorbable vascular scaffolds (BVSs) are being increasingly used in complex real-world lesions and populations, BVS thrombosis cases have been reported. We present angiographic and optical coherence tomography (OCT) findings in a series of patients treated in our center for definite bioresorbable scaffold thrombosis. Methods and Results— Up to June 2014, 14 patients presented with definite BVS thrombosis in our center. OCT was performed in 9 patients at the operator’s discretion. Angiographic and OCT findings were compared with a control group comprising 15 patients with definite metallic stent thrombosis. In the BVS group, time interval from index procedure to scaffold thrombosis ranged from 0 to 675 days. Incomplete lesion coverage by angiography was identified in 4 of 14 cases, malapposition by OCT in 5 of 9 cases, strut discontinuity in 2 of 9 cases, and underexpansion in 2 of 9 cases. Five patients had discontinued dual antiplatelet therapy, and in 3 of them discontinued dual antiplatelet therapy discontinuation had occurred the week preceding the event. There were no significant differences in angiographic or OCT findings between BVS and metallic stent thrombosis. Conclusions— Suboptimal implantation with incomplete lesion coverage, underexpansion, and malapposition comprises the main pathomechanism for both early and late BVS thrombosis, similar to metallic stent thrombosis. Dual antiplatelet therapy discontinuation seems to also be a secondary contributor in several late events. Our observations suggest that several potential triggers for BVS thrombosis could be avoided. PMID:25969547

  12. Optical coherence tomography use in the diagnosis of enamel defects

    Al-Azri, Khalifa; Melita, Lucia N.; Strange, Adam P.; Festy, Frederic; Al-Jawad, Maisoon; Cook, Richard; Parekh, Susan; Bozec, Laurent

    2016-03-01

    Molar incisor hypomineralization (MIH) affects the permanent incisors and molars, whose undermineralized matrix is evidenced by lesions ranging from white to yellow/brown opacities to crumbling enamel lesions incapable of withstanding normal occlusal forces and function. Diagnosing the condition involves clinical and radiographic examination of these teeth, with known limitations in determining the depth extent of the enamel defects in particular. Optical coherence tomography (OCT) is an emerging hard and soft tissue imaging technique, which was investigated as a new potential diagnostic method in dentistry. A comparison between the diagnostic potential of the conventional methods and OCT was conducted. Compared to conventional imaging methods, OCT gave more information on the structure of the enamel defects as well as the depth extent of the defects into the enamel structure. Different types of enamel defects were compared, each type presenting a unique identifiable pattern when imaged using OCT. Additionally, advanced methods of OCT image analysis including backscattered light intensity profile analysis and enface reconstruction were performed. Both methods confirmed the potential of OCT in enamel defects diagnosis. In conclusion, OCT imaging enabled the identification of the type of enamel defect and the determination of the extent of the enamel defects in MIH with the advantage of being a radiation free diagnostic technique.

  13. Tissue thickness calculation in ocular optical coherence tomography.

    Alonso-Caneiro, David; Read, Scott A; Vincent, Stephen J; Collins, Michael J; Wojtkowski, Maciej

    2016-02-01

    Thickness measurements derived from optical coherence tomography (OCT) images of the eye are a fundamental clinical and research metric, since they provide valuable information regarding the eye's anatomical and physiological characteristics, and can assist in the diagnosis and monitoring of numerous ocular conditions. Despite the importance of these measurements, limited attention has been given to the methods used to estimate thickness in OCT images of the eye. Most current studies employing OCT use an axial thickness metric, but there is evidence that axial thickness measures may be biased by tilt and curvature of the image. In this paper, standard axial thickness calculations are compared with a variety of alternative metrics for estimating tissue thickness. These methods were tested on a data set of wide-field chorio-retinal OCT scans (field of view (FOV) 60° x 25°) to examine their performance across a wide region of interest and to demonstrate the potential effect of curvature of the posterior segment of the eye on the thickness estimates. Similarly, the effect of image tilt was systematically examined with the same range of proposed metrics. The results demonstrate that image tilt and curvature of the posterior segment can affect axial tissue thickness calculations, while alternative metrics, which are not biased by these effects, should be considered. This study demonstrates the need to consider alternative methods to calculate tissue thickness in order to avoid measurement error due to image tilt and curvature. PMID:26977367

  14. Imaging of artificial cartilage with optical coherence tomography

    Eder, K.; Schmitt, R.; Müller-Rath, R.

    2008-02-01

    Tissue Engineering methods have become more and more relevant for orthopedic applications, especially for cartilage repair with autologous chondrocytes. In order to monitor the healing process and bonding between cartilage and the artificial implant, the boundary zone must be imaged non-invasively, for example with OCT. Optical Coherence Tomography (OCT) is a short coherent light based measuring technique which allows the generation of cross-section images of semi-transparent media with a depth resolution of up to 5 μm and a measuring depth of 1-2 mm. Especially for the imaging of cartilage OCT offers new diagnostic possibilities, as conventional methods such as ultrasound and x-ray imaging often do not yield satisfactory resolution or contrast. In this paper, an OCT measurement setup for imaging of human cartilage tissue with OCT is demonstrated, allowing a detection of local damaging and lesions. Furthermore, both compressed and uncompressed collagen gel pads were implanted into human cartilage samples. OCT measurements are presented for samples in different stages of growth, focusing on the boundary zones. Comparisons with histologies are shown, demonstrating the ability of OCT to enable a monitoring of the healing progress in tissue engineering based therapy.

  15. Diagnosis of oral submucous fibrosis with optical coherence tomography

    Lee, Cheng-Kuang; Tsai, Meng-Tsan; Lee, Hsiang-Chieh; Chen, Hsin-Ming; Chiang, Chun-Pin; Wang, Yih-Ming; Yang, C. C.

    2009-09-01

    The epithelium (EP) thickness and the standard deviation (SD) of A-mode scan intensity in the laminar propria (LP) layer are used as effective indicators for the diagnosis of oral submucous fibrosis (OSF) based on the noninvasive clinical scanning of a swept-source optical coherence tomography (OCT) system of ~6 μm in axial resolution (in tissue) and 103 dB in sensitivity. Compared with the corresponding parameters in healthy oral mucosal mucosa, in OSF mucosa, the EP thickness becomes smaller and the SD of A-mode scan intensity in the LP layer (LP SD) also becomes smaller. The LP SD can also be used for effectively differentiating OSF (small LP SD) from lesion (large LP SD). This application is particularly useful in the case of a lesion without a clear surface feature. Meanwhile, the use of the SD of A-mode scan intensity in the EP layer (EP SD) can further help in differentiating OSF (medium EP SD) from healthy oral mucosal (small EP SD) and lesion (large EP SD) conditions. Compared with the conventional method of maximum mouth opening measurement, the use of the proposed OCT scanning results can be a more effective technique for OSF diagnosis.

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

    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.

  17. Optimising deep anterior lamellar keratoplasty (DALK) using intraoperative online optical coherence tomography (iOCT)

    Steven, Philipp; Le Blanc, Carolin; Lankenau, Eva; Krug, Marc; Oelckers, Stefan; Heindl, Ludwig M.; Gehlsen, Uta; Huettmann, Gereon; Cursiefen, Claus

    2014-01-01

    Background/aims To describe the use of intraoperative online optical coherence tomography (iOCT) for improving deep anterior lamellar keratoplasty (DALK) surgery. Methods Retrospective case series of 6 eyes of 6 male patients with keratokonus, corneal dystrophy or herpetic stromal scars undergoing DALK were investigated using intraoperative optical coherence tomography and postsurgical image/video analysis. Main outcome measures were: visibility of surgical steps, especially, assessment of pl...

  18. Optical Coherence Tomography as an Auxiliary Tool for the Screening of Radiation-Related Caries

    de Oliveira Mota, Cláudia Cristina Brainer; Gueiros, Luiz Alcino; Maia, Ana Marly Araújo; Santos-Silva, Alan Roger; Gomes, Anderson Stevens Leonidas; de Abreu Alves, Fábio; Leão, Jair Carneiro; de Freitas, Anderson Zanardi; Goes, Mário; Lopes, Márcio Ajudarte

    2013-01-01

    Objective: The aim of this study was to evaluate the morphological alterations of radiation-related caries using optical coherence tomography. Methods: Thirty-six extracted teeth from 11 patients who had undergone radiotherapy were sectioned in the sagittal axis in the center of the carious lesion, and 100 μm thick sections were obtained from each specimen. One sample from each tooth was investigated by an optical coherence tomography (OCT) system, and the results were compared with histologi...

  19. Magnetic induction tomography using an all-optical ^87Rb atomic magnetometer

    Wickenbrock, Arne; Jurgilas, Sarunas; Dow, Albert; Marmugi, Luca; Renzoni, Ferruccio

    2014-11-01

    We demonstrate Magnetic Induction Tomography (MIT) with an all-optical atomic magnetometer. Our instrument creates a conductivity map of conductive objects. Both shape and size of the imaged samples compare very well with the actual shape and size. Given the potential of all-optical atomic magnetometers for miniaturization and extreme sensitivity, the proof-of-principle presented here opens up promising avenues in the development of instrumentation for magnetic induction tomography.

  20. Magnetic induction tomography using an all-optical $^{87}$Rb atomic magnetometer

    Wickenbrock, Arne; Dow, Albert; Marmugi, Luca; Renzoni, Ferruccio

    2014-01-01

    We demonstrate Magnetic Induction Tomography (MIT) with an all-optical atomic magnetometer. Our instrument creates a conductivity map of conductive objects. Both shape and size of the imaged samples compare very well with the actual shape and size. Given the potential of all-optical atomic magnetometers for miniaturization and extreme sensitivity, the proof-of-principle presented here opens up promising avenues in the development of instrumentation for magnetic induction tomography.

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

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

    2014-02-01

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

  2. An evaluation of meniscal collagenous structure using optical projection tomography

    The collagenous structure of menisci is a complex network of circumferentially oriented fascicles and interwoven radially oriented tie-fibres. To date, examination of this micro- architecture has been limited to two-dimensional imaging techniques. The purpose of this study was to evaluate the ability of the three-dimensional imaging technique; optical projection tomography (OPT), to visualize the collagenous structure of the meniscus. If successful, this technique would be the first to visualize the macroscopic orientation of collagen fascicles in 3-D in the meniscus and could further refine load bearing mechanisms in the tissue. OPT is an imaging technique capable of imaging samples on the meso-scale (1-10 mm) at a micro-scale resolution. The technique, similar to computed tomography, takes two-dimensional images of objects from incremental angles around the object and reconstructs them using a back projection algorithm to determine three-dimensional structure. Bovine meniscal samples were imaged from four locations (outer main body, femoral surface, tibial surface and inner main body) to determine the variation in collagen orientation throughout the tissue. Bovine stifles (n = 2) were obtained from a local abattoir and the menisci carefully dissected. Menisci were fixed in methanol and subsequently cut using a custom cutting jig (n = 4 samples per meniscus). Samples were then mounted in agarose, dehydrated in methanol and subsequently cleared using benzyl alcohol benzyl benzoate (BABB) and imaged using OPT. Results indicate circumferential, radial and oblique collagenous orientations at the contact surfaces and in the inner third of the main body of the meniscus. Imaging identified fascicles ranging from 80-420 μm in diameter. Transition zones where fascicles were found to have a woven or braided appearance were also identified. The outer-third of the main body was composed of fascicles oriented predominantly in the circumferential direction. Blood vessels were also visualized using this technique, as their elastin content fluoresces more brightly than collagen at the 425 nm wavelength used by the OPT scanner. OPT was capable of imaging the collagenous structure, as well as blood vessels in the bovine meniscus. Collagenous structure variability, including transition zones between structural regions not previously described in the meniscus, was identified using this novel technique

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

    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

  4. Automatic segmentation of the optic nerve head for deformation measurements in video rate optical coherence tomography

    Hidalgo-Aguirre, Maribel; Gitelman, Julian; Lesk, Mark Richard; Costantino, Santiago

    2015-11-01

    Optical coherence tomography (OCT) imaging has become a standard diagnostic tool in ophthalmology, providing essential information associated with various eye diseases. In order to investigate the dynamics of the ocular fundus, we present a simple and accurate automated algorithm to segment the inner limiting membrane in video-rate optic nerve head spectral domain (SD) OCT images. The method is based on morphological operations including a two-step contrast enhancement technique, proving to be very robust when dealing with low signal-to-noise ratio images and pathological eyes. An analysis algorithm was also developed to measure neuroretinal tissue deformation from the segmented retinal profiles. The performance of the algorithm is demonstrated, and deformation results are presented for healthy and glaucomatous eyes.

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

    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.

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

    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

  7. Electrophysiological and Anatomical Correlates of Spinal Cord Optical Coherence Tomography

    Valente, Maurizio; Krstajic, Nikola; Biella, Gabriele E. M.

    2016-01-01

    Despite the continuous improvement in medical imaging technology, visualizing the spinal cord poses severe problems due to structural or incidental causes, such as small access space and motion artifacts. In addition, positional guidance on the spinal cord is not commonly available during surgery, with the exception of neuronavigation techniques based on static pre-surgical data and of radiation-based methods, such as fluoroscopy. A fast, bedside, intraoperative real-time imaging, particularly necessary during the positioning of endoscopic probes or tools, is an unsolved issue. The objective of our work, performed on experimental rats, is to demonstrate potential intraoperative spinal cord imaging and probe guidance by optical coherence tomography (OCT). Concurrently, we aimed to demonstrate that the electromagnetic OCT irradiation exerted no particular effect at the neuronal and synaptic levels. OCT is a user-friendly, low-cost and endoscopy-compatible photonics-based imaging technique. In particular, by using a Fourier-domain OCT imager, operating at 850 nm wavelength and scanning transversally with respect to the spinal cord, we have been able to: 1) accurately image tissue structures in an animal model (muscle, spine bone, cerebro-spinal fluid, dura mater and spinal cord), and 2) identify the position of a recording microelectrode approaching and inserting into the cord tissue 3) check that the infrared radiation has no actual effect on the electrophysiological activity of spinal neurons. The technique, potentially extendable to full three-dimensional image reconstruction, shows prospective further application not only in endoscopic intraoperative analyses and for probe insertion guidance, but also in emergency and adverse situations (e.g. after trauma) for damage recognition, diagnosis and fast image-guided intervention. PMID:27050096

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

    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.

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

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

    2011-02-21

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

  10. Mechanical tissue optical clearing devices: evaluation of enhanced light penetration in skin using optical coherence tomography.

    Drew, Christopher; Milner, Thomas E; Rylander, Christopher G

    2009-01-01

    We report results of a study to evaluate effectiveness of a mechanical tissue optical clearing device (TOCD) using optical coherence tomography (OCT). The TOCD uses a pin array and vacuum pressure source to compress localized regions of the skin surface. OCT images (850 and 1310 nm) of in vivo human skin indicate application of the TOCD provides an up to threefold increased light penetration depth at spatial positions correlated with pin indentations. Increased contrast of the epidermal-dermal junction in OCT images spatially correlates with indented zones. OCT M-scans recorded while applying the TOCD indicate optical penetration depth monotonically increased, with most improvement at early times (5 to 10 s) of TOCD vacuum application. OCT M-scans of ex vivo porcine skin compressed using the TOCD suggest average group refractive index of the tissue increased, corresponding to a decrease in water concentration. Results of our study indicate that mechanical optical clearing of skin may provide an effective and efficient means to deliver increased light fluence to dermal and subdermal regions. PMID:20059257

  11. Imaging modal content of cone photoreceptors using adaptive optics optical coherence tomography

    Liu, Zhuolin; Kocaoglu, Omer P.; Turner, Timothy L.; Miller, Donald T.

    2015-03-01

    It has been long established that photoreceptors capture light based on the principles of optical waveguiding. Yet after decades of experimental and theoretical investigations considerable uncertainty remains, even for the most basic prediction as to whether photoreceptors support more than a single waveguide mode. To test for modal behavior in human cone photoreceptors, we took advantage of adaptive-optics optical coherence tomography (AO-OCT, ?c=785 nm) to noninvasively image in three dimensions the reflectance profiles generated in the inner and outer segments (IS, OS) of cones. Mode content was examined over a range of cone diameters by imaging cones from 0.6 to 10 retinal eccentricity (n = 1802). Fundamental to the method was extraction of reflections at the cone IS/OS junction and cone outer segment tip (COST). Modal content properties of size, circularity and orientation were quantified using second moment analysis. Analysis of the cone reflections indicates waveguide properties of cone IS and OS depend on segment diameter. Cone IS was found to support a single mode near the fovea (<=3) and multiple modes further away (<4). In contrast, no evidence of multiple modes was found in the cone OSs. The IS/OS and COST reflections share a common optical aperture, are most circular near the fovea, and show no orientation preference.

  12. Development and Application of Multifunctional Optical Coherence Tomography

    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, for multi-parametric study of tissue microstructure, blood vessel morphology, blood flow and lymphatic vessel all together. The thesis mainly focus on two parts: first, development of multi-functional OCT/optical microangiography (OMAG) system and methods for volumetric imaging of microvasculature and quantitative measurement of blood flow, and its application for pathological research in ophthalmology on rodent eye models; second, development of ultra-high resolution OCT system and algorithm for simultaneous label free imaging of blood and lymphatic vessel, and its application in wound healing study on mouse ear flap model. Objectives of my research are achieved through the following specific aims: Aim 1: Improve the sensitivity of OMAG for microvasculature imaging; perform volumetric and quantitative imaging of vasculature with combined OMAG and Phase-resolved Doppler OCT for in vivo study of vascular physiology. Aim 2: Develop high speed high resolution OCT system and method for rodent eye imaging. Apply the combined OMAG and Phase-resolved Doppler OCT approach to investigate the impact of elevated intraocular pressure on retinal, choroidal and optic nerve head blood flow in rat eye model, which aids to the better understanding of the mechanism and development of glaucoma. Aim 3: Apply the developed OCT system and ultra-high sensitive OMAG algorithm for noninvasive imaging of retinal morphology and microvasculature in obese mice, which may play an important role in early diagnosis of Diabetic retinopathy. Aim 4: Developing an ultra-high resolution SDOCT system using broadband Supercontinuum light source to achieve ultra-high resolution microvasculature imaging of biological tissue. Aim 5: Develop methods for simultaneous label free optical imaging of blood and lymphatic vessel and demonstrate its capability by monitoring the blood and lymph response to wound healing on mouse ear pinna model.

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

    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

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

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

  15. Study of an ultrahigh-numerical-aperture fiber continuum generation source for optical coherence tomography

    Marks, Daniel L.; Oldenburg, Amy L.; Reynolds, J. Joshua; Boppart, Stephen A.

    2002-11-01

    The axial resolution of optical coherence tomography images is primarily dependent on the bandwidth of the illumination source. Continuum generation is one way to generate the single-mode, high-bandwidth light needed for point illumination. We present an inexpensive and easy-to-implement augmentation to a Ti:sapphire laser that widens the bandwidth from 20 to over 200 nm with commerically available ultrahigh-numerical-aperture fiber. This technique can provide a readily available broad-bandwidth source for researchers and a practical enhancement to a fiber-optic optical coherence tomography system.

  16. Three-dimensional representation of late-arriving photons for detecting inhomogeneities in diffuse optical tomography

    A method for rapid detection of absorbing inhomogeneity in a strongly scattering medium having the properties of a biological tissue before the image reconstruction is described based on the principles of diffuse optical tomography. The method is based on preliminary processing of a three-dimensional surface obtained from the set of time-resolved data in the Cartesian coordinate system, followed by its conformal transformation into two surfaces in the cylindrical coordinate system. A specific feature of the method is the use of late-arriving photons, scattered and diffusely transmitted through an optically turbid object. (optical tomography)

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

    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

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

    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.

  19. Automated 3D segmentation of intraretinal layers from optic nerve head optical coherence tomography images

    Antony, Bhavna J.; Abrmoff, Michael D.; Lee, Kyungmoo; Sonkova, Pavlina; Gupta, Priya; Kwon, Young; Niemeijer, Meindert; Hu, Zhihong; Garvin, Mona K.

    2010-03-01

    Optical coherence tomography (OCT), being a noninvasive imaging modality, has begun to find vast use in the diagnosis and management of ocular diseases such as glaucoma, where the retinal nerve fiber layer (RNFL) has been known to thin. Furthermore, the recent availability of the considerably larger volumetric data with spectral-domain OCT has increased the need for new processing techniques. In this paper, we present an automated 3-D graph-theoretic approach for the segmentation of 7 surfaces (6 layers) of the retina from 3-D spectral-domain OCT images centered on the optic nerve head (ONH). The multiple surfaces are detected simultaneously through the computation of a minimum-cost closed set in a vertex-weighted graph constructed using edge/regional information, and subject to a priori determined varying surface interaction and smoothness constraints. The method also addresses the challenges posed by presence of the large blood vessels and the optic disc. The algorithm was compared to the average manual tracings of two observers on a total of 15 volumetric scans, and the border positioning error was found to be 7.25 +/- 1.08 ?m and 8.94 +/- 3.76 ?m for the normal and glaucomatous eyes, respectively. The RNFL thickness was also computed for 26 normal and 70 glaucomatous scans where the glaucomatous eyes showed a significant thinning (p < 0.01, mean thickness 73.7 +/- 32.7 ?m in normal eyes versus 60.4 +/- 25.2 ?m in glaucomatous eyes).

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

    Cânjǎu, Silvana; Todea, Carmen; Sinescu, Cosmin; Negrutiu, Meda L.; Duma, Virgil; Mǎnescu, Adrian; Topalǎ, Florin I.; Podoleanu, Adrian Gh.

    2013-06-01

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

  1. 3D Human cartilage surface characterization by optical coherence tomography

    Brill, Nicolai; Riedel, Jörn; Schmitt, Robert; Tingart, Markus; Truhn, Daniel; Pufe, Thomas; Jahr, Holger; Nebelung, Sven

    2015-10-01

    Early diagnosis and treatment of cartilage degeneration is of high clinical interest. Loss of surface integrity is considered one of the earliest and most reliable signs of degeneration, but cannot currently be evaluated objectively. Optical Coherence Tomography (OCT) is an arthroscopically available light-based non-destructive real-time imaging technology that allows imaging at micrometre resolutions to millimetre depths. As OCT-based surface evaluation standards remain to be defined, the present study investigated the diagnostic potential of 3D surface profile parameters in the comprehensive evaluation of cartilage degeneration. To this end, 45 cartilage samples of different degenerative grades were obtained from total knee replacements (2 males, 10 females; mean age 63.8 years), cut to standard size and imaged using a spectral-domain OCT device (Thorlabs, Germany). 3D OCT datasets of 8  ×  8, 4  ×  4 and 1  ×  1 mm (width  ×  length) were obtained and pre-processed (image adjustments, morphological filtering). Subsequent automated surface identification algorithms were used to obtain the 3D primary profiles, which were then filtered and processed using established algorithms employing ISO standards. The 3D surface profile thus obtained was used to calculate a set of 21 3D surface profile parameters, i.e. height (e.g. Sa), functional (e.g. Sk), hybrid (e.g. Sdq) and segmentation-related parameters (e.g. Spd). Samples underwent reference histological assessment according to the Degenerative Joint Disease classification. Statistical analyses included calculation of Spearman’s rho and assessment of inter-group differences using the Kruskal Wallis test. Overall, the majority of 3D surface profile parameters revealed significant degeneration-dependent differences and correlations with the exception of severe end-stage degeneration and were of distinct diagnostic value in the assessment of surface integrity. None of the 3D surface profile parameters investigated were capable of reliably differentiating healthy from early-degenerative cartilage, while scan area sizes considerably affected parameter values. In conclusion, cartilage surface integrity may be adequately assessed by 3D surface profile parameters, which should be used in combination for the comprehensive and thorough evaluation and overall improved diagnostic performance. OCT- and image-based surface assessment could become a valuable adjunct tool to standard arthroscopy.

  2. Assessment of Sentinel Node Biopsies With Full-Field Optical Coherence Tomography.

    Grieve, Kate; Mouslim, Karima; Assayag, Osnath; Dalimier, Eugénie; Harms, Fabrice; Bruhat, Alexis; Boccara, Claude; Antoine, Martine

    2016-04-01

    Current techniques for the intraoperative analysis of sentinel lymph nodes during breast cancer surgery present drawbacks such as time and tissue consumption. Full-field optical coherence tomography is a novel noninvasive, high-resolution, fast imaging technique. This study investigated the use of full-field optical coherence tomography as an alternative technique for the intraoperative analysis of sentinel lymph nodes. Seventy-one axillary lymph nodes from 38 patients at Tenon Hospital were imaged minutes after excision with full-field optical coherence tomography in the pathology laboratory, before being handled for histological analysis. A pathologist performed a blind diagnosis (benign/malignant), based on the full-field optical coherence tomography images alone, which resulted in a sensitivity of 92% and a specificity of 83% (n = 65 samples). Regular feedback was given during the blind diagnosis, with thorough analysis of the images, such that features of normal and suspect nodes were identified in the images and compared with histology. A nonmedically trained imaging expert also performed a blind diagnosis aided by the reading criteria defined by the pathologist, which resulted in 85% sensitivity and 90% specificity (n = 71 samples). The number of false positives of the pathologist was reduced by 3 in a second blind reading a few months later. These results indicate that following adequate training, full-field optical coherence tomography can be an effective noninvasive diagnostic tool for extemporaneous sentinel node biopsy qualification. PMID:25804544

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

    2013-01-01

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

  4. Time-Gated Optical Projection Tomography Allows Visualization of Adult Zebrafish Internal Structures

    L. Fieramonti; Bassi, A; FOGLIA, E.; A. Pistocchi; C. D'Andrea; Valentini, G; R. Cubeddu; De Silvestri, S.; Cerullo, G.; F. Cotelli

    2012-01-01

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

  5. Born Normalization for Fluorescence Optical Projection Tomography for Whole Heart Imaging

    Razansky, Daniel; Figueiredo, Jose-Luiz; Fexon, Lyuba; Ntziachristos, Vasilis; Vinegoni, Claudio; Pivovarov, Misha; Nahrendorf, Matthias; Weissleder, Ralph

    2009-01-01

    Optical projection tomography is a three-dimensional imaging technique that has been recently introduced as an imaging tool primarily in developmental biology and gene expression studies. The technique renders biological sample optically transparent by first dehydrating them and then placing in a mixture of benzyl alcohol and benzyl benzoate in a 2:1 ratio (BABB or Murray s Clear solution). The technique renders biological samples optically transparent by first dehydrating them in graded etha...

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

    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.

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

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

  8. Effect of optical clearing agents on optical coherence tomography images of cervical epithelium.

    Gallwas, Julia; Stanchi, Anna; Ditsch, Nina; Schwarz, Theresa; Dannecker, Christian; Mueller, Susanna; Stepp, Herbert; Mortensen, Uwe

    2015-02-01

    Optical coherence tomography (OCT) can be used as an adjunct to colposcopy in order to detect precancerous and cancerous cervical lesions. Optical clearing agents (OCAs) temporarily reduce the optical scattering of biological tissues. The purpose of this study was to investigate their influence on OCT imaging. OCT images were taken from unsuspicious and suspicious areas of fresh conization specimens immediately after resection and 5, 10, and 20 min after application of dimethyl sulfoxide (DMSO) or polyethylene glycol (PEG). Corresponding histologies were obtained from all sites. The images taken 5, 10, and 20 min after application of OCA were compared to the initial images with respect to changes in brightness, contrast, and scanning depth using a standard nonparametric test of differences of proportions. Further, mean intensity backscattering curves were calculated from all OCT images in the histological groups CIN2, CIN3, inflammation, and normal epithelium. Mean difference profiles within each of these groups were determined, reflecting the mean differences between the condition before the application of OCA and the exposure times 5, 10, and 20 min, respectively. The null hypothesis was tested employing the Dicky-Fuller-test, Hotelings-test and run test. The visual analysis of 434 OCT images from 109 different sites of 24 conization specimens showed a statistically significant increase in brightness and contrast for normal and dysplastic epithelium after application of DMSO or PEG. Further, the analysis of mean intensity profiles suggests the existence of an increased backscattering intensity after application of DMSO or PEG. DMSO and PEG contribute substantially to optical clearing in cervical squamous epithelium and therefore influence OCT imaging in a positive way. With further refinement of the OCT technology, the observed changes may be beneficial in interpreting the tissue microstructure and identifying cervical intraepithelial neoplasia. PMID:25503301

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

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

    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...... 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...... 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....

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

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

  11. Current and future potential of retinal optical coherence tomography in multiple sclerosis with and without optic neuritis.

    Balk, Lisanne J; Petzold, Axel

    2014-01-01

    Multiple sclerosis (MS) is a disorder characterized by inflammation and neuroaxonal degeneration. The latter is held responsible for the irreversible disability in patients with MS. The eye is a unique window into the brain. With the advent of optical coherence tomography, accurate quantification of retinal layer thickness has become feasible. Neuroaxonal degeneration affecting the retinal layers is structurally and functionally related to pathology in the visual pathways, which is most severe following MS optic neuritis. This is relevant to recognize because MS optic neuritis may mask the subtle thinning of retinal layers associated with global CNS atrophy, which is also related to more global loss of neurological function. Taken together, optical coherence tomography stands at the brink of becoming a validated imaging biomarker for monitoring neurodegeneration in MS and to provide end points for clinical trials. PMID:24832034

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

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

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

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

    Dhalla, Al-Hafeez; Shia, Kevin; Izatt, Joseph A

    2012-12-01

    We describe a novel buffering technique for increasing the A-scan rate of swept source optical coherence tomography (SSOCT) systems employing low duty cycle swept source lasers. This technique differs from previously reported buffering techniques in that it employs a fast optical switch, capable of switching in 60 ns, instead of a fused fiber coupler at the end of the buffering stage, and is therefore appreciably more power efficient. The use of the switch also eliminates patient exposure to light that is not used for imaging that occurs at the end of the laser sweep, thereby increasing the system sensitivity. We also describe how careful management of polarization can remove undesirable artifacts due to polarization mode dispersion. In addition, we demonstrate how numerical compensation techniques can be used to modify the signal from a Mach-Zehnder interferometer (MZI) clock obtained from the original sweep to recalibrate the buffered sweep, thereby reducing the complexity of systems employing lasers with integrated MZI clocks. Combining these methods, we constructed an SSOCT system employing an Axsun technologies laser with a sweep rate of 100kHz and 6dB imaging range of 5.5mm. The sweep rate was doubled with sweep buffering to 200 kHz, and the imaging depth was extended to 9 mm using coherence revival. We demonstrated the feasibility of this system by acquiring images of the anterior segments and retinas of healthy human volunteers. PMID:23243559

  15. Integrated optical coherence tomography and optical coherence microscopy imaging of human pathology

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

    2010-02-01

    Excisional biopsy is the current gold standard for disease diagnosis; however, it requires a relatively long processing time and it may also suffer from unacceptable false negative rates due to sampling errors. Optical coherence tomography (OCT) is a promising imaging technique that provide real-time, high resolution and three-dimensional (3D) images of tissue morphology. Optical coherence microscopy (OCM) is an extension of OCT, combining both the coherence gating and the confocal gating techniques. OCM imaging achieves cellular resolution with deeper imaging depth compared to confocal microscopy. An integrated OCT/OCM imaging system can provide co-registered multiscale imaging of tissue morphology. 3D-OCT provides architectural information with a large field of view and can be used to find regions of interest; while OCM provides high magnification to enable cellular imaging. The integrated OCT/OCM system has an axial resolution of kidney (19), were imaged with OCT and OCM within 2 to 6 hours after excision. The images were compared with H & E histology to identify characteristic features useful for disease diagnosis. The feasibility of visualizing human pathology using integrated OCT/OCM was demonstrated in the pathology laboratory settings.

  16. Achromatic registration of quadrature components of the optical spectrum in spectral domain optical coherence tomography

    We have thoroughly investigated the method of simultaneous reception of spectral components with the achromatised quadrature phase shift between two portions of a reference wave, designed for the effective suppression of the 'mirror' artefact in the resulting image obtained by means of spectral domain optical coherence tomography (SD OCT). We have developed and experimentally tested a phase-shifting element consisting of a beam divider, which splits the reference optical beam into the two beams, and of delay lines being individual for each beam, which create a mutual phase difference of π/2 in the double pass of the reference beam. The phase shift achromatism over a wide spectral range is achieved by using in the delay lines the individual elements with different dispersion characteristics. The ranges of admissible adjustment parameters of the achromatised delay line are estimated for exact and inexact conformity of the geometric characteristics of its components to those calculated. A possibility of simultaneous recording of the close-to-quadrature spectral components with a single linear photodetector element is experimentally confirmed. The suppression of the artefact mirror peak in the OCT-signal by an additional 9 dB relative to the level of its suppression is experimentally achieved when the air delay line is used. Two-dimensional images of the surface positioned at an angle to the axis of the probe beam are obtained with the correction of the 'mirror' artefact while maintaining the dynamic range of the image. (laser biophotonics)

  17. Optical Coherence Tomography for the Evaluation of Retinal and Optic Nerve Morphology in Animal Subjects: Practical Considerations

    McLellan, Gillian J; Rasmussen, Carol A

    2012-01-01

    Optical coherence tomography (OCT) is a non-invasive, non-contact imaging technique capable of producing high-resolution images of the retina and optic nerve. These images provide information that is useful for following the progression and/or resolution of posterior segment disease. Rapid advances in OCT technology allow the acquisition of increasingly detailed images, approaching the original goal of providing in vivo histopathology. Increases in scan acquisition speeds and axial resolution...

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

    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.

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

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

    2013-01-01

    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......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...

  20. Fingerprint imaging from the inside of a finger with full-field optical coherence tomography.

    Auksorius, Egidijus; Boccara, A Claude

    2015-11-01

    Imaging below fingertip surface might be a useful alternative to the traditional fingerprint sensing since the internal finger features are more reliable than the external ones. One of the most promising subsurface imaging technique is optical coherence tomography (OCT), which, however, has to acquire 3-D data even when a single en face image is required. This makes OCT inherently slow for en face imaging and produce unnecessary large data sets. Here we demonstrate that full-field optical coherence tomography (FF-OCT) can be used to produce en face images of sweat pores and internal fingerprints, which can be used for the identification purposes. PMID:26601009

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

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

  2. Optical coherence tomography in papilledema and pseudopapilledema with and without optic nerve head drusen

    Shikha Talwar Bassi

    2014-01-01

    Full Text Available Aim: To compare the spectral domain optical coherence tomography (SD-OCT findings of the optic disc and the peripapillary retina of patients with a true papilledema and pseudopapilledema with and without optic nerve head drusen (ONHD. Study Design: Retrospective Case Control Study. Subjects and Methods: Peripapillary retinal nerve fiber layer (PPRNFL thickness as depicted by SD-OCT of 94 eyes of 66 patients with papilledema (30 eyes, pseudopapiledema (31 eyes, and normal controls (33 eyes was analyzed. The mean RNFL thickness, total retinal thickness (TRT at a superior and inferior edge of the disc and the quadrant wise topography of increased RNFL were compared in all three groups. Sensitivity, specificity, and area under the receiver operating characteristic curve (AROC were calculated for all the parameters. Results: The median RNFL thickness was 185.4 (129.5-349.3 μm, 122.3 (109-156.3 μm and 91.62 ± 7 μm in papilledema, pseudopapilledema, and controls, respectively. Papilledema group had thicker PPRNFL in all quadrants except temporal quadrant. TRT was thicker in papilledema and pseudopapilledema compared to controls. ONHD could be directly visualized as high reflective clumps in the sub-retinal space or the RNFL in 30 eyes. Increased RNFL thickness in all four quadrants was noted 43.3% in papilledema and 9.7% in pseudopapilledema. Normal RNFL thickness in all four quadrants was noted in 0% in papilledema and 32.3% in pseudopapilledema. Nasal RNFL had the highest AROC (0.792 indicating high diagnostic ability to differentiate papilledema from pseudopapilledema. Conclusion: SD-OCT can be used as a tool to differentiate between papilledema and pseudopapilledema.

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

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

    2011-01-01

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

  4. Multi-parametric imaging of murine brain using spectral and time domain optical coherence tomography

    Bukowska, Danuta; Ruminski, Daniel; Szlag, Daniel; Grulkowski, Ireneusz; Wlodarczyk, Jakub; Szkulmowski, Maciej; Wilczynski, Grzegorz; Gorczynska, Iwona; Wojtkowski, Maciej

    2012-10-01

    Examination of brain functions in small animal models may help improve the diagnosis and treatment of neurological conditions. Transcranial imaging of small rodents' brains poses a major challenge for optical microscopy. Another challenge is to reduce the measurement time. We describe methods and algorithms for three-dimensional assessment of blood flow in the brains of small animals, through the intact skull, using spectral and time domain optical coherence tomography. By introducing a resonant scanner to the optical setup of the optical coherence tomography (OCT) system, we have developed and applied a high-speed spectral OCT technique that allows us to vary the imaging range of flow and to shorten measurement time. Multi-parameter signal analysis enables us to obtain both qualitative and quantitative information about flow velocity from the same set of data.

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

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

    2012-01-01

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

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

    Purpose: The cone beam computed tomography (CBCT) guided small animal radiation research platform (SARRP) has been developed for focal tumor irradiation, allowing laboratory researchers to test basic biological hypotheses that can modify radiotherapy outcomes in ways that were not feasible previously. CBCT provides excellent bone to soft tissue contrast, but is incapable of differentiating tumors from surrounding soft tissue. Bioluminescence tomography (BLT), in contrast, allows direct visualization of even subpalpable tumors and quantitative evaluation of tumor response. Integration of BLT with CBCT offers complementary image information, with CBCT delineating anatomic structures and BLT differentiating luminescent tumors. This study is to develop a systematic method to calibrate an integrated CBCT and BLT imaging system which can be adopted onboard the SARRP to guide focal tumor irradiation. Methods: The integrated imaging system consists of CBCT, diffuse optical tomography (DOT), and BLT. The anatomy acquired from CBCT and optical properties acquired from DOT serve as a priori information for the subsequent BLT reconstruction. Phantoms were designed and procedures were developed to calibrate the CBCT, DOT/BLT, and the entire integrated system. Geometrical calibration was performed to calibrate the CBCT system. Flat field correction was performed to correct the nonuniform response of the optical imaging system. Absolute emittance calibration was performed to convert the camera readout to the emittance at the phantom or animal surface, which enabled the direct reconstruction of the bioluminescence source strength. Phantom and mouse imaging were performed to validate the calibration. Results: All calibration procedures were successfully performed. Both CBCT of a thin wire and a euthanized mouse revealed no spatial artifact, validating the accuracy of the CBCT calibration. The absolute emittance calibration was validated with a 650 nm laser source, resulting in a 3.0% difference between simulated and measured signal. The calibration of the entire system was confirmed through the CBCT and BLT reconstruction of a bioluminescence source placed inside a tissue-simulating optical phantom. Using a spatial region constraint, the source position was reconstructed with less than 1 mm error and the source strength reconstructed with less than 24% error. Conclusions: A practical and systematic method has been developed to calibrate an integrated x-ray and optical tomography imaging system, including the respective CBCT and optical tomography system calibration and the geometrical calibration of the entire system. The method can be modified and adopted to calibrate CBCT and optical tomography systems that are operated independently or hybrid x-ray and optical tomography imaging systems

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

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

    2015-04-15

    Purpose: The cone beam computed tomography (CBCT) guided small animal radiation research platform (SARRP) has been developed for focal tumor irradiation, allowing laboratory researchers to test basic biological hypotheses that can modify radiotherapy outcomes in ways that were not feasible previously. CBCT provides excellent bone to soft tissue contrast, but is incapable of differentiating tumors from surrounding soft tissue. Bioluminescence tomography (BLT), in contrast, allows direct visualization of even subpalpable tumors and quantitative evaluation of tumor response. Integration of BLT with CBCT offers complementary image information, with CBCT delineating anatomic structures and BLT differentiating luminescent tumors. This study is to develop a systematic method to calibrate an integrated CBCT and BLT imaging system which can be adopted onboard the SARRP to guide focal tumor irradiation. Methods: The integrated imaging system consists of CBCT, diffuse optical tomography (DOT), and BLT. The anatomy acquired from CBCT and optical properties acquired from DOT serve as a priori information for the subsequent BLT reconstruction. Phantoms were designed and procedures were developed to calibrate the CBCT, DOT/BLT, and the entire integrated system. Geometrical calibration was performed to calibrate the CBCT system. Flat field correction was performed to correct the nonuniform response of the optical imaging system. Absolute emittance calibration was performed to convert the camera readout to the emittance at the phantom or animal surface, which enabled the direct reconstruction of the bioluminescence source strength. Phantom and mouse imaging were performed to validate the calibration. Results: All calibration procedures were successfully performed. Both CBCT of a thin wire and a euthanized mouse revealed no spatial artifact, validating the accuracy of the CBCT calibration. The absolute emittance calibration was validated with a 650 nm laser source, resulting in a 3.0% difference between simulated and measured signal. The calibration of the entire system was confirmed through the CBCT and BLT reconstruction of a bioluminescence source placed inside a tissue-simulating optical phantom. Using a spatial region constraint, the source position was reconstructed with less than 1 mm error and the source strength reconstructed with less than 24% error. Conclusions: A practical and systematic method has been developed to calibrate an integrated x-ray and optical tomography imaging system, including the respective CBCT and optical tomography system calibration and the geometrical calibration of the entire system. The method can be modified and adopted to calibrate CBCT and optical tomography systems that are operated independently or hybrid x-ray and optical tomography imaging systems.

  8. Tomography

    Already widely accepted in medicine, tomography can also be useful in industry. The theory behind tomography and a demonstration of the technique to inspect a motorcycle carburetor is presented. To demonstrate the potential of computer assisted tomography (CAT) to accurately locate defects in three dimensions, a sectioned 5 cm gate valve with a shrink cavity made visible by the sectioning was tomographically imaged using a Co-60 source. The tomographic images revealed a larger cavity below the sectioned surface. The position of this cavity was located with an in-plane and axial precision of approximately +-1 mm. The volume of the cavity was estimated to be approximately 40 mm3

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

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

    2008-02-08

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

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

    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.

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

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

    2006-01-01

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

  12. Ultrahigh-speed ultrahigh-resolution adaptive optics: optical coherence tomography system for in-vivo small animal retinal imaging

    Jian, Yifan; Xu, Jing; Zawadzki, Robert J.; Sarunic, Marinko V.

    2013-03-01

    Small animal models of human retinal diseases are a critical component of vision research. In this report, we present an ultrahigh-resolution ultrahigh-speed adaptive optics optical coherence tomography (AO-OCT) system for small animal retinal imaging (mouse, fish, etc.). We adapted our imaging system to different types of small animals in accordance with the optical properties of their eyes. Results of AO-OCT images of small animal retinas acquired with AO correction are presented. Cellular structures including nerve fiber bundles, capillary networks and detailed double-cone photoreceptors are visualized.

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

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

    2015-08-01

    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-μm 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.

  14. Pump-probe quantum state tomography in a semiconductor optical amplifier.

    Grosse, N B; Owschimikow, N; Aust, R; Lingnau, B; Koltchanov, A; Kolarczik, M; Lüdge, K; Woggon, U

    2014-12-29

    Pump-probe quantum state tomography was applied to the transmission of a coherent state through an In(Ga)As based quantum dot optical amplifier during the interaction with an optical pump pulse. The Wigner function and the statistical moments of the field were extracted and used to determine the degree of population inversion and the signal-to-noise ratio in a sub-picosecond time window. PMID:25607214

  15. Characterization of Flow Dynamics in Vessels with Complex Geometry using Doppler Optical Coherence Tomography

    Bonesi, Marco

    2008-01-01

    The study of flow dynamics in complex geometry vessels is highly important in many biomedical applications where the knowledge of the mechanic interactions between the moving fluid and the housing media plays a key role for the determination of the parameters of interest, including the effect of blood flow on the possible rupture of atherosclerotic plaques. Doppler Optical Coherence Tomography (DOCT) is an optic, non-contact, non-invasive technique able to achieve detailed anal...

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

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

    2014-01-01

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

  17. Two-dimensional optical tomography of hemodynamic changes in a preterm infant brain

    Gao, Feng; Xue, Yuan; Zhao, Huijuan; Kusaka, Takashi; Ueno, Masanori; Yamada, Yukio

    2007-08-01

    Our preliminary results on two-dimensional (2D) optical tomographic imaging of hemodynamic changes in a preterm infant brain are reported. We use the established 16-channel time-correlated single photon counting system for the detection and generalized pulse spectrum technique based algorithm for the image reconstruction. The experiments demonstrate that diffuse optical tomography may be a potent means for investigating brain functions and neural development of infant brains in the perinatal period.

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

    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...

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

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

  20. Integrated system for combined Raman spectroscopy–spectral domain optical coherence tomography

    Patil, C. A.; Kalkman, J; Faber, D. J.; Nyman, J.S.; Leeuwen; Mahadevan-Jansen, A

    2011-01-01

    Raman spectroscopy (RS) and optical coherence tomography (OCT) are powerful tools for optical analysis of tissues with mutually complementary strengths and limitations. OCT excels at visualizing tissue microstructure but lacks molecular specificity, while RS can relay tissue biochemical composition but typically cannot relate microstructure. Previous implementations of combined RS-OCT have utilized a common sample arm while maintaining independent RS and OCT detection arms. We present the des...

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

    Kushnir O.; Nek P.; 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...

  2. Magnetic induction tomography using an all-optical ??Rb atomic magnetometer.

    Wickenbrock, Arne; Jurgilas, Sarunas; Dow, Albert; Marmugi, Luca; Renzoni, Ferruccio

    2014-11-15

    We demonstrate magnetic induction tomography (MIT) with an all-optical atomic magnetometer. Our instrument creates a conductivity map of conductive objects. Both the shape and size of the imaged samples compare very well with the actual shape and size. Given the potential of all-optical atomic magnetometers for miniaturization and extreme sensitivity, the proof-of-principle presented in this Letter opens up promising avenues in the development of instrumentation for MIT. PMID:25490470

  3. Non-Invasive Detection of Early Retinal Neuronal Degeneration by Ultrahigh Resolution Optical Coherence Tomography

    Tudor, Debbie; Kajić, Vedran; Rey, Sara; Erchova, Irina; Považay, Boris; Hofer, Bernd; Powell, Kate A.; Marshall, David; Rosin, Paul L.; Drexler, Wolfgang; Morgan, James E

    2014-01-01

    Optical coherence tomography (OCT) has revolutionises the diagnosis of retinal disease based on the detection of microscopic rather than subcellular changes in retinal anatomy. However, currently the technique is limited to the detection of microscopic rather than subcellular changes in retinal anatomy. However, coherence based imaging is extremely sensitive to both changes in optical contrast and cellular events at the micrometer scale, and can generate subtle changes in the spectral content...

  4. Coherent noise-free ophthalmic imaging by spectral optical coherence tomography

    In this contribution we examine a methodology to avoid parasitic cross-correlation terms in spectral optical coherence tomography (SOCT) images. The optimal conditions of optical power and exposure time are found theoretically and confirmed experimentally to ensure that parasitic images are hidden under the shot noise. An upper limit on useful exposures may then be estimated. In a case of SOCT imaging of the retina this limit is below the ANSI safety limit

  5. A comparison of methods using optical coherence tomography to detect demineralized regions in teeth

    Sowa, Michael G; Popescu, Dan P.; Friesen, Jeri R.; Mark D. Hewko; Choo-Smith, Lin-P’ing

    2011-01-01

    Optical coherence tomography (OCT) is a three- dimensional optical imaging technique that can be used to identify areas of early caries formation in dental enamel. The OCT signal at 850 nm back-reflected from sound enamel is attenuated stronger than the signal back-reflected from demineralized regions. To quantify this observation, the OCT signal as a function of depth into the enamel (also known as the A-scan intensity), the histogram of the A-scan intensities and three sum...

  6. Correlation between polarization sensitive optical coherence tomography and second harmonic generation microscopy in skin

    Le, Viet-Hoan; lee, Seunghun; Kim, Bumju; Yoon, Yeoreum; Yoon, Calvin J.; Chung, Wan Kyun; Kim, Ki Hean

    2015-01-01

    Both polarization sensitive optical coherence tomography (PS-OCT) and second harmonic generation (SHG) microscopy are 3D optical imaging methods providing information related to collagen in the skin. PS-OCT provides birefringence information which is due to the collagen composition of the skin. SHG microscopy visualizes collagen fibers in the skin based on their SHG property. These two modalities have been applied to the same skin pathologies associated with collagen changes, but their relati...

  7. Measurement of tissue optical properties with optical coherence tomography: Implication for noninvasive blood glucose concentration monitoring

    Larin, Kirill V.

    Approximately 14 million people in the USA and more than 140 million people worldwide suffer from diabetes mellitus. The current glucose sensing technique involves a finger puncture several times a day to obtain a droplet of blood for analysis. There have been enormous efforts by many scientific groups and companies to quantify glucose concentration noninvasively using different optical techniques. However, these techniques face limitations associated with low sensitivity, accuracy, and insufficient specificity of glucose concentrations over a physiological range. Optical coherence tomography (OCT), a new technology, is being applied for noninvasive imaging in tissues with high resolution. OCT utilizes sensitive detection of photons coherently scattered from tissue. The high resolution of this technique allows for exceptionally accurate measurement of tissue scattering from a specific layer of skin compared with other optical techniques and, therefore, may provide noninvasive and continuous monitoring of blood glucose concentration with high accuracy. In this dissertation work I experimentally and theoretically investigate feasibility of noninvasive, real-time, sensitive, and specific monitoring of blood glucose concentration using an OCT-based biosensor. The studies were performed in scattering media with stable optical properties (aqueous suspensions of polystyrene microspheres and milk), animals (New Zealand white rabbits and Yucatan micropigs), and normal subjects (during oral glucose tolerance tests). The results of these studies demonstrated: (1) capability of the OCT technique to detect changes in scattering coefficient with the accuracy of about 1.5%; (2) a sharp and linear decrease of the OCT signal slope in the dermis with the increase of blood glucose concentration; (3) the change in the OCT signal slope measured during bolus glucose injection experiments (characterized by a sharp increase of blood glucose concentration) is higher than that measured in the glucose clamping experiments (characterized by slow, controlled increase of the blood glucose concentration); and (4) the accuracy of glucose concentration monitoring may substantially be improved if optimal dimensions of the probed skin area are used. The results suggest that high-resolution OCT technique has a potential for noninvasive, accurate, and continuous glucose monitoring with high sensitivity.

  8. The utility of three-dimensional optical projection tomography in nerve injection injury imaging

    Cvetko, E.; Čapek, Martin; Damjanovska, M.; Reina, M. A.; Eržen, I.; Stopar-Pintarič, T.

    2015-01-01

    Roč. 70, č. 8 (2015), s. 939-947. ISSN 0003-2409 R&D Projects: GA ČR(CZ) GA13-12412S; GA MŠk(CZ) LH13028 Institutional support: RVO:67985823 Keywords : optical projection tomography * 3D nerve visualization * nerve disruption Subject RIV: EA - Cell Biology Impact factor: 3.382, year: 2014

  9. Morphological features in eyes with endophthalmitis after cataract surgery - histopathology and optical coherence tomography assessment

    Solborg Bjerrum, Søren; Prause, Jan Ulrik; Fuchs, Josefine; la Cour, Morten; Kiilgaard, Jens Folke

    2016-01-01

    PURPOSE: To assess the ocular damage that occurs in eyes with postoperative endophthalmitis after cataract surgery (PE) based on optical coherence tomography (OCT) retinal scans of PE eyes and histological specimens of eyes removed due to PE. METHODS: Case-control study and case series. Fifty-one...

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

    Yagüe-Fabra, J.A.; Tosello, Guido; Ontiveros, S.; Jiménez, R.; Rasmussen, Jeppe

    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 tactil...

  11. Combined dynamic and static optical tomography for prediction of treatment outcome in breast cancer patients

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

    2015-07-01

    We explored evidence that a combination of dynamic and static diffuse optical tomography can be used to predict treatment response in patients undergoing neo adjuvant chemotherapy. Both blood chromophore concentrations and hemodynamic signatures were measured over the 5-month course of treatment.

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

    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.

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

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

    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...

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

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

  15. Volumetric Doppler imaging of small animal brain using spectral and time domain optical coherence tomography

    Bukowska, Danuta; Grulkowski, Ireneusz; Wilczynski, Grzegorz; Tamborski, Szymon; Ruminski, Daniel; Wlodarczyk, Jakub; Szlag, Daniel; Szkulmowski, Maciej; Kowalczyk, Andrzej; Wojtkowski, Maciej

    2011-03-01

    In this paper we demonstrate applicability of Optical Coherence Tomography (OCT) for three-dimensional analysis of blood flow in brain of small animals. We proposed scanning protocols that enable receiving both qualitative and quantitative information about flow. Presented data are obtained with a laboratory high resolution and high speed Spectral OCT system. Data analysis is performed using joint Spectral and Time domain OCT.

  16. Improved quality of optical coherence tomography imaging of basal cell carcinomas using speckle reduction

    Mogensen, Mette; Jrgensen, Thomas Martini; Thrane, Lars; Nurnberg, Birgit Meinecke; Jemec, Gregor Borut Ernst

    2010-01-01

    BACKGROUND: Optical coherence tomography (OCT) is a possible imaging method for delineation of non-melanoma skin cancer. Speckle noise is the dominant noise contribution in OCT images; it limits the ability to identify cellular structures especially skin cancer. QUESTIONS ADDRESSED: This report s...

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

    Banzhaf, Christina Alette; Themstrup, Lotte; Ring, Hans Christian; Welzel, Julia; Mogensen, Mette; Jemec, Gregor Borut Ernst

    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...

  18. Optical coherence tomography and vessel diameter changes after intravitreal bevacizumab in diabetic macular oedema

    Soliman, W.; Vinten, M.; Sander, B.; Soliman, K.A.E.N.; Yehya, S.; Rahman, M.S.A.; Larsen, Michael

    2008-01-01

    injection of bevacizumab 1 mg, which was followed by two more injections at 6-week intervals. Fundus photography and optical coherence tomography (OCT) were carried out at baseline immediately before injection and at 1, 2.5 and 4 months after the first injection. Outcome measures were best corrected visual...

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

    Tschernig, T.; Thrane, Lars; Jørgensen, Thomas Martini; Thommes, J.; Pabst, R.; Yelbuz, T. M.

    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...

  20. Consensus standards for acquisition, measurement, and reporting of intravascular optical coherence tomography studies

    Tearney, Guillermo J; Regar, Evelyn; Akasaka, Takashi; Adriaenssens, Tom; Barlis, Peter; Bezerra, Hiram G; Bouma, Brett; Bruining, Nico; Cho, Jin-Man; Chowdhary, Saqib; Costa, Marco A; de Silva, Ranil; Dijkstra, Jouke; Di Mario, Carlo; Dudeck, Darius; Falk, Erling; Feldman, Marc D; Fitzgerald, Peter; Garcia, Hector Hernan Caro; Gonzalo, Nieves; Granada, Juan F; Guagliumi, Giulio; Holm, Niels Ramsing; Honda, Yasuhiro; Ikeno, Fumiaki; Kawasaki, Masanori; Kochman, Janusz; Koltowski, Lukasz; Kubo, Takashi; Kume, Teruyoshi; Kyono, Hiroyuki; Lam, Cheung Chi Simon; Lamouche, Guy; Lee, David P; Leon, Martin B; Maehara, Akiko; Manfrini, Olivia; Mintz, Gary S; Mizuno, Kyiouchi; Morel, Marie-Angéle; Nadkarni, Seemantini; Okura, Hiroyuki; Otake, Hiromasa; Pietrasik, Arkadiusz; Prati, Francesco; Räber, Lorenz; Radu, Maria D; Rieber, Johannes; Riga, Maria; Rollins, Andrew; Rosenberg, Mireille; Sirbu, Vasile; Serruys, Patrick W J C; Shimada, Kenei; Shinke, Toshiro; Shite, Junya; Siegel, Eliot; Sonada, Shinjo; Suter, Melissa; Takarada, Shigeho; Tanaka, Atsushi; Terashima, Mitsuyasu; Troels, Thim; Uemura, Shiro; Ughi, Giovanni J; van Beusekom, Heleen M M; van der Steen, Antonius F W; van Es, Gerrit-Ann; van Soest, Gijs; Virmani, Renu; Waxman, Sergio; Weissman, Neil J; Weisz, Giora

    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...

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

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

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

    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.

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

    Unterhuber, A.; Povaay, B.; Müller, André; Jensen, Ole Bjarlin; Duelk, M.; Le, T.; Petersen, Paul Michael; Velez, C.; Esmaeelpour, M.; Andersen, Peter E.; Drexler, W.

    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...... eye segment or eyes with increased choroidal thickness....

  4. Diabetic macular oedema quantified with spectral-domain optical coherence tomography

    Hodzic-Hadzibegovic, Delila; Sander, Birgit A; Lund-Andersen, Henrik

    2015-01-01

    PURPOSE: To characterize frequency, morphological cause and time-dependent change of boundary line artefacts in optical coherence tomography (OCT) examinations of centre-involved diabetic macular oedema (ciDME) patients who underwent ranibizumab treatment with 1-year follow-up and to evaluate the...

  5. Application of Optical Coherence Tomography (OCT) for Diagnosis of Caries, Cracks, and Defects of Restorations

    Shimada, Yasushi; Sadr, Alireza; Sumi, Yasunori; Tagami, Junji

    2015-01-01

    Optical coherence tomography (OCT) is a noninvasive technique providing cross-sectional images of a tooth structure. This review describes the use of OCT for detecting dental caries, tooth fractures, and interfacial gaps in intraoral restorations. OCT can be a reliable and an accurate method and a safer alternative to X-ray radiography.

  6. Relation between quantum tomography and optical Fresnel transform

    Fan, Hong-yi; Hu, Li-yun

    2008-01-01

    Corresponding to optical Fresnel transformation characteristic of ray transfer matrix elements (A;B;C;D); AD-BC = 1, there exists Fresnel operator F(A;B;C;D) in quantum optics, we show that under the Fresnel transformation the pure position density |x>_rs,rs__rs,rs_ is just the wave function of its Fresnel transformed state F|phi>, i.e. rs_= . Similarly, we find F|p>_rs,rs_

  7. Test target for characterizing 3D resolution of optical coherence tomography

    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.

  8. Smart optical coherence tomography for ultra-deep imaging through highly scattering media

    Badon, Amaury; Lerosey, Geoffroy; Boccara, Albert C; Fink, Mathias; Aubry, Alexandre

    2015-01-01

    Multiple scattering of waves in disordered media is a nightmare whether it be for detection or imaging purposes. The best approach so far to get rid of multiple scattering is optical coherence tomography. It basically combines confocal microscopy and coherence time-gating to discriminate ballistic photons from a predominant multiple scattering background. Nevertheless, the imaging depth range remains limited to 1 mm at best in human soft tissues. Here we propose a matrix approach of optical imaging to push back this fundamental limit. By combining a matrix discrimination of ballistic waves and iterative time-reversal, we show both theoretically and experimentally an extension of the imaging-depth limit by at least a factor two compared to optical coherence tomography. In particular, the reported experiment demonstrates imaging through a strongly scattering layer from which only one reflected photon over 1000 billion is ballistic. This approach opens a new route towards ultra-deep tissue imaging.

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

    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.

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

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

    2010-07-01

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

  11. Hand scanning optical coherence tomography imaging using encoder feedback.

    Iftimia, Nicusor; Maguluri, Gopi; Chang, Ernest W; Chang, Shing; Magill, John; Brugge, William

    2014-12-15

    We present a new method for generating micron-scale OCT images of interstitial tissue with a hand scanning probe and a linear optical encoder that senses probe movement relative to a fixed reference point, i.e., tissue surface. Based on this approach, we demonstrate high resolution optical imaging of biological tissues through a very long biopsy needle. Minor artifacts caused by tissue noncompliance are corrected using a software algorithm which detects the simple repetition of the adjacent A-scans. This hand-scanning OCT imaging approach offers the physician the freedom to access imaging sites of interest repeatedly. PMID:25503002

  12. In vivo imaging of zebrafish from embryo to adult stage with optical projection tomography

    Bassi, Andrea; Fieramonti, Luca; D'Andrea, Cosimo; Valentini, Gianluca; Cubeddu, Rinaldo; De Silvestri, Sandro; Cerullo, Giulio; Foglia, Efrem; Cotelli, Franco

    2013-02-01

    Optical Projection Tomography (OPT) is a three dimensional imaging technique that is particularly suitable for studying millimeter sized biological samples and organisms. Similarly to x-ray computed tomography, OPT is based on the acquisition of a sequence of images taken through the sample at many angles (projections). Assuming the linearity of the optical absorption process, the projections are combined to reconstruct the 3-D volume of the sample, typically using a filtered back-projection algorithm. OPT has been applied to in-vivo imaging of zebrafish (Danio rerio). The instrument and the protocol for in vivo imaging of zebrafish embryos and juvenile specimens are described. Light scattering remains a challenge for in vivo OPT, especially when samples at the upper size limit, like zebrafish at the adult stage, are under study. We describe Time-Gated Optical Projection Tomography (TGOPT), a technique able to reconstruct adult zebrafish internal structures by counteracting the scattering effects through a fast time-gate. The time gating mechanism is based on non-linear optical upconversion of an infrared ultrashort laser pulse and allows the detection of quasi-ballistic photons within a 100 fs temporal gate. This results in a strong improvement in contrast and resolution with respect to conventional OPT. Artifacts in the reconstructed images are reduced as well. We show that TGOPT is suited for imaging the skeletal system and nervous structures of adult zebrafish.

  13. Fluorescence-enhanced optical tomography in small volume: Telegrapher and Diffusion models

    Ranadhyr Roy

    2011-08-01

    Full Text Available Small animal fluorescence-enhanced optical tomography has possibility for restructuring drug discovery and preclinical investigation of drug candidates. However, accurate modeling of photon propagation in small animals is critical to quantitatively obtain accurate tomographic images. The diffusion approximation is commonly used for biomedical optical diagnostic techniques in turbid large media where absorption is low compared to scattering system. Unfortunately, this approximation has significant limitations to accurately predict radiative transport in turbid small media and also in a media where absorption is high compared to scattering systems. A radiative transport equation (RTE is best suited for photon propagation in human tissues. However, such models are quite expensive computationally. To alleviate the problems of the high computational cost of RTE and inadequacies of the diffusion equation in a small volume, we use telegrapher equation (TE in the frequency domain for fluorescence-enhanced optical tomography problems. The telegrapher equation can accurately and efficiently predict ballistic as well as diffusion-limited transport regimes which could simultaneously exist in small animals. The accuracy of telegrapher-based model is tested by comparing with the diffusion-based model using stimulated data in a small volume. This work demonstrates the use of the telegrapher-based model in small animal optical tomography problems.

  14. Spectral Domain Optical Coherence Tomography in Simple Retina Pigment Epithelium Hamartoma

    Melis Palamar Onay

    2012-03-01

    Full Text Available To report the spectral-domain optical coherence tomographic findings in a case of a simple hamartoma of the retinal pigment epithelium. A 55-year-old female patient with simple hamartoma of the retinal pigment epithelium was evaluated with ultrasonography and spectraldomain optic coherence tomography. The patient was found to have a pitch-black lesion measuring one-half of the disk diameter, located at about 1 disk diameter temporal to the foveola. B-mode ultrasonogram revealed a 0.8-mm thick retinal lesion with high internal reflectivity which was consistent with simple hamartoma of the retinal pigment epithelium. Spectral-domain optical coherence tomography demonstrated an elevated lesion extending from the retinal layer toward the vitreous. The high resolution of spectral-domain optical coherence tomography allows detailed observation of the retinal pigment epithelium hamartomas and is useful in the differential diagnosis and management of pigmented fundus lesions. (Turk J Oph thal mol 2012; 42: 157-8

  15. Optical design of an optical coherence tomography and multispectral fluorescence imaging endoscope to detect early stage ovarian cancer

    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.

  16. Assessment of laser-induced acceleration effects in optical clearing of in vivo human skin by optical coherence tomography

    Zhan, Zhigang; Wei, Huajiang; Jin, Ying

    2015-02-01

    Laser irradiation is considered to be a promising innovative technology which has been developed in an attempt to increase transdermal drug delivery. In this study, a near-infrared CW diode laser (785 nm) was applied to increase permeability of glycerol solutions in human skin in vivo and improve the optical clearing efficacy. Results show that for both 15%v/v and 30%v/v glycerol, the permeability coefficient increased significantly if the detected area of the skin tissue was treated with laser irradiation before optical clearing agents (OCAs) were applied. This study based on optical coherence tomography imaging technique and optical clearing effect finds laser irradiation a new approach for enhancing the penetration of OCAs and accelerating the rate of transdermal drug delivery.

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

    Thrane, Lars; Frosz, Michael Henoch; Tycho, Andreas; Jørgensen, Thomas M.; Yura, Harold T.; Andersen, Peter E.

    2004-01-01

    values of the optical scattering properties of the different layers and the corresponding input reference values of the MC simulation was obtained, which demonstrates the feasibility of the method for in vivo applications. This is to our knowledge the first time such verification has been obtained, and......A recently developed analytical optical coherence tomography (OCT) model [Thrane et al., J. Opt. Soc. Am. A 17, 484 (2000)] allows the extraction of optical scattering parameters from OCT images, thereby permitting attenuation compensation in those images. By expanding this theoretical model, we...... have developed a new method for extracting optical scattering parameters from multilayered tissue structures in vivo. To verify this, we used a Monte Carlo (MC) OCT model as a numerical phantom to simulate the OCT signal for het-erogeneous multilayered tissue. Excellent agreement between the extracted...

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

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

    2015-06-01

    In this paper, the application of moir 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 moir fringes and the corresponding measured two flames are obtained by integrating moir and emission tomography. After that, the distribution and the brightness of the moir 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 moir 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.

  19. Reconstruction Method for Optical Tomography Based on the Linearized Bregman Iteration with Sparse Regularization.

    Leng, Chengcai; Yu, Dongdong; Zhang, Shuang; An, Yu; Hu, Yifang

    2015-01-01

    Optical molecular imaging is a promising technique and has been widely used in physiology, and pathology at cellular and molecular levels, which includes different modalities such as bioluminescence tomography, fluorescence molecular tomography and Cerenkov luminescence tomography. The inverse problem is ill-posed for the above modalities, which cause a nonunique solution. In this paper, we propose an effective reconstruction method based on the linearized Bregman iterative algorithm with sparse regularization (LBSR) for reconstruction. Considering the sparsity characteristics of the reconstructed sources, the sparsity can be regarded as a kind of a priori information and sparse regularization is incorporated, which can accurately locate the position of the source. The linearized Bregman iteration method is exploited to minimize the sparse regularization problem so as to further achieve fast and accurate reconstruction results. Experimental results in a numerical simulation and in vivo mouse demonstrate the effectiveness and potential of the proposed method. PMID:26421055

  20. Optical tomography: Development of a new medical imaging modality

    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

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

    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 ...

  2. Optical tomography for biomedical applications by digital interference holography

    We present results of imaging experiments using digital interference holography (DIH). Calibration experiments using a resolution target demonstrate an improvement of signal-to-noise ratio (SNR) with increasing number of holograms consistent with theoretical prediction. Imaging experiments on retinal tissue reveal the topography of blood vessels as well as the optical thickness profile of the retinal layer. The SNR of tissue images is comparable to that of the resolution target, implying that the imaging system is operating close to theoretical optimum

  3. Nondestructive observation of teeth post core-space using optical coherence tomography: comparison with microcomputed tomography and live images

    Minamino, Takuya; Mine, Atsushi; Matsumoto, Mariko; Sugawa, Yoshihiko; Kabetani, Tomoshige; Higashi, Mami; Kawaguchi, Asuka; Ohmi, Masato; Awazu, Kunio; Yatani, Hirofumi

    2015-10-01

    No previous reports have observed inside the root canal using both optical coherence tomography (OCT) and x-ray microcomputed tomography (?CT) for the same sample. The purpose of this study was to clarify both OCT and ?CT image properties from observations of the same root canal after resin core build-up treatment. As OCT allows real-time observation of samples, gap formation may be able to be shown in real time. A dual-cure, one-step, self-etch adhesive system bonding agent, and dual-cure resin composite core material were used in root canals in accordance with instructions from the manufacturer. The resulting OCT images were superior for identifying gap formation at the interface, while ?CT images were better to grasp the tooth form. Continuous tomographic images from real-time OCT observation allowed successful construction of a video of the resin core build-up procedure. After 10 to 12s of light curing, a gap with a clear new signal occurred at the root-core material interface, proceeding from the coronal side (6mm from the cemento-enamel junction) to the apical side of the root.

  4. Nondestructive observation of teeth post core-space using optical coherence tomography: comparison with microcomputed tomography and live images.

    Minamino, Takuya; Mine, Atsushi; Matsumoto, Mariko; Sugawa, Yoshihiko; Kabetani, Tomoshige; Higashi, Mami; Kawaguchi, Asuka; Ohmi, Masato; Awazu, Kunio; Yatani, Hirofumi

    2015-10-01

    No previous reports have observed inside the root canal using both optical coherence tomography (OCT) and x-ray microcomputed tomography (μCT) for the same sample. The purpose of this study was to clarify both OCT and μCT image properties from observations of the same root canal after resin core build-up treatment. As OCT allows real-time observation of samples, gap formation may be able to be shown in real time. A dual-cure, one-step, self-etch adhesive system bonding agent, and dual-cure resin composite core material were used in root canals in accordance with instructions from the manufacturer. The resulting OCT images were superior for identifying gap formation at the interface, while μCT images were better to grasp the tooth form. Continuous tomographic images from real-time OCT observation allowed successful construction of a video of the resin core build-up procedure. After 10 to 12 s of light curing, a gap with a clear new signal occurred at the root-core material interface, proceeding from the coronal side (6 mm from the cemento-enamel junction) to the apical side of the root. PMID:26440617

  5. Assessment of natural enamel lesions with optical coherence tomography in comparison with microfocus x-ray computed tomography.

    Espigares, Jorge; Sadr, Alireza; Hamba, Hidenori; Shimada, Yasushi; Otsuki, Masayuki; Tagami, Junji; Sumi, Yasunori

    2015-01-01

    A technology to characterize early enamel lesions is needed in dentistry. Optical coherence tomography (OCT) is a noninvasive method that provides high-resolution cross-sectional images. The aim of this study is to compare OCT with microfocus x-ray computed tomography ([Formula: see text]) for assessment of natural enamel lesions in vitro. Ten human teeth with visible white spot-like changes on the enamel smooth surface and no cavitation (ICDAS code 2) were subjected to imaging by ?CT (SMX-100CT, Shimadzu) and 1300-nm swept-source OCT (Dental SS-OCT, Panasonic Health Care). In [Formula: see text], the lesions appeared as radiolucent dark areas, while in SS-OCT, they appeared as areas of increased signal intensity beneath the surface. An SS-OCT attenuation coefficient based on Beer-Lambert law could discriminate lesions from sound enamel. Lesion depth ranged from 175 to [Formula: see text] in SS-OCT. A correlation between [Formula: see text] and SS-OCT was found regarding lesion depth ([Formula: see text], [Formula: see text]) and also surface layer thickness ([Formula: see text], [Formula: see text]). The images obtained clinically in real time using the dental SS-OCT system are suitable for the assessment of natural subsurface lesions and their surface layer, providing comparable images to a laboratory high-resolution [Formula: see text] without the use of x-ray. PMID:26158079

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

    Kupchak, Connor; Rind, Samuel; Jordaan, Bertus; Figueroa, Eden

    2015-11-01

    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 time-domain homodyne tomography and subsequently performing the technique of coherent state quantum process tomography. This method provides us with the precise knowledge of how our optical phase shift will modify any arbitrary input quantum state engineered in the mode of the reconstruction.

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

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

    2010-09-01

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

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

    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 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.

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

    Fumene Feruglio, P; Vinegoni, C; Weissleder, R [Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School, 185 Cambridge Street, Boston, MA 02114 (United States); Gros, J [Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston MA 02115 (United States); Sbarbati, A, E-mail: cvinegoni@mgh.harvard.ed [Department of Morphological and Biomedical Sciences, University of Verona, Strada Le Grazie 8, 37134 Verona (Italy)

    2010-09-21

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

  10. Breast tumor hypoxia mapping using ultrasound guided diffuse optical tomography

    Biswal, Nrusingh C.; Xu, Yan; Zhu, Quing

    2011-02-01

    Tumor hypoxia is an important indicator of tumor metabolism and tumor response to various forms of therapy. Currently, no imaging modality exists that can directly map tumor hypoxia non-invasively. We present an ultrasound guided diffuse optical imaging technique for precisely measuring the tumor oxygenation. The approach employs ultrasound structural information as a-prior knowledge for diffuse optical imaging. Hypoxia mapping is achieved using endogenous chromophores such as oxy- and deoxy- hemoglobin in the tissue. Because oxy- and deoxy- hemoglobin respond differently at different wavelengths, four different laser diodes of wavelengths 740 nm, 780 nm, 808 nm and 830 nm were used for mapping tumor hypoxia by diffuse optical imaging. Hypoxia model experiments were performed using phantoms at different oxygenation conditions (Hemoglobin oxygen saturation: 14%-92%) representing the hemoglobin oxygenation range in tissue. Targets of different sizes mimicking different development stages of breast tumors, 1.0 cm to 2.5 cm diameter in 0.5 cm steps, were tested to validate the oxygen saturation measurement accuracy with target size. The absolute deviations between the estimated hemoglobin oxygen saturations from absorption maps and oxygen measurements obtained using a pO2 electrode were less than 8% over the measured range of oxygen saturations (14% - 92%). An inhomogeneous cocentric blood phantom of deoxygenated center core and oxygenated outer shell was imaged and deoxy- and oxy- hemoglobin maps revealed corresponding distributions which correlate with inhomogeneous deoxy- and oxy- distributions frequently seen in advanced breast cancers located in the depth range of 1-3 cm.

  11. Multiple Fan-Beam Optical Tomography: Modelling Techniques

    Pang Jon Fea

    2009-10-01

    Full Text Available This paper explains in detail the solution to the forward and inverse problem faced in this research. In the forward problem section, the projection geometry and the sensor modelling are discussed. The dimensions, distributions and arrangements of the optical fibre sensors are determined based on the real hardware constructed and these are explained in the projection geometry section. The general idea in sensor modelling is to simulate an artificial environment, but with similar system properties, to predict the actual sensor values for various flow models in the hardware system. The sensitivity maps produced from the solution of the forward problems are important in reconstructing the tomographic image.

  12. Sound field reconstruction using acousto-optic tomography

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

    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...... 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...

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

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

    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...... 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...

  14. Imaginary part-based correlation mapping optical coherence tomography for imaging of blood vessels in vivo

    Chen, Chaoliang; Shi, Weisong; Gao, Wanrong

    2015-11-01

    We present an imaginary part-based correlation mapping optical coherence tomography (IMcmOCT) technique for in vivo blood vessels imaging. In the conventional correlation mapping optical coherence tomography (cmOCT) method, two adjacent frames of intensity-based structural images are correlated to extract blood flow information and the size of correlation window has to be increased to improve the signal-to-noise ratio of microcirculation maps, which may cause image blur and miss the small blood vessels. In the IMcmOCT method, the imaginary part of a depth-resolved complex analytic signal in two adjacent B-scans is correlated to reconstruct microcirculation maps. Both phantom and in vivo experiments were implemented to demonstrate that the proposed method can provide improved sensitivity for extracting blood flow information in small vessels.

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

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

    2010-11-01

    We report the use of spectral Doppler optical coherence tomography imaging (SDOCTI) for quantitative evaluation of dynamic blood circulation before and after a localized ischemic stroke in a mouse model. Rose Bengal photodynamic therapy (PDT) is used as a noninvasive means for inducing localized ischemia in cortical microvasculature of the mouse. Fast, repeated Doppler optical coherence tomography scans across vessels of interest are performed to record flow dynamic information with high temporal resolution. Doppler-angle-independent flow indices are used to quantify vascular conditions before and after the induced ischemia by the photocoagulation of PDT. The higher (or lower) flow resistive indices are associated with higher (or lower) resistance states that are confirmed by laser speckle flow index maps (of laser speckle imaging). Our in vivo experiments shows that SDOCTI can provide complementary quantified flow information that is an alternative to blood volume measurement, and can be used as a means for cortical microvasculature imaging well suited for small animal studies.

  16. Theoretical limit of spatial resolution in diffuse optical tomography using a perturbation model

    Konovalov, A B; Vlasov, V V [E.I. Zababakhin All-Russian Scientific-Research Institute of Technical Physics, Russian Federal Nuclear Centre, Snezhinsk, Chelyabinsk region (Russian Federation)

    2014-03-28

    We have assessed the limit of spatial resolution of timedomain diffuse optical tomography (DOT) based on a perturbation reconstruction model. From the viewpoint of the structure reconstruction accuracy, three different approaches to solving the inverse DOT problem are compared. The first approach involves reconstruction of diffuse tomograms from straight lines, the second from average curvilinear trajectories of photons and the third from total banana-shaped distributions of photon trajectories. In order to obtain estimates of resolution, we have derived analytical expressions for the point spread function and modulation transfer function, as well as have performed a numerical experiment on reconstruction of rectangular scattering objects with circular absorbing inhomogeneities. It is shown that in passing from reconstruction from straight lines to reconstruction using distributions of photon trajectories we can improve resolution by almost an order of magnitude and exceed the accuracy of reconstruction of multi-step algorithms used in DOT. (optical tomography)

  17. Optical coherence tomography and pathological myopia: an update of the literature.

    Cicinelli, Maria Vittoria; Pierro, Luisa; Gagliardi, Marco; Bandello, Francesco

    2015-12-01

    The purpose of this paper is to give an updated review of the last clinical entities in pathological myopia proposed by means of new generation optical coherence tomography (OCT), including enhanced depth imaging (EDI-OCT) and swept source OCT (SS-OCT). PubMed and Google engine search were carried out using the terms "pathological myopia" associated with "coherence tomography," "enhanced depth imaging," and "swept source OCT." Latest publications up to Jan 2015 about myopia-related complications, including open-angle chronic glaucoma, peripapillary retinal changes, acquired macular diseases, and choroidal neovascularization, have been reviewed. New OCT technologies have led to a greater insight in pathophysiology of high-grade myopia. However, further investigation is needed in order to prevent irreversible visual loss and optic nerve damage. PMID:26265324

  18. New developments in frequency domain optical tomography. Part I: Forward model and gradient computation

    This two part study introduces new developments in frequency domain optical tomography to take into account the collimated source direction in the computation of both the forward and the adjoint models. The solution method is based on the least square finite element method associated to the discrete ordinates method where no empirical stabilization is needed. In this first part of the study, the solution method of the forward model is highlighted with an easy handling of complex boundary condition through a penalization method. Gradient computation from an adjoint method is developed rigorously in a continuous manner through a lagrangian formalism for the deduction of the adjoint equation and the gradient of the objective function. The proposed formulation can be easily generalized to stationary and time domain optical tomography by keeping the same expressions.

  19. Quantitative analysis of the Stratus optical coherence tomography fast macular thickness map reports

    Domalpally Amitha

    2010-01-01

    Full Text Available The cross sectional optical coherence tomography images have an important role in evaluating retinal diseases. The reports generated by the Stratus fast macular thickness scan protocol are useful for both clinical and research purposes. The centerpoint thickness is an important outcome measure for many therapeutic trials related to macular disease. The data is susceptible to artifacts such as decentration and boundary line errors and could be potentially erroneous. An understanding of how the data is generated is essential before utilizing the data. This article describes the interpretation of the fast macular thickness map report, assessment of the quality of an optical coherence tomography image and identification of the artifacts that could influence the numeric data.

  20. New variational image decomposition model for simultaneously denoising and segmenting optical coherence tomography images

    Duan, Jinming; Tench, Christopher; Gottlob, Irene; Proudlock, Frank; Bai, Li

    2015-11-01

    Optical coherence tomography (OCT) imaging plays an important role in clinical diagnosis and monitoring of diseases of the human retina. Automated analysis of optical coherence tomography images is a challenging task as the images are inherently noisy. In this paper, a novel variational image decomposition model is proposed to decompose an OCT image into three components: the first component is the original image but with the noise completely removed; the second contains the set of edges representing the retinal layer boundaries present in the image; and the third is an image of noise, or in image decomposition terms, the texture, or oscillatory patterns of the original image. In addition, a fast Fourier transform based split Bregman algorithm is developed to improve computational efficiency of solving the proposed model. Extensive experiments are conducted on both synthesised and real OCT images to demonstrate that the proposed model outperforms the state-of-the-art speckle noise reduction methods and leads to accurate retinal layer segmentation.

  1. Tomography

    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

  2. Evaluation of the macular architecture of patients operated on from macula-off rhegmatogenous retinal detachment using optical coherence tomography

    With the support of optical coherence tomography, to evaluate the macular condition of the patients operated on from rhegmatogenous retinal detachment, with detached macula, who underwent buckling surgery and pars plana vitrectomy

  3. Macular Choroidal Thickness and Volume Measured by Swept-source Optical Coherence Tomography in Healthy Korean Children

    Lee, Jung Wook; Song, In Seok; Lee, Ju-hyang; Shin, Yong Un; Lim, Han Woong; Lee, Won June; LEE, BYUNG RO

    2016-01-01

    Purpose To evaluate the thickness and volume of the choroid in healthy Korean children using swept-source optical coherence tomography. Methods We examined 80 eyes of 40 healthy children and teenagers (

  4. High-resolution optical coherence tomography visualization of LASIK flap displacement

    Salaroli, Camila Haydée Rosas; Li, Yan; Huang, David

    2009-01-01

    Uneventful myopic laser in situ keratomileusis (LASIK) was performed in both eyes of a 33-year-old woman. Two weeks after LASIK, examination of the left eye revealed flap striae radiating inferonasally from the superior hinge. The flap was relifted and repositioned to remove the irregular astigmatism and reduce the striae. Before the flap was relifted, Fourier-domain optical coherence tomography (FD-OCT) showed the gap at the temporal flap, which had not been detected by biomicroscopy. After ...

  5. Time-resolved Optical Tomography instrumentation for fast 3D functional imaging.

    Jennions, D. K.

    2008-01-01

    Optical Tomography is a medical imaging method for creating three-dimensional images using near infrared light. An instrument, named MONSTIR (Multi-channel Opto-electronic Near-infrared System for Time-resolved Image Reconstruction), has been designed and built to measure the flight times of photons between two positions on the surface of the tissue being imaged. The measurements are used to generate functional images of the newborn infant brain, and to detect and classify breast disease. The...

  6. High-Definition Optical Coherence Tomography for the in vivo Detection of Demodex Mites

    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...

  7. Use of Optical Coherence Tomography to Evaluate Visual Acuity and Visual Field Changes in Dengue Fever

    Rhee, Taek Kwan; Han, Jung Il

    2014-01-01

    Dengue fever is a viral disease that is transmitted by mosquitoes and affects humans. In rare cases, dengue fever can cause visual impairment, which usually occurs within 1 month after contracting dengue fever and ranges from mild blurring of vision to severe blindness. Visual impairment due to dengue fever can be detected through angiography, retinography, optical coherence tomography (OCT) imaging, electroretinography, event electroencephalography (visually evoked potentials), and visual fi...

  8. Extracting three-dimensional orientation and tractography of myofibers using optical coherence tomography

    Gan, Yu; Fleming, Christine P.

    2013-01-01

    Abnormal changes in orientation of myofibers are associated with various cardiac diseases such as arrhythmia, irregular contraction, and cardiomyopathy. To extract fiber information, we present a method of quantifying fiber orientation and reconstructing three-dimensional tractography of myofibers using optical coherence tomography (OCT). A gradient based algorithm was developed to quantify fiber orientation in three dimensions and particle filtering technique was employed to track myofibers....

  9. Femtosecond laser micro-inscription of optical coherence tomography resolution test artifacts

    Tomlins, Peter H.; Smith, Graham N.; Woolliams, Peter D; Rasakanthan, Janarthanan; Sugden, Kate

    2011-01-01

    Optical coherence tomography (OCT) systems are becoming more commonly used in biomedical imaging and, to enable continued uptake, a reliable method of characterizing their performance and validating their operation is required. This paper outlines the use of femtosecond laser subsurface micro-inscription techniques to fabricate an OCT test artifact for validating the resolution performance of a commercial OCT system. The key advantage of this approach is that by utilizing the nonlinear absorp...

  10. Analysis of the Retinal Nerve Fiber Layer in Retinitis Pigmentosa Using Optic Coherence Tomography

    Medine Asl? Y?ld?r?m; Burak Erden; Mehmet Tetiko?lu; zlem Kuru; Mustafa Elio?lu

    2015-01-01

    Aim. To evaluate the peripapillary retinal nerve fiber layer (RNFL) changes in retinitis pigmentosa (RP) patients using spectral domain optic coherence tomography (Sd-OCT). Methods. We retrospectively examined medical records of forty-four eyes of twenty-two RP patients. The results were also compared with those of previously reported forty-four eyes of twenty-two normal subjects (controls). Records of average and four quadrants peripapillary RNFL thickness measurements using Sd-OCT were asse...

  11. Clinical cross-polarization optical coherence tomography assessment of subsurface enamel below dental resin composite restorations

    Lenton, Patricia; Rudney, Joel; FOK, ALEX; Jones, Robert S

    2014-01-01

    A newly designed intraoral swept source cross-polarization optical coherence tomography (CP-OCT) imaging system was used to examine the integrity of the subsurface enamel below resin composite restorations placed in primary teeth. CP-OCT analysis was performed using images obtained from resin composite restoration in 62 (n=62) pediatric subjects. Clinical examination was performed by a single examiner prior to CP-OCT imaging and analysis. CP-OCT images are presented using a unique combined in...

  12. White light-informed optical properties improve ultrasound-guided fluorescence tomography of photoactive protoporphyrin IX

    Flynn, Brendan P.; Dsouza, Alisha V.; Kanick, Stephen C.; Davis, Scott C.; Pogue, Brian W.

    2013-01-01

    Abstract. Subsurface fluorescence imaging is desirable for medical applications, including protoporphyrin-IX (PpIX)-based skin tumor diagnosis, surgical guidance, and dosimetry in photodynamic therapy. While tissue optical properties and heterogeneities make true subsurface fluorescence mapping an ill-posed problem, ultrasound-guided fluorescence-tomography (USFT) provides regional fluorescence mapping. Here USFT is implemented with spectroscopic decoupling of fluorescence signals (auto-fluor...

  13. Towards using spectral domain optical coherence tomography for dental wear monitoring

    M?rc?uteanu, Corina; Bradu, Adrian; Sinescu, Cosmin; Topal?, Florin I.; Negrutiu, Meda Lavinia; Podoleanu, Adrian G.

    2014-03-01

    In this paper we demonstrate that fast spectral domain optical coherence tomography imaging systems have the potential to monitor the evolution of pathological dental wear. On 10 caries free teeth, four levels of artificially defects similar to those observed in the clinic were created. After every level of induced defect, OCT scanning was performed. B-scans were acquired and 3D reconstructions were generated.

  14. Anti-Spoof Reliable Biometry of Fingerprints Using En-Face Optical Coherence Tomography

    Mohammad-Reza Nasiri-Avanaki; Alexander Meadway; Adrian Bradu; Rohollah Mazrae Khoshki; Ali Hojjatoleslami; Adrian Gh. Podoleanu

    2011-01-01

    Optical coherence tomography (OCT) is a relatively new imaging technology which can produce high-reso- lution images of three-dimensional structures. OCT has been mainly used for medical applications such as for ophthalmology and dermatology. In this study we demonstrate its capability in providing much more re- liable biometry identification of fingerprints than conventional methods. We prove that OCT can serve se- cure control of genuine fingerprints as it can detect if extra layers are pla...

  15. Optical Coherence Tomography (OCT) of Collagen in Normal Skin and Skin Fibrosis

    Babalola, Olubukola; Mamalis, Andrew; Lev-Tov, Hadar; Jagdeo, Jared

    2013-01-01

    Optical coherence tomography (OCT) is a non-invasive imaging modality that is transforming clinical diagnosis in dermatology and other medical fields. OCT provides a cross-sectional evaluation of the epidermis and dermis and allows in vivo imaging of skin collagen. Upregulated collagen content is a key feature of fibrotic skin diseases. These diseases are often managed by the practitioners subjective assessment of disease severity and response to therapies. The purpose of this review is to p...

  16. Using optical coherence tomography to quantify biofilm structure and mass transfer in combination with mathematical modeling

    Li, Chunyan

    2015-01-01

    The evolution of biofilm structure on the carriers used in moving bed biofilm reactor was investigated by means of optical coherence tomography and biofilm image analysis. A method was developed by combining biofilm imaging and mathematical modeling to study the mass transfer characteristics in the vicinity of biofilm surface. The method was further used to examine the effect of the deposition of organic particle at biofilm surface on the mass transfer from bulk liquid into biofilms.

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

    Banzhaf, Christina Alette; Themstrup, Lotte; Ring, Hans Christian; Welzel, Julia; Mogensen, Mette; Jemec, Gregor Borut Ernst

    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 ...

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

    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...

  19. Pathogenesis of the dry eye syndrome observed by optical coherence tomography in vitro

    Kray, Oya; Lenz, Markus; Spöler, Felix; Kray, Stefan; Kurz, Heinrich

    2011-06-01

    Three dimensional optical coherence tomography (OCT) is introduced as a valuable tool to analyze the pathogenesis of corneal diseases. Here, OCT in combination with a novel in vitro model for the dry eye syndrome enables an improved understanding of the underlying damaging process of the ocular surface. En-face OCT projections indicate a deep structural damage of the epithelium and anterior stroma by osmotic forces.

  20. Enhanced Depth Imaging Optical Coherence Tomography of Precursor Cell Leukemic Choroidopathy Before and After Chemotherapy

    Murtaza K Adam; Pitcher, John D.; Shields, Carol L.; Maguire, Joseph I.

    2015-01-01

    Serous retinal detachment (SRD) can be the initial manifestation of leukemia. Herein, we explore the retinal and choroidal features on enhanced depth imaging optical coherence tomography (EDI-OCT) of SRD in a patient with undiagnosed leukemia. A 23-year-old male developed blurred visual acuity of 20/200 in the right eye oculus dexter (OD) and 20/200 in the left eye oculus sinister (OS). Funduscopically, he manifested serous macular detachment in both eyes oculi uterque (OU) without hemorrhagi...

  1. In Vivo Confocal Microscopy and Anterior Segment Optic Coherence Tomography Findings in Ocular Ochronosis

    Elif Demirkilinc Biler; Suzan Guven Yilmaz; Melis Palamar; Pedram Hamrah; Afsun Sahin

    2015-01-01

    Purpose. To report clinical and in vivo confocal microscopy (IVCM) findings of two patients with ocular ochronosis secondary due to alkaptonuria. Materials and Methods. Complete ophthalmologic examinations, including IVCM (HRT II/Rostock Cornea Module, Heidelberg, Germany), anterior segment optical coherence tomography (AS-OCT) (Topcon 3D spectral-domain OCT 2000, Topcon Medical Systems, Paramus, NJ, USA), corneal topography (Pentacam, OCULUS Optikgeräte GmbH, Wetzlar, Germany), and anterior ...

  2. Polarization sensitive optical coherence tomography of melanin provides intrinsic contrast based on depolarization

    Baumann, Bernhard; Baumann, Stefan O.; Konegger, Thomas; Pircher, Michael; Götzinger, Erich; Schlanitz, Ferdinand; Schütze, Christopher; Sattmann, Harald; Litschauer, Marco; Schmidt-Erfurth, Ursula; Hitzenberger, Christoph K.

    2012-01-01

    Polarization sensitive optical coherence tomography (PS-OCT) is a functional extension of OCT. In addition to imaging based on tissue reflectivity, PS-OCT also enables depth-resolved mapping of sample polarization properties such as phase-retardation, birefringent axis orientation, Stokes vectors, and degree of polarization uniformity (DOPU). In this study, PS-OCT was used to investigate the polarization properties of melanin. In-vitro measurements in samples with varying melanin concentratio...

  3. Assessment and in vivo scoring of murine experimental autoimmune uveoretinitis using optical coherence tomography

    Chu, C J; Herrmann, P.; Carvalho, L. S.; Liyanage, S. E.; Bainbridge, J. W.; Ali, R. R.; Dick, A. D.; Luhmann, U. F.

    2013-01-01

    Despite advances in clinical imaging and grading our understanding of retinal immune responses and their morphological correlates in experimental autoimmune uveoretinitis (EAU), has been hindered by the requirement for post-mortem histology. To date, monitoring changes occurring during EAU disease progression and evaluating the effect of therapeutic intervention in real time has not been possible. We wanted to establish whether optical coherence tomography (OCT) could detect intraretinal chan...

  4. Repeated, noninvasive, high resolution spectral domain optical coherence tomography imaging of zebrafish embryos

    Kagemann, Larry; Ishikawa, Hiroshi; Zou, Jian; Charukamnoetkanok, Puwat; Wollstein, Gadi; Townsend, Kelly A.; Gabriele, Michelle L.; Bahary, Nathan; Wei, Xiangyun; Fujimoto, James G.; Schuman, Joel S.

    2008-01-01

    Purpose To demonstrate a new imaging method for high resolution spectral domain optical coherence tomography (SD-OCT) for small animal developmental imaging. Methods Wildtype zebrafish that were 24, 48, 72, and 120 h post fertilization (hpf) and nok gene mutant (48 hpf) embryos were imaged in vivo. Three additional embryos were imaged twice, once at 72 hpf and again at 120 hpf. Images of the developing eye, brain, heart, whole body, proximal yolk sac, distal yolk sac, and tail were acquired. ...

  5. Quantitative optical coherence tomography angiography of vascular abnormalities in the living human eye

    Jia, Yali; Bailey, Steven T.; Hwang, Thomas S.; McClintic, Scott M.; Simon S. Gao; Pennesi, Mark E.; Flaxel, Christina J.; Lauer, Andreas K.; Wilson, David J; Hornegger, Joachim; Fujimoto, James G.; Huang, David

    2015-01-01

    Retinal vascular diseases are a leading cause of blindness. Optical coherence tomography (OCT) has become the standard imaging modality for evaluating fluid accumulation in these diseases and for guiding treatment. However, fluorescein angiography (FA) is still required for initial evaluation of retinal ischemia and choroidal neovascularization, which are not visible in conventional structural OCT. The limitations of FA include poor penetration of fluorescence through blood and pigment, inabi...

  6. Rapid evaluation of fresh ex vivo kidney tissue with full-field optical coherence tomography

    Manu Jain; Robinson, Brian D; Bekheit Salamoon; Olivier Thouvenin; Claude Boccara; Sushmita Mukherjee

    2015-01-01

    Background: Full-field optical coherence tomography (FFOCT) is a real-time imaging technique that rapidly generates images reminiscent of histology without any tissue processing, warranting its exploration for evaluation of ex vivo kidney tissue. Methods: Fresh tissue sections from tumor and adjacent nonneoplastic kidney (n = 25 nephrectomy specimens; clear cell renal cell carcinoma (CCRCC) = 12, papillary RCC (PRCC) = 4, chromophobe RCC (ChRCC) = 4, papillary urothelial carcinoma (PUC) = 1, ...

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

    Oldenburg, Amy L.; Boppart, Stephen A.

    2010-01-01

    We present a new method for performing dynamic elastography of soft tissue samples. By sensing nanoscale displacements with optical coherence tomography, a chirped, modulated force is applied to acquire the mechanical spectrum of a tissue sample within a few seconds. This modulated force is applied via magnetic nanoparticles, named ‘nanotransducers’, which are diffused into the tissue, and which contribute negligible inertia to the soft tissue mechanical system. Using this novel system, we ob...

  8. Digital Algorithm for Dispersion Correction in Optical Coherence Tomography for Homogeneous and Stratified Media

    Marks, Daniel L.; Oldenburg, Amy L.; Reynolds, J. Joshua; Boppart, Stephen A.

    2003-01-01

    The resolution of optical coherence tomography (OCT) often suffers from blurring caused by material dispersion. We present a numerical algorithm for computationally correcting the effect of material dispersion on OCT reflectance data for homogeneous and stratified media. This is experimentally demonstrated by correcting the image of a polydimethyl siloxane microfludic structure and of glass slides. The algorithm can be implemented using the fast Fourier transform. With broad spectral bandwidths and highly dispersive media or thick objects, dispersion correction becomes increasingly important.

  9. Design and Implementation of a Custom Built Optical Projection Tomography System

    Wong, Michael D.; Dazai, Jun; Walls, Johnathon R.; Gale, Nicholas W; Henkelman, R. Mark

    2013-01-01

    Optical projection tomography (OPT) is an imaging modality that has, in the last decade, answered numerous biological questions owing to its ability to view gene expression in 3 dimensions (3D) at high resolution for samples up to several cm3. This has increased demand for a cabinet OPT system, especially for mouse embryo phenotyping, for which OPT was primarily designed for. The Medical Research Council (MRC) Technology group (UK) released a commercial OPT system, constructed by Skyscan, cal...

  10. Non-invasive Imaging of Retinal Degeneration in Small Animals Using Fourier Domain Optical Coherence Tomography

    Xu, Jing

    2009-01-01

    A prototype spectrometer based on Fourier Domain Optical Coherence Tomography (FD OCT) system was used as a non-invasive depth resolved medical imaging tool for diagnostic visualization of the retinal structures in vivo. This thesis investigated so-called Spectral Domain (SD) OCT to detect and monitor pathological signs of retinal degeneration in small animals such as mice, rats and Xenopus laevis larvae. Non-invasive SD OCT imaging was validated against invasive retinal cross sectional image...

  11. Precise measurement of volume of eccrine sweat gland in mental sweating by optical coherence tomography

    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.

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

    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.

  13. Objective assessment of symptomatic vitreous floaters using optical coherence tomography: a case report

    Kennelly, Kevin Patrick; Morgan, James Plunkett; Keegan, David Jude; Connell, Paul Patrick

    2015-01-01

    Background Vitrectomy for symptomatic vitreous floaters carries significant risks. Justification of surgery is difficult, particularly in healthy eyes with normal visual acuity and without a posterior vitreous detachment. This is the first reported case of optical coherence tomography being utilized to objectively assess the impact of a vitreous opacity on the macula. Case presentation A 37-year-old Caucasian female complained of the sudden onset of a ring-like floater in the central visual f...

  14. Compressive sensing with dispersion compensation on non-linear wavenumber sampled spectral domain optical coherence tomography

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

    2013-01-01

    We propose a novel compressive sensing (CS) method on spectral domain optical coherence tomography (SDOCT). By replacing the widely used uniform discrete Fourier transform (UDFT) matrix with a new sensing matrix which is a modification of the non-uniform discrete Fourier transform (NUDFT) matrix, it is shown that undersampled non-linear wavenumber spectral data can be used directly in the CS reconstruction. Thus k-space grid filling and k-linear mask calibration which were proposed to obtain ...

  15. Neoatherosclerosis causing edge in-stent restenosis: optical coherence tomography findings.

    Alfonso, F; Restrepo, J; Cuesta, J; Bastante, T; Rivero, F; Benedicto, A

    2015-05-01

    A patient presenting with 'edge' in-stent restenosis 12 years after the implantation of a bare-metal stent in the mid-left anterior descending coronary artery is described. Optical coherence tomography disclosed the presence of ruptured neoatherosclerosis at the stent edge. The value of this imaging technique to unravel this unique underlying anatomic substrate is discussed. The therapy of choice for patients presenting with edge in-stent restenosis (ISR) is reviewed. PMID:25911014

  16. Multilayer thin-film phantoms for axial contrast transfer function measurement in optical coherence tomography

    Agrawal, Anant; Chen, Chao-Wei; Baxi, Jigesh; Chen, Yu; Pfefer, T Joshua

    2013-01-01

    In optical coherence tomography (OCT), axial resolution is one of the most critical parameters impacting image quality. It is commonly measured by determining the point spread function (PSF) based on a specular surface reflection. The contrast transfer function (CTF) provides more insights into an imaging system’s resolving characteristics and can be readily generated in a system-independent manner, without consideration for image pixel size. In this study, we developed a test method for dete...

  17. Intraoperative Optical Coherence Tomography Using the RESCAN 700: Preliminary Results in Collagen Crosslinking

    Natasha Pahuja; Rohit Shetty; Chaitra Jayadev; Rudy Nuijts; Bharath Hedge; Vishal Arora

    2015-01-01

    Purpose. To compare the penetration of riboflavin using a microscope-integrated real time spectral domain optical coherence tomography (ZEISS OPMI LUMERA 700 and ZEISS RESCAN 700) in keratoconus patients undergoing accelerated collagen crosslinking (ACXL) between epithelium on (epi-on) and epithelium off (epi-off). Methods. Intraoperative images were obtained during each of the procedures. Seven keratoconus patients underwent epi-on ACXL and four underwent epi-off ACXL. A software tool was de...

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

    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...

  19. Optical coherence tomography for the identification of musculoskeletal structures of the spine: a pilot study

    Beaudette, Kathy; Strupler, Mathias; Benboujja, Fouzi; Parent, Stefan; Aubin, Carl-Eric; Boudoux, Caroline

    2012-01-01

    Adolescent idiopathic scoliosis (AIS) is a complex three-dimensional deformity of the spine requiring in severe cases invasive surgery. Here, we explore the potential of optical coherence tomography (OCT) as a guiding tool for novel fusionless minimally invasive spinal surgeries on an ex vivo porcine model. We show that OCT, despite its limited penetration depth, may be used to precisely locate structures such as growth plate, bone and intervertebral disk using relative attenuation coefficien...

  20. Fast retinal layer segmentation of spectral domain optical coherence tomography images

    Zhang, Tianqiao; Song, Zhangjun; Wang, Xiaogang; Zheng, Huimin; Jia, Fucang; Wu, Jianhuang; Li, Guanglin; Hu, Qingmao

    2015-09-01

    An approach to segment macular layer thicknesses from spectral domain optical coherence tomography has been proposed. The main contribution is to decrease computational costs while maintaining high accuracy via exploring Kalman filtering, customized active contour, and curve smoothing. Validation on 21 normal volumes shows that 8 layer boundaries could be segmented within 5.8 s with an average layer boundary error retinal layer boundaries.

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

    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...

  2. Mapping Molecular Agents Distributions in Whole Mice Hearts Using Born-Normalized Optical Projection Tomography

    Feruglio, Paolo Fumene; Razansky, Daniel; Gorbatov, Rostic; Ntziachristos, Vasilis; Sbarbati, Andrea; Vinegoni, Claudio; Nahrendorf, Matthias; Weissleder, Ralph

    2012-01-01

    To date there is a lack of tools to map the spatio-temporal dynamics of diverse cells in experimental heart models. Conventional histology is labor intensive with limited coverage, whereas many imaging techniques do not have sufficiently high enough spatial resolution to map cell distributions. We have designed and built a high resolution, dual channel Born-normalized near-infrared fluorescence optical projection tomography system to quantitatively and spatially resolve molecular agents distr...

  3. Blunt ocular trauma at the posterior pole in optical coherence tomography and fluorescein angiography

    Blunt ocular trauma at the posterior pole may involve a variety of retinal structures. We examined the most frequent retinal trauma (choroidal folds, commotion retinae, choroidal rupture, valsalva retinopathy, PPE-tears, Purtscher's Retinopathy etc.) by optical coherence tomography (OCT). The damaged pre-, intra- or subretinal structures were clearly visible. The OCT is during acute and chronic phases of different traumatic events an important diagnostic tool. (author)

  4. Two-dimensional micro-displacement measurement for laser coagulation using optical coherence tomography

    Kurokawa, Kazuhiro; Makita, Shuichi; Hong, Young-Joo; Yasuno, Yoshiaki

    2014-01-01

    To improve the reproducibility of photocoagulation, the ability to quantitatively monitor the thermal change of laser-irradiated retinal tissue is required. Recently, optical coherence tomography has enabled non-invasive and non-contact monitoring of the tissue structural changes during laser irradiation. To further improve the capability of this technique, a method is proposed to measure tissue displacement by simultaneously using Doppler phase shifts and correlation coefficients. The theore...

  5. Imaging laser irradiated enamel surfaces with polarization sensitive optical coherence tomography

    Hsu, Dennis J.; Darling, Cynthia L; Fried, Daniel

    2008-01-01

    Several studies have shown that lasers can be used to modify the surface morphology and chemical composition of tooth enamel to render it less soluble. Other studies have shown that Polarization Sensitive Optical Coherence Tomography (PS-OCT) can be used to non-destructively measure the efficacy of fluoride in inhibiting the development of artificial caries lesions. The purpose of this study was to determine if PS-OCT can be used to measure inhibition of enamel demineralization after CO2 lase...

  6. IN VIVO FIBER BASED HIGH SPEED OPTICAL COHERENCE TOMOGRAPHY IMAGES OF HUMAN FINGER

    S. Kumari

    2011-08-01

    Full Text Available A High Speed Optical Coherence Tomography (OCT system based on single mode fiber which can capture eight images per second was used to acquire real time OCT images of human finger in vivo. The axial resolution of the set up was estimated to be 18 ?m. With this OCT images, the thickness of stratum corneum of the fingertip, finger pad and finger nail is evaluated.

  7. Automated identification of basal cell carcinoma by polarization-sensitive optical coherence tomography

    Duan, Lian; Marvdashti, Tahereh; Lee, Alex; Tang, Jean Y; Ellerbee, Audrey K.

    2014-01-01

    We report an automated classifier to detect the presence of basal cell carcinoma in images of mouse skin tissue samples acquired by polarization-sensitive optical coherence tomography (PS-OCT). The sensitivity and specificity of the classifier based on combined information of the scattering intensity and birefringence properties of the samples are significantly higher than when intensity or birefringence information are used alone. The combined information offers a sensitivity of 94.4% and sp...

  8. Swept Source Optical Coherence Tomography based Smart Handheld Vitreoretinal Microsurgical Tool for Tremor Suppression

    Song, Cheol; Gehlbach, Peter L.; Kang, Jin U

    2012-01-01

    Microsurgeons require the ability to make precise and stable maneuvers in order to achieve surgical objectives and to minimize surgical risks during freehand microsurgical procedures. This work presents a novel common path swept source optical coherence tomography based smart surgical tool that suppresses hand tremor. It allows enhanced tool tip stabilization, more accurate targeting and may lower surgical risk. Here the one dimensional motion tremor of a surgeon’s hand is assessed by the sur...

  9. Evaluation of the Lower Punctum Parameters and Morphology Using Spectral Domain Anterior Segment Optical Coherence Tomography

    Allam, Riham S. H. M.; Ahmed, Rania A.

    2015-01-01

    Purpose. To study features of the lower punctum in normal subjects using spectral domain anterior segment optical coherence tomography (SD AS-OCT). Methods. Observational cross-sectional study that included 147 punctae (76 subjects). Punctae were evaluated clinically for appearance, position, and size. AS-OCT was used to evaluate the punctal shape, contents, and junction with the vertical canaliculus. Inner and outer diameters as well as depth were measured. Results. 24 males and 52 females (...

  10. Optical coherence tomography for assessment of microbicide safety in a small animal model

    Bell, Brent A.; Vincent, Kathleen L.; Bourne, Nigel; Vargas, Gracie; Motamedi, Massoud

    2013-01-01

    Abstract. Sensitive imaging techniques for small animals are needed to assess drug toxicity in preclinical studies. Optical coherence tomography (OCT) provides a noninvasive tool for high-resolution, depth-resolved visualization of drug-induced changes in tissue morphology. In a mouse model, we utilize OCT to assess vaginal tissue integrity following the application of topical microbicides (drugs used to prevent infection). Mice are challenged with herpes simplex virus-2 (HSV-2) to determine ...

  11. Development of a robust and fast calibration procedure for diffuse optical tomography

    Xu, Chen; Li, Hai; Yuan, Guangqian; Vavadi, Hamed; Zhu, Quing

    2015-03-01

    Near infrared (NIR) diffuse optical tomography has demonstrated great potential in the initial diagnosis of tumor and the assessment of tumor vasculature response to neoadjuvant chemotherapy. A fast and robust data processing is critical to move this technique from lab research to bench-side application. Our lab developed frequency-domain diffuse optical tomography system for clinical applications. So far, we still collect data at hospital and do the data processing off-line. In this paper, a robust calibration procedure and fast processing program were developed to overcome this limitation. Because each detection channel had its own electronic delay, the calibration procedure measured amplitude linearity and phase linearity of each channel, and formed a look-up table. The experimental measurements were corrected by the table and the fitting accuracy improved by 45.8%. To further improve the processing speed, the data collection and processing program were converted to C++ from matlab program. The overall processing speed was improved by two times. We expect the new processing program can move diffuse optical tomography one step close to bench-side clinical applications.

  12. Characteristics of polyacrylamide gel with THPC and Turnbull Blue gel dosimeters evaluated using optical tomography

    The purpose of this study was to compare characteristics of radiochromic gel – Turnbull Blue gel (TB gel) with polymer gel – polyacrylamide gel and tetrakis hydroxymethyl phosphonium chloride (PAGAT) using optical tomography. Both types of gels were examined in terms of dose sensitivity, dose response linearity and background value of spectrophotometric absorbance. The calibration curve was obtained for 60Co irradiation performed on Gammacell 220 at predefined gamma dose levels between 0 and 140 Gy for TBG and 0–15 Gy for PAGAT. To measure relative dose distributions from stereotactic irradiation, dosimeters were irradiated on Leksell Gamma Knife Perfexion. The cylindrical glass housings filled with gel were attached to the stereotactic frame. They were exposed with single shot and 16 mm collimator by 65 Gy to a 50% prescription isodose for TB gel and 4 Gy to a 50% prescription isodose for PAGAT. Evaluations of dosimeters were performed on an UV–vis Spectrophotometer Helios β and an optical cone beam homemade tomography scanner with a 16-bit astronomy CCD camera with a set of color filters. The advantages and potential disadvantages for both types of gel dosimeters were summarized. Dose distribution in central slice and measured profiles of 16 mm shot shows excellent correspondence with treatment planning system Leksell GammaPlan® for both PAGAT and Turnbull Blue gels. - highlights: • Gel dosimeters are suitable for steep dose gradient verification. • An optical tomography evaluation method is successful. • Dose response characteristics of TB gel and PAGAT gel are presented

  13. Characteristics of polyacrylamide gel with THPC and Turnbull Blue gel dosimeters evaluated using optical tomography

    Pilařová (Vávrů), Kateřina; Kozubíková, Petra; Šolc, Jaroslav; Spěváček, Václav

    2014-11-01

    The purpose of this study was to compare characteristics of radiochromic gel - Turnbull Blue gel (TB gel) with polymer gel - polyacrylamide gel and tetrakis hydroxymethyl phosphonium chloride (PAGAT) using optical tomography. Both types of gels were examined in terms of dose sensitivity, dose response linearity and background value of spectrophotometric absorbance. The calibration curve was obtained for 60Co irradiation performed on Gammacell 220 at predefined gamma dose levels between 0 and 140 Gy for TBG and 0-15 Gy for PAGAT. To measure relative dose distributions from stereotactic irradiation, dosimeters were irradiated on Leksell Gamma Knife Perfexion. The cylindrical glass housings filled with gel were attached to the stereotactic frame. They were exposed with single shot and 16 mm collimator by 65 Gy to a 50% prescription isodose for TB gel and 4 Gy to a 50% prescription isodose for PAGAT. Evaluations of dosimeters were performed on an UV-vis Spectrophotometer Helios β and an optical cone beam homemade tomography scanner with a 16-bit astronomy CCD camera with a set of color filters. The advantages and potential disadvantages for both types of gel dosimeters were summarized. Dose distribution in central slice and measured profiles of 16 mm shot shows excellent correspondence with treatment planning system Leksell GammaPlan® for both PAGAT and Turnbull Blue gels. Gel dosimeters are suitable for steep dose gradient verification. An optical tomography evaluation method is successful. Dose response characteristics of TB gel and PAGAT gel are presented.

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

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

    2013-04-01

    A fundamental question addressed in this study was the feasibility of preterm birth prediction based on a noncontact investigation of fetal membranes in situ. Although the phenomena of preterm birth and the premature rupture of the fetal membrane are well known, currently, there are no diagnostic tools for their prediction. The aim of this study was to assess whether optical coherence tomography could be used for clinical investigations of high-risk pregnancies. The thickness of fetal membranes was measured in parallel by optical coherence tomography and histological techniques for the following types of birth: normal births, preterm births without premature ruptures and births at full term with premature rupture of membrane. Our study revealed that the membrane thickness correlates with the birth type. Normal births membranes were statistically significantly thicker than those belonging to the other two groups. Thus, in spite of almost equal duration of gestation of the normal births and the births at full term with premature rupture, the corresponding membrane thicknesses differed. This difference is possibly related to previously reported water accumulation in the membranes. The optical coherence tomography results were encouraging, suggesting that this technology could be used in future to predict and distinguish between different kinds of births. PMID:23637215

  15. Laser tissue coagulation and concurrent optical coherence tomography through a double-clad fiber coupler

    Beaudette, Kathy; Baac, Hyoung Won; Madore, Wendy-Julie; Villiger, Martin; Godbout, Nicolas; Bouma, Brett E; Boudoux, Caroline

    2015-01-01

    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% mu...

  16. The modulation transfer function of an optical coherence tomography imaging system in turbid media

    In this paper we describe measurements of the contrast transfer function, modulation transfer function and point-spread function of an optical coherence tomography (OCT) imaging system through scattering layers having a dimension-less scattering depth over the range 0.2-6.9. The results were found to be insensitive to scattering density, indicating that these measurement parameters alone do not well characterize the practical imaging ability of an OCT instrument. Attenuation and increased noise floor due to optical scattering were found to be the primary imaging limit and the effect of multiple scattering on OCT resolution was negligible.

  17. Process tomography of dynamical decoupling in a dense optically trapped atomic ensemble

    Sagi, Yoav; Davidson, Nir

    2010-01-01

    Atomic ensembles have many potential applications in quantum information science. Owing to collective enhancement, working with ensembles at high densities increases the overall efficiency of quantum operations, but at the same time also increases the collision rate and leads to faster decoherence. Here we report on experiments with optically trapped 87Rb atoms demonstrating a 20-fold increase of the coherence time when a dynamical decoupling sequence with more than 200 pi-pulses is applied. We perform quantum process tomography and demonstrate that using the decoupling scheme a dense ensemble with an optical depth of 230 can be used as an atomic memory with coherence times exceeding 3 sec.

  18. Three-dimensional diffuse optical tomography of osteoarthritis: a study of 38 finger joints

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

    2009-02-01

    Our previous work has shown that near-infrared diffuse optical tomography has the potential to be a clinical tool in diagnosis of osteoarthritis. Here we report a study of 38 joints from 38 females, including 20 OA and 18 healthy joints. The quantitative results obtained show that there exists clear difference between OA and healthy joints in terms of the ratio of optical properties of the joint soft tissues to that of the associated bone. Statistic analysis of these clinical data is also presented.

  19. NONINVASIVE DIAGNOSIS OF BLADDER CANCER BY CROSS-POLARIZATION OPTICAL COHERENCE TOMOGRAPHY: A BLIND STATISTICAL STUDY

    O. S. Streltsova

    2014-07-01

    Full Text Available Whether cross-polarization (CP optical coherence tomography (OCT could be used to detect early bladder cancer was ascertained; it was compared with traditional OCT within the framework of blind (closed clinical statistical studies. One hundred and sixteen patients with local nonexophytic (flat pathological processes of the bladder were examined; 360 CP OCT images were obtained and analyzed. The study used an OCT 1300-U CP optical coherence tomographer. CP OCT showed a high (94% sensitivity and a high (84% specificity in the identification of suspected nonexophytic areas in the urinary bladder.

  20. Diagnostic value of optical coherence tomography for intracranial pressure in idiopathic intracranial hypertension

    Skau, M; Yri, H; Sander, B; Gerds, TA; Milea, D; Jensen, R

    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...

  1. Spectral Domain Optical Coherence Tomography in Simple Retina Pigment Epithelium Hamartoma

    Melis Palamar Onay; Ayşe Yağcı

    2012-01-01

    To report the spectral-domain optical coherence tomographic findings in a case of a simple hamartoma of the retinal pigment epithelium. A 55-year-old female patient with simple hamartoma of the retinal pigment epithelium was evaluated with ultrasonography and spectraldomain optic coherence tomography. The patient was found to have a pitch-black lesion measuring one-half of the disk diameter, located at about 1 disk diameter temporal to the foveola. B-mode ultrasonogram revealed a 0.8...

  2. Time resolved optical tomography of the human forearm

    Hillman, Elizabeth M. C.; Hebden, Jeremy C.; Schweiger, Martin; Dehghani, Hamid; Schmidt, Florian E. W.; Delpy, David T.; Arridge, Simon R.

    2001-04-01

    A 32-channel time-resolved optical imaging instrument has been developed principally to study functional parameters of the new-born infant brain. As a prelude to studies on infants, the device and image reconstruction methodology have been evaluated on the adult human forearm. Cross-sectional images were generated using time-resolved measurements of transmitted light at two wavelengths. All data were acquired using a fully automated computer-controlled protocol. Images representing the internal scattering and absorbing properties of the arm are presented, as well as images that reveal physiological changes during a simple finger flexion exercise. The results presented in this paper represent the first simultaneous tomographic reconstruction of the internal scattering and absorbing properties of a clinical subject using purely temporal data, with additional co-registered difference images showing repeatable absorption changes at two wavelengths in response to exercise.

  3. Versatile Wideband Balanced Detector for Quantum Optical Homodyne Tomography

    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.

  4. Optical tomography in the application of the surface feature extraction

    Li, Baosheng; Wang, Yicheng; Yang, Jiuchun

    2015-11-01

    This paper put forwards a new optical tomographic imaging system, which consists of the rotating periscope system and modulating plate with 65 slits. One-dimensional signals which are divided by modulating plate through the rotating periscope system are collected by photon detector. The paper analyzes the principle of filter back projection (FBP), and chooses the filter that fits the system. It verifies the feasibility of this system by the actual simulation. Choose the circular hole and the calibration image as the target image in scanning experiment, in result of finding that the feature of reconstruction result is obvious, but information of edges is fade. This system plays an important role in developing feature extraction of surface.

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

    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.

  6. The potential optical coherence tomography in tooth bleaching quantitative assessment

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

    2011-12-01

    In this paper, we report the outcomes from a pilot study on using OCT functional imaging method to evaluate and quantify color alteration in the human teeth in vitro. The image formations of the dental tissues without and with treatment 35% hydrogen peroxide were obtained by an OCT system at a 1310 nm central wavelength. One parameter for the quantification of optical properties from OCT measurements is introduced in our study: attenuate coefficient (μ). And the attenuate coefficient have significant decrease ( p tooth bleaching process. From the experimental results, it is found that attenuate coefficient could be useful to assess color alteration of the human tooth samples. OCT has a potential to become an effective tool for the assessment tooth bleaching. And our experiment offer a now method to evaluate color change in visible region by quantitative analysis of the infrared region information from OCT.

  7. Real-time three-dimensional optical coherence tomography image-guided core-needle biopsy system

    Kuo, Wei-Cheng; Kim, Jongsik; Shemonski, Nathan D.; CHANEY, ERIC J.; Spillman, Darold R.; BOPPART, STEPHEN A.

    2012-01-01

    Advances in optical imaging modalities, such as optical coherence tomography (OCT), enable us to observe tissue microstructure at high resolution and in real time. Currently, core-needle biopsies are guided by external imaging modalities such as ultrasound imaging and x-ray computed tomography (CT) for breast and lung masses, respectively. These image-guided procedures are frequently limited by spatial resolution when using ultrasound imaging, or by temporal resolution (rapid real-time feedba...

  8. In vivo, label-free, three-dimensional quantitative imaging of kidney microcirculation using Doppler optical coherence tomography (DOCT)

    Wierwille, Jeremiah; Andrews, Peter M.; Onozato, Maristela L; Jiang, James; Cable, Alex; Chen, Yu

    2011-01-01

    Doppler optical coherence tomography (DOCT) is a functional extension of optical coherence tomography (OCT) and is currently being employed in several clinical arenas to quantify blood flow in vivo. In this study, the objective was to investigate the feasibility of DOCT to image kidney microcirculation, specifically, glomerular blood flow. DOCT is able to capture 3D data sets consisting of a series of cross-sectional images in real time, which enables label-free and non-destructive quantifica...

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

    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 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

  10. Improvement of tissue analysis and classification using optical coherence tomography combined with Raman spectroscopy

    Liu, Chih-Hao; Qi, Ji; Lu, Jing; Wang, Shang; Wu, Chen; Shih, Wei-Chuan; Larin, Kirill V.

    2014-02-01

    Optical coherence tomography (OCT) is an optical imaging technique that is capable of performing high-resolution (approaching the histopathology level) and real-time imaging of tissues without use of contrast agents. Based on these advantages, the pathological features of tumors (in micro scale) can be identified during resection surgery. However, the accuracy of tumor margin prediction still needs to be enhanced for assisting the judgment of surgeons. In this regard, we present a two-dimensional computational method for advanced tissue analysis and characterization based on optical coherence tomography (OCT) and Raman spectroscopy (RS). The method combines the slope of OCT intensity signal and the Principal component (PC) of RS, and relies on the tissue optical attenuation and chemical ingredients for the classification of tissue types. Our pilot experiments were performed on mouse kidney, liver and small intestine. Results demonstrate the improvement of the tissue differentiation compared with the analysis only based on the OCT detection. This combined OCT/RS method is potentially useful as a novel optical biopsy technique for cancer detection.

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

    Mário L. R. Monteiro

    2008-01-01

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

  12. Quantum Process Tomography of a Room Temperature Optically-Controlled Phase Shift

    Kupchak, Connor; Rind, Samuel; Figueroa, Eden; Stony Brook University Team

    2015-05-01

    We have developed a room temperature setup capable of optically controlled phase shifts on a weak probe field. Our system is realized in a vapor of 87Rb atoms under the conditions of electromagnetically induced transparency utilizing a N-type energy level scheme coupled by three optical fields. By varying the power of the signal field, we can control the size of an optical phase shift experienced by weak coherent state pulses of ~ 1 , propagating through the vapor. We quantify the optical phase shift by measuring the process output via balanced homodyne tomography which provides us with the complete quadrature and phase information of the output states. Furthermore, we measure the output for a set of states over a subspace of the coherent state basis and gain the information to completely reconstruct our phase shift procedure by coherent state quantum process tomography. The reconstruction yields a rank-4 process superoperator which grants the ability to predict how our phase shift process will behave on an arbitrary quantum optical state in the mode of the reconstruction. Our results demonstrate progress towards room temperature systems for possible quantum gates; a key component of a future quantum processor designed to operate at room temperature. US-Navy Office of Naval Research N00141410801, National Science Foundation PHY-1404398, Natural Sciences and Engineering Research Council of Canada.

  13. Optical computer aided tomography measurements of plasma uniformity in an inductively coupled discharge

    Benck, E. C.; Roberts, J. R.

    1998-11-01

    Optical computer aided tomography (CAT) is being investigated as a potential in situ diagnostic for measuring plasma uniformity without making assumptions concerning the plasma symmetry. The presence of an opaque vacuum chamber wall severely limits the different directions from which optical emission measurements can be made of the plasma. The tomographic inversion problem with restricted optical access is being solved using Tikhonov regularization. The accuracy of this inversion process is investigated for several different observation geometries using theoretical test data generated from known distributions. Optical CAT is applied to an ICP-GEC plasma source, with all the measurements made through a single large 152 mm diameter window. Axially asymmetric plasma distributions are demonstrated as a function of gas flowrate and gas composition.

  14. Efficient trigger signal generation from wasted backward amplified stimulated emission at optical amplifiers for optical coherence tomography

    Kim Seung Taek

    2015-01-01

    Full Text Available This paper propose an optical structure to generate trigger signals for optical coherence tomography (OCT using backward light which is usually disposed. The backward light is called backward amplified stimulated emission generated from semiconductor optical amplifier (SOA when using swept wavelength tunable laser (SWTL. A circulator is applied to block undesirable lights in the SWTL instead of an isolator in common SWTL. The circulator also diverts backward amplified spontaneous lights, which finally bring out trigger signals for a high speed digitizer. The spectra of the forward lights at SOA and the waveform of the backward lights were measured to check the procedure of the trigger formation in the experiment. The results showed that the trigger signals from the proposed SWTL with the circulator was quite usable in OCT.

  15. Optical characters and texture maps of skin and the aging mechanism by use of multiphoton microscopy and optical coherence tomography

    Wu, Shulian; Li, Hui; Zhang, Xiaoman; Huang, Yudian; Xu, Xiaohui

    2012-03-01

    Cutaneous aging is a complicated biological process affecting different constituents of skin, which can be divided into two types: the chronological aging and the photo-aging. The two cutaneous aging processes often co-exist accompanying with each other. The effects are often overlapped including changes in epithelium and dermis. The degeneration of collagen is a major factor in dermal alteration with aging. In this study, multiphoton microscopy (MPM) with its high resolution imaging and optical coherence tomography (OCT) with its depth resolved imaging were used to study the anti-aging dermatology in vivo. It was attempted to make the optical parameter and texture feature to evaluate the process of aging skin using mathematical image processing. The links among optical parameter, spectrum and texture feature in collagen with aging process were established to uncover mechanism of aging skin.

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

    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 oclock (43% and 5 oclock (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 oclock 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

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

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

    2014-04-01

    IMPORTANCE Evidence is mounting that achromatopsia is a progressive retinal degeneration, and treatments for this condition are on the horizon. OBJECTIVES To categorize achromatopsia into clinically identifiable stages using spectral-domain optical coherence tomography and to describe fundus autofluorescence imaging in this condition. DESIGN, SETTING, AND PARTICIPANTS A prospective observational study was performed between 2010 and 2012 at the Edward S. Harkness Eye Institute, New York-Presbyterian Hospital. Participants included 17 patients (aged 10-62 years) with full-field electroretinography-confirmed achromatopsia. MAIN OUTCOMES AND MEASURES Spectral-domain optical coherence tomography features and staging system, fundus autofluorescence and near-infrared reflectance features and their correlation to optical coherence tomography, and genetic mutations served as the outcomes and measures. RESULTS Achromatopsia was categorized into 5 stages on spectral-domain optical coherence tomography: stage 1 (2 patients [12%]), intact outer retina; stage 2 (2 patients [12%]), inner segment ellipsoid line disruption; stage 3 (5 patients [29%]), presence of an optically empty space; stage 4 (5 patients [29%]), optically empty space with partial retinal pigment epithelium disruption; and stage 5 (3 patients [18%]), complete retinal pigment epithelium disruption and/or loss of the outer nuclear layer. Stage 1 patients showed isolated hyperreflectivity of the external limiting membrane in the fovea, and the external limiting membrane was hyperreflective above each optically empty space. On near infrared reflectance imaging, the fovea was normal, hyporeflective, or showed both hyporeflective and hyperreflective features. All patients demonstrated autofluorescence abnormalities in the fovea and/or parafovea: 9 participants (53%) had reduced or absent autofluorescence surrounded by increased autofluorescence, 4 individuals (24%) showed only reduced or absent autofluorescence, 3 patients (18%) displayed only increased autofluorescence, and 1 individual (6%) exhibited decreased macular pigment contrast. Inner segment ellipsoid line loss generally correlated with the area of reduced autofluorescence, but hyperautofluorescence extended into this region in 2 patients (12%). Bilateral coloboma-like atrophic macular lesions were observed in 1 patient (6%). Five novel mutations were identified (4 in the CNGA3 gene and 1 in the CNGB3 gene). CONCLUSIONS AND RELEVANCE Achromatopsia often demonstrates hyperautofluorescence suggestive of progressive retinal degeneration. The proposed staging system facilitates classification of the disease into different phases of progression and may have therapeutic implications. PMID:24504161

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

    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

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

    Balima, O., E-mail: ofbalima@gmail.com [Dpartement des Sciences Appliques, Universit du Qubec Chicoutimi, 555 bd de lUniversit, Chicoutimi, QC, Canada G7H 2B1 (Canada); Favennec, Y. [LTN UMR CNRS 6607 Polytech Nantes La Chantrerie, Rue Christian Pauc, BP 50609 44 306 Nantes Cedex 3 (France); Rousse, D. [Chaire de recherche industrielle en technologies de lnergie et en efficacit nergtique (t3e), cole de technologie suprieure, 201 Boul. Mgr, Bourget Lvis, QC, Canada G6V 6Z3 (Canada)

    2013-10-15

    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.

  20. Optic Disc Perfusion in Primary Open Angle and Normal Tension Glaucoma Eyes Using Optical Coherence Tomography-Based Microangiography

    Wen, Joanne C.; Zhang, Qinqin; Xin, Chen; Gupta, Divakar; Mudumbai, Raghu C.; Johnstone, Murray A.; Wang, Ruikang K.; Chen, Philip P.

    2016-01-01

    Purpose To investigate optic disc perfusion differences in normal, primary open-angle glaucoma (POAG), and normal tension glaucoma (NTG) eyes using optical microangiography (OMAG) based optical coherence tomography (OCT) angiography technique. Design Cross-sectional, observational study. Subjects Twenty-eight normal, 30 POAG, and 31 NTG subjects. Methods One eye from each subject was scanned with a 68 kHz Cirrus HD-OCT 5,000-based OMAG prototype system centered at the optic nerve head (ONH) (Carl Zeiss Meditec Inc, Dublin, CA). Microvascular images were generated from the OMAG dataset by detecting the differences in OCT signal between consecutive B-scans. The pre-laminar layer (preLC) was isolated by a semi-automatic segmentation program. Main Outcome Measures Optic disc perfusion, quantified as flux, vessel area density, and normalized flux (flux normalized by the vessel area) within the ONH. Results Glaucomatous eyes had significantly lower optic disc perfusion in preLC in all three perfusion metrics (pglaucoma. PMID:27149261

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

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

  2. A small animal time-resolved optical tomography platform using wide-field excitation

    Venugopal, Vivek

    Small animal imaging plays a critical role in present day biomedical research by filling an important gap in the translation of research from the bench to the bedside. Optical techniques constitute an emerging imaging modality which have tremendous potential in preclinical applications. Optical imaging methods are capable of non-invasive assessment of the functional and molecular characteristics of biological tissue. The three-dimensional optical imaging technique, referred to as diffuse optical tomography, provides an approach for the whole-body imaging of small animal models and can provide volumetric maps of tissue functional parameters (e.g. blood volume, oxygen saturation etc.) and/or provide 3D localization and quantification of fluorescence-based molecular markers in vivo. However, the complex mathematical reconstruction problem associated with optical tomography and the cumbersome instrumental designs limits its adoption as a high-throughput quantitative whole-body imaging modality in current biomedical research. The development of new optical imaging paradigms is thus necessary for a wide-acceptance of this new technology. In this thesis, the design, development, characterization and optimization of a small animal optical tomography system is discussed. Specifically, the platform combines a highly sensitive time-resolved imaging paradigm with multi-spectral excitation capability and CCD-based detection to provide a system capable of generating spatially, spectrally and temporally dense measurement datasets. The acquisition of such data sets however can take long and translate to often unrealistic acquisition times when using the classical point source based excitation scheme. The novel approach in the design of this platform is the adoption of a wide-field excitation scheme which employs extended excitation sources and in the process allows an estimated ten-fold reduction in the acquisition time. The work described herein details the design of the imaging platform employing DLP-based excitation and time-gated intensified CCD detection and the optimal system operation parameters are determined. The feasibility this imaging approach and accuracy of the system in reconstructing functional parameters and fluorescence markers based on lifetime contrast is established through phantom studies. As a part of the system characterization, the effect of noise in time-resolved optical tomography is investigated and propagation of system noise in optical reconstructions is established. Furthermore, data processing and measurement calibration techniques aimed at reducing the effect of noise in reconstructions are defined. The optimization of excitation pattern selection is established through a novel measurement-guided iterative pattern correction scheme. This technique referred to as Adaptive Full-Field Optical Tomography was shown to improve reconstruction performances in murine models by reducing the dynamic range in photon flux measurements on the surface. Lastly, the application of the unique attributes of this platform to a biologically relevant imaging application, referred to as Forster Resonance Energy Transfer is described. The tomographic imaging of FRET interaction in vivo on a whole-body scale is achieved using the wide-field imaging approach based on lifetime contrast. This technique represents the first demonstration of tomographic FRET imaging in small animals and has significant potential in the development of optical imaging techniques in varied applications ranging from drug discovery to in vivo study of protein-protein interaction.

  3. A laminar optical tomography system for the early cervical cancer diagnosis

    Cui, Shanshan; Jia, Mengyu; Chen, Xueying; Meng, Wei; Gao, Feng; Zhao, Huijuan

    2014-03-01

    Laminar optical tomography (LOT) is a new mesoscopic functional optical imaging technique, which is an extension of a confocal microscope and diffuse optical tomography to acquire both the coaxial and off-axis scattered light at the same time. In this paper, a LOT system with a larger detection area aiming at the in vivo detection of early cervical cancer is developed. The field of view of our system is 10 mm x 10 mm. In order to improve the image quality of the system, two methods were performed: the correction of image distortion and the restriction of returning light. The performance of the system with aperture stop was assessed by liquid phantom experiments. Comparing with the Monte Carlo simulation, the measurement results show that the average relative errors of eight different source-detector distances corresponding to 4 source points are lower than the errors of the system taking the frame of objective lens as the aperture stop by 5.7%, 4.8%, 6.1%, 6.1% respectively. Moreover, the experiment based on the phantom with specified structure and optical parameters to simulate the cervix demonstrates that the system perform well for the cervix measurement.

  4. Common Path Side Viewing Monolithic Ball Lens Probe for Optical Coherence Tomography

    Kanwarpal Singh

    2015-09-01

    Full Text Available Common path probes are highly desirable for optical coherence tomography as they reduce system complexity and cost by eliminating the need of dispersion compensation and polarization controlling optics. In this work, we demonstrate a monolithic ball lens based, common path, side viewing probe that is suitable for Fourier domain optical coherence tomography. The probe design parameters were simulated in Zemax modeling software and the simulated performance parameters were compared with experimental results. We characterized the performance of the probe by measuring its collection efficiency, resolution, and sensitivity. Our results demonstrated that with a source input power of 25 mW, we could achieve sensitivity of 100.5 dB, which is within 7 dB of the maximum possible sensitivity that could be achieved using a separate reference arm. The axial resolution of the system was found to be 15.6 m in air and the lateral resolution (full width half maximum was approximately 49 m. The probe optics were assembled in a 1 mm diameter hypotube with a 500 m inner diameter. Images of finger skin acquired using this probe demonstrated clear visualization of the stratum corneum, epidermis, and papillary dermis, along with sweat ducts.

  5. Optical tomography with the discontinuous Galerkin formulation of the radiative transfer equation in frequency domain

    Optical tomography is an inverse method of probing semi-transparent media with the help of light sources. The reconstruction of the optical properties usually employs finite volumes or continuous finite elements formulations of light transport as a forward model for the predictions. In a previous study, we have introduced a generalization of the inversion approach with finite elements formulations by using an integral form of the objective function. The novelty is that the surfaces of the detectors are taken into account in the reconstruction and compatibility is obtained for all finite element formulations. This present paper illustrates this new approach by developing a Discontinuous Galerkin formulation as a forward model for an optical tomography application in the frequency domain framework. Numerical tests are performed to gauge the accuracy of the method in recovering optical properties distribution with a gradient-based algorithm where the adjoint method is used to fastly compute the objective function gradient. It is seen that the reconstruction is accurate and can be affected by noise on the measurements as expected. Filtering of the gradient at each iteration of the reconstruction is used to cope with the ill-posed nature of the inverse problem and to improves the quality and accuracy of the reconstruction.

  6. Multi-modality optical tomography for simultaneous morphological and molecular imaging

    Yuan, Shuai; Li, Qian; Chen, Yu

    2009-11-01

    Optical coherence tomography (OCT) is an emerging medical imaging technology that can generate high resolution cross-sectional imaging (1-2 mm in depth) of tissue microstructure in situ and in real time. Fluorescence imaging provides tissue biochemical, metabolism, and molecular information by measuring fluorescence intensity or spectroscopy of either intrinsic fluorophores or exogenous contrast agents. The combination of these two modalities provides complementary morphological, functional and molecular information to comprehensively assess tissue status. There is a great interest to further extend the fluorescence imaging into tomography in order to provide depth-resolved molecular function that can be coregistered with 3-D tissue morphology provided by OCT. In this paper, we present a combined OCT and line-scanning fluorescence laminar optical tomography (FLOT) system for simultaneous 3-D morphological and molecular imaging with 10-100 ?m resolution and millimeter-scale imaging depth. Co-registration on a capillary phantom with fluorescence dye Cy5.5 using the system has been demonstrated.

  7. Nanometer resolution optical coherence tomography using broad bandwidth XUV and soft x-ray radiation

    Fuchs, Silvio; Rödel, Christian; Blinne, Alexander; Zastrau, Ulf; Wünsche, Martin; Hilbert, Vinzenz; Glaser, Leif; Viefhaus, Jens; Frumker, Eugene; Corkum, Paul; Förster, Eckhart; Paulus, Gerhard G.

    2016-01-01

    Optical coherence tomography (OCT) is a non-invasive technique for cross-sectional imaging. It is particularly advantageous for applications where conventional microscopy is not able to image deeper layers of samples in a reasonable time, e.g. in fast moving, deeper lying structures. However, at infrared and optical wavelengths, which are commonly used, the axial resolution of OCT is limited to about 1 μm, even if the bandwidth of the light covers a wide spectral range. Here, we present extreme ultraviolet coherence tomography (XCT) and thus introduce a new technique for non-invasive cross-sectional imaging of nanometer structures. XCT exploits the nanometerscale coherence lengths corresponding to the spectral transmission windows of, e.g., silicon samples. The axial resolution of coherence tomography is thus improved from micrometers to a few nanometers. Tomographic imaging with an axial resolution better than 18 nm is demonstrated for layer-type nanostructures buried in a silicon substrate. Using wavelengths in the water transmission window, nanometer-scale layers of platinum are retrieved with a resolution better than 8 nm. XCT as a nondestructive method for sub-surface tomographic imaging holds promise for several applications in semiconductor metrology and imaging in the water window. PMID:26860894

  8. Nanometer resolution optical coherence tomography using broad bandwidth XUV and soft x-ray radiation.

    Fuchs, Silvio; Rdel, Christian; Blinne, Alexander; Zastrau, Ulf; Wnsche, Martin; Hilbert, Vinzenz; Glaser, Leif; Viefhaus, Jens; Frumker, Eugene; Corkum, Paul; Frster, Eckhart; Paulus, Gerhard G

    2016-01-01

    Optical coherence tomography (OCT) is a non-invasive technique for cross-sectional imaging. It is particularly advantageous for applications where conventional microscopy is not able to image deeper layers of samples in a reasonable time, e.g. in fast moving, deeper lying structures. However, at infrared and optical wavelengths, which are commonly used, the axial resolution of OCT is limited to about 1??m, even if the bandwidth of the light covers a wide spectral range. Here, we present extreme ultraviolet coherence tomography (XCT) and thus introduce a new technique for non-invasive cross-sectional imaging of nanometer structures. XCT exploits the nanometerscale coherence lengths corresponding to the spectral transmission windows of, e.g., silicon samples. The axial resolution of coherence tomography is thus improved from micrometers to a few nanometers. Tomographic imaging with an axial resolution better than 18?nm is demonstrated for layer-type nanostructures buried in a silicon substrate. Using wavelengths in the water transmission window, nanometer-scale layers of platinum are retrieved with a resolution better than 8?nm. XCT as a nondestructive method for sub-surface tomographic imaging holds promise for several applications in semiconductor metrology and imaging in the water window. PMID:26860894

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

    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.

  10. Imaging of subcutaneous blood vessels and flow velocity profiles by optical coherence tomography

    Bonesi, M.; Proskurin, S. G.; Meglinski, I. V.

    2010-04-01

    We have applied a compact low power rapid scanning Doppler Optical Coherence Tomography system to monitor multi-dimensional velocity profiles within the complex vessels and simultaneous real-time non-invasive imaging of skin tissues morphology in vivo, in the wavelength range of 1.3-1.5 nm. Optical clearing of skin tissues has been utilized to achieve depth of OCT images up to 1.7 mm. Current approach enables applying low-power (0.4-0.5 mW) and low-noise broadband near-infrared light sources and obtaining OCT images with down to 12 μm spatial resolution. Two-dimensional time-domain OCT images of complex flow velocity profiles in blood vessel phantom and in vivo subcutaneous human skin tissues are presented. The effect of optical clearing on in vivo images is demonstrated and discussed.

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

    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.

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

    Ju-Fang Huang

    2013-08-01

    Full Text Available AIM:To explore the correlation between the retinal nerve fiber layer (RNFL thickness by using optical coherence tomography (OCT and by histological measurements in normal adult rats and optic nerve transected rats.METHODS:The RNFL thickness of 36 rats was scanned in a circle 3.46mm far from the optic disc by OCT. The two experimental groups were the normal group (n=20 rats and the optic nerve transected group (n=16 rats. The latter group included 4 groups (n=4/group surviving for 1 day, 3, 5 and 7 days. Then the RNFL thickness of the same retina area was also measured by NF-200 immunohistochemical staining method. Linear regression was used to analyze the correlation between the data obtained from these two methods.RESULTS: The RNFL thickness of normal right eyes around optic disc by OCT was 72.355.71?m and that of the left eyes was 72.655.88?m (P=0.074. The RNFL thickness of the corresponding histological section by immunohistochemistry was 37.544.05?m (right eyes and 37.384.23?m (left eyes (P=0.059. There was a good correlation between the RNFL thickness measured by OCT and that measured by histology (R2=0.8131. After optic nerve transection, the trend of the RNFL thickness was thinner with the prolonged survival time. The correlation of the thickness detected by the above two methods was approximately (R2=0.8265. Value of the RNFL thickness in rats around optic disc measured by OCT was obviously higher than that measured by common histological measurement in normal adult rats and optic nerve transected rats.CONCLUSION: The RNFL thickness measured by OCT has a strong correlation with that measured by histological method. Through OCT scanning, we found that the thickness of RNFL gradually becomes thinner in a time-dependent manner.

  13. Optical distortion correction in optical coherence tomography for quantitative ocular anterior segment by three-dimensional imaging.

    Ortiz, Sergio; Siedlecki, Damian; Grulkowski, Ireneusz; Remon, Laura; Pascual, Daniel; Wojtkowski, Maciej; Marcos, Susana

    2010-02-01

    A method for three-dimensional 3-D optical distortion (refraction) correction on anterior segment Optical Coherence Tomography (OCT) images has been developed. The method consists of 3-D ray tracing through the different surfaces, following denoising, segmentation of the surfaces, Delaunay representation of the surfaces, and application of fan distortion correction. The correction has been applied theoretically to realistic computer eye models, and experimentally to OCT images of: an artificial eye with a Polymethyl Methacrylate (PMMA) cornea and an intraocular lens (IOL), an enucleated porcine eye, and a human eye in vivo obtained from two OCT laboratory set-ups (time domain and spectral). Data are analyzed in terms of surface radii of curvature and asphericity. Comparisons are established between the reference values for the surfaces (nominal values in the computer model; non-contact profilometric measurements for the artificial eye; Scheimpflug imaging for the real eyes in vivo and vitro). The results from the OCT data were analyzed following the conventional approach of dividing the optical path by the refractive index, after application of 2-D optical correction, and 3-D optical correction (in all cases after fan distortion correction). The application of 3-D optical distortion correction increased significantly both the accuracy of the radius of curvature estimates and particularly asphericity of the surfaces, with respect to conventional methods of OCT image analysis. We found that the discrepancies of the radii of curvature estimates from 3-D optical distortion corrected OCT images are less than 1% with respect to nominal values. Optical distortion correction in 3-D is critical for quantitative analysis of OCT anterior segment imaging, and allows accurate topography of the internal surfaces of the eye. PMID:20174107

  14. Three-dimensional emission tomography of optically thick plasma for known absorption

    Three-dimensional emission tomography of plasma partially absorbing its own radiation is considered in the assumption that distribution od local absorption coefficients is known. To solve the problem relating to determination of emission local coefficients distribution under the given conditions it is suggested that algebraic algorithms are used to convert projecting matrix plotted with regard for absorption. Moreover, new algorithms NDAT and NDFBP based on expansion into a Neumann series of the product of radiation transfer operator in an absorbing medium and emission problem solution operator of transparent plasma tomography, are developed. In numerical simulation it is shown that emission filed can be restored with acceptable accuracy up to optical thickness 6-8

  15. Spontaneous Coronary Dissection: “Live Flash” Optical Coherence Tomography Guided Angioplasty

    Bento, Angela Pimenta; Fernandes, Renato Gil dos Santos Pinto; Neves, David Cintra Henriques Silva; Patrício, Lino Manuel Ribeiro; de Aguiar, José Eduardo Chambel

    2016-01-01

    Optical Coherence tomography (OCT) is a light-based imaging modality which shows tremendous potential in the setting of coronary imaging. Spontaneous coronary artery dissection (SCAD) is an infrequent cause of acute coronary syndrome (ACS). The diagnosis of SCAD is made mainly with invasive coronary angiography, although adjunctive imaging modalities such as computed tomography angiography, IVUS, and OCT may increase the diagnostic yield. The authors describe a clinical case of a young woman admitted with the diagnosis of ACS. The ACS was caused by SCAD detected in the coronary angiography and the angioplasty was guided by OCT. OCT use in the setting of SCAD has been already described and the true innovation in this case was this unique use of OCT. The guidance of angioplasty with live and short images was very useful as it allowed clearly identifying the position of the guidewires at any given moment without the use of prohibitive amounts of contrast. PMID:26989520

  16. Noninvasive monitoring of photodynamic therapy on skin neoplastic lesions using the optical attenuation coefficient measured by optical coherence tomography

    Goulart, Viviane P.; dos Santos, Moiss O.; Latrive, Anne; Freitas, Anderson Z.; Correa, Luciana; Zezell, Denise M.

    2015-05-01

    Photodynamic therapy (PDT) has become a promising alternative for treatment of skin lesions such as squamous cell carcinoma. We propose a method to monitor the effects of PDT in a noninvasive way by using the optical attenuation coefficient (OAC) calculated from optical coherence tomography (OCT) images. We conducted a study on mice with chemically induced neoplastic lesions and performed PDT on these lesions using homemade photosensitizers. The response of neoplastic lesions to therapy was monitored using, at the same time, macroscopic clinical visualization, histopathological analysis, OCT imaging, and OCT-based attenuation coefficient measurement. Results with all four modalities demonstrated a positive response to treatment. The attenuation coefficient was found to be 1.4 higher in skin lesions than in healthy tissue and it decreased after therapy. This study shows that the OAC is a potential tool to noninvasively assess the evolution of skin neoplastic lesions with time after treatment.

  17. Tri-band spectroscopic optical coherence tomography based on optical parametric amplification for lipid and vessel visualization

    Yu, Luoqin; Kang, Jiqiang; Jinata, Chandra; Wang, Xie; Wei, Xiaoming; Chan, Kin Tak; Lee, Nikki P.; Wong, Kenneth K. Y.

    2015-12-01

    A tri-band spectroscopic optical coherence tomography (SOCT) system has been implemented for visualization of lipid and blood vessel distribution. The tri-band swept source, which covers output spectrum in 1.3, 1.5, and 1.6 ?m wavelength windows, is based on a dual-band Fourier domain mode-locked laser and a fiber optical parametric amplifier. This tri-band SOCT can further differentiate materials, e.g., lipid and artery, qualitatively by contrasting attenuation coefficients difference within any two of these bands. Furthermore, ex vivo imaging of both porcine artery with artificial lipid plaque phantom and mice with coronary artery disease were demonstrated to showcase the capability of our SOCT.

  18. Optical diffraction tomography using a digital micromirror device for stable measurements of 4-D refractive index tomography of cells

    Shin, Seungwoo; Kim, Taeho; Yoon, Jonghee; Hong, Kihyun; Park, Jinah; Park, YongKeun

    2016-01-01

    Optical diffraction tomography (ODT) is an interferometric microscopy technique capable of measuring 3-D refractive index (RI) distribution of transparent samples. Multiple 2-D holograms of a sample illuminated with various angles are measured, from which 3-D RI map of the sample is reconstructed via the diffraction theory. ODT has been proved as a powerful tool for the study of biological cells, due to its non-invasiveness, label-free and quantitative imaging capability. Recently, our group has demonstrated that a digital micromirror device (DMD) can be exploited for fast and precise control of illumination beams for ODT. In this work, we systematically study the precision and stability of the ODT system equipped with a DMD and present measurements of 3-D and 4-D RI maps of various types of live cells including human red blood cells, white blood cells, hepatocytes, and HeLa cells. Furthermore, we also demonstrate the effective visualization of 3-D RI maps of live cells utilizing the measured information abou...

  19. Experimental study of z resolution in acousto-optical coherence tomography using random phase jumps on ultrasound and light

    Lesaffre, Max; Ramaz, Franois; Gross, Michel; 10.1364/AO.52.000949

    2013-01-01

    Acousto-Optical Coherence Tomography (AOCT) is a variant of Acousto Optic Imaging (also called Ultrasound modulated Optical Tomography) that makes possible to get resolution along the ultrasound propagation axis $z$. We present here new AOCT experimental results, and we study how the $z$ resolution depends on time step between phase jumps $T_\\phi$, or on the correlation length $\\Delta z$. By working at low resolution, we perform a quantitative comparison of the $z$ measurements with the theoretical Point Spread Function (PSF). We present also images recorded with different $z$ resolution, and we qualitatively show how the image quality varies with $T_\\phi$, or $\\Delta z$.

  20. Design of optical internal signalling based optical sensor for encroaching mental tomography

    Anoop Tiwari,

    2011-03-01

    Full Text Available Brain tomography is most popular technique, and has been helpful for the study of interior picturing of the body. We are going to present an fibre based integrated device consisting of interleaved arrays of gallium arsenide (GaAs , light sources and detectors operating at electro communications wavelengths(850-1300nm in the near-infrared. Such a device will allow for long-term, minimally encroaching monitoring of neural activity in freely behaving subjects, and will enable the use of structured illumination patterns to improve system performance. We evaluate the recognized accomplishment of a current commercial OIS tomography, with a proposed fibre based prototype sensor. I have also improved the temporal resolution of technique in order to observe faster hemodynamic phenomena. Also have show that near-infrared OIS imaging at wavelengths compatible with produce physiologically significant images in mice, even through skull.

  1. Concurrent diffuse optical tomography, spectroscopy and magnetic resonance imaging of breast cancer

    Ntziachristos, Vasilis

    2000-12-01

    Diffuse Optical Tomography (DOT) in the Near Infrared NIR offers the potential to perform non-invasive three- dimensional quantified imaging of large-organs in vivo. The technique targets tissue intrinsic chromophores such as oxy- and deoxy-hemoglobin and the uptake of optical contrast agents. This work considers the DOT application in studying the vascularization, hemoglobin saturation and Indocyanine Green (ICG) uptake of breast tumors in-vivo as measures of angiogenesis, blood vessel permeability and oxygen delivery and consumption. To realize this work an optical tomographer based on the single-photon-counting time- correlated technique was coupled to a Magnetic Resonance Imaging (MRI) scanner. All patients entered the study were also scheduled for biopsy; hence histopathological information was also available as the ``Gold Standard'' for the diagnostic performance. The feasibility of Diffuse Optical Tomography to image tissue in-vivo is demonstrated by direct comparison of contrast-enhanced MRI and DOT images obtained from the same breast under identical geometrical and physiological conditions. Additionally, the effect of tissue optical background heterogeneity on the imaging performance is studied using simulations. We also present optimization schemes that yield superior reconstruction and spectroscopic capacity when probing the intrinsic and extrinsic contrast of highly heterogeneous optical media. The simultaneous examination also pioneers a hybrid diagnostic modality where MRI and image-guided localized diffuse optical spectroscopy (DOS) information are concurrently available. The approach employs the MR structural and functional information as a-priori knowledge and thus improves the quantification ability of the optical method. We have employed DOS and localized DOS to quantify optical properties of tissue in two and three wavelengths and obtain functional properties of malignant, benign and normal breast lesions. Generally, cancers exhibited higher hemoglobin concentration, lower hemoglobin saturation and higher ICG uptake than normal and benign lesions. The use of DOT and localized DOS is found to be a valuable clinical tool to study tissue function. The potential to use DOT for early breast cancer detection by employing emerging classes of optical contrast agents that target highly specific biochemical cancer properties in the cellular level has also been demonstrated.

  2. Quantification of biofilm thickness using a swept source based optical coherence tomography system

    Ratheesh Kumar, M.; Murukeshan, V. M.; Seah, L. K.; Shearwood, C.

    2015-07-01

    Optical coherence tomography (OCT) is a non-invasive, non-contact optical measurement and imaging technique that relies on low coherence interferometry. Apart from bio-imaging applications, the applicability of OCT can be extended to metrological investigations because of the inherent capability of optical interferometry to perform precise measurement with high sensitivity. In this paper, we demonstrate the feasibility of OCT for the measurement of the refractive index and thickness of bacterial biofilm structures grown in a flow cell. In OCT, the depth profiles are constructed by measuring the magnitude and time delay of back reflected light from the scattering sites by means of optical interferometry. The optical distance between scattering points can be obtained by measuring the separation between the point spread functions (PSF) at the respective points in the A-scan data. The refractive index of the biofilm is calculated by measuring the apparent shift in the position of the PSF corresponding to a reference surface, caused by the biofilm growth. In our experiment, the base layer of the flow cell is used as the reference surface. It is observed that the calculated refractive index of the biofilm is close to that of water, and agrees well with the previously reported value. Finally, the physical thickness of the biofilm is calculated by dividing the optical path length by the calculated value of refractive index.

  3. Morphological changes in blood vessels produced by hyperosmotic agents and measured by optical coherence tomography.

    Vargas, Gracie; Readinger, Allison; Dozier, Susan S; Welch, Ashley J

    2003-05-01

    Optical tissue clearing by hyperosmotic chemical agents significantly increases light depth penetration in skin and may improve light-based therapeutics such as laser treatment of cutaneous vascular lesions. A feasibility study was conducted to evaluate the potential role of optical clearing by glycerol in laser treatment of cutaneous vessels. Optical imaging was performed to investigate the morphological effects of glycerol on blood vessels of skin. Blood vessels were imaged using Doppler optical coherence tomography in in vivo hamster skin treated with glycerol. Images were obtained from the subdermal side to assess morphological changes in the blood vessels caused by glycerol and from the epidermal side to assess enhanced Doppler imaging of blood vessels. Application of glycerol to the subdermis resulted in venule stasis and for prolonged treatment times, arteriole stasis. In cases where flow remained in arterioles, an improved Doppler signal was detected from blood vessels when imaging transepidermally compared with the native condition. Intensity images indicated changes in blood optical properties and improved contrast of skin cross sections after glycerol application. The observed optical and morphological effects were reversed upon hydration of the skin with phosphate-buffered saline. The combination of increased depth of light penetration and the temporary slowing or cessation of flow in blood vessels could mean improved laser treatment of vessels. PMID:12812298

  4. Detecting glucose-induced changes in in vitro and in vivo experiments with optical coherence tomography.

    Kinnunen, Matti; Myllylä, Risto; Vainio, Seppo

    2008-01-01

    Optical clearing is a well-known phenomenon. It is based on the matching of refractive indices of a bulk material and scattering particles. The same principle is also used in scattering-based optical measurements of different constituents, such as glucose. By registering changes in scattering, it is possible to evaluate changes in the concentration of a solvent. This work describes the use of optical coherence tomography (OCT) to monitor glucose-induced changes in the optical properties of samples. Intralipid, mouse skin tissue, and mice (C57BL) are used as samples. Differences between in vitro and in vivo measurement conditions, the effect of glucose on the samples' optical properties, as well as possible problems in OCT experiments are discussed. A comparison of OCT signals from mouse skin samples and mice in vivo shows that the intensity of backscattered radiation is stronger in a living animal than in cultured tissue. Moreover, the effect of glucose on the scattering properties is larger in an in vivo case than in an in vitro case. In comparison with tissue, the effect of glucose is the smallest in Intralipid. The results increase the value of using cultured tissue in developing optical sensing techniques. PMID:18465960

  5. Optical tomography for concentration and velocity profiles in two component flows

    Ibrahim, Sallehuddin; Green, Robert G.; Dutton, Ken

    2000-08-01

    Optical tomography involves the use of non-invasive optical sensors to obtain information in order to produce images of the dynamic internal characteristics of process systems. This paper presents an investigation using optical tomography suitable for determining concentration and velocity profiles in two component flows in a fluid conveying pipe. The system is capable of detecting and measuring the amount of undissolved gas in waster, or gas in oil, where the mixture is flowing in a pipe. The system employs four projections consisting of a combination of two orthogonal and two rectilinear projections. The light transmitters consists of four halogen bulbs. Each orthogonal receiver projection employs 8 sensors and each rectilinear receiver projection uses 11 sensors making a total of 38 receiver sensors. The voltage profile from the sensors gives spatial information of the flow regime. Signal processing provides time-averaged signals which will generate peripheral concentration profiles. To observe the velocity profile via cross- correlation, a second identical measurement system has been constructed. One array of sensors is positioned upstream and the other downstream in the process measurement. Cross-correlograms provide mean velocities of velocity profiles over the measurement section.

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

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

    2014-03-24

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

  7. Endoscopic optical coherence tomography with a modified microelectromechanical systems mirror for detection of bladder cancers

    Xie, Tuqiang; Xie, Huikai; Fedder, Gary K.; Pan, Yingtian

    2003-11-01

    Experimental results of a modified micromachined microelectromechanical systems (MEMS) mirror for substantial enhancement of the transverse laser scanning performance of endoscopic optical coherence tomography (EOCT) are presented. Image distortion due to buckling of MEMS mirror in our previous designs was analyzed and found to be attributed to excessive internal stress of the transverse bimorph meshes. The modified MEMS mirror completely eliminates bimorph stress and the resultant buckling effect, which increases the wobbling-free angular optical actuation to greater than 37, exceeding the transverse laser scanning requirements for EOCT and confocal endoscopy. The new optical coherence tomography (OCT) endoscope allows for two-dimensional cross-sectional imaging that covers an area of 4.2 mm 2.8 mm (limited by scope size) and at roughly 5 frames/s instead of the previous area size of 2.9 mm 2.8 mm and is highly suitable for noninvasive and high-resolution imaging diagnosis of epithelial lesions in vivo. EOCT images of normal rat bladders and rat bladder cancers are compared with the same cross sections acquired with conventional bench-top OCT. The results clearly demonstrate the potential of EOCT for in vivo imaging diagnosis and precise guidance for excisional biopsy of early bladder cancers.

  8. Radiofrequency circuit design and performance evaluation for small animal frequency-domain NIR fluorescence optical tomography

    Darne, Chinmay; Zhu, Banghe; Lu, Yujie; Tan, I.-Chih; Rasmussen, John; Sevick-Muraca, Eva M.

    2011-02-01

    Herein we report on hardware development and evaluation for frequency-domain photon migration (FDPM) technique that is miniaturized for incorporation into a micro-CT gantry for hybrid CT/NIR/PET imaging. Immunity to endogenous optical properties and enhanced contrast associated with fluorophore lifetime is inherent to the FDPM measurements and enables unique opportunities for quantitative tomography when compared to the time independent (continuous wave) approach. A miniaturized radiofrequency (rf) circuitry has been developed in our laboratory for homodyne FDPM measurements that makes use of a single 100MHz oscillator to simultaneously launch optically modulated excitation light into a small animal as well as to modulate an NIR sensitive image intensifier for collection of fluorescent signals. The use of a single oscillator not only eliminates signal drift that otherwise results from the use of multiple oscillators individually driving both source and detector, but also reduces the circuit footprint for incorporation into the CT gantry. Herein, overall system performance parameters of signal-to-noise ratio, measurement precision, spatial resolution, modulation depth (ac/dc), excitation light rejection, and clinically relevant data acquisition times are presented for mouse phantom data. Image reconstruction of phantom data and integration of circuitry for hybrid CT/NIR/PET imaging is also presented towards the ultimate validation of NIR optical tomography using PET imaging as a "gold-standard" for quantification.

  9. Tomography

    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)

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

    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.

  11. Prospectively electrocardiogram-triggered high-pitch spiral acquisition coronary computed tomography angiography for assessment of biodegradable vascular scaffold expansion: Comparison with optical coherence tomography

    BVS polymeric struts are transparent to the light so that the vessel wall contour can be easily visualized using optical coherence tomography (OCT). Therefore OCT represents a unique tool for both the evaluation of the resorption process and for the assessment of acute BVS mechanical failure. Similarly, the metal-free struts allow unrestricted coronary computed tomography angiography (CCTA), thus this non invasive method might become the gold standard for a non invasive assessment of BVS. In this case we show the ability of CCTA, performed with a low X-Ray dose, to provide a good evaluation of scaffold expansion. The quantitative measurements were in agreement with those obtained with OCT

  12. Prospectively electrocardiogram-triggered high-pitch spiral acquisition coronary computed tomography angiography for assessment of biodegradable vascular scaffold expansion: Comparison with optical coherence tomography

    D’Alfonso, Maria Grazia [Interventional Cardiology Unit University Of Florence, Heart and Vessels department, AOU Careggi, Florence (Italy); Mattesini, Alessio, E-mail: amattesini@gmail.com [Interventional Cardiology Unit University Of Florence, Heart and Vessels department, AOU Careggi, Florence (Italy); Meucci, Francesco [Interventional Cardiology Unit University Of Florence, Heart and Vessels department, AOU Careggi, Florence (Italy); Acquafresca, Manlio [Radiology Unit 4, Radiology Department, AOU Careggi, Florence (Italy); Gensini, Gian Franco; Valente, Serafina [Interventional Cardiology Unit University Of Florence, Heart and Vessels department, AOU Careggi, Florence (Italy)

    2014-11-15

    BVS polymeric struts are transparent to the light so that the vessel wall contour can be easily visualized using optical coherence tomography (OCT). Therefore OCT represents a unique tool for both the evaluation of the resorption process and for the assessment of acute BVS mechanical failure. Similarly, the metal-free struts allow unrestricted coronary computed tomography angiography (CCTA), thus this non invasive method might become the gold standard for a non invasive assessment of BVS. In this case we show the ability of CCTA, performed with a low X-Ray dose, to provide a good evaluation of scaffold expansion. The quantitative measurements were in agreement with those obtained with OCT.

  13. Evaluation of Optical Coherence Tomography as a Means of Identifying Earlier Stage Basal Cell Carcinomas while Reducing the Use of Diagnostic Biopsy

    Schwartz, Michelle; Feldman, Eleanor; Bienenfeld, Amanda; Bieber, Amy K.; Ellis, Jeffery; Alapati, Usha; Lebwohl, Mark; Siegel, Daniel M.

    2015-01-01

    Objective: To determine the diagnostic accuracy of optical coherence tomography for basal cell carcinoma and the proportion of biopsies that could be avoided if optical coherence tomography is used to rule-in surgery. Design: Multicenter, prospective, observational study. Setting: Dermatology clinics. Participants: Consecutive patients with clinically challenging pink lesions suspicious for basal cell carcinoma. Measurements: Clinical, dermoscopic, and optical coherence tomography images were obtained for all subjects. At each stage, the clinician made a diagnosis (pathology + subtype if applicable), and assessed his/her own confidence in the diagnosis. Results: Optical coherence tomography significantly (p95% confident) in 17 percent of lesions examined clinically, in 38.6 percent examined with dermoscopy, and in 70 percent examined with optical coherence tomography. With the use of optical coherence tomography in the diagnosis of basal cell carcinoma, more than 1 in 3 patients could avoid a diagnostic biopsy. Conclusion: In a population of clinically challenging lesions, optical coherence tomography improved diagnostic certainty by a factor of four over clinical examination alone and improved diagnostic accuracy by 50 percent (57-88%). The addition of optical coherence tomography to other standard assessments can improve the false-positive rate and give a high degree of certainty for ruling in a positive diagnosis for basal cell carcinoma. A reduction of 36 percent in overall biopsies could be achieved by sending high certainty basal cell carcinoma positive optical coherence tomography diagnoses straight to surgery. PMID:26557214

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

    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 μl/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.

  15. In-vivo imaging of blood flow dynamics using color Doppler optical coherence tomography

    Yazdanfar, Siavash; Rollins, Andrew M.; Izatt, Joseph A.

    2000-04-01

    Noninvasive quantitation of blood flow in the retinal micro circulation may elucidate the progression and treatment of ocular disorders including diabetic retinopathy, age-related degeneration, and glaucoma. Color Doppler optical coherence tomography was recently introduced as a technique allowing simultaneous micron-scale resolution cross-sectional imaging of tissue micro structure and blood flow in the human retina. Here, time-resolved imaging of dynamics of blood flow profiles was performed to measure cardiac pulsatility within retinal vessels. Retinal pulsatility has been shown to decrease throughout the progression of diabetic retinopathy.

  16. Observation of sound-induced corneal vibrational modes by optical coherence tomography.

    Akca, B Imran; Chang, Ernest W; Kling, Sabine; Ramier, Antoine; Scarcelli, Giuliano; Marcos, Susana; Yun, Seok H

    2015-09-01

    The mechanical stability of the cornea is critical for maintaining its normal shape and refractive function. Here, we report an observation of the mechanical resonance modes of the cornea excited by sound waves and detected by using phase-sensitive optical coherence tomography. The cornea in bovine eye globes exhibited three resonance modes in a frequency range of 50-400 Hz. The vibration amplitude of the fundamental mode at 80-120 Hz was ~8 m at a sound pressure level of 100 dB (2 Pa). Vibrography allows the visualization of the radially symmetric profiles of the resonance modes. A dynamic finite-element analysis supports our observation. PMID:26417503

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

    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.

  18. Maximum a posteriori estimator for high-contrast image composition of optical coherence tomography.

    Chan, Aaron C; Kurokawa, Kazuhiro; Makita, Shuichi; Miura, Masahiro; Yasuno, Yoshiaki

    2016-01-15

    A quantitative signal amplitude estimator for optical coherence tomography (OCT) is presented. It is based on a statistical model of OCT signal and noise, using a Bayesian maximum a posteriori (MAP) estimation framework. Multiple OCT images are used for estimation, similar to the widely utilized intensity averaging method. The estimator is less biased especially at low-intensity regions, where intensity averaging approaches the noise power and hence is biased. The estimator is applied to posterior ocular OCT images and provides high-contrast visualization of pathologies. In addition, histogram analysis objectively shows the superior performance of the estimator compared with intensity averaging. PMID:26766704

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

    Daz Daz, Jess; 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.

  20. Microfluidic volumetric flow determination using optical coherence tomography speckle: An autocorrelation approach

    De Pretto, Lucas R.; Nogueira, Gesse E. C.; Freitas, Anderson Z.

    2016-04-01

    Functional modalities of Optical Coherence Tomography (OCT) based on speckle analysis are emerging in the literature. We propose a simple approach to the autocorrelation of OCT signal to enable volumetric flow rate differentiation, based on decorrelation time. Our results show that this technique could distinguish flows separated by 3 μl/min, limited by the acquisition speed of the system. We further perform a B-scan of gradient flow inside a microchannel, enabling the visualization of the drag effect on the walls.