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1

Optical Coherence Tomography  

Science.gov (United States)

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

2

Optical Coherence Tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The review provides a concise explanation of principles of operation of different optical coherence tomography methods. A comparative analysis of their advantages and disadvantages is presented in relation to specific applications. The review will assist the reader in making an educated choice on the most suitable optical coherence tomography method to be used in a particular application.

Pier Alberto Testoni

2007-01-01

3

Doppler Optical Coherence Tomography  

Science.gov (United States)

This chapter describes Doppler optical coherence tomography (D-OCT). This is an imaging modality that combines Doppler principles with optical coherence tomography to image tissue structure and blood flow velocity simultaneously. We will review the principle and technology of D-OCT and illustrate a few examples of its applications.

Chen, Zhongping; Liu, Gangjun

4

Optical coherence tomography  

International Nuclear Information System (INIS)

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

5

Dental Optical Coherence Tomography  

Directory of Open Access Journals (Sweden)

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

Kun-Feng Lin

2013-07-01

6

Dental Optical Coherence Tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2013-01-01

7

Tracking optical coherence tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

An experimental tracking optical coherence tomography (OCT) system has been clinically tested. The prototype instrument uses a secondary sensing beam and steering mirrors to compensate for eye motion with a closed-loop bandwidth of 1 kHz and tracking accuracy, to within less than the OCT beam diameter. The retinal tracker improved image registration accuracy to <1 transverse pixel (<60 ?m). Composite OCT images averaged over multiple scans and visits show a sharp fine structure limited only ...

Ferguson, R. Daniel; Hammer, Daniel X.; Paunescu, Lelia Adelina; Beaton, Siobahn; Schuman, Joel S.

2004-01-01

8

Amplified Dispersive Optical Tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 si...

Goda, Keisuke; Solli, Daniel R.; Jalali, Bahram

2008-01-01

9

Optical Tomography in Combustion  

DEFF Research Database (Denmark)

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

Evseev, Vadim

2013-01-01

10

Amplified Dispersive Optical Tomography  

CERN Document Server

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.

Goda, Keisuke; Jalali, Bahram

2008-01-01

11

Toward Miniaturized Optical Coherence Tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Optical coherence tomography (OCT) is a widely used optical imaging technology with an increasing number of applications [1]. It has particular importance in the medical field since it can provide non-invasive, sub-micrometer resolution diagnostic images. Current OCT systems contain fiber-based or free-space bulky components which make these instruments costly. A significant decrease in the size and cost of an OCT system is possible through integrated optics. With a suitable material technolo...

Akca, B. I.; Nguyen, V. D.; Kalkman, J.; Leeuwen, T. G.; Wo?rhoff, K.; Ridder, R. M.; Pollnau, M.

2011-01-01

12

Second harmonic optical coherence tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2004-01-01

13

Anterior Segment Tomography with the Cirrus Optical Coherence Tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2012-01-01

14

Fiber optic based optical tomography sensor for monitoring plasma uniformity  

International Nuclear Information System (INIS)

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

15

Adaptive Optics in Ocular Optical Coherence Tomography  

Science.gov (United States)

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

Fernández, Enrique Josua; Artal, Pablo

16

Local Inversions in Ultrasound Modulated Optical Tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Ultrasound modulated optical tomography, also called acousto-optics tomography, is a hybrid imaging modality that aims to combine the high contrast of optical waves with the high resolution of ultrasound. We follow the model of the influence of ultrasound modulation on the light intensity measurements developed in [Bal Schotland PRL 2010]. We present sufficient conditions ensuring that the absorption and diffusion coefficients modeling light propagation can locally be unique...

Bal, Guillaume; Moskow, Shari

2013-01-01

17

MOEMS optical delay line for optical coherence tomography  

Science.gov (United States)

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

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

2014-09-01

18

Optical Coherence Tomography: Advanced Modeling  

DEFF Research Database (Denmark)

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

Andersen, Peter E.; Thrane, Lars

2013-01-01

19

Conical wavefronts in optics and tomography  

International Nuclear Information System (INIS)

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

20

Optical microcavity scanning 3D tomography.  

Science.gov (United States)

A scanning optical microcavity is exploited to achieve lens-free 3D tomography of microfluidic channels. The microcavity, powered by a low-coherence source, is realized by approaching a cleaved fiber to few tens of micrometers over the sample. The interference of scattered waves inside the cavity shapes the transverse field distribution by focusing the beam and overcoming the diffraction limit due to the optical-fiber numerical aperture. The focusing effect is also preserved in the inner layers of the sample, allowing optical 3D tomography. Analysis of microfluidic channels was demonstrated through this noninvasive technique. Although the experimental setup recalls the well-known fiber-optic Fourier-domain common-path optical coherence tomography, the proposed method has intrinsic characteristics that distinguish it from the former one. PMID:25360911

Di Donato, Andrea; Criante, Luigino; LoTurco, Sara; Farina, Marco

2014-10-01

 
 
 
 
21

Optical tomography problems at layered media  

International Nuclear Information System (INIS)

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

22

Optical coherence tomography in late solar retinopathy  

Directory of Open Access Journals (Sweden)

Full Text Available Introduction. Solar retinopathy refers to retinal injury induced by direct or indirect solar viewing. Case report. We presented a patient who had observed partial solar eclipse 51 year before. He had bilaterally decreased vision and scar of the macular region at the time of presentation. The basic diagnostic tool applied in the presented patient, optical coherence tomography, showed hyporeflexivity of the outer retina in the segment of retinal pigment epithelialphotoreceptors complex with atrophy and thinning of the foveolar region. Conclusion. Optical coherence tomography is a powerful, non-invasive diagnostic tool which can ease the diagnosis and estimate the level and nature of the macular region damage.

Jankovi? Aleksandar

2011-01-01

23

Adaptive ranging for optical coherence tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

At present, optical coherence tomography systems have a limited imaging depth or axial scan range, making diagnosis of large diameter arterial vessels and hollow organs difficult. Adaptive ranging is a feedback technique where image data is utilized to adjust the coherence gate offset and range. In this paper, we demonstrate an adaptive optical coherence tomography system with a 7.0 mm range. By matching the imaging depth to the approximately 1.5 mm penetration depth in tissue, a 3 dB sensiti...

Iftimia, N. V.; Bouma, B. E.; Boer, J. F.; Park, B. H.; Cense, B.; Tearney, G. J.

2004-01-01

24

Optical Coherence Tomography in Glaucoma  

Science.gov (United States)

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.

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

25

Optical coherence tomography of strongly scattering media  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract Optical coherence tomography (OCT) is a modern rapidly developing technique for non-invasive imaging of the internal structure of optically non-uniform objects based on the principles of low-coherent interferometry. However, multiple scattering of light in the objects under study brings distortions to the images obtained by OCT. The analysis of formation of the OCT signals is required for understanding the role of multiple scattering in this formation and providing recommendations...

Kirillin, Mikhail

2008-01-01

26

Optical coherence tomography in conjunction with bronchoscopy  

Energy Technology Data Exchange (ETDEWEB)

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)

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

27

Optical coherence tomography. Development, principles, applications  

International Nuclear Information System (INIS)

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.)

28

Blind dispersion compensation for optical coherence tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Banaszek, K.; Radunsky, As; Walmsley, Ia

2007-01-01

29

Real-time computed optical interferometric tomography  

Science.gov (United States)

High-resolution tomography is of great importance to many areas of biomedical imaging, but with it comes several apparent tradeoffs such as a narrowing depth-of-field and increasing optical aberrations. Overcoming these challenges has attracted many hardware and computational solutions. Hardware solutions, though, can become bulky or expensive and computational approaches can require high computing power or large processing times. This study demonstrates memory efficient implementations of interferometric synthetic aperture microscopy (ISAM) and computational adaptive optics (CAO) - two computational approaches for overcoming the depthof- field limitation and the effect of optical aberrations in optical coherence tomography (OCT). Traditionally requiring lengthy post processing, here we report implementations of ISAM and CAO on a single GPU for real-time in vivo imaging. Real-time, camera-limited ISAM processing enabled reliable acquisition of stable data for in vivo imaging, and CAO processing on the same GPU is shown to quickly correct static aberrations. These algorithmic advances hold the promise for high-resolution volumetric imaging in time-sensitive situations as well as enabling aberrationfree cellular-level volumetric tomography.

Shemonski, Nathan D.; Liu, Yuan-Zhi; Ahmad, Adeel; Adie, Steven G.; Carney, P. Scott; Boppart, Stephen A.

2014-03-01

30

Optical Phase-Space-Time-Frequency Tomography  

CERN Document Server

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

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

2011-01-01

31

Whole field reflectance optical tomography  

Science.gov (United States)

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.

Carbone, Nicolás A.; García, Héctor A.; di Rocco, Héctor O.; Iriarte, Daniela I.; Pomarico, Juan A.; Ranea Sandoval, Héctor F.

2011-08-01

32

Optical Coherence Tomography for Artwork Diagnostics  

International Nuclear Information System (INIS)

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

33

Optical coherence tomography for quantitative surface topography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2009-01-01

34

Adaptive optics optical coherence tomography with dynamic retinal tracking  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Adaptive optics optical coherence tomography (AO-OCT) is a highly sensitive and noninvasive method for three dimensional imaging of the microscopic retina. Like all in vivo retinal imaging techniques, however, it suffers the effects of involuntary eye movements that occur even under normal fixation. In this study we investigated dynamic retinal tracking to measure and correct eye motion at KHz rates for AO-OCT imaging. A customized retina tracking module was integrated into the sample arm of ...

Kocaoglu, Omer P.; Ferguson, R. Daniel; Jonnal, Ravi S.; Liu, Zhuolin; Wang, Qiang; Hammer, Daniel X.; Miller, Donald T.

2014-01-01

35

Optical coherence tomography used for jade industry  

Science.gov (United States)

As an expensive natural stone, jade has a worldwide market. In the jade industry, the inspection and analysis basically rely on the human eye and/or experience, which cause unavoidable waste and damage of these expensive materials. Optical Coherence Tomography (OCT) is a fundamentally new type of optical sensing technology, which can perform high resolution, cross-sectional sensing of the internal structure of materials. As jade is almost translucent to infra red light, OCT becomes an ideal tool to change the traditional procedure to volume data based machine vision system. OCT can also be used for anti-counterfeit of the expensive jade ware.

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

2010-11-01

36

Acoustically penetrable optical reflector for photoacoustic tomography.  

Science.gov (United States)

Photoacoustic tomography (PAT) detects ultrasound signals generated by the objects after absorbing illuminating photons. However, the widely used piezoelectric ultrasound transducers are generally not optically transparent, which would cause conflicts between the light illumination and the ultrasonic detection in PAT. We report a different acoustically penetrable optical reflector (APOR) concept to provide a solution to this conflict. We measured the properties of an APOR and experimentally tested its performance in a PAT system. The results demonstrated that the APOR successfully allowed the transducer to detector photoacoustic signals without affecting the light illumination. Moreover, the APOR concept can be readily implemented in various PAT systems. PMID:23839486

Deng, Zijian; Zhao, Honghong; Ren, Qiushi; Li, Changhui

2013-07-01

37

Optical coherence tomography: the past, present and future  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Optical coherence tomography is a new technology that provides an atraumatic “optical biopsy” providing both anatomical and possible histopathologic results. It has only recently been incorporated into the urological field. This paper highlights previous and prospective advances of optical coherence tomography in urology and its potential application in robotic urologic surgery.

Goel, Raj K.; Kaouk, Jihad H.

2007-01-01

38

Blood oxygenation monitoring by diffuse optical tomography  

International Nuclear Information System (INIS)

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

39

Optical tomography reconstruction based on gradient tree  

International Nuclear Information System (INIS)

The adjoint differentiation scheme was first proposed by Alexander D. Klose for the reconstruction of optical tomography [J Q S R T 2002;72:715-32]. However, the scheme proposed there can only be employed for the computation of derivatives with respect to the optical parameters on the boundary, i.e. those derivatives with respect to the internal parameters cannot be obtained there, and as a result, the correct reconstructed result cannot be obtained with the gradient based optimization algorithms. In our paper, based on the adjoint differentiation scheme, a novel algorithm based on gradient tree is proposed for the computation of the derivatives with respect to both boundary and internal optical parameters. A scheme for approximate gradient calculation is also proposed for speeding up algorithm implementation. Experimental results show that the algorithm proposed performs well and good reconstruction results can be achieved

40

Phase-conjugate optical coherence tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Quantum optical coherence tomography (Q-OCT) offers a factor-of-two improvement in axial resolution and the advantage of even-order dispersion cancellation when it is compared to conventional OCT (C-OCT). These features have been ascribed to the non-classical nature of the biphoton state employed in the former, as opposed to the classical state used in the latter. Phase-conjugate OCT (PC-OCT), introduced here, shows that non-classical light is not necessary to reap Q-OCT's a...

Erkmen, Baris I.; Shapiro, Jeffrey H.

2006-01-01

 
 
 
 
41

Spectrally encoded extended source optical coherence tomography.  

Science.gov (United States)

We have developed an extended source optical coherence tomography (SEES-OCT) technique in an attempt to improve signal strength for ophthalmic imaging. A line illumination with a visual angle of 7.9 mrad is produced by introducing a dispersive element in the infinity space of the sample arm. The maximum permissible exposure (MPE) of such an extended source is 3.1 times larger than that of a "standard" point source OCT, which corresponds to sensitivity improvement of 5 dB. The advantage of SEES-OCT in providing superior penetration depth over a point source system is demonstrated using swine eye tissues ex vivo. PMID:25503001

Liu, Xinyu; Yu, Xiaojun; Tang, Hongying; Cui, Dongyao; Beotra, Meghna R; Girard, Michael J A; Sun, Ding; Gu, Jun; Liu, Linbo

2014-12-15

42

Phase-Conjugate Optical Coherence Tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Quantum optical coherence tomography (Q-OCT) offers a factor-of-two improvement in axial resolution and the advantage of even-order dispersion cancellation when it is compared to conventional OCT (C-OCT). These features have been ascribed to the non-classical nature of the biphoton state employed in the former, as opposed to the classical state used in the latter. Phase-conjugate OCT (PC-OCT), introduced here, shows that non-classical light is not necessary to reap Q-OCT's a...

Erkmen, Baris I.; Shapiro, Jeffrey H.

2009-01-01

43

Adaptive optics optical coherence tomography for in vivo retinal imaging  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Optical coherence tomography (OCT) is a non-invasive micrometer-resolution volumetric imaging modality that has been employed in diverse applications. In this thesis, we first describe a GPU accelerated program to perform FDOCT data processing and real time 3D volumetric rendering. The real time visualization of volumetric images provided by the GPU acceleration was essential to the rest of the work described in this thesis. Small animal models of retinal diseases serve as a vital component...

Jian, Yifan

2014-01-01

44

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

2006-01-05

45

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

Energy Technology Data Exchange (ETDEWEB)

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.

Everett, M. J., LLNL

1998-06-02

46

Adaptive optics optical coherence tomography at 1 MHz  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Image acquisition speed of optical coherence tomography (OCT) remains a fundamental barrier that limits its scientific and clinical utility. Here we demonstrate a novel multi-camera adaptive optics (AO-)OCT system for ophthalmologic use that operates at 1 million A-lines/s at a wavelength of 790 nm with 5.3 ?m axial resolution in retinal tissue. Central to the spectral-domain design is a novel detection channel based on four high-speed spectrometers that receive light sequentially from a 1 ?...

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

2014-01-01

47

Optical coherence tomography - principles and applications  

International Nuclear Information System (INIS)

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

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Blood optical clearing studied by optical coherence tomography.  

Science.gov (United States)

The main limitation of optical imaging techniques for studying biological tissues is light scattering leading to decreasing of transmittance, which lowers the imaging quality. In this case, an immersion method for optical clearing of biological tissues can provide a possible solution to this problem, because the application of biocompatible clearing agents can reduce light scattering. Optical clearing represents a promising approach to increasing the imaging depth for various techniques, for example, various spectroscopy and fluorescent methods, and optical coherence tomography (OCT). We investigate the improvement of light penetration depth in blood after application of polyethylene glycol, polypropylene glycol, propylene glycol, and hemoglobin solutions using an OCT system. Influence of clearing agents on light transport in tissues and blood was also investigated in the mouse tail vein. PMID:23389683

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

2013-02-01

49

Primary pterygium: interpretation using optical coherence tomography  

Directory of Open Access Journals (Sweden)

Full Text Available ABSTRACT Purpose. To give a characteristic of a primary pterygium at its different stages for specification of indications to a surgical treatment using the optical coherence tomography (OCT. Material and methods. There were examined 45 eyes with primary pterygium, 53 eyes with nasal pinguecula. As a comparison group 30 eyes without signs of a pinguecula or a pterygium were investigated. Biomicroscopy with a photo-registration and the anterior segment ?C? were applied in all eyes. Results. The OCT in eyes with pterygium and pinguecula demonstrated disturbances of a normal anatomic structure of a nasal part of cornea, limbus and conjunctiva. Considerable OCT differences between a stationary and a progressive pterygium were revealed. Signs of transition of a pinguecula to a primary pterygium, invisible in the biomicroscopy, were detected by the OCT method. Conclusions. The anterior segment optical coherence tomography is a valuable source of the information in the diagnosis of pterygium. It allows to reveal subclinical signs of transition of a pinguecula to a pterygium. It is expedient to use the OCT data in a definition of indications to surgical treatment of pterygium and pinguecula.

A.V. Petrayevsky

2013-03-01

50

Doppler optical coherence tomography in cardiovascular applications  

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

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

2010-06-01

51

Doppler optical coherence tomography in cardiovascular physiology  

Science.gov (United States)

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

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

2008-09-01

52

Characterisation of optically cleared paper by optical coherence tomography  

International Nuclear Information System (INIS)

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)

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Introduction: Advances in Optical Coherence Tomography, Photoacoustic Imaging, and Microscopy  

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The editors introduce the Biomedical Optics Express feature issue, “Advances in Optical Coherence Tomography, Photoacoustic Imaging, and Microscopy,” which combines three technical areas from the 2010 Optical Society of America (OSA), Biomedical Optics (BIOMED) Topical Meeting held on 11–14 April in Miami, Florida, and includes contributions from conference attendees.

Li, X.; Beard, P. C.; Georgakoudi, I.

2010-01-01

54

Three-Dimensional Optical Coherence Tomography  

Science.gov (United States)

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

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

2009-01-01

55

Frequency domain optical tomography in human tissue  

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In this paper, a reconstruction algorithm for frequency-domain optical tomography in human tissue is presented. A fast and efficient multigrid finite difference (MGFD) method is adopted as a forward solver to obtain the simulated detector responses and the required imaging operator. The solutions obtained form MGFD method for 3D problems with weakly discontinuous cocoefficients are compared with analyzed solutions to determine the accuracy of the numerical method. Simultaneous reconstruction of both absorption and scattering coefficients for tissue-like media is accomplished by solving a perturbation equation using the Born approximation. This solution is obtained by a conjugate gradient descent method with Tikhonov regularization. Two examples are given to show the quality of the reconstruction results. Both involve the examination of anatomically accurate optical models of tissue derived from segmented 3D magnetic resonance images to which have been assigned optical coefficients to the designated tissue types. One is a map of a female breast containing two small 'added pathologies', such as tumors. The other is a map of the brain containing a 'local bleeding' area, representing a hemorrhage. The reconstruction results show that the algorithm is computationally practical and can yield qualitatively correct geometry of the objects embedded in the simulated human tissue. Acceptable results are obtaiend even when 10% noise is present in the data.

Yao, Yuqi; Wang, Yao; Pei, Yaling; Zhu, Wenwu; Hu, Jenhun; Barbour, Randall L.

1995-10-01

56

Diffuse Optical Tomography for Brain Imaging: Theory  

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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.

Yuan, Zhen; Jiang, Huabei

57

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

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

Eugen Osiac, Adrian Sa?ftoiu

2011-01-01

58

Phase-conjugate optical coherence tomography  

International Nuclear Information System (INIS)

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

59

Optical coherence tomography imaging of cardiac trabeculae.  

Science.gov (United States)

An integrated instrument is being developed to study live cardiac trabeculae, which is capable of stimulating the muscle under controlled conditions while measuring the heat production, force, and sarcomere length distribution. To improve the accuracy of estimation of stress, strain, and volumetric heat production, the geometry of the muscle must be known. A spectral domain optical coherence tomography system (SD-OCT) has been constructed and calibrated to image the trabecula mounted inside the instrument. This system was mounted above the muscle chamber and a series of equally-spaced cross-sectional images were obtained. These were processed using a workflow developed to extract cross-sectional area and volume. The initial results have demonstrated the feasibility of using OCT to capture the overall geometry of cardiac trabecula mounted in the instrument. Further work will be directed to improve the image quality for larger samples and apply meshing algorithms to the acquired data. PMID:25569927

Cheuk, Ming L; Lippok, Norman; Dixon, Alexander W; Ruddy, Bryan P; Vanholsbeeck, Frederique; Nielsen, Poul M F; Taberner, Andrew J

2014-08-01

60

Optical Coherence Tomography for Tracking Canvas Deformation  

International Nuclear Information System (INIS)

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

 
 
 
 
61

Advanced modelling of optical coherence tomography systems  

International Nuclear Information System (INIS)

Analytical and numerical models for describing and understanding the light propagation in samples imaged by optical coherence tomography (OCT) systems are presented. An analytical model for calculating the OCT signal based on the extended Huygens-Fresnel principle valid both for the single and multiple scattering regimes is reviewed. An advanced Monte Carlo model for calculating the OCT signal is also reviewed, and the validity of this model is shown through a mathematical proof based on the extended Huygens-Fresnel principle. Moreover, for the first time the model is verified experimentally. From the analytical model, an algorithm for enhancing OCT images is developed; the so-called true-reflection algorithm in which the OCT signal may be corrected for the attenuation caused by scattering. For the first time, the algorithm is demonstrated by using the Monte Carlo model as a numerical tissue phantom. Such algorithm holds promise for improving OCT imagery and to extend the possibility for functional imaging

62

Varnish Ablation Control by Optical Coherence Tomography  

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Preliminary results of the application of optical coherence tomography (OCT), in particular in its spectral mode (SOCT) to the control of a varnish ablation process, are presented. Examination of the ablation craters made with an Er:YAG laser allows optimization of the laser emission parameters controlling fluence with respect to efficiency and safety of the ablation process. Results of measurements of ablation crater depth as a function of the number of pulses for a given fluence are presented for selected resins. This validates the applicability of SOCT to calibration of ablation conditions for the particular laser-varnish-paint layer combinations, and of its usage in planning the varnish ablation procedure. These results also imply that a review of conventional ablation thresholds is called for. Applicability of the SOCT technique to contemporaneous in situ monitoring of the range of varnish ablation is discussed.

63

Fused Entropy Algorithm in Optical Computed Tomography  

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Full Text Available In most applications of optical computed tomography (OpCT, limited-view problems are often encountered, which can be solved to a certain extent with typical OpCT reconstructive algorithms. The concept of entropy first emerged in information theory has been introduced into OpCT algorithms, such as maximum entropy (ME algorithms and cross entropy (CE algorithms, which have demonstrated their superiority over traditional OpCT algorithms, yet have their own limitations. A fused entropy (FE algorithm, which follows an optimized criterion combining self-adaptively ME with CE, is proposed and investigated by comparisons with ME, CE and some traditional OpCT algorithms. Reconstructed results of several physical models show this FE algorithm has a good convergence and can achieve better precision than other algorithms, which verifies the feasibility of FE as an approach of optimizing computation, not only for OpCT, but also for other image processing applications.

Xiong Wan

2014-02-01

64

Computed tomography in orbital fractures and optic nerve trauma  

International Nuclear Information System (INIS)

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

65

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

Science.gov (United States)

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

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

2012-03-01

66

Photoacoustic tomography: Ultrasonically beating optical diffusion and diffraction  

Science.gov (United States)

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

Wang, Lihong

2014-03-01

67

Mid-infrared optical coherence tomography.  

Science.gov (United States)

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

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

2007-12-01

68

Optical coherence tomography of the eye  

Science.gov (United States)

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

Hee, Michael Richard

1997-10-01

69

Optical coherence tomography imaging in uveitis.  

Science.gov (United States)

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

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

2014-04-01

70

Full 3D displacement field measurement by Optical Scanning Tomography and PIV Tomography  

Directory of Open Access Journals (Sweden)

Full Text Available This work is about the development of new techniques for the measurement of the three components of the velocity inside a volume. A comparison of two techniques, optical scanning tomography and algebraic reconstruction tomography method, is performed with 3D displacement tests of transparent solid blocks.

Tremblais B.

2010-06-01

71

Mapping distributed brain function and networks with diffuse optical tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Mapping of human brain function has revolutionized systems neuroscience. However, traditional functional neuroimaging by positron emission tomography or functional magnetic resonance imaging cannot be used when applications require portability, or are contraindicated because of ionizing radiation (positron emission tomography) or implanted metal (functional magnetic resonance imaging). Optical neuroimaging offers a non-invasive alternative that is radiation free and compatible with implanted ...

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

2014-01-01

72

Computed tomography of sarcoidosis of the optic nerve  

International Nuclear Information System (INIS)

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

73

Ultrahigh-resolution optical coherence tomography of canthaxanthine retinal crystals.  

Science.gov (United States)

A case of crystalline retinopathy caused by prolonged ingestion of an oral tanning agent containing canthaxanthine is described. Color fundus photography and ultrahigh-resolution optical coherence tomography were performed. PMID:16583635

Chan, Annie; Ko, Tony H; Duker, Jay S

2006-01-01

74

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

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

2008-01-01

75

Motion contrast using optical coherence tomography  

Science.gov (United States)

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.

Fingler, Jeffrey Paul

76

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

Directory of Open Access Journals (Sweden)

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

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

2011-01-01

77

Polarization sensitive optical coherence tomography detection method  

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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.

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

1999-05-12

78

Optical coherence tomography for quantitative surface topography.  

Science.gov (United States)

We address the measurement and correction of fan distortion in optical coherence tomography (OCT). This effect arises from the scanning system configuration and prevents one, in general, from obtaining quantitative topographic data from OCT. Computer simulations allowed us to quantify the effect and evaluate its dependence on the scanning mirror separation and design of the collimating lens, as well as to estimate the optimal axial position of that lens to minimize the fan distortion. We also developed a numerical algorithm based on 3-D ray propagation for the correction of the residual fan distortion. The effect was studied experimentally using a custom developed time-domain OCT in a Michelson configuration provided with a confocal channel, and the accuracy of the fan distortion correction algorithm tested on samples of known dimensions (flat surfaces and spherical lenses). With a proper calibration of the system with use of an onfocal channel, this algorithm makes it possible for time-domain OCT devices to be used as topographers. PMID:20011011

Ortiz, Sergio; Siedlecki, Damian; Remon, Laura; Marcos, Susana

2009-12-10

79

Polarization sensitive optical coherence tomography detection method  

International Nuclear Information System (INIS)

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

80

Multiplicative optical tomography of cardiac electrical activity  

International Nuclear Information System (INIS)

Cardiac electrical activity can be mapped today through the response of voltage-sensitive dyes; but poor transparency of muscle tissue has enforced shallow-depth imaging. We present a three-dimensional (3D) reconstruction method for electrical activity deep inside the myocardial wall. Our approach is nonlinear and differs substantially from standard diffusive optical tomography. It does not require matrix inversion, data regularization or a priori information concerning the original object. Opposite sides of a slab-shaped preparation are scanned in parallel by detection and illumination points with a constant vector offset between illumination and detection axes (biaxial scanning). Scanning is performed in two perpendicular directions. In each direction, a pair of 2D images is obtained under offsets of opposite signs. These two pairs are the input for a multiplicative reconstruction algorithm, whose output is a 3D image. The overall procedure was successfully tested on computer-generated sources that include points, lines and hemispheres, patterned after actual electrophysiological excitations. The algorithm is computationally efficient and stable with respect to varying noise levels in the raw data

 
 
 
 
81

Attenuation compensation for optical coherence tomography imaging  

Science.gov (United States)

Optical coherence tomography (OCT) is a noninvasive technique that provides micrometer-scale imaging of tissue. As most biological tissues are considered turbid, it causes attenuation of the OCT signal and limits the depth penetration. Although a few algorithms had been developed to compensate the attenuation, almost all of them need to extract the scattering parameters before doing the compensation procedure. Because the real biological samples are anisotropic and multilayer-like structure, it is not time-efficient to model and solve these scattering parameters. This paper introduces a new method to compensate the OCT signal attenuation in depth. By analyzing the input signal, a compensation function is adaptively derived for each A-scan line, which can be used effectively to compensate the energy loss in the large sections and enhance the details in the deep, dark-like areas. Three bio-samples, a piece of onion, a Poecilia Wingei fish and a piece of rabbit abdominal aorta, were used to test our method. OCT images obtained by a swept-source OCT system were processed by the proposed method. Results show the visualization of structures in OCT images has been evidently improved, especially in deep region.

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

2009-12-01

82

Adaptive optics optical coherence tomography at 1 MHz.  

Science.gov (United States)

Image acquisition speed of optical coherence tomography (OCT) remains a fundamental barrier that limits its scientific and clinical utility. Here we demonstrate a novel multi-camera adaptive optics (AO-)OCT system for ophthalmologic use that operates at 1 million A-lines/s at a wavelength of 790 nm with 5.3 ?m axial resolution in retinal tissue. Central to the spectral-domain design is a novel detection channel based on four high-speed spectrometers that receive light sequentially from a 1 × 4 optical switch assembly. Absence of moving parts enables ultra-fast (50ns) and precise switching with low insertion loss (-0.18 dB per channel). This manner of control makes use of all available light in the detection channel and avoids camera dead-time, both critical for imaging at high speeds. Additional benefit in signal-to-noise accrues from the larger numerical aperture afforded by the use of AO and yields retinal images of comparable dynamic range to that of clinical OCT. We validated system performance by a series of experiments that included imaging in both model and human eyes. We demonstrated the performance of our MHz AO-OCT system to capture detailed images of individual retinal nerve fiber bundles and cone photoreceptors. This is the fastest ophthalmic OCT system we know of in the 700 to 915 nm spectral band. PMID:25574431

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

2014-12-01

83

Imaging Retinal Capillaries Using Ultrahigh-Resolution Optical Coherence Tomography and Adaptive Optics  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Ultrahigh-resolution optical coherence tomography with adaptive optics provides micrometer-scale 3D resolution that is attractive for imaging the retinal microvasculature. The potential for detecting retinal capillaries in healthy subjects using this methodology is investigated.

Wang, Qiang; Kocaoglu, Omer P.; Cense, Barry; Bruestle, Jeremy; Jonnal, Ravi S.; Gao, Weihua; Miller, Donald T.

2011-01-01

84

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

Absorption and emission optical projection tomography (OPT), alternatively referred to as optical computed tomography (optical-CT) and optical-emission computed tomography (optical-ECT), are recently developed three-dimensional imaging techniques with value for developmental biology and ex vivo gene expression studies. The techniques' principles are similar to the ones used for x-ray computed tomography and are based on the approximation of negligible light scattering in optically cleared sam...

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

2010-01-01

85

Optical Coherence Tomography for Brain Imaging  

Science.gov (United States)

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

Liu, Gangjun; Chen, Zhongping

86

Adaptive optics optical coherence tomography with dynamic retinal tracking.  

Science.gov (United States)

Adaptive optics optical coherence tomography (AO-OCT) is a highly sensitive and noninvasive method for three dimensional imaging of the microscopic retina. Like all in vivo retinal imaging techniques, however, it suffers the effects of involuntary eye movements that occur even under normal fixation. In this study we investigated dynamic retinal tracking to measure and correct eye motion at KHz rates for AO-OCT imaging. A customized retina tracking module was integrated into the sample arm of the 2nd-generation Indiana AO-OCT system and images were acquired on three subjects. Analyses were developed based on temporal amplitude and spatial power spectra in conjunction with strip-wise registration to independently measure AO-OCT tracking performance. After optimization of the tracker parameters, the system was found to correct eye movements up to 100 Hz and reduce residual motion to 10 µm root mean square. Between session precision was 33 µm. Performance was limited by tracker-generated noise at high temporal frequencies. PMID:25071963

Kocaoglu, Omer P; Ferguson, R Daniel; Jonnal, Ravi S; Liu, Zhuolin; Wang, Qiang; Hammer, Daniel X; Miller, Donald T

2014-07-01

87

A comprehensive method for optical-emission computed tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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/P...

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

2010-01-01

88

Atherosclerosis diagnostic imaging by optical spectroscopy and optical coherence tomography  

Science.gov (United States)

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

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

2006-02-01

89

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

Science.gov (United States)

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.

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

2014-03-01

90

Optical coherence tomography of the prostate nerves  

Science.gov (United States)

Preservation of the cavernous nerves during prostate cancer surgery is critical in preserving a man's ability to have spontaneous erections following surgery. These microscopic nerves course along the surface of the prostate within a few millimeters of the prostate capsule, and they vary in size and location from one patient to another, making preservation of the nerves difficult during dissection and removal of a cancerous prostate gland. These observations may explain in part the wide variability in reported sexual potency rates (9--86%) following prostate cancer surgery. Any technology capable of providing improved identification, imaging, and visualization of the cavernous nerves during prostate cancer surgery would be of great assistance in improving sexual function after surgery, and result in direct patient benefit. Optical coherence tomography (OCT) is a noninvasive optical imaging technique capable of performing high-resolution cross-sectional in vivo and in situ imaging of microstructures in biological tissues. OCT imaging of the cavernous nerves in the rat and human prostate has recently been demonstrated. However, improvements in the OCT system and the quality of the images for identification of the cavernous nerves is necessary before clinical use. The following chapters describe complementary approaches to improving identification and imaging of the cavernous nerves during OCT of the prostate gland. After the introduction to OCT imaging of the prostate gland, the optimal wavelength for deep imaging of the prostate is studied in Chapter 2. An oblique-incidence single point measurement technique using a normal-detector scanning system was implemented to determine the absorption and reduced scattering coefficients, mua and m's , of fresh canine prostate tissue, ex vivo, from the diffuse reflectance profile of near-IR light as a function of source-detector distance. The effective attenuation coefficient, mueff, and the Optical Penetration Depth (OPD) were then calculated for near-IR wavelengths of 1064 nm, 1307 nm, and 1555 nm. Chapters 3 and 4 describe locally adaptive denoising algorithms applied to reduce speckle noise in OCT images of the prostate taken by experimental and clinical systems, respectively. The dual-tree complex wavelet transform (CDWT) is a relatively recent enhancement to the discrete wavelet transform (DWT), with important additional properties: It is nearly shift invariant and directionally selective in two and higher dimensions. The CDWT algorithm was implemented for denoising of OCT images. In Chapter 5, 2-D OCT images of the rat prostate were segmented to differentiate the cavernous nerves from the prostate gland. To detect these nerves, three image features were employed: Gabor filter, Daubechies wavelet, and Laws filter. The Gabor feature was applied with different standard deviations in the x and y directions. In the Daubechies wavelet feature, an 8-tap Daubechies orthonormal wavelet was implemented, and the low pass sub-band was chosen as the filtered image. Finally, Laws feature extraction was applied to the images. The features were segmented using a nearest-neighbor classifier. Morphological post-processing was used to remove small voids. In Chapter 6, a new algorithm based on thresholding and first-order derivative class of differential edge detection was implemented to see deeper in the OCT images. One of the main limitations in OCT imaging of the prostate tissue is the inability to image deep into opaque tissues. Currently, OCT is limited to an image depth of approximately 1 min in opaque tissues. Theoretical comparisons of detection performance for Fourier domain (FD) and time domain (TD) OCT have been previously reported. In Chapter 7, we compare several image quality metrics including signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and equivalent number of looks (ENL) for TD-OCT and FD-OCT images taken of the rat prostate, in vivo. The results show that TD-OCT has inferior CNR, but superior SNR compared to FD-OCT, and that TD-OCT is better for deep imaging of op

Chitchian, Shahab

91

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2012-01-01

92

Imaging myocardial fiber orientation using polarization sensitive optical coherence tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Knowledge of myocardial fiber architecture is essential towards understanding heart functions. We demonstrated in this study a method to map cardiac muscle structure using the local optical axis obtained from polarization-sensitive optical coherence tomography (PSOCT). An algorithm was developed to extract the true local depth-resolved optical axis, retardance, and diattenuation from conventional round-trip results obtained in a Jones matrix-based PSOCT system. This method was applied to imag...

Fan, Chuanmao; Yao, Gang

2013-01-01

93

Polarization-sensitive quantum-optical coherence tomography  

International Nuclear Information System (INIS)

We set forth a polarization-sensitive quantum-optical coherence tomography (PS-QOCT) technique that provides axial optical sectioning with polarization-sensitive capabilities. The technique provides a means for determining information about the optical path length between isotropic reflecting surfaces, the relative magnitude of the reflectance from each interface, the birefringence of the interstitial material, and the orientation of the optical axis of the sample. PS-QOCT is immune to sample dispersion and therefore permits measurements to be made at depths greater than those accessible via ordinary optical coherence tomography. We also provide a general Jones matrix theory for analyzing PS-QOCT systems and outline an experimental procedure for carrying out such measurements

94

Optical Doppler tomography based on a field programmable gate array  

DEFF Research Database (Denmark)

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.

Larsen, Henning Engelbrecht; Nilsson, Ronnie Thorup

2008-01-01

95

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

To overcome the intensive light scattering in biological tissue, diffuse optical tomography (DOT) in the near-infrared range for breast lesion detection is usually combined with other imaging modalities, such as ultrasound, x-ray, and magnetic resonance imaging, to provide guidance. However, these guiding imaging modalities may depend on different contrast mechanisms compared to the optical contrast in the DOT. As a result, they cannot provide reliable guidance for DOT because some lesions ma...

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

2013-01-01

96

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

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

2010-01-01

97

Optic disc topography of normal Indian eyes: An assessment using optical coherence tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Purpose: To study the optic disc topographic measurements of normal Indian eyes using optical coherence tomography (OCT). Materials and Methods: One hundred and fifty eyes selected randomly from 150 normal Indian subjects of both sex and various age groups underwent optic disc imaging with the OCT using the fast optic disc protocol. Results: Mean ± standard deviation of the optic disc topographic measurements were: disc area 2.63 ± 0.55 mm 2 ...

Dacosta Shaun; Bilal Sheena; Rajendran Babu; Janakiraman P

2008-01-01

98

Time-resolved diffuse optical tomography in neurosciences.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Diffuse optical tomography is a new modality of functional medical imaging. Its application to the study of brain activity is very promising. In this context, this work deals with understanding light propagation through the head thanks to simulations based on the diffusion equation which is solved by the finite element method on models obtained by the segmentation of MRI. These simulations show the weak penetration of light in the brain because of the particular optical properties of the head...

Montcel, Bruno

2005-01-01

99

The Role of Optical Coherence Tomography in Coronary Intervention  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Optical coherence tomography (OCT) is an optical analog of intravascular ultrasound (IVUS) that can be used to examine the coronary arteries and has 10-fold higher resolution than IVUS. Based on polarization properties, OCT can differentiate tissue characteristics (fibrous, calcified, or lipid-rich plaque) and identify thin-cap fibroatheroma. Because of the strong attenuation of light by blood, OCT systems required the removal of blood during OCT examinations. A recently developed frequency-d...

Terashima, Mitsuyasu; Kaneda, Hideaki; Suzuki, Takahiko

2012-01-01

100

Structural validation of oral mucosal tissue using optical coherence tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Background: Optical coherence tomography (OCT) is a non-invasive optical technology using near-infrared light to produce cross-sectional tissue images with lateral resolution. Objectives: The overall aims of this study was to generate a bank of normative and pathological OCT data of the oral tissues to allow identification of cellular structures of normal and pathological processes with the aim to create a diagnostic algorithm which can be used in the early detection of oral disorde...

Hamdoon, Z.; Jerjes, W.; Al-delayme, R.; Mckenzie, G.; Jay, A.; Hopper, C.

2012-01-01

 
 
 
 
101

High speed full range complex spectral domain optical coherence tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present a high speed full range spectral domain optical coherence tomography system. By inserting a phase modulator into the reference arm and recording of every other spectrum with a 90° phase shift (introduced by the phase modulator) we are able to distinguish between negative and positive optical path differences with respect to the reference mirror. A modified two-frame algorithm eliminates the problem of suppressing symmetric structure terms in the final image. To demonstrate the per...

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

2005-01-01

102

Noninvasive evaluation of retinal leakage using optical coherence tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Bernardes, Rui; Santos, Torcato; Serranho, Pedro; Lobo, Conceic?a?o; Cunha-vaz, Jose?

2011-01-01

103

Optical coherence tomography changes in macular CMV retinitis  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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).

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

2012-01-01

104

RADIAL COMPUTED TOMOGRAPHY OF AIR CONTAMINANTS USING OPTICAL REMOTE SENSING  

Science.gov (United States)

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

105

Normalized Born ratio for fluorescence optical projection tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present a normalized Born approach for fluorescence optical projection tomography that takes into account tissue absorption properties. This approach can be particularly useful to study fluorochrome distribution within tissue. We use the algorithm to three-dimensionally reconstruct and characterize a fluorescein isothiocyanate containing absorptive phantom and an infarcted mouse heart previously injected with a fluorescent molecular probe.

Vinegoni, Claudio; Razansky, Daniel; Figueiredo, Jose-luiz; Nahrendorf, Matthias; Ntziachristos, Vasilis; Weissleder, Ralph

2009-01-01

106

Optical coherence tomography to monitor photodynamic therapy in pathological myopia  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

2006-01-01

107

Imaging of Breast Cancer and Epilepsy using Diffuse Optical Tomography  

Science.gov (United States)

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

Jiang, Huabei

2009-11-01

108

Imaging of dental implant osseointegration using optical coherent tomography  

Science.gov (United States)

Investigation of initial implant stability with different dental implant designs is an important task to obtain good quality dental implants. Failure of a dental implant is often related to failure to osseointegrate correctly. Optical Coherent Tomography is a competitive non-invasive method of osseointegration investigation. FD-OCT with Swept Source was used to obtain 3-D image of the peri-implant tissue (soft and hard) in the case of mandible fixed screw. 1350 nm centered laser source give better images than 850 nm laser source for hard tissue imaging. Present work suggests that Optical Coherent Tomography is a proper technique to obtain the image of the contact tissue-metal screw. OCT images are useful to evaluate optical properties of bone tissues.

Ionita, I.; Reisen, P.

2009-02-01

109

Application of optical longitudinal tomography for dental introscopy  

Science.gov (United States)

A new method of dental introscopy in-vitro is suggested by the authors. This method implies the usage of longitudinal tomography techniques and is characterized by non-invasive and non-harmful diagnostics features, as well as interactive regime of image reconstruction which lets an operator (doctor) to control the diagnostics process in real time. He-Ne laser emission is used for obtaining of the projections. By the means of longitudinal tomography, images of different sections of an object (tooth) can be reconstructed. An experiment was held by the authors in which 100 projections of a tooth (premolar) were obtained and images of 10 different sections were reconstructed. These images were later compared to real sections of the tooth. This experiment proved that optical longitudinal tomography can be successfully used for dental introscopy. Authors claim that optical tomographic methods can be used for diagnostics of other biological objects as well. Such objects are characterized by spatial geometrical anisotropy (tubular bones, phalanxes of fingers, penis, etc.). It is especially promising to use this method for children's dentistry. the authors discuss some features of the data acquisition system for optical longitudinal tomography. Reconstruction algorithms are described. The results of experimental reconstruction are presented and advantages of this diagnostics method are discussed.

Levin, Gennady G.; Burgansky, Alexander A.; Levandovski, Alexei G.

1997-08-01

110

Integrated intravascular optical coherence tomography ultrasound imaging system  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We report on a dual-modality optical coherence tomography (OCT) ultrasound (US) system for intravascular imaging. To the best of our knowledge, we have developed the first integrated OCT-US probe that combines OCT optical components with an US transducer. The OCT optical components mainly consist of a single-mode fiber, a gradient index lens for light-beam focusing, and a right-angled prism for reflecting light into biological tissue. A 40-MHz piezoelectric transducer (PZT-5H) side-viewing US...

Yin, Jiechen; Yang, Hao-chung; Li, Xiang; Zhang, Jun; Zhou, Qifa; Hu, Changhong; Shung, K. Kirk; Chen, Zhongping

2010-01-01

111

Polarization-Sensitive Quantum Optical Coherence Tomography: Experiment  

CERN Document Server

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.

Booth, Mark C; Teich, Malvin Carl

2010-01-01

112

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

Science.gov (United States)

The authors report fundus autofluorescence (FAF) and spectral-domain optical coherence tomography (OCT) findings of two consecutive patients who presented with optic disk melanocytoma (ODM). A retrospective study was performed by reviewing medical records and ophthalmic imaging examinations. Optical coherence tomography findings were sloped and brightly reflective anterior tumor surface, adjacent retinal desorganization and abrupt posterior optical shadowing. Vitreous seeds were found in one patient. Fundus autofluorescence revealed outstanding hypoautofluorescence at the tumor area and isoautofluorescence at the remaining retina. Optical coherence tomography findings of the reported cases are consistent with those reported in the reviewed literature. Fundus autofluorescence has been used in the assessment of choroidal melanocytic tumors, but not yet in melanocytomas. We assume that this is the first report of these findings and believe that when its pattern has become clearly defined, fundus autofluorescence will be a useful tool to avoid misdiagnosis in suspicious cases and for follow-up. PMID:25627191

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

2014-12-01

113

Design and characterization of SiON integrated optics components for optical coherence tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Optical coherence tomography (OCT) is a technique for high resolution imaging of biological tissues with a depth range of a few millimeters. OCT is based on interferometry to enable depth ranging. Currently, optical components for OCT are rather bulky and expensive; the use of integrated optical circuits presents a great opportunity to reduce costs and enhance system functionality and performance. We present the design and characterization of SiON-based integrated optics waveguides, splitters...

Nguyen, V. Duc; Kalkman, J.; Ismail, N.; Sun, F.; Wo?rhoff, K.; Driessen, A.; Pollnau, M.; Leeuwen, T. G.

2009-01-01

114

In vivo detection of cortical optical changes associated with seizure activity with optical coherence tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The most common technology for seizure detection is with electroencephalography (EEG), which has low spatial resolution and minimal depth discrimination. Optical techniques using near-infrared (NIR) light have been used to improve upon EEG technology and previous research has suggested that optical changes, specifically changes in near-infrared optical scattering, may precede EEG seizure onset in in vivo models. Optical coherence tomography (OCT) is a high resolution, minimally invasive imagi...

Eberle, Melissa M.; Reynolds, Carissa L.; Szu, Jenny I.; Wang, Yan; Hansen, Anne M.; Hsu, Mike S.; Islam, M. Shahidul; Binder, Devin K.; Park, B. Hyle

2012-01-01

115

Wavelength-encoded tomography based on optical temporal Fourier transform  

Science.gov (United States)

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

Zhang, Chi; Wong, Kenneth K. Y.

2014-09-01

116

Quantum-optical coherence tomography with dispersion cancellation  

International Nuclear Information System (INIS)

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

117

Optical coherence tomography guided peeling of macular epiretinal membrane  

Directory of Open Access Journals (Sweden)

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

Yoshio Hirano

2010-12-01

118

Positron emission tomography and optical tissue imaging  

Science.gov (United States)

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

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

2012-05-22

119

Anatomical Atlas-Guided Diffuse Optical Tomography of Brain Activation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

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

2010-01-01

120

Three Dimensional Optical Coherence Tomography Imaging: Advantages and Advances  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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, ...

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

2010-01-01

 
 
 
 
121

Multiple and dependent scattering effects in Doppler optical coherence tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Kalkman, J.; Bykov, A. V.; Faber, D. J.; Leeuwen, T. G.

2010-01-01

122

Imaging tamoxifen retinopathy using spectral-domain optical coherence tomography  

Directory of Open Access Journals (Sweden)

Full Text Available A case of tamoxifen retinopathy examined with spectral-domain optical coherence tomography (SD-OCT is presented. The typical refractile deposits are located between ganglion cell layer and inner plexiform layer in SD-OCT. A defect on the outer retinal layer with disruption of the photoreceptor layer with sharp edges is seen. The still attached posterior hyaloids gives evidence of other pathomechanism involved in the outer retinal defect than that of macular hole, as suggested in the literature.

Caramoy, Albert

2011-01-01

123

Revealing retroperitoneal liposarcoma morphology using optical coherence tomography  

Science.gov (United States)

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

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

2011-02-01

124

Optical coherence tomography guided peeling of macular epiretinal membrane  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Yoshio Hirano, Tsutomu Yasukawa, Yuichiro OguraDepartment of Ophthalmology and Visual Science, Nagoya City University Graduate School of Medical Sciences, Nagoya, JapanAbstract: Optical coherence tomography (OCT) has emerged as a powerful diagnostic aid in disorders of the vitreoretinal juncture. The purpose of this study is to determine whether OCT can be used as an additional tool for evaluating an architecture including the thickened area, and the identifiable edge of a macular epiretinal ...

Yoshio Hirano; Tsutomu Yasukawa; Yuichiro Ogura

2010-01-01

125

Imaging Natural Occlusal Caries Lesions with Optical Coherence Tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 acq...

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

2010-01-01

126

Optical coherence tomography classification of diabetic cystoid macular edema  

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Yasser M Helmy, Heba R Atta AllahDepartment of Ophthalmology, Minia University, Minya, EgyptPurpose: To propose a new classification of diabetic cystoid macular edema (CME) based on optical coherence tomography (OCT) findings and cover all new important findings.Patients and methods: A retrospective study was carried out in the El-Minia Investigation Eye Center between January 2012 and November 2012. It included 104 eyes of 86 patients, aged between 50 and 71 years, all with type II diabetes ...

Ym, Helmy; Hr, Atta Allah

2013-01-01

127

"Quantum-optical coherence tomography" with classical light  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Lavoie, Jonathan; Kaltenbaek, Rainer; Resch, Kevin J.

2009-01-01

128

Corneal topography from spectral optical coherence tomography (sOCT)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2011-01-01

129

Phase-locked Fourier domain optical coherence tomography  

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Fourier or spectral domain optical coherence tomography (FDOCT) is a multi-dimensional interferometric imaging modality that has attracted increasing interest during the last few years. The reason is its outstanding sensitivity allowing high speed 2D and 3D imaging of weakly backscattering biological tissues in vivo and with high axial resolution. FDOCT has today largely replaced the preceding time domain OCT due to its marked advantage in sensitivity and acquisition speed. In particular, for...

Bachmann, Adrian H.

2008-01-01

130

An Active Retinal Tracker for Clinical Optical Coherence Tomography Systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

An active, hardware-based retinal tracker was built into a clinical optical coherence tomography (OCT) system for stabilization of high-resolution retinal sections. The retinal tracker locks onto common fundus features, detects transverse eye motion via changes in feature reflectance, and positions the OCT diagnostic beam to fixed coordinates on the retina with mirrors driven by a feedback control loop. The system was tested in a full clinical protocol on subjects with normal and glaucomatous...

Hammer, Daniel X.; Ferguson, R. Daniel; Paunescu, Lelia Adelina; Beaton, Siobahn; Schuman, Joel S.

2005-01-01

131

Wide-field optical coherence tomography: imaging of biological tissues  

Science.gov (United States)

We describe a two-dimensional optical coherence tomography technique with which we were able to obtain multiple longitudinal slices of a biological sample directly in a single Z scan. The system is based on a femtosecond Cr4+:forsterite laser and an infrared camera for wide-field imaging of the sample with a depth resolution of 5 mum. With this imaging apparatus we were able to investigate human skin and mouse ear samples and to observe the different constitutive tissues.

Bordenave, E.; Abraham, E.; Jonusauskas, G.; Tsurumachi, N.; Oberle, J.; Rulliere, C.; Minot, P. E.; Lassegues, M.; Bazeille, J. E. Surleve

2002-04-01

132

Handheld simultaneous scanning laser ophthalmoscopy and optical coherence tomography system  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Scanning laser ophthalmoscopy (SLO) and optical coherence tomography (OCT) are widely used retinal imaging modalities that can assist in the diagnosis of retinal pathologies. The combination of SLO and OCT provides a more comprehensive imaging system and a method to register OCT images to produce motion corrected retinal volumes. While high quality, bench-top SLO-OCT systems have been discussed in the literature and are available commercially, there are currently no handheld designs. We descr...

Larocca, Francesco; Nankivil, Derek; Farsiu, Sina; Izatt, Joseph A.

2013-01-01

133

Real-time compressive sensing spectral domain optical coherence tomography.  

Science.gov (United States)

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

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

2014-01-01

134

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

Science.gov (United States)

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.

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

2014-04-01

135

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

Science.gov (United States)

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

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

2014-04-21

136

Spectral-domain optical coherence tomography on a silicon chip  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Optical coherence tomography (OCT) is a non-invasive optical technique for high-resolution cross-sectional imaging of specimens, with many applications in clinical medicine and industry (e.g. materials testing, quality assurance, and process control). Current state-of-the-art OCT systems operate in the frequency domain, using either a broad-band light source and a spectrometer, known as ‘spectral-domain OCT’ (SD-OCT), or a rapidly tunable laser, known as ‘swept-source OCT’ (SS-OCT). B...

Akca, Bakiye Imran

2012-01-01

137

"Quantum-optical coherence tomography" with classical light  

CERN Document Server

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

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

2009-01-01

138

Jade detection and analysis based on optical coherence tomography images  

Science.gov (United States)

Optical coherence tomography is a fundamentally new type of optical sensing technology that can perform high-resolution, cross sectional sensing of the internal structure of materials and biological samples. This work briefly describes its capability of exploring and analyzing the internal structures and textures of various jades. With a depth resolution of 4 ?m in jade and penetration range of 5 mm in jade, swept-source OCT could be used as a new powerful instrument to generate 3-D volume data of jade, which is important for applications in jade industry and artwork, particularly for jade detection and classification, counterfeit recognition, and guided artistic carving.

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

2010-06-01

139

Fast image reconstruction in fluorescence optical tomography using data compression.  

Science.gov (United States)

We present a method for fast reconstruction in fluorescence optical tomography with very large data sets. In recent reports, CCD cameras at multiple positions have been used to collect optical measurements, producing more than 10(7) data samples. This makes storage of the full system Jacobian infeasible, and so data are usually subsampled. The method reported here allows use of the full data set, via image compression methods, and explicit construction of the (small) Jacobian, meaning optimal inversion methods can be applied, and thus leading to very fast reconstruction. PMID:20195345

Rudge, Timothy J; Soloviev, Vadim Y; Arridge, Simon R

2010-03-01

140

Monitoring cellular remodeling of collageneous matrix using optical coherence tomography  

Science.gov (United States)

In this paper we develop the concept of a living optical phantom that uses engineered tissue as a phantom for calibration and optimization of biomedical optics instrumentation. With this method, the effects of biological processes on measured signals can be studied in a well controlled manner. To demonstrate this concept, the effects of cellular remodeling of a collagen matrix on the optical scattering properties were investigated using optical coherence tomography (OCT). Living optical phantoms of the vascular system were created by seeding smooth muscle cells in a collagen matrix. The optical scattering properties (scattering coefficient ? s and effective anisotropy factor g eff) were extracted from OCT images through mathematical processing. We found that the scattering coefficient of a remodeled matrix was generally higher than that of an unmodified matrix. The results indicate that OCT may provide meaningful information on how cellular remodeling of an extracellular collagen matrix changes its scattering properties. More broadly, we believe that making such optical measurements on living optical phantoms can help define the potential of biomedical optics technologies for studying biological systems.

Levitz, David; Vartanian, Keri; Jacques, Steven L.

2006-08-01

 
 
 
 
141

Phase-sensitive imaging of the outer retina using optical coherence tomography and adaptive optics  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The cone photoreceptor’s outer segment (OS) experiences changes in optical path length, both in response to visible stimuli and as a matter of its daily course of renewal and shedding. These changes are of interest, to quantify function in healthy cells and assess dysfunction in diseased ones. While optical coherence tomography (OCT), combined with adaptive optics (AO), has permitted unprecedented three-dimensional resolution in the living retina, it has not generally been able to measure t...

Jonnal, Ravi S.; Kocaoglu, Omer P.; Wang, Qiang; Lee, Sangyeol; Miller, Donald T.

2011-01-01

142

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2009-01-01

143

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

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

2014-01-01

144

Optical coherence tomography as film thickness measurement technique  

Science.gov (United States)

Optical coherence tomography (OCT) is a powerful optical method, noninvasive and noncontact diagnostic method. Although it is usually used for medical examinations, particularly in ocular exploration; it can also be used in optical metrology as measure technique. In this work, we use OCT to measure thicknesses of films. In OCT, depth profiles are constructed by measuring the time delay of back reflected light by interferometry measurements. Frequency in k-space is proportional to optical path difference. Then the reflectivity profile is obtained by a Fourier transformation, and the difference between two successive peaks of the resulting spectrum gives the film thickness. Several films, food-type, of different thicknesses were investigated and the results were very accurate.

Manallah, Aissa; Bouafia, Mohamed; Meguellati, Said

2015-01-01

145

Ultrasound-modulated optical tomography at new depth  

Science.gov (United States)

Ultrasound-modulated optical tomography (UOT) has the potential to reveal optical contrast deep inside soft biological tissues at an ultrasonically determined spatial resolution. The optical imaging depth reported so far has, however, been limited, which prevents this technique from broader applications. Our latest experimental exploration has pushed UOT to an unprecedented imaging depth. We developed and optimized a UOT system employing a photorefractive crystal-based interferometer. A large aperture optical fiber bundle was used to enhance the efficiencies for diffuse light collection and photorefractive two-wave-mixing. Within the safety limits for both laser illumination and ultrasound modulation, the system has attained the ability to image through a tissue-mimicking phantom of 9.4 cm in thickness, which has never been reached previously by UOT.

Lai, Puxiang; Xu, Xiao; Wang, Lihong V.

2012-06-01

146

Improved visualization of outer retinal morphology with aberration cancelling reflective optical design for adaptive optics - optical coherence tomography.  

Science.gov (United States)

We present an aberration cancelling optical design for a reflective adaptive optics - optical coherence tomography (AO-OCT) retinal imaging system. The optical performance of this instrument is compared to our previous multimodal AO-OCT/AO-SLO retinal imaging system. The feasibility of new instrumentation for improved visualization of microscopic retinal structures is discussed. Examples of images acquired with this new AO-OCT instrument are presented. PMID:24298411

Lee, Sang-Hyuck; Werner, John S; Zawadzki, Robert J

2013-01-01

147

Improved visualization of outer retinal morphology with aberration cancelling reflective optical design for adaptive optics - optical coherence tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present an aberration cancelling optical design for a reflective adaptive optics - optical coherence tomography (AO-OCT) retinal imaging system. The optical performance of this instrument is compared to our previous multimodal AO-OCT/AO-SLO retinal imaging system. The feasibility of new instrumentation for improved visualization of microscopic retinal structures is discussed. Examples of images acquired with this new AO-OCT instrument are presented.

Lee, Sang-hyuck; Werner, John S.; Zawadzki, Robert J.

2013-01-01

148

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

International Nuclear Information System (INIS)

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

149

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

Energy Technology Data Exchange (ETDEWEB)

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

Cheng, Hsu-Chih; Liu, Yi-Cheng

2010-02-10

150

A miniature forward-imaging optical coherence tomography (OCT) probe  

Science.gov (United States)

Optical coherence tomography (OCT) has had a tremendous global health impact upon the current ability to diagnose, treat, and monitor multiple eye diseases. We propose that a miniature forward-imaging OCT probe can be developed for real-time ocular imaging. A miniature 25-gauge forward-imaging probe was designed and developed to use with an 850 nm spectral-domain optical coherence tomography (SDOCT) system (Bioptigen, Inc. Durham, NC). Imaging parameters were determined. Ocular tissues were examined with the miniature OCT probe. A miniature SDOCT probe was developed with the scanning driver within the hand piece. The SDOCT fiber-scanning probe maximally transmitted power of 800 ?W. The scanning range was 3 mm when the probe tip was held 3 to 5 mm from the tissue surface. The axial resolution was 6 ?m and the lateral resolution was 30-35 ?m. The 25-gauge forward-imaging probe was used to image cellophane tape, eyelid skin, cornea, conjunctiva, sclera, iris, anterior lens, anterior chamber angle, retina, retinal tear, retinal detachment, optic nerve head, and optic nerve sheath. Images obtained from the miniature probe appeared similar to images from a 3 mm scanning range of a commercial large handheld OCT probe (Bioptigen, Inc. Durham, NC).

Joos, Karen M.; Shen, Jin-Hui

2012-03-01

151

A comprehensive method for optical-emission computed tomography  

Science.gov (United States)

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.

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

2010-07-01

152

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

Directory of Open Access Journals (Sweden)

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

A. Stella

2011-02-01

153

Optical coherence tomography and autofluorescence imaging of human tonsil.  

Science.gov (United States)

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

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

2014-01-01

154

Low-cost diffuse optical tomography for the classroom  

Science.gov (United States)

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

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

2012-10-01

155

Optical Coherence Tomography and Autofluorescence Imaging of Human Tonsil  

Science.gov (United States)

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

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

2014-01-01

156

Multispectral guided fluorescence diffuse optical tomography using upconverting nanoparticles  

International Nuclear Information System (INIS)

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

157

The Giant Magellan Telescope Laser Tomography Adaptive Optics System  

Science.gov (United States)

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.

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

158

Piezoelectric scanning mirrors for endoscopic optical coherence tomography  

International Nuclear Information System (INIS)

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

159

Liquid sorption investigation of porous media by optical coherence tomography  

International Nuclear Information System (INIS)

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

160

In vivo endoscopic multi-beam optical coherence tomography.  

Science.gov (United States)

A multichannel optical coherence tomography (multi-beam OCT) system and an in vivo endoscopic imaging probe were developed using a swept-source OCT system. The distal optics were micro-machined to produce a high numerical aperture, multi-focus fibre optic array. This combination resulted in a transverse design resolution of width half maximum (FWHM) throughout the entire imaging range, while also increasing the signal intensity within the focus of the individual channels. The system was used in a pre-clinical rabbit study to acquire in vivo structural images of the colon and ex vivo images of the oesophagus and trachea. A good correlation between the structural multi-beam OCT images and H&E histology was achieved, demonstrating the feasibility of this high-resolution system and its potential for in vivo human endoscopic imaging. PMID:20071753

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

2010-02-01

 
 
 
 
161

A Low-Cost Method for Optical Tomography  

Directory of Open Access Journals (Sweden)

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

Mohammad Ali Ansari

2012-07-01

162

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

Science.gov (United States)

The strong optical scattering of skin tissue makes it very difficult for optical coherence tomography (OCT) to achieve deep imaging in skin. Significant optical clearing of in vivo rat skin sites was achieved within 15 min by topical application of an optical clearing agent PEG-400, a chemical enhancer (thiazone or propanediol), and physical massage. Only when all three components were applied together could a 15 min treatment achieve a three fold increase in the OCT reflectance from a 300 ?m depth and 31% enhancement in image depth Z(threshold). PMID:22734778

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

2012-06-01

163

Reflective afocal adaptive optics: optical coherence tomography retinal imaging system  

Science.gov (United States)

We present a new design for a reflective afocal AO-OCT retinal imaging system. The optical performance of this instrument is compared to our previous multimodal AO-OCT/AO-SLO retinal imaging system. The feasibility of new instrumentation for improved visualization of microscopic retinal structures will be discussed. Examples of images acquired with this new AO-OCT instrument will be presented.

Lee, Sang Hyuck; Werner, John S.; Zawadzki, Robert J.

2013-03-01

164

Optical coherence tomography of pneumatic displacement of optic disc pit maculopathy  

Digital Repository Infrastructure Vision for European Research (DRIVER)

BACKGROUND—The authors have previously concluded that fluid from an optic disc pit creates an inner layer separation (ILS) of the retina. An outer layer detachment (OLD) centred on the macula is a secondary phenomenon that causes a dense central scotoma. Pneumatic displacement of the OLD effects an improvement in central vision. Pathology to confirm these conclusions is lacking. Intraretinal images obtained by optical coherence tomography (OCT), however, are confirmatory.?METHODS—Three ...

Lincoff, H.; Kreissig, I.

1998-01-01

165

Extended depth of focus adaptive optics spectral domain optical coherence tomography  

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We present an adaptive optics spectral domain optical coherence tomography (AO-SDOCT) with a long focal range by active phase modulation of the pupil. A long focal range is achieved by introducing AO-controlled third-order spherical aberration (SA). The property of SA and its effects on focal range are investigated in detail using the Huygens-Fresnel principle, beam profile measurement and OCT imaging of a phantom. The results indicate that the focal range is extended by applyi...

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

2012-01-01

166

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

We report a noble optical sensing method to diagnose seed abnormalities using optical coherence tomography (OCT). Melon seeds infected with Cucumber green mottle mosaic virus (CGMMV) were scanned by OCT. The cross-sectional sensed area of the abnormal seeds showed an additional subsurface layer under the surface which is not found in normal seeds. The presence of CGMMV in the sample was examined by a blind test (n = 140) and compared by the reverse transcription-polymerase chain reaction. The...

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

2011-01-01

167

Adaptive optics: optical coherence tomography system for in-vivo imaging of the mouse retina  

Science.gov (United States)

We present a custom fourier domain optical coherence tomography imaging system for high resolution imaging of mouse retina. In order to overcome aberrations in the mouse eye, we incorporated an adaptive optics system into the sample arm of the OCT system. We used a refraction cancelling lens to minimize aberrations from the cornea, as well as reduce the specular back-reflection. Results of FDOCT images of mouse retina acquired in vivo with and without AO are presented.

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

2012-01-01

168

Spectral Domain Optical Coherence Tomography and Adaptive Optics: Imaging Photoreceptor Layer Morphology to Interpret Preclinical Phenotypes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Recent years have seen the emergence of advances in imaging technology that enable in vivo evaluation of the living retina. Two of the more promising techniques, spectral domain optical coherence tomography (SD-OCT) and adaptive optics (AO) fundus imaging provide complementary views of the retinal tissue. SD-OCT devices have high axial resolution, allowing assessment of retinal lamination, while the high lateral resolution of AO allows visualization of individual cells. The potential exists t...

Rha, Jungtae; Dubis, Adam M.; Wagner-schuman, Melissa; Tait, Diane M.; Godara, Pooja; Schroeder, Brett; Stepien, Kimberly; Carroll, Joseph

2010-01-01

169

Adaptive optics optical coherence tomography for in vivo mouse retinal imaging  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

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

2013-01-01

170

Error Budget Analysis for an Adaptive Optics Optical Coherence Tomography System  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The combination of adaptive optics (AO) technology with optical coherence tomography (OCT) instrumentation for imaging the retina has proven to be a valuable tool for clinicians and researchers in understanding the healthy and diseased eye. The micrometer-isotropic resolution achieved by such a system allows imaging of the retina at a cellular level, however imaging of some cell types remains elusive. Improvement in contrast rather than resolution is needed and can be achieved through better ...

Evans, Julia W.; Zawadzki, Robert J.; Jones, Steven M.; Olivier, Scot S.; Werner, John S.

2009-01-01

171

Adaptive-optics optical coherence tomography processing using a graphics processing unit.  

Science.gov (United States)

Graphics processing units are increasingly being used for scientific computing for their powerful parallel processing abilities, and moderate price compared to super computers and computing grids. In this paper we have used a general purpose graphics processing unit to process adaptive-optics optical coherence tomography (AOOCT) images in real time. Increasing the processing speed of AOOCT is an essential step in moving the super high resolution technology closer to clinical viability. PMID:25570838

Shafer, Brandon A; Kriske, Jeffery E; Kocaoglu, Omer P; Turner, Timothy L; Zhuolin Liu; Lee, John Jaehwan; Miller, Donald T

2014-08-01

172

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

Purpose: The aim was to study optic nerve head (ONH) parameters in normal Indian eyes using spectral domain optical coherence tomography (OCT)/scanning laser ophthamoscope (SLO). Materials and Methods: One hundred and fifty-seven eyes of 157 normal subjects of various age groups underwent ONH imaging with spectral OCT/SLO and the parameters obtained were correlated with disc size. The effect of age, gender, and refractive error on various ONH parameters were also studied. Res...

Mansoori Tarannum; Viswanath Kalluri; Balakrishna Nagalla

2011-01-01

173

Reflectance diffuse optical tomography. Its application to human brain mapping  

International Nuclear Information System (INIS)

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

174

Capturing the vital vascular fingerprint with optical coherence tomography.  

Science.gov (United States)

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

Liu, Gangjun; Chen, Zhongping

2013-08-01

175

Handheld Optical Coherence Tomography Scanner for Primary Care Diagnostics  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2011-01-01

176

[Optical coherence tomography aspects of Stargardt's disease: case report].  

Science.gov (United States)

The term fundus flavimaculatus (Stargardt disease) describes a group of inherited macular dystrophies characterized by multiple yellow to yellow-white flecks at the level of the retinal pigment epithelium. The authors describe findings in the patient with Stargardt's disease using optical coherence tomography (OCT), and suggest the examination to be valid as subsidiary method in the study of the characteristics of the retina in Stargardt's disease patients, but studies involving a series of patients should be able to show the most frequent findings in these cases. PMID:17119737

Gouveia, Enéias Bezerra; Morales, Maira Saad de Avila; Allemann, Norma; Matte, Guilherme; Berezovsky, Adriana; Sallum, Juliana Maria Ferraz

2006-01-01

177

Optical coherence tomography in art diagnostics and restoration  

Science.gov (United States)

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

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

2008-07-01

178

Segmentation of ophthalmic optical coherence tomography images using graph cuts  

Science.gov (United States)

We describe an efficient approach for the automated segmentation of pathological/morphological structures in ophthalmic Spectral Domain Optical Coherence Tomography (SDOCT) images. In this algorithm, image pixels are treated as nodes of a graph with edge weights assigned to associate pairs of pixels. The weights vary according to the distances, brightness differences, and feature variations between pixel pairs. Cuts through the graph with minimum accumulated weights correspond to morphological layer boundaries. This approach has been applied to SDOCT images with encouraging results and thus forms an adaptable framework for the segmentation of many different ophthalmic structures.

Li, Xiao T.; Chiu, Stephanie J.; Nicholas, Peter; Toth, Cynthia A.; Izatt, Joseph A.; Farsiu, Sina

2010-02-01

179

High-speed optical coherence tomography using fiberoptic acousto-optic phase modulation  

Science.gov (United States)

We report a new rapid-scanning optical delay device suitable for high-speed optical coherence tomography (OCT) in which an acousto-optic modulator (AOM) is used to independently modulate the Doppler frequency shift of the reference light beam for optical heterodyne detection. Experimental results show that the fluctuation of the measured Doppler frequency shift is less than +/-0.2% over 95% duty cycle of OCT imaging, thus allowing for enhanced signal-to-noise ratio of optical heterodyne detection. The increased Doppler frequency shift by AOM also permits complete envelop demodulation without the compromise of reducing axial resolution; if used with a resonant rapid-scanning optical delay, it will permit high-performance real-time OCT imaging. Potentially, this new rapid-scanning optical delay device will improve the performance of high-speed Doppler OCT techniques.

Xie, Tuqiang; Wang, Zhenguo; Pan, Yingtian

2003-12-01

180

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

Directory of Open Access Journals (Sweden)

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

Juan Liu

2013-11-01

 
 
 
 
181

Characterizing matrix remodeling in collagen gels using optical coherence tomography  

Science.gov (United States)

Optical coherence tomography (OCT) has shown promise at non-destructively characterizing engineered tissues such as collagen gels. However, as the collagen gels develop, the OCT images lose contrast of structures as the gels develop, making visual assessment difficult. Our group proposed quantitatively characterizing these gels by fitting the optical properties from the OCT signals. In this paper, we imaged collagen gels seeded with smooth muscle cells (SMCs) over a 5-day period and used the data to measure their optical properties. Our results showed that over time, the reflectivity of the samples increased 10-fold, corresponding to a decrease in anisotropy factor g, without much change in the scattering coefficient ?s. Overall, the optical properties appeared to be dominated by scattering from the collagen matrix, not the cells. However, SMCs remodeled the collagen matrix, and this collagen remodeling by the cells is what causes the observed changes in optical properties. Moreover, the data showed that the optical properties were sensitive to the activity of matrix metalloproteinases (MMPs), enzymes that break down local collagen fibrils into smaller fragments. Blocking MMPs in the SMC gels greatly impeded both the remodeling process and change in optical properties at day 5. Treating day 1 acellular gels with MMP-8 for 3 hr managed to partially reproduce the remodeling observed in SMC gels at day 5. Altogether, we conclude that matrix remodeling in general, and MMPs specifically, greatly affect the local optical properties of the sample, and OCT is a unique tool that can assess MMP activity in collagen gels both non-destructively and label free.

Levitz, David; Hinds, Monica T.; Hanson, Stephen R.; Jacques, Steven L.

2010-02-01

182

Optical tomography for measuring dose distribution in radiation therapy  

Directory of Open Access Journals (Sweden)

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.

Kauppinen Matti

2014-01-01

183

Quantitative characterization of developing collagen gels using optical coherence tomography  

Science.gov (United States)

Nondestructive optical imaging methods such as optical coherence tomography (OCT) have been proposed for characterizing engineered tissues such as collagen gels. In our study, OCT was used to image collagen gels with different seeding densities of smooth muscle cells (SMCs), including acellular gels, over a five-day period during which the gels contracted and became turbid with increased optical scattering. The gels were characterized quantitatively by their optical properties, specified by analysis of OCT data using a theoretical model. At 6 h, seeded cell density and scattering coefficient (?s) were correlated, with ?s equal to 10.8 cm-1/(106 cells/mL). Seeded cell density and the scattering anisotropy (g) were uncorrelated. Over five days, the reflectivity in SMC gels gradually doubled with little change in optical attenuation, which indicated a decrease in g that increased backscatter, but only a small drop in ?s. At five days, a subpopulation of sites on the gel showed substantially higher reflectivity (approximately a tenfold increase from the first 24 h). In summary, the increased turbidity of SMC gels that develops over time is due to a change in the structure of collagen, which affects g, and not simply due to a change in number density of collagen fibers due to contraction.

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

2010-03-01

184

Diffuse optical tomography with a priori anatomical information  

International Nuclear Information System (INIS)

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

185

Optical Coherence Tomography for Examination of Parchment Degradation  

International Nuclear Information System (INIS)

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

186

Sound field reconstruction using acousto-optic tomography  

DEFF Research Database (Denmark)

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

Torras Rosell, Antoni; Barrera Figueroa, Salvador

2012-01-01

187

Performance of latex balloons for optical computed tomography  

International Nuclear Information System (INIS)

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.

188

Retinal oximetry using ultrahigh-resolution optical coherence tomography  

Directory of Open Access Journals (Sweden)

Full Text Available Yufeng Ye,1,2 Hong Jiang,2,3 Meixiao Shen,4 Byron L Lam,2 Delia Cabrera DeBuc,2 Lili Ge,2,4 Mitra Sehi,2 Jianhua Wang21Hangzhou First People’s Hospital, Hangzhou, China; 2Bascom Palmer Eye Institute, 3Neurology, University of Miami, Miami, FL, USA; 4School of Ophthalmology and Optometry, Wenzhou Medical College, Wenzhou, Zhejiang, ChinaBackground: The purpose of this study was to investigate the repeatability of retinal oximetry using slit-lamp adapted ultrahigh-resolution optical coherence tomography (SL-UHR-OCT.Methods: SL-UHR-OCT was developed and fringe patterns were obtained for a major retinal artery and a major retinal vein. A-scans at the central wavelengths of 805 nm and 855 nm were analyzed for calculating optical density ratios (ODRs, from which the percentage oxygen saturation was calculated. Measurements were made on two occasions for each person. Repeatability and coefficients of repeatability were calculated.Results: The mean ODRs of the artery were 0.79 ± 0.86 and 0.88 ± 0.97 in sessions 1 and 2, respectively. The mean ODRs of the vein were ?0.08 ± 0.69 and 0.14 ± 0.77 between the two sessions, and were significantly lower than that of the artery (P < 0.05. The coefficients of repeatability were 1.44 and 1.81 for the artery and vein, respectively. The mean oxygen saturation of the major retinal artery was 94% ± 45% and 98% ± 51% in sessions 1 and 2, respectively, and the mean oxygen saturation of the major retinal vein was 48% ± 36% and 60% ± 40% between sessions.Conclusion: Optical coherence tomographic oximetry for evaluating retinal oxygen saturation was subject to variation, although the averaged measurements in repeated sessions were matched. Further work on reducing variation will be needed.Keywords: ultrahigh-resolution optical coherence tomography, oximetry

Ye Y

2012-12-01

189

Macular optical coherence tomography findings following blunt ocular trauma  

Directory of Open Access Journals (Sweden)

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

Oladiwura D

2014-05-01

190

Cell death monitoring using quantitative optical coherence tomography methods  

Science.gov (United States)

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.

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

2011-03-01

191

High-speed optical coherence tomography signal processing on GPU  

International Nuclear Information System (INIS)

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

192

Parallel multithread computing for spectroscopic analysis in optical coherence tomography  

Science.gov (United States)

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

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

2014-05-01

193

Endoscopic Bio-Imaging Using Optical Coherence Tomography  

International Nuclear Information System (INIS)

Optical coherence tomography(OCT) is an emerging medical diagnostic tool that draws great attention in medical and biological fields. It has a 10-100 times higher spatial resolution than that of the clinical ultrasound but lower imaging depth such as 1-2 mm. In order to image internal organs, OCT needs an endoscopic probe. In this paper, the principle of Fourier-domain optical coherence tomography with high-speed imaging capability was introduced. An OCT endoscope based on MEMS technology was developed. It was attached to the Fourier-domain OCT system to acquire three-dimensional tomographic images of gastrointestinal tract of New Zealand white rabbit. The endoscope had a two-axis scanning mirror that was driven by electrostatic force. The mirror stirred an incident light to sweep two-dimensional plane by scanning. The outer diameter of the endoscope was 6 mm and the mirror diameter was 1.2 mm. A three-dimensional image rendered by 200 two-dimensional tomographs with 200x500 pixels was displayed within 3.5 seconds. The spatial resolution of the OCT system was 8 ?m in air

194

High-speed optical coherence tomography signal processing on GPU  

Energy Technology Data Exchange (ETDEWEB)

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).

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

195

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

2010-09-07

196

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

Energy Technology Data Exchange (ETDEWEB)

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

Shi, G H [Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209 (China); Ding, Z H [State Key Lab of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310027 (China); Dai, Y [Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209 (China); Rao, X J [Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209 (China); Zhang, Y D [Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209 (China)

2006-10-15

197

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

International Nuclear Information System (INIS)

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

198

Experimental demonstration of an analytic method for image reconstruction in optical tomography with large data sets  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We report the first experimental test of an analytic image reconstruction algorithm for optical tomography with large data sets. Using a continuous-wave optical tomography system with 10^8 source-detector pairs, we demonstrate the reconstruction of an absorption image of a phantom consisting of a highly-scattering medium with absorbing inhomogeneities.

Wang, Zheng-min; Panasyuk, George Y.; Markel, Vadim A.; Schotland, John C.

2005-01-01

199

Full-field optical coherence tomography system implemented with fiber-optic components  

Science.gov (United States)

We have presented full-field optical coherence tomography(FF-OCT) system implemented with fiber optics. Usually FFOCT system illuminates large area at once while conventional OCT system irradiates light at single focal point. From these reason, light guidance with single fiber waveguide is not proper in FF-OCT system and fiber-optic components is not dealt in the system implementation. In this paper, we demonstrate FF-OCT system implemented with fiber-optics, where fiber coupler and fiber-optic circulator were used to perform the function of beam splitting and optical delay line. Each arm of fiber coupler acts as reference arm and sample arm. Fiber-optic collimator and metal-coated mirror mounted on translator in the reference arm could adjust optical path length properly. Separated beam after the fiber coupler was combined after bulk beam combiner, where beam size at fiber end is expanded by large fiber-optic collimator and then illuminated to sample. The larger size beam reflected from sample was interfered with reference beam, which experienced optical delay in the reference arm. The utilization of fiber-optic components could provide merits such as easiness in optical alignment and reduction of sensitiveness to external vibration and perturbation.

Lee, Seung Suk; Kim, Joo Ha; Choi, Eun Seo

2014-02-01

200

Integrated modeling of the GMT laser tomography adaptive optics system  

Science.gov (United States)

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

Piatrou, Piotr

2014-08-01

 
 
 
 
201

Multiplex optical sensors for reference structure tomography and compressive spectroscopy  

Science.gov (United States)

With the emergence of ubiquitous embedded digital processing and inexpensive focal planes, imaging and sensor systems that integrate optical and electronic processing have increasingly become attractive. These systems are regarded as "integrated computational imaging systems" because they use non-conventional optical elements to preprocess the field for digital analysis. Computational imaging systems, also referred to as multiplex imagers, are particularly attractive as they achieve increased depth of field, multidimensional or multispectral imaging, improved data or computational efficiency and improved target recognition or tracking capabilities. Some of the capabilities of these computational systems are: multidimensional imaging, source analysis, data compression and analysis and sensor array data fusion. In this thesis, a novel computational imaging system termed "Reference structure tomography (RST)" is proposed. RST makes use of a new form of volume optical element, a tomographic reference structure which modulates the visibility of the source space to improve the efficiency of object analysis. This thesis will describe RST and demonstrate three-dimensional imaging and source analysis with reference structures. This thesis also proposes a new multiplex optical sensing system for compressive sampling in the physical layer. Compressive sampling enables signal reconstruction using fewer than one measurement per estimated signal value. A measurement efficient optical wavemeter and a compressive spectrometer will be described to demonstrate compressive sampling. The optical wavemeter efficiently measures the spectral densities of quasi-monochromatic and spectrally sparse sources. The compressive spectrometer measures the spectrum of a broad-band source with fewer measurements than the number of estimated spectral channels. The compressive spectrometer is designed to physically measure the Haar wavelet coefficients of the spectral source and the spectrum is estimated from these coefficients.

Potuluri, Prasant

202

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

Science.gov (United States)

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

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

2013-01-28

203

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

Science.gov (United States)

Optical coherence tomography (OCT), based on a Michelson interferometer and utilizing low coherence light as the optical source, is a novel technique for the noninvasive imaging of optical scattering media. A simple OCT scheme based on a 3 x 3 fiber coupler is presented for the simultaneous measurement of the refractive index and thickness of optical samples. The proposed system enables the refractive index and thickness to be determined without any prior knowledge of the sample parameters and is characterized by a simple and compact configuration, a straightforward measurement procedure, and a low cost. The feasibility of the proposed approach is demonstrated experimentally using BK7 and B270 optical glass samples. PMID:20154745

Cheng, Hsu-Chih; Liu, Yi-Cheng

2010-02-10

204

Investigation of swelling behaviour in strongly scattering porous media using optical coherence tomography  

International Nuclear Information System (INIS)

This paper presents an optical method to measure independently the effect of swelling on the optical properties of strongly scattering porous media. The method was tested by measuring the swelling behaviour of cellulose fibre tissue using optical coherence tomography. The experimental results proved that the effect of swelling on optical and physical properties of paper can be measured

205

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

DEFF Research Database (Denmark)

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

Precht, Helle; Leth, Peter Mygind

2014-01-01

206

Dynamic optical coherence tomography in studies of optical clearing, sedimentation, and aggregation of immersed blood  

Science.gov (United States)

The concept of refractive-index matching to enhance the optical penetration depth of whole blood is discussed on the basis of in vitro studies that used the technique of near-infrared optical coherence tomography. It was found that optical clearing of blood is defined not only by refractive-index matching but also by changes in the size of red blood cells and in their aggregation ability when chemicals are added. For example, in whole blood diluted to twice its volume by saline with the addition of 6.5% glycerol, the total attenuation coefficient was reduced from 4.2 to 2.0 mm-1, and the optical penetration at 820 nm was correspondingly increased to 117%. For the other agents tested (glucose, dextrans, propylene glycol, and trazograph) the enhancement of penetration was 20-150.5%. In the blood sedimentation study, regular or irregular oscillations or jumps of the red-blood cell-plasma boundary were observed. The 1-min time period of regular oscillations correlated well with the kinetics of the aggregation process as described by the two subsequent stages of formation of linear and three-dimensional aggregates. The results also showed that optical clearing of blood by osmotic agents is potentially useful not only in blood sedimentation and aggregation studies but also in intravascular optical coherence tomography imaging techniques.

Tuchin, Valery V.; Xu, Xiangqun; Wang, Ruikang K.

2002-01-01

207

Approach to retina optical coherence tomography image processing  

Science.gov (United States)

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

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

2007-03-01

208

Functional imaging of small tissue volumes with diffuse optical tomography  

Science.gov (United States)

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

Klose, Alexander D.; Hielscher, Andreas H.

2006-03-01

209

Compact piezoelectric transducer fiber scanning probe for optical coherence tomography.  

Science.gov (United States)

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 ?m 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 ?m axial resolution (in air). En face OCT imaging of skin in vivo and human colon ex vivo was demonstrated. PMID:24562102

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

2014-01-15

210

Handheld simultaneous scanning laser ophthalmoscopy and optical coherence tomography system.  

Science.gov (United States)

Scanning laser ophthalmoscopy (SLO) and optical coherence tomography (OCT) are widely used retinal imaging modalities that can assist in the diagnosis of retinal pathologies. The combination of SLO and OCT provides a more comprehensive imaging system and a method to register OCT images to produce motion corrected retinal volumes. While high quality, bench-top SLO-OCT systems have been discussed in the literature and are available commercially, there are currently no handheld designs. We describe the first design and fabrication of a handheld SLO/spectral domain OCT probe. SLO and OCT images were acquired simultaneously with a combined power under the ANSI limit. High signal-to-noise ratio SLO and OCT images were acquired simultaneously from a normal subject with visible motion artifacts. Fully automated motion estimation methods were performed in post-processing to correct for the inter- and intra-frame motion in SLO images and their concurrently acquired OCT volumes. The resulting set of reconstructed SLO images and the OCT volume were without visible motion artifacts. At a reduced field of view, the SLO resolved parafoveal cones without adaptive optics at a retinal eccentricity of 11° in subjects with good ocular optics. This system may be especially useful for imaging young children and subjects with less stable fixation. PMID:24298396

Larocca, Francesco; Nankivil, Derek; Farsiu, Sina; Izatt, Joseph A

2013-01-01

211

Metrological reliability of optical coherence tomography in biomedical applications  

International Nuclear Information System (INIS)

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

212

Phenotyping transgenic embryonic murine hearts using optical coherence tomography  

Science.gov (United States)

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).

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

2007-04-01

213

Imaging nanoparticle flow using magneto-motive optical Doppler tomography  

International Nuclear Information System (INIS)

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

214

Implementation of an Optical Coherence Tomography system for painting characterization  

International Nuclear Information System (INIS)

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

215

Signal processing in optical coherence tomography for aerospace material characterization  

Science.gov (United States)

Based on a customized time-domain optical coherence tomography (OCT) system, a series of signal processing approaches have been designed and reviewed. To improve demodulation accuracy and image quality, demodulation approaches such as median filter, Hilbert transform, and envelope detector were investigated with simulated as well as experimental data. Without noise, the Hilbert transform has the best performance, but after considering the narrow-band noise in the modulated signal, the envelope detector was selected as the ideal demodulation technique. To reduce noise and enhance image contrast, digital signal processing techniques such as a bandpass filtering and two-dimensional median filtering were applied before and after the demodulation, respectively. Finally with integration of the customized OCT setup and designed signal processing algorithms, aerospace materials, such as polymer coatings and glass-fiber composites, were successfully characterized. The cross-sectional images obtained clearly show the microstructures of the materials.

Liu, Ping; Groves, Roger M.; Benedictus, Rinze

2013-03-01

216

Monte Carlo modeling of angiographic optical coherence tomography.  

Science.gov (United States)

Optical coherence tomography (OCT) provides both structural and angiographic imaging modes. Because of its unique capabilities, OCT-based angiography has been increasingly adopted into small animal and human subject imaging. To support the development of the signal and image processing algorithms on which OCT-based angiography depends, we describe here a Monte Carlo-based model of the imaging approach. The model supports arbitrary three-dimensional vascular network geometries and incorporates methods to simulate OCT signal temporal decorrelation. With this model, it will be easier to compare the performance of existing and new angiographic signal processing algorithms, and to quantify the accuracy of vascular segmentation algorithms. The quantitative analysis of key algorithms within OCT-based angiography may, in turn, simplify the selection of algorithms in instrument design and accelerate the pace of new algorithm development. PMID:25574442

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

2014-12-01

217

Optical coherence tomography following successful management of endophthalmitis  

Directory of Open Access Journals (Sweden)

Full Text Available Optical coherence tomography (OCT was done in 20 eyes to detect causes of poor visual outcome, at least three months after successful management of endophthalmitis, which obtained clear media and best corrected visual acuity of < 20/40. Only four (20% eyes had normal foveal contour on OCT. Eleven (55% eyes showed treatable lesions, including epiretinal membrane with macular thickening in five (25%, epiretinal membrane without macular thickening in three (15%, cystoid macular edema in two (10% and subfoveal serous detachment in one (5% eye. Five eyes (25% had foveal atrophy. OCT was helpful in segregating treatable conditions like cystoid macular edema from nontreatable causes like neurosensory atrophy in the postendophthalmitis patients.

Singh Ramandeep

2007-01-01

218

Pre-seizure state identified by diffuse optical tomography  

Science.gov (United States)

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.

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

2014-01-01

219

Scalable multiplexing for parallel imaging with interleaved optical coherence tomography  

Science.gov (United States)

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

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

2014-01-01

220

Evaluation of microfluidic channels with optical coherence tomography  

Science.gov (United States)

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.

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

2010-11-01

 
 
 
 
221

Tissue clearing of biotissues for optical coherence tomography  

Science.gov (United States)

The high scattering nature of non-transparent human tissue limits the imaging depth of optical coherence tomography (OCT) to 1-2 millimeters. By using the longer wavelength of the light source, the penetration depth is improved; the imaging contrast is however decreased largely due to the reduced backscattering in microscopic scale and the reduced refractive heterogeneity in macroscopic scale. For more effective diagnosis using OCT, a concurrent improvement of penetration depth and imaging contrast are often needed. We report in this paper that the OCT imaging depth and contrast can be enhanced concurrently by the use of osmotic agents. We demonstrate experimentally, by examples, that the topical applications of glycerol and propylene glycol, two common biocompatible and osmotically active solutions, onto the tissue surfaces could significantly improve the OCT imaging contrast and depth capability. The biotissues demonstrated include the rat skin, human oesophageal and gastric tissues.

Wang, Ruikang K.

2002-09-01

222

Detection and analysis of jade material using optical coherence tomography  

Science.gov (United States)

Jade is a type of rare and expensive stone. The current approaches for jade exploration and processing are blindly and wasteful. Capable of performing high resolution, cross-sectional sensing of the internal structure of materials, Optical Coherence Tomography (OCT) could be used to greatly facilitate these jade procedures. By detecting the signal intensity and analysing the internal texture, OCT system can indicate if the jade exists and what the type it could be. It provides a tool to guide the artist in designing and making the jade artworks. It also can be used for discrimination of the fake antique jade wares, as well as anti-counterfeiters on the jade market. In this paper, we present how a Swept-Source OCT system to detect and analysis the internal features of jades. Algorithms for feature extraction and classification are described and experimental results with various unearthed jades are demonstrated.

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

2010-06-01

223

Optical coherence tomography in the diagnosis and management of uveitis.  

Science.gov (United States)

Optical coherence tomography (OCT) has become an integral tool in the imaging of numerous diseases of the posterior segment. The diagnostic investigation of infectious and noninfectious uveitic conditions often requires multiple imaging modalities in the appropriate clinical context. Modern OCT technology has proved useful not only in the diagnostic investigation of these conditions, but also in monitoring of their clinical course and therapeutic response. Inflammation-induced changes at the level of the retina, retinal pigment epithelium, and choroid can now easily be identified in these conditions using OCT. Prognostic information on visual acuity outcome can also be estimated based on OCT findings. Numerous OCT findings have been described in the setting of the various uveitides. Although none of these findings appear to be pathognomonic for diagnosis of specific uveitic syndromes, in the appropriate clinical context they can add a great deal of information in the diagnosis and management of uveitis. PMID:24513352

Pakzad-Vaezi, Kaivon; Or, Chris; Yeh, Steven; Forooghian, Farzin

2014-02-01

224

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

Science.gov (United States)

In this work, we proposed a novel three-dimensional compressive sensing (CS) approach for spectral domain optical coherence tomography (SD OCT) volumetric image acquisition and reconstruction. Instead of taking a spectral volume whose size is the same as that of the volumetric image, our method uses a sub set of the original spectral volume that is under-sampled in all three dimensions, which reduces the amount of spectral measurements to less than 20% of that required by the Shan-non/Nyquist theory. The 3D image is recovered from the under-sampled spectral data dimension-by-dimension using the proposed three-step CS reconstruction strategy. Experimental results show that our method can significantly reduce the sampling rate required for a volumetric SD OCT image while preserving the image quality. PMID:25426320

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

2014-11-01

225

Characterization and Analysis of Relative Intensity Noise in Broadband Optical Sources for Optical Coherence Tomography  

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Relative intensity noise (RIN) is one of the most significant factors limiting the sensitivity of an optical coherence tomography (OCT) system. The existing and prevalent theory being used for estimating RIN for various light sources in OCT is questionable, and cannot be applied uniformly for different types of sources. The origin of noise in various sources differs significantly, owing to the different physical nature of photon generation. In this study, we characterize and compare RIN of se...

Shin, Sunghwan; Sharma, Utkarsh; Tu, Haohua; Jung, Woonggyu; Boppart, Stephen A.

2010-01-01

226

Image features of punctate inner choroiditis on optical coherence tomography  

Directory of Open Access Journals (Sweden)

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.

Hao Zhang

2014-05-01

227

A tissue equivalent phantom for simultaneous near-infrared optical tomography and EEG.  

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We describe a phantom which enables EEG and near-infrared optical tomography to be performed simultaneously over the same volume. The phantom provides a surface electrical contact impedance comparable to that of the human scalp, whilst also possessing an optical scattering coefficient and electrical conductivity equivalent to that of brain tissue. The construction of the phantom is described, as is the resulting simultaneous EEG and near infrared optical tomography experiment, which, to our k...

Cooper, R. J.; Eames, R.; Brunker, J.; Enfield, L. C.; Gibson, A. P.; Hebden, J. C.

2010-01-01

228

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

International Nuclear Information System (INIS)

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

229

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

International Nuclear Information System (INIS)

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

230

Extended depth of focus adaptive optics spectral domain optical coherence tomography  

Science.gov (United States)

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

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

2012-01-01

231

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

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

Xu, Xiangqun; Yu, Lingfeng; Chen, Zhongping

2008-01-01

232

Adaptive optics–optical coherence tomography: optimizing visualization of microscopic retinal structures in three dimensions  

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Adaptive optics–optical coherence tomography (AO-OCT) permits improved imaging of microscopic retinal structures by combining the high lateral resolution of AO with the high axial resolution of OCT, resulting in the narrowest three-dimensional (3D) point-spread function (PSF) of all in vivo retinal imaging techniques. Owing to the high volumetric resolution of AO-OCT systems, it is now possible, for the first time, to acquire images of 3D cellular structures in the living retina. Thus, with...

Zawadzki, Robert J.; Choi, Stacey S.; Jones, Steven M.; Oliver, Scot S.; Werner, John S.

2007-01-01

233

Imaging retinal nerve fiber bundles using optical coherence tomography with adaptive optics  

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Early detection of axonal tissue loss in retinal nerve fiber layer (RNFL) is critical for effective treatment and management of diseases such as glaucoma. This study aims to evaluate the capability of ultrahigh-resolution optical coherence tomography with adaptive optics (UHR-AO-OCT) for imaging the RNFL axonal bundles (RNFBs) with 3×3×3 ?m3 resolution in the eye. We used a research-grade UHR-AO-OCT system to acquire 3°×3° volumes in four normal subjects and one subject with an arcuate ...

Kocaoglu, Omer P.; Cense, Barry; Jonnal, Ravi S.; Wang, Qiang; Lee, Sangyeol; Gao, Weihua; Miller, Donald T.

2011-01-01

234

Retinal imaging with polarization-sensitive optical coherence tomography and adaptive optics  

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Various layers of the retina are well known to alter the polarization state of light. Such changes in polarization may be a sensitive indicator of tissue structure and function, and as such have gained increased clinical attention. Here we demonstrate a polarization-sensitive optical coherence tomography (PS-OCT) system that incorporates adaptive optics (AO) in the sample arm and a single line scan camera in the detection arm. We quantify the benefit of AO for PS-OCT in terms of signal-to-noi...

Cense, B.; Gao, W. H.; Brown, J. M.; Jones, S. M.; Jonnal, R. S.; Mujat, M.; Park, B. H.; Boer, J. F.; Miller, D. T.

2009-01-01

235

Construction of the Optical Delay Line for the Optical Coherence Tomography  

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

Kitsakorn Locharoenrat

2013-03-01

236

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

Science.gov (United States)

We report a polarization diversity detection scheme for optical coherence tomography with a new, custom, miniaturized fiber coupler with single mode (SM) fiber inputs and polarization maintaining (PM) fiber outputs. The SM fiber inputs obviate matching the optical lengths of the X and Y OCT polarization channels prior to interference and the PM fiber outputs ensure defined X and Y axes after interference. Advantages for this scheme include easier alignment, lower cost, and easier miniaturization compared to designs with free-space bulk optical components. We demonstrate the utility of the detection system to mitigate the effects of rapidly changing polarization states when imaging with rotating fiber optic probes in Intralipid suspension and during in vivo imaging of human airways. PMID:24978556

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

2014-06-15

237

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

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We acquired in vivo images of the human optic nerve head (ONH) using an adaptive optics—optical coherence tomography (AO-OCT) system. In order to improve imaging of the lamina cribrosa in the ONH with high lateral resolution and sensitivity, we implemented a complex conjugate artifact-free Fourier domain OCT (Fd-OCT) acquisition scheme with a reference arm-based phase shifting method. This allowed positioning of the lamina cribrosa structures near the zero path length difference where AO-OC...

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

2012-01-01

238

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

Science.gov (United States)

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.

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

2012-02-01

239

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

Science.gov (United States)

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

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

2006-02-01

240

Retina-simulating phantom for optical coherence tomography.  

Science.gov (United States)

Optical coherence tomography (OCT) is a rapidly growing imaging modality, particularly in the field of ophthalmology. Accurate early diagnosis of diseases requires consistent and validated imaging performance. In contrast to more well-established medical imaging modalities, no standardized test methods currently exist for OCT quality assurance. We developed a retinal phantom which mimics the thickness and near-infrared optical properties of each anatomical retinal layer as well as the surface topography of the foveal pit. The fabrication process involves layer-by-layer spin coating of nanoparticle-embedded silicone films followed by laser micro-etching to modify the surface topography. The thickness of each layer and dimensions of the foveal pit are measured with high precision. The phantom is embedded into a commercially available, water-filled model eye to simulate ocular dispersion and emmetropic refraction, and for ease of use with clinical OCT systems. The phantom was imaged with research and clinical OCT systems to assess image quality and software accuracy. Our results indicate that this phantom may serve as a useful tool to evaluate and standardize OCT performance. PMID:24042445

Baxi, Jigesh; Calhoun, William; Sepah, Yasir Jamal; Hammer, Daniel X; Ilev, Ilko; Pfefer, T Joshua; Nguyen, Quan Dong; Agrawal, Anant

2014-02-01

 
 
 
 
241

Imaging pancreatobiliary ductal system with optical coherence tomography: A review  

Directory of Open Access Journals (Sweden)

Full Text Available An accurate, noninvasive and cost-effective method of in situ tissue evaluation during endoscopy would be highly advantageous for the detection of dysplasia or early cancer and for identifying different disease stages. Optical coherence tomography (OCT is a noninvasive, high-resolution (1-10 ?m emerging optical imaging method with potential for identifying microscopic subsurface features in the pancreatic and biliary ductal system. Tissue microstructure of pancreaticobiliary ductal system has been successfully imaged by inserting an OCT probe through a standard endoscope operative channel. High-resolution OCT images and the technique’s endoscopic compatibility have allowed for the microstructural diagnostic of the pancreatobiliary diseases. In this review, we discussed currently available pancreaticobiliary ductal imaging systems to assess the pancreatobiliary tissue microstructure and to evaluate varieties of pancreaticobiliary disorders and diseases. Results show that OCT can improve the quality of images of pancreatobiliary system during endoscopic retrograde cholangiopancheatography procedure, which may be important in distinguishing between the neoplastic and non-neoplastic lesions.

Mohammad S Mahmud

2013-01-01

242

Sound field reconstruction using acousto-optic tomography.  

Science.gov (United States)

When sound propagates through a medium, it results in pressure fluctuations that change the instantaneous density of the medium. Under such circumstances, the refractive index that characterizes the propagation of light is not constant, but influenced by the acoustic field. This kind of interaction is known as the acousto-optic effect. The formulation of this physical phenomenon into a mathematical problem can be described in terms of the Radon transform, which makes it possible to reconstruct an arbitrary sound field using tomography. The present work derives the fundamental equations governing the acousto-optic effect in air, and demonstrates that it can be measured with a laser Doppler vibrometer in the audible frequency range. The tomographic reconstruction is tested by means of computer simulations and measurements. The main features observed in the simulations are also recognized in the experimental results. The effectiveness of the tomographic reconstruction is further confirmed with representations of the very same sound field measured with a traditional microphone array. PMID:22559354

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

2012-05-01

243

Monte Carlo modeling of human tooth optical coherence tomography imaging  

International Nuclear Information System (INIS)

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

244

Light-shift tomography in an optical-dipole trap  

International Nuclear Information System (INIS)

Full text: We report on light-shift tomography of a cloud of 87Rb in a far-detuned optical-dipole trap. At this wavelength, the excited state of the cooling transition of 87Rb is strongly red-shifted, which enables us to perform energy-resolved imaging. We take advantage of this specific feature by using it in two different situations: mapping of the optical potential. Starting with a cold cloud with a smooth density profile, we switch on a trapping laser at 1565 nm, and immediately take an absorption image of the atoms in the presence of the trap. By scanning the probe laser frequency, we perform a mapping of the equal light-shift regions. Measurement of the atomic potential energy distribution. By counting the total number of atoms detected at a given probe detuning, we directly measure the number of atoms having a given potential energy in the trap. We follow the evolution of this atomic distribution for a trapped cloud during the free-evaporation process, starting from a strongly out-of-equilibrium situation and relaxing towards a thermal distribution. Using a spatially-varying light field, this technique could be used to address atoms situated in regions which size is smaller than the laser wavelength. (author)

245

Morphological phenotyping of mouse hearts using optical coherence tomography  

Science.gov (United States)

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.

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

2014-11-01

246

Multimodal full-field optical coherence tomography on biological tissue: toward all optical digital pathology  

Science.gov (United States)

Optical Coherence Tomography (OCT) is an efficient technique for in-depth optical biopsy of biological tissues, relying on interferometric selection of ballistic photons. Full-Field Optical Coherence Tomography (FF-OCT) is an alternative approach to Fourier-domain OCT (spectral or swept-source), allowing parallel acquisition of en-face optical sections. Using medium numerical aperture objective, it is possible to reach an isotropic resolution of about 1x1x1 ìm. After stitching a grid of acquired images, FF-OCT gives access to the architecture of the tissue, for both macroscopic and microscopic structures, in a non-invasive process, which makes the technique particularly suitable for applications in pathology. Here we report a multimodal approach to FF-OCT, combining two Full-Field techniques for collecting a backscattered endogeneous OCT image and a fluorescence exogeneous image in parallel. Considering pathological diagnosis of cancer, visualization of cell nuclei is of paramount importance. OCT images, even for the highest resolution, usually fail to identify individual nuclei due to the nature of the optical contrast used. We have built a multimodal optical microscope based on the combination of FF-OCT and Structured Illumination Microscopy (SIM). We used x30 immersion objectives, with a numerical aperture of 1.05, allowing for sub-micron transverse resolution. Fluorescent staining of nuclei was obtained using specific fluorescent dyes such as acridine orange. We present multimodal images of healthy and pathological skin tissue at various scales. This instrumental development paves the way for improvements of standard pathology procedures, as a faster, non sacrificial, operator independent digital optical method compared to frozen sections.

Harms, F.; Dalimier, E.; Vermeulen, P.; Fragola, A.; Boccara, A. C.

2012-03-01

247

Analysis of dental abfractions by optical coherence tomography  

Science.gov (United States)

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

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

2010-02-01

248

Root canal filling evaluation using optical coherence tomography  

Science.gov (United States)

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

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

2010-04-01

249

Towards spectral-domain optical coherence tomography on a silicon chip  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Optical coherence tomography (OCT) is a widely used optical imaging technology, particularly in the medical field, since it can provide non-invasive, sub-micrometer resolution diagnostic images of tissue. Current OCT systems contain optical fibers and free-space optical components which make these instruments bulky and costly. A significant decrease in the size and cost of an OCT system is possible through the use of integrated optics, allowing for compact and low-cost OCT systems, especially...

Akca, B. I.; Wo?rhoff, K.; Nguyen, V. D.; Kalkman, J.; Leeuwen, T. G.; Ridder, R. M.; Pollnau, M.

2011-01-01

250

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

Science.gov (United States)

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.

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

2011-03-01

251

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

Science.gov (United States)

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

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

2014-01-01

252

Compact MEMS-based adaptive optics: optical coherence tomography for clinical use  

Science.gov (United States)

We describe a compact MEMS-based adaptive optics (AO) optical coherence tomography (OCT) 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 limitations on current deformable mirror technologies, the amount of real-time ocular-aberration compensation is restricted and small in previous AO-OCT instruments. In this instrument, we incorporate an optical apparatus to correct the spectacle aberrations of the patients such as myopia, hyperopia and astigmatism. This eliminates the tedious process of using 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.

Chen, Diana C.; Olivier, Scot S.; Jones, Steven M.; Zawadzki, Robert J.; Evans, Julia W.; Choi, Stacey S.; Werner, John S.

2008-02-01

253

Development of an electro-optically tuned optical coherence tomography system for imaging dental lesions.  

Science.gov (United States)

A conventional optical coherence tomography (OCT) system was set up in-house to image early dental caries, identify gap formation in the bonding interface for restoration and secondary caries. Two-dimensional images of tooth samples was obtained and dental defect were identified. A novel electro-optic tuning system is proposed in order to improve scanning speed and to perform noiseless imaging. Preliminary studies were conducted with two crystals namely, LiNbO3 (Lithium Niobate) and KTP (Potassium Titanyl Phosphate) using a SLED source for OCT system and the simulated and experimental results were found to be qualitatively similar. The tuning range for LiNbO3 and KTP was found to be in the order of few micrometers whereas KTN (Potassium Tantalate Niobate) using the quadratic electro-optic effect is expected to show scanning range of tens of micrometers. KTN based hybrid scanning for dental caries imaging is also planned. PMID:25569924

Damodaran, Vani; Vasa, Nilesh J

2014-08-01

254

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

2008-02-04

255

Adaptive optics optical coherence tomography for in vivo mouse retinal imaging  

Science.gov (United States)

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.

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

2013-05-01

256

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

Science.gov (United States)

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

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

2014-02-01

257

Choroidal thinning in high myopia measured by optical coherence tomography  

Directory of Open Access Journals (Sweden)

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

Ikuno Y

2013-05-01

258

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

International Nuclear Information System (INIS)

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

259

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2010-01-01

260

Repeatability and reproducibility of manual choroidal volume measurements using enhanced depth imaging optical coherence tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This article reports highly reproducible and repeatable technique of manual choroidal volume measurements using the built-in automated retinal segmentation software of spectral-domain optical coherence tomography (SD-OCT) using enhanced depth imaging.

Barteselli, Giulio

2012-01-01

 
 
 
 
261

Technical Note: Wet validation of optical tomography for drinking water discolouration studies  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents a set of validation experiments for the reconstruction of a cross-sectional particle concentration field in a transparent pipe filled with a fluid using optical tomography.

R. Floris

2013-02-01

262

Technical Note: Wet validation of optical tomography for drinking water discolouration studies  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents a set of validation experiments for the reconstruction of a cross-sectional particle concentration field in a transparent pipe filled with a fluid using optical tomography.

R. Floris

2013-06-01

263

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

Background: The objective of our research was to use a noninvasive tomographic imagingtechnique with high spatial resolution (2-15 ?m) to characterize and monitorfluid flow and the microvasculature in highly scattering biological tissues atuser-specified discrete locations.Methods: The technique of optical Doppler tomography (ODT) combines laserDoppler flowmetry (LDF) with optical coherence tomography to obtainhigh-resolution tomographic velocity and structural images of static andmoving con...

Cheng-Jen Chang; Kuang-Hua Hou

2003-01-01

264

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2010-01-01

265

High-speed, Ultrahigh Resolution Optical Coherence Tomography of the Retina in Hunter Syndrome  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A 42-year-old man with Hunter syndrome developed bilateral visual field loss. Visual field testing demonstrated bilateral ring scotomata that corresponded to areas of thinning seen on standard resolution optical coherence tomography. High-speed, ultrahigh resolution optical coherence tomography, capable of 3.5-micron axial resolution, showed a loss of photoreceptors outside the fovea and cystoid spaces within the inner nuclear, ganglion cell, and outer nuclear layers. These results were consi...

Yoon, Michael K.; Chen, Royce W.; Hedges, Thomas R.; Srinivasan, Vivek J.; Gorczynska, Iwona; Fujimoto, James G.; Wojtkowski, Maciej; Schuman, Joel S.; Duker, Jay S.

2007-01-01

266

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

CERN Document Server

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.

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

2014-01-01

267

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

Science.gov (United States)

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

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

2014-02-01

268

Investigation of murine vasodynamics by Fourier domain optical coherence tomography  

Science.gov (United States)

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.

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

2007-07-01

269

Integral ceramic superstructure evaluation using time domain optical coherence tomography  

Science.gov (United States)

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.

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

2014-02-01

270

Shear wave elastography using phase sensitive optical coherence tomography  

Science.gov (United States)

Optical coherence tomography (OCT) provides high spatial resolution and sensitivity that are ideal for imaging the cornea and lens. Quantifying the biomechanical properties of these tissues could add clinically valuable information. Thus, we propose a dynamic elastography method combining OCT detection and a mechanical actuator to map the shear modulus of soft tissues. We used a piezoelectric actuator driven in the kHz range and we used phase-sensitive OCT (PhS-OCT) to track the resulting shear waves at an equivalent frame rate of 47 kHz. We mapped the shear wave speed of anesthetized mice cornea using monochromatic excitations. We found a significant difference between a group of knock-out (3.92 +/- 0.35 m/s, N=4) and wild-type mice (5.04 +/- 0.51 m/s, N=3). These preliminary results demonstrate the feasibility of using PhS-OCT to perform in vivo shear wave elastography of the cornea. We then implemented a shear pulse compression approach on ex vivo human cornea. For that purpose, frequency- modulated excitations were used and the resulting displacement field was digitally compressed in a short broadband pulse with a 7 dB gain in signal-to-noise ratio (SNR).

Song, Shaozhen; Huang, Zhihong; Nguyen, Thu-Mai; Wong, Emily Y.; Arnal, Bastien; O'Donnell, Matthew; Wang, Ruikang K.

2014-03-01

271

Volumetric full-range magnetomotive optical coherence tomography  

Science.gov (United States)

Magnetomotive optical coherence tomography (MM-OCT) can be utilized to spatially localize the presence of magnetic particles within tissues or organs. These magnetic particle-containing regions are detected by using the capability of OCT to measure small-scale displacements induced by the activation of an external electromagnet coil typically driven by a harmonic excitation signal. The constraints imposed by the scanning schemes employed and tissue viscoelastic properties limit the speed at which conventional MM-OCT data can be acquired. Realizing that electromagnet coils can be designed to exert MM force on relatively large tissue volumes (comparable or larger than typical OCT imaging fields of view), we show that an order-of-magnitude improvement in three-dimensional (3-D) MM-OCT imaging speed can be achieved by rapid acquisition of a volumetric scan during the activation of the coil. Furthermore, we show volumetric (3-D) MM-OCT imaging over a large imaging depth range by combining this volumetric scan scheme with full-range OCT. Results with tissue equivalent phantoms and a biological tissue are shown to demonstrate this technique.

Ahmad, Adeel; Kim, Jongsik; Shemonski, Nathan D.; Marjanovic, Marina; Boppart, Stephen A.

2014-12-01

272

Optical coherence tomography for imaging of skin and skin diseases  

DEFF Research Database (Denmark)

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

Mogensen, Mette; Thrane, Lars

2009-01-01

273

Dispersion phenomenon and a compensation method in optical coherence tomography  

Science.gov (United States)

The resolution of optical coherence tomography (OCT) depends on the spectral properties of the light sources used in OCT systems. The minimum distance that can be resolved by this technique is inversely proportional to the spectral width of the light source. Using broadband light sources, ultrahigh-resolution OCT can achieve axial image resolutions on the few micron scale. However, dispersion is known to increase the width of the envelope of the OCT signal and to reduce the resolution of OCT because different wavelengths of a broadband light source have different velocities in dispersive media. In the present paper, a super-luminescent diode (SLD) source is used to characterize the dispersion of different samples. The center wavelength of the light source is 845nm and spectral width is 26nm. A 30mm thick BK7 glass slab is tested. Based on the measured source spectrum, the broadened signals are calculated with the specific dispersion coefficients of different materials. The calculated signals are compared with the results measured in the experiments. A general numerical dispersion compensation method is present, which can both be applied in time domain and in frequency domain. Using this automatic iterative optimization method, the unbroadened signal can be regenerated with high resolution.

Tao, Tao; Liao, Ran; Lu, Jun; Zhu, Hongyi

2006-01-01

274

Imaging cutaneous T-Cell lymphoma with optical coherence tomography  

DEFF Research Database (Denmark)

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

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

2012-01-01

275

Optical coherence tomography as a guide for cochlear implant surgery?  

Science.gov (United States)

To assess the potential use of optical coherence tomography (OCT) in cochlear implant surgery, OCT was applied in human temporal bones before cochleostomy. The question was whether OCT might provide information about the cochlear topography, especially about the site of the scala tympani. OCT was carried out on human temporal bone preparations, in which the cochleostomy was performed leaving the membranous labyrinth and the fluid-filled inner ear intact. A specially equipped operating microscope with integrated OCT prototype was used. Spectral-domain (SD)-OCT was used for all investigations. On all scans, OCT supplied information about inner ear structures, such as scala tympani, scala vestibuli while the membranous labyrinth was still intact. In the fresh temporal bone the scala media, basilar membrane and the Reissner's membrane were identified. This OCT study clearly documents the possibility to identify inner ear structures, especially the scala tympani without opening its enveloping membranes. These findings may have an impact on cochlear implant surgery, especially as an orientation guide to localize the scala tympani precisely before opening the fluid filled inner ear.

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

2008-02-01

276

Orthogonal dispersive spectral-domain optical coherence tomography.  

Science.gov (United States)

Ultrahigh depth range spectral domain optical coherence tomography (SDOCT) can be realized based on the orthogonal dispersive spectrometer consisted by a high spectral resolution virtually-imaged phased array (VIPA) and a low spectral resolution grating. However, two critical issues result in the challenge of obtaining desirable one-dimensional (1-D) spectra from the recorded two-dimensional (2-D) orthogonal spectra for high-quality OD-SDOCT imaging. One is the wavenumber mapping errors and the other is the periodic intensity modulations. The paper proposes a method for desirable reconstruction of 1-D spectra from the recorded 2-D orthogonal spectra. A sample etalon with identical parameters to the dispersive VIPA is used to determine the free spectrum range (FSR) of the VIPA, and spectral phases from two reflecting mirrors are further applied for broadband wavenumber calibration. The cascading of column spectra are performed from interval of four lines of column spectra, and four records of cascaded 1-D spectra are obtained and then averaged to alleviate the periodic intensity modulations. Broadband 1-D spectra are thus reconstructed with an ultrahigh spectral resolution. To demonstrate the feasibility of the proposed method, three typical samples are imaged by the OD-SDOCT system. PMID:24787889

Bao, Wen; Ding, Zhihua; Li, Peng; Chen, Zhiyan; Shen, Yi; Wang, Chuan

2014-04-21

277

Optical coherence tomography-guided classification of epiretinal membranes.  

Science.gov (United States)

To study and classify epiretinal membranes (ERMs) based on spectral domain optical coherence tomography (SD-OCT) findings. One hundred and twelve patients with ERMs were examined clinically and underwent OCT examination. The anatomical structure of the macula and vitreoretinal interface was studied. ERMs were classified in two categories: A, with posterior vitreous detachment (PVD) (91 cases), and B, with the absence of PVD (21 cases). Category A was divided into two subcategories: A1, without contraction of the ERM (37 cases), and A2, with the presence of membrane contraction (54 cases). A2 was further subdivided into A2.1, with retinal folding (15 cases), A2.2, with edema (23 cases), A2.3, with cystoid macular edema (9 cases), and A2.4, with lamellar macular hole (7 cases). Category B was divided in two subcategories: B1, without vitreomacular traction (VMT) (4 cases), and B2, with the presence of VMT (17 cases). Category B2 was subdivided into B2.1, with edema (9 cases), B2.2, presenting retinal detachment (5 cases), and B2.3, with schisis (3 cases). OCT classification of ERMs provides useful information on the anatomical structure of the retina, and the accurate estimation of vitreoretinal interface. PMID:25038740

Konidaris, Vasileios; Androudi, Sofia; Alexandridis, Alexandros; Dastiridou, Anna; Brazitikos, Periklis

2014-07-20

278

Determination of dental decay rates with optical coherence tomography  

International Nuclear Information System (INIS)

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

279

Simultaneous dual-band optical coherence tomography for endoscopic applications  

Science.gov (United States)

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

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

2014-12-01

280

Optical coherence tomography: A new strategy to image planarian regeneration  

Science.gov (United States)

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, energy, and entropy) to compare the primitive and regenerated tissues. In the head and tail fragments, the signal attenuation rates of the regenerated fragments decreased from -0.2 dB/?m to -0.05 dB/?m, between Day 1 and Day 6, and then increased to -0.2 dB/?m on Day 14. The intensity ratios decreased to approximately 0.8 on Day 6, and increased to between 0.8 and 0.9 on Day 14. The texture parameters of contrast, correlation, and homogeneity exhibited trends similar to the signal attenuation rates and intensity ratios during the planarian regeneration. The proposed OCT parameters might provide biological information regarding cell apoptosis and the formation of a mass of new cells during planarian regeneration. Therefore, OCT imaging is a potentially effective method for planarian studies.

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

2014-09-01

 
 
 
 
281

Optical coherence tomography in the diagnosis of basal cell carcinoma.  

Science.gov (United States)

Since its introduction in dermatology in the late 1990s optical coherence tomography (OCT) has been used to study many skin diseases, in particular non-melanoma skin cancer and it s precursors. Special attention has been paid to superficial basal cell carcinoma (BCC), and a number of smaller observational studies have been published. The diagnostic criteria for BCC of these studies are systematically reviewed. A systemic review of English language studies was performed using PubMed, Google Scholar and Royal Danish Library, to search for primary papers on OCT and BCC. The references of retrieved papers were searched by hand for further relevant papers. A total of 39 papers were identified (search date: 2014-01-15). 22 were excluded because they did not meet the inclusion criteria, leaving 17 papers for analysis. In 100 % of the studies, rounded dark structures in the upper dermis surrounded by a hyperreflective halo possibly surrounded by a hyporeflective border and disruption of epidermal layering were described. In 53 % of the reports a hyporeflective lateral tumour border was described. A range of other features were mentioned in a minority of the studies. It is suggested that these diagnostic criteria could be characteristic for identifying BCC lesions using OCT. PMID:25223745

Hussain, Alia Arif; Themstrup, Lotte; Jemec, Gregor Borut Ernst

2015-01-01

282

Automated segmentation of intraretinal cystoid fluid in optical coherence tomography.  

Science.gov (United States)

Cystoid macular edema (CME) is observed in a variety of ocular disorders and is strongly associated with vision loss. Optical coherence tomography (OCT) provides excellent visualization of cystoid fluid, and can assist clinicians in monitoring the progression of CME. Quantitative tools for assessing CME may lead to better metrics for choosing treatment protocols. To address this need, this paper presents a fully automated retinal cyst segmentation technique for OCT image stacks acquired from a commercial scanner. The proposed method includes a computationally fast bilateral filter for speckle denoising while maintaining CME boundaries. The proposed technique was evaluated in images from 16 patients with vitreoretinal disease and three controls. The average sensitivity and specificity for the classification of cystoid regions in CME patients were found to be 91% and 96%, respectively, and the retinal volume occupied by cystoid fluid obtained by the algorithm was found to be accurate within a mean and median volume fraction of 1.9% and 0.8%, respectively. PMID:22271827

Wilkins, Gary R; Houghton, Odette M; Oldenburg, Amy L

2012-04-01

283

Ultrahigh speed endoscopic optical coherence tomography for gastroenterology.  

Science.gov (United States)

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

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

2014-12-01

284

Comparison of optical coherence tomography imaging of cataracts with histopathology  

Science.gov (United States)

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.

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

1999-10-01

285

Evaluation of fingerprint deformation using optical coherence tomography  

Science.gov (United States)

Biometric identification systems have important applications to privacy and security. The most widely used of these, print identification, is based on imaging patterns present in the fingers, hands and feet that are formed by the ridges, valleys and pores of the skin. Most modern print sensors acquire images of the finger when pressed against a sensor surface. Unfortunately, this pressure may result in deformations, characterized by changes in the sizes and relative distances of the print patterns, and such changes have been shown to negatively affect the performance of fingerprint identification algorithms. Optical coherence tomography (OCT) is a novel imaging technique that is capable of imaging the subsurface of biological tissue. Hence, OCT may be used to obtain images of subdermal skin structures from which one can extract an internal fingerprint. The internal fingerprint is very similar in structure to the commonly used external fingerprint and is of increasing interest in investigations of identify fraud. We proposed and tested metrics based on measurements calculated from external and internal fingerprints to evaluate the amount of deformation of the skin. Such metrics were used to test hypotheses about the differences of deformation between the internal and external images, variations with the type of finger and location inside the fingerprint.

Gutierrez da Costa, Henrique S.; Maxey, Jessica R.; Silva, Luciano; Ellerbee, Audrey K.

2014-02-01

286

Optical Coherence Tomography: Clinical Applications in Medical Practice  

Directory of Open Access Journals (Sweden)

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

Abdullah Al-Mujaini

2013-03-01

287

Optical coherence tomography and confocal microscopy investigations of dental prostheses  

Science.gov (United States)

Dental prostheses are very complex systems, heterogenous in structure, made up from various materials, with different physical properties. An essential question mark is on the physical, chemical and mechanical compatibility between these materials. They have to satisfy high stress requirements as well as esthetic challenges. The masticatory stress may induce fractures of the prostheses, which may be triggered by initial materials defects or by alterations of the technological process. The failures of dental prostheses lead to functional, esthetic and phonetic disturbances which finally render the prosthetic treatment inefficient. The purpose of this study is to evaluate the capability of en-face optical coherence tomography as a possible non-invasive high resolution method in supplying the necessary information on the material defects of dental prostheses and microleakage at prosthetic interfaces. C-scan and B-scan OCT images as well as confocal images are acquired from a large range of samples. Gaps between the dental interfaces and material defects are clearly exposed. We conclude that OCT can successfully be used as a noninvasive analysis method.

Negrutiu, Meda L.; Sinescu, Cosmin; Hughes, Michael; Bradu, Adrian; Rominu, Mihai; Todea, Carmen; Dobre, George; Podoleanu, Adrian

2008-09-01

288

Wavelet domain compounding for speckle reduction in optical coherence tomography.  

Science.gov (United States)

Visibility of optical coherence tomography (OCT) images can be severely degraded by speckle noise. A computationally efficient despeckling approach that strongly reduces the speckle noise is reported. It is based on discrete wavelet transform (DWT), but eliminates the conventional process of threshold estimation. By decomposing an image into different levels, a set of sub-band images are generated, where speckle noise is additive. These sub-band images can be compounded to suppress the additive speckle noise, as DWT coefficients resulting from speckle noise tend to be approximately decorrelated. The final despeckled image is reconstructed by taking the inverse wavelet transform of the new compounded sub-band images. The performance of speckle reduction and edge preservation is controlled by a single parameter: the level of wavelet decomposition. The proposed technique is applied to intravascular OCT imaging of porcine carotid arterial wall and ophthalmic OCT images. Results demonstrate the effectiveness of this technique for speckle noise reduction and simultaneous edge preservation. The presented method is fast and easy to implement and to improve the quality of OCT images. PMID:24002189

Xu, Jianbing; Ou, Haiyan; Sun, Cuiru; Chui, Po Ching; Yang, Victor X D; Lam, Edmund Y; Wong, Kenneth K Y

2013-09-01

289

Retinal and choroidal intravascular spectral-domain optical coherence tomography  

DEFF Research Database (Denmark)

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

Willerslev, Anne; Li, Xiao Q

2013-01-01

290

Application of anterior segment optical coherence tomography in glaucoma.  

Science.gov (United States)

Optical coherence tomography (OCT) is a cross-sectional, three-dimensional, high-resolution imaging modality that uses low coherence interferometry to achieve axial resolution in the range of 3-20 ?m. Two OCT platforms have been developed: time domain (TD-OCT) and spectral (or Fourier) domain (SD/FD-OCT). Visante anterior segment OCT (Carl Zeiss Meditec) is a TD-OCT widely used for anterior segment imaging. The SD-OCT systems with both posterior and anterior segment imaging capabilities include the RTVue, iVue (Optovue), the Cirrus (Carl Zeiss Meditec), and the Spectralis (Heidelberg Engineering, Inc.). Each of the SD-OCTs has a wavelength in the range of 820-879 nm. Anterior segment OCT is a non-contact method providing high resolution tomographic cross-sectional imaging of anterior segment structures. Anterior segment OCT provides qualitative and quantitative assessment of the anterior segment structures important to the pathogenesis and the anatomical variations of glaucoma, and the approach to and success of treatment. We summarize the clinical applications of anterior segment OCT in glaucoma. PMID:24138894

Sharma, Reetika; Sharma, Ajay; Arora, Tarun; Sharma, Sourabh; Sobti, Amit; Jha, Bhaskar; Chaturvedi, Neha; Dada, Tanuj

2014-01-01

291

The potential of optical coherence tomography for diagnosing meniscal pathology  

International Nuclear Information System (INIS)

Meniscal tears are often associated with anterior cruciate ligament (ACL) injury and may lead to pain and discomfort in humans. Maximal preservation of meniscal tissue is highly desirable to mitigate the progression of osteoarthritis. Guidelines of which meniscal tears are amenable to repair and what part of damaged tissues should be removed are elusive and lacking consensus. Images of microstructural changes in meniscus would potentially guide the surgeons to manage the meniscal tears better, but the resolution of current diagnostic techniques is limited for this application. In this study, we demonstrated the feasibility of using optical coherence tomography (OCT) for the diagnosis of meniscal pathology. Torn medial menisci were collected from dogs with ACL insufficiency. The torn meniscus was divided into three tissue samples and scanned by OCT and scanning electron microscopy (SEM). OCT and SEM images of torn menisci were compared. Each sample was evaluated for gross and microstructural abnormalities and reduction or loss of birefringence from the OCT images. The abnormalities detected with OCT were described for each type of tear. OCT holds promise in non-destructive and fast assessment of microstructural changes and tissue birefringence of meniscal tears. Future development of intraoperative OCT may help surgeons in the decision making of meniscal treatment

292

Automated segmentation of tissue structures in optical coherence tomography data  

Science.gov (United States)

Segmentation of optical coherence tomography (OCT) images provides useful information, especially in medical imaging applications. Because OCT images are subject to speckle noise, the identification of structures is complicated. Addressing this issue, two methods for the automated segmentation of arbitrary structures in OCT images are proposed. The methods perform a seeded region growing, applying a model-based analysis of OCT A-scans for the seed's acquisition. The segmentation therefore avoids any user-intervention dependency. The first region-growing algorithm uses an adaptive neighborhood homogeneity criterion based on a model of an OCT intensity course in tissue and a model of speckle noise corruption. It can be applied to an unfiltered OCT image. The second performs region growing on a filtered OCT image applying the local median as a measure for homogeneity in the region. Performance is compared through the quantitative evaluation of artificial data, showing the capabilities of both in terms of structures detected and leakage. The proposed methods were tested on real OCT data in different scenarios and showed promising results for their application in OCT imaging.

Gasca, Fernando; Ramrath, Lukas; Huettmann, Gereon; Schweikard, Achim

2009-05-01

293

Adaptive compressed sensing for spectral-domain optical coherence tomography  

Science.gov (United States)

Spectral-domain optical coherence tomography (SD-OCT) is a non-contact and non-invasive method for measuring the change of biological tissues caused by pathological changes of body. CCD with huge number of pixels is usually used in SD-OCT to increase the detecting depth, thus enhancing the hardness of data transmission and storage. The usage of compressed sensing (CS) in SD-OCT is able to reduce the trouble of large data transfer and storage, thus eliminating the complexity of processing system. The traditional CS uses the same sampling model for SD-OCT images of different tissue, leading to reconstruction images with different quality. We proposed a CS with adaptive sampling model. The new model is based on uniform sampling model, and the interference spectral of SD-OCT is considered to adjust the local sampling ratio. Compared with traditional CS, adaptive CS can modify the sampling model for images of different tissue according to different interference spectral, getting reconstruction images with high quality without changing sampling model.

Wang, Yi; Chen, Xiaodong; Wang, Ting; Li, Hongxiao; Yu, Daoyin

2014-03-01

294

Spectral domain optical coherence tomography imaging with an integrated optics spectrometer  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We designed and fabricated an arrayed-waveguide grating (AWG) in silicon oxynitride as a spectrometer for spectral domain optical coherence tomography (SD-OCT). The AWG has a footprint of only 3.0 cm x 2.5 cm, operates at a center wavelength of 1300 nm, and has 78 nm free spectral range. OCT measurements are performed that demonstrate imaging up to a maximum depth of 1 mm with an axial resolution of 19 mu m, both in agreement with the AWG design parameters. Using the AWG spectrometer combined...

Nguyen, V. D.; Akca, B. I.; Wo?rhoff, K.; Ridder, R. M.; Pollnau, M.; Leeuwen, T. G.; Kalkman, J.

2011-01-01

295

Three dimensional image reconstruction based on a wide-field optical coherence tomography system  

Science.gov (United States)

Wide-field optical coherence tomography has a promising application for its high scanning rate and resolution. The principle of a wide-field optical coherence tomography system is described, and 2D images of glass slides are reconstructed using eight-stepped phase-shifting method in the system. Using VC6.0 and OpenGL programming, 3D images are reconstructed based on the Marching Cube algorithm with 2D image sequences. The experimental results show that the depth detection and three-dimensional tomography for translucent materials could be implemented efficiently in the WFOCT system.

Feng, Yinqi; Feng, Shengtong; Zhang, Min; Hao, Junjun

2014-07-01

296

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

1997-01-01

297

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2011-01-01

298

Common-Path Optical Coherence Tomography for Biomedical Imaging and Sensing  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2010-01-01

299

Phosphorylated Neurofilament Heavy Chain Correlations to Visual Function, Optical Coherence Tomography, and Treatment  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Objective. To correlate visual and neurologic clinical scores and treatment of optic neuritis and multiple sclerosis (MS) patients with assays of serum phosphorylated neurofilament heavy chain (pNF-H) and optical coherence tomography (OCT) measurements of axonal loss. Design/Methods. The Optic Neuritis Treatment Trial (ONTT) randomized 457 patients with acute optic neuritis to intravenous methylprednisolone (IVMP) followed by oral prednisone, oral prednisone or placeb...

John Guy; Randy Kardon; Gerry Shaw; Cui Yang; Joshua Pasol; William Feuer

2010-01-01

300

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

Science.gov (United States)

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.

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

2014-02-01

 
 
 
 
301

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

Directory of Open Access Journals (Sweden)

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

Jeehyun Kim

2011-10-01

302

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

Science.gov (United States)

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

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

2011-01-01

303

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

International Nuclear Information System (INIS)

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

304

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

Directory of Open Access Journals (Sweden)

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

C. Torrón-Fernández-Blanco

2007-04-01

305

Common path optical coherence tomography based on fiber bundle imager  

Science.gov (United States)

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

Han, Jae Ho

306

Development and Application of Multifunctional Optical Coherence Tomography  

Science.gov (United States)

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,

Zhi, Zhongwei

307

Evaluation of caries-affected dentin with optical coherence tomography  

Directory of Open Access Journals (Sweden)

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

Cynthia Soares de Azevedo

2011-10-01

308

Multiple step algorithms for fluorescence -enhanced diffuse optical tomography  

International Nuclear Information System (INIS)

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

309

Performance comparison of different metrics for spectroscopic optical coherence tomography  

Science.gov (United States)

When light interacts with a scattering medium, the spectrum of the incident light undergoes changes that are dependent on the size of the scatterers in the medium. Spectroscopic Optical Coherence Tomography (S-OCT) is a method that can be used to ascertain the resulting spatially-dependent spectral information. In fact, S-OCT is sensitive to structures that are below the spatial resolution of the system, making S-OCT a promising tool for diagnosing many diseases and biological processes that change tissue structure, like cancer. The most important signal processing steps for S-OCT are the depth-resolved spectral analysis and the calculation of a spectroscopic metric. While the former calculates the spectra from the raw OCT data, the latter analyzes the information content of the processed depth-resolved spectra. We combine the Dual Window spectral analysis with different spectroscopic metrics, which are used as an input to colorize intensity based images. These metrics include the spectral center of mass method, principal component (PCA) and phasor analysis. To compare the performance of the metrics in a quantitative manner, we use a cluster algorithm to calculate efficiencies for all methods. For this purpose we use phantom samples which contain areas of microspheres of different sizes. Our results demonstrate that PCA and phasor analysis have the highest efficiencies, and can clearly separate these areas. Finally we will present data from cartilage tissue under static load in vitro. These preliminary results show that S-OCT can generate additional contrast in biological tissue in comparison to the pure intensity based images.

Jaedicke, Volker; Agcaer, Semih; Robles, Francisco E.; Steinert, Marian; Jones, David; Goebel, Sebastian; Gerhardt, Nils C.; Welp, Hubert; Hofmann, Martin R.

2014-03-01

310

Evaluation of caries-affected dentin with optical coherence tomography  

Scientific Electronic Library Online (English)

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

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

2011-10-01

311

Retinal neurodegeneration on optical coherence tomography and cerebral atrophy.  

Science.gov (United States)

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

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

312

Validation of optical coherence tomography in vivo using cryostat histology  

International Nuclear Information System (INIS)

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

313

Multiscale imaging of human thyroid pathologies using integrated Optical Coherence Tomography (OCT) and Optical Coherence Microscopy (OCM)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We evaluate the feasibility of optical coherence tomography (OCT) and optical coherence microscopy (OCM) for imaging of benign and malignant thyroid lesions ex vivo using intrinsic optical contrast. Thirty four thyroid gland specimens were imaged from 17 patients, covering a spectrum of pathology, ranging from normal thyroid to neoplasia and benign disease. The integrated OCT and OCM imaging system allows seamlessly switching between low and high magnifications, in a way similar to traditiona...

Zhou, Chao; Wong, Yihong; Aguirre, Aaron Dominic; Tsai, Tsung-han; Cohen, David W.; Connolly, James L.; Fujimoto, James G.

2010-01-01

314

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2005-01-01

315

Fibreoptic methods of cross-polarisation optical coherence tomography for endoscopic studies  

International Nuclear Information System (INIS)

Two systems of cross-polarisation optical coherence tomography based on polarisation-maintaining and polarisation non-maintaining fibres intended for in vivo endoscopic studies of biological objects are described. The sensitivities of the systems detecting scattered light with the initial and orthogonal polarisations in media with local microscopic optical anisotropic inhomogeneities are compared. (biophotonics)

316

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

International Nuclear Information System (INIS)

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

317

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

International Nuclear Information System (INIS)

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

318

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

International Nuclear Information System (INIS)

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

319

Three-dimensional motion correction using speckle and phase for in vivo computed optical interferometric tomography.  

Science.gov (United States)

Over the years, many computed optical interferometric techniques have been developed to perform high-resolution volumetric tomography. By utilizing the phase and amplitude information provided with interferometric detection, post-acquisition corrections for defocus and optical aberrations can be performed. The introduction of the phase, though, can dramatically increase the sensitivity to motion (most prominently along the optical axis). In this paper, we present two algorithms which, together, can correct for motion in all three dimensions with enough accuracy for defocus and aberration correction in computed optical interferometric tomography. The first algorithm utilizes phase differences within the acquired data to correct for motion along the optical axis. The second algorithm utilizes the addition of a speckle tracking system using temporally- and spatially-coherent illumination to measure motion orthogonal to the optical axis. The use of coherent illumination allows for high-contrast speckle patterns even when imaging apparently uniform samples or when highly aberrated beams cannot be avoided. PMID:25574426

Shemonski, Nathan D; Ahn, Shawn S; Liu, Yuan-Zhi; South, Fredrick A; Carney, P Scott; Boppart, Stephen A

2014-12-01

320

Quantitative evaluation of systematic imaging error due to uncertainty in tissue optical properties in high-density diffuse optical tomography  

Science.gov (United States)

In MRI-guided diffuse optical tomography of the human brain function, three-dimensional anatomical head model consisting of up to five segmented tissue types can be specified. With disregard to misclassification between different tissues, uncertainty in the optical properties of each tissue type becomes the dominant cause of systematic error in image reconstruction. In this study we present a quantitative evaluation of image resolution dependence due to such uncertainty. Our results show that given a head model which provides a realistic description of its tissue optical property distribution, high-density diffuse optical tomography with cortically constrained image reconstruction are capable of detecting focal activation up to 21.81 mm below the human scalp at an imaging quality better than or equal to 1.0 cm in localization error and 1.0 cm3 in FVHM with a tolerance of uncertainty in tissue optical properties between +15% and -20%.

Zhan, Yuxuan; Eggebrecht, Adam; Dehghani, Hamid; Culver, Joseph

2011-02-01

 
 
 
 
321

Integrated Optical Coherence Tomography and Microscopy for Ex Vivo Multiscale Evaluation of Human Breast Tissues  

Digital Repository Infrastructure Vision for European Research (DRIVER)

3D tissue imaging methods are expected to improve surgical management of cancer. In this study, we examined the feasibility of two 3D imaging technologies, optical coherence tomography (OCT) and optical coherence microscopy (OCM), to view human breast specimens based on intrinsic optical contrast. Specifically, we imaged 44 ex vivo breast specimens including 34 benign and 10 malignant lesions with an integrated OCT and OCM system developed in our laboratory. The system enabled 4 ?m axial res...

Zhou, Chao; Cohen, David W.; Wang, Yihong; Lee, Hsiang-chieh; Mondelblatt, Amy E.; Tsai, Tsung-han; Aguirre, Aaron D.; Fujimoto, James G.; Connolly, James L.

2010-01-01

322

Time-domain diffuse optical tomography processing by using the Mellin-Laplace transform.  

Science.gov (United States)

We investigate the use of the Mellin-Laplace transform for reconstructing optical parameters from time-resolved optical tomography in diffusive media. We present here its definition, its mathematical properties, and its sensitivity to variations of optical properties. The method was validated on two-dimensional reconstructions from simulation in the reflection geometry. We conclude that reconstructions based on the Mellin-Laplace transform are more robust to noise than the methods using first moments. PMID:22945142

Hervé, Lionel; Puszka, Agathe; Planat-Chrétien, Anne; Dinten, Jean-Marc

2012-09-01

323

Born Normalization for Fluorescence Optical Projection Tomography for Whole Heart Imaging  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

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

2009-01-01

324

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

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

2012-01-01

325

Contrast enhanced high-resolution diffuse optical tomography of the human brain using ICG  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Non-invasive diffuse optical tomography (DOT) of the adult brain has recently been shown to improve the spatial resolution for functional brain imaging applications. Here we show that high-resolution (HR) DOT is also advantageous for clinical perfusion imaging using an optical contrast agent. We present the first HR-DOT results with a continuous wave near infrared spectroscopy setup using a dense grid of optical fibers and indocyanine green (ICG) as an exogenic contrast agent. We find an earl...

Habermehl, Christina; Schmitz, Christoph H.; Steinbrink, Jens

2011-01-01

326

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2012-01-01

327

Quantitative lateral and axial flow imaging with optical coherence microscopy and tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Optical coherence tomography (OCT) and optical coherence microscopy (OCM) allow the acquisition of quantitative three-dimensional axial flow by estimating the Doppler shift caused by moving scatterers. Measuring the velocity of red blood cells is currently the principal application of these methods. In many biological tissues, blood flow is often perpendicular to the optical axis, creating the need for a quantitative measurement of lateral flow. Previous work has shown that lateral flow can b...

Bouwens, Arno; Szlag, Daniel Pawel; Szkulmowski, Maciej; Bolmont, Tristan; Wojtkowski, Maciej; Lasser, Theo

2013-01-01

328

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

CERN Document Server

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.

Kushnir, O; Vlokh, R; Kukhtarev, N

2005-01-01

329

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

Directory of Open Access Journals (Sweden)

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.

Kushnir O.

2005-09-01

330

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

CERN Document Server

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.

2013-01-01

331

Optical scattering coefficient estimated by optical coherence tomography correlates with collagen content in ovarian tissue.  

Science.gov (United States)

Optical scattering coefficient from ex vivo unfixed normal and malignant ovarian tissue was quantitatively extracted by fitting optical coherence tomography (OCT) A-line signals to a single scattering model. 1097 average A-line measurements at a wavelength of 1310 nm were performed at 108 sites obtained from 18 ovaries. The average scattering coefficient obtained from the normal tissue group consisted of 833 measurements from 88 sites was 2.41 mm(-1) (± 0.59), while the average coefficient obtained from the malignant tissue group consisted of 264 measurements from 20 sites was 1.55 mm(-1) (± 0.46). The malignant ovarian tissue showed significant lower scattering than the normal group (p Red. The average collagen area fraction (CAF) obtained from the normal tissue group was 48.4% (± 12.3%), while the average CAF obtained from the malignant tissue group was 11.4% (± 4.7%). A statistical significance of the collagen content was found between the two groups (p < 0.001). These results demonstrated that quantitative measurements of optical scattering coefficient from OCT images could be a potential powerful method for ovarian cancer detection. PMID:21950907

Yang, Yi; Wang, Tianheng; Biswal, Nrusingh C; Wang, Xiaohong; Sanders, Melinda; Brewer, Molly; Zhu, Quing

2011-09-01

332

In vitro assessment of effects of hyperglycemia on the optical properties of blood during coagulation using optical coherence tomography.  

Science.gov (United States)

No published reports have demonstrated the capability of the optical coherence tomography technique for quantifying the optical coherence tomography signal slope, 1/e light penetration depth, and attenuation coefficient of hyperglycemic blood by an in vitro assessment. The purpose of this study was to investigate the effects of hyperglycemia on optical properties during in vitro blood coagulation by optical coherence tomography. Normal whole blood acted as the control group. After 1-h coagulation, the average optical coherence tomography signal slope decreased approximately 23.3 and 16.7 %, and the 1/e light penetration depths increased approximately 21.5 and 19.2 % for the control and hyperglycemic groups, respectively. It could be seen from the 1/e light penetration depth evolution curves that the blood coagulation time was about (425?±?19)?s for normal whole blood and (367?±?15)?s for the hyperglycemic blood. The coagulation time decreased 13.6 % for the hyperglycemic blood compared with that for normal whole blood. There was statistically significant difference in blood coagulation time between the hyperglycemic and normal whole blood (p?experiment was the first reported study of monitoring hyperglycemic blood coagulation using OCT. We conclude that OCT is potential technique to quantify and follow the liquid-gel transition of hyperglycemic blood coagulation. PMID:25380667

Liu, Ying; Wu, Guoyong; Wei, Huajiang; Guo, Zhouyi; Yang, Hongqin; He, Yonghong; Xie, Shusen; Zhang, Yuqing; Zhu, Zhenguo

2015-01-01

333

Patency of small laser iridotomy evaluated using anterior-segment optical coherence tomography  

Directory of Open Access Journals (Sweden)

Full Text Available Seigo Nakabayashi, Motofumi Kawai, Toru Yamaguchi, Akitoshi Yoshida Department of Ophthalmology, Asahikawa Medical University, Asahikawa, Japan Abstract: We report the case of a patient with recurrent acute angle-closure glaucoma who had undergone a previous laser iridotomy. Because the initial iridotomy was small, patency could not be determined by slit-lamp examination. Therefore, anterior-segment optical coherence tomography was used to evaluate the patency. Cross-sectional images showed the presence of a membrane with an anterior bowing configuration at the base of the iridotomy, suggesting that recurrent pupillary block was the causative mechanism. A repeat laser iridotomy was performed, with a resultant decrease in the intraocular pressure and widening of the anterior chamber angle. Anterior-segment optical coherence tomography may be helpful to confirm the status of a laser iridotomy, especially when the iridotomy is small. Keywords: anterior-segment optical coherence tomography, laser iridotomy, acute angle-closure glaucoma

Nakabayashi S

2014-03-01

334

Structural examination of easel paintings with optical coherence tomography.  

Science.gov (United States)

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

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

2010-06-15

335

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

Science.gov (United States)

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 internal structure of adult zebrafish without staining or clearing agents. This method extends the use of Optical Projection Tomography to optically diffusive samples yielding reconstructions with reduced artifacts, increased contrast and improved resolution with respect to those obtained with non-gated techniques. The paper shows that TGOPT is particularly suited for imaging the skeletal system and nervous structures of adult zebrafish. PMID:23185643

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

2012-01-01

336

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

International Nuclear Information System (INIS)

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

337

Combined application of optical methods to increase the information content of optical coherent tomography in diagnostics of neoplastic processes  

International Nuclear Information System (INIS)

A combined application of optical methods [optical coherent tomography (OCT), cross-polarisation optical coherent tomography, and fluorescence spectroscopy] is proposed for obtaining information on morphological and biochemical changes occurring in tissues in norm and pathology. It is shown that neoplastic and scar changes in esophagus can be distinguished using a combination of polarisation and standard OCT due to the difference between the depolarising properties of the tissues caused by the structural properties of collagenic fibres in stroma. It is shown that OCT combined with fluorescence spectroscopy with the use of 5-aminolevulinic acid is promising for determining the boundaries of carcinoma of the uterine cervix and vulva. It is found that the tumour boundary detected by optical methods coincides with the morphological boundary and extends beyond colposcopically determined boundary by about 2 mm. (laser biology and medicine)

338

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

Science.gov (United States)

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.

Chang, Y. J.

2015-01-01

339

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Mclellan, Gillian J.; Rasmussen, Carol A.

2012-01-01

340

Repeatability of in vivo 3D lamina cribrosa microarchitecture using adaptive optics spectral domain optical coherence tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We demonstrate the repeatability of lamina cribrosa (LC) microarchitecture for in vivo 3D optical coherence tomography (OCT) scans of healthy, glaucoma suspects, and glaucomatous eyes. Eyes underwent two scans using a prototype adaptive optics spectral domain OCT (AO-SDOCT) device from which LC microarchitecture was semi-automatically segmented. LC segmentations were used to quantify pore and beam structure through several global microarchitecture parameters. Repeatability of LC microarchitec...

Nadler, Zach; Wang, Bo; Wollstein, Gadi; Nevins, Jessica E.; Ishikawa, Hiroshi; Bilonick, Richard; Kagemann, Larry; Sigal, Ian A.; Ferguson, R. Daniel; Patel, Ankit; Hammer, Daniel X.; Schuman, Joel S.

2014-01-01

 
 
 
 
341

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2011-01-01

342

Power-efficient Fourier domain optical coherence tomography setup for selection in the optical path difference sign using Talbot bands.  

Science.gov (United States)

A power-efficient Fourier domain optical coherence tomography fiber system is presented free of mirror terms. The object and reference beams from the interferometer are spatially separated to illuminate different parts of the diffraction grating in the spectrometer according to a method inspired from the use of Talbot bands. In this way, the system is made sensitive to only one sign of the optical path difference in the interferometer. PMID:17700765

Podoleanu, Adrian; Woods, Daniel

2007-08-15

343

Three-dimensional imaging of whole rodent organs using optical computed and emission tomography.  

Science.gov (United States)

We explore the potential of optical computed tomography (optical-CT) and optical emission computed tomography (optical-ECT) in a new area-whole organ imaging. The techniques are implemented on an in-house prototype benchtop system with improved image quality and the capacity to image larger samples (up to 3 cm) than previous systems based on stereo microscopes. Imaging performance tests confirm high geometrical accuracy, accurate relative measurement of linear attenuation coefficients, and the ability to image features at the 50-microm level. Optical labeling of organ microvasculature was achieved using two stains deposited via natural in vivo circulatory processes: a passive absorbing ink-based stain and an active fluorescin FITC-lectin conjugate. The lectin protein binds to the endothelial lining, and FITC fluorescense enables optical-ECT imaging. Three-dimensional (3-D) optical-CT images have been acquired of a normal rat heart and left lung and a mouse right lung showing exquisite detail of the functional vasculature and relative perfusion distribution. Coregistered optical-ECT images were also acquired of the mouse lung and kidney. Histological sections confirmed effective labeling of microvasculature throughout the organs. The advantages of optical-CT and optical-ECT include the potential for a unique combination of high resolution and high contrast and compatibility with a wide variety of optical probes, including gene expression labeling fluorescent reporter proteins. PMID:17343484

Oldham, Mark; Sakhalkar, Harshad; Wang, Ying Min; Guo, Pengyi; Oliver, Tim; Bentley, Rex; Vujaskovic, Zeljko; Dewhirst, Mark

2007-01-01

344

Tomography  

International Nuclear Information System (INIS)

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

345

Adaptive optics spectral domain optical coherence tomography with one-micrometer light source  

Science.gov (United States)

Adaptive optics spectral domain optical coherence tomography (AO SD-OCT) has provided three-dimensional high isotropic resolution retinal images in vivo. In order to enhance the image quality of deep region of the eye, the alternative wavelength of 1-?m has been used for ophthalmic OCT. This study aims to develop AO SD-OCT with one-micrometer probe and demonstrated high penetration and high resolution retinal imaging. A broadband 1-?m SLD light source (Suplerlum) have the center wavelength of 1.03 ?m and the spectral bandwidth of 106 nm. Axial scans were obtained by an InGaAs line scan camera with the speed of 47,000 Hz. The aberrations of the system and the eye were measured by Shack-Hartmann wavefront sensor (HASO32, Imagine Eyes, France; corrected by a single deformable mirror (Mirao52, Imagine Eyes). The AO closed loop was working with the iteration frequency of 7 Hz. The residual root mean square (RMS) wavefront error was typically reduced to 0.1 ?m. Seven eyes of 7 normal subjects were examined. The signal gain was found for all subjects with AO. The waving interface of nerve fiber layer and ganglion cell layer, the interface between ganglion cell layer and inner plexiform layer and choroid-sclera interface were observed. AO SD-OCT with one-micrometer probe may be useful not only for the investigation of photoreceptors but also nerve fiber abnormalities.

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

2010-02-01

346

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

Science.gov (United States)

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.

Sudo, Kenta; Cense, Barry

2013-03-01

347

Theoretical study of acousto-optical coherence tomography using random phase jumps on ultrasound and light.  

Science.gov (United States)

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. PMID:21734743

Lesaffre, M; Farahi, S; Boccara, A C; Ramaz, F; Gross, M

2011-07-01

348

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

CERN Document Server

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...

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

2012-01-01

349

Stability in computed optical interferometric tomography (Part II): in vivo stability assessment.  

Science.gov (United States)

Stability is of utmost importance to a wide range of phase-sensitive processing techniques. In Doppler optical coherence tomography and optical coherence elastography, in addition to defocus and aberration correction techniques such as interferometric synthetic aperture microscopy and computational/digital adaptive optics, a precise understanding of the system and sample stability helps to guide the system design and choice of imaging parameters. This article focuses on methods to accurately and quantitatively measure the stability of an imaging configuration in vivo. These methods are capable of partially decoupling axial from transverse motion and are compared against the stability requirements for computed optical interferometric tomography laid out in the first part of this article. PMID:25321016

Shemonski, Nathan D; Ahmad, Adeel; Adie, Steven G; Liu, Yuan-Zhi; South, Fredrick A; Carney, P Scott; Boppart, Stephen A

2014-08-11

350

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

International Nuclear Information System (INIS)

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

351

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

DEFF Research Database (Denmark)

An advanced novel Monte Carlo simulation model of the detection process of an optical coherence tomography (OCT) system is presented. For the first time it is shown analytically that the applicability of the incoherent Monte Carlo approach to model the heterodyne detection process of an OCT system is firmly justified. This is obtained by calculating the heterodyne mixing of the reference and sample beams in a plane conjugate to the discontinuity in the sample probed by the system. Using this approach, a novel expression for the OCT signal is derived, which only depends uopon the intensity distribution of the light from the sample and the reference beam. To adequately estimate the intensity distributions, a novel method of modeling a focused Gaussian beam using Monte Carlo simulation is developed. This method is then combined with the derived expression for the OCT signal into a new Monte Carlo model of the OCT signal. The OCT signal from a scattering medium are obtained for several beam and sample geometries using the new Monte Carlo model, and when comparing to results of an analytical model based on the extended Huygens-Fresnel principle excellent agreement is obtained. With the greater flexibility of Monte Carlo simulations, this new model is demonstrated to be excellent as a numerical phantom, i.e., as a substitute for otherwise difficult experiments. Finally, a new model of the signal-to-noise ratio (SNR) of an OCT system with optical amplification of the light reflected from the sample is derived, and discussed. Using this model, the conclusion is reached that an optical amplifier will enable substantial improvement of the SNR for OCT systems dominated by receiver noise. Receiver noise is of practical concern because of the (often) limited irradiance of suitable optical sources for OCT, and high insertion loss of the fast optical delay-line scanners that are necessary for fast imaging. Correspondingly, an increase in penetration depth of about 30-100% is demonstrated for OCT imaging in skin based on resultsobtained with the new Monte Carlo model. Accordingly, the two new models are demonstrated as valuable tools for future development and optimization of OCT systems to extend the applications of the system in biomedicine.

Tycho, Andreas

2002-01-01

352

Size of the optic nerve in computed tomography  

International Nuclear Information System (INIS)

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

353

Effect of multimodal coupling in imaging micro-endoscopic fiber bundle on optical coherence tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The effect of higher order modes in fiber bundle imager-based optical coherence tomography (OCT) has been theoretically modeled using coupled fiber mode analysis ignoring the polarization and core size variation in order to visualize the pure effect of multimodal coupling of the imaging bundle. In this model, the optical imaging fiber couples several higher order modes in addition to the fundamental one due to its high numerical aperture for achieving light confinement to the single core pixe...

Han, Jae-ho; Kang, Jin U.

2012-01-01

354

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2012-01-01

355

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Patil, C. A.; Kalkman, J.; Faber, D. J.; Nyman, J. S.; Leeuwen, T. G.; Mahadevan-jansen, A.

2011-01-01

356

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2012-01-01

357

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2005-01-01

358

Endoscopic Functional Fourier Domain Common Path Optical Coherence Tomography for Microsurgery  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2010-01-01

359

Combined Raman spectroscopy and optical coherence tomography device for tissue characterization  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2008-01-01

360

Frequency–Domain Measurement of Neuronal Activity using Dynamic Optical Coherence Tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We report preliminary results on high-resolution in vivo imaging of fast intrinsic optical signals of neuronal activity in the frequency domain. An optical coherence tomography (OCT) system was used for dynamic imaging of the cross section of rodent somatosensory cortex at 250 frame/s. Neurons in the cortex were excited by contralateral forepaw stimulation, and the ipsilateral forepaw was stimulated as a control. Hemodynamic responses at the cortical surface, which were simultaneously measure...

Lee, Jonghwan; Boas, David A.

2012-01-01

 
 
 
 
361

Development of Optical Coherence Tomography for Quantitative Analysis of Cardiac Morphology  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Transgenic mouse models have been instrumental in the elucidation of the molecular mechanism behind many cardiac diseases such as Marfan syndrome. However, the small size of the murine heart has hampered the characterization of its cardiac morphology. In this project, we describe the development of a murine cardiac imaging modality using optical coherence tomography (OCT). After fixation and optical clearing, the hearts were imaged from multiple perspectives. These data sets were then correct...

Cua, Eunice Michelle Chua

2014-01-01

362

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 tom...

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

2014-01-01

363

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

Science.gov (United States)

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

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

2014-11-15

364

Coherent noise-free ophthalmic imaging by spectral optical coherence tomography  

International Nuclear Information System (INIS)

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

365

Optical coherence tomography (OCT) reveals depth-resolved dynamics during functional brain activation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Optical intrinsic signal imaging (OISI) provides two-dimensional, depth-integrated activation maps of brain activity. Optical coherence tomography (OCT) provides depth-resolved, cross-sectional images of functional brain activation. Co-registered OCT and OISI imaging was performed simultaneously on the rat somatosensory cortex through a thinned skull during forepaw electrical stimulation. Fractional signal change measurements made by OCT revealed a functional signal that correlates well with ...

Chen, Yu; Aguirre, Aaron D.; Ruvinskaya, Lana; Devor, Anna; Boas, David A.; Fujimoto, James G.

2008-01-01

366

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Sergiy Kharchenko; Jan Adamowicz; Maciej Wojtkowski; Tomasz Drewa

2013-01-01

367

Dual-wavelength photothermal optical coherence tomography for imaging microvasculature blood oxygen saturation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A swept-source dual-wavelength photothermal (DWP) optical coherence tomography (OCT) system is demonstrated for quantitative imaging of microvasculature oxygen saturation. DWP-OCT is capable of recording three-dimensional images of tissue and depth-resolved phase variation in response to photothermal excitation. A 1,064-nm OCT probe and 770-nm and 800-nm photothermal excitation beams are combined in a single-mode optical fiber to measure microvasculature hemoglobin oxygen saturation (SO2) lev...

Yin, Biwei; Kuranov, Roman V.; Mcelroy, Austin B.; Kazmi, Shams; Dunn, Andrew K.; Duong, Timothy Q.; Milner, Thomas E.

2013-01-01

368

Homodyne tomography characterization and nonlocality of a dual-mode optical qubit.  

Science.gov (United States)

A single photon, delocalized over two optical modes, is characterized by means of quantum homodyne tomography. The reconstructed four-dimensional density matrix extends over the entire Hilbert space and thus reveals, for the first time, complete information about the dual-rail optical quantum bit as a state of the electromagnetic field. The experimental data violate the Bell inequality albeit with a loophole similar to the detection loophole in photon counting experiments. PMID:15169401

Babichev, S A; Appel, J; Lvovsky, A I

2004-05-14

369

Ultrahigh-resolution optical coherence tomography with monochromatic and chromatic aberration correction  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We have developed an improved adaptive optics - optical coherence tomography (AO-OCT) system and evaluated its performance for in vivo imaging of normal and pathologic retina. The instrument provides unprecedented image quality at the retina with isotropic 3D resolution of 3.5 × 3.5 × 3.5 ?m3. Critical to the instrument's resolution is a customized achromatizing lens that corrects for the eye's longitudinal chromatic aberration and an ultra broadband light source (??=112nm ?0=?836 nm)...

Zawadzki, Robert J.; Cense, Barry; Zhang, Yan; Choi, Stacey S.; Miller, Donald T.; Werner, John S.

2008-01-01

370

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

CERN Document Server

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

Liu, Xue; Shahriar, M S

2010-01-01

371

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

Science.gov (United States)

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

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

2014-01-01

372

OPTICAL COHERENCE TOMOGRAPHY–GUIDED FACEDOWN POSITIONING FOR MACULAR HOLE SURGERY  

Science.gov (United States)

Purpose To use spectral domain optical coherence tomography–guided duration of facedown positioning to study anatomical macular hole closure rates. Methods Retrospective review of patients with macular holes undergoing 23-gauge pars plana vitrectomy and intraocular gas tamponade. Spectral domain optical coherence tomography imaging was done on postoperative Day 1. Patients remained facedown for 2 more days if the macular hole was closed or 6 more days facedown if the macular hole was open or indeterminate. Results There were 8 Stage 2, 12 Stage 3, and 12 Stage 4 macular holes. On postoperative Day 1, 24 holes were closed by spectral domain optical coherence tomography and instructed to remain facedown for two more days. Twenty-three of 24 holes remained closed during the postoperative period. Eight holes were open or indeterminate on postoperative Day 1 and remained facedown for 6 more days. Six of 8 holes (75%) were closed at their last follow-up. The overall closure rate was 29/32 (90.6%). Average follow-up was 334 days. Conclusion Confirming early closure of macular holes with spectral domain optical coherence tomography imaging can serve as an important guide to significantly shorten the duration of prone positioning while maintaining high closure rates. PMID:23343822

SHAH, SUMIT P.; MANJUNATH, VARSHA; ROGERS, ADAM H.; BAUMAL, CAROLINE R.; REICHEL, ELIAS; DUKER, JAY S.

2013-01-01

373

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

CERN Document Server

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.

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

2015-01-01

374

Reference optimization for a common-path optical coherence tomography probe using angle polishing  

Science.gov (United States)

In this study, we polished the tip of single mode fiber to an angle that optimizes the reference power of a common-path optical coherence tomography (CP OCT) system. OCT images obtained with optimized reference show significantly improved signal to noise ratio.

Liu, Xuan; Kang, Jin U.

2014-03-01

375

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Sand Trond; Wexler Alexandra; Elsås Tor B

2010-01-01

376

A rapid method of measuring dispersion in low coherence interferometry and optical coherence tomography systems  

International Nuclear Information System (INIS)

A method of using multiple spectral channels to measure dispersion mismatch in optical coherence tomography (OCT) and low coherence interferometry systems is presented. The method is tested on a time domain OCT system in comparison to the measurement of the auto-correlation profile. The method is quicker to implement and is more sensitive than the measurement of the auto-correlation profile

377

Single-shot speckle noise reduction by interleaved optical coherence tomography  

Science.gov (United States)

Speckle noise is one of the dominant factors that degrade image quality in optical coherence tomography (OCT). Here, we propose a new strategy, interleaved OCT (iOCT), for spatial compounding and angular compounding. We demonstrate the efficiency of compounding with iOCT to restrain speckle noise without compromising imaging speed in phantoms and tissue samples.

Duan, Lian; Lee, Hee Yoon; Lee, Gary; Agrawal, Monica; Smith, Gennifer T.; Ellerbee, Audrey K.

2014-12-01

378

One-step continuous synthesis of biocompatible gold nanorods for optical coherence tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present a novel one-step flow process to synthesize biocompatible gold nanorods with tunable absorption and biocompatible surface ligands. Photothermal optical coherence tomography (OCT) of human breast tissue is successfully demonstrated using tailored gold nanorods designed to have strong absorption in the near-infrared range.

Sebastia?n, Vi?ctor; Lee, Seung-kon; Zhou, Chao; Kraus, Martin F.; Fujimoto, James G.; Jensen, Klavs F.

2012-01-01

379

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

CERN Document Server

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.

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

2012-01-01

380

Optical Coherence Tomography and Biomolecular Imaging with Coherent Raman Scattering Microscopy  

DEFF Research Database (Denmark)

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

Andersson-Engels, Stefan; Andersen, Peter E.

2014-01-01

 
 
 
 
381

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

Science.gov (United States)

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

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

2014-08-01

382

Marginal adaptation of ceramic veneers investigated with en face optical coherence tomography  

Science.gov (United States)

The aim of this study was to analyze the quality of marginal adaptation and gap width of Empress veneers using en-face optical coherence tomography. The results prove the necessity of investigating the marginal adaptation after each veneer bonding process.

Sinescu, Cosmin; Negru?iu, Meda-Lavinia; Petrescu, Emanuela; Rominu, Mihai; Marcauteanu, Corina; Rominu, Roxana; Hughes, Michael; Bradu, Adrian; Dobre, George; Podoleanu, Adrian G.

2009-07-01

383

Adaptive wavelet analysis of optical coherent tomography data: Application in problems of diagnostics  

Science.gov (United States)

A method of adaptive wavelet analysis permitting one to set parameters of the wavelet transform based on principles of the optimization theory is proposed. Applying the method to optical coherent tomography data processing is considered. The efficiency of the proposed method for diagnosing functional disorders in the dynamics of cerebral vessels is illustrated.

Nazimov, A. I.; Pavlov, A. N.; Lychagov, V. V.; Semyachkina-Glushkovskaya, O. V.

2013-10-01

384

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

2008-02-08

385

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

Science.gov (United States)

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.

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

2013-03-01

386

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

Science.gov (United States)

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

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

2012-12-01

387

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

Science.gov (United States)

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

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

2010-02-01

388

Experimental study of z resolution in acousto-optical coherence tomography using random phase jumps on ultrasound and light  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 $z$ measureme...

Lesaffre, Max; Farahi, Salma; Ramaz, Franc?ois; Gross, Michel

2013-01-01

389

Adaptive optics parallel spectral domain optical coherence tomography for imaging the living retina  

Science.gov (United States)

Although optical coherence tomography (OCT) can axially resolve and detect reflections from individual cells, there are no reports of imaging cells in the living human retina using OCT. To supplement the axial resolution and sensitivity of OCT with the necessary lateral resolution and speed, we developed a novel spectral domain OCT (SD-OCT) camera based on a free-space parallel illumination architecture and equipped with adaptive optics (AO). Conventional flood illumination, also with AO, was integrated into the camera and provided confirmation of the focus position in the retina with an accuracy of ±10.3 ?m. Short bursts of narrow B-scans (100x560 ?m) of the living retina were subsequently acquired at 500 Hz during dynamic compensation (up to 14 Hz) that successfully corrected the most significant ocular aberrations across a dilated 6 mm pupil. Camera sensitivity (up to 94 dB) was sufficient for observing reflections from essentially all neural layers of the retina. Signal-to-noise of the detected reflection from the photoreceptor layer was highly sensitive to the level of cular aberrations and defocus with changes of 11.4 and 13.1 dB (single pass) observed when the ocular aberrations (astigmatism, 3rd order and higher) were corrected and when the focus was shifted by 200 ?m (0.54 diopters) in the retina, respectively. The 3D resolution of the B-scans (3.0x3.0x5.7 ?m) is the highest reported to date in the living human eye and was sufficient to observe the interface between the inner and outer segments of individual photoreceptor cells, resolved in both lateral and axial dimensions. However, high contrast speckle, which is intrinsic to OCT, was present throughout the AO parallel SD-OCT B-scans and obstructed correlating retinal reflections to cell-sized retinal structures.

Zhang, Yan; Rha, Jungtae; Jonnal, Ravi S.; Miller, Donald T.

2005-06-01

390

Adaptive optics optical coherence tomography for measuring phase and reflectance dynamics of photoreceptors  

Science.gov (United States)

Optical coherence tomography with adaptive optics (AO-OCT) is a noninvasive method for imaging the living retina at the microscopic level. We used AO-OCT technology to follow changes in cone photoreceptor outer segment (OS) length and reflectance. To substantially increase sensitivity of the length measurements, a novel phase retrieval technique was demonstrated, capable of detecting changes on a nanometer scale. We acquired volume videos of 0.65°x0.65° retinal patches at 1.5° temporal to the fovea over 75 and 105 minutes in two subjects. Volumes were dewarped and registered, after which the cone intensity, OS length, and referenced phase difference were tracked over time. The reflections from inner segment/OS junction (IS/OS) and posterior tips of OS (PT) showed significant intensity variations over time. In contrast, the OS length as measured from the intensity images did not change, indicative of a highly stable OS length at least down to the level of the system's axial resolution (3?m). Smaller axial changes, however, were detected with our phase retrieval technique. Specifically, the PT-IS/OS phase difference for the same cones showed significant variation, suggesting real sub-wavelength changes in OS length of 125+/-46 nm/hr for the 22 cones followed. We believe these length changes are due to the normal renewal process of the cone OS that elongate the OS at a rate of about 100 nm/hr. The phase difference measurements were strongly correlated among Alines within the same cone (0.65 radians standard deviation) corresponding to a length sensitivity of 31 nm, or ~100 times smaller than the axial resolution of our system.

Kocaoglu, Omer P.; Jonnal, Ravi S.; Lee, Sangyeol; Wang, Qiang; Liu, Zhuolin; Miller, Donald T.

2012-03-01

391

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

Energy Technology Data Exchange (ETDEWEB)

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.)

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

392

Edema macular quístico pseudofáquico: Detección mediante «optical coherence tomography» Pseudophakic cystoid macular edema: Assesment with optical coherence tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Objetivo: Detectar la incidencia de edema macular quístico (EMQ) tras cirugía de catarata tanto clínico como subclínico, mediante «ocular coherence tomography» (OCT) y comparar dicha incidencia entre un grupo de pacientes diabéticos y otro de no diabéticos. Material y métodos: Estudio prospectivo de 260 ojos intervenidos de forma consecutiva de catarata mediante facoemulsificación con implante de lente intraocular acrílica, desde septiembre de 2004 a marzo de 2005. Grupo A: 208 ojo...

Torro?n-ferna?ndez-blanco, C.; Ruiz-moreno, O.; Ferrer-novella, E.; Sa?nchez-cano, A.; Honrubia-lo?pez, F. M.

2006-01-01

393

Time-series estimation of biological factors in optical diffusion tomography  

International Nuclear Information System (INIS)

We apply state space estimation techniques to the time-varying reconstruction problem in optical tomography. We develop a stochastic model for describing the evolution of quasi-sinusoidal medical signals such as the heartbeat, assuming these are represented as a known frequency with randomly varying amplitude and phase. We use the extended Kalman filter in combination with spatial regularization techniques to reconstruct images from highly under-determined time-series data. This system also naturally segments activity belonging to different biological processes. We present reconstructions of simulated data and of real data recorded from the human motor cortex (Franceschini et al 2000 Optics Express 6 49-57). It is argued that the application of these time-series techniques improves both the fidelity and temporal resolution of reconstruction in optical tomography

394

Test target for characterizing 3D resolution of optical coherence tomography  

Science.gov (United States)

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.

Hu, Zhixiong; Hao, Bingtao; Liu, Wenli; Hong, Baoyu; Li, Jiao

2014-12-01

395

Nanoscale zoom tomography with hard x rays using Kirkpatrick-Baez optics  

International Nuclear Information System (INIS)

To overcome the limitations in terms of spatial resolution and field of view of existing tomography techniques, a hard x-ray projection microscope is realized based on the sub-100-nm focus produced by Kirkpatrick-Baez optics. The sample is set at a small distance downstream of the focus and Fresnel diffraction patterns with variable magnification are recorded on a medium-resolution detector. While the approach requires a specific phase retrieval procedure and correction for mirror imperfections, it allows zooming nondestructively into bulky samples. Quantitative three-dimensional nanoscale microscopy is demonstrated on an aluminum alloy in local tomography mode

396

Parameters measurement of rigid gas permeable contact lens based on optical coherence tomography  

Science.gov (United States)

Spectral domain optical coherence tomography (OCT) was developed in order to measure the geometric parameters of rigid gas permeable (RGP) contact lens. With custom designed OCT system, an ultra-high axial resolution of 3.3 ?m in lens was achieved. The OCT image was corrected to eliminate the optical distortion and actual surfaces of lens were shown in contour map. Central thickness, lens diameter, base curve and front surface curvature at optical zone were calculated from the contour map. The results match well with the real values measured by conventional instruments. Our research indicates that OCT can be used to test the RGP lens in a simple and exact way.

Zhu, Dexi; Shen, Meixiao; Li, Yiyu

2012-10-01

397

Two-dimensional birefringence imaging in biological tissue using polarization-sensitive optical coherence tomography  

Science.gov (United States)

Using a polarization sensitive Michelson interferometer, we measure 2D images of optical birefringence in bovine tendon as a function of depth with a technique known as optical coherence tomography (OCT). Detection of the polarization state of the signal, formed by interference of backscattered light from the sample and a mirror in the reference arm, gives the optical phase delay between light that has propagated along the fast and slow axes of the birefringent tendon. Images showing the change in birefringence in response to laser irradiation are presented. The technique allows rapid non-contact investigation of tissue structural properties through 2D imaging of birefringence.

de Boer, Johannes F.; Milner, Thomas E.; van Gemert, Martin J. C.; Nelson, J. Stuart

1998-01-01

398

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

Science.gov (United States)

A prototype intraoperative hand-held optical coherence tomography (OCT) imaging probe was developed to provide micron resolution cross-sectional images of subsurface tissue during open surgery. This new ergonomic probe was designed based on electrostatically driven optical fibers, and packaged into a catheter probe in the form factor of clinically accepted Bayonet shaped neurosurgical probes. Optical properties of the probe were measured to have a ~20 ?m spot size, 5 mm working distance and 4 mm field of view. Feasibility of this probe for structural and Doppler shift imaging was tested on porcine femoral blood vessel imaging. PMID:22741085

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

2012-06-01

399

Imaging of polarization properties of the human cornea with phase resolved polarization sensitive optical coherence tomography  

Science.gov (United States)

Optical coherence tomography (OCT) is an emerging technology for high-resolution, non-contact imaging of transparent and scattering media. Polarization sensitive optical coherence tomography (PS-OCT) is a functional extension of OCT that can image birefringent properties of a biological sample. PS-OCT was used to measure and image the retardation and the optic axis orientation of in vitro human cornea. We use a two - channel PS-OCT system employing a phase sensitive recording of the interferometric signals in two orthogonal polarization channels. Using an algorithm based on a Hilbert transform, it is possible to calculate the birefringence and the optic axis orientation of the sample with only one single A- scan. While the retardation information is encoded in the amplitude ratio of the two interferometric signals, the orientation is encoded entirely in their phase difference. We present maps of birefringence and optic axis distribution of the human cornea in longitudinal cross sections and en face images, obtained at the back surface of the cornea. The retardation increases with depth and in radial direction, the optic axis varies in transversal direction. Knowing the retardation and the optic axis distribution of the cornea might improve nerve fiber polarimetry for glaucoma diagnostics.

Gotzinger, Erich; Pircher, Michael; Sticker, Markus; Dejaco-Ruhswurm, Irene; Kaminski, Stephan; Skorpik, Christian; Fercher, Adolf F.; Hitzenberger, Christoph K.

2003-07-01

400

Noise statistics of phase-resolved optical coherence tomography imaging: single-and dual-beam-scan Doppler optical coherence tomography.  

Science.gov (United States)

Noise statistics of phase-resolved optical coherence tomography (OCT) imaging are complicated and involve noises of OCT, correlation of signals, and speckles. In this paper, the statistical properties of phase shift between two OCT signals that contain additive random noises and speckle noises are presented. Experimental results obtained with a scattering tissue phantom are in good agreement with theoretical predictions. The performances of the dual-beam method and conventional single-beam method are compared. As expected, phase shift noise in the case of the dual-beam-scan method is less than that for the single-beam method when the transversal sampling step is large. PMID:24663800

Makita, Shuichi; Jaillon, Franck; Jahan, Israt; Yasuno, Yoshiaki

2014-02-24

 
 
 
 
401

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

Science.gov (United States)

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.

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

2013-02-01

402

Images of arterial tissues using catheter swept source optical coherence tomography  

Science.gov (United States)

Optical coherence tomography images of arterial samples harvested from asymptomatic pigs and from lipid-rich Watanabe heritable hyperlipidemic rabbits were acquired using a fiber catheter-based swept-source optical coherence tomography system (OCT). A quadrature Mach-Zehnder interferometer based on multi-port fiber couplers and a semiconductor optical amplifier (SOA) were employed in the swept-source optical coherence tomography system. The improvement of signal to noise ratio as a result of incorporating the SOA into the configuration translated in an increase of the penetration depth. A fiber probe ending in a fiber ball lens was developed for the arterial imaging. The images acquired by this system offer the possibility to investigate anatomical details located under the surface of the artery such as the intima, media, and adventitia layers (from lumen side) of the blood vessel wall , as well as morphological features specific to artherosclerotic plaques such as lipid pools, fibrous caps, macrophage accumulations and calcified. This report indicates that our improved catheter-based swept source OCT is a potential tool for in vivo intravascular imaging.

Mao, Youxin; Flueraru, Costel; Chang, Shoude; Popescu, Dan P.; Sowa, M. G.

2010-06-01

403

Relation between quantum tomography and optical Fresnel transform  

CERN Document Server

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_

Fan, Hong-yi

2008-01-01

404

High-speed volumetric imaging of cone photoreceptors with adaptive optics spectral-domain optical coherence tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We report the first observations of the three-dimensional morphology of cone photoreceptors in the living human retina. Images were acquired with a high-speed adaptive optics (AO) spectral-domain optical coherence tomography (SD-OCT) camera. The AO system consisted of a Shack-Hartmann wavefront sensor and bimorph mirror (AOptix) that measured and corrected the ocular and system aberrations at a closed-loop rate of 12 Hz. The bimorph mirror was positioned between the XY mechanical scanners and...

Zhang, Yan; Cense, Barry; Rha, Jungtae; Jonnal, Ravi S.; Gao, Weihua; Zawadzki, Robert J.; Werner, John S.; Jones, Steve; Olivier, Scot; Miller, Donald T.

2006-01-01

405

Normal distributions transform in multi-modal image registration of optical coherence tomography and computed tomography datasets  

Science.gov (United States)

In recent years, optical coherence tomography (OCT) has gained increasing attention not only as an imaging device, but also as a navigation system for surgical interventions. This approach demands to register intraoperative OCT to pre-operative computed tomography (CT) data. In this study, we evaluate algorithms for multi-modal image registration of OCT and CT data of a human temporal bone specimen. We focus on similarity measures that are common in this field, e.g., normalized mutual information, normalized cross correlation, and iterative closest point. We evaluate and compare their accuracies to the relatively new normal distribution transform (NDT), that is very common in simultaneous localization and mapping applications, but is not widely used in image registration. Matching is realized considering appropriate image pre-processing, the aforementioned similarity measures, and local optimization algorithms, as well as line search optimization. For evaluation purpose, the results of a point-based registration with fiducial landmarks are regarded as ground truth. First results indicate that state of the art similarity functions do not perform with the desired accuracy, when applied to unprocessed image data. In contrast, NDT seems to achieve higher registration accuracy.

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

2014-03-01

406

Automated Segmentation of Neural Canal Opening and Optic Cup in 3D Spectral Optical Coherence Tomography Volumes of the Optic Nerve Head  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Purpose. To develop an automated approach for segmenting the neural canal opening (NCO) and cup at the level of the retinal pigment epithelium (RPE)/Bruch's membrane (BM) complex in spectral-domain optical coherence tomography (SD-OCT) volumes. To investigate the correspondence and discrepancy between the NCO-based metrics and the clinical disc margin on fundus photographs of glaucoma subjects. Methods. SD-OCT scans and corresponding stereo fundus photographs of the optic nerve head were...

Hu, Zhihong; Abramoff, M. D.; Kwon, Young H.; Lee, Kyungmoo; Garvin, Mona K.

2010-01-01

407

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

Science.gov (United States)

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.

Zhan, Zhigang; Wei, Huajiang; Jin, Ying

2015-02-01

408

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

409

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

Science.gov (United States)

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 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.

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

2010-09-01

410

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

International Nuclear Information System (INIS)

Absorption and emission optical projection tomography (OPT), alternatively referred to as optical computed tomography (optical-CT) and optical-emission computed tomography (optical-ECT), are recently developed three-dimensional imaging techniques with value for developmental biology and ex vivo gene expression studies. The techniques' principles are similar to the ones used for x-ray computed tomography and are based on the approximation of negligible light scattering in optically cleared samples. The optical clearing is achieved by a chemical procedure which aims at substituting the cellular fluids within the sample with a cell membranes' index matching solution. Once cleared the sample presents very low scattering and is then illuminated with a light collimated beam whose intensity is captured in transillumination mode by a CCD camera. Different projection images of the sample are subsequently obtained over a 3600 full rotation, and a standard backprojection algorithm can be used in a similar fashion as for x-ray tomography in order to obtain absorption maps. Because not all biological samples present significant absorption contrast, it is not always possible to obtain projections with a good signal-to-noise ratio, a condition necessary to achieve high-quality tomographic reconstructions. Such is the case for example, for early stage's embryos. In this work we demonstrate how, through the use of a random noise removal algorithm, the image quality of the roval algorithm, the image quality of the reconstructions can be considerably improved even when the noise is strongly present in the acquired projections. Specifically, we implemented a block matching 3D (BM3D) filter applying it separately on each acquired transillumination projection before performing a complete three-dimensional tomographical reconstruction. To test the efficiency of the adopted filtering scheme, a phantom and a real biological sample were processed. In both cases, the BM3D filter led to a signal-to-noise ratio increment of over 30 dB on severe noise-affected reconstructions revealing original-noise-hidden-image details. These results show the utility of the BM3D approach for OPT under typical conditions of very low light absorption, suggesting its implementation as an efficient alternative to other filtering schemes such as for example the median filter.

411

Spontaneous progression of a full-thickness macular microhole to a lamellar macular hole in spectral domain optical coherence tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We presented a case of full-thickness macular hole progressing into lamellar macular hole as seen in the spectral domain optical coherence tomography. Short review of the literature regarding the pathogenesis of lamellar hole was presented and discussed.

Caramoy, Albert; Fauser, Sascha; Kirchhof, Bernd

2011-01-01

412

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

International Nuclear Information System (INIS)

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.

413

Differentiation of ex vivo human breast tissue using polarization-sensitive optical coherence tomography.  

Science.gov (United States)

Successful treatment of breast cancer typically requires surgical removal of the tumor. Optical coherence tomography (OCT) has been previously developed for real-time imaging of the surgical margin. However, it can be difficult to distinguish between normal stromal tissue and cancer tissue based on scattering intensity and structure alone. Polarization-sensitive optical coherence tomography (PS-OCT) is sensitive to form birefringence of biological tissue. We report on the development of a high-speed PS-OCT system and imaging of ex vivo human breast tissue, showing enhanced contrast between healthy and cancerous tissues based upon collagen content confirmed with corresponding histology. These results demonstrate the feasibility of using PS-OCT to supplement structural OCT as a possible method for intraoperative tumor margin evaluation. PMID:25360360

South, Fredrick A; Chaney, Eric J; Marjanovic, Marina; Adie, Steven G; Boppart, Stephen A

2014-10-01

414

On-chip spectrometer for low-cost optical coherence tomography  

Science.gov (United States)

Tornado Spectral Systems has developed a new spectrometer called OCTANE, the Optical Coherence Tomography Advanced Nanophotonic Engine, consisting of chip-based spectrometers for spectral domain optical coherence tomography (SD-OCT) systems. These devices include planar lightwave circuits with integrated waveguides fabricated on a planar silicon substrate. Our commercial prototypes include a NIR system centered at a wavelength of 860 nm, a spectral bandwidth of 70 nm, and 2048 output channels to record TE and TM polarizations independently at an 80 kHz line scan rate. Intended to support low-cost, high-volume applications, these spectrometers are well-suited to SD-OCT for both biological and industrial non-destructive testing applications.

Nitkowski, Arthur; Preston, Kyle; Sherwood-Droz, Nicolás.; Schmidt, Bradley S.; Hajian, Arsen R.

2014-03-01

415

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

Science.gov (United States)

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

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

2002-07-01

416

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

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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.

Domalpally Amitha

2010-01-01

417

Phase-contrast diffuse optical tomography for in vivo breast imaging: a two-step method  

International Nuclear Information System (INIS)

We present a two-step reconstruction method that can qualitatively and quantitatively improve the reconstruction of tissue refractive index (RI) distribution by phase-contrast diffuse optical tomography (PCDOT). In this two-step method, we first recover the distribution of tissue absorption and scattering coefficients by conventional diffuse optical tomography to obtain the geometrical information of lesions, allowing the incorporation of geometrical information as a priori in the PCDOT reconstruction using a locally refined mesh. The method is validated by a series of phantom experiments and evaluated using in vivo data from 42 human subjects. The results demonstrate clear contrast of RI between the lesion and the surroundings, making the image interpretation straightforward. The sensitivity and specificity from these 42 cases are both 81% when RI is used as an imaging parameter for distinguishing between malignant and benign lesions.

418

A haemodynamic response function model in spatio-temporal diffuse optical tomography  

International Nuclear Information System (INIS)

Diffuse optical tomography (DOT) is a new and effective technique for functional brain imaging. It can detect local changes in both oxygenated and deoxygenated haemoglobin concentrations in tissue based on differential absorption at multiple wavelengths. Traditional methods in spatio-temporal analysis of haemoglobin concentrations in diffuse optical tomography first reconstruct the spatial distribution at different time instants independently, then look at the temporal dynamics on each pixel, without incorporating any temporal information as a prior in the image reconstruction. In this work, we present a temporal haemodynamic response function model described by a basis function expansion, in a joint spatio-temporal DOT reconstruction of haemoglobin concentration changes during simulated brain activation. In this joint framework, we simultaneously employ spatial regularization, spectral information and temporal assumptions. We also present an efficient algorithm for solving the associated large-scale systems. The expected improvements in spatial resolution and contrast-to-noise ratio are illustrated with simulations of human brain activation

419

Utilizing optical coherence tomography in the nondestructive and noncontact measurement of egg shell thickness.  

Science.gov (United States)

The goal of this study was to measure the thickness of egg shells without any contact and by utilizing a nondestructive method that sends infrared light beam on the egg. We obtain measurement resolutions on the order of 7 ?m up to a penetration depth of 1.7 mm from the actual surface of the egg shell. The measurement results we obtained show that optical coherence tomography can be used to accurately determine the egg shell thickness. Scanning the light beam over the surface allows for measuring the egg profile and monitoring the variations of shell thickness. Since this information gives a quantitative value for the uniformity of the egg shell structure, we anticipate that optical coherence tomography may be used in the quantitative evaluation of egg quality in in-line automated inspection systems. PMID:25133208

Sabuncu, Metin; Akdo?an, Mete

2014-01-01

420

Laser Tomography Adaptive Optics (LTAO): A performance study  

CERN Document Server

We present an analytical derivation of the on-axis performance of Adaptive Optics systems using a given number of guide stars of arbitrary altitude, distributed at arbitrary angular positions in the sky. The expressions of the residual error are given for cases of both continuous and discrete turbulent atmospheric profiles. Assuming Shack-Hartmann wavefront sensing with circular apertures, we demonstrate that the error is formally described by integrals of products of three Bessel functions. We compare the performance of Adaptive Optics correction when using natural, Sodium or Rayleigh laser guide stars. For small diameter class telescopes (~5m), we show that a few number of Rayleigh beacons can provide similar performance to that of a single Sodium laser, for a lower overall cost of the instrument. For bigger apertures, using Rayleigh stars may not be such a suitable alternative because of the too severe cone effect that drastically degrades the quality of the correction.

Tatulli, E

2013-01-01

 
 
 
 
421

Spectral Domain Optical Coherence Tomography in Diffuse Unilateral Subacute Neuroretinitis  

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Purpose. To describe the SD-OCT findings in patients with diffuse unilateral subacute neuroretinitis (DUSN) and evaluate CRT and RNFL thickness. Methods. Patients with clinical diagnosis of DUSN who were submitted to SD-OCT were included in the study. Complete ophthalmologic examination and SD-OCT were performed. Cirrus scan strategy protocols used were 200 × 200 macular cube, optic nerve head cube, and HD-5 line raster. Results. Eight patients with DUSN were ...

Garcia Filho, Carlos Alexandre A.; Soares, Ana Claudia Medeiros A. G.; Fernando Marcondes Penha; Carlos Alexandre de Amorim Garcia

2011-01-01

422

Retinal cone mosaic imaged with transverse scanning optical coherence tomography  

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We improved our recently reported retinal OCT system based on transverse priority scanning to achieve high resolution in both the transverse and the axial directions. The implementation of an additional SLO channel enables precise on-line focusing. The system enables imaging of the human retinal cone mosaic off the foveal center without adaptive optics. We demonstrate, for what is believed to be the first time, cone mosaic imaging simultaneously in the scanning laser ophthalmoscope and optica...

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

2006-01-01

423

Retinal nerve fiber layer evaluation in multiple sclerosis with spectral domain optical coherence tomography  

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Full Text Available Aziz A Khanifar1, George J Parlitsis1, Joshua R Ehrlich1, Grant D Aaker1, Donald J D’Amico1, Susan A Gauthier2, Szilárd Kiss11Departments of Ophthalmology, 2Neurology, Judith Jaffe Multiple Sclerosis Center, Weill Cornell Medical College, New York, USAPurpose: Histopathologic studies have reported retinal nerve fiber layer (RNFL thinning in various neurodegenerative diseases. Attempts to quantify this loss in vivo have relied on ­time-domain optical coherence tomography (TDOCT, which has low resolution and requires substantial interpolation of data for volume measurements. We hypothesized that the significantly higher resolution of spectral-domain optical coherence tomography (SDOCT would better detect RNFL changes in patients with multiple sclerosis, and that RNFL thickness differences between eyes with and without optic neuritis might be identified more accurately.Methods: In this retrospective case series, patients with multiple sclerosis were recruited from the Judith Jaffe Multiple Sclerosis Center at Weill Cornell Medical College in New York. Patients with a recent clinical diagnosis of optic neuritis (less than three months were excluded. Eyes with a history of glaucoma, optic neuropathy (other than multiple sclerosis-related optic neuritis, age-related macular degeneration, or other relevant retinal and/or optic nerve disease were excluded. Both eyes of each patient were imaged with the Heidelberg Spectralis® HRA + OCT. RNFL and macular thickness were measured for each eye using the Heidelberg OCT software. These measurements were compared with validated published normal values, and were modeled as linear functions of duration of disease. The odds of an optic neuritis diagnosis as a function of RNFL and macular thickness were calculated.Results: Ninety-four eyes were prospectively evaluated using OCT. Ages of patients ranged from 26 to 69 years, with an average age of 39 years. Peripapillary RNFL thinning was demonstrated in multiple sclerosis patients; mean RNFL thickness was 88.5 µm for individuals with multiple sclerosis compared with a reported normal value of 97 µm (P < 0.001. Eyes with a history of optic neuritis had more thinning compared with those without optic neuritis (83.0 µm versus 90.5 µm, respectively, P = 0.02. No significant differences were observed in macular thickness measurements between eyes with and without optic neuritis, nor were macular thickness measurements significantly different from normal values. As a function of multiple sclerosis duration and controlling for age, RNFL thickness was decreased in patients with a duration of multiple sclerosis greater than five years compared with those with a duration less than or equal to one year (P = 0.008.Conclusions: Patients with a history of multiple sclerosis had RNFL thinning that was detectable on SDOCT. Decreasing RNFL thickness in eyes with optic neuritis was found, and the odds of having optic neuritis were increased significantly with decreasing RNFL thickness. Average RNFL thinning with increasing duration of disease was an excellent predictor of a reported history of optic neuritis. SDOCT retinal imaging may represent a high-resolution, objective, noninvasive, and easily quantifiable in vivo biomarker of the presence of optic neuritis and severity of multiple sclerosis.Keywords: multiple sclerosis, spectral-domain optical coherence tomography, optical ­coherence tomography, nerve fiber layer, nerve fiber layer thickness, optic neuritis

Aziz A Khanifar

2010-09-01

424

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

Science.gov (United States)

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

Alfonso, Fernando; Cárdenas, Alberto; Ibáñez, Borja

2013-12-01

425

Real-time three-dimensional optical coherence tomography image-guided core-needle biopsy system  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Kuo, Wei-cheng; Kim, Jongsik; Shemonski, Nathan D.; Chaney, Eric J.; Spillman, Darold R.; Boppart, Stephen A.

2012-01-01

426

Posterior chamber compartments demonstrated by optical coherence tomography, in silicone-filled eyes, following macular hole surgery.  

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PURPOSE: To report visualization with optical coherence tomography of a prefoveal space in silicone oil-filled eyes following surgery for idiopathic macular hole. METHODS: Seven eyes of seven consecutive patients undergoing macular hole surgery with silicone oil tamponade were prospectively evaluated with optical coherence tomography preoperatively, on the first postoperative day, after 6 weeks and before removal of silicone oil. RESULTS: In all seven eyes the posterior face of the silicone o...

Satchi, K.; Patel, Ck

2005-01-01

427

Full-Field Birefringence Imaging by Thermal-Light Polarization-Sensitive Optical Coherence Tomography. I. Theory  

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A method for measuring birefringence by use of thermal-light polarization-sensitive optical coherence tomography is presented. The use of thermal light brings to polarization-sensitive optical coherence tomography a resolution in the micrometer range in three dimensions. The instrument is based on a Linnik interference microscope and makes use of achromatic quarter-wave plates. A mathematical representation of the instrument is presented here, and the detection scheme is described, together w...

Moreau, Julien; Loriette, V.; Boccara, A. C.

2003-01-01

428

High-definition optical coherence tomography: adapted algorithmic method for pattern analysis of inflammatory skin diseases: a pilot study  

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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 correlate dermatopathologic descriptors of inflammatory skin conditions with epidermal alteration to features observed by HD-OCT. Secondly, to assess the discriminative accuracy of common inflammatory re...

Boone, Marc; Norrenberg, Sarah; Jemec, Gregor; Del Marmol, Ve?ronique

2013-01-01

429

Acousto-optical coherence tomography using random phase jumps on ultrasound and light  

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Imaging objects embedded within highly scattering media by coupling light and ultrasounds (US) is a challenging approach. In deed, US enable direct access to the spatial localization, though resolution can be poor along their axis (cm). Up to now, several configurations have been studied, giving a millimetric axial resolution by applying to the US a microsecond pulse regime, as is the case with conventional echography. We introduce a new approach called Acousto-Optical Coherence Tomography (A...

Lesaffre, Max; Farahi, S.; Gross, Michel; Delaye, Philippe; Boccara, Claude; Ramaz, Franc?ois

2009-01-01

430

Comparison of central corneal thickness measured by anterior segment optical coherence tomography, pentacam and ultrasonic pachymetry  

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AIM: To investigate and analyze the differences in central corneal thickness(CCT)measurement by anterior segment optical coherence tomography(AS-OCT), pentacam rotating Scheimpflug camera and ultrasonic pachymetry(USP). METHODS: The retrospective study measured CCT of 43 patients(86 eyes)performed excimer laser myopia corrective surgery by the same examiner using RTVue AS-OCT with an anterior segment adaptor, pentacam rotating Scheimpflug camera, and PACSCAN300P USP. Data of three groups w...

Wei Zhao; Ting Wu; Ze-Hong Dong; Jie Feng; Yu-Feng Ren; Yu-Sheng Wang

2013-01-01

431

IN VIVO FIBER BASED HIGH SPEED OPTICAL COHERENCE TOMOGRAPHY IMAGES OF HUMAN FINGER  

Directory of Open Access Journals (Sweden)

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.

S. Kumari

2011-08-01

432

Assessment of optical coherence tomography for metrology applications in high-scattering ceramic materials  

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Large-scale and cost-effective manufacturing of ceramic micro devices based on tape stacking requires the development of inspection systems to perform high-resolution in-process quality control of embedded manufactured cavities, metal structures and defects. In this work, alumina ceramic samples are evaluated by optical coherence tomography (OCT) operating at 1.3?m wavelength and some dimensional data are obtained by dedicated image processing and segmentation. Layer thicknesses can be measu...

Su, Rong

2012-01-01

433

Optical coherence tomography for live phenotypic analysis of embryonic ocular structures in mouse models  

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Mouse models of ocular diseases provide a powerful resource for exploration of molecular regulation of eye development and pre-clinical studies. Availability of a live high-resolution imaging method for mouse embryonic eyes would significantly enhance longitudinal analyses and high-throughput morphological screening. We demonstrate that optical coherence tomography (OCT) can be used for live embryonic ocular imaging throughout gestation. At all studied stages, the whole eye is within the imag...

Larina, Irina V.; Syed, Saba H.; Sudheendran, Narendran; Overbeek, Paul A.; Dickinson, Mary E.; Larin, Kirill V.

2012-01-01

434

Velocity Variation Assessment of Red Blood Cell Aggregation with Spectral Domain Doppler Optical Coherence Tomography  

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We propose spectral domain Doppler optical coherence tomography (SD-D-OCT) to qualitatively measure red blood cell aggregation. Variance/standard deviation (SD) of the Doppler frequency spectrum in Doppler variance imaging of flowing blood under shearing conditions was developed as a new aggregation index. In in vitro microchannel-flow experiments, porcine blood at various hematocrits with aggre