23. K. W. Gossage, T. S. Tkaczyk, J. J. Rodriguez, and J. K. Barton, “Texture analysis of opticalcoherence tomography images: feasibility for tissue classification,” J. Biomed. Opt. 8 共3兲, 570–575 共2003兲.
24. C. A. Lingley-Papadopoulos, M. H. Loew, M. J. Manyak, and J. M. Zara, “Computer recognition of cancer in the urinary bladder using opticalcoherence tomography and texture analysis,” J. Biomed. Opt.
Keywords: Opticalcoherence tomography, phantoms, poly (vynil alcohol), arteries, atherosclerosis
We previously reported a method for the fabrication of coronary artery phantoms for OpticalCoherence Tomography (OCT) . When imaged by OCT, coronary arteries show distinctive signal by each of their layers: the intima, the media and the adventitia. The method consists of mimicking the OCT signal for each layer of the arteries and building the phantoms in the shape of multilayer tubes. To match the OCT signal of artery layers, particles of alumina are used to obtain the desired backscattering, and particles of carbon black are used to further adjust the total attenuation. The particles are mixed into a transparent silicone, which insures high durability to the phantoms. We also demonstrated that by using a specific formulation of silicone, the linear elasticity observed for arteries at low deformation can be mimicked. However, the silicone elasticity is linear for all deformations, whereas arteries, for high deformations, show an important non-linear effect. This effect is called the strain hardening. It translates into a significant increase in stiffness when a certain deformation is reached.
Full-Field OpticalCoherence Tomography. Full-field OCT 1,2 is a variant of conventional OCT 3 in which two-
dimensional (2D) en face images are captured on a camera and three-dimensional (3D) data sets may be obtained by scanning in the depth direction. This configuration and the use of a white light source allow for higher axial and cross-sectional resolution than conventional OCT, on the order of 1 lm. No contrast agents are required as contrast is entirely endogenous. Full-field OCT can therefore perform micrometer resolution 3D imaging noninvasively in fresh or fixed ex vivo biological tissue samples. In retina, FFOCT enables imaging of fresh or fixed flat- mounted tissue at 1 lm 3 resolution (i.e., showing cellular
Keywords: opticalcoherence tomography, mechanical properties, angioplasty, balloon, phantom.
The question underlying this paper is: “Can we extract relevant mechanical properties from an intravascular opticalcoherence tomography (IVOCT) measurement like that of Video 1? Video 1 shows the IVOCT monitoring of the inflation of an angioplasty balloon within a coronary artery obtained in a beating heart setup . After the balloon is sufficiently inflated to fill the lumen, any further inflation cause a deformation of the artery wall. The response of the system thus includes the mechanical response of the tissue surrounding the balloon. Consequently, mechanical properties can indeed be extracted. The true question is then: “Considering the multiple sources of uncertainty in such a measurement, can mechanical properties be measured with an accuracy high enough to be relevant for diagnosis or to provide significant patient specific information?” These sources of uncertainty include, for example, the accuracy of OCT imaging, the complexity of the tissue under investigation, and the assumptions underlying the mechanical analysis. The question is not only relevant for balloon inflation monitored by IVOCT, but for any other OCT measurement where a balloon is inflated that may deform the surrounding tissue, like in some endoscopic OCT applications.
Multimodal imaging of a left eye with mixed type 1 and type 2 choroidal neovascularization. (Top left) Color fundus photography. Retinal pigment epithelium (RPE) clumps and
mottling, and subretinal hemorrhage (white arrow) surrounded by edematous retina and drusen.; (Top center) and (Top right) Different stages fluorescein angiography. Red dashed- line representing the occult component; yellow dashed-line representing the classic component.; (Bottom left) Spectral-domain ~840 nm wavelength opticalcoherence tomography angiography (OCTA) image and; (Bottom center) Swept-source ~1050 nm wavelength OCTA image. Red dashed-line representing the type 1 component; yellow dashed-line representing the type 2 component.; (Bottom right) Corresponding opticalcoherence tomography B-scan. RPE represented as red dashed-line. Type 1 component (red arrow) and type 2 component (yellow arrow).
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Opticalcoherence tomography and and coherence domain optical methods in Biomedicine, BIOS 2011 [Proceedings], 2011-01-23
Keywords: OpticalCoherence Tomography, phantoms, atherosclerosis, arteries
Intravascular opticalcoherence tomography (IV-OCT) has now reached a stage close to widespread clinical use. A review of the recent technology and applications of OCT in cardiology can be found in Ref. . Tremendous progress has been made on the technical side and assessment of IV-OCT as a diagnostic tool in cardiology has been convincingly demonstrated. A few companies are now working towards the commercialization of the technology. Acceptance in the clinical world is under way since IV-OCT is already approved in a few countries. The ﬁeld is nevertheless still missing diseased artery phantoms. These are essential to ease further development of the technology, to insure training of personnel, and to serve as calibration and validation targets. In the current paper, we present a method to produce artery phantoms containing diseased structures. We ﬁrst recall our previously described method to fabricate phantoms of normal arteries. We then describe how the fabrication process is modiﬁed to introduce structures that provide the OCT signatures of a calciﬁcation and of a lipid pool. We ﬁnally present OCT images of diseased artery phantoms that were fabricated with the proposed method.
∗ Corresponding author: firstname.lastname@example.org
Compiled October 11, 2012
Acousto-OpticalCoherence Tomography (AOCT) consists in using random phase jumps on ultrasound and light to achieve a millimeter resolution when imaging thick scattering media. We combined this technique with heterodyne off-axis digital holography. Two-dimensional images of absorbing objects embedded in scattering phantoms are obtained with a good signal to noise ratio. We study the impact of the phase modulation characteristics on the amplitude of the acousto-optic signal and on the contrast and apparent size of the absorbing inclusion. c
2012 Optical Society of America
In 1991, Huang et al. 1 introduced opticalcoherence tomogra- phy 共OCT兲 by providing examples on two different biological systems: the retina and the coronary artery. The subsequent development of OCT in ophthalmology has led to a rich col- lection of research literature and to the commercialization of OCT systems by numerous companies. It has culminated in the adoption of OCT in ophthalmological clinics. The more challenging development of intravascular OCT imaging 共IVOCT兲 evolved through well-defined steps. The clinical rel- evance of OCT measurements was clearly demonstrated as early as 1996. 2 , 3 Catheter-based measurements on excised hu- man coronary arteries were first reported in 1996. 4 First in-
OpticalCoherence Tomography (OCT) is a high resolution, non-destructive, imaging technique developed in the last decade. It can be used to explore the internal structure of an object in micro meter level. Recently, we have used OCT to extract the tomographic images of different types of jades. The experimental results show that the internal structures, including the marks, textures at different depths, can be observed clearly within 4 mm depth (see Pictures part I). And also, we noticed that there is about 20dB difference of the OCT signal intensity between jade and its wrapping materials. These results show that the OCT technology can be applied to the jade industry. Almost all the 4 steps of the jade procedure can be greatly facilitated, and in addition, it can efficiently avoid the waste in raw material preparing as well as failures in artistically carving, with the help of an OCT system.
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OpticalCoherence Tomography Characterization of Balloon Diameter and Wall Thickness
Azarnoush, Hamed; Bourezak, Rafik; Vergnole, Sébastien; Lamouche, Guy; Boulet, Benoît
5. SUMMERY AND DISCUSSION
Opticalcoherence tomography paves a new avenue for exploring and analysing the internal structure of an object. The micron level resolution makes it unique to other tomographic imaging technology. OCT technology has potential applications to many fields, including medical, security, environment, and industrial. In this paper, we have briefly described the principle of different OCT systems and shown the possibility of their application in jade exploration and analysis.
Laser Doppler flowmetry is a technique that allows noninvasive measurement of hemodynamic parameters of the optic nerve head (ONH), iris, and subfoveal choroidal circulation. Using laser Doppler flowmetry, the mean speed of the erythrocytes in the sampling volume and the number of moving erythrocytes in this volume can be determined. Several studies with laser Doppler flowmetry showed a decrease in volume in the choroidal circulation in various diseases like diabetic retinopathy, AMD, and retinitis pigmentosa. 14–16 Ultrasound also plays a role in the diagnosis and management of a variety of vitreoretinal pathologies, especially in the presence of opaque media. Additionally, it can detect and characterize tumors and other thickenings in the choroid and retina. However, the image resolution is low, which makes the detection of small changes in the choroid difficult. 17 Although these techniques are useful for determining vessel abnormalities or changes in the choroidal blood flow, they do not provide three-dimensional anatomical information about the RPE or the choroidal layers. The development of opticalcoherence tomography (OCT) makes it possible to have high-quality, cross-sectional images of the macula or ONH, analogous to ultrasonography but with greater resolution. However, adequate morphologic examination of the choroid using OCT has not been possible until recently, owing to its posterior location and the presence of pigmented cells in the RPE that attenuate the incident light. Recent reports demonstrated successful examination and measurement of choroidal thickness in normal and pathologic states using spectral-domain opticalcoherence tomography (SDOCT) instruments. 4,18–22
2 Clinical Investigation Center 1423, Quinze-Vingts Hospital, Paris, France
Abstract. Directional opticalcoherence tomography (D-OCT) reveals re flec- tance properties of retinal structures by changing the incidence angle of the light beam. As no commercially available OCT device has been designed for such use, image processing is required to homogenize the grey levels between off-axis images before differential analysis. We describe here a method for automated analysis of D-OCT images and propose a color representation to highlight angle-dependent structures. Clinical results show that the proposed approach is robust and helpful for clinical interpretation.
Keywords: opticalcoherence tomography; multi-focal imaging; chromatic focal shift
Opticalcoherence tomography (OCT) is an imaging modality based on low coherence interferometry [ 1 ]. Compared to other optical methods such as multiphoton and confocal microscopies, a typical OCT system operates with reduced resolution but offers larger imaging fields and deeper penetration depth in biological samples. The axial and transverse resolutions of OCT are set by the spectral bandwidth of the light source and the numerical aperture (NA) of the imaging lens, respectively. While higher NA lenses can be used to increase transverse resolution in OCT, this results in a limited depth of focus (DoF). Therefore, most systems operate with moderate transverse resolutions that approximately match DoF to the relatively long penetration depth of OCT.
Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
We describe depth-resolved microscopy of cortical hemodynamics with high-speed spectral/Fourier domain opticalcoherence tomography (OCT). Stimulus-evoked changes in blood vessel diameter, flow, and total hemoglobin were measured in the rat somatosensory cortex. The results show OCT measurements of hemodynamic changes during functional activation and represent an important step toward understanding functional hyperemia at the microscopic level.
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Speckle Size in OpticalCoherence Tomography
Lamouche, G.; Bisaillon, C.-É.; Maciejko, R.; Dufour, M.; Monchalin, J. -P.
2. SSOCT SPECTRAL SIGNAL
In Swept-Source OpticalCoherence Tomography (SSOCT), the broadband light source plays an important role. The linewidth and output power determinate the imaging range of an SSOCT system. The bandwidth of the light source places the main barrier for the imaging resolution. At current stage, most commercial swept-sources have a bandwidth about 100 nm corresponding to an axial resolution around 14 μm in air.
With over 100 million cumulative clinical imaging procedures performed in ophthalmology and the technology gaining increasing acceptance in cardiology, dermatology, and
gastroenterology, opticalcoherence tomography (OCT) is becoming an increasingly important tool for micrometer-resolution three-dimensional (3D) sub-surface imaging [1–4]. Modern OCT systems achieve high detection sensitivity and high speed by performing measurements in the Fourier domain and Fourier transforming an interference spectrum to generate axial scans (A-scans), which characterize reflection/backscatter versus the range [5–9]. The imaging range of Fourier-domain OCT has been limited to a few centimeters [4,10,11], thereby restricting its applications. In this study, we demonstrate an order of magnitude longer imaging range than previously demonstrated [10,11]. We demonstrate 3D macroscopic imaging at a 100 kHz axial scan rate with 15 µm depth resolution, near-shot- noise-limited sensitivity, sub-surface tomographic imaging, and a meter-scale imaging range