WorldWideScience
 
 
1

[Optical coherence tomography].  

Science.gov (United States)

Optical coherence tomography is a novel, noninvasive, noncontact and repetitive imaging technique which produces high depth resolution cross-sectional tomographs of ocular tissue. It's value is given by the possibility of achieving pseudo-histological images of the target tissue. It is optically based, analogue to ultrasound B-scan examination and similar to laser reflectometry. Optical coherence tomography involves shining low-level infrared light on a tissue specimen, an interferometer and a computerized imaging system. The most attractive applications of optical coherence tomography are the diseases of the retina such as: central serous retinopathy, macular hole, chronic macular edema, age-related macular degenerescence. PMID:11021132

Gafencu, O

2000-01-01

2

Optical coherence tomography  

International Nuclear Information System (INIS)

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

2010-01-01

3

Optical coherent tomography  

UK PubMed Central (United Kingdom)

A surface emission laser light source is used as a tunable laser light source. Since the surface emission laser light source can realize a broad frequency scanning range at a high speed and in the single mode, a coherent length is longer than that of a multi mode light source. For this reason, when a tomography image is calculated by executing the Fourier transform for an output obtained from an interference optical device, measuring depth can be deepened.

CHONG CHANGHO

4

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

5

Blood optical clearing by optical coherence tomography.  

UK PubMed Central (United Kingdom)

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.

Zhernovaya O; Tuchin VV; Leahy MJ

2013-02-01

6

Optical Coherence Tomography Evaluation of Tracheal Inflammation.  

Science.gov (United States)

Methods for obtaining real-time in-vivo histologic resolution non- invasive endoscopic optical imaging would be a major advance for pulmonary diagnostics and treatment in civilian and military medical applications. Optical coherence tomography (OCT) is a ...

N. M. Hanna W. Jung Z. Chen U. Mahmood R. Mina-Araghi

2004-01-01

7

Integrated diffuse optical tomography and photoacoustic tomography: phantom validations.  

Science.gov (United States)

We designed, fabricated and tested a novel imaging system that fuses diffuse optical tomography (DOT) and photoacoustic tomography (PAT) in a single platform. This platform takes advantages of both DOT and PAT, and can potentially provide dual-modality two dimensional functional and cellular images of the breast quantitatively. Here we describe this integrated platform along with initial tissue phantom validations. PMID:21833371

Li, Xiaoqi; Xi, Lei; Jiang, Ruixin; Yao, Lei; Jiang, Huabei

2011-07-21

8

Integrated diffuse optical tomography and photoacoustic tomography: phantom validations.  

UK PubMed Central (United Kingdom)

We designed, fabricated and tested a novel imaging system that fuses diffuse optical tomography (DOT) and photoacoustic tomography (PAT) in a single platform. This platform takes advantages of both DOT and PAT, and can potentially provide dual-modality two dimensional functional and cellular images of the breast quantitatively. Here we describe this integrated platform along with initial tissue phantom validations.

Li X; Xi L; Jiang R; Yao L; Jiang H

2011-08-01

9

Optical coherence tomography in dermatology  

Science.gov (United States)

Optical coherence tomography (OCT) is a noninvasive diagnostic method that offers a view into the superficial layers of the skin in vivo in real-time. An infrared broadband light source allows the investigation of skin architecture and changes up to a depth of 1 to 2 mm with a resolution between 15 and 3 ?m, depending on the system used. Thus OCT enables evaluation of skin lesions, especially nonmelanoma skin cancers and inflammatory diseases, quantification of skin changes, visualization of parasitic infestations, and examination of other indications such as the investigation of nails. OCT provides a quick and useful diagnostic imaging technique for a number of clinical questions and is a valuable addition or complement to other noninvasive imaging tools such as dermoscopy, high-frequency ultrasound, and confocal laser scan microscopy.

Sattler, Elke; Kästle, Raphaela; Welzel, Julia

2013-06-01

10

Optical coherence tomography in dermatology.  

UK PubMed Central (United Kingdom)

Optical coherence tomography (OCT) is a noninvasive diagnostic method that offers a view into the superficial layers of the skin in vivo in real-time. An infrared broadband light source allows the investigation of skin architecture and changes up to a depth of 1 to 2 mm with a resolution between 15 and 3 ?m, depending on the system used. Thus OCT enables evaluation of skin lesions, especially nonmelanoma skin cancers and inflammatory diseases, quantification of skin changes, visualization of parasitic infestations, and examination of other indications such as the investigation of nails. OCT provides a quick and useful diagnostic imaging technique for a number of clinical questions and is a valuable addition or complement to other noninvasive imaging tools such as dermoscopy, high-frequency ultrasound, and confocal laser scan microscopy.

Sattler E; Kästle R; Welzel J

2013-06-01

11

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

12

Fluorescence diffuse optical tomography using upconverting nanoparticles  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Fluorescence diffuse optical tomography (FDOT) can provide important information in biomedical studies. In this ill-posed problem, suppression of background tissue autofluorescence is of utmost importance. We report a method for autofluorescence-insensitive FDOT using nonlinear upconverting nanopart...

Xu, Can; Axelsson, Johan; Andersson-Engels, Stefan

13

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

1990-01-01

14

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

15

Clinical applications of optical coherence tomography.  

Science.gov (United States)

Optical coherence tomography is a new diagnostic tool for high-resolution imaging of ocular tissues. Ocular coherence tomography produces cross-sectional images of the retina with a longitudinal resolution of 10 microns. This provides the most highly resolved retinal images in vivo when compared with other available techniques. It has been used to study the anatomy and pathogenesis of various ocular disorders affecting the posterior segment. These include vitreomacular traction syndrome, macular hole, retinoschisis, macular edema, central serous chorioretinopathy, subretinal neovascularization, age-related maculopathy, optic nerve disorders, and nerve fiber layer evaluation in glaucoma. PMID:10537777

Baumal, C R

1999-06-01

16

Clinical applications of optical coherence tomography.  

UK PubMed Central (United Kingdom)

Optical coherence tomography is a new diagnostic tool for high-resolution imaging of ocular tissues. Ocular coherence tomography produces cross-sectional images of the retina with a longitudinal resolution of 10 microns. This provides the most highly resolved retinal images in vivo when compared with other available techniques. It has been used to study the anatomy and pathogenesis of various ocular disorders affecting the posterior segment. These include vitreomacular traction syndrome, macular hole, retinoschisis, macular edema, central serous chorioretinopathy, subretinal neovascularization, age-related maculopathy, optic nerve disorders, and nerve fiber layer evaluation in glaucoma.

Baumal CR

1999-06-01

17

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

18

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.)

2010-01-01

19

Optical coherence tomography. Development, principles, applications  

Energy Technology Data Exchange (ETDEWEB)

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.)

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

2010-07-01

20

Polarization sensitive optical coherence tomography in dentistry  

International Nuclear Information System (INIS)

Optical coherence tomography (OCT) is a noninvasive and noncontact technique for obtaining cross-sectional images of biologic structure, which was initially introduced to depict the transparent tissue of the eye. It employs the partial coherence properties of a light source to image structures with high resolution (

1998-01-01

 
 
 
 
21

Computed tomography in optic neuritis  

International Nuclear Information System (INIS)

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

1979-01-01

22

Optical coherence tomography: Principles and applications  

Energy Technology Data Exchange (ETDEWEB)

Optical coherence tomography (OCT) uses low coherence interferometric techniques to obtain high resolution ({approximately}1 {mu}m), high sensitivity ({approximately}100 dB) reflectivity profiles of a sample. One, two, and three dimensional images of the internal microstructure of a sample`s optical properties such as refractive index, absorption coefficient, scattering coefficient, and birefringence can be obtained. The basic principles and limitations of OCT will be reviewed. The relative merits of OCT compared to other optical imaging modalities such as OTDR`s, OFDR`s, and conventional optical microscopy will be addressed. We have developed a system that provides {open_quotes}real time{close_quotes} 2-dimensional false-color tomographs. We will describe the system`s design and performance. A variety of applications such as measurements on fiber optic, integrated optic, materials, and biological tissues will be presented.

Swanson, E.A.; Hee, M.R.; Tearney, G.J.; Fujimoto, J.G. [Massachusetts Institute of Technology, Lexington, MA (United States)

1995-12-31

23

Single-Scattering Optical Tomography  

CERN Document Server

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

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

2007-01-01

24

Computerised tomography in calcified optic nerve drusen  

International Nuclear Information System (INIS)

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

1984-01-01

25

Optical coherence tomography findings of quinine poisoning  

Directory of Open Access Journals (Sweden)

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

John Christoforidis; Robert Ricketts; Theodore Loizos; et al

2011-01-01

26

Endoscopic, rapid near-infrared optical tomography.  

Science.gov (United States)

This is believed to be the first demonstration of near-infrared (NIR) optical tomography employed at the endoscope scale and at a rapid sampling speed that allows translation to in vivo use. A spread-spectral-encoding technique based on a broadband light source and linear-to-circular fiber bundling was used to provide endoscopic probing of many source-detector fibers for tomography as well as parallel sampling of all source-detector pairs for rapid imaging. Endoscopic NIR tomography at an 8 Hz frame rate was achieved in phantoms and tissue specimens with a 12 mm probe housing eight sources and eight detectors. This novel approach provides the key feasibility studies to allow this blood-based contrast imaging technology to be attempted in detection of cancer in internal organs via endoscopic interrogation. PMID:16969408

Piao, Daqing; Xie, Hao; Zhang, Weili; Krasinski, Jerzy S; Zhang, Guolong; Dehghani, Hamid; Pogue, Brian W

2006-10-01

27

Breast implant has concave curved rear surface with different radii of curvature in transverse and saggital planes  

UK PubMed Central (United Kingdom)

The implant, made from a supple outer envelope (12) filled e.g. with silicone gel or a physiological serum, has a front surface (20) and a rear concave supporting surface (18) designed to be applied against the surface of a woman's thorax and having different radii of curvature in the transverse and saggital planes. The radius of curvature in the transverse plane is between 10 and 22 cm, and preferably 16 cm, while the radius of curvature in the saggital plane is between 20 and 40 cm and preferably 30 cm. In addition, the rear surface of the envelope is thicker than the front surface.

PEROUSE ERIC

28

Optical Phase-Space-Time-Frequency Tomography  

CERN Multimedia

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

29

Quantum optical coherence tomography with dispersion cancellation  

CERN Document Server

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

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

2002-01-01

30

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.

2006-01-01

31

Optical theorem, depolarization and vector tomography  

Energy Technology Data Exchange (ETDEWEB)

A law of the total flux conservation is formulated in the form of the optical theorem. It is employed to explicitly derive equations for the description of the neutron polarization within the range of the direct beam defined by its angular divergence. General considerations are illustrated by calculations using the Born and Eikonal approximations. Results are briefly discussed as applied to Larmor-Fourier tomography.

Toperverg, B.P

2003-07-01

32

Optical theorem, depolarization and vector tomography  

International Nuclear Information System (INIS)

A law of the total flux conservation is formulated in the form of the optical theorem. It is employed to explicitly derive equations for the description of the neutron polarization within the range of the direct beam defined by its angular divergence. General considerations are illustrated by calculations using the Born and Eikonal approximations. Results are briefly discussed as applied to Larmor-Fourier tomography.

2003-01-01

33

Acoustically penetrable optical reflector for photoacoustic tomography.  

UK PubMed Central (United Kingdom)

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.

Deng Z; Zhao H; Ren Q; Li C

2013-07-01

34

Optical coherence tomography in Barrett's esophagus.  

UK PubMed Central (United Kingdom)

The incidence of Barrett's-related adenocarcinoma of the esophagus continues to increase at an alarming rate. Studies to date show great promise for optical coherence tomography (OCT) in screening, surveillance, and guiding management of Barrett's esophagus. With continued innovation in rapid, accurate scanning systems, such as volumetric laser endomicroscopy or optical frequency domain imaging, advanced OCT seems likely to have an important impact. The next few years are likely to see the initiation of large clinical studies that will define the extent and significance of this impact.

Lightdale CJ

2013-07-01

35

Optical phase-space-time-frequency tomography.  

UK PubMed Central (United Kingdom)

We present a new approach for constructing optical phase-space-time-frequency tomography (OPSTFT) of an optical wave field. 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. Besides the distributions of x-p and t-?, the OPSTFT can provide four other distributions such as x-t, p-t, x-? and p-?. We simulate the OPSTFT for a light field obscured by a wire and a single-line absorption filter. We believe that the four-window system can provide spatial and temporal properties of a wave field for quantum image processing and biophotonics.

Rojas P; Blaser R; Sua YM; Lee KF

2011-04-01

36

Novel use of optical coherence tomography.  

UK PubMed Central (United Kingdom)

Currently in use by interventional cardiology for the intravascular evaluation of coronary arteries, optical coherence tomography (OCT) has proven to be effective in the evaluation of atherosclerotic disease and further therapeutic management. We report a novel use of OCT technology in the case of a 46-year-old man with sudden onset blurred vision and greater than 70% stenosis of his left vertebral artery. To date, no detailed descriptions or case reports have previously been reported regarding the use of neuroendovascular OCT in diseased arteries.

Patel IJ; Bezerra HG; Costa MA; Fujino Y; Hsu DP

2013-11-01

37

Novel use of optical coherence tomography.  

Science.gov (United States)

Currently in use by interventional cardiology for the intravascular evaluation of coronary arteries, optical coherence tomography (OCT) has proven to be effective in the evaluation of atherosclerotic disease and further therapeutic management. We report a novel use of OCT technology in the case of a 46-year-old man with sudden onset blurred vision and greater than 70% stenosis of his left vertebral artery. To date, no detailed descriptions or case reports have previously been reported regarding the use of neuroendovascular OCT in diseased arteries. PMID:23028109

Patel, Indravadan J; Bezerra, Hiram G; Costa, Marco A; Fujino, Yusuke; Hsu, Daniel P

2012-09-30

38

Rapid radial optical coherence tomography image acquisition.  

UK PubMed Central (United Kingdom)

We demonstrate how compressive sampling can be used to expedite volumetric optical coherence tomography (OCT) image acquisition. We propose a novel method to interpolate OCT volumetric images from data acquired by radial B-scans in the Cartesian coordinate system. Due to the inherent polar symmetry in the human eye, the (r, ?, z) coordinate system provides a natural domain to perform the interpolation. We demonstrate that the method has minimal effect on image quality even when up to 88% of the data is not acquired. The potential outcome of this work could lead to significant reductions in OCT volume acquisition time in clinical practice.

Lebed E; Lee S; Sarunic MV; Beg MF

2013-03-01

39

Optical coherence tomography in asteroid hyalosis.  

UK PubMed Central (United Kingdom)

PURPOSE: To demonstrate the clinical utility of optical coherence tomography (OCT) in diagnosing macular structural abnormalities in patients with asteroid hyalosis. METHODS: Case series. RESULTS: Seven eyes of seven patients underwent OCT due to inadequate funduscopic visualization secondary to asteroid hyalosis. Fluorescein angiography and B-scan ultrasonography were conducted for two patients but failed to provide diagnostic clarity. OCT provided definitive anatomical diagnoses that included macular epiretinal membrane, macular hole, traction retinal detachment, cystoid macular edema, and drusen. On the basis of OCT-assisted diagnoses, three patients elected to undergo surgical intervention. CONCLUSION: OCT can be critical to diagnose macular conditions when retinal visualization is limited by asteroid hyalosis.

Hwang JC; Barile GR; Schiff WM; Ober MD; Smith RT; Del Priore LV; Turano MR; Chang S

2006-07-01

40

Cartilage thickness measurements from optical coherence tomography  

Science.gov (United States)

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

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

2003-02-01

 
 
 
 
41

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

42

Cirrus high-definition optical coherence tomography compared with Stratus optical coherence tomography in glaucoma diagnosis  

Digital Repository Infrastructure Vision for European Research (DRIVER)

To compare the retinal nerve fiber layer (RNFL) evaluation using Cirrus optical coherence tomography (OCT) and Stratus OCT in glaucoma diagnosis. METHODS: One hundred thirty normal and 86 patients with glaucoma were included in this prospective study. The signal strengths of the O...

43

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

44

Adaptive wide-field optical tomography.  

Science.gov (United States)

We describe a wide-field optical tomography technique, which allows the measurement-guided optimization of illumination patterns for enhanced reconstruction performances. The iterative optimization of the excitation pattern aims at reducing the dynamic range in photons transmitted through biological tissue. It increases the number of measurements collected with high photon counts resulting in a dataset with improved tomographic information. Herein, this imaging technique is applied to time-resolved fluorescence molecular tomography for preclinical studies. First, the merit of this approach is tested by in silico studies in a synthetic small animal model for typical illumination patterns. Second, the applicability of this approach in tomographic imaging is validated in vitro using a small animal phantom with two fluorescent capillaries occluded by a highly absorbing inclusion. The simulation study demonstrates an improvement of signal transmitted (~2 orders of magnitude) through the central portion of the small animal model for all patterns considered. A corresponding improvement in the signal at the emission wavelength by 1.6 orders of magnitude demonstrates the applicability of this technique for fluorescence molecular tomography. The successful discrimination and localization (~1 mm error) of the two objects with higher resolution using the optimized patterns compared with nonoptimized illumination establishes the improvement in reconstruction performance when using this technique. PMID:23520659

Venugopal, Vivek; Intes, Xavier

2013-03-01

45

Adaptive wide-field optical tomography.  

UK PubMed Central (United Kingdom)

We describe a wide-field optical tomography technique, which allows the measurement-guided optimization of illumination patterns for enhanced reconstruction performances. The iterative optimization of the excitation pattern aims at reducing the dynamic range in photons transmitted through biological tissue. It increases the number of measurements collected with high photon counts resulting in a dataset with improved tomographic information. Herein, this imaging technique is applied to time-resolved fluorescence molecular tomography for preclinical studies. First, the merit of this approach is tested by in silico studies in a synthetic small animal model for typical illumination patterns. Second, the applicability of this approach in tomographic imaging is validated in vitro using a small animal phantom with two fluorescent capillaries occluded by a highly absorbing inclusion. The simulation study demonstrates an improvement of signal transmitted (?2 orders of magnitude) through the central portion of the small animal model for all patterns considered. A corresponding improvement in the signal at the emission wavelength by 1.6 orders of magnitude demonstrates the applicability of this technique for fluorescence molecular tomography. The successful discrimination and localization (?1??mm error) of the two objects with higher resolution using the optimized patterns compared with nonoptimized illumination establishes the improvement in reconstruction performance when using this technique.

Venugopal V; Intes X

2013-03-01

46

Adaptive wide-field optical tomography.  

UK PubMed Central (United Kingdom)

We describe a wide-field optical tomography technique, which allows the measurement-guided optimization of illumination patterns for enhanced reconstruction performances. The iterative optimization of the excitation pattern aims at reducing the dynamic range in photons transmitted through biological tissue. It increases the number of measurements collected with high photon counts resulting in a dataset with improved tomographic information. Herein, this imaging technique is applied to time-resolved fluorescence molecular tomography for preclinical studies. First, the merit of this approach is tested by in silico studies in a synthetic small animal model for typical illumination patterns. Second, the applicability of this approach in tomographic imaging is validated in vitro using a small animal phantom with two fluorescent capillaries occluded by a highly absorbing inclusion. The simulation study demonstrates an improvement of signal transmitted (~2 orders of magnitude) through the central portion of the small animal model for all patterns considered. A corresponding improvement in the signal at the emission wavelength by 1.6 orders of magnitude demonstrates the applicability of this technique for fluorescence molecular tomography. The successful discrimination and localization (~1 mm error) of the two objects with higher resolution using the optimized patterns compared with nonoptimized illumination establishes the improvement in reconstruction performance when using this technique.

Venugopal V; Intes X

2013-03-01

47

Optical coherence tomography: Technique and applications  

DEFF Research Database (Denmark)

Optical coherence tomography (OCT) is a noninvasive optical imaging modality providing real-time video rate images in two and three dimensions of biological tissues with micrometer resolution. OCT fills the gap between ultrasound and confocal microscopy, since it has a higher resolution than ultrasound and a higher penetration than confocal microcopy. Functional extensions are also possible, i.e., flow, birefringence or spectroscopic measurements with high spatial resolution. In ophthalmology, OCT is accepted as a clinical standard for diagnosing and monitoring the treatment of a number of retinal diseases. The potential of OCT in many other applications is currently being explored, such as in developmental biology, skin cancer diagnostics, vulnerable plaque detection in cardiology, esophageal diagnostics and a number of other applications within oncology.

Thomsen, Jakob Borup; Sander, Birgit

2009-01-01

48

[The role and value of optical coherence tomography in gynecology].  

Science.gov (United States)

Optical coherence tomography is one of the most important technological progress of the last ten years in the field of medical imaging. It is similar to ultrasound imaging except that it uses properties of light instead of ultrasound. Optical coherence tomography provides images of tissue structure, and at a cellular level, in situ, in real time, with much better spatial resolution than ultrasound and without removal of tissue (optical biopsy). Using optical coherence tomography in combination with catheters or endoscopes may enable the imaging of internal organs as the cervix, the uterine tissue and the ovary. The use of optical coherence tomography in the gynecological field is still experimental and is mainly about the in vitro and in vivo diagnosis of cervical dysplasia, cervical cancer, ovary cancer, endometrial cancer and endometriosis. We aim to present the principles of optical coherence tomography and to expose the main ways of research and the future and potential clinical applications of this technique in gynecology. PMID:17822859

Ascencio, M; Collinet, P; Cosson, M; Mordon, S

2007-09-05

49

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)

2006-02-28

50

Optical tomography of the aurora and EISCAT  

Directory of Open Access Journals (Sweden)

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

H. U. Frey; S. Frey; B. S. Lanchester; M. Kosch

0000-01-01

51

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.

2006-01-01

52

Advanced modelling of optical coherence tomography systems  

Energy Technology Data Exchange (ETDEWEB)

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.

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

2004-04-07

53

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

2006-01-01

54

Varnish Ablation Control by Optical Coherence Tomography  

International Nuclear Information System (INIS)

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.

2006-01-01

55

Contrast-enhanced intraoperative optical coherence tomography.  

UK PubMed Central (United Kingdom)

Optical coherence tomography (OCT) has revolutionised clinical ophthalmology. The translation of OCT into the operating room is a natural next step given its high-resolution anatomic information. Contrast agents and enhancement have significantly improved the diagnostic capabilities of numerous imaging modalities (such as CT and MRI). The use of OCT contrast agents in ophthalmology has been generally lacking. In this report, we describe the novel application of triamcinolone as an OCT contrast agent for intraoperative OCT to improve visibility of tissue interfaces and planes (eg, posterior hyaloid insertion points). The application of this technology may have wide-ranging implications for enhanced image-guided surgery, intraoperative OCT and dynamic or functional applications of OCT technology.

Ehlers JP; McNutt SA; Kaiser PK; Srivastava SK

2013-04-01

56

Advanced modelling of optical coherence tomography systems  

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 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.

Andersen, Peter E.; Thrane, L.

2004-01-01

57

Target detection and characterization using a hybrid handheld diffuse optical tomography and photoacoustic tomography system  

Science.gov (United States)

A handheld photoacoustic tomography-guided diffuse optical tomography system for imaging deeply-seated targets in scattering media is presented. This hybrid imager consists of a probe with an ultrasound transducer in the center and straddled by two optical fibers for taking photoacoustic images. The diffuse optical tomography component comprises of 9 light-source fibers for delivering light to the imaged tissue, and 14 detector fibers for collecting the light. Single- and two-phantom targets of high and low optical contrasts were immersed in a scattering intralipid solution to depths of up to 3cm and imaged. The reconstructed absorption coefficients of the targets with guidance from photoacoustic tomography were compared to those obtained with a-priori depth-only information, and no a-priori information. The reconstructed absorption maps yielded as much as 2.6-fold improvement in the quantification accuracy compared to the cases with no guidance from photoacoustic tomography.

Kumavor, Patrick D.; Aguirre, Andres; Xu, Chen; Gamelin, John; Ardeshirpour, Yasaman; Tavakoli, Behnoosh; Zanganeh, Saeid; Alqasemi, Umar S.; Zhu, Quing

2011-02-01

58

Optical coherence tomography for endodontic imaging  

Science.gov (United States)

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

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

2008-03-01

59

[Comparison of Heidelberg retinal tomography and spectral domain optical coherence tomography examinations for detection of glaucoma].  

UK PubMed Central (United Kingdom)

PURPOSE: To compare the diagnostic ability of Heidelberg Retina Tomograph 3 and Spectral Domain Optical Coherence Tomography Copernicus in detection of optic disc changes in glaucomatous patients. MATERIAL AND METHODS: Retrospective analysis of 24 eyes of 24 subjects with primary open angle glaucoma. All individuals had complete ophthalmic examination, Heidelberg Retina Tomograph 3 and Spectral Domain Optical Coherence Tomography examinations performed. Measurements in Spectral Domain Optical Coherence Tomography were obtained both automatically (Spectral Domain Optical Coherence Tomography software) and manually. Following diameters were analyzed: disc area, cup area, cup volume, C to D ratio (C/D ratio) and circumpapillary retinal nerve fiber layer thickness. RESULTS: Disc area, cup area, cup volume were classified as within normal limits more often in Spectral Domain Optical Coherence Tomography printouts than in Heidelberg Retina Tomograph (75%, 63% and 83% in SD-OCT auto, 70%, 57% and 83% in SD-OCT manu vs. 58%, 37% and 33% in Heidelberg Retina Tomograph, respectively). C/D ratio was increased in 23 eyes (96%) in Heidelberg Retina Tomograph compared to 14 eyes (58%) in SD-OCT auto and 12 eyes (52%) in SD-OCT manu. Retinal nerve fiber layer thickness was significantly lower in Spectral Domain Optical Coherence Tomography (both auto and manu 96% vs. 58% in Heidelberg Retina Tomograph). According to the Moorfields Regresion Analysis classification from Heidelberg Retina Tomograph, 21 eyes were diagnosed as glaucomatous (88%). CONCLUSIONS: Although there was poor agreement in optic disc measurements between the two methods, both had high sensitivity in detection of glaucomatous optic disc changes (96% when retinal nerve fiber layer thickness measured by Spectral Domain Optical Coherence Tomography compared to 88% for Moorfield regresion analysis in Heidelberg Retina Tomograph). The sensitivity of diagnostic ability increases when both, Heidelberg Retina Tomograph and Spectral Domain Optical Coherence Tomography are performed.

Piasecka K; Bednarski M; Nawrocka Z; Nawrocki J; Michalewska Z

2013-01-01

60

In vivo endoscopic multi-beam optical coherence tomography  

International Nuclear Information System (INIS)

A multichannel optical coherence tomography (multi-beam OCT) system and an in vivo endoscopic imaging probe were developed using a swept-source OCT system. The distal optics were micro-machined to produce a high numerical aperture, multi-focus fibre optic array. This combination resulted in a transverse design resolution of

2010-02-07

 
 
 
 
61

Optic canal location by computed tomography.  

Science.gov (United States)

The aim of this study was to provide anatomic data for optic canal decompression. One hundred twenty people (55 males and 65 females) were involved in this study anonymously. Twelve parameters are measured in computed tomography: P1 is the nasal bone tip; P2 is the middle point of tuberculum sellae; P3 is the root of columella nasi; P4 is the cranium end of the optic canal; P5 is the orbit end of the optic canal; P1' is P1's projection on L2; L1 is the line that links P1 and P2; L2 goes through P3 and parallel to L1; L3 is the bisector of right and left and goes through P1. The distance between LI and L2 was 30.47 ± 3.71 mm. The distance between P3 and P1' was 11.66 ± 2.82 mm. The medial canal wall length was 10.64 ± 1.10 mm on the right and 10.51 ± 1.07 mm on the left (P = 0.001). The distance between P1 and P4 was 66.74 ± 5.97 mm. The distance between P1 and P5 was 73.04 ± 6.33 mm on the right and 72.82 ± 6.33 mm on the left (P = 0.004). The distance between P5 and L3 was 6.62 ± 1.33 mm. The distance between P4 and L3 was 12.26 ± 1.63 mm. The distance between P3 and P4 was 75.82 ± 4.63 mm. The distance between P3 and P5 was 82.87 ± 4.60 mm on the right and 82.25 ± 4.86 mm on the left (P = 0.003). The angle between P1P4 and L3 was 12.26 ± 1.63 degrees. The angle between P1P5 and L3 was 5.28 ± 1.13 degrees. The angle between P3P5 and P3P4 was 5.80 ± 0.97 degrees. These results provide a precise location of the optic canal. PMID:23348301

Liu, Shuaichen; Chen, Yu; Song, Junxue; Tian, Yong; Xia, Changli; Li, Youqiong

2013-01-01

62

Optic canal location by computed tomography.  

UK PubMed Central (United Kingdom)

The aim of this study was to provide anatomic data for optic canal decompression. One hundred twenty people (55 males and 65 females) were involved in this study anonymously. Twelve parameters are measured in computed tomography: P1 is the nasal bone tip; P2 is the middle point of tuberculum sellae; P3 is the root of columella nasi; P4 is the cranium end of the optic canal; P5 is the orbit end of the optic canal; P1' is P1's projection on L2; L1 is the line that links P1 and P2; L2 goes through P3 and parallel to L1; L3 is the bisector of right and left and goes through P1. The distance between LI and L2 was 30.47 ± 3.71 mm. The distance between P3 and P1' was 11.66 ± 2.82 mm. The medial canal wall length was 10.64 ± 1.10 mm on the right and 10.51 ± 1.07 mm on the left (P = 0.001). The distance between P1 and P4 was 66.74 ± 5.97 mm. The distance between P1 and P5 was 73.04 ± 6.33 mm on the right and 72.82 ± 6.33 mm on the left (P = 0.004). The distance between P5 and L3 was 6.62 ± 1.33 mm. The distance between P4 and L3 was 12.26 ± 1.63 mm. The distance between P3 and P4 was 75.82 ± 4.63 mm. The distance between P3 and P5 was 82.87 ± 4.60 mm on the right and 82.25 ± 4.86 mm on the left (P = 0.003). The angle between P1P4 and L3 was 12.26 ± 1.63 degrees. The angle between P1P5 and L3 was 5.28 ± 1.13 degrees. The angle between P3P5 and P3P4 was 5.80 ± 0.97 degrees. These results provide a precise location of the optic canal.

Liu S; Chen Y; Song J; Tian Y; Xia C; Li Y

2013-01-01

63

Integrated-optics-based swept-source optical coherence tomography.  

Science.gov (United States)

We designed, fabricated, and characterized an integrated-optics-based swept-source optical coherence tomography (SS-OCT) system in TriPleX technology. An external 1300 nm swept source is coupled to the chip, which contains waveguide structures for interferometric depth ranging and balanced detection. The complete OCT chip has a footprint of 0.4 cm × 1.8 cm. Light from the chip is focused onto the sample using an aspheric lens; the lateral resolution is 21±1 ?m. OCT measurements, performed with a moveable mirror, demonstrate a sensitivity of -80 dB and imaging up to the maximum depth of 5.09 mm. Corrected for dispersion, the measured OCT axial resolution of 12.7±0.5 ?m is in good agreement with the bandwidth limited resolution. Finally, we demonstrate cross-sectional OCT imaging of a multilayered tissue phantom over the whole depth range with the integrated-optics-based SS-OCT system. PMID:23202057

Nguyen, V Duc; Weiss, N; Beeker, W; Hoekman, M; Leinse, A; Heideman, R G; van Leeuwen, T G; Kalkman, J

2012-12-01

64

Integrated-optics-based swept-source optical coherence tomography.  

UK PubMed Central (United Kingdom)

We designed, fabricated, and characterized an integrated-optics-based swept-source optical coherence tomography (SS-OCT) system in TriPleX technology. An external 1300 nm swept source is coupled to the chip, which contains waveguide structures for interferometric depth ranging and balanced detection. The complete OCT chip has a footprint of 0.4 cm × 1.8 cm. Light from the chip is focused onto the sample using an aspheric lens; the lateral resolution is 21±1 ?m. OCT measurements, performed with a moveable mirror, demonstrate a sensitivity of -80 dB and imaging up to the maximum depth of 5.09 mm. Corrected for dispersion, the measured OCT axial resolution of 12.7±0.5 ?m is in good agreement with the bandwidth limited resolution. Finally, we demonstrate cross-sectional OCT imaging of a multilayered tissue phantom over the whole depth range with the integrated-optics-based SS-OCT system.

Nguyen VD; Weiss N; Beeker W; Hoekman M; Leinse A; Heideman RG; van Leeuwen TG; Kalkman J

2012-12-01

65

Advanced Technologies for Ultrahigh Resolution and Functional Optical Coherence Tomography.  

Science.gov (United States)

This program, entitled Advanced Technologies for Structural and Functional Optical Coherence Tomography, is a collaborative effort between investigators at the Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Scienc...

J. G. Fujimoto

2008-01-01

66

Optical Coherence Tomography and Raman Spectroscopy of the Retina.  

Science.gov (United States)

Imaging the structure and correlating it with the biochemical content of the retina holds promise for fundamental research and for clinical applications. Optical coherence tomography (OCT) is commonly used to image the 3D structure of the retina and while...

J. Chan J. S. Werner J. W. Evans R. Liu R. J. Zawadzki S. Lane

2009-01-01

67

[Aspects of optical coherence tomography in diabetic retinopathy].  

UK PubMed Central (United Kingdom)

Optical coherence tomography is a new and very useful technique for diabetic patients. It is used to determine the early changes in diabetic retinopathy and to help the ophthalmologist to choose the appropriate therapy.

Gafencu O; Buliga S

2004-01-01

68

Optical coherence tomography in vulvar intraepithelial neoplasia  

Science.gov (United States)

Vulvar squamous cell carcinoma (VSCC) is a gynecological cancer with an incidence of two to three per 100,000 women. VSCC arises from vulvar intraepithelial neoplasia (VIN), which is diagnosed through painful punch biopsy. In this study, optical coherence tomography (OCT) is used to differentiate between normal and VIN tissue. We hypothesize that (a) epidermal layer thickness measured in OCT images is different in normal tissue and VIN, and (b) quantitative analysis of the attenuation coefficient (?oct) extracted from OCT data differentiates VIN from normal vulvar tissue. Twenty lesions from 16 patients are imaged with OCT. Directly after data acquisition, a biopsy is performed. Epidermal thickness is measured and values of ?oct are extracted from 200 OCT scans of normal and VIN tissue. For both methods, statistical analysis is performed using Paired Mann-Whitney-test. Correlation between the two methods is tested using a Spearman-correlation test. Both epidermal layer thickness as well as the ?oct are different between normal vulvar tissue and VIN lesions (p<0.0001). Moreover, no correlation is found between the epidermal layer thickness and ?oct. This study demonstrates that both the epidermal thickness and the attenuation coefficient of vulvar epithelial tissue containing VIN are different from that of normal vulvar tissue.

Wessels, Ronni; de Bruin, Daniel M.; Faber, Dirk J.; van Boven, Hester H.; Vincent, Andrew D.; van Leeuwen, Ton G.; van Beurden, Marc; Ruers, Theo J. M.

2012-11-01

69

Optical coherence tomography in vulvar intraepithelial neoplasia.  

UK PubMed Central (United Kingdom)

Vulvar squamous cell carcinoma (VSCC) is a gynecological cancer with an incidence of two to three per 100,000 women. VSCC arises from vulvar intraepithelial neoplasia (VIN), which is diagnosed through painful punch biopsy. In this study, optical coherence tomography (OCT) is used to differentiate between normal and VIN tissue. We hypothesize that (a) epidermal layer thickness measured in OCT images is different in normal tissue and VIN, and (b) quantitative analysis of the attenuation coefficient (?oct) extracted from OCT data differentiates VIN from normal vulvar tissue. Twenty lesions from 16 patients are imaged with OCT. Directly after data acquisition, a biopsy is performed. Epidermal thickness is measured and values of ?oct are extracted from 200 OCT scans of normal and VIN tissue. For both methods, statistical analysis is performed using Paired Mann-Whitney-test. Correlation between the two methods is tested using a Spearman-correlation test. Both epidermal layer thickness as well as the ?oct are different between normal vulvar tissue and VIN lesions (p < 0.0001). Moreover, no correlation is found between the epidermal layer thickness and ?oct. This study demonstrates that both the epidermal thickness and the attenuation coefficient of vulvar epithelial tissue containing VIN are different from that of normal vulvar tissue.

Wessels R; de Bruin DM; Faber DJ; van Boven HH; Vincent AD; van Leeuwen TG; van Beurden M; Ruers TJ

2012-11-01

70

Stent evaluation with optical coherence tomography.  

UK PubMed Central (United Kingdom)

Optical coherence tomography (OCT) has been recently applied to investigate coronary artery disease in interventional cardiology. Compared to intravascular ultrasound, OCT is able to visualize various vascular structures more clearly with higher resolution. Several validation studies have shown that OCT is more accurate in evaluating neointimal tissue after coronary stent implantation than intravascular ultrasound. Novel findings on OCT evaluation include the detection of strut coverage and the characterization of neointimal tissue in an in-vivo setting. In a previous study, neointimal healing of stent strut was pathologically the most important factor associated with stent thrombosis, a fatal complication, in patients treated with drug-eluting stent (DES). Recently, OCT-defined coverage of a stent strut was proposed to be related with clinical safety in DES-treated patients. Neoatherosclerosis is an atheromatous change of neointimal tissue within the stented segment. Clinical studies using OCT revealed neoatherosclerosis contributed to late-phase luminal narrowing after stent implantation. Like de novo native coronary lesions, the clinical presentation of OCT-derived neoatherosclerosis varied from stable angina to acute coronary syndrome including late stent thrombosis. Thus, early identification of neoatherosclerosis with OCT may predict clinical deterioration in patients treated with coronary stent. Additionally, intravascular OCT evaluation provides additive information about the performance of coronary stent. In the near future, new advances in OCT technology will help reduce complications with stent therapy and accelerating in the study of interventional cardiology.

Lee SY; Hong MK

2013-09-01

71

Carious growth monitoring with optical coherence tomography  

Science.gov (United States)

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

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

2006-03-01

72

Capabilities of optical coherence tomography in laryngology  

Science.gov (United States)

We present first result of using the optical coherence tomography (OCT) in complex clinical studies in laryngology. Mucosa of the upper and middle portions of larynx is of special interest for OCT applications: it is clinically important, easily accessed by an endoscopic OCT probe, and possesses a well defined and rich tomographic structure. We have examined several tens of patients with abnormalities in vocal folds. The diagnosis was made based on clinical data including laryngoscopy and finally confirmed morphologically. When examining larynx mucosa, an endoscopic OCT probe has been introduced through a standard laryngoscope lumen, so that OCT imaging has been performed in parallel with visual observation. The OCT studies have demonstrated that in comparison with stratified healthy mucosa, carcinomatous regions have no tomographically differentiated structure, thus allowing one to exactly define the border of a tumor. Vocal nodules are imaged as poorly scattering regions without clear boundaries under preserved epithelium. Cysts of gland mucosa are seen with OCT as sharply delineated shadows at the depth of several hundred micrometers. We have also examined several patients with carcinoma after a course of radiation therapy and observed different changes in OCT images of adjoining epithelium corresponding to metaplasia, hyperplasia, and sclerosis.

Shakhov, Andrei; Terentjeva, Anna; Gladkova, Natalia D.; Snopova, Ludmila; Chumakov, Yuri; Feldchtein, Felix I.; Gelikonov, Valentin M.; Gelikonov, Grigory V.; Sergeev, Alexander M.

1999-06-01

73

Space-division multiplexing optical coherence tomography.  

UK PubMed Central (United Kingdom)

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

Zhou C; Alex A; Rasakanthan J; Ma Y

2013-08-01

74

Polarization sensitive optical coherence tomography detection method  

Energy Technology Data Exchange (ETDEWEB)

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

75

Optical coherence tomography of central serous chorioretinopathy  

Directory of Open Access Journals (Sweden)

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

Feng Yan; Kai Meng; Bao-Cheng Men; Dan Liu

2013-01-01

76

Imaging granulomatous lesions with optical coherence tomography.  

UK PubMed Central (United Kingdom)

AIM: To investigate and compare the presentation of granulomatous lesions in optical coherence tomography (OCT) images and compare this to previous studies of nonmelanoma skin tumors. METHODS: Two patients with granulomas, tophi and granuloma annulare (GA), respectively, were photographed digitally, OCT-scanned and biopsied in the said order. Normal skin was OCT-scanned for comparison, but not biopsied. The OCT images from each lesion were compared with their histologic images as well as with OCT images with similar characteristics obtained from nonmelanoma skin tumors. RESULTS: The OCT images of the tophi showed hyperreflective, rounded cloud-like structures in dermis, their upper part sharply delineated by a hyporeflective fringe. The deeper areas appeared blurred. The crystalline structures were delineated by a hyporeflective fringe. OCT images of GA showed two different structures in dermis: a hyporeflective rounded one, and one that was lobulated and wing-like. CONCLUSION: Granulomatous tissue surrounding urate deposits appeared as a clear hyporeflective fringe surrounding a light, hyperreflective area. The urate crystals appeared as hyperreflective areas, shielding the deeper part of dermis, meaning OCT could only visualize the upper part of the lesions. The lobulated, wing-like structure in GA may resemble diffuse GA or a dense lymphocytic infiltrate as seen on histology. The rounded structure in GA may represent an actual granuloma or either diffuse GA or a dense lymphocytic infiltrate as described above. This case suggests that OCT images granulomatous tissue as absorbent, hyporeflective areas, and urate crystals appear as reflective areas, obscuring the underlying tissue. In GA a new image shape looking like a wing has been found. The frequency, specificity and sensitivity of this new pattern in OCT imaging will require further studies.

Banzhaf C; Jemec GB

2012-01-01

77

Three dimensional time reversal optical tomography  

Science.gov (United States)

Time reversal optical tomography (TROT) approach is used to detect and locate absorptive targets embedded in a highly scattering turbid medium to assess its potential in breast cancer detection. TROT experimental arrangement uses multi-source probing and multi-detector signal acquisition and Multiple-Signal-Classification (MUSIC) algorithm for target location retrieval. Light transport from multiple sources through the intervening medium with embedded targets to the detectors is represented by a response matrix constructed using experimental data. A TR matrix is formed by multiplying the response matrix by its transpose. The eigenvectors with leading non-zero eigenvalues of the TR matrix correspond to embedded objects. The approach was used to: (a) obtain the location and spatial resolution of an absorptive target as a function of its axial position between the source and detector planes; and (b) study variation in spatial resolution of two targets at the same axial position but different lateral positions. The target(s) were glass sphere(s) of diameter ~9 mm filled with ink (absorber) embedded in a 60 mm-thick slab of Intralipid-20% suspension in water with an absorption coefficient ?a ~ 0.003 mm-1 and a transport mean free path lt ~ 1 mm at 790 nm, which emulate the average values of those parameters for human breast tissue. The spatial resolution and accuracy of target location depended on axial position, and target contrast relative to the background. Both the targets could be resolved and located even when they were only 4-mm apart. The TROT approach is fast, accurate, and has the potential to be useful in breast cancer detection and localization.

Wu, Binlin; Cai, W.; Alrubaiee, M.; Xu, M.; Gayen, S. K.

2011-02-01

78

Optical Coherence Tomography of the Breast: A Feasibility Study.  

Science.gov (United States)

Optical Coherence Tomography (OCT) is an emerging high-resolution imaging technology that can perform high resolution, real-time cross-sectional imaging of tissue. OCT can be used as a type of "optical biopsy to perform minimally-invasive imaging up ...

J. L. Connolly

2005-01-01

79

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 identi...

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

80

Quantum optical coherence tomography of a biological sample  

CERN Multimedia

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

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

2008-01-01

 
 
 
 
81

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

82

[Optical coherence tomography imaging in commotio retinae: case report].  

UK PubMed Central (United Kingdom)

The purpose of this case report was to correlate optical coherence tomography findings and visual outcomes of patients with different degrees of commotio retinae. A 20-year-old male and a 23-year-old male that presented with decreased vision due to Berlin's edema after blunt ocular trauma were evaluated by optical coherence tomography and retinography. The visual acuity in the affected eye was 20/25 in the first patient and counting fingers in the second one. The ophthalmic examination showed traumatic uveitis and fundoscopy revealed mild retinal opacification in the first case and severe opacification in the latter. The optical coherence tomography confirmed the reduction of foveal depression on the first case and the disarrangement of all retinal layers on the second. There has been complete functional and anatomical resolution by optical coherence tomography in the first patient, while the second evolved to permanent visual loss. Optical coherence tomography is a useful method in the evaluation of retinal trauma, helping to understand its physiopathology and to predict its prognosis through the anatomical analysis of the affected region.

Morita C; Preti RC; Ferraz DA; Maia OO Jr; Takahashi WY

2009-07-01

83

Adaptive optical probe design for optical coherence tomography and microscopy using tunable optics.  

UK PubMed Central (United Kingdom)

We present a tunable, adaptive optical imaging probe for multimodal imaging such as optical coherence tomography and microscopy. The probe is compatible with forward-looking scanning laser imaging devices such as an endoscope. The lens configuration includes a tunable iris and two varifocal lenses, both driven by microelectrofluidics, as well as several conventional fixed focus lenses. The modulation transfer function and spot size in the focal plane is evaluated, and we show using optical simulations that there are three possible imaging modes with different transverse resolutions and focal depths.

Choi M; Lee S; Chang JH; Lee E; Jung KD; Kim W

2013-01-01

84

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

2004-01-01

85

[Applications of Optical Coherence Tomography (OCT) in Neuro-ophthalmology.  

UK PubMed Central (United Kingdom)

Optical coherence tomography (OCT) has revolutionised ophthalmology. Due to modern instruments with extremely high resolution there are more and more applications also in neuro-ophthalmological disorders. This review gives an overview on typical changes in OCT for the following diseases: autosomal dominant optic atrophy, Leber hereditary optic neuropathy, toxic, traumatic and compressive optic neuropathy, optic nerve drusen, anterior ischaemic optic neuropathy, optic disc pit, papilledema, optic neuritis (isolated or associated with multiple sclerosis or neuromyelitis optica), neurodegenerative diseases and hereditary retinal diseases. A diagnosis exclusively based on an OCT examination is not always possible, but in several diseases there are pathognomonic changes that directly lead to the correct diagnosis. Particularly with the often complex settings in neuro-ophtalmology the OCT should be seen as a supplementary modality and not as a replacement for other techniques.

Kernstock C; Friebe K; Tonagel F

2013-09-01

86

[Optical coherence tomography aspects of sympathetic ophthalmia: case report].  

UK PubMed Central (United Kingdom)

The sympathetic ophthalmia is a granulomatous panuveitis that starts after ocular trauma. The prognosis is poor and depends of both early diagnosis and treatment. The authors describe one case of a patient with sympathetic ophthalmia using optical coherence tomography who was submitted to early treatment, and it suggests that the optical coherence tomography can corroborate as a ancillary method in the study of retina characteristics in sympathetic ophthalmia disease specially in cases of rare presentation, with serous retinal detachment as an isolated ophthalmological manifestation.

Ferreira MA; Mendonça CN; Sá Filho WF; Neves AS

2009-05-01

87

Optical coherence tomography in spontaneous resolution of vitreomacular traction syndrome.  

UK PubMed Central (United Kingdom)

Vitreomacular traction syndrome (VTS) is a vitreoretinal interface abnormality. The disorder is caused by incomplete posterior vitreous detachment with persistent traction on the macula that produces symptoms and decreased vision. Most symptomatic eyes with VTS undergo a further decrease in visual acuity. Spontaneous complete vitreomacular separation occurs infrequently in eyes with VTS. Surgical intervention may be considered if severe metamorphopsia and decreased visual quality occur. Herein, we report 2 typical cases of idiopathic VTS with spontaneous resolution of vitreo-retinal traction demonstrated by optical coherence tomography. Optical coherence tomography is a sensitive and useful tool for the confirmation of diagnosis and for the serial anatomical evaluation of patients with VTS.

Hung KH; Yang CS; Lin TC; Lee FL; Lee SM

2010-06-01

88

Optical coherence tomography in spontaneous resolution of vitreomacular traction syndrome.  

Science.gov (United States)

Vitreomacular traction syndrome (VTS) is a vitreoretinal interface abnormality. The disorder is caused by incomplete posterior vitreous detachment with persistent traction on the macula that produces symptoms and decreased vision. Most symptomatic eyes with VTS undergo a further decrease in visual acuity. Spontaneous complete vitreomacular separation occurs infrequently in eyes with VTS. Surgical intervention may be considered if severe metamorphopsia and decreased visual quality occur. Herein, we report 2 typical cases of idiopathic VTS with spontaneous resolution of vitreo-retinal traction demonstrated by optical coherence tomography. Optical coherence tomography is a sensitive and useful tool for the confirmation of diagnosis and for the serial anatomical evaluation of patients with VTS. PMID:20603094

Hung, Kuo-Hsuan; Yang, Chang-Sue; Lin, Tai-Chi; Lee, Feng-Lih; Lee, Shui-Mei

2010-06-01

89

Optical coherence tomography in x-linked adrenoleukodystrophy.  

UK PubMed Central (United Kingdom)

BACKGROUND: X-linked adrenoleukodystrophy is a metabolic disease caused by mutations in the ABCD1 gene, which codes for a peroxisomal membrane protein, leading to the accumulation of very long-chain fatty acids. Thinning of the retinal nerve fiber layer and macula has been described in adult-onset adrenomyeloneuropathy; however, assessment of these structures in the presymptomatic stage remains largely unexplored. Optical coherence tomography is a high-resolution medical imaging technology that has been widely used to assess ophthalmological diseases and more recently in neurological disease states to quantify the axonal and neuronal injury in the retina that results from demyelination of the optic nerve. METHODS: Fourteen boys with presymptomatic X-linked adrenoleukodystrophy and 14 age-matched healthy controls underwent retinal imaging with optical coherence tomography. RESULTS: Optical coherence tomography-derived retinal thickness measures did not differ between adrenoleukodystrophy subjects and healthy controls. CONCLUSIONS: Our results suggest that structural retinal abnormalities are not detectable before the development of neurological manifestations in adrenoleukodystrophy. Further investigation of the utility of optical coherence tomography scanning in individuals with symptomatic disease should be considered to determine if its measures could be used as a biomarker of disease progression.

Aquino JJ; Sotirchos ES; Saidha S; Raymond GV; Calabresi PA

2013-09-01

90

Frequency multiplexed long range swept source optical coherence tomography.  

UK PubMed Central (United Kingdom)

We present a novel swept source optical coherence tomography configuration, equipped with acousto-optic deflectors that can be used to simultaneously acquire multiple B-scans originating from different depths. The sensitivity range of the configuration is evaluated while acquiring five simultaneous B-scans. Then the configuration is employed to demonstrate long range B-scan imaging by combining two simultaneous B-scans from a mouse head sample.

Zurauskas M; Bradu A; Podoleanu AG

2013-06-01

91

Subluxed traumatic cataract: optical coherence tomography findings and clinical management  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Ajay E Kuriyan, Harry W Flynn Jr, Sonia H YooDepartment of Ophthalmology, Bascom Palmer Eye Institute, University of Miami, Miami, FLAbstract: This case report describes the optical coherence tomography (OCT) findings and clinical management of a patient with traumatic subluxed cataract. The patien...

Kuriyan AE; Flynn Jr HW; Yoo SH

92

Volumetric quantification of fibrous caps using intravascular optical coherence tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The rupture of thin-cap fibroatheroma accounts for most acute coronary events. Optical Coherence Tomography (OCT) allows quantification of fibrous cap (FC) thickness in vivo. Conventional manual analysis, by visually determining the thinnest part of the FC is subject to inter-observer variability an...

Wang, Zhao; Chamie, Daniel; Bezerra, Hiram G.; Yamamoto, Hirosada; Kanovsky, Jan; Wilson, David L.; Costa, Marco A.

93

Anatomical atlas-guided diffuse optical tomography of brain activation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We describe a neuroimaging 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 obta...

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

94

3D optical tomography in the presence of void regions  

Science.gov (United States)

We present an investigation of the effect of a 3D non-scattering gap region on image reconstruction in diffuse optical tomography. The void gap is modelled by the Radiosity-Diffusion method and the inverse problem is solved using the adjoint field method. The case of a sphere with concentric spherical gap is used as an example.

Riley, J.; Dehghani, Hamid; Schweiger, Martin; Arridge, Simon R.; Ripoll, Jorge; Nieto-Vesperinas, Manuel

2000-12-01

95

3D optical tomography in the presence of void regions.  

UK PubMed Central (United Kingdom)

We present an investigation of the effect of a 3D non-scattering gap region on image reconstruction in diffuse optical tomography. The void gap is modelled by the Radiosity-Diffusion method and the inverse problem is solved using the adjoint field method. The case of a sphere with concentric spherical gap is used as an example.

Riley J; Dehghani H; Schweiger M; Arridge S; Ripoll J; Nieto-Vesperinas M

2000-12-01

96

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 dat...

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

97

Optical coherence tomography: a new method to assess aneurysm healing.  

UK PubMed Central (United Kingdom)

OBJECT: Aneurysmal subarachnoid hemorrhage affects approximately 10/100,000 people per year. Endovascular coil embolization is used increasingly to treat cerebral aneurysms and its safety and durability is rapidly developing. The long-term durability of coil embolization of cerebral aneurysms remains in question; patients treated using this modality require multiple follow-up angiography studies and occasional repeated treatments. METHODS: Optical coherence tomography (OCT) is an emerging imaging modality that uses backscattered light to produce high-resolution tomography of optically accessible biological tissues such as the eye, luminal surface of blood vessels, and gastrointestinal tract. Vascular OCT probes in the form of imaging microwires are presently available--although not Food and Drug Administration-approved--and may be adapted for use in the cerebral circulation. In this study the authors describe the initial use of OCT to make visible the neck of aneurysms created in a canine model and treated with coil embolization. Optical coherence tomography images demonstrate changes that correlate with the histological findings of healing at the aneurysm neck and thus may be capable of demonstrating human cerebral aneurysm healing. CONCLUSIONS: Optical coherence tomography may obviate the need for subsequent follow-up angiography studies as well as aid in the understanding of endovascular tissue healing. Data in this study demonstrate that further investigation of in vivo imaging with such probes is warranted.

Thorell WE; Chow MM; Prayson RA; Shure MA; Jeon SW; Huang D; Zeynalov E; Woo HH; Rasmussen PA; Rollins AM; Masaryk TJ

2005-02-01

98

Ultrasound induced improvement in optical coherence tomography (OCT) resolution  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Optical coherence tomography (OCT) is a rapidly emerging technology for high-resolution biomedical imaging. The axial resolution of this technology is determined by the bandwidth of the source. Commercial sources generally provide resolutions of 10–20 ?m whereas laboratory-based solid state lasers h...

Schenk, John O.; Brezinski, Mark E.

99

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

Directory of Open Access Journals (Sweden)

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

Michael F Joseph; Craig R Denegar; Elaine Horn; et al

2010-01-01

100

Fibrin phantom for use in optical coherence tomography  

Science.gov (United States)

This work presents a novel tissue-mimicking phantom for use in a range of optical coherence tomography (OCT) experiments. Such phantoms are critical in the development and assessment of new OCT techniques, but no previously published phantoms have become universally accepted. We present the first description of a phantom based on a fibrin matrix, which improves key attributes of previously published methods. It provides a biocompatible, optically transparent scaffold in which to incorporate organic and/or inorganic optical scattering materials. Its fabrication time is markedly shorter than many common phantoms, and its lifetime is longer than other biocompatible phantoms. The potential of fibrin phantoms incorporating Intralipid™ to introduce uniform optical scattering is demonstrated. The measured attenuation coefficient as a function of Intralipid concentration confirms the ability to control optical scattering. A bilayer phantom with distinct optical scattering in each layer is also presented.

Kennedy, Brendan F.; Loitsch, Susanne; McLaughlin, Robert A.; Scolaro, Loretta; Rigby, Paul; Sampson, David D.

2010-05-01

 
 
 
 
101

Comparison of Heidelberg retina tomography, optical coherence tomography and Humphrey visual field in early glaucoma diagnosis.  

UK PubMed Central (United Kingdom)

OBJECTIVE: To determine the value of optic disc parameters and perimetric defects in the early diagnosis of patients with primary open-angle glaucoma (POAG). METHODS: Optic disc parameters and perimetry were compared among patients in the early stage of POAG, patients with suspected POAG and healthy control subjects, using Heidelberg retina tomography (HRT-II), optical coherence tomography (OCT) and a Humphrey 750i automatic field analyser, in order to determine whether these parameters could be used for early POAG diagnosis. RESULTS: A total of 55 participants were enrolled in the study. Significant differences in the optic disc parameter and perimetry values were observed between the three groups. HRT-II parameters showed good correlation with OCT parameters. The majority of the HRT-II and OCT parameters showed a good correlation with perimetry values. CONCLUSIONS: HRT-II and OCT optic disc parameters both reflect morphological changes of the optic disc. These current findings suggest that they can both detect glaucomatous optic neuropathy earlier than a white-on-white perimetry examination. In addition, OCT can detect optic disc parameter changes that cannot be detected by HRT-II.

Wang H; Tao Y; Sun XL; Zhuang K

2013-10-01

102

Visible-light optical coherence tomography for retinal oximetry.  

UK PubMed Central (United Kingdom)

We applied a visible-light spectroscopic optical coherence tomography (vis-OCT) for in vivo retinal oximetry. To extract hemoglobin oxygen saturation (sO(2)) in individual retinal vessels, we established a comprehensive analytical model to describe optical absorption, optical scattering, and blood cell packing factor in the whole blood and fit the acquired vis-OCT signals from the bottom of each imaged vessel. We found that averaged sO(2) values in arterial and venous bloods were 95% and 72%, respectively.

Yi J; Wei Q; Liu W; Backman V; Zhang HF

2013-06-01

103

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

104

Imaging myocardial fiber orientation using polarization sensitive optical coherence tomography.  

UK PubMed Central (United Kingdom)

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 image the myocardial fiber orientation in a bovine heart muscle sample.

Fan C; Yao G

2013-03-01

105

Real-time in vivo computed optical interferometric tomography.  

UK PubMed Central (United Kingdom)

High-resolution real-time tomography of scattering tissues is important for many areas of medicine and biology(1-6). However, the compromise between transverse resolution and depth-of-field in addition to low sensitivity deep in tissue continue to impede progress towards cellular-level volumetric tomography. Computed imaging has the potential to solve these long-standing limitations. Interferometric synthetic aperture microscopy (ISAM)(7-9) is a computed imaging technique enabling high-resolution volumetric tomography with spatially invariant resolution. However, its potential for clinical diagnostics remains largely untapped since full volume reconstructions required lengthy postprocessing, and the phase-stability requirements have been difficult to satisfy in vivo. Here we demonstrate how 3-D Fourier-domain resampling, in combination with high-speed optical coherence tomography (OCT), can achieve high-resolution in vivo tomography. Enhanced depth sensitivity was achieved over a depth-of-field extended in real time by more than an order of magnitude. This work lays the foundation for high-speed volumetric cellular-level tomography.

Ahmad A; Shemonski ND; Adie SG; Kim HS; Hwu WM; Carney PS; Boppart SA

2013-06-01

106

Optical coherence tomography guided dental drill  

Energy Technology Data Exchange (ETDEWEB)

A dental drill that has one or multiple single mode fibers that can be used to image in the vicinity of the drill tip. It is valuable to image below the surface being drilled to minimize damage to vital or normal tissue. Identifying the boundary between decayed and normal enamel (or dentine) would reduce the removal of viable tissue, and identifying the nerve before getting too close with the drill could prevent nerve damage. By surrounding a drill with several optical fibers that can be used by an optical coherence domain reflectometry (OCDR) to image several millimeters ahead of the ablation surface will lead to a new and improved dental treatment device.

DaSilva, Luiz B. (Danville, CA); Colston, Jr., Bill W. (Livermore, CA); James, Dale L. (Tracy, CA)

2002-01-01

107

On the optical theory of photoelastic tomography.  

UK PubMed Central (United Kingdom)

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

Ainola L; Aben H

2004-06-01

108

Optical coherence photoacoustic microscopy: accomplishing optical coherence tomography and photoacoustic microscopy with a single light source  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We developed optical coherence photoacoustic microscopy (OC-PAM) to demonstrate that the functions of optical coherence tomography (OCT) and photoacoustic microscopy (PAM) can be achieved simultaneously by using a single illuminating light source. We used a pulsed broadband laser centered at 580 nm ...

Zhang, Xiangyang; Zhang, Hao F.; Jiao, Shuliang

109

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 unde...

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

110

Spectral-domain optical coherence tomography detects optic atrophy due to optic tract syndrome.  

UK PubMed Central (United Kingdom)

BACKGROUND: Unilateral injury of the optic tract leads to asymmetrical optic atrophy in both eyes derived from the crossing of the nerve fibers at the chiasm. This report demonstrates unique imaging appearances of optic atrophy due to this uncommon condition detected by spectral-domain optical coherence tomography (SD-OCT). METHODS: Cirrus and RTVue measurements were performed in four cases of optic tract syndrome. Circumpapillary retinal nerve fiber layer (cpRNFL) thickness was obtained from both instruments and ganglion cell complex (GCC) integrity was obtained from RTVue. The presumable reduction rates of quadrant cpRNFL thickness were calculated from the published normative database and compared between eyes with temporal hemianopia and those with nasal hemianopia. RESULTS: Both devices showed significant reduction of cpRNFL thickness, but did not have statistical difference in the reduction rates at temporal or nasal quadrant cpRNFL between contralateral and ipsilateral eyes to the lesion. Color-coded maps helped to visualize the unique pattern of cpRNFL and GCC thinning. CONCLUSIONS: SD-OCT can be used as a diagnostic tool for the optic tract syndrome.

Kanamori A; Nakamura M; Yamada Y; Negi A

2013-02-01

111

Positron emission tomography and optical tissue imaging  

Energy Technology Data Exchange (ETDEWEB)

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

112

Optical diffraction tomography for high resolution live cell imaging.  

UK PubMed Central (United Kingdom)

We report the experimental implementation of optical diffraction tomography for quantitative 3D mapping of refractive index in live biological cells. Using a heterodyne Mach-Zehnder interferometer, we record complex field images of light transmitted through a sample with varying directions of illumination. To quantitatively reconstruct the 3D map of complex refractive index in live cells, we apply optical diffraction tomography based on the Rytov approximation. In this way, the effect of diffraction is taken into account in the reconstruction process and diffraction-free high resolution 3D images are obtained throughout the entire sample volume. The quantitative refractive index map can potentially serve as an intrinsic assay to provide the molecular concentrations without the addition of exogenous agents and also to provide a method for studying the light scattering properties of single cells.

Sung Y; Choi W; Fang-Yen C; Badizadegan K; Dasari RR; Feld MS

2009-01-01

113

Optical diffraction tomography for high resolution live cell imaging.  

Science.gov (United States)

We report the experimental implementation of optical diffraction tomography for quantitative 3D mapping of refractive index in live biological cells. Using a heterodyne Mach-Zehnder interferometer, we record complex field images of light transmitted through a sample with varying directions of illumination. To quantitatively reconstruct the 3D map of complex refractive index in live cells, we apply optical diffraction tomography based on the Rytov approximation. In this way, the effect of diffraction is taken into account in the reconstruction process and diffraction-free high resolution 3D images are obtained throughout the entire sample volume. The quantitative refractive index map can potentially serve as an intrinsic assay to provide the molecular concentrations without the addition of exogenous agents and also to provide a method for studying the light scattering properties of single cells. PMID:19129896

Sung, Yongjin; Choi, Wonshik; Fang-Yen, Christopher; Badizadegan, Kamran; Dasari, Ramachandra R; Feld, Michael S

2009-01-01

114

Anatomical atlas-guided diffuse optical tomography of brain activation.  

Science.gov (United States)

We describe a neuroimaging 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 brain activation to the expected gyrus of the brain, in agreement with the results obtained with the subject-specific head anatomy. The benefits of this novel method derive from eliminating the need for subject-specific head anatomy and thus obviating the need for a subject-specific MRI to improve the anatomical interpretation of diffuse optical tomography images of brain activation. PMID:19643185

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

2009-07-28

115

Anatomical atlas-guided diffuse optical tomography of brain activation.  

UK PubMed Central (United Kingdom)

We describe a neuroimaging 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 brain activation to the expected gyrus of the brain, in agreement with the results obtained with the subject-specific head anatomy. The benefits of this novel method derive from eliminating the need for subject-specific head anatomy and thus obviating the need for a subject-specific MRI to improve the anatomical interpretation of diffuse optical tomography images of brain activation.

Custo A; Boas DA; Tsuzuki D; Dan I; Mesquita R; Fischl B; Grimson WE; Wells W 3rd

2010-01-01

116

Motion estimation for cardiac emission tomography by optical flow methods  

International Nuclear Information System (INIS)

This paper describes a new method for estimating the 3D, non-rigid object motion in a time sequence of images. The method is a generalization of a standard optical flow algorithm that is incorporated into a successive quadratic approximation framework. The method was evaluated for gated cardiac emission tomography using images obtained from a mathematical, 4D phantom and a physical, dynamic phantom. The results showed that the proposed method offers improved motion estimation accuracy relative to the standard optical flow method. Convergence of the proposed algorithm was evidenced with a monotonically decreasing objective function value with iteration. Practical application of the motion estimation method in cardiac emission tomography includes quantitative myocardial motion estimation and 4D, motion-compensated image reconstruction.

2008-06-07

117

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.

2002-01-01

118

Theory, developments and applications of optical coherence tomography  

Energy Technology Data Exchange (ETDEWEB)

In this paper, we review the developments in optical coherence tomography (OCT) for three-dimensional non-invasive imaging. A number of different OCT techniques are discussed in some detail including time-domain, frequency-domain, full-field, quantum and Doppler OCT. A theoretical treatment is given and some relevant comparisons made between various implementations. The current and potential applications of OCT are discussed, with close attention paid to biomedical imaging and its metrological issues.

Tomlins, P H [Photonics Group, National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW (United Kingdom); Wang, R K [Cranfield Biomedical Centre, Institute of Bioscience and Technology, Cranfield University at Silsoe, Bedfordshire MK45 4DT (United Kingdom)

2005-08-07

119

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; Scholz, Paula; Fauser, Sascha; Kirchhof, Bernd

2011-01-01

120

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

 
 
 
 
121

Fast image reconstruction in fluorescence optical tomography using data compression.  

UK PubMed Central (United Kingdom)

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.

Rudge TJ; Soloviev VY; Arridge SR

2010-03-01

122

X-ray luminescence optical tomography imaging: experimental studies.  

UK PubMed Central (United Kingdom)

We present a hybrid imaging modality, x-ray luminescence optical tomography (XLOT), in which collimated x-ray beams are used to excite phosphor-based contrast agents. Images are reconstructed from the optical signals, using the known x-ray beam location and spatial extent as priors. We demonstrate XLOT using phantom experiments with deep targets and show that the reconstructed signal varies by <12% when the depth changes from 4.2 to 7.7 mm. For simple source distributions, we find as few as two orthogonal projection measurements are sufficient for XLOT reconstruction.

Li C; Di K; Bec J; Cherry SR

2013-07-01

123

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

124

Quantitative fluorescence diffuse optical tomography in the presence of heterogeneities.  

UK PubMed Central (United Kingdom)

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

Correia T; Ducros N; D'Andrea C; Schweiger M; Arridge S

2013-06-01

125

Optical coherence tomography measurements and analysis methods in optical coherence tomography studies of diabetic macular edema.  

UK PubMed Central (United Kingdom)

OBJECTIVE: To evaluate optical coherence tomography (OCT) measurements and methods of analysis of OCT data in studies of diabetic macular edema (DME). DESIGN: Associations of pairs of OCT variables and results of 3 analysis methods using data from 2 studies of DME. PARTICIPANTS: Two hundred sixty-three subjects from a study of modified Early Treatment of Diabetic Retinopathy Study (mETDRS) versus modified macular grid (MMG) photocoagulation for DME and 96 subjects from a study of diurnal variation of DME. METHODS: Correlations were calculated for pairs of OCT variables at baseline and for changes in the variables over time. Distribution of OCT measurement changes, predictive factors for OCT measurement changes, and treatment group outcomes were compared when 3 measures of change in macular thickness were analyzed: absolute change in retinal thickness, relative change in retinal thickness, and relative change in retinal thickening. MAIN OUTCOME MEASURES: Concordance of results using different OCT variables and analysis methods. RESULTS: Center point thickness correlated highly with central subfield mean thickness (CSMT) at baseline (0.98-0.99). The distributions of changes in CSMT were approximately normally distributed for absolute change in retinal thickness and relative change in retinal thickness, but not for relative change in retinal thickening. Macular thinning in the mETDRS group was significantly greater than in the MMG group when absolute change in retinal thickness was used, but not when relative change in thickness and relative change in thickening were used. Relative change in macular thickening provides unstable data in eyes with mild degrees of baseline thickening, unlike the situation with absolute or relative change in retinal thickness. CONCLUSIONS: Central subfield mean thickness is the preferred OCT measurement for the central macula because of its higher reproducibility and correlation with other measurements of the central macula. Total macular volume may be preferred when the central macula is less important. Absolute change in retinal thickness is the preferred analysis method in studies involving eyes with mild macular thickening. Relative change in thickening may be preferable when retinal thickening is more severe.

Browning DJ; Glassman AR; Aiello LP; Bressler NM; Bressler SB; Danis RP; Davis MD; Ferris FL; Huang SS; Kaiser PK; Kollman C; Sadda S; Scott IU; Qin H

2008-08-01

126

Optic disk pit morphology and retinal detachment: optical coherence tomography with intraoperative correlation.  

UK PubMed Central (United Kingdom)

BACKGROUND: The pathogenesis of optic nerve head pits and associated retinal detachment, and the most effective surgical intervention when visual loss develops, remains unclear. METHODS: The morphology of the optic disk in patients with pits was investigated with optical coherence tomography. For those who underwent surgical treatment for pit-associated retinal detachment, the efficacy of treatment by vitrectomy and separation of the posterior hyaloid, with and without additional peeling of peripapillary tissue, was assessed. RESULTS: On optical coherence tomography imaging, 14 of 18 pits (78%) demonstrated a localized pit-like invagination, whereas 3 (17%) had disks with a generally excavated structure. For 16 of 18 pits (89%), there was evidence of condensed vitreous or glial tissue seen extending from the pit or inside the optic disk. Nine eyes with retinal detachment underwent vitrectomy, posterior hyaloid separation, and endolaser. The retinal detachment completely resolved in 6 of 6 cases where the surgeon additionally peeled the fibrous tissue from the pit and 2 of 3 cases where this was not performed. CONCLUSION: Spectral domain optical coherence tomography demonstrates the varying morphology of optic pit anatomy. Condensed vitreous strands or glial tissue in the optic nerve pit may also contribute to retinal detachment development.

Gregory-Roberts EM; Mateo C; Corcóstegui B; Schiff WM; Chang LK; Quiroz-Mercado H; Park S; Chang S

2013-02-01

127

Morphologic characteristics of optic nerve head drusen on spectral-domain optical coherence tomography.  

UK PubMed Central (United Kingdom)

PURPOSE: To evaluate the morphologic characteristics of optic nerve head drusen. DESIGN: Retrospective case series. METHODS: setting: Institutional (Seoul National University Bundang Hospital). patients: Sixty-one patients with optic nerve head drusen. observation procedure: Visible and buried optic nerve head drusen were identified using funduscopy, whereas homogenous and nonhomogenous optic nerve head drusen were identified using spectral-domain optical coherence tomography images. Buried optic nerve head drusen were classified according to the size. main outcome measures: Classification of optic nerve head drusen. RESULTS: Of 99 eyes in 61 patients, optic nerve head drusen were buried in 95 eyes and visible in 4 eyes. The patients with visible optic nerve head drusen were older on average than those with buried optic nerve head drusen (53.3 ± 8.6 years vs 13.5 ± 7.1 years; P < .001) and exhibited larger disc diameters (1643 ± 265 ?m vs 1287 ± 185 ?m; P = .016). All 4 eyes with visible optic nerve head drusen exhibited hyperreflective borders, which were not found in patients with buried optic nerve head drusen. Of 95 eyes with buried optic nerve head drusen, 64 eyes (67%) showed homogenous internal reflectivity, whereas 31 eyes (33%) showed nonhomogenous reflectivity with lobulations. Large optic nerve head drusen were associated with a small optic disc diameter, nonhomogenous internal reflectivity, a partial highly reflective border, intraretinal cysts, and increased temporal retinal nerve fiber layer thickness. CONCLUSIONS: Optic nerve head drusen have a diverse spectrum of spectral-domain optical coherence tomography findings associated with patient age and disc size.

Lee KM; Woo SJ; Hwang JM

2013-06-01

128

Liquid sorption investigation of porous media by optical coherence tomography  

Energy Technology Data Exchange (ETDEWEB)

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{sup -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.

Fabritius, Tapio; Myllylae, Risto [Measurement Techniques and Optoelectronics Laboratory, University of Oulu and Infotech Oulu, PO Box 4500, University of Oulu, 90014 Oulu (Finland)

2006-11-07

129

In vivo endoscopic multi-beam optical coherence tomography  

Energy Technology Data Exchange (ETDEWEB)

A multichannel optical coherence tomography (multi-beam OCT) system and an in vivo endoscopic imaging probe were developed using a swept-source OCT system. The distal optics were micro-machined to produce a high numerical aperture, multi-focus fibre optic array. This combination resulted in a transverse design resolution of <10 {mu}m full width half maximum (FWHM) throughout the entire imaging range, while also increasing the signal intensity within the focus of the individual channels. The system was used in a pre-clinical rabbit study to acquire in vivo structural images of the colon and ex vivo images of the oesophagus and trachea. A good correlation between the structural multi-beam OCT images and H and E histology was achieved, demonstrating the feasibility of this high-resolution system and its potential for in vivo human endoscopic imaging.

Standish, Beau A; Mariampillai, Adrian; Munce, Nigel R; Leung, Michael K K; Vitkin, I Alex [Deptartment of Medical Biophysics, University of Toronto, Toronto (Canada); Lee, Kenneth K C; Yang, Victor X D [Ontario Cancer Institute/University Health Network, Toronto (Canada)], E-mail: standish@ee.ryerson.ca

2010-02-07

130

Lens-free endoscopy probe for optical coherence tomography.  

UK PubMed Central (United Kingdom)

We present an ultrathin fiber-optic endoscopy probe for optical coherence tomography (OCT), which is made of a series of fused optical fibers instead of the conventional scheme based on an objective lens. The large-core fiber with a core diameter of 20 ?m was utilized for the probe, while a single-mode fiber of core diameter 8.2 ?m mainly delivered the OCT light. Those fibers were spliced with a bridge fiber of an intermediate core size. The guided light was stepwise converted to a beam of a large mode-field diameter to be radiated with a larger depth of focus. We obtained a 125 ?m thick all-fiber endoscopy probe with a side-viewing capability implemented by an angled fiber end. Successful OCT imaging was demonstrated with a swept-source OCT system and showed the practical applicability of our lens-free endoscopy probe.

Moon S; Piao Z; Kim CS; Chen Z

2013-06-01

131

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.

2006-11-07

132

In vivo optical coherence tomography: the role of the pathologist.  

UK PubMed Central (United Kingdom)

Optical coherence tomography (OCT) is a nondestructive, high-resolution imaging modality, providing cross-sectional, architectural images at near histologic resolutions, with penetration depths up to a few millimeters. Optical frequency domain imaging is a second-generation OCT technology that has equally high resolution with significantly increased image acquisition speeds and allows for large area, high-resolution tissue assessments. These features make OCT and optical frequency domain imaging ideal imaging techniques for surface and endoscopic imaging, specifically when tissue is unsafe to obtain and/or suffers from biopsy sampling error. This review focuses on the clinical impact of OCT in coronary, esophageal, and pulmonary imaging and the role of the pathologist in interpreting high-resolution OCT images as a complement to standard tissue pathology.

Hariri LP; Mino-Kenudson M; Mark EJ; Suter MJ

2012-12-01

133

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

134

Optical features for chronological aging and photoaging skin by optical coherence tomography.  

UK PubMed Central (United Kingdom)

The characteristics of skins in different aging processes were obtained by optical coherence tomography (OCT) single scattering model, and their optical parameters were analyzed quantitatively. Significant differences were found in epidermis thickness and attenuation coefficients in chronological aging skins and photonaging skins. These parameters can be served as indicators of skin type as well as the progress of aging. These results are valuable to the study of aging skin, and they could further help to understand the mechanism of aging.

Wu S; Li H; Zhang X; Li Z

2013-02-01

135

Detecting cell death with optical coherence tomography and envelope statistics  

Science.gov (United States)

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

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

2011-02-01

136

Detecting cell death with optical coherence tomography and envelope statistics.  

UK PubMed Central (United Kingdom)

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

Farhat G; Yang VX; Czarnota GJ; Kolios MC

2011-02-01

137

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 i...

Tycho, Andreas

138

Optical Coherence Tomography: An Emerging Technology for Biomedical Imaging and Optical Biopsy1  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Optical coherence tomography (OCT) is an emerging technology for performing high-resolution cross-sectional imaging. OCT is analogous to ultrasound imaging, except that it uses light instead of sound. OCT can provide cross-sectional images of tissue structure on the micron scale in situ and in real ...

Fujimoto, James G; Pitris, Costas; Boppart, Stephen A; Brezinski, Mark E

139

Artery phantoms for intravascular optical coherence tomography: diseased arteries.  

UK PubMed Central (United Kingdom)

ABSTRACT. We propose and test various strategies for the creation of artery phantoms mimicking different kinds of diseased arteries when imaged by intravascular optical coherence tomography (IVOCT). We first review the method for making healthy artery phantoms. We then describe the procedure to fabricate diseased artery phantoms with intima thickening, lipid pool, thin-capped fibroatheroma, calcification, and restenosis (homogeneous and layered) after stent apposition. For each case, a phantom is fabricated, an IVOCT image is obtained, and the image is compared to that of a real artery.

Bisaillon CÉ; Lamouche G

2013-09-01

140

Single fiber perfusion phantom for optical coherence tomography  

Science.gov (United States)

This paper presents the successful creation of new phantom for optical coherence tomography (OCT) aimed on perfusion simulation. The phantom is created from syringe pump and polypropylene hollow fiber with porous walls embeded in the glass capillary to provide small outer environment. Its function was tested by gold nanorods as a flowing medium and imaged by commercial swept-source OCT system. Results showed that the fiber is permeable for used gold nanorods which are frequently declared as possible contrast agents for OCT and this permeability can be displayed by OCT.

Podlipná, Petra; Kolá?, Radim

2013-06-01

 
 
 
 
141

Clinical diagnosis of oral submucous fibrosis with optical coherence tomography  

Science.gov (United States)

A swept-source optical coherence tomography (SS-OCT) system with a specially designed probe is built for clinical scanning of oral submucous fibrosis (OSF) patients. By analysing 44 OSF cases of SS-OCT scanning results, two indicators, including epithelium (EP) thickness and standard deviation (SD) of A-mode scan intensity in the laminar propria (LP) layer, are found useful for real-time OSF diagnosis. Statistics show that sensitivity and specificity of LP SD can reach 84.1 and 95.5 %, respectively. Also, both sensitivity and specificity of EP thickness can reach 100 %.

Lee, Cheng-Kuang; Tsai, Meng-Tsan; Yang, C. C.; Chiang, Chun-Pin

2009-11-01

142

[Optical coherence tomography in the imaging of the iridocorneal angle].  

UK PubMed Central (United Kingdom)

Anterior segment optical coherence tomography (AS OCT), enables visualization and measurements of the anterior segment of the eye. In particular, it is a valuable tool in the imaging of the iridocorneal angle. In this paper, we reviewed parameters used for analysis of the iridocorneal angle in AS OCT and compared changes of these parameters after cataract surgery, laser iridotomy and illumination. Special attention was paid to changes of such quantitative parameters as TISA (trabecular-iris space area), AOD (angle opening distance), and ARA (angle recess area).

Drzyzga ?; Mrukwa-Kominek E; Mielniczuk E; Romaniuk W

2011-01-01

143

Simultaneous angular multiplexing optical projection tomography at shifted focal planes.  

UK PubMed Central (United Kingdom)

We describe an angular multiplexing technique for optical projection tomography that improves resolution, signal-to-noise ratio, and imaging speed by ameliorating the trade-off between spatial resolution and depth of field and improving the light collection efficiency. Here we demonstrate that imaging at two orthogonal angular projections simultaneously, focused on shifted planes in the sample, improves the average spatial resolution by ~20% and the light collection efficiency by a factor of ~4, thereby enabling increased acquisition speed and reduced light dose.

Chen L; Andrews N; Kumar S; Frankel P; McGinty J; French PM

2013-03-01

144

Capturing the vital vascular fingerprint with optical coherence tomography.  

UK PubMed Central (United Kingdom)

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.

Liu G; Chen Z

2013-08-01

145

Combined two-photon microscopy and angiographic optical coherence tomography.  

UK PubMed Central (United Kingdom)

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

Kim B; Wang TJ; Li Q; Nam J; Hwang S; Chung E; Kim S; Kim KH

2013-08-01

146

Balanced detection for spectral domain optical coherence tomography.  

UK PubMed Central (United Kingdom)

The use and advantages of applying balanced-detection (BD) operation method to high speed spectral domain optical coherence tomography (SDOCT) are presented in this study, which we believe is the first such demonstration. Compared to conventional SDOCT, BD-SDOCT provides two unique advantages. First, the method can suppress background noise and autocorrelation artifacts in biological tissues. Second, it is a power-efficient method which is particularly helpful for high speed SDOCT to eliminate random intensity noise and to achieve shot noise limited detection. This performance allows in vivo three-dimensional tissue visualization with high imaging quality and high speed.

Kuo WC; Lai CM; Huang YS; Chang CY; Kuo YM

2013-08-01

147

Deterministic regularization of three-dimensional optical diffraction tomography.  

UK PubMed Central (United Kingdom)

In this paper, we discuss a deterministic regularization algorithm to handle the missing cone problem of three-dimensional optical diffraction tomography (ODT). The missing cone problem arises in most practical applications of ODT and is responsible for elongation of the reconstructed shape and underestimation of the value of the refractive index. By applying positivity and piecewise-smoothness constraints in an iterative reconstruction framework, we effectively suppress the missing cone artifact and recover sharp edges rounded out by the missing cone, and we significantly improve the accuracy of the predictions of the refractive index. We also show the noise-handling capability of our algorithm in the reconstruction process.

Sung Y; Dasari RR

2011-08-01

148

Deterministic regularization of three-dimensional optical diffraction tomography.  

Science.gov (United States)

In this paper, we discuss a deterministic regularization algorithm to handle the missing cone problem of three-dimensional optical diffraction tomography (ODT). The missing cone problem arises in most practical applications of ODT and is responsible for elongation of the reconstructed shape and underestimation of the value of the refractive index. By applying positivity and piecewise-smoothness constraints in an iterative reconstruction framework, we effectively suppress the missing cone artifact and recover sharp edges rounded out by the missing cone, and we significantly improve the accuracy of the predictions of the refractive index. We also show the noise-handling capability of our algorithm in the reconstruction process. PMID:21811316

Sung, Yongjin; Dasari, Ramachandra R

2011-08-01

149

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

Science.gov (United States)

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

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

2010-02-01

150

[Optical coherence tomography in diagnosis of intracranial hypertension in children].  

UK PubMed Central (United Kingdom)

UNLABELLED: Intracranial hypertension (IH) is important cause of optic disc edema. It is essential to distinguish the primary and secondary causes of IH. Persistent increasement of intracranial pressure over 200-250 mmH2O is caused by impairment of the balance between production and absorption of cerebrospinal fluid. Though the exact mechanism of IH is still unknown. PURPOSE: Assessment of usefulness of spectral optical coherence tomography with dual beam eye tracking (SLO/OCT) in diagnosis of intracranial hypertension in children. MATERIALS AND METHODS: 4 children (at the age of 3-12 years) with IH underwent an comprehensive ophthalmological examination, including visual acuity testing (Snellen charts), color vision (Ishihara charts), evaluation of anterior and posterior segment of the eye in slit lamp. On SLO/OCT (Spectralis, Heidelberg) scans RNFL profile of the optic disc was assessed at admission day and after 8 weeks of treatment with oral diuretics. In all patients MRI of the central nervous system was performed. RESULTS: In all children best corrected visual acuity and MRI scans were normal. 3 of 4 patients had secondary IH. Median global RNFL was 273 microm at admission day. In 3 of 4 children remission of optic disc edema was observed after 8 weeks of treatment with diuretics - median global RNFL was 138 microm. CONCLUSIONS: Diagnosis of intracranial hypertension requires interdisciplinary cooperation. SLO/OCT is useful in monitoring remission of the optic disc edema.

Mrugacz M; Szumi?ski M; Bakunowicz-?azarczyk A

2011-01-01

151

Optical coherence tomography image enhancement by using gold nanoparticles  

Science.gov (United States)

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

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

2011-08-01

152

Monte Carlo Simulations of Arterial Imaging with Optical Coherence Tomography  

Energy Technology Data Exchange (ETDEWEB)

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

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

2000-02-01

153

A versatile frequency domain multiplexer for optical coherence tomography  

Science.gov (United States)

In this paper we present a frequency multiplexed optical coherence tomography imaging method in which simultaneous data acquisition is enabled by a multiplexer. The multiplexer is based on a pair of Bragg cells, simultaneously driven at several frequencies that enable multiple paths in the reference arm. Multiple beams are created in the multiplexer and then recombined again so that the resulting beam multiplex can be inserted into a single mode fiber. In this paper we discuss the design principles for a multiplexer that supports the reflectivity measurements as well as polarization sensitive imaging at several different depths. We show how to design a system with a low footprint, while allowing broad optical bandwidth to be used for imaging in multiple channels with little crosstalk between adjacent channels.

Zurauskas, Mantas; Podoleanu, Adrian G.

2013-08-01

154

Transversal phase resolved polarization sensitive optical coherence tomography  

Energy Technology Data Exchange (ETDEWEB)

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

Pircher, Michael; Goetzinger, Erich; Leitgeb, Rainer; Hitzenberger, Christoph K [Department of Medical Physics, University of Vienna, Waehringerstr 13, A-1090 Vienna (Austria)

2004-04-07

155

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.

2006-01-01

156

Performance of latex balloons for optical computed tomography  

International Nuclear Information System (INIS)

[en] 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.

2013-06-26

157

Non-diffusing photochromic gel for optical computed tomography phantoms  

International Nuclear Information System (INIS)

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

2013-06-26

158

Multispot Monitoring for Use in Optical Coherence Tomography  

UK PubMed Central (United Kingdom)

Optical coherence tomography (herein "OCT") based analyte monitoring systems are disclosed. In one aspect, techniques are disclosed that can identify fluid flow in vivo (e.g., blood flow), which can act as a metric for gauging the extent of blood perfusion in tissue. For instance, if OCT is to be used to estimate the level of an analyte (e.g., glucose) in tissue, a measure of the extent of blood flow can potentially indicate the presence of an analyte correlating region, which would be suitable for analyte level estimation with OCT. Another aspect is related to systems and methods for scanning multiple regions. An optical beam is moved across the surface of the tissue in two distinct manners. The first can be a coarse scan, moving the beam to provide distinct scanning positions on the skin. The second can be a fine scan where the beam is applied for more detailed analysis.

SHAKESPEARE WALTER J; BENNETT WILLIAM HENRY; ICEMAN JASON T; APPLE HOWARD P; WALLACE PHILLIP WILLIAM; SCHURMAN MATTHEW J

159

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

160

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

2006-01-01

 
 
 
 
161

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

162

Integrated photoacoustic ophthalmoscopy and spectral-domain optical coherence tomography.  

UK PubMed Central (United Kingdom)

Both the clinical diagnosis and fundamental investigation of major ocular diseases greatly benefit from various non-invasive ophthalmic imaging technologies. Existing retinal imaging modalities, such as fundus photography, confocal scanning laser ophthalmoscopy (cSLO), and optical coherence tomography (OCT), have significant contributions in monitoring disease onsets and progressions, and developing new therapeutic strategies. However, they predominantly rely on the back-reflected photons from the retina. As a consequence, the optical absorption properties of the retina, which are usually strongly associated with retinal pathophysiology status, are inaccessible by the traditional imaging technologies. Photoacoustic ophthalmoscopy (PAOM) is an emerging retinal imaging modality that permits the detection of the optical absorption contrasts in the eye with a high sensitivity. In PAOM nanosecond laser pulses are delivered through the pupil and scanned across the posterior eye to induce photoacoustic (PA) signals, which are detected by an unfocused ultrasonic transducer attached to the eyelid. Because of the strong optical absorption of hemoglobin and melanin, PAOM is capable of non-invasively imaging the retinal and choroidal vasculatures, and the retinal pigment epithelium (RPE) melanin at high contrasts. More importantly, based on the well-developed spectroscopic photoacoustic imaging, PAOM has the potential to map the hemoglobin oxygen saturation in retinal vessels, which can be critical in studying the physiology and pathology of several blinding diseases such as diabetic retinopathy and neovascular age-related macular degeneration. Moreover, being the only existing optical-absorption-based ophthalmic imaging modality, PAOM can be integrated with well-established clinical ophthalmic imaging techniques to achieve more comprehensive anatomic and functional evaluations of the eye based on multiple optical contrasts. In this work, we integrate PAOM and spectral-domain OCT (SD-OCT) for simultaneously in vivo retinal imaging of rat, where both optical absorption and scattering properties of the retina are revealed. The system configuration, system alignment and imaging acquisition are presented.

Song W; Wei Q; Jiao S; Zhang HF

2013-01-01

163

Subluxed traumatic cataract: optical coherence tomography findings and clinical management  

Directory of Open Access Journals (Sweden)

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

Kuriyan AE; Flynn Jr HW; Yoo SH

2012-01-01

164

Self-spectral calibration for spectral domain optical coherence tomography  

Science.gov (United States)

A different real-time self-wavelength calibration method for spectral domain optical coherence tomography is presented in which interference spectra measured from two arbitrary points on the tissue surface are used for calibration. The method takes advantages of two favorable conditions of optical coherence tomography (OCT) signal. First, the signal back-scattered from the tissue surface is generally much stronger than that from positions in the tissue interior, so the spectral component of the surface interference could be extracted from the measured spectrum. Second, the tissue surface is not a plane and a phase difference exists between the light reflected from two different points on the surface. Compared with the zero-crossing automatic method, the introduced method has the advantage of removing the error due to dispersion mismatch or the common phase error. The method is tested experimentally to demonstrate the improved signal-to-noise ratio, higher axial resolution, and slower sensitivity degradation with depth when compared to the use of the zero-crossing method and applied to two-dimensional cross-sectional images of human finger skin.

Zhang, Xianling; Gao, Wanrong; Bian, Haiyi; Chen, Chaoliang; Liao, Jiuling

2013-06-01

165

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

2011-01-01

166

Endoscopic Bio-Imaging Using Optical Coherence Tomography  

Energy Technology Data Exchange (ETDEWEB)

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 {mu}m in air.

Ahn, Yeh Chan; Brenner, Matthew; Chen, Zhongping [Pukyong Nationanl University, Busan (Korea, Republic of)

2011-10-15

167

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.

2011-02-01

168

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

169

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

Science.gov (United States)

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

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

2013-09-09

170

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

UK PubMed Central (United Kingdom)

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

Kisimbi J; Shalchi Z; Mahroo OA; Mhina C; Sanyiwa AJ; Mabey D; Mohamed M; Plant GT

2013-09-01

171

Enhanced depth imaging optical coherence tomography of optic disc maculopathy without a visible optic pit.  

UK PubMed Central (United Kingdom)

A 57-year-old man presented with a three-month history of a small paracentral scotoma to the left of the fixation point in his left eye. He was previously healthy and used no medication. The best corrected visual acuity (with +1 dioptre sphere) was 1.0 (20/20) in the right eye and 0.9 (20/22) in the left eye, and the intraocular pressure was normal in both eyes. Except for some temporal peripapillary atrophy, the eyes were considered normal on biomicroscopy with no visible optic pits or colobomas and no posterior vitreous detachment. Enhanced depth imaging optical coherence tomography (OCT) (Spectralis HRA-OCT; Heidelberg Engineering, Heidelberg, Germany) of the left eye revealed a schisis-like separation of the outer retinal layers extending from the temporal disc margin to the nasal side of the fovea (Fig. 1). The OCT scan of the macular region in the right eye was normal. In both eyes, a small hyporeflective cavitation was observed adjacent and temporal to the stroma of the optic nerve head (Fig. 2 a,b). In the same region, en-face OCT (Copernicus HR SOCT; Optopol Technology SA, Zawiercie, Poland) showed sectors of hyporeflectivity in the outer retinal layers localised within the peripapillary rim area of both discs (Fig. 3 a,b). In the asymptomatic right eye, OCT disclosed a fine membrane extending from the temporal to the nasal edge of the disc (Fig. 2a). Fluorescein and indocyanine green angiography did not reveal any abnormal retinal or choroidal vessels. Late fluorescein staining (Optos 200Tx; Optos PLC, Dunfermline, Scotland, UK) was observed along the temporal border of the discs without any leakage into the macular area (Fig. 3 c,d).

Hedels C; Krohn J

2013-02-01

172

High resolution retinal imaging with a compact adaptive optics spectral domain optical coherence tomography system  

Science.gov (United States)

Adaptive optics (AO) is used to correct ocular aberrations primarily in the cornea, lens, and tear film of every eye. Among other applications, AO allows high lateral resolution images to be acquired with scanning laser ophthalmoscopy (SLO) and optical coherence tomography (OCT). Spectral domain optical coherence tomography (SDOCT) is a high-speed imaging technique that can acquire cross-sectional scans with micron-scale axial resolution at tens to hundreds of kHz line rates. We present a compact clinical AO-SDOCT system that achieves micron-scale axial and lateral resolution of retinal structures. The system includes a line scanning laser ophthalmscope (LSLO) for simultaneous wide-field retinal viewing and selection of regions-of-interest. OCT and LSLO imaging and AO correction performance are characterized. We present a case study of a single subject with hyper-reflective lesions associated with stable, resolved central serous retinopathy to compare and contrast AO as applied to scanning laser ophthalmoscopy and optical coherence tomography. The two imaging modes are found to be complementary in terms of information on structure morphology. Both provide additional information lacking in the other. This preliminary finding points to the power of combining SLO and SDOCT in a single research instrument for exploration of disease mechanisms, retinal cellular architecture, and visual psychophysics.

Hammer, Daniel X.; Iftimia, Nicusor V.; Bigelow, Chad E.; Ustun, Teoman E.; Bloom, Benjamin; Ferguson, R. Daniel; Burns, Stephen A.

2007-02-01

173

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

174

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

UK PubMed Central (United Kingdom)

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.

Zurauskas M; Rogers J; Podoleanu AG

2013-01-01

175

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

Energy Technology Data Exchange (ETDEWEB)

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.

Fabritius, Tapio; Myllylae, Risto [Measurement Techniques and Optoelectronics Laboratory, University of Oulu and Infotech Oulu, PO Box 4500, 90014 University of Oulu (Finland)

2006-06-21

176

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

2006-06-21

177

Optical diffraction tomography in an inhomogeneous background medium  

Science.gov (United States)

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

Devaney, A.; Cheng, J.

2008-08-01

178

Metrological reliability of optical coherence tomography in biomedical applications  

Science.gov (United States)

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.

Goloni, C. M.; Temporão, G. P.; Monteiro, E. C.

2013-09-01

179

Advanced scanning methods with tracking optical coherence tomography.  

UK PubMed Central (United Kingdom)

An upgraded optical coherence tomography system with integrated retinal tracker (TOCT) was developed. The upgraded system uses improved components to extend the tracking bandwidth, fully integrates the tracking hardware into the optical head of the clinical OCT system, and operates from a single software platform. The system was able to achieve transverse scan registration with sub-pixel accuracy (~10 microm). We demonstrate several advanced scan sequences with the TOCT, including composite scans averaged (co-added) from multiple B-scans taken consecutively and several hours apart, en face images collected by summing the A-scans of circular, line, and raster scans, and three-dimensional (3D) retinal maps of the fovea and optic disc. The new system achieves highly accurate OCT scan registration yielding composite images with significantly improved spatial resolution, increased signal-to-noise ratio, and reduced speckle while maintaining well-defined boundaries and sharp fine structure compared to single scans. Precise re-registration of multiple scans over separate imaging sessions demonstrates TOCT utility for longitudinal studies. En face images and 3D data cubes generated from these data reveal high fidelity image registration with tracking, despite scan durations of more than one minute.

Hammer D; Ferguson RD; Iftimia N; Ustun T; Wollstein G; Ishikawa H; Gabriele M; Dilworth W; Kagemann L; Schuman J

2005-10-01

180

Advanced scanning methods with tracking optical coherence tomography  

Science.gov (United States)

An upgraded optical coherence tomography system with integrated retinal tracker (TOCT) was developed. The upgraded system uses improved components to extend the tracking bandwidth, fully integrates the tracking hardware into the optical head of the clinical OCT system, and operates from a single software platform. The system was able to achieve transverse scan registration with sub-pixel accuracy (~10 ?m). We demonstrate several advanced scan sequences with the TOCT, including composite scans averaged (co-added) from multiple B-scans taken consecutively and several hours apart, en face images collected by summing the A-scans of circular, line, and raster scans, and three-dimensional (3D) retinal maps of the fovea and optic disc. The new system achieves highly accurate OCT scan registration yielding composite images with significantly improved spatial resolution, increased signal-to-noise ratio, and reduced speckle while maintaining well-defined boundaries and sharp fine structure compared to single scans. Precise re-registration of multiple scans over separate imaging sessions demonstrates TOCT utility for longitudinal studies. En face images and 3D data cubes generated from these data reveal high fidelity image registration with tracking, despite scan durations of more than one minute.

Hammer, Daniel X.; Ferguson, R. Daniel; Iftimia, Nicusor V.; Ustun, Teoman; Wollstein, Gadi; Ishikawa, Hiroshi; Gabriele, Michelle L.; Dilworth, William D.; Kagemann, Larry; Schuman, Joel S.

2005-10-01

 
 
 
 
181

Comparison of optic area measurement using fundus photography and optical coherence tomography between optic nerve head drusen and control subjects.  

UK PubMed Central (United Kingdom)

PURPOSE: To compare optic disc area measurement between optic nerve head drusen (ONHD) and control subjects using fundus photography, time-domain optical coherence tomography (TD-OCT) and spectral-domain optical coherence tomography (SD-OCT). We also made a comparison between each of the three techniques. METHODS: We performed our study on 66 eyes (66 patients) with ONHD and 70 healthy control subjects (70 controls) with colour ocular fundus photography at 20º (Zeiss FF 450 IR plus), TD-OCT (Stratus OCT) with the Fast Optic Disc protocol and SD-OCT (Cirrus OCT) with the Optic Disc Cube 200 × 200 protocol for measurement of the optic disc area. The measurements were made by two observers and in each measurement a correction of the image magnification factor was performed. Measurement comparison using the Student's t-test/Mann-Whitney U test, the intraclass correlation coefficient, Pearson/Spearman rank correlation coefficient and the Bland-Altman plot was performed in the statistical analysis. RESULTS: Mean and standard deviation (SD) of the optic disc area in ONHD and in controls was 2.38 (0.54) mm(2) and 2.54 (0.42) mm(2), respectively with fundus photography; 2.01 (0.56) mm(2) and 1.66 (0.37) mm(2), respectively with TD-OCT, and 2.03 (0.49) mm(2) and 1.75 (0.38) mm(2), respectively with SD-OCT. In ONHD and controls, repeatability of optic disc area measurement was excellent with fundus photography and optical coherence tomography (TD-OCT and SD-OCT), but with a low degree of agreement between both techniques. CONCLUSIONS: Optic disc area measurement is smaller in ONHD compared to healthy subjects with fundus photography, unlike time-domain and spectral-domain optical coherence tomography in which the reverse is true. Both techniques offer good repeatability, but a low degree of correlation and agreement, which means that optic disc area measurement is not interchangeable or comparable between techniques.

Flores-Rodríguez P; Gili P; Martín-Ríos MD; Grifol-Clar E

2013-03-01

182

[Corneal flap analysis after LASIK and femto-LASIK using optical coherence tomography and optical sections].  

UK PubMed Central (United Kingdom)

Two groups of patients were enrolled into the study, each group included 15 patients (30 eyes). Evolution 3E mechanical microkeratome ("Moria") was used to create LASIK flaps in the 1st group. VISUMAX laser microkeratome ("Carl Zeiss Meditec") was used in the 2nd group. Optical coherence tomography showed irregularity of flap thickness in the 1st group. In the 2nd group flap thickness was regular. According to Pentacam data the posterior corneal surface had no postoperative changes in both groups.

Kostin OA; Rebrikov SV; Ovchinnikov AI; Stepanov AA

2012-09-01

183

Characteristic Findings of Optical Coherence Tomography in Retinal Angiomatous Proliferation  

Science.gov (United States)

Purpose To identify the unique pathologic findings of retinal angiomatous proliferation (RAP) in optical coherence tomography (OCT). Methods Retrospectively, 29 eyes of 25 patients with age-related macular degeneration and complicated RAP were analyzed. All 29 eyes had choroidal neovascularization (CNV) in the area of pigment epithelial detachment (PED) or adjacent to it, which was visible with fluorescein angiography or indocyanine green angiography. Cross-sectional images were obtained by OCT scanning through the CNV lesions. Results Six distinctive findings of OCT included drusen (100%), inner retinal cyst (80%), outer retinal cyst (68%), fibrovascular PED (84%), serous retinal detachment (40%), and PED (68%). Conclusions Through analysis of OCT findings, we revealed six different types of lesions distinctive of RAP which may provide helpful diagnostic information for subsequent treatment and predicting the prognosis of RAP.

Lim, Eun-Hae; Kim, Chul Gu; Cho, Sung Won; Lee, Tae Gon

2013-01-01

184

Optical Coherence Tomography and Raman Spectroscopy of the retina  

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-01-16

185

Foveal duplication artifact with spectral-domain optical coherence tomography.  

UK PubMed Central (United Kingdom)

The authors describe a rare artifact on two different spectral-domain optical coherence tomography (OCT) systems and explain its origin in patient- rather than hardware-related errors. During evaluation on spectral-domain OCT, four patients registered twin foveal depressions on the retinal thickness map display and were initially unable to fixate on the given target. Repeat scans on the same OCT system without changing scan protocol demonstrated no artifact after the patients began to fixate well, except in one patient who had nystagmus. Fundus and autofluorescence evaluation revealed no true duplication of fovea. Performing a repeat scan with greater focus on patient compliance is necessary when such artifactual anomalies are encountered.

Kalliath J; Shukla D

2013-01-01

186

Enhanced Depth Imaging Optical Coherence Tomography Findings in Behcet Disease.  

UK PubMed Central (United Kingdom)

Abstract Purpose: Investigation of subfoveal choroidal thickness in Behçet disease (BD) with enhanced depth imaging optical coherence tomography (EDI-OCT). Methods: The study included 35 patients with posterior uveitis (PU) associated with BD, 35 patients with BD without ocular involvement, and 30 healthy controls. Results: There were no significant differences between the groups in terms of age, gender, axial length, or spherical equivalent refractive error. The mean subfoveal choroidal thickness was thinner in eyes with PU than in eyes without PU and healthy controls (p?=?0.026). Conclusion: EDI-OCT is a beneficial test for evaluating choroid morphology in BD. Thinning of the subfoveal choroidal tissue has been observed in patients with BD-associated PU.

Coskun E; Gurler B; Pehlivan Y; Kisacik B; Okumus S; Yayuspay? R; Ozcan E; Onat AM

2013-07-01

187

Characteristic Findings of Optical Coherence Tomography in Retinal Angiomatous Proliferation.  

UK PubMed Central (United Kingdom)

PURPOSE: To identify the unique pathologic findings of retinal angiomatous proliferation (RAP) in optical coherence tomography (OCT). METHODS: Retrospectively, 29 eyes of 25 patients with age-related macular degeneration and complicated RAP were analyzed. All 29 eyes had choroidal neovascularization (CNV) in the area of pigment epithelial detachment (PED) or adjacent to it, which was visible with fluorescein angiography or indocyanine green angiography. Cross-sectional images were obtained by OCT scanning through the CNV lesions. RESULTS: Six distinctive findings of OCT included drusen (100%), inner retinal cyst (80%), outer retinal cyst (68%), fibrovascular PED (84%), serous retinal detachment (40%), and PED (68%). CONCLUSIONS: Through analysis of OCT findings, we revealed six different types of lesions distinctive of RAP which may provide helpful diagnostic information for subsequent treatment and predicting the prognosis of RAP.

Lim EH; Han JI; Kim CG; Cho SW; Lee TG

2013-10-01

188

Combined two-photon microscopy and angiographic optical coherence tomography.  

Science.gov (United States)

ABSTRACT. A combined two-photon microscopy (TPM) and angiographic optical coherence tomography (OCT) is developed, which can provide molecular, cellular, structural, and vascular information of tissue specimens in vivo. This combined system is implemented by adding an OCT vasculature visualization method to the previous combined TPM and OCT, and then is applied to in vivo tissue imaging. Two animal models, a mouse brain cranial window model and a mouse ear cancer model, are used. Both molecular, cellular information at local regions of tissues, and structural, vascular information at relatively larger regions are visualized in the same sections. In vivo tissue microenvironments are better elucidated by the combined TPM and angiographic OCT. PMID:23922122

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

2013-08-01

189

In Vivo Human Retinal Imaging by Optical Coherence Tomography  

Directory of Open Access Journals (Sweden)

Full Text Available In the last decade retinal diseases have become prevalently in India and it is growing alarmingly. Fortunately, most of blindness are caused are preventable if treated at appropriate time. Early detection of such retinal diseases like diabetic retinopathy, macular degeneration, retinal detachment and glaucoma is very vital. Optical coherence tomography (OCT) is an In vivo imaging technique for cross sectional imaging of the retinal layers. An Image segmentation algorithm to analyze the thickness of the cross sectional of the retinal layers has been used. The changes in the thickness of the retinal layers in microns scale (10-20 microns) will have a significant impact in the vision if not detected and diagnosed early. The measurement of quantitative thickness of the retinal layer non-invasively using this objective method may facilitate the ophthalmologist to prescribe the diagnosis at the appropriate time that would more likely save the vision of the patient.

R. Revathi; P. Rajkumar

2013-01-01

190

Diffuse optical tomography in the presence of a chest wall.  

UK PubMed Central (United Kingdom)

Diffuse optical tomography (DOT) has been employed to derive spatial maps of physiologically important chromophores in the human breast, but the fidelity of these images is often compromised by boundary effects such as those due to the chest wall. We explore the image quality in fast, data-intensive analytic and algebraic linear DOT reconstructions of phantoms with subcentimeter target features and large absorptive regions mimicking the chest wall. Experiments demonstrate that the chest wall phantom can introduce severe image artifacts. We then show how these artifacts can be mitigated by exclusion of data affected by the chest wall. We also introduce and demonstrate a linear algebraic reconstruction method well suited for very large data sets in the presence of a chest wall.

Ban HY; Busch DR; Pathak S; Moscatelli FA; Machida M; Schotland JC; Markel VA; Yodh AG

2013-02-01

191

Imaging of mouse embryonic eye development using optical coherence tomography  

Science.gov (United States)

Congenital abnormalities are often caused by genetic disorders which alter the normal development of the eye. Embryonic eye imaging in mouse model is important for understanding of normal and abnormal eye development and can contribute to prevention and treatment of eye defects in humans. In this study, we used Swept Source Optical Coherence Tomography (SS-OCT) to image eye structure in mouse embryos at 12.5 to 17.5 days post coitus (dpc). The imaging depth of the OCT allowed us to visualize the whole eye globe at these stages. Different ocular tissues including lens, cornea, eyelids, and hyaloid vasculature were visualized. These results suggest that OCT imaging is a useful tool to study embryonic eye development in the mouse model.

Syed, Saba H.; Kasiraj, Alyssa; Larina, Irina V.; Dickinson, Mary E.; Larin, Kirill V.

2010-02-01

192

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.

2010-06-01

193

4D embryonic cardiography using gated optical coherence tomography.  

Science.gov (United States)

Simultaneous imaging of very early embryonic heart structure and function has technical limitations of spatial and temporal resolution. We have developed a gated technique using optical coherence tomography (OCT) that can rapidly image beating embryonic hearts in four-dimensions (4D), at high spatial resolution (10-15 mum), and with a depth penetration of 1.5 - 2.0 mm that is suitable for the study of early embryonic hearts. We acquired data from paced, excised, embryonic chicken and mouse hearts using gated sampling and employed image processing techniques to visualize the hearts in 4D and measure physiologic parameters such as cardiac volume, ejection fraction, and wall thickness. This technique is being developed to longitudinally investigate the physiology of intact embryonic hearts and events that lead to congenital heart defects. PMID:19503392

Jenkins, M W; Rothenberg, F; Roy, D; Nikolski, V P; Hu, Z; Watanabe, M; Wilson, D L; Efimov, I R; Rollins, A M

2006-01-23

194

4D embryonic cardiography using gated optical coherence tomography.  

UK PubMed Central (United Kingdom)

Simultaneous imaging of very early embryonic heart structure and function has technical limitations of spatial and temporal resolution. We have developed a gated technique using optical coherence tomography (OCT) that can rapidly image beating embryonic hearts in four-dimensions (4D), at high spatial resolution (10-15 mum), and with a depth penetration of 1.5 - 2.0 mm that is suitable for the study of early embryonic hearts. We acquired data from paced, excised, embryonic chicken and mouse hearts using gated sampling and employed image processing techniques to visualize the hearts in 4D and measure physiologic parameters such as cardiac volume, ejection fraction, and wall thickness. This technique is being developed to longitudinally investigate the physiology of intact embryonic hearts and events that lead to congenital heart defects.

Jenkins MW; Rothenberg F; Roy D; Nikolski VP; Hu Z; Watanabe M; Wilson DL; Efimov IR; Rollins AM

2006-01-01

195

Fourier domain optical coherence tomography for high-precision profilometry  

Science.gov (United States)

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

Lawman, Samuel; Liang, Haida

2009-07-01

196

Dynamic diffuse optical tomography imaging of peripheral arterial disease.  

UK PubMed Central (United Kingdom)

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

Khalil MA; Kim HK; Kim IK; Flexman M; Dayal R; Shrikhande G; Hielscher AH

2012-09-01

197

Numerical study of grating-assisted optical diffraction tomography  

International Nuclear Information System (INIS)

We study the resolution of an optical diffraction tomography system in which the objects are either in an homogeneous background or deposited onto a glass prism, a prism surmounted by a thin metallic film or a prism surmounted by a metallic film covered by a periodically nanostructured dielectric layer. For all these configurations, we present an inversion procedure that yields the map of the relative permittivity of the objects from their diffracted far field. When multiple scattering can be neglected, we show that the homogeneous, prism, and metallic film configurations yield a resolution about ?/4 while the grating substrate yields a resolution better than ?/10. When Born approximation fails, we point out that it is possible to neglect the coupling between the object and the substrate and account solely for the multiple scattering within the objects to obtain a satisfactory reconstruction. Last, we present the robustness of our inversion procedure to noise

2007-01-01

198

Optical coherence tomography for vulnerability assessment of sandstone.  

UK PubMed Central (United Kingdom)

Sandstone is an important cultural heritage material, in both architectural and natural settings, such as neolithic rock art panels. The majority of deterioration effects in porous materials such as sandstone are influenced by the presence and movement of water through the material. The presence of water within the porous network of a material results in changes in the optical coherence tomography signal intensity that can be used to monitor the wetting front of water penetration of dry porous materials at various depths. The technique is able to detect wetting front velocities from 1 cm s(-1) to 10(-6) cm s(-1), covering the full range of hydraulic conductivities likely to occur in natural sandstones from pervious to impervious.

Bemand E; Liang H

2013-05-01

199

Construction of the Optical Delay Line for the Optical Coherence Tomography  

Directory of Open Access Journals (Sweden)

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; I-Jen Hsu

2013-01-01

200

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.

2012-01-01

 
 
 
 
201

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

International Nuclear Information System (INIS)

Optical coherence tomography (OCT) is a promising new technique for characterizing the structural changes of articular cartilage in osteoarthritis (OA). The calculation of quantitative parameters from the OCT signal is an important step to develop OCT as an effective diagnostic technique. In this study, two novel parameters for the quantification of optical surface reflection and surface roughness from OCT measurements are introduced: optical surface reflection coefficient (ORC), describing the amount of a ratio of the optical reflection from cartilage surface with respect to that from a reference material, and OCT roughness index (ORI) indicating the smoothness of the cartilage surface. The sensitivity of ORC and ORI to detect changes in bovine articular cartilage samples after enzymatic degradations of collagen and proteoglycans using collagenase and trypsin enzymes, respectively, was tested in vitro. A significant decrease (p

2009-11-21

202

Optical coherence tomography classification of diabetic cystoid macular edema  

Directory of Open Access Journals (Sweden)

Full Text Available 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 mellitus of duration from 5 to 20 years. All patients were diagnosed to have CME, as assessed by OCT, with measurement of the vertical size of the largest macular cyst and maximum macular thickness, and the relation between them.Results: Patients were divided into four groups. Eyes with cysts less than 30% of macular thickness were considered to have CME I (n = 4, 3.84%), while those between 30% and 60% were considered to have CME II (n = 62, 59.62%). Eyes with cysts between 60% and 90% of macular thickness were considered to have CME III (n = 36, 34.62%). CME IV was diagnosed when the size of the cyst became more than 90% of the macular thickness, and this was encountered in two eyes (1.92%).Conclusions: OCT is a useful technique for quantitative measurement and helps in better anatomical characterization of CME, and this classification of diabetic CME may be of value in classification of CME due to causes other than diabetes.Keywords: optical coherence tomography, cystoid macular edema, diabetic retinopathy

Helmy YM; Atta Allah HR

2013-01-01

203

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

2007-01-01

204

[Analysis of optical coherence tomography in early stage of optic neuritis in multiple sclerosis patients].  

UK PubMed Central (United Kingdom)

OBJECTIVE: To detect the changes in the retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC) in the eyes of multiple sclerosis patients during the early stage of optic neuritis. METHODS: A prospective case series study. Suspected acute optic neuritis of multiple sclerosis (MS) patients who attended the department of ophthalmology in Peking Union Medical College hospital from Feb. 2007 to Nov. 2010 were collected. Twenty two MS patients were evaluated within the first week of the attack of acute optic neuritis. The average thickness of RNFL and GCC was measured and a three dimensional image of optic disk was reconstructed using optical coherence tomography (OCT). RESULTS: Within the first week of onset, the average thickness of RNFL and GCC of first attack eyes increased 75% and 64%, respectively. The average thickness of RNFL and GCC in relapsed eyes decreased 91.7% and 62.5% respectively. The average thickness of RNFL and GCC of the fellow eyes also increased 60% and 43% respectively, within the first week of onset. More cases of optic disk edema and thickening of RNFL were found by OCT than by direct ophthalmoscopy. CONCLUSIONS: Different changes of the thickness of RNFL and GCC and morphology of the optic disk were detected during the early stage of the initial attack or relapsed optic neuritis in MS patients. OCT could detect such differences.

Cheng GW; Zhao JL; Liang Z; Zhong Y; Zhang H; Ma JM; Sui RF; Mao J

2011-10-01

205

Correlation between spectral-domain optical coherence tomography and autofluorescence findings in sclerochoroidal calcification.  

UK PubMed Central (United Kingdom)

OBJECTIVE: The purpose of this article is to report the correlation between spectral domain-optical coherence tomography and autofluorescence findings in 3 consecutive cases with sclerochoroidal calcification. DESIGN: Observational case series. PARTICIPANTS: The study involved 3 patients with bilateral sclerochoroidal calcification. METHODS: B-scan ultrasonography, spectral domain-optical coherence tomography, and autofluorescence were performed in each eye. The choroidal vascular thickness and autofluorescence patterns of the calcified plaques were evaluated with spectral domain-optical coherence tomography and autofluorescence, respectively. RESULTS: An important variation of choroidal vascular thickness overlying sclerochoroidal calcification was observed in spectral domain-optical coherence tomography. Autofluorescence showed 2 patterns of autofluorescence closely correlated with changes in choroidal vascular thickness. In those zones where the thicknesses of choriocapillaris complex were reduced, a hyperautofluorescence pattern was observed in autofluorescence. The hypoautofluorescence pattern was observed in outpouching zone of retinal pigment epithelium-choriocapillaris complex seen in spectral domain-optical coherence tomography. The hypoautofluorescence pattern was closely correlated with remarkable reduction of the choriocapillaris complex. There were no significant differences between the patterns of autofluorescence except the extension. CONCLUSIONS: Spectral domain-optical coherence tomography and autofluorescence are noninvasive complementary imaging studies that may help to improve our knowledge about sclerochoroidal calcification. Characteristic patterns of autofluorescence were closely correlated with spectral domain-optical coherence tomography findings. More patients need to be evaluated with both complementary studies to establish conclusions related with these findings.

Caminal-Mitjana JM; Padrón-Pérez N; Arias-Barquet L; Rubio-Caso MJ; Català-Mora J

2013-08-01

206

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

International Nuclear Information System (INIS)

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

2006-04-21

207

Pathophysiology of acute coronary syndrome assessed by optical coherence tomography.  

UK PubMed Central (United Kingdom)

Optical coherence tomography (OCT) is an optical analogue of intravascular ultrasound (IVUS), which provides high-resolution images of the coronary arteries up to 10microm. OCT allows us to demonstrate clearly culprit lesion morphologies in detail including types of plaque, plaque disruption, thrombus, fibrous cap thickness, and the frequency of thin-capped fibroatheroma (TCFA) in acute coronary syndrome (ACS), as described in previous histological examinations. Furthermore, clinical silent disrupted plaques and non-ruptured TCFAs, which are thought to be precursors of ACS and vulnerable plaques, have also been demonstrated by OCT not only in culprit but also in non-culprit vessels in ACS. OCT also identified the mechanisms of late thrombosis after bare-metal stent and drug-eluting stent implantation. Development of the next-generation frequency-domain OCT system and prospective studies in a large population may allow us to realize the pathophysiology of ACS in detail in vivo in humans, and these may provide us new insights into the etiology and treatment of coronary artery disease in the near future for predicting and preventing ACS.

Akasaka T; Kubo T; Mizukoshi M; Tanaka A; Kitabata H; Tanimoto T; Imanishi T

2010-07-01

208

Pathophysiology of acute coronary syndrome assessed by optical coherence tomography.  

Science.gov (United States)

Optical coherence tomography (OCT) is an optical analogue of intravascular ultrasound (IVUS), which provides high-resolution images of the coronary arteries up to 10microm. OCT allows us to demonstrate clearly culprit lesion morphologies in detail including types of plaque, plaque disruption, thrombus, fibrous cap thickness, and the frequency of thin-capped fibroatheroma (TCFA) in acute coronary syndrome (ACS), as described in previous histological examinations. Furthermore, clinical silent disrupted plaques and non-ruptured TCFAs, which are thought to be precursors of ACS and vulnerable plaques, have also been demonstrated by OCT not only in culprit but also in non-culprit vessels in ACS. OCT also identified the mechanisms of late thrombosis after bare-metal stent and drug-eluting stent implantation. Development of the next-generation frequency-domain OCT system and prospective studies in a large population may allow us to realize the pathophysiology of ACS in detail in vivo in humans, and these may provide us new insights into the etiology and treatment of coronary artery disease in the near future for predicting and preventing ACS. PMID:20554431

Akasaka, Takashi; Kubo, Takashi; Mizukoshi, Masato; Tanaka, Atsushi; Kitabata, Hironori; Tanimoto, Takashi; Imanishi, Toshio

2010-06-15

209

Advanced integrated spectrometer designs for miniaturized optical coherence tomography systems  

Science.gov (United States)

Optical coherence tomography (OCT) has enabled clinical applications that revolutionized in vivo medical diagnostics. Nevertheless, its current limitations owing to cost, size, complexity, and the need for accurate alignment must be overcome by radically novel approaches. Exploiting integrated optics, the central components of a spectral-domain OCT (SD-OCT) system can be integrated on a chip. Arrayed-waveguide grating (AWG) spectrometers with their high spectral resolution and compactness are excellent candidates for on-chip SD-OCT systems. However, specific design-related issues of AWG spectrometers limit the performance of on-chip SD-OCT systems. Here we present advanced AWG designs which could overcome the limitations arising from free spectral range, polarization dependency, and curved focal plane of the AWG spectrometers. Using these advanced AWG designs in an SD-OCT system can provide not only better overall performance but also some unique aspects that a commercial system does not have. Additionally, a partially integrated OCT system comprising an AWG spectrometer and an integrated beam splitter, as well as the in vivo imaging using this system are demonstrated.

Akca, B. I.; Považay, B.; Chang, L.; Alex, A.; Wörhoff, K.; de Ridder, R. M.; Drexler, W.; Pollnau, M.

2013-06-01

210

Monte Carlo modeling of human tooth optical coherence tomography imaging  

Science.gov (United States)

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.

Shi, Boya; Meng, Zhuo; Wang, Longzhi; Liu, Tiegen

2013-07-01

211

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

212

Optical coherence tomography: imaging architect for dermal microdialysis in psoriasis  

Science.gov (United States)

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

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

2011-02-01

213

Optical coherence tomography: Imaging of the choroid and beyond.  

Science.gov (United States)

Seventy percent of the blood flow to the eye goes to the choroid, a structure that is vitally important to the function of the retina. The in vivo structure of the choroid in health and disease is incompletely visualized with traditional imaging modalities, including indocyanine green angiography, ultrasonography, and spectral domain optical coherence tomography (OCT). Use of new OCT modalities, including enhanced depth imaging OCT, image averaging, and swept-source OCT, have led to increased visualization of the choroidal anatomy. The correlation of these new anatomical findings with other imaging modalities results increases understanding of many eye diseases and recognises of new ones. The status of the choroid appears to be a crucial determinant in the pathogenesis of diseases such as age-related choroidal atrophy, myopic chorioretinal atrophy, central serous chorioretinopathy, chorioretinal inflammatory diseases, and tumors. Extension of these imaging techniques has provided insights into abnormalities of the sclera and optic nerve. Future developments will include blood flow information, 3D rendering of various ocular structures, and the ability to evaluate changes in 3D structural information over time (4D imaging). PMID:23916620

Mrejen, Sarah; Spaide, Richard F

2013-08-02

214

Applications of optical coherence tomography in cataract surgery.  

UK PubMed Central (United Kingdom)

PURPOSE OF REVIEW: The rapid emergence and widespread adoption of optical coherence tomography (OCT) has spurred the development of many ophthalmic applications. Spectral domain OCT provides high-resolution in-vivo images of both anterior and posterior segments of the eye. Innovations in anterior segment OCT (AS-OCT) aim to improve refractive accuracy and reduce surgical risks. This review focuses on the utility of AS-OCT in cataract surgery for preoperative assessment, intraoperative assistance, and postoperative management to improve surgical outcomes. RECENT FINDINGS: Recent advances in AS-OCT for preoperative planning include characterization of dry eye and ocular surface conditions, calculation of intraocular lens (IOL) power, delineation of anterior chamber structures, and assessment of risk factors for postoperative complications. Successful intraoperative use of AS-OCT has been described for in-vivo assessment of clear cornea wound architecture and OCT-guided femtosecond laser-assisted cataract surgery. The essential roles of OCT in managing postoperative complications include characterization of maculopathy or corneal wound integrity, assessment of IOL stability or optical changes, and evaluation of laser-assisted in situ keratomileusis flaps after cataract surgery. SUMMARY: In its rapidly evolving state, the utility of OCT in cataract surgery continues to broaden with applications from preoperative planning, intraoperative image-based treatments, and postoperative care. We advocate the judicious use of OCT, wherever clinically indicated, because routine use may not be clinically necessary or economically feasible for each stage of cataract evaluation and management.

Nguyen P; Chopra V

2013-01-01

215

Noninvasive evaluation of retinal leakage using optical coherence tomography.  

UK PubMed Central (United Kingdom)

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 changes along the light path within the human ocular fundus. RESULTS: A total of 140 comparisons were made, 77 between areas of regions receiving the same classification (intact or disrupted BRB) and 63 between areas of regions receiving distinct classifications, from 4 pathological cases: 2 eyes with nonproliferative diabetic retinopathy and 2 eyes with wet age-related macular degeneration. In all cases, the distribution of OCT data between regions of intact and regions of disrupted BRB, identified by the retinal leakage analyzer, was quantified and was statistically significantly different (p < 0.001). In addition, it was found that the differences could be localized in the retina to specific structural sequences. CONCLUSIONS: Using a novel method to analyze OCT data, we showed that it may be possible to quantify differences in the extracellular compartment in eyes with retinal disease and alterations of the BRB. Based on quantitative techniques, our findings demonstrate the presence of indirect information on the BRB status within noninvasive OCT data.

Bernardes R; Santos T; Serranho P; Lobo C; Cunha-Vaz J

2011-01-01

216

Visualization of vitreomacular tractions with en face optical coherence tomography.  

UK PubMed Central (United Kingdom)

BACKGROUND: In vitreomacular traction syndrome, an incomplete vitreous detachment with persistent vitreous traction on the macula is present. This condition may determine formation of epiretinal membranes, macular puckering, macular oedema, and traction macular detachment. Recently introduced en face optical coherence tomography (OCT) provides not only longitudinal B-scan but also coronal C-scan images of the retina. METHODS: Fifteen eyes of 11 non-diabetic patients presenting vitreomacular traction syndrome have been evaluated with en face OCT (OTI, Toronto, Ontario, Canada). RESULTS: In 12 eyes, cystoid macular oedema was detectable at fundus examination and was associated with a broad-based adherence of the posterior hyaloid to the macula. In three eyes, foveal detachment appeared to be associated with focal foveal vitreoretinal traction. In all eyes, the lateral extent of the hyaloidal tractions on the macula was clearly detectable at coronal C-scan. They appeared as sigmoid hyper-reflective bands in the hyporeflective vitreous chamber. Overlay of C-scans on red-free confocal images allowed the visualization of the edges of the adherences in relation to the structures of the posterior pole. CONCLUSIONS: The C-scan images allowed clear visualization of the total extension of the posterior vitreomacular adherences and their relationships with the vascular arcades, the optic disc, and the fovea.

Forte R; Pascotto F; de Crecchio G

2007-11-01

217

Application of optical coherence tomography to automated contact lens metrology.  

UK PubMed Central (United Kingdom)

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

Davidson BR; Barton JK

2010-01-01

218

Application of optical coherence tomography to automated contact lens metrology  

Science.gov (United States)

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

Davidson, Bryan R.; Barton, Jennifer K.

2010-01-01

219

Retina-simulating phantom for optical coherence tomography.  

UK PubMed Central (United Kingdom)

ABSTRACT. 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.

Baxi J; Calhoun W; Sepah YJ; Hammer DX; Ilev I; Joshua Pfefer T; Nguyen QD; Agrawal A

2014-02-01

220

Optic neuritis interferes with optical coherence tomography and magnetic resonance imaging correlations.  

UK PubMed Central (United Kingdom)

BACKGROUND: Retinal nerve fibre layer (RNFL) thinning is associated with brain atrophy in multiple sclerosis (MS). An influence of optic neuritis is well documented but sparsely investigated. Recently, the retinal ganglion cell layer (GCL) has been shown to provide superior information regarding visual function and retinal neurodegeneration as compared with RNFL. OBJECTIVE: To investigate the association of white and grey matter brain volume with peripapillary RNFL and macular GCL in MS patients with and without a history of optic neuritis. METHODS: 63 patients with relapsing-remitting MS were included in a two-centre cross-sectional prospective study. All patients underwent retinal examination with spectral domain optical coherence tomography and 1.5 T MRI for determination of normalized brain volume (NBV), white matter volume (NWMV) and grey matter volume (NGMV). RESULTS: Both RNFL and GCL were associated with NBV, NWMV and NGMV in eyes without previous optic neuritis. This association is disrupted in the case of NGMV following optic neuritis. CONCLUSIONS: Both RNFL and GCL as parameters of neuro-axonal damage are comparably linked to whole brain as well as white and grey matter atrophy. An event of optic neuritis interferes with this relation, adding further damage to the optic nerve and disrupting especially an association with grey matter.

Zimmermann H; Freing A; Kaufhold F; Gaede G; Bohn E; Bock M; Oberwahrenbrock T; Young KL; Dörr J; Wuerfel JT; Schippling S; Paul F; Brandt AU

2013-04-01

 
 
 
 
221

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

UK PubMed Central (United Kingdom)

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

Wylegala E; Nowinska AK; Wroblewska-Czajka E; Janiszewska D

2013-09-01

222

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

Science.gov (United States)

Optical coherence tomography has already been proven to be useful for pre- and post-surgical anterior eye segment assessment, especially in lamellar keratoplasty procedures. There is no evidence for intraoperative usefulness of optical coherence tomography (OCT). We present a case report of the intraoperative donor disc attachment assessment with spectral-domain optical coherence tomography in case of Descemet stripping automated endothelial keratoplasty (DSAEK) surgery combined with corneal incisions. The effectiveness of the performed corneal stab incisions was visualized directly by OCT scan analysis. OCT assisted DSAEK allows the assessment of the accuracy of the Descemet stripping and donor disc attachment. PMID:24104711

Wylegala, Edward; Nowinska, Anna K; Wroblewska-Czajka, Ewa; Janiszewska, Dominika

2013-09-01

223

Correlation of endoscopic optical coherence tomography with histology  

Science.gov (United States)

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

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

2000-04-01

224

Optical coherence tomography in the diagnosis and management of optic neuritis and multiple sclerosis.  

Science.gov (United States)

Optic neuritis (ON) is an inflammatory optic nerve injury, which is strongly associated with multiple sclerosis (MS). Optical coherence tomography (OCT) has the potential to provide a reliable means of capturing axonal deficits, which can be paired to tests of visual function to provide a structural-functional paradigm of brain injury. In this respect, the eye provides a unique view into the effects of central nervous system inflammation, which may enhance the understanding of disease mechanisms that contribute to neurological disability in MS. This review addresses the published experience with OCT in the diagnosis and treatment of patients with ON and MS, and discusses the applications of OCT in ongoing clinical trials. The potential gains and limitations of spectral-domain OCT as an evolving technology and surrogate marker of axonal brain injury are also discussed. PMID:21790109

Costello, Fiona E; Klistorner, Alexander; Kardon, Randy

2011-07-01

225

Optical coherence tomography in the diagnosis and management of optic neuritis and multiple sclerosis.  

UK PubMed Central (United Kingdom)

Optic neuritis (ON) is an inflammatory optic nerve injury, which is strongly associated with multiple sclerosis (MS). Optical coherence tomography (OCT) has the potential to provide a reliable means of capturing axonal deficits, which can be paired to tests of visual function to provide a structural-functional paradigm of brain injury. In this respect, the eye provides a unique view into the effects of central nervous system inflammation, which may enhance the understanding of disease mechanisms that contribute to neurological disability in MS. This review addresses the published experience with OCT in the diagnosis and treatment of patients with ON and MS, and discusses the applications of OCT in ongoing clinical trials. The potential gains and limitations of spectral-domain OCT as an evolving technology and surrogate marker of axonal brain injury are also discussed.

Costello FE; Klistorner A; Kardon R

2011-07-01

226

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

Science.gov (United States)

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

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

2010-01-01

227

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

UK PubMed Central (United Kingdom)

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 Y; Zawadzki RJ; Sarunic MV

2013-05-01

228

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

229

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

230

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

Directory of Open Access Journals (Sweden)

Full Text Available Jonathan H Tzu, Harry W Flynn Jr, Audina M Berrocal, William E Smiddy, Timothy G Murray, Yale L FisherDepartment of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USAPurpose: The purpose of this retrospective study was to evaluate the characteristic features, including spectral-domain optical coherence tomography (SD-OCT), clinical course, and outcome of treatment if given for patients with optic disc pit maculopathy.Methods: We investigated a consecutive series of patients with a diagnosis of optic pit maculopathy treated between 2001 and 2012 at the Bascom Palmer Eye Institute. Patients were divided into two main groups, ie, patients who were observed without surgery and patients who received surgical intervention. The main outcome measures were presenting and final visual acuity, and changes in SD-OCT imaging were recorded. Other data including age, gender, eye, age of onset, length of follow-up, location of optic pit, and location of fluid by OCT were also recorded.Results: On OCT, 67% (12/18) of the eyes showed schisis-like cavities, 22% (4/18) had only subretinal fluid, and 17% (3/18) had only a schisis-like cavity without subretinal fluid. In the patients managed by observation, visual acuity was ?20/200 in 6/8 eyes initially and 6/8 eyes at last follow-up. Ten of 18 patients received either focal laser, surgery or both. Six of 10 eyes undergoing surgery had initial visual acuity ? 20/200, and 8 of 10 eyes undergoing surgery had a visual acuity of ?20/200 at last follow-up.Conclusion: In this study, many eyes were observed and remained stable during follow-up. In eyes with reduced vision, surgical intervention produced variable outcomes, and persistent intraretinal/subretinal fluid was a common occurrence.Keywords: optic pit maculopathy, spectral-domain optical coherence tomography

Tzu JH; Flynn Jr HW; Berrocal AM; Smiddy WE; Murray TG; Fisher YL

2013-01-01

231

[Optical coherence tomography in diagnosis of retinal diseases in children and adolescents].  

UK PubMed Central (United Kingdom)

This report describes the new optical technique of optical coherence tomography (OCT) for imaging eye fundus. OCT is noninvasive, capable of high-resolution of 10 to 17 microns imaging of biological tissue. It has been used, to investigate several ocular diseases in children and adolescents. These include macular disease, glaucoma, optic nerve disorders, and myopia.

Mrugacz M; Bakunowicz-?azarczyk A

2004-01-01

232

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

Science.gov (United States)

Purpose To assess the difference in retinal nerve fiber layer (RNFL) and optic disc algorithms between glaucomatous and normal Arab subjects using optical coherence tomography (OCT). Methods RNFL thickness and optic disc parameters were obtained in 65 patients aged 50.1 ± 7.7 years. Percentage differences in all parameters were calculated and analyzed between groups. Results The mean RNFL thickness around the disc and at all quadrants was significantly thinner in glaucomatous eyes than in normal eyes (P optic disc.

Zeried, Ferial M; Osuagwu, Uchechukwu L

2013-01-01

233

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

UK PubMed Central (United Kingdom)

ABSTRACT. 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.

Genina EA; Bashkatov AN; Kolesnikova EA; Basko MV; Terentyuk GS; Tuchin VV

2014-02-01

234

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

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: The aim was to study optic nerve head (ONH) parameters in normal Indian eyes using spectral domain optical coherence tomography (OCT)/scanning laser ophthamoscope (SLO). Materials and Methods: One hundred and fifty-seven eyes of 157 normal subjects of various age groups underwent ONH imaging with spectral OCT/SLO and the parameters obtained were correlated with disc size. The effect of age, gender, and refractive error on various ONH parameters were also studied. Results: The mean optic disc area was 3.36 ± 0.64 mm 2 (range, 2.13-5.08 mm 2 ), mean rim area was 2.49 ± 0.58 mm 2 (range, 1.20-3.62 mm 2 ), and mean cup area was 1.10 ± 0.75 mm 2 (range, 0-3.07 mm 2 ). The disc area showed significant positive correlation with the rim area, cup area, horizontal cup disc ratio, vertical cup disc ratio, cup disc area ratio, mean cup depth, and maximum cup depth (P r = -0.25, P Conclusions: The quantitative measurement of ONH topography obtained with this study provides a normative database for an Indian population with spectral OCT/SLO. As optic disc area influences ONH topography, disc size should to be considered when evaluating optic disc for progressive optic neuropathies such as glaucoma.

Mansoori Tarannum; Viswanath Kalluri; Balakrishna Nagalla

2011-01-01

235

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 , cup area 0.87 ± 0.45 mm 2 , neuroretinal rim area 1.78 ± 0.55 mm 2 and cup to disc area ratio 0.33 ± 0.15. There was no significant difference in the measurements between males and females. There was no significant correlation with respect to age and refractive errors ranging from -5.0 to +3.0 diopters of spherical equivalent. Conclusion: Our study provides a normative database for the various optic disc topographic measurements and its variations with age, sex and refractive error in normal Indian eyes using OCT.

Dacosta Shaun; Bilal Sheena; Rajendran Babu; Janakiraman P

2008-01-01

236

Lens thickness with age and accommodation by optical coherence tomography.  

UK PubMed Central (United Kingdom)

PURPOSE: To utilize time-domain optical coherence tomography (OCT) to measure changes in the crystalline lens with age and accommodation. METHODS: A cross-sectional study of pre-presbyopic and presbyopic subjects was conducted. Amplitude of accommodation was measured with the push-up test. Objective accommodation was measured with the Grand Seiko auto-refractor and a Badal lens system. Lens thickness was measured with the Zeiss Visante OCT and an internal optometer. The data were analysed using correlation coefficients, linear regression, and by calculating the average change in lens thickness per diopter change in objective accommodation. RESULTS: Twenty-two subjects between the ages of 36 and 50 years completed the study. Subjective amplitude of accommodation ranged from 2.17 to 6.38 D. Objective accommodation ranged from 0.22 to 4.56 D. The mean lens thickness was 4.05+/-0.20 mm. The mean change in lens thickness for up to a 5-D accommodative stimulus ranged from 0.01 to 0.26 mm. The correlation coefficients were: age and subjective accommodation, r= -0.74; age and objective accommodation, r= -0.84; change in lens thickness and age, r= -0.65; change in lens thickness and subjective accommodation, r=0.74; change in lens thickness and objective accommodation, r=0.64; objective and subjective accommodation, r=0.82 (all p<0.01). An increase in lens thickness of 21 microm per year of age was determined by linear regression. For the subjects who showed at least 1 D of accommodative response on the Grand Seiko auto-refractor, there was an increase of 51+/-19 microm per dioptre of accommodation. CONCLUSIONS: Optical coherence tomography is a non-invasive technique that can be used to quantify changes in the thickness of the crystalline lens. Subjective and objective measurements of accommodation, as well as age, were robustly correlated with the measured changes in lens thickness. Lens thickness changes with age and accommodation as measured with the Visante OCT compare well with previous findings using Scheimpflug photography and ultrasound.

Richdale K; Bullimore MA; Zadnik K

2008-09-01

237

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

UK PubMed Central (United Kingdom)

Secondary decay (caries) under ceramic orthodontic brackets remains a significant dental problem and near infrared cross-polarization optical coherence tomography (CP-OCT) has the potential to detect underlying demineralization. The purpose of this study was to determine the effect of crystalline structure and chemical composition of ceramic brackets on CP-OCT imaging. Four ceramic brackets types, which were divided into monocrystalline and polycrystalline, were examined using CP-OCT. The results of this study demonstrated that the crystallinity of the ceramic brackets affected the 1310 nm CP-OCT imaging with the greatest attenuation seen in polycrystalline alumina brackets. The alumina polycrystalline bracket materials had significantly higher attenuation and scattering than alumina monocrystalline brackets (p?optical coherence tomography (CP-OCT) has potential to effectively image through portions of ceramic brackets; however, further investigation into the optical effects of resin integration in the base portion of the brackets is warranted. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2013.

Isfeld DM; Aparicio C; Jones RS

2013-09-01

238

Boundary conditions in the problems of optical tomography of tensor fields  

International Nuclear Information System (INIS)

[en] The role of boundary conditions for the correct formulation photoelasticity problems based on the restoration of tensor fields by means of optical tomography is presented in this article. (orig.)

1992-01-01

239

Algorithmic depth compensation improves quantification and noise suppression in functional diffuse optical tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Accurate depth localization and quantitative recovery of a regional activation are the major challenges in functional diffuse optical tomography (DOT). The photon density drops severely with increased depth, for which conventional DOT reconstruction yields poor depth localization and quantitative re...

Tian, Fenghua; Niu, Haijing; Khadka, Sabin; Lin, Zi-Jing; Liu, Hanli

240

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; P. van Thienen; H. Beverloo

2013-01-01

 
 
 
 
241

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

International Nuclear Information System (INIS)

[en] 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

2009-01-01

242

Predicting tumor response in breast cancer patients using diffuse optical tomography  

Science.gov (United States)

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

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

2013-06-01

243

[Corneal flap analysis after LASIK and femto-LASIK using optical coherence tomography and optical sections].  

Science.gov (United States)

Two groups of patients were enrolled into the study, each group included 15 patients (30 eyes). Evolution 3E mechanical microkeratome ("Moria") was used to create LASIK flaps in the 1st group. VISUMAX laser microkeratome ("Carl Zeiss Meditec") was used in the 2nd group. Optical coherence tomography showed irregularity of flap thickness in the 1st group. In the 2nd group flap thickness was regular. According to Pentacam data the posterior corneal surface had no postoperative changes in both groups. PMID:23210338

Kostin, O A; Rebrikov, S V; Ovchinnikov, A I; Stepanov, A A

244

[Intracranial tumors in patients referred for optical coherence tomography examination as glaucoma suspects: case report].  

UK PubMed Central (United Kingdom)

Optical coherence tomography (OCT) has proved to be a very valuable tool in the assessment of patients with glaucoma. In this report, intracranial tumors were discovered in two glaucoma suspects referred for diagnostic confirmation by OCT - a clivus chordoma and a craniopharyngeoma. Optical coherence tomography findings - marked asymmetrical diffuse attenuation of the peripapillary nerve fiber layer in nasal and temporal sectors - raised concerns about lesions in chiasmatic region and permitted the timely diagnosis of these intraocular tumors.

Biccas Neto L; Mesquita AS

2009-09-01

245

Optical coherence tomography in patients with acute coronary syndrome.  

Science.gov (United States)

Optical coherence tomography (OCT) is a novel invasive imaging technology that allows in vivo assessment of the coronary wall with high resolution (approximately 15 micron). OCT offers a number of specific diagnostic features to study culprit lesions in patients suffering from acute coronary syndrome (ACS). Clinical OCT studies in patients presenting with ACS were able to confirm post mortem histopathology findings and shed light on the dynamic nature of atherosclerotic plaque formation, modification and rupture. OCT confirmed in vivo that the incidence of target lesion and remote TCFA varies with the clinical syndrome of the patients, being most pronounced in patients with acute myocardial infarction as compared to patients with stable angina. In culprit lesions where rupture of a fibrous cap has been documented, the fibrous cap thickness was in the range of 50 micron and macrophage density was elevated. Encouraging small scale clinical studies evaluated treatment effects in this population. OCT was used to demonstrate statin effects on fibrous cap thickness or the effects of different stent designs. The markedly improved image quality and user-friendliness of the second generation, Fourier-domain OCT, will allow large scale clinical application and thus, will increase our understanding of the pathophysiology and the prevention of ACS. PMID:20542823

Regar, Evelyn; van Soest, Gijs; Bruining, Nico; Constantinescu, Alina A; van Geuns, Robert J; van der Giessen, Wim; Serruys, Patrick W

2010-05-01

246

Optical coherence tomography classification of diabetic cystoid macular edema  

Science.gov (United States)

Purpose 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 mellitus of duration from 5 to 20 years. All patients were diagnosed to have CME, as assessed by OCT, with measurement of the vertical size of the largest macular cyst and maximum macular thickness, and the relation between them. Results Patients were divided into four groups. Eyes with cysts less than 30% of macular thickness were considered to have CME I (n = 4, 3.84%), while those between 30% and 60% were considered to have CME II (n = 62, 59.62%). Eyes with cysts between 60% and 90% of macular thickness were considered to have CME III (n = 36, 34.62%). CME IV was diagnosed when the size of the cyst became more than 90% of the macular thickness, and this was encountered in two eyes (1.92%). Conclusions OCT is a useful technique for quantitative measurement and helps in better anatomical characterization of CME, and this classification of diabetic CME may be of value in classification of CME due to causes other than diabetes.

Helmy, Yasser M; Allah, Heba R Atta

2013-01-01

247

Spectral domain optical coherence tomography features of subretinal cysticercus cyst.  

UK PubMed Central (United Kingdom)

A 31-year-old man of Asian descent presented with loss of vision in his right eye from 6 months earlier. Best corrected visual acuity (BCVA) was limited to light perception in the right eye and was 6/6, N6 in the left one. Slit lamp examination revealed normal anterior segments bilaterally. Intraocular pressure was 8 and 14 mmHg in the right and left eyes, respectively. Fundus examination in the right eye showed a large subretinal cysticercus cyst, accompanied by total retinal detachment (RD), severe extensive subretinal fibrosis and membranes (Fig. 1A). B-scan ultrasound (Alcon Ultrascan, Alcon Laboratories, Fort Worth, Texas, USA) images illustrated total RD with a hyperechoic area within the cystic cavity suggestive of cysticercus scolex (Fig. 1B). Spectral domain optical coherence tomography (OCT) (Topcon 3D OCT-2000, Topcon Medical Systems, Oakland, New Jersey, USA) demonstrated a highly reflective cyst wall and a more hyper-reflective dome-shaped structure within the wall suggestive of the scolex (Fig. 1C). The posterior extent of the cyst could not be visualized due to its large size. T1-weighted contrast-enhanced magnetic resonance imaging (MRI) of the brain demonstrated a ring-shaped enhancing lesion in the left cerebellar hemisphere with perilesional brain edema suggestive of neurocysticercosis (Fig. 1D). The patient was referred to a neurophysician and received a three month course of oral albendazole and steroids. Eventually, he was recommended for follow-up care.

Raval V; Khetan V

2012-10-01

248

Statistics of optical coherence tomography data from human retina.  

UK PubMed Central (United Kingdom)

Optical coherence tomography (OCT) has recently become one of the primary methods for noninvasive probing of the human retina. The pseudoimage formed by OCT (the so-called B-scan) varies probabilistically across pixels due to complexities in the measurement technique. Hence, sensitive automatic procedures of diagnosis using OCT may exploit statistical analysis of the spatial distribution of reflectance. In this paper, we perform a statistical study of retinal OCT data. We find that the stretched exponential probability density function can model well the distribution of intensities in OCT pseudoimages. Moreover, we show a small, but significant correlation between neighbor pixels when measuring OCT intensities with pixels of about 5 microm. We then develop a simple joint probability model for the OCT data consistent with known retinal features. This model fits well the stretched exponential distribution of intensities and their spatial correlation. In normal retinas, fit parameters of this model are relatively constant along retinal layers, but varies across layers. However, in retinas with diabetic retinopathy, large spikes of parameter modulation interrupt the constancy within layers, exactly where pathologies are visible. We argue that these results give hope for improvement in statistical pathology-detection methods even when the disease is in its early stages.

Grzywacz NM; de Juan J; Ferrone C; Giannini D; Huang D; Koch G; Russo V; Tan O; Bruni C

2010-06-01

249

Optical coherence tomography velocimetry in controlled shear flow.  

UK PubMed Central (United Kingdom)

Doppler-shift optical coherence tomography with infrared light was used to probe the velocity profiles of concentrated solutions of complex fluids with samples experiencing steady-state shear flow. The apparatus is sensitive to a velocity range of 0.7-330 mm/s probing very small volumes of material (quasicylindrical volume elements of 9-?m length and 11-?m radius with 3.4-picoliter volumes) inside a plate-plate rheometer with a total sample volume of ~100-1000 ?L. The technique can scan the flow in the plane perpendicular to the shear direction, building up a two-dimensional map of the velocity flow field. The use of a coherence gate with a broad-band infrared source (9-?m coherence length, 1300-nm wavelength) allows opaque specimens, such as concentrated colloidal suspensions (2% w/w) and margarine, to be probed. We observe the phenomena of wall slip (margarine) and shear banding (polyacrylamide, a linear flexible polyelectrolyte) using this technique.

Harvey M; Waigh TA

2011-03-01

250

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.

2008-03-01

251

Evaluation of oral vascular anomalies using optical coherence tomography.  

UK PubMed Central (United Kingdom)

Optical coherence tomography (OCT) is a new method of biomedical imaging that can generate high-resolution, cross-sectional images of microstructures. The purpose of this study was to present the first OCT images of oral vascular anomalies using a new advanced OCT scanner that we have developed, and to discuss the application of our system for oral soft tissues. Knowledge of the size and area of the vascular structures can be useful for the diagnosis and choice of the best treatment. Before excision, oral vascular malformations were assessed by OCT in vivo. Histopathological sections were taken and compared with the OCT images to make clinicopathological correlations. OCT provided clear images of all the vascular lesions examined. Oval to roundish, signal-poor areas sharply demarcated by a surrounding signal-rich layer correlated well with the histopathological diagnosis. OCT images provide information about subsurface structure non-invasively that is otherwise obtainable only by examination of a biopsy specimen. The analysis of oral vascular lesions by OCT provides new insights into non-invasive diagnosis and can be helpful in the selection of the most appropriate treatment.

Ozawa N; Sumi Y; Chong C; Kurabayashi T

2009-12-01

252

In vivo feasibility of endovascular Doppler optical coherence tomography.  

UK PubMed Central (United Kingdom)

Feasibility of detecting intravascular flow using a catheter based endovascular optical coherence tomography (OCT) system is demonstrated in a porcine carotid model in vivo. The effects of A-line density, radial distance, signal-to-noise ratio, non-uniform rotational distortion (NURD), phase stability of the swept wavelength laser and interferometer system on Doppler shift detection limit were investigated in stationary and flow phantoms. Techniques for NURD induced phase shift artifact removal were developed by tracking the catheter sheath. Detection of high flow velocity (~51 cm/s) present in the porcine carotid artery was obtained by phase unwrapping techniques and compared to numerical simulation, taking into consideration flow profile distortion by the eccentrically positioned imaging catheter. Using diluted blood in saline mixture as clearing agent, simultaneous Doppler OCT imaging of intravascular flow and structural OCT imaging of the carotid artery wall was feasible. To our knowledge, this is the first in vivo demonstration of Doppler imaging and absolute measurement of intravascular flow using a rotating fiber catheter in carotid artery.

Sun C; Nolte F; Cheng KH; Vuong B; Lee KK; Standish BA; Courtney B; Marotta TR; Mariampillai A; Yang VX

2012-10-01

253

Optical coherence tomography and ultrasound biomicroscopy imaging of opaque corneas.  

UK PubMed Central (United Kingdom)

PURPOSE: The purpose was to determine the interchangeability of ultrasound biomicroscopy (UBM) and anterior segment optical coherence tomography (AS-OCT) for corneal opacity depth measurement. METHODS: Twenty-six eyes of 26 consecutive patients with corneal opacities were examined by both AS-OCT and UBM. The corneal thickness and the corneal opacity depth were measured and compared. The interchangeability was determined by Bland-Altman plotting. RESULTS: The difference in the full corneal thickness and in the corneal opacity depth between OCT and UBM was 5 ± 7 ?m and -1 ± 8 ?m, respectively. There were strong correlations and no significant differences between the paired parameters (all r > 0.99, P < 0.01). The limits of agreement were 5 ± 14 ?m for the corneal thickness and -1 ± 14.8 ?m for the corneal opacity depth. CONCLUSIONS: AS-OCT and UBM may be used interchangeably for measuring both full corneal thickness and corneal opacity depth in patients with corneal opacity.

Zhou SY; Wang CX; Cai XY; Huang D; Liu YZ

2013-04-01

254

Diagnosis of oral submucous fibrosis with optical coherence tomography  

Science.gov (United States)

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

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

2009-09-01

255

Automatic characterization of neointimal tissue by intravascular optical coherence tomography.  

UK PubMed Central (United Kingdom)

Intravascular optical coherence tomography (IVOCT) is rapidly becoming the method of choice for assessing vessel healing after stent implantation due to its unique axial resolution <20???m. The amount of neointimal coverage is an important parameter. In addition, the characterization of neointimal tissue maturity is also of importance for an accurate analysis, especially in the case of drug-eluting and bioresorbable stent devices. Previous studies indicated that well-organized mature neointimal tissue appears as a high-intensity, smooth, and homogeneous region in IVOCT images, while lower-intensity signal areas might correspond to immature tissue mainly composed of acellular material. A new method for automatic neointimal tissue characterization, based on statistical texture analysis and a supervised classification technique, is presented. Algorithm training and validation were obtained through the use of 53 IVOCT images supported by histology data from atherosclerotic New Zealand White rabbits. A pixel-wise classification accuracy of 87% and a two-dimensional region-based analysis accuracy of 92% (with sensitivity and specificity of 91% and 93%, respectively) were found, suggesting that a reliable automatic characterization of neointimal tissue was achieved. This may potentially expand the clinical value of IVOCT in assessing the completeness of stent healing and speed up the current analysis methodologies (which are, due to their time- and energy-consuming character, not suitable for application in large clinical trials and clinical practice), potentially allowing for a wider use of IVOCT technology.

Ughi GJ; Steigerwald K; Adriaenssens T; Desmet W; Guagliumi G; Joner M; D'hooge J

2014-02-01

256

Speckle texture analysis of optical coherence tomography images  

Science.gov (United States)

Optical coherence tomography (OCT) is an imaging technique based on the low coherence interferometry, in which signals are obtained based on the coherent addition of the back reflected light from the sample. Applying computational methods and automated algorithms towards the classification of OCT images allows a further step towards enhancing the clinical applications of OCT. One attempt towards classification could be achieved by statistically analyzing the texture of the noisy granular patterns - speckles that make the OCT images. An attempt has been made to quantify the scattering effects based on the speckle texture patterns the scatterers produce. Statistical inference is drawn from the textural analysis of the features based on the spatial intensity distribution on the agar phantoms with different concentration of Intralipid solutions. This preliminary study conducted on agar-Intralipid solution has showed us that it is possible to differentiate between different types of scatterers based on the speckle texture studies. The texture analysis has also been extended in an attempt to identify the invasion of melanoma cell into tissue engineered skin. However using the same approach of texture analysis, we have not obtained satisfactory results for carrying on with the computer-based identification of the invasion of the melanoma in the tissue engineered skin, the reason for which has to be further studied and investigated upon.

Kasaragod, Deepa K.; Lu, Zenghai; Smith, Louise E.; Matcher, Stephen J.

2010-09-01

257

Optical coherence tomography classification of diabetic cystoid macular edema.  

UK PubMed Central (United Kingdom)

PURPOSE: 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 mellitus of duration from 5 to 20 years. All patients were diagnosed to have CME, as assessed by OCT, with measurement of the vertical size of the largest macular cyst and maximum macular thickness, and the relation between them. RESULTS: Patients were divided into four groups. Eyes with cysts less than 30% of macular thickness were considered to have CME I (n = 4, 3.84%), while those between 30% and 60% were considered to have CME II (n = 62, 59.62%). Eyes with cysts between 60% and 90% of macular thickness were considered to have CME III (n = 36, 34.62%). CME IV was diagnosed when the size of the cyst became more than 90% of the macular thickness, and this was encountered in two eyes (1.92%). CONCLUSIONS: OCT is a useful technique for quantitative measurement and helps in better anatomical characterization of CME, and this classification of diabetic CME may be of value in classification of CME due to causes other than diabetes.

Helmy YM; Allah HR

2013-01-01

258

The potential of optical coherence tomography for diagnosing meniscal pathology  

Science.gov (United States)

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.

Hang-Yin Ling, Carrie; Pozzi, Antonio; Thieman, Kelley M.; Tonks, Catherine A.; Guo, Shuguang; Xie, Huikai; Horodyski, MaryBeth

2010-04-01

259

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; Upender K. Wali; Sitara Azeem

2013-01-01

260

Thrombosis and morphology of plaque rupture using optical coherence tomography.  

UK PubMed Central (United Kingdom)

BACKGROUND: Thrombosis following plaque rupture is the main cause of acute coronary syndrome, but not all plaque ruptures lead to thrombosis. There are limited in vivo data on the relationship between the morphology of ruptured plaque and thrombosis. METHODS: We used optical coherence tomography (OCT) to investigate the morphology of plaque rupture and its relation to coronary artery thrombosis in patients with coronary heart disease. Forty-two patients with coronary artery plaque rupture detected by OCT were divided into two groups (with or without thrombus) and the morphological characteristics of ruptured plaque, including fibrous cap thickness and broken cap site, were recorded. RESULTS: The fibrous cap of ruptured plaque with thrombus was significantly thinner compared to caps without thrombus ((57.00 ± 17.00) µm vs. (96.00 ± 48.00) µm; P = 0.0076). CONCLUSIONS: Plaque rupture associated with thrombosis occurs primarily in plaque covered by a thin fibrous cap. Thick fibrous caps are associated with greater stability of ruptured plaque.

Guo J; Chen YD; Tian F; Liu HB; Chen L; Sun ZJ; Ren YH; Jin QH; Liu CF; Han BS; Gai LY; Yang TS

2013-03-01

 
 
 
 
261

Optical coherence tomography: clinical applications in medical practice.  

UK PubMed Central (United Kingdom)

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.

Al-Mujaini A; Wali UK; Azeem S

2013-03-01

262

Retinal and choroidal intravascular spectral-domain optical coherence tomography.  

Science.gov (United States)

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 reflectivity faded when blood flow was lower or higher than normal or at oblique angles to the line of sight. In conclusion, SD-OCT scans of the vessels in the posterior pole of the eye may assist the clinical assessment of gross abnormalities of ocular blood flow, e.g. in carotid artery stenosis. PMID:23552098

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

2013-04-01

263

Wavelet domain compounding for speckle reduction in optical coherence tomography.  

Science.gov (United States)

ABSTRACT. 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

264

Wavelet domain compounding for speckle reduction in optical coherence tomography.  

UK PubMed Central (United Kingdom)

ABSTRACT. 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.

Xu J; Ou H; Sun C; Chui PC; Yang VX; Lam EY; Wong KK

2013-09-01

265

OCT y fototoxicidad macular/ Optical coherence tomography and macular phototoxicity  

Scientific Electronic Library Online (English)

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

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

2008-04-01

266

OCT y fototoxicidad macular Optical coherence tomography and macular phototoxicity  

Directory of Open Access Journals (Sweden)

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

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

2008-01-01

267

Automated contact lens measurement using optical coherence tomography  

Science.gov (United States)

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

Davidson, Bryan R.; Barton, Jennifer K.

2009-02-01

268

Imaging of artificial cartilage with optical coherence tomography  

Science.gov (United States)

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

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

2008-03-01

269

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

270

Monitoring remineralization of enamel subsurface lesions by optical coherence tomography.  

UK PubMed Central (United Kingdom)

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

Mandurah MM; Sadr A; Shimada Y; Kitasako Y; Nakashima S; Bakhsh TA; Tagami J; Sumi Y

2013-04-01

271

All fiber optics circular-state swept source polarization-sensitive optical coherence tomography.  

UK PubMed Central (United Kingdom)

ABSTRACT. A swept source (SS)-based circular-state (CS) polarization-sensitive optical coherence tomography (PS-OCT) constructed entirely with polarization-maintaining fiber optics components is proposed with the experimental verification. By means of the proposed calibration scheme, bulk quarter-wave plates can be replaced by fiber optics polarization controllers to, therefore, realize an all-fiber optics CS SSPS-OCT. We also present a numerical dispersion compensation method, which can not only enhance the axial resolution, but also improve the signal-to-noise ratio of the images. We demonstrate that this compact and portable CS SSPS-OCT system with an accuracy comparable to bulk optics systems requires less stringent lens alignment and can possibly serve as a technology to realize PS-OCT instrument for clinical applications (e.g., endoscopy). The largest deviations in the phase retardation (PR) and fast-axis (FA) angle due to sample probe in the linear scanning and a rotation angle smaller than 65 deg were of the same order as those in stationary probe setups. The influence of fiber bending on the measured PR and FA is also investigated. The largest deviations of the PR were 3.5 deg and the measured FA change by ?12 to 21 deg. Finally, in vivo imaging of the human fingertip and nail was successfully demonstrated with a linear scanning probe.

Lin H; Kao MC; Lai CM; Huang JC; Kuo WC

2014-02-01

272

All fiber optics circular-state swept source polarization-sensitive optical coherence tomography.  

UK PubMed Central (United Kingdom)

A swept source (SS)-based circular-state (CS) polarization-sensitive optical coherence tomography (PS-OCT) constructed entirely with polarization-maintaining fiber optics components is proposed with the experimental verification. By means of the proposed calibration scheme, bulk quarter-wave plates can be replaced by fiber optics polarization controllers to, therefore, realize an all-fiber optics CS SSPS-OCT. We also present a numerical dispersion compensation method, which can not only enhance the axial resolution, but also improve the signal-to-noise ratio of the images. We demonstrate that this compact and portable CS SSPS-OCT system with an accuracy comparable to bulk optics systems requires less stringent lens alignment and can possibly serve as a technology to realize PS-OCT instrument for clinical applications (e.g., endoscopy). The largest deviations in the phase retardation (PR) and fast-axis (FA) angle due to sample probe in the linear scanning and a rotation angle smaller than 65 deg were of the same order as those in stationary probe setups. The influence of fiber bending on the measured PR and FA is also investigated. The largest deviations of the PR were 3.5 deg and the measured FA change by ~12 to 21 deg. Finally, in vivo imaging of the human fingertip and nail was successfully demonstrated with a linear scanning probe.

Lin H; Kao MC; Lai CM; Huang JC; Kuo WC

2014-02-01

273

Optical coherence tomography for debonding evaluation: an in-vitro qualitative study.  

UK PubMed Central (United Kingdom)

INTRODUCTION: The purpose of this research was to demonstrate the potential of the optical coherence tomography technique on the evaluation of changes and damages in the enamel structure caused by debonding and cleanup procedures. METHODS: Twin metal and ceramic brackets were bonded to the labial enamel surfaces of 120 incisors; the brackets were debonded 24 hours later. The anterior surfaces of the teeth were scanned, and optical coherence tomography images were captured in 2-dimensional and 3-dimensional modes before and after debonding and cleanup. A commercial spectral domain optical coherence tomography system with a 5-?m axial spatial resolution was used. The system is based on the Michelson interferometer setup. It is connected to a preconfigured personal computer, and the images are captured with a scanner probe that controls the light beam position at the sample. A total of 960 images were evaluated. RESULTS: The analysis of the 2-dimensional and 3-dimensional images obtained with optical coherence tomography allows observation and evaluation of adhesive remnants, enamel damage, and superficial aspects of enamel from different methods of adhesive remnant removal. The 2-dimensional optical coherence tomography analysis allows in-depth observation of the adhesive remnant layer. CONCLUSIONS: Optical coherence tomography can be a powerful tool for academic and clinical applications for the evaluation of debonding procedures.

Leão Filho JC; Braz AK; de Souza TR; de Araujo RE; Pithon MM; Tanaka OM

2013-01-01

274

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, studie...

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

275

Diagnosing preperimetric glaucoma with spectral domain optical coherence tomography.  

UK PubMed Central (United Kingdom)

PURPOSE: To evaluate the diagnostic accuracy of spectral domain optical coherence tomography (SD-OCT) for detection of preperimetric glaucoma and compare it with the performance of confocal scanning laser ophthalmoscopy (CSLO). DESIGN: Cohort study. PARTICIPANTS: A cohort of 134 eyes of 88 glaucoma suspects based on the appearance of the optic disc. METHODS: Patients were recruited from the Diagnostic Innovations in Glaucoma Study (DIGS). All eyes underwent retinal nerve fiber layer (RNFL) imaging with Spectralis SD-OCT (Heidelberg Engineering, Carlsbad, CA) and topographic imaging with Heidelberg Retinal Tomograph III (HRT-III) (Heidelberg Engineering) CSLO within 6 months of each other. All patients had normal visual fields at the time of imaging and were classified on the basis of history of documented stereophotographic evidence of progressive glaucomatous change in the appearance of the optic nerve occurring before the imaging sessions. MAIN OUTCOME MEASURES: Areas under the receiver operating characteristic curves (AUCs) were calculated to summarize diagnostic accuracies of the SD-OCT and CSLO. Likelihood ratios (LRs) were reported using the diagnostic categorization provided by each instrument after comparison to its normative database. RESULTS: Forty-eight eyes of 42 patients had evidence of progressive glaucomatous change and were included in the preperimetric glaucoma group. Eighty-six eyes of 46 patients without any evidence of progressive glaucomatous change followed untreated for an average of 14.0 ± 3.6 years were included in the control group. The parameter with the largest AUC obtained with the SD-OCT was the temporal superior RNFL thickness (0.88 ± 0.03), followed by global RNFL thickness (0.86 ± 0.03) and temporal inferior RNFL thickness (0.81 ± 0.04). The parameter with the largest AUC obtained with the CSLO was rim area (0.72 ± 0.05), followed by rim volume (0.71 ± 0.05) and linear cup-to-disk ratio (0.66 ± 0.05). Temporal superior RNFL average thickness measured by SD-OCT performed significantly better than rim area measurements from CSLO (0.88 vs. 0.72; P=0.008). Outside normal limits results for SD-OCT parameters were associated with strongly positive LRs. CONCLUSIONS: The RNFL assessment with SD-OCT performed well in detecting preperimetric glaucomatous damage in a cohort of glaucoma suspects and had a better performance than CSLO.

Lisboa R; Leite MT; Zangwill LM; Tafreshi A; Weinreb RN; Medeiros FA

2012-11-01

276

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.

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

2011-01-01

277

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.

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

2011-01-01

278

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

UK PubMed Central (United Kingdom)

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.

Lee C; Lee SY; Kim JY; Jung HY; Kim J

2011-01-01

279

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

2011-10-10

280

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

International Nuclear Information System (INIS)

A Monte Carlo model has been developed for optical coherence tomography (OCT). A geometrical optics implementation of the OCT probe with low-coherence interferometric detection was combined with three-dimensional stochastic Monte Carlo modelling of photon propagation in the homogeneous sample medium. Optical properties of the sample were selected to simulate intralipid and blood, representing moderately (g=0.7) and highly (g=0.99) anisotropic scattering respectively. For shallow optical depths in simulated intralipid (

1998-01-01

 
 
 
 
281

Electroretinography combined with spectral domain optical coherence tomography to detect retinal damage in shaken baby syndrome.  

Science.gov (United States)

In order to correlate anatomical changes with visual function in shaken baby syndrome, we performed electroretinography and spectral domain optical coherence tomography on a 2-month-old girl and a 9-month-old girl after the retinal hemorrhages absorbed. Both patients had significant abnormalities in spectral domain optical coherence tomography images of the macular area. The amplitudes of the focal macular electroretinograms were more severely decreased than those of the full-field electroretinograms. Combining spectral domain coherence tomography with focal macular electroretinograms might better estimate the functional damage to the macula in patients with shaken baby syndrome. PMID:23871295

Nakayama, Yuri; Yokoi, Tadashi; Sachiko, Nishina; Okuyama, Makiko; Azuma, Noriyuki

2013-07-17

282

An evaluation of meniscal collagenous structure using optical projection tomography.  

UK PubMed Central (United Kingdom)

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

Andrews SH; Ronsky JL; Rattner JB; Shrive NG; Jamniczky HA

2013-07-01

283

Assessment of anterior chamber depth using Visante optical coherence tomography, slitlamp optical coherence tomography, IOL Master, Pentacam and Orbscan IIz.  

UK PubMed Central (United Kingdom)

Aims: To assess and compare the anterior chamber depth (ACD) by different anterior segment imaging techniques. Methods: Eighty healthy eyes of 40 patients were recruited, and 3 consecutive measurements of ACD were determined prospectively utilizing Visante optical coherence tomography (OCT), slitlamp (SL) OCT, IOL Master, Pentacam and Orbscan IIz. The statistical significance of interdevice differences between measurements was evaluated by one-way ANOVA and Bland-Altman analysis. The repeatability of 3 consecutive measurements was analyzed by repeated-measures ANOVA. Results: The mean ACD was 2.98 ± 0.29, 2.85 ± 0.29, 3.33 ± 0.42, 2.93 ± 0.30 and 2.80 ± 0.29 mm with Visante OCT, SL-OCT, IOL Master, Pentacam and Orbscan IIz, respectively. All devices displayed a high intrasession repeatability (repeated-measures ANOVA, p > 0.05). ACD measurements obtained by the IOL Master were significantly greater compared to other devices. ACD values detected by Visante OCT and SL-OCT, Pentacam and Orbscan IIz were not clinically interchangeable, even though no statistically significant difference was detected. Conclusion: Although noncontact ACD measurements using all modalities were easy to handle and demonstrated good repeatability, the tested devices were not regarded as compatible. Hence, the clinician should take the different modalities into consideration during ACD assessment using various devices.

Dinc UA; Gorgun E; Oncel B; Yenerel MN; Alimgil L

2010-01-01

284

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

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish Casos clínicos: Se presentan 3 pacientes con desgarro de epitelio pigmentario retiniano (EPR). En dos de ellos, éste se produjo de manera espontánea, estando el tercero en relación con la fotocoagulación de una neovascularización extrafoveal. Se realizaron angiografías (AGF) y estudio con tomografia óptica de coherencia (OCT) que confirmaron el diagnóstico. Discusión: Existen pocos estudios sobre OCT en desgarro del EPR. Las principales características son: int (more) errupción de la línea hiperreflectante del EPR, hiperreflectividad de la coroides en la zona de ausencia de EPR y doble capa de EPR donde éste está replegado. Es frecuente el desprendimiento de EPR y neurosensorial asociado. Abstract in english Case reports: Three cases of pigmentary epithelial tears are described in this study. One of them was related to previous extrafoveal photocoagulation, whereas the other two were idiopathic. Fluorescein angiography (FA) and optical coherence tomography (OCT) were performed to confirm the clinical 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 inclu (more) ded 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.

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

2007-04-01

285

«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; E. Ferrer-Novella; O. Ruiz-Moreno; F.M. Honrubia-López

2007-01-01

286

System design and optimization of optical coherence tomography  

Science.gov (United States)

Optical coherence imaging, including tomography (OCT) and microscopy (OCM), has been a growing research field in biomedical optical imaging in the last decade. In this imaging modality, a broadband light source, thus of short temporal coherence length, is used to perform imaging via interferometry. A challenge in optical coherence imaging, as in any imaging system towards biomedical diagnosis, is the quantification of image quality and optimization of the system components, both a primary focus of this research. We concentrated our efforts on the optimization of the imaging system from two main standpoints: axial point spread function (PSF) and practical steps towards compact low-cost solutions. Up to recently, the criteria for the quality of a system was based on speed of imaging, sensitivity, and particularly axial resolution estimated solely from the full-width at half-maximum (FWHM) of the axial PSF with the common practice of assuming a Gaussian source power spectrum. As part of our work to quantify axial resolution we first brought forth two more metrics unlike FWHM, which accounted for side lobes in the axial PSF caused by irregularities in the shape of the source power spectrum, such as spectral dips. Subsequently, we presented a method where the axial PSF was significantly optimized by suppressing the side lobes occurring because of the irregular shape of the source power spectrum. The optimization was performed through optically shaping the source power spectrum via a programmable spectral shaper, which consequentially led to suppression of spurious structures in the images of a layered specimen. The superiority of the demonstrated approach was in performing reshaping before imaging, thus eliminating the need for post-data acquisition digital signal processing. Importantly, towards the optimization and objective image quality assessment in optical coherence imaging, the impact of source spectral shaping was further analyzed in a task-based assessment method based on statistical decision theory. Two classification tasks, a signal-detection task and a resolution task, were investigated. Results showed that reshaping the source power spectrum was a benefit essentially to the resolution task, as opposed to both the detection and resolution tasks, and the importance of the specimen local variations in index of refraction on the resolution task was demonstrated. Finally, towards the optimization of OCT and OCM for use in clinical settings, we analyzed the detection electronics stage, which is a crucial component of the system that is designed to capture extremely weak interferometric signals in biomedical and biological imaging applications. We designed and tested detection electronics to achieve a compact and low-cost solution for portable imaging units and demonstrated that the design provided an equivalent performance to the commercial lock-in amplifier considering the system sensitivity obtained with both detection schemes.

Akcay, Avni Ceyhun

287

Evaluation of morning glory syndrome with spectral optical coherence tomography and echography.  

UK PubMed Central (United Kingdom)

PURPOSE: To evaluate eyes affected by morning glory syndrome (MGS) with spectral-domain optical coherence tomography (SD OCT) and echography. DESIGN: Prospective case series. PARTICIPANTS: Nineteen patients (22 eyes) with MGS observed at the Eye Department, University of Naples Federico II, Naples, Italy. METHODS: All patients underwent a complete ophthalmologic examination that included best-correct visual acuity, fundus photography, and echography. Nine patients underwent SD OCT and high-frequency B-scan echography (20 MHz). MAIN OUTCOME MEASURES: Spectral-domain optical coherence tomography and echographic findings in MGS. RESULTS: Spectral-domain optical coherence tomography revealed retinal detachment in the conus area of 5 eyes: 4 with noncontractile MGS (NCMGS) and 1 with contractile MGS (CMGS). There was evidence of a retinal break in only 2 cases. All 5 eyes had an abnormal communication between the subarachnoid space and the subretinal space. Spectral-domain optical coherence tomography did not reveal differences between CMGS and NCMGS. Echographic examination did not reveal any anatomic abnormalities of the optic nerve or orbit. CONCLUSIONS: Spectral-domain optical coherence tomography provides more information than echography about the posterior pole, whereas echographic examination is the only technique that can confirm the anatomic integrity of the optic nerve in the orbital wall. Retinal detachment in MGS generally is ascribed to abnormal communication between the subretinal and subarachnoid or vitreous compartments. These data suggest that myopialike retinal detachment without a retinal break may result from tissue stretching around the peripapillary conus.

Cennamo G; de Crecchio G; Iaccarino G; Forte R; Cennamo G

2010-06-01

288

Comparison of in vivo assessment of vulnerable plaque by 64-slice multislice computed tomography versus optical coherence tomography.  

Science.gov (United States)

The aim of this study was to investigate the possibility of 64-slice multislice computed tomography (MSCT) to detect vulnerable plaque derived by optical coherence tomography. From September 2007 through December 2009, 122 lesions in 81 patients were evaluated by 64-slice MSCT and optical coherence tomography. Based on optical coherence tomographic findings, lesions were classified as thin-capped fibroatheroma (TCFA; n=37) and non-TCFA (n=85). Mean computed tomographic density value of the lesion was lower and remodeling index was larger in the TCFA group (44.9 ± 19.2 vs 78.7 ± 25.0 HU, p TCFA group (65% vs 16%, pTCFA were mean computed tomographic density value ?62.4 HU (odds ratio 8.20, 95% confidential interval 2.49 to 27.0, p=0.0005), remodeling index ?1.08 (odds ratio 6.10, 95% confidential interval 2.04 to 18.2, p=0.0012), and signet ringlike appearance (odds ratio 6.33, 95% confidential interval 2.03 to 19.7, p=0.0014). In conclusion, based on comparisons with optical coherence tomographic findings, 64-slice MSCT may have the potential to detect vulnerable plaque. PMID:21349480

Ito, Tsuyoshi; Terashima, Mitsuyasu; Kaneda, Hideaki; Nasu, Kenya; Matsuo, Hitoshi; Ehara, Mariko; Kinoshita, Yoshihisa; Kimura, Masashi; Tanaka, Nobuyoshi; Habara, Maoto; Katoh, Osamu; Suzuki, Takahiko

2011-02-23

289

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

International Nuclear Information System (INIS)

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

2011-02-21

290

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

Science.gov (United States)

Optical coherence tomography (OCT) is a promising new technique for characterizing the structural changes of articular cartilage in osteoarthritis (OA). The calculation of quantitative parameters from the OCT signal is an important step to develop OCT as an effective diagnostic technique. In this study, two novel parameters for the quantification of optical surface reflection and surface roughness from OCT measurements are introduced: optical surface reflection coefficient (ORC), describing the amount of a ratio of the optical reflection from cartilage surface with respect to that from a reference material, and OCT roughness index (ORI) indicating the smoothness of the cartilage surface. The sensitivity of ORC and ORI to detect changes in bovine articular cartilage samples after enzymatic degradations of collagen and proteoglycans using collagenase and trypsin enzymes, respectively, was tested in vitro. A significant decrease (p ORC as well as a significant increase (p ORC or ORI were observed. To conclude, the new parameters introduced were demonstrated to be feasible and sensitive to detect typical OA-like degenerative changes in the collagen network. From the clinical point of view, the quantification of OCT measurements is of great interest since OCT probes have been already miniaturized and applied in patient studies during arthroscopy or open knee surgery in vivo. Further studies are still necessary to demonstrate the clinical capability of the introduced parameters for naturally occurring early OA changes in the cartilage.

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

2009-11-01

291

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-11-21

292

Consensus standards for acquisition, measurement, and reporting of intravascular optical coherence tomography studies : a report from the international working group for intravascular optical coherence tomography standardization and validation  

DEFF Research Database (Denmark)

The purpose of this document is to make the output of the International Working Group for Intravascular Optical Coherence Tomography (IWG-IVOCT) Standardization and Validation available to medical and scientific communities, through a peer-reviewed publication, in the interest of improving the diagnosis and treatment of patients with atherosclerosis, including coronary artery disease.

Tearney, Guillermo J; Regar, Evelyn

2012-01-01

293

Evaluation of caries-affected dentin with optical coherence tomography.  

UK PubMed Central (United Kingdom)

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.

Azevedo CS; Trung LC; Simionato MR; Freitas AZ; Matos AB

2011-09-01

294

Evaluation of caries-affected dentin with optical coherence tomography.  

Science.gov (United States)

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. PMID:22031053

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

295

Optical coherence tomography findings in spinocerebellar ataxia-3.  

UK PubMed Central (United Kingdom)

PurposeTo report optical coherence tomography (OCT) findings in order to detect subclinical alterations of the afferent visual pathways in spinocerebellar ataxia 3 (SCA-3).Patients and methodsNine genetically confirmed patients (18 eyes) were evaluated with a complete ophthalmologic examination including visual acuity, colour vision, visual field test, and retinal nerve fibre layer (RNFL) and macular thickness with OCT Cirrus HD. A neurological examination was performed and the Scale for the Assessment and Rating of Ataxia (SARA score) was determined in all patients.ResultsThe mean RNFL thickness was 77.39 microns, standard deviation (SD) was ±5.93. In 15 eyes (83.33%), the mean RNFL thickness was lower than the population average considering age and sex. In 10 cases, there was a reduction of the RNFL thickness in the superior sector, eight in the inferior and four in the nasal. Temporal sector RNFL thickness was preserved in all eyes. RNFL thickness was inversely correlated to SARA score (r=-0.64, P=0.012). The mean macular thickness was 252.61 microns, SD±22.80, being inferior respecting average population in only two eyes (11.11%). In four patients, (eight eyes) OCT studies were performed during a mean follow-up of 14.25 months, and in five eyes (62.50%) there was a mild trend to a RNFL thickness decrease in this period.ConclusionA mild and progressive decrease in RNFL thickness can be observed in SCA-3 patients. A negative correlation exists between an anatomic marker (RNFL thickness) and a clinical severity scale (SARA score); thus, RNFL thickness could be considered as a promising biomarker of the disease.Eye advance online publication, 13 September 2013; doi:10.1038/eye.2013.201.

Alvarez G; Rey A; Sanchez-Dalmau FB; Muñoz E; Ríos J; Adán A

2013-09-01

296

Anterior chamber cell grading by optical coherence tomography.  

UK PubMed Central (United Kingdom)

PURPOSE: To quantify cells in the ocular anterior chamber (AC) by optical coherence tomography (OCT). METHODS: A time-domain anterior segment OCT system was used to image latex microsphere suspensions in vitro and the AC of uveitis and normal subjects in vivo. The OCT scan pattern, consisting of 2- and 4-mm-diameter concentric circular scans, was divided into central, superior, and inferior regions. A computer algorithm was developed to automatically identify particles in OCT images. A uveitis specialist used slit-lamp biomicroscopy to grade the AC cells on a scale of 0 to 4+. RESULTS: Latex microspheres and ac cells were visualized as reflective spots in oct images. OCT latex microsphere concentration measurements were highly correlated to known particle concentrations (r = 1.000) and had an efficiency of 0.72. in 30 nongranulomatous and 12 granulomatous eyes, the OCT cell counts correlated well with slit-lamp grades in all three regions (Spearman's rho coefficient: >0.63). The average OCT cell count was 3.7 cells/grade in nongranulomatous eyes and 2.0 cells/grade in granulomatous eyes. OCT revealed significant amounts of inferior AC cells in 5 of 16 quiescent uveitis eyes (mean ± SD: 19.9 ± 7.4 cells). OCT captured rare cells in normal eyes (1.1 ± 1.1 cells centrally). CONCLUSIONS: OCT provided quantitative information on AC inflammatory cells. The OCT cell counts correlated well with clinical grading, and particles in the inferior AC that were missed by slit-lamp examination were detected by OCT. OCT could be a valuable tool for the diagnosis and management of anterior uveitis.

Li Y; Lowder C; Zhang X; Huang D

2013-01-01

297

Optical coherence tomography using the Niris system in otolaryngology  

Science.gov (United States)

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

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

2009-02-01

298

Validation of optical coherence tomography in vivo using cryostat histology  

Energy Technology Data Exchange (ETDEWEB)

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 embedding. (note)

Gambichler, T [Department of Dermatology, Ruhr-University Bochum, Gudrunstr. 56, 44791 Bochum (Germany); Moussa, G [Department of Dermatology, Ruhr-University Bochum, Gudrunstr. 56, 44791 Bochum (Germany); Regeniter, P [Department of Dermatology, Ruhr-University Bochum, Gudrunstr. 56, 44791 Bochum (Germany); Kasseck, C [Ruhr Center of Excellence for Medical Engineering (KMR) Bochum (Germany); Hofmann, M R [Ruhr Center of Excellence for Medical Engineering (KMR) Bochum (Germany); Bechara, F G [Department of Dermatology, Ruhr-University Bochum, Gudrunstr. 56, 44791 Bochum (Germany); Sand, M [Department of Dermatology, Ruhr-University Bochum, Gudrunstr. 56, 44791 Bochum (Germany); Altmeyer, P [Department of Dermatology, Ruhr-University Bochum, Gudrunstr. 56, 44791 Bochum (Germany); Hoffmann, K [Department of Dermatology, Ruhr-University Bochum, Gudrunstr. 56, 44791 Bochum (Germany)

2007-03-07

299

Statistical analysis of high density diffuse optical tomography.  

UK PubMed Central (United Kingdom)

High density diffuse optical tomography (HD-DOT) is a noninvasive neuroimaging modality with moderate spatial resolution and localization accuracy. Due to portability and wear-ability advantages, HD-DOT has the potential to be used in populations that are not amenable to functional magnetic resonance imaging (fMRI), such as hospitalized patients and young children. However, whereas the use of event-related stimuli designs, general linear model (GLM) analysis, and imaging statistics are standardized and routine with fMRI, such tools are not yet common practice in HD-DOT. In this paper we adapt and optimize fundamental elements of fMRI analysis for application to HD-DOT. We show the use of event-related protocols and GLM de-convolution analysis in un-mixing multi-stimuli event-related HD-DOT data. Statistical parametric mapping (SPM) in the framework of a general linear model is developed considering the temporal and spatial characteristics of HD-DOT data. The statistical analysis utilizes a random field noise model that incorporates estimates of the local temporal and spatial correlations of the GLM residuals. The multiple-comparison problem is addressed using a cluster analysis based on non-stationary Gaussian random field theory. These analysis tools provide access to a wide range of experimental designs necessary for the study of the complex brain functions. In addition, they provide a foundation for understanding and interpreting HD-DOT results with quantitative estimates for the statistical significance of detected activation foci.

Hassanpour MS; White BR; Eggebrecht AT; Ferradal SL; Snyder AZ; Culver JP

2013-05-01

300

Optical coherence tomography: from research to clinical application.  

Science.gov (United States)

Optical coherence tomography (OCT) has revolutionized intracoronary imaging. The unprecedented spatial resolution of this technique (15 ?m) provides unique insights on the microstructure of the coronary wall. Currently, OCT is increasingly used in clinical practice and also constitutes an emerging, highly robust, research tool. OCT allows detailed visualization of atherosclerotic plaques and provides reliable information on plaque composition (lipid, fibrous, calcified) although its limited tissue penetration usually precludes a comprehensive analysis of the total plaque burden. OCT is the only technique allowing accurate measurements of the thickness of the fibrous cap, a classical marker of plaque vulnerability, and readily detects thin-cap fibroatheromas. In patients with acute coronary syndromes, plaque ruptures, with associated red or white thrombus, are nicely identified. OCT is also valuable to assess the results of coronary interventions. Stent expansion can be easily ascertained. In addition, due to its 10-times higher resolution, OCT is superior to intravascular ultrasound in the detection of even minor degrees of strut malapposition, tissue prolapse, residual thrombus and edge dissections. Furthermore, during follow-up OCT has a unique value to unravel the presence of strut coverage and to detect mild amounts of neointimal proliferation that might represent a valid surrogate marker of drug-eluting stent safety and efficacy. Finally, OCT has been used to unravel the underlying mechanisms implicated in stent failure, namely in-stent restenosis and stent thrombosis. Therefore, OCT appears ideally suited to help to move forward our understanding on the pathophysiology of coronary artery disease and to improve clinical decision-making processes, meeting the ever-increasing demand on coronary artery anatomical information from clinicians and researchers. PMID:23229366

Alfonso, F; Sandoval, J; Cárdenas, A; Medina, M; Cuevas, C; Gonzalo, N

2012-12-01

 
 
 
 
301

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; Luciana Cardoso Espejo Trung; Maria Regina Lorenzetti Simionato; Anderson Zanardi de Freitas; Adriana Bona Matos

2011-01-01

302

Evaluation of caries-affected dentin with optical coherence tomography  

Scientific Electronic Library Online (English)

Full Text Available 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 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 microbiologi (more) cal 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.

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

2011-10-01

303

Neural networks to identify multiple sclerosis with optical coherence tomography.  

UK PubMed Central (United Kingdom)

Purpose:  To compare axonal loss in ganglion cells detected with spectral-domain optical coherence tomography (OCT) in eyes of patients with multiple sclerosis (MS) versus healthy control subjects using an artificial neural network (ANN). To analyse the capability of the ANN technique to improve the detection of retinal nerve fibre layer (RNFL) damage in patients with multiple sclerosis. Methods:  Patients with multiple sclerosis (n?=?106) and age-matched healthy subjects (n?=?115) were enrolled. The Spectralis OCT system was used to obtain the circumpapillary RNFL thickness in both eyes. The 768 RNFL thickness measurements provided by the Spectralis OCT were performed to obtain thickness measurements from 24 uniformly divided locations around the peripapillary RNFL. The performance of the ANN technique for identifying RNFL loss in patients with multiple sclerosis was evaluated. Receiver-operating characteristic (ROC) curves were used to display the ability of the test to discriminate between MS and healthy eyes in our population. ROC curves obtained using ANN and parameters provided by OCT (mean and 6 sector thicknesses) were compared. Results:  The capability of the ANN technique to detect RNFL loss in patients with multiple sclerosis compared with healthy subjects was good. The area under the ROC curve was 0.945. Compared with the OCT-provided parameters, the ANN had the largest area under the ROC curve. Conclusions:  Measurements of RNFL thickness obtained with Spectralis OCT have a good ability to differentiate between healthy and individuals with multiple sclerosis. Based on the area under the ROC curve, the ANN performed better than any single OCT parameter.

Garcia-Martin E; Pablo LE; Herrero R; Ara JR; Martin J; Larrosa JM; Polo V; Garcia-Feijoo J; Fernandez J

2013-05-01

304

Frequency domain optical coherence tomography for guidance of coronary stenting.  

UK PubMed Central (United Kingdom)

OBJECTIVE: To evaluate the role of Frequency domain optical coherence tomography (FD-OCT) in guiding stent implantation procedures. METHODS: Dragonfly-imaging catheter was used pre-intervention, after pre-dilatation or at various stages of stent deployment/post-dilatation to assess lesion severity, characteristics and guide stent expansion/apposition. RESULTS: We performed 398 OCT pull-backs in 108 consecutive patients. The 371 pull-backs analysable, had an average length of 35 mm and encompassed 193 lesions (1.8 lesions per patient). Seventy-six percent of patient had AHA-ACC-class B-C lesions. In the pre-intervention group deferral of treatment was decided for 13/68 pullbacks (19.1%), whereas strategies different from conventional predilatation (e.g. thrombectomy, rotablator, cutting-balloon) were decided in 23 cases (33.8%). After full lesion dilatation 96 pullbacks (25.9%, pre-stenting group) were performed, 46 (47.9%) of which suggested proceeding directly with stenting while 50 (52.1%) suggesting further treatment. Out of the 207 pullbacks in post-stenting group, 29 (14%) suggested new stent implantation because of dissection or residual stenosis; 64 (30.9%) suggested further optimization with high pressure/larger-sized balloon. Average number of pull-backs per patient was 3.4 requiring 75.8 ± 19.3 ml of iopamidol. No major complications were observed. Five cases (4.6%) of contrast-induced nephropathy were reported. CONCLUSIONS: Repeated examinations with FD-OCT can be safely used to guide stent selection and improve stent expansion and apposition.

Viceconte N; Chan PH; Barrero EA; Ghilencea L; Lindsay A; Foin N; Di Mario C

2013-07-01

305

Optical coherence tomography study of experimental anterior ischemic optic neuropathy and histologic confirmation.  

UK PubMed Central (United Kingdom)

PURPOSE: The optic nerve is part of the central nervous system, and interruption of this pathway due to ischemia typically results in optic atrophy and loss of retinal ganglion cells. In this study, we assessed in vivo retinal changes following murine anterior ischemic optic neuropathy (AION) by using spectral-domain optical coherence tomography (SD-OCT) and compared these anatomic measurements to that of histology. METHODS: We induced ischemia at the optic disc via laser-activated photochemical thrombosis, performed serial SD-OCT and manual segmentation of the retinal layers to measure the ganglion cell complex (GCC) and total retinal thickness, and correlated these measurements with that of histology. RESULTS: There was impaired perfusion and leakage at the optic disc on fluorescein angiography immediately after AION and severe swelling and distortion of the peripapillary retina on day-1. We used SD-OCT to quantify the changes in retinal thickness following experimental AION, which revealed significant thickening of the GCC on day-1 after ischemia followed by gradual thinning that plateaued by week-3. Thickness of the peripapillary sensory retina was also increased on day-1 and thinned chronically. This pattern of acute retinal swelling and chronic thinning on SD-OCT correlated well with changes seen in histology and corresponded to loss of retinal ganglion layer cells after ischemia. CONCLUSIONS: This was a serial SD-OCT quantification of acute and chronic changes following experimental AION, which revealed changes in the GCC similar to that of human AION, but over a time frame of weeks rather than months.

Ho JK; Stanford MP; Shariati MA; Dalal R; Liao YJ

2013-09-01

306

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

Energy Technology Data Exchange (ETDEWEB)

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.

Shin, Yongjin; Kim, Hyunjin; Kim, Youngseop; Park, Sohee [Chosun University, Gwangju (Korea, Republic of); Jung, Woonggyu; Chen, Zhongping; Nelson, J. Stuart [Beckman Laser Institute, University of California at Irvine, CA (United States)

2006-02-15

307

Power-efficient nonreciprocal interferometer and linear-scanning fiber-optic catheter for optical coherence tomography  

Energy Technology Data Exchange (ETDEWEB)

A nonreciprocal fiber-optic interferometer is demonstrated in an optical coherence tomography (OCT) system. The increased power efficiency of this system provides a 4.1-dB advantage over standard Michelson implementations. In addition, a new linear-scanning fiber-optic catheter is demonstrated that avoids the rotary optical junction that is required in circumferential scanning systems. These advancements have permitted the clinical implementation of OCT imaging in the human gastrointestinal tract. {copyright} {ital 1999} {ital Optical Society of America}

Bouma, B.E.; Tearney, G.J. [Harvard Medical School and Wellman Laboratories of Photomedicine, Massachusetts General Hospital, Boston, Massachusetts 02114 (United States)

1999-04-01

308

Real-time high-speed volumetric imaging using compressive sampling optical coherence tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Volumetric imaging of the Optic Nerve Head (ONH) morphometry with Optical Coherence Tomography (OCT) requires dense sampling and relatively long acquisition times. Compressive Sampling (CS) is an emerging technique to reduce volume acquisition time with minimal image degradation by sparsely sampling...

Young, Mei; Lebed, Evgeniy; Jian, Yifan; Mackenzie, Paul J.; Beg, Mirza Faisal; Sarunic, Marinko V.

309

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)

2008-07-31

310

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

Optical coherence tomography (OCT) has recently been used to produce 3D angiography of microvasculature and blood flow maps of large vessels in the rodent brain in-vivo. However, use of this optical method for the study of cerebrovascular disease has not been fully explored. Recent developments in n...

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

311

Feasibility study on bonding quality inspection of microfluidic devices by optical coherence tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper reports the feasibility of optical coherence tomography (OCT) technology for inspection of bonding quality of microfluidic devices in manufacturing environments. A compact optical-fiber–based OCT is developed and its measurement performance is characterized. A series of microfluidic devic...

Li, Shiguang; Xu, Zhiguang; Yoon, Soon Fatt; Fang, Zhong Ping

312

Spectral domain optical coherence tomography: ultra-high speed, ultra-high resolution ophthalmic imaging.  

UK PubMed Central (United Kingdom)

OBJECTIVE: To introduce a new ophthalmic optical coherence tomography technology that allows unprecedented simultaneous ultra-high speed and ultra-high resolution. METHODS: Using a superluminescent diode source, a clinically viable ultra-high speed, ultra-high resolution spectral domain optical coherence tomography system was developed. RESULTS: In vivo images of the retina, the optic nerve head, and retinal blood flow were obtained at an ultra-high speed of 34.1 microseconds (ms) per A-scan, which is 73 times faster than commercially available optical coherence tomography instruments. Single images (B-scans) consisting of 1000 A-scans were acquired in 34.1 ms, allowing video rate imaging at 29 frames per second with an axial resolution of 6 mum. Using a different source in a slightly slower configuration, single images consisting of 500 A-scans were acquired in 34 ms, allowing imaging at 29 frames per second at an axial resolution of 3.5 microm, which is 3 times better than commercially available optical coherence tomography instruments. The amount of energy directed into the eye in both cases, 600 microW, is less than that of the Stratus OCT3 and is safe for intrabeam viewing for up to 8 hours at the same retinal location. CONCLUSION: Spectral domain optical coherence tomography technology enables ophthalmic imaging with unprecedented simultaneous ultra-high speed and ultra-high resolution.

Chen TC; Cense B; Pierce MC; Nassif N; Park BH; Yun SH; White BR; Bouma BE; Tearney GJ; de Boer JF

2005-12-01

313

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

Energy Technology Data Exchange (ETDEWEB)

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.

Ugryumova, Nadya; Attenburrow, Don P; Winlove, C Peter; Matcher, Stephen J [Biomedical Physics Group, School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL (United Kingdom)

2005-08-07

314

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

2000-01-15

315

Topographic Optic Disc Changes After Successful Trabeculectomy Evaluated Using Spectral Domain Optical Coherence Tomography.  

UK PubMed Central (United Kingdom)

Abstract Purpose: To investigate topographic optic disc changes after surgical intraocular pressure (IOP) reduction in adults with open angle glaucoma (OAG). Methods: Optic discs of patients with advanced primary open angle or exfoliation glaucoma were imaged using optical coherence tomography within 1 week before trabeculectomy. Patients were rescanned 1 week, 1 month, and 1 year after surgery. Maximum cup depth (MCD), and average cup depth (ACD) were calculated. Results: Twenty-two eyes from 20 patients (age, 70.5±10.6 years; average mean defect of visual field, -15.0±9.8?dB) were followed up for 1 year. The IOP decreased from 22.1±2.8?mmHg at baseline to 11.5±2.6?mmHg 1 year following surgery (P<0.001). One-week and 1-month postoperative IOPs were 11.2±2.8 and 11.2±3.5?mmHg, respectively (P<0.001). Compared to the baseline values (356±172??m), postoperative ACD showed a significant decrease at 1 week (312±164??m; P<0.001) and 1 month (338±175??m; P=0.007) after surgery, but not at 1 year (339±176??m; P=0.354). Similarly, MCD significantly decreased from baseline (477±190??m) 1 week (431±203??m; P=0.029) and 1 month (448±198??m; P=0.047) after the surgery, but not after 1 year (479±188??m; P=1.0). Conclusions: Trabeculectomy reduces IOP in eyes with advanced OAG, which induces topographic optic disc changes. Such optic disc changes became less pronounced over time and were no longer detectable 1 year after surgery.

Russo A; Katsanos A; Riva I; Floriani I; Biagioli E; Quaranta L

2013-09-01

316

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

317

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

2005-01-01

318

Multiple-depth en face optical coherence tomography using active recirculation loops.  

UK PubMed Central (United Kingdom)

We present a novel low-coherence interferometer configuration, equipped in each arm with an adjustable optical path length ring. By compensating for the losses in the rings using semiconductor optical amplifiers, interference of low-coherence light after traversing the two rings 18 times is obtained. This configuration is employed to demonstrate simultaneous en face optical coherence tomography imaging at five different depths in a Drosophila melanogaster fly.

Neagu L; Bradu A; Ma L; Bloor JW; Podoleanu AG

2010-07-01

319

Hand-held spectral domain optical coherence tomography finding in shaken-baby syndrome.  

UK PubMed Central (United Kingdom)

PURPOSE: The purpose of this study was to document the hand-held spectral domain optical coherence tomography (HHSD-OCT, Bioptigen, Durham, NC) findings in shaken-baby syndrome (SBS). The nonaccidental trauma in SBS has been associated with retinal findings, including hemorrhages in all layers of the retina and retinoschisis. METHODS: Three consecutive patients with presumed SBS underwent complete ocular examination, fundus photography with the RetCam (Clarity Medical Systems, Pleasanton, CA), and imaging with the HHSD-OCT. Acquisition of the HHSD-OCT images required an assistant to stabilize the head of the infant. RESULTS: All three patients had clinical findings consistent with SBS, including preretinal and intraretinal hemorrhages. Hand-held spectral domain optical coherence tomography documented focal posterior vitreous separation in four of the five eyes with multilayered retinoschisis in one eye, disruption of the foveal architecture and foveolar detachment in one eye, and disinsertion of the internal limiting membrane or inner retinoschisis in one eye. Hand-held spectral domain optical coherence tomography documented preretinal hemorrhages in all five eyes. CONCLUSION: Hand-held spectral domain optical coherence tomography is helpful in the evaluation of patients with SBS. All patients in our series had vitreoretinal abnormalities not detected on clinical examination, including, for example, multilayered retinoschisis. Hand-held spectral domain optical coherence tomography allows high-resolution imaging of the vitreoretinal interface and retina in infants with SBS and has provided insight into the mechanism of various retinal findings.

Muni RH; Kohly RP; Sohn EH; Lee TC

2010-04-01

320

Inflammatory markers and plaque morphology: an optical coherence tomography study.  

UK PubMed Central (United Kingdom)

BACKGROUND: OCT with its unique image resolution is the ideal method to detect culprit lesion characteristics in different clinical presentations. The identification of inflammatory markers related to plaque characteristics may be of clinical importance. METHODS: Thirty-two patients with acute coronary syndromes (ACS) and fourteen patients with stable angina pectoris (SAP) were enrolled in this study. Culprit lesion morphology was assessed by optical coherence tomography (OCT) in patients with ACS and SAP. The possible relations between serum levels of high sensitivity-C reactive protein (hs-CRP) and interleukin-18 (IL-18) with plaque characteristics were investigated in those patients. RESULTS: Plaque rupture and thin-cap fibroatheroma (TCFA) were detected more frequently in ACS patients compared with SAP patients, (78.6% vs. 14.3%, p<0.001, 92.9% vs. 14.3%, p<0.001, respectively). Higher levels of serum hs-CRP and IL-18 were found in patients with plaque rupture vs. those with no plaque rupture (median value: 19.2mg/L vs. 1.6 mg/L, p<0.001 and 219.5 pg/ml vs. 127.5 pg/ml, p=0.001 respectively), and TCFA vs. those without TCFA (median value: 15.2mg/L vs. 1.6 mg/L, p=0.004 and 209.0 pg/ml vs.153.2 pg/ml, p=0.03 respectively). Serum hs-CRP was the only independent predictor of plaque rupture (p=0.02, odds ratio 1.1, 95% confidence interval 1.0 to 1.2). A cut-off value of hs-CRP>4.5mg/L could detect ruptured plaque with a sensitivity of 91.7% and a specificity of 77.8%. CONCLUSIONS: OCT detected plaque rupture and TCFA more frequent in ACS patients compared with SAP. Elevated hs-CRP and IL-18 were positively related to plaque instability and rupture.

Bouki KP; Katsafados MG; Chatzopoulos DN; Psychari SN; Toutouzas KP; Charalampopoulos AF; Sakkali EN; Koudouri AA; Liakos GK; Apostolou TS

2012-02-01

 
 
 
 
321

Automated characterization of pigment epithelial detachment by optical coherence tomography.  

UK PubMed Central (United Kingdom)

PURPOSE: To assess the accuracy of automated classification of pigment epithelial detachments (PED) by using a software algorithm applied to spectral-domain optical coherence tomography (SD-OCT) scans. METHODS: HD-OCT (Cirrus; Carl Zeiss Meditec, Dublin, CA) volume scans (512 × 128) were retrospectively collected from 46 eyes of 33 patients with evidence of PED in the setting of age-related macular degeneration (AMD, n = 28) or central serous chorioretinopathy (CSCR, n = 5). In these eyes, 168 PEDs were automatically detected with a system-associated tool (Cirrus HD-OCT RPE Elevation Analysis; Carl Zeiss Meditec). Two independent, certified Doheny Image Reading Center (DIRC) OCT graders classified these PEDs into three categories--serous, drusenoid, or fibrovascular--via inspection of the B-scans. Manual classification results served as the gold standard for comparisons with automated classification. For automated classification, interindividual variation in intensities was normalized in all images. Individual A-scans within the detected PEDs were then automatically classified into one of three categories based on the mean internal intensity and the standard deviation of the internal intensity: mean intensity <30 (serous type); mean intensity ?30 but <60 or mean intensity ?30 and SD ?30 (fibrovascular type); or mean intensity ?60 and SD < 30 (drusenoid type). Individual PEDs were then automatically classified into the same three categories based on the predominant type of A-scan within the PED. For mixed PEDs (many A-scans of each type), a risk index for neovascularization was computed based on the percentage of fibrovascular A-scans. In addition, a confidence index was computed for each PED based on its mathematical distance from the PED category boundaries. RESULTS: Among the 168 PEDs, the DIRC graders classified 16 as serous, 88 as fibrovascular, and 64 as drusenoid PEDs. The automated algorithm classified 14 as serous, 96 as fibrovascular, and 58 as drusenoid PEDs. The sensitivity and specificity values for automated classification according to type of PED were 88% and 100% for serous, 76% and 64% for fibrovascular, and 58% and 81% for drusenoid, respectively. CONCLUSIONS: Automated classification of PEDs using internal reflectivity characteristics appears to be sensitive for detecting serous and fibrovascular PEDs. Automated classification and quantification of PEDs may be a useful tool in future studies for stratifying PEDs according to risk and possibly predicting the risk of advanced AMD.

Lee SY; Stetson PF; Ruiz-Garcia H; Heussen FM; Sadda SR

2012-01-01

322

Characteristics of peripapillary choroidal cavitation detected by optical coherence tomography.  

UK PubMed Central (United Kingdom)

PURPOSE: To evaluate the clinical features of peripapillary choroidal cavitation (PCC) detected by optical coherence tomography (OCT). DESIGN: Retrospective, observational case series. PARTICIPANTS: One hundred twenty-two eyes from 83 patients diagnosed with PCC by OCT database review were included in this study. METHODS: Stereoscopic color fundus photographs from eyes with PCC were reviewed by 2 independent ophthalmologists. They were masked to the refractive error, axial length, and OCT findings. MAIN OUTCOME MEASURES: Chart review and data analysis included gender, age, best-corrected visual acuity (BCVA), refractive error, axial length, clinical appearance of the peripapillary area, and associated funduscopic abnormalities. RESULTS: One hundred twenty-two eyes with PCC from 83 patients were analyzed. Among the patients, 41.8% were men and 58.2% were women. The mean age was 48.2 ± 12.6 years and mean BCVA in logarithm of the minimum angle of resolution units was 0.23 ± 0.43. The mean refractive error in spherical equivalent was -9.03 ± 5.11 diopters (D) and mean axial length (AL) was 27.36 ± 2.09 mm. With respect to refractive error, 90 eyes (73.8%) were highly myopic (?-6.00 D), 24 eyes (19.7%) had low myopia (<-6.00 D), 5 eyes (4.1%) were emmetropic (1.00 to -1.00 D), and 3 eyes (2.6%) were hyperopic (>1.00 D). Forty eyes (32.8%) with PCC had AL of less than 26.50 mm (mean, 25.11 ± 1.07 mm; range, 22.51-26.42 mm). Patients with eyes with PCC that had low myopia, were emmetropic, and were hyperopic also were significantly older than patients with highly myopic eyes (P<0.05). Stereoscopic fundus photographs demonstrated a yellow-orange, localized, well-circumscribed peripapillary lesion in 57 (46.7%) eyes with PCC. A PCC with opening was observed in 14 (26.4%) of 53 eyes with excavated myopic conus and in 5 (7.2%) of 69 eyes without excavated myopic conus (P<0.05). CONCLUSIONS: This study demonstrated that peripapillary choroidal cavitation is common and not exclusive to highly myopic eyes. The funduscopic finding of a yellow-orange peripapillary abnormality may not be evident in all eyes with demonstrable PCC by OCT. Although its pathogenesis and pathologic significance require further investigation, PCC may be a degenerative change in aging eyes.

Yeh SI; Chang WC; Wu CH; Lan YW; Hsieh JW; Tsai S; Chen LJ

2013-03-01

323

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

Directory of Open Access Journals (Sweden)

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

Atsushi Miki; Motohiro Shirakashi; Kiyoshi Yaoeda; et al

2010-01-01

324

Anterior segment optical coherence tomography in the assessment of postoperative intraocular lens optic changes.  

UK PubMed Central (United Kingdom)

PURPOSE: To evaluate the use of anterior segment optical coherence tomography (AS-OCT) to assess postoperative intraocular lens (IOL) optic changes. SETTING: John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA. DESIGN: Experimental study. METHODS: Intraocular lenses explanted because of various complications were used, including poly(methyl methacrylate) (PMMA) IOLs with snowflake degeneration, hydrophilic acrylic IOLs with calcification, a silicone IOL with calcification from an eye with asteroid hyalosis, and hydrophobic acrylic IOLs explanted because of decentration, subluxation, or uveitis-glaucoma-hyphema syndrome. After gross and light microscopy, the IOLs were examined in the dry and hydrated states using AS-OCT. Selected hydrophilic acrylic IOLs were stained for calcium. In-the-bag IOLs in pseudophakic cadaver eyes were also evaluated by AS-OCT before and after explantation to confirm correspondence with the clinical situation. RESULTS: Intraoptic changes, such as snowflake lesions in PMMA IOLs, calcification in hydrophilic acrylic IOLs, and glistenings in hydrophobic acrylic IOLs, could be imaged by AS-OCT. The method was also helpful in analyzing the location and density. However, in cases of more superficial changes, unless the lesions/deposits were present on the optic surface with an extension to the optic substance of at least 0.1 mm, they could not be clearly differentiated from the overall outline of the IOL surface. CONCLUSIONS: Anterior segment OCT may be helpful in assessing the presence, location, and density of intraoptic changes, avoiding a misdiagnosis of IOL opacification and the performance of unnecessary procedures, such as posterior capsulotomy or vitrectomy.

Werner L; Michelson J; Ollerton A; Leishman L; Bodnar Z

2012-06-01

325

[Dome-shaped macula: Appearance on ultrasound and optical coherence tomography.  

Science.gov (United States)

INTRODUCTION: The purpose of our work is to demonstrate the role of optical coherence tomography and ocular ultrasound in the diagnosis of the dome-shaped macula in high myopia. OBSERVATION: We report the case of a patient with high myopia who presented with a decrease in visual acuity and metamorphopsia in the left eye. She underwent visual acuity measurement, biomicroscopic examination and measurement of axial length. B-mode ultrasound and optical coherence tomography showed a projection of the macula in the convexity of the myopic staphyloma confirming the diagnosis of dome-shaped macula. DISCUSSION AND CONCLUSION: Dome-shaped macula is a recently discovered entity, which may be responsible for a decrease in visual acuity in patients with high myopic posterior staphyloma. Ultrasound and optical coherence tomography are very helpful in making the diagnosis. PMID:23706607

Chéour, M; Ben Aleya, N; Brour, J; Falfoul, Y; Agrebi, S; Skhiri, M; Kraïem, A

2013-05-22

326

{ital In vivo} bidirectional color Doppler flow imaging of picoliter blood volumes using optical coherence tomography  

Energy Technology Data Exchange (ETDEWEB)

We describe a novel optical system for bidirectional color Doppler imaging of flow in biological tissues with micrometer-scale resolution and demonstrate its use for {ital in vivo} imaging of blood flow in an animal model. Our technique, color Doppler optical coherence tomography (CDOCT), performs spatially localized optical Doppler velocimetry by use of scanning low-coherence interferometry. CDOCT is an extension of optical coherence tomography (OCT), employing coherent signal-acquisition electronics and joint time-frequency analysis algorithms to perform flow imaging simultaneous with conventional OCT imaging. Cross-sectional maps of blood flow velocity with {lt}50{minus}{mu}m spatial resolution and {lt}0.6{minus}mm/s velocity precision were obtained through intact skin in living hamster subdermal tissue. This technology has several potential medical applications. {copyright} {ital 1997} {ital Optical Society of America}

Izatt, J.A.; Kulkarni, M.D.; Yazdanfar, S. [Departments of Biomedical Engineering and Medicine, Case Western Reserve University, Cleveland, Ohio 44106 (United States); Barton, J.K.; Welch, A.J. [Biomedical Engineering Program, University of Texas at Austin, Austin, Texas 78712 (United States)

1997-09-01

327

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

Directory of Open Access Journals (Sweden)

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

Mário L. R. Monteiro; Allan C. P. Gonçalves; Carla T. M. Silva; Janete P. Moura; Carolina S. Ribeiro; Eloisa M.M.S. Gebrim

2008-01-01

328

Enhanced depth imaging optical coherence tomography of deep optic nerve complex structures in glaucoma.  

UK PubMed Central (United Kingdom)

OBJECTIVE: To assess the usefulness of enhanced depth imaging (EDI) optical coherence tomography (OCT) for evaluating deep structures of the optic nerve complex (ONC; optic nerve head and peripapillary structures) in glaucoma. DESIGN: Prospective, observational study. PARTICIPANTS: Seventy-three established glaucoma patients (139 eyes) with a range of glaucomatous damage. METHODS: Serial horizontal and vertical EDI OCT images of the ONC were obtained from both eyes of each participant. Deep ONC structures, including the lamina cribrosa (LC), short posterior ciliary artery (SPCA), central retinal artery (CRA), central retinal vein (CRV), peripapillary choroid and sclera, and subarachnoid space around the optic nerve, were investigated for their visibility and morphologic features. MAIN OUTCOME MEASURES: Deep ONC structures identified in EDI OCT images. RESULTS: Visual field mean deviation of 139 included eyes was -11.8 ± 8.6 dB (range, -28.70 to -2.01 dB). The anterior laminar surface was identified in all eyes in the central laminar area and in 91 (65%) eyes in the periphery beneath the neuroretinal and scleral rims or vascular structures. The LC pores with various shapes and sizes were visualized in 106 (76%) eyes, mainly in the central and temporal areas of the LC. Localized LC lesions seen on optic disc photographs were identified as focal LC defects (partial loss of LC tissue) in the EDI OCT images. The locations of the CRA and CRV were identified in all eyes. In the LC, the CRA maintained a straight shape with a consistent caliber, but the CRV (and tributaries) assumed a more irregular shape. The SPCAs, their branches through the emissary canals in the sclera, or both were visualized in 120 (86%) eyes. The subarachnoid space around the optic nerve was identified with varying degrees of clarity in 25 eyes (18%): 17 had high myopia and extensive parapapillary atrophy. Intrachoroidal cavitation or choroidal schisis, which had been unrecognized clinically, was identified in 2 eyes (1%) with high myopia. CONCLUSIONS: Enhanced depth imaging OCT was able to visualize a wide variety of deep ONC structures in glaucoma patients and may be helpful in detecting, conceptualizing, and understanding basic and complicated in vivo anatomic and pathologic features of the ONC in glaucoma. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found after the references.

Park SC; De Moraes CG; Teng CC; Tello C; Liebmann JM; Ritch R

2012-01-01

329

Comparison of in vivo assessment of vulnerable plaque by 64-slice multislice computed tomography versus optical coherence tomography.  

UK PubMed Central (United Kingdom)

The aim of this study was to investigate the possibility of 64-slice multislice computed tomography (MSCT) to detect vulnerable plaque derived by optical coherence tomography. From September 2007 through December 2009, 122 lesions in 81 patients were evaluated by 64-slice MSCT and optical coherence tomography. Based on optical coherence tomographic findings, lesions were classified as thin-capped fibroatheroma (TCFA; n=37) and non-TCFA (n=85). Mean computed tomographic density value of the lesion was lower and remodeling index was larger in the TCFA group (44.9 ± 19.2 vs 78.7 ± 25.0 HU, p <0.0001; 1.14 ± 0.20 vs 0.95 ± 0.16, p<0.0001, respectively). Mean computed tomographic density value was correlated and remodeling index was inversely correlated with fibrous cap thickness (r=0.605, p<0.0001; r=-0.591, p<0.0001, respectively). Optimal threshold of mean computed tomographic value and remodeling index identified by receiver operating characteristic curve were 62.4 HU and 1.08 (area under the curve 0.859 and 0.781). Signet ringlike appearance was observed more frequently in the TCFA group (65% vs 16%, p<0.0001). In multivariate analysis, independent predictors of TCFA were mean computed tomographic density value ?62.4 HU (odds ratio 8.20, 95% confidential interval 2.49 to 27.0, p=0.0005), remodeling index ?1.08 (odds ratio 6.10, 95% confidential interval 2.04 to 18.2, p=0.0012), and signet ringlike appearance (odds ratio 6.33, 95% confidential interval 2.03 to 19.7, p=0.0014). In conclusion, based on comparisons with optical coherence tomographic findings, 64-slice MSCT may have the potential to detect vulnerable plaque.

Ito T; Terashima M; Kaneda H; Nasu K; Matsuo H; Ehara M; Kinoshita Y; Kimura M; Tanaka N; Habara M; Katoh O; Suzuki T

2011-05-01

330

Complete complex conjugate resolved heterodyne swept-source optical coherence tomography using a dispersive optical delay line  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Swept-source optical coherence tomography (SSOCT) provides a substantial sensitivity advantage over its time-domain counterpart, but suffers from a reduced imaging depth range due to sensitivity falloff and complex conjugate ambiguity. Heterodyne complex conjugate-resolved SSOCT (HCCR-SSOCT) has bee...

Dhalla, Al-Hafeez; Izatt, Joseph A.

331

The "pitchfork sign" a distinctive optical coherence tomography finding in inflammatory choroidal neovascularization.  

UK PubMed Central (United Kingdom)

PURPOSE: To report four examples of a novel optical coherence tomography finding, which appears to be characteristic of inflammatory choroidal neovascularization. METHODS: Retrospective observational case series. RESULTS: Four eyes of four patients were diagnosed clinically with inflammatory choroidal neovascularization and underwent optical coherence tomography. In each case, imaging revealed multiple, distinctive finger-like projections extending from the area of active choroidal neovascularization into the outer retina-the "pitchfork sign"--a finding not typically seen in Type 2 neovascularization due to other etiologies. CONCLUSION: The pitchfork sign may help distinguish inflammatory choroidal neovascularization from other causes of Type 2 neovascularization.

Hoang QV; Cunningham ET Jr; Sorenson JA; Freund KB

2013-05-01

332

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) ...

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

333

[Usefulness of optical coherence tomography in the treatment and monitoring of posterior scleritis: report of a case].  

UK PubMed Central (United Kingdom)

CASE REPORT: We describe the findings on optical coherence tomography before and after treatment with corticosteroids in a 51 year old patient with recurrent episodes of bilateral posterior scleritis without associated systemic disease. DISCUSSION: We believe that optical coherence tomography allows the pathological changes that occur in posterior scleritis to be monitored by objective and quantitative comparison of images, and even for therapeutic decisions.

Iglesias Martín J; Díaz Rodríguez E

2012-05-01

334

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

335

Feasibility study on bonding quality inspection of microfluidic devices by optical coherence tomography.  

UK PubMed Central (United Kingdom)

This paper reports the feasibility of optical coherence tomography (OCT) technology for inspection of bonding quality of microfluidic devices in manufacturing environments. A compact optical-fiber-based OCT is developed and its measurement performance is characterized. A series of microfluidic devices respectively bonded by adhesive tape, thermal method, and oxygen plasma, are inspected. The defects of geometry deformation and sealing completeness are emphasized during measurements. Based on the inspection results, some discoveries related to the production of microfluidic devices are discussed.

Li S; Xu Z; Yoon SF; Fang ZP

2011-06-01

336

Beam-deflection optical tomography of the refractive-index distribution based on the Rytov approximation.  

Science.gov (United States)

A method of beam-deflection optical tomography based on the Rytov approximation of the wave equation is proposed. A linear relation between the deflection angle and the refractive-index distribution from the Rytov approximation and an equation of geometrical optics is derived. The tomographic reconstruction in this method is reduced to the solution of a system of linear equations. Experimental results show that this method can reconstruct strongly refracting fields from projection data of six view angles. PMID:20802750

Sasaki, O; Kobayashi, T

1993-02-10

337

Beam-deflection optical tomography of the refractive-index distribution based on the Rytov approximation.  

UK PubMed Central (United Kingdom)

A method of beam-deflection optical tomography based on the Rytov approximation of the wave equation is proposed. A linear relation between the deflection angle and the refractive-index distribution from the Rytov approximation and an equation of geometrical optics is derived. The tomographic reconstruction in this method is reduced to the solution of a system of linear equations. Experimental results show that this method can reconstruct strongly refracting fields from projection data of six view angles.

Sasaki O; Kobayashi T

1993-02-01

338

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

2005-08-07

339

Design and evaluation of a miniature probe integrating diffuse optical tomography and electroencephalographic source localization.  

UK PubMed Central (United Kingdom)

We present a dual-modality three-dimensional imaging approach that integrates diffuse optical tomography (DOT) and electroencephalographic source localization (ESL). This dual-modal DOT/ESL approach is evaluated using solid tissue-like phantoms where targets having both optical and electrical contrasts relative to the background phantom are included. The results obtained from extensive phantom experiments show that this dual-modal approach is suitable for imaging seizure focus in the study of epilepsy.

Yang H; Jiang H

2013-07-01

340

Fréchet derivative with respect to the shape of a strongly convex nonscattering region in optical tomography  

Science.gov (United States)

The aim of optical tomography is to reconstruct the optical properties inside a physical body, e.g. a neonatal head, by illuminating it with near-infrared light and measuring the outward flux of photons on the object boundary. Because a brain consists of strongly scattering tissue with imbedded cavities filled by weakly scattering cerebrospinal fluid, propagation of near-infrared photons in the human head can be treated by combining the diffusion approximation of the radiative transfer equation with geometrical optics to obtain the radiosity-diffusion forward model of optical tomography. At the moment, a disadvantage with the radiosity-diffusion model is that the locations of the transparent cavities must be known in advance in order to be able to reconstruct the physiologically interesting quantities, i.e., the absorption and the scatter in the strongly scattering brain tissue. In this work we show that the boundary measurement map of optical tomography is Fréchet differentiable with respect to the shape of a strongly convex nonscattering region. Using this result, we introduce a numerical algorithm for approximating an unknown nonscattering cavity by a ball if the background diffuse optical properties of the object are known. The functionality of the method is demonstrated through two-dimensional numerical experiments.

Hyvönen, Nuutti

2007-10-01

 
 
 
 
341

Characterizing refractive index and thickness of biological tissues using combined multiphoton microscopy and optical coherence tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present a noninvasive method for characterizing the refractive index (RI) and thickness distribution in biological tissues using a combined multiphoton microscopy (MPM) and optical coherence tomography (OCT) system. Tissue layers are distinguished by the MPM and OCT images, and the RI and thickne...

Zhou, Yifeng; Chan, Kenny K. H.; Lai, Tom; Tang, Shuo

342

Enabling freehand lateral scanning of optical coherence tomography needle probes with a magnetic tracking system  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present a high-resolution three-dimensional position tracking method that allows an optical coherence tomography (OCT) needle probe to be scanned laterally by hand, providing the high degree of flexibility and freedom required in clinical usage. The method is based on a magnetic tracking system, ...

Yeo, Boon Y.; McLaughlin, Robert A.; Kirk, Rodney W.; Sampson, David D.

343

Image analysis for classification of dysplasia in Barrett’s esophagus using endoscopic optical coherence tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Barrett’s esophagus (BE) and associated adenocarcinoma have emerged as a major health care problem. Endoscopic optical coherence tomography is a microscopic sub-surface imaging technology that has been shown to differentiate tissue layers of the gastrointestinal wall and identify dysplasia in the mu...

Qi, Xin; Pan, Yinsheng; Sivak, Michael V.; Willis, Joseph E.; Isenberg, Gerard; Rollins, Andrew M.

344

Optical coherence tomography—current technology and applications in clinical and biomedical research  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Optical coherence tomography (OCT) is a noninvasive imaging technique that provides real-time two- and three-dimensional images of scattering samples with micrometer resolution. By mapping the local reflectivity, OCT visualizes the morphology of the sample. In addition, functional properties such as...

Marschall, Sebastian; Sander, Birgit; Mogensen, Mette; Jørgensen, Thomas Martini; Andersen, Peter E.

345

Optical coherence tomography for the identification of musculoskeletal structures of the spine: a pilot study  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Adolescent idiopathic scoliosis (AIS) is a complex three-dimensional deformity of the spine requiring in severe cases invasive surgery. Here, we explore the potential of optical coherence tomography (OCT) as a guiding tool for novel fusionless minimally invasive spinal surgeries on an ex vivo porcin...

Beaudette, Kathy; Strupler, Mathias; Benboujja, Fouzi; Parent, Stefan; Aubin, Carl-Eric; Boudoux, Caroline

346

How histological features of basal cell carcinomas influence image quality in optical coherence tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Optical coherence tomography (OCT) has the potential to diagnose and measure the depth of nonmelanoma skin cancer (NMSC) in skin, but some lesions appear blurred in OCT images. The aim of this study is to identify histological characteristics of basal cell carcinomas (BCC) that correlate with good q...

Mogensen, Mette; Nürnberg, Birgit M.; Thrane, Lars; Jørgensen, Thomas Martini; Andersen, Peter E.; Jemec, Gregor B. E.

347

Doppler imaging with dual-detection full-range frequency domain optical coherence tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Most of full-range techniques for Frequency Domain Optical Coherence Tomography (FD-OCT) reported to date utilize the phase relation between consecutive axial lines to reconstruct a complex interference signal and hence may exhibit degradation in either mirror image suppression performance or detect...

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

348

Swept-source based, single-shot, multi-detectable velocity range Doppler optical coherence tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Phase-Resolved Doppler Optical Coherence Tomography (PR-DOCT) allows visualization and characterization of the location, direction, velocity, and profile of flow activity embedded in a static sample structure. The detectable Velocity Dynamic Range (VDR) of each particular PR-DOCT system is governed ...

Meemon, Panomsak; Rolland, Jannick P.

349

Retinal neovascularization secondary to proliferative diabetic retinopathy characterized by spectral domain optical coherence tomography.  

UK PubMed Central (United Kingdom)

PURPOSE: The purpose of this study was to characterize diabetic retinal neovascularization (NV) and accompanying retinal and vitreal morphologic changes using high-resolution spectral domain optical coherence tomography. METHODS: A cross-sectional retrospective analysis was performed on 16 eyes of 14 nonconsecutive subjects with proliferative diabetic retinopathy that were seen between August 2011 and December 2011 at the New England Eye Center, Boston, MA. Patients who had NV of the disk, NV elsewhere, and intraretinal microvascular abnormalities were scanned using optical coherence tomography directly over the region of the abnormal vessels. RESULTS: Characteristic changes of the retinal vasculature, retina, and vitreous were seen in the 16 eyes with NV. This study describes optical coherence tomography characteristics of 1) NV of the disk, 2) NV elsewhere, 3) intraretinal microvascular abnormality, 4) NV causing traction without retinal detachment; and 5) NV causing traction with retinal detachment. The morphologic appearance of vitreous traction was found to be consistent with the previous histologic reports. CONCLUSION: It is possible to image diabetic NV using spectral domain optical coherence tomography and to visualize the spectrum of retinal, retinal vascular, and vitreal changes seen through these areas of abnormal retinal vasculature.

Cho H; Alwassia AA; Regiatieri CV; Zhang JY; Baumal C; Waheed N; Duker JS

2013-03-01

350

Signal attenuation and box-counting fractal analysis of optical coherence tomography images of arterial tissue  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The sensitivity of optical coherence tomography images to sample morphology is tested by two methods. The first method estimates the attenuation of the OCT signal from various regions of the probed tissue. The second method uses a box-counting algorithm to calculate the fractal dimensions in the reg...

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

351

Optical Coherence Tomography for the Assessment of Coronary Atherosclerosis and Vessel Response after Stent Implantation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Optical Coherence Tomography (OCT) is a light-based imaging modality that can provide in vivo high-resolution images of the coronary artery with a level of resolution (axial 10-20 µm) ten times higher than intravascular ultrasound. The technique, uses low-coherent near infrarred light to create hig...

Gonzalo, N.

352

Speckle variance optical coherence tomography of the rodent spinal cord: in vivo feasibility  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Optical coherence tomography (OCT) has the combined advantage of high temporal (µsec) and spatial (<10µm) resolution. These features make it an attractive tool to study the dynamic relationship between neural activity and the surrounding blood vessels in the spinal cord, a topic that is poorly under...

Cadotte, David W.; Mariampillai, Adrian; Cadotte, Adam; Lee, Kenneth K. C.; Kiehl, Tim-Rasmus; Wilson, Brian C.

353

Imaging of laser-photocoagulated diabetic microaneurysm with spectral domain optical coherence tomography.  

UK PubMed Central (United Kingdom)

PURPOSE: To analyze the morphology of microaneurysms before and after direct photocoagulation using spectral domain optical coherence tomography. METHODS: In 13 eyes of diabetic patients who underwent focal photocoagulation for clinically significant macular edema, microaneurysms were evaluated before, immediately after, 1 month after, and 2 months after photocoagulation with spectral domain optical coherence tomography. The microaneurysms were also evaluated by fluorescein angiography and color fundus photography. The patients underwent focal photocoagulation for microaneurysm. RESULTS: The microaneurysms before photocoagulation in spectral domain optical coherence tomography were observed as circular or elliptical structures with hyperreflective foci within vessel walls. Immediately after photocoagulation, the microaneurysms were changed to indistinct lesions with hyperreflectivity around the microaneurysms. Acoustic shadows developed on the choroidal side of the microaneurysms. If photocoagulation for microaneurysms was appropriately done, retinal changes were limited to within the inner retina around the microaneurysms and no changes were observed in retinal pigment epithelium. Within 2 months after photocoagulation, the microaneurysms changed into fine scars and the retinal structure normalized. Average retinal thickness of the fovea was 432 ± 70 ?m before the procedure but reduced to 373 ± 84 ?m at 2 months post surgery. CONCLUSION: Focal photocoagulation may be a less invasive method for treating microaneurysms, and spectral domain optical coherence tomography is useful for evaluating the efficacy of photocoagulation.

Yamada Y; Suzuma K; Fujikawa A; Kumagami T; Kitaoka T

2013-04-01

354

The effect of smoking on choroidal thickness measured by optical coherence tomography.  

UK PubMed Central (United Kingdom)

BACKGROUND/AIMS: To investigate the effect of smoking on choroidal thickness using Fourier domain optical coherence tomography. METHODS: 17 otherwise healthy smokers (study group) and 17 non-smokers (control group) were enrolled. In the study group, all participants underwent optical coherence tomography scanning at baseline, and 1 and 3 h following smoking one standard cigarette. Also the participants of the control group underwent optical coherence tomography scanning in the morning which was followed by two further examinations at the first and third hours, respectively. Choroidal thickness measurements were performed. RESULTS: The mean choroidal thickness at the fovea prior to smoking was 301.1±63.1 ?m, which decreased to 284.2±56.7 ?m at 1 h and 270.8±80.0 ?m at 3 h following smoking (p=0.001). The mean choroidal thickness was significantly decreased following smoking at all five extrafoveal points. The difference in choroidal thickness was not statistically significant at 1 and 3 h of smoking at all six points. In the control group, the mean baseline choroidal thickness at the fovea was 270.6±57.9 ?m, which was 272.5±52.4 ?m at 1 h and 273.8±57.4 ?m at 3 h (p=0.816). CONCLUSIONS: Cigarette smoking causes a significant decrease in choroidal thickness following smoking. Fourier domain optical coherence tomography can effectively demonstrate choroidal thickness.

Sizmaz S; Küçükerdönmez C; Pinarci EY; Karalezli A; Canan H; Yilmaz G

2013-05-01

355

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

Optical coherence tomography (OCT) systems are becoming more commonly used in biomedical imaging and, to enable continued uptake, a reliable method of characterizing their performance and validating their operation is required. This paper outlines the use of femtosecond laser subsurface micro-inscri...

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

356

In vivo photothermal optical coherence tomography of gold nanorod contrast agents  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Photothermal optical coherence tomography (PT-OCT) is a potentially powerful tool for molecular imaging. Here, we characterize PT-OCT imaging of gold nanorod (GNR) contrast agents in phantoms, and we apply these techniques for in vivo GNR imaging. The PT-OCT signal was compared to the bio-heat equat...

Tucker-Schwartz, J. M.; Meyer, T. A.; Patil, C. A.; Duvall, C. L.; Skala, M. C.

357

High-speed spectral domain optical coherence tomography using non-uniform fast Fourier transform  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The useful imaging range in spectral domain optical coherence tomography (SD-OCT) is often limited by the depth dependent sensitivity fall-off. Processing SD-OCT data with the non-uniform fast Fourier transform (NFFT) can improve the sensitivity fall-off at maximum depth by greater than 5dB concurre...

Chan, Kenny K. H.; Tang, Shuo

358

Complex conjugate resolved heterodyne swept source optical coherence tomography using coherence revival  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We describe a simple and low-cost technique for resolving the complex conjugate ambiguity in Fourier domain optical coherence tomography (OCT) that is applicable to many swept source OCT (SSOCT) systems. First, we review the principles of coherence revival, wherein an interferometer illuminated by a...

Dhalla, Al-Hafeez; Nankivil, Derek; Izatt, Joseph A.

359

Segmentation of Doppler optical coherence tomography signatures using a support-vector machine  

Digital Repository Infrastructure Vision for European Research (DRIVER)

When processing Doppler optical coherence tomography images, there is a need to segment the Doppler signatures of the vessels. This can be used for visualization, for finding the center point of the flow areas or to facilitate the quantitative analysis of the vessel flow. We propose the use of a sup...

Singh, Amardeep S. G.; Schmoll, Tilman; Leitgeb, Rainer A.

360

Integrated photonic circuit in silicon on insulator for fourier domain optical coherence tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Optical coherence tomography (OCT) is a medical imaging technology capable of producing high-resolution, cross-sectional images through inhomogeneous samples, such as biological tissue. It has been widely adopted in clinical ophthalmology and a number of other clinical applications are in active res...

Izatt, JA; Fujimoto, JG; Tuchin, W; Yurtsever, Günay; Dumon, Pieter; Bogaerts, Wim; Baets, Roel

 
 
 
 
361

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present in vivo volumetric images of human retinal micro-circulation using Fourier-domain optical coherence tomography (Fd-OCT) with the phase-variance based motion contrast method. Currently fundus fluorescein angiography (FA) is the standard technique in clinical settings for visualizing blood ...

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

362

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

363

Optical coherence tomography in a patient with chloroquine-induced maculopathy  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We herein report the optical coherence tomography (OCT) findings in a case of chloroquine-induced macular toxicity, which to our knowledge, has so far not been reported. A 53-year-old lady on chloroquine for treatment of rheumatoid arthritis developed decrease in vision 36 months after initiation of...

Korah Sanita; Kuriakose Thomas

364

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Xu, Xiangqun; Yu, Lingfeng; Chen, Zhongping

365

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

Polarization sensitive optical coherence tomography (PS-OCT) is a functional extension of OCT. In addition to imaging based on tissue reflectivity, PS-OCT also enables depth-resolved mapping of sample polarization properties such as phase-retardation, birefringent axis orientation, Stokes vectors, a...

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

366

Comprehensive investigation of three-dimensional diffuse optical tomography with depth compensation algorithm  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A depth compensation algorithm (DCA) can effectively improve the depth localization of diffuse optical tomography (DOT) by compensating the exponentially decreased sensitivity in the deep tissue. In this study, DCA is investigated based on computer simulations, tissue phantom experiments, and human ...

Niu, Haijing; Lin, Zi-Jing; Tian, Fenghua; Dhamne, Sameer; Liu, Hanli

367

Sparsity enhanced spatial resolution and depth localization in diffuse optical tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract: In diffuse optical tomography (DOT), researchers often face challenges to accurately recover the depth and size of the reconstructed objects. Recent development of the Depth Compensation Algorithm (DCA) solves the depth localization problem, but the reconstructed images commonly exhibit ov...

Kavuri, Venkaiah C.; Lin, Zi-Jing; Tian, Fenghua; Liu, Hanli

368

Ultra-Fast Displaying Spectral Domain Optical Doppler Tomography System Using a Graphics Processing Unit  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We demonstrate an ultrafast displaying Spectral Domain Optical Doppler Tomography system using Graphics Processing Unit (GPU) computing. The calculation of FFT and the Doppler frequency shift is accelerated by the GPU. Our system can display processed OCT and ODT images simultaneously in real time a...

Hyosang Jeong; Nam Hyun Cho; Unsang Jung; Changho Lee; Jeong-Yeon Kim; Jeehyun Kim

369

Spectral-domain optical coherence tomography in lightning-induced maculopathy.  

UK PubMed Central (United Kingdom)

The authors report a case of lightning-induced chorioretinal burn accompanied by mild anterior segment injuries. Spectral-domain optical coherence tomography images were used to document the progressive retinal and choroidal changes. As evidenced by this report, despite being sight-threatening, such injuries may allow for a significant functional recovery.

Stefaniotou M; Katsanos A; Kaloudis A; Vourda E; Anthis N

2012-01-01

370

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

371

Handheld miniature probe integrating diffuse optical tomography with photoacoustic imaging through a MEMS scanning mirror.  

UK PubMed Central (United Kingdom)

We describe a novel dual-modality imaging approach that integrates diffuse optical tomography (DOT) and photoacoustic imaging (PAI) through a miniaturized handheld probe based on microelectromechanical systems (MEMS) scanning mirror. We validate this dual-modal DOT/PAI approach using extensive phantom experiments, and demonstrate its application for tumor imaging using tumor-bearing mice systematically injected with targeted contrast agents.

Yang H; Xi L; Samuelson S; Xie H; Yang L; Jiang H

2013-03-01

372

Reorganization of Photoreceptor Layer on Optical Coherence Tomography Concurrent with Visual Improvement after Macular Hole Surgery  

Digital Repository Infrastructure Vision for European Research (DRIVER)

To report three cases in which reorganization of the photoreceptor layer on optical coherence tomography (OCT) was concurrent with long-term visual recovery after macular hole surgery. Serial OCT scans of three eyes in which visual acuity continued to improve for 1 or more years after successful mac...

Lee, Ji Eun; Lee, Seung Uk; Jea, Seung Youn; Choi, Hee Young; Oum, Boo Sup

373

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.

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

2013-01-01

374

Optical coherence tomography-guided facedown positioning for macular hole surgery.  

UK PubMed Central (United Kingdom)

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.

Shah SP; Manjunath V; Rogers AH; Baumal CR; Reichel E; Duker JS

2013-02-01

375

Postsurgical evaluation of idiopathic vitreomacular traction syndrome by optical coherence tomography.  

UK PubMed Central (United Kingdom)

PURPOSE: To report a case of idiopathic vitreomacular traction syndrome with preoperative and postoperative evaluation by optical coherence tomography. DESIGN: Interventional case report. METHODS: A 62-year-old woman presented with blurred vision in the left eye because of idiopathic vitreomacular traction syndrome, and she underwent a pars plana vitrectomy. Optical coherence tomography was performed before and after surgery. RESULTS: Preoperative optical coherence tomography, right eye, revealed residual adhesion of incomplete posterior vitreous detachment and edematous, thickened outer retina in the macula. A successful vitrectomy relieved vitreoretinal traction with nearly complete resolution of cystoid macular edema within 1 month after surgery, followed in subsequent months by gradual foveal depression resembling a lamellar macular hole. Resolution of subretinal serous fluid was delayed with complete disappearance, some 12 months after surgery, which correlated with a gradual improvement in visual acuity. CONCLUSION: Optical coherence tomography provides a sensitive anatomical evaluation of vitreomacular traction syndrome. Reorganization of retinal tissue after surgical intervention for vitreoretinal traction may be slower than is apparent from conventional examinations.

Uchino E; Uemura A; Doi N; Ohba N

2001-07-01

376

Ten Years of Severe Vitreomacular Traction Syndrome without Functional Damage Demonstrated by Optical Coherence Tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Introduction. To describe anatomical and functional features in one patient with 10 years of severe vitreomacular traction syndrome (VTS) without functional damage demonstrated by optical coherence tomography (OCT). Patient and Methods. One patient with a history of 10 years VTS, with best-correcte...

Reibaldi, Michele; Avitabile, Teresio; Uva, Maurizio Giacinto; Occhipinti, Francesco; Toro, Mario; Zagari, Marco

377

Mechanism of a reproducible accordion phenomenon: insights by optical coherence tomography visualization.  

UK PubMed Central (United Kingdom)

Pseudostenosis or 'accordion phenomenon' is a transient angiographic multifocal filling defect observed mostly during percutaneous coronary intervention, mainly in tortuous vessels. We describe a case of a reproducible accordion effect in the right coronary artery accompanied by only a mild clinical syndrome. Optical coherence tomography evaluation of this strange and fortunately completely reversible phenomenon is discussed.

Tsigkas G; Karantalis V; Alexopoulos D

2011-08-01

378

Mechanism of a reproducible accordion phenomenon: insights by optical coherence tomography visualization.  

Science.gov (United States)

Pseudostenosis or 'accordion phenomenon' is a transient angiographic multifocal filling defect observed mostly during percutaneous coronary intervention, mainly in tortuous vessels. We describe a case of a reproducible accordion effect in the right coronary artery accompanied by only a mild clinical syndrome. Optical coherence tomography evaluation of this strange and fortunately completely reversible phenomenon is discussed. PMID:21597382

Tsigkas, Grigorios; Karantalis, Vasileios; Alexopoulos, Dimitrios

2011-08-01

379

Optical coherence tomography versus visual evoked potential in multiple sclerosis patients  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Background: Optical coherence tomography (OCT) is anon-invasive instrument, which can be used to estimate thethickness of the retinal nerve fibre layer (RNFL) and providesan indirect measurement of axonal destruction in multiplesclerosis (MS). The main aim of this study was to find out anycorrelatio...

Farzad Fatehi; Vahid Shaygannejad; Lida Kiani Mehr; Alireza Dehghani

380

Evaluation of central serous retinopathy with en face optical coherence tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Background: The diagnosis of idiopathic central serous retinopathy (CSR) is usually based on biomicroscopy and fluorescein angiography (FA). The optical coherence tomography (OCT) ophthalmoscope produces en face OCT scans (OCT C-scans) and provides additional information not readily available by con...

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

 
 
 
 
381

Miniature probe combining optical-resolution photoacoustic microscopy and optical coherence tomography for in vivo microcirculation study.  

UK PubMed Central (United Kingdom)

Photoacoustic microscopy (PAM) is sensitive to optical absorption, while optical coherence tomography (OCT) is based on optical backscattering. Combining PAM and OCT can provide complementary information about biological tissue. Here we present a combined optical-resolution PAM (ORPAM) and OCT system that is integrated through a miniature probe with an overall diameter of 2.3 mm, suitable for insertion through a standard endoscopic or laparoscopic port during minimally invasive surgery or endoscopic exam. The hybrid probe consists of a common optical path for OCT (light delivery/detection) and ORPAM (light excitation) and a 10 MHz unfocused ultrasound transducer for photoacoustic detection. The combined system yields a lateral resolution of 15 ?m for both ORPAM and OCT.

Xi L; Duan C; Xie H; Jiang H

2013-03-01

382

Spectral-domain optical coherence tomography imaging of drusenoid pigment epithelial detachments.  

UK PubMed Central (United Kingdom)

PURPOSE: To evaluate drusenoid retinal pigment epithelial detachments (DPED) secondary to age-related macular degeneration (AMD) using spectral-domain optical coherence tomography imaging. METHODS: In this prospective natural history study, eyes from patients with the diagnosis of nonexudative AMD and DPEDs were followed for at least 6 months. Eyes were scanned using the Cirrus spectral-domain optical coherence tomography instrument and the 200 × 200 A-scan raster pattern. A custom software was used to quantify volumetric changes in DPEDs and to detect the evolution and formation of geographic atrophy and choroidal neovascularization. Changes in DPED area and volume and development of the advanced forms of AMD were the main outcome. RESULTS: Of the 130 patients (186 eyes) with nonadvanced AMD, 11 patients (16 eyes) presented with DPEDs during the study. Mean follow-up was 18.5 months. Most DPEDs had an area exceeding 1 disk area (14 of 16 eyes) based on color fundus images with a mean area of 4.19 mm (SD = 1.35) measured by spectral-domain optical coherence tomography. The mean volume at the time the DPED was diagnosed was 0.48 mm (SD = 0.28). Four different patterns of progression were observed: DPEDs remained unchanged in 8 of 16 eyes (50%), DPEDs tended to increase in volume before progressing to geographic atrophy in 5 eyes (31.25%) and choroidal neovascularization in 2 eyes (12.5%), and a DPED decreased by more than 50% without progressing to geographic atrophy or choroidal neovascularization in 1 eye (6.25%). CONCLUSION: Spectral-domain optical coherence tomography imaging is able to detect subtle changes in the area and volume of DPEDs. Quantitative spectral-domain optical coherence tomography imaging of DPEDs is useful for identifying the natural history of disease progression and as a clinical tool for monitoring eyes with AMD in clinical trials.

Alexandre de Amorim Garcia Filho C; Yehoshua Z; Gregori G; Farah ME; Feuer W; Rosenfeld PJ

2013-09-01

383

Stereoscopic optical coherence tomography in the frequency domain for refractive index sensitive imaging  

Science.gov (United States)

A novel dual angle optical coherence tomography (OCT) method is developed that has been termed stereoscopic OCT, highlighting the similarities between this technique and stereoscopic ranging. OCT images are obtained at two angles of incidence with respect to the surface of a layered phantom. From these measurements, optical path lengths are determined for each layer that are used to calculate the refractive index and physical thickness of each layer directly from Snell's law. This method may prove to be useful for characterising the bulk optical properties of biological material in vivo, that are presently not well known or understood.

Tomlins, Peter H.; Tedaldi, Matthew; Ferguson, Robert A.; Wang, Ruikang K.

2007-08-01

384

Correlations between digital planimetry and optical coherence tomography, confocal scanning laser ophthalmoscopy in assessment of optic disc parameters.  

UK PubMed Central (United Kingdom)

UNLABELLED: OBJECTIVE AND AIM: In routine clinical practice, laser methods for the evaluation of optic disc parameters are expensive and not accessible for all ophthalmologists; therefore, there is a need for less expensive technique. The aim of this study was to assess correlations between the parameters of the optic disc measured by digital planimetry (DP), optical coherence tomography (OCT), and confocal scanning laser ophthalmoscopy (CSLO) in healthy and glaucoma patients with the normal biometric parameters of the eye. MATERIAL AND METHODS: This case-control study enrolled 40 patients with glaucoma and 32 healthy patients with the normal biometric parameters of the eye. All subjects underwent full ophthalmologic examination, digital color optic disc photography, OCT, and CSLO at the same visit. The optic disc was morphometrically analyzed by DP, OCT, and CSLO. Seven optic disc parameters were evaluated. RESULTS: In the glaucoma group, the optic disc and cup areas (r=0.7-0.8, P<0.001) and cup-to-optic disc and rim-to-optic disc area ratios (r=0.7, P<0.001) measured by DP were strongly correlated with those measured by OCT and CSLO, while the horizontal and vertical cup-to-optic disc diameter ratios were found to be moderately correlated (r=0.6-0.7, P<0.001). In healthy patients, the optic disc and cup areas were strongly correlated (r=0.7-8.0, P<0.001). Significant differences in all optic disc parameters, except for the optic disc area, measured by DP, OCT, and CSLO were found between glaucoma and healthy patients. CONCLUSIONS: Strong correlations between the parameters of the optic disc measured by DP, OCT, and CSLO were found. There were significant differences in the parameters between healthy and glaucoma eyes measured using DP; therefore, this technique may be used for diagnosis, management, and screening of glaucoma.

Buteikien? D; Paunksnis A; Barzdžiukas V; Zali?nien? D; Bal?i?nien? JV; Jegelevi?ius D

2012-01-01

385

[Optical coherence tomography in monitoring of choroidal folds after surgical excision of ethmoidal myxoma].  

UK PubMed Central (United Kingdom)

PURPOSE: We describe a case of choroidal folds coexisting with ethmoidal myxoma and the evolution of folds after tumor excision. Choroidal folds can occure in the case of intraorbital pathology. Optical coherence tomography is usefull in diagnosis and monitoring of these folds. MATERIAL AND METHODS: 45 years old woman was reffered to our clinic because of visal disturbances in her right eye. Visual acuity of right eye was 0.5, of the left eye 1.0. Intraocular pressure of both eyes was within normal limits. Biomicroscopic evaluation of the right eye revealed no changes in anterior segment but choroidal folds in posterior segment were evident. The left eye was normal. Computer tomography of the orbit documented the presence of tumor within the right ethmoid. The tumor was excised surgically and its myxoidal nature was confirmed. RESULTS: 3 months after that intervention retinal profile in posterior pole in optical coherence tomography was normal and visual acuity of right eye improved by 1 line in Snellen chart. CONCLUSIONS: Choroidal folds caused by ethmoidal myxoma can disapper after surgical excison of tumor. Optical coherence tomography is very useful in documentation of these changes.

Zubilewicz A; Dolar-Szczasny J; Rakowska E; Mackiewicz J

2013-01-01

386

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

International Nuclear Information System (INIS)

[en] 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

2007-04-02

387

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

Science.gov (United States)

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

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

2013-02-01

388

Image enhancement for multilayer information retrieval by using full-field optical coherence tomography.  

Science.gov (United States)

When a full-field optical coherence tomography (OCT) system is used to extract tomographic images from a multilayer information carrier, the resulting images may suffer from interlayer modulations and parasitic patterns derived from interference fringes. We describe and analyze these negative influences that degrade the quality of extracted tomographic images and propose practical algorithms and methods to minimize them. The emphasis of the discussion will be the removal of the parasitic fringes produced by the imperfection of a CCD camera. The simulative and experimental results of image enhancement for multilayer tomography extraction using full-field OCT are provided. PMID:16926885

Chang, Shoude; Cai, Xianyang; Flueraru, Costel

2006-08-10

389

Corneal thickness in keratoconus: comparing optical, ultrasound, and optical coherence tomography pachymetry.  

UK PubMed Central (United Kingdom)

PURPOSE: To compare the central and peripheral pachymetry measurements determined using Orbscan IIz (Bausch & Lomb, Rochester, NY), Visante optical coherence tomography (OCT; Carl Zeiss Meditec, Dublin, CA), and RTVue OCT (Oculus Technologies, Wynwood, WA) with ultrasound pachymetry in eyes with established keratoconus and to evaluate the agreement between them. DESIGN: Evaluation of diagnostic technologies. PARTICIPANTS: One hundred six eyes of 67 consecutive patients with a clinical diagnosis of keratoconus ranging in age from 12 to 40 years. METHODS: Central corneal thickness (CCT) was determined by all the 4 techniques. Peripheral corneal thicknesses were determined using Orbscan IIz, Visante OCT, and RTVue at 8 points (superior, inferior, temporal, nasal, superior-temporal, inferior-temporal, superior-nasal, and inferior-nasal) all in the 5.0- to 7.0-mm arcuate zone. MAIN OUTCOME MEASURES: Central and peripheral keratoconus thickness. RESULTS: Ultrasound pachymetry determined significantly higher CCT values than Orbscan IIz (P<0.001), Visante (P<0.001), and RTVue (P = 0.037), with a mean ± standard deviation difference of 14±3 ?m, 13±2 ?m, and 5±3 ?m, respectively. The mean CCT difference was minimal (1±3 ?m; P = 0.69) between the Orbscan IIz and Visante. A strong correlation was found (r>0.80) between all the CCT measurement techniques. Orbscan IIz significantly overestimated the peripheral thickness compared with the rest, and the mean differences ranged between 21 and 60 ?m. Mean peripheral thickness differences between RTVue and Visante OCT always remained less than 20 ?m. Weak correlations and larger limits of agreement were found between the techniques in thinner and peripheral zones. CONCLUSIONS: Orbscan IIz, Visante, RTVue, and ultrasound pachymetry show high correlation, although Orbscan IIz and Visante significantly underestimated CCT measurements compared with ultrasound pachymetry in keratoconus. Orbscan IIz significantly overestimated peripheral corneal thickness compared with RTVue and Visante.

Dutta D; Rao HL; Addepalli UK; Vaddavalli PK

2013-03-01

390

Dependence of optical attenuation coefficient and mechanical tension of irradiated human cartilage measured by optical coherence tomography.  

UK PubMed Central (United Kingdom)

As banked human tissues are not widely available, the development of new non-destructive and contactless techniques to evaluate the quality of allografts before distribution for transplantation is very important. Also, tissues will be processed accordingly to standard procedures and to minimize disease transmission most tissue banks will include a decontamination or sterilization step such as ionizing radiation. In this work, we present a new method to evaluate the internal structure of frozen or glycerol processed human cartilages, submitted to various dosis of irradiation, using the total optical attenuation coefficient retrieved from optical coherence tomography (OCT) images. Our results show a close relationship between tensile properties and the total optical attenuation coefficient of cartilages. Therefore, OCT associated with the total optical attenuation coefficient open a new window to evaluate quantitatively biological changes in processed tissues.

Martinho Jr AC; Freitas AZ; Raele MP; Santin SP; Soares FA; Herson MR; Mathor MB

2013-07-01

391

Real-time subglottic stenosis imaging using optical coherence tomography in the rabbit.  

UK PubMed Central (United Kingdom)

IMPORTANCE: Subglottic stenosis (SGS) is a severe, acquired, potentially life-threatening disease that can be caused by endotracheal tube intubation. Newborns and neonates are particularly susceptible to SGS owing to the small caliber of their airway. OBJECTIVE: To demonstrate optical coherence tomography (OCT) capabilities in detecting injury and scar formation using a rabbit model. Optical coherence tomography may provide a noninvasive, bedside or intensive care unit modality for the identification of early airway trauma with the intention of preventing progression to SGS and can image the upper airway through an existing endotracheal tube coupled with a small fiber-optic probe. DESIGN: Rabbits underwent suspension laryngoscopy with induction of of SGS via epithelial injury. This model was used to test and develop our advanced, high-speed, high-resolution OCT imaging system using a 3-dimensional microelectromechanical systems-based scanning device integrated with a fiber-optic probe to acquire high-resolution anatomic images of the subglottic epithelium and lamina propria. SETTING: All experiments were performed at the Beckman Laser Institute animal operating room. INTERVENTION OR EXPOSURE: Optical coherence tomography and endoscopy was performed with suspension laryngoscopy at 6 different time intervals and compared with conventional digital endoscopic images and histologic sections. Fifteen rabbits were killed at 3, 7, 14, 21, and 42 days after the induction of SGS. The laryngotracheal complexes were serially sectioned for histologic analysis. MAIN OUTCOME AND MEASURE: Histologic sections, endoscopic images, and OCT images were compared with one another to determine if OCT could accurately delineate the degree of SGS achieved. RESULTS: The rabbit model was able to reliably and reproducibly achieve grade I SGS. The real-time OCT imaging system was able to (1) identify multiple structures in the airway; (2) delineate different tissue planes, such as the epithelium, basement membrane, lamina propria, and cartilage; and (3) detect changes in each tissue plane produced by trauma. Optical coherence tomography was also able demonstrate a clear picture of airway injury that correlated with the endoscopic and histologic images. With subjective review, 3 patients had high correlation between OCT and histologic images, 10 demonstrated some correlation with histologic images, and 2 showed little to no correlation with histologic images. CONCLUSIONS AND RELEVANCE: Optical coherence tomography, coupled with a fiber-optic probe, identifies subglottic scarring and can detect tissue changes in the rabbit airway to a depth of 1 mm. This technology brings us 1 step closer to minimally invasive subglottic airway monitoring in the intubated neonate, with the ultimate goal of preventing SGS and better managing the airway.

Lin JL; Yau AY; Boyd J; Hamamoto A; Su E; Tracy L; Tracey L; Heidari AE; Wang AH; Ahuja G; Chen Z; Wong BJ

2013-05-01

392

Fundus Autofluorescence, Optical Coherence Tomography, and Electroretinogram Findings in Choroidal Sclerosis  

Science.gov (United States)

Purpose To describe fundus autofluorescence, optical coherence tomography, and electroretinogram findings in choroidal sclerosis. Methods Retrospective case series. Eight eyes of four patients with choroidal sclerosis were evaluated with fundus autofluorescence, optical coherence tomography, and electroretinogram testing. Results In all eight eyes, fundus autofluorescence imaging revealed hypofluorescent placoid lesions corresponding to areas of chorioretinal atrophy seen on stereo biomicroscopy. Prominent hyperfluorescent linear markings underlying regions of atrophic disease were observed in all eyes, likely representative of normal choroidal vessel autofluorescence. In two eyes, fundus autofluorescence revealed punctate hypofluorescent lesions in the fovea that were not visualized on biomicroscopy. In one eye, fundus autofluorescence identified a central island of preserved retinal pigment epithelium that was not appreciated on ophthalmoscopic examination. Optical coherence imaging was significant for loss of choroidal fine tubular structures, retinal pigment epithelium, and outer nuclear layer in regions of chorioretinal atrophy. Full-field electroretinogram testing demonstrated generalized rod-cone dysfunction in all patients with a lower b- to a- wave ratio in two patients. Conclusion Fundus autofluorescence and optical coherence tomography are noninvasive diagnostic adjunct that can aid in the diagnosis of choroidal sclerosis. Fundus autofluorescence may be a more sensitive marker of disease extent and progression than clinical exam alone. Electroretinogram testing can result in an electronegative maximal response.

Hwang, John C.; Kim, David Y.; Chou, Chai Lin; Tsang, Stephen H.

2010-01-01

393

Evaluation of peripapillary intrachoroidal cavitation with swept source and enhanced depth imaging optical coherence tomography.  

UK PubMed Central (United Kingdom)

PURPOSE: To investigate the anatomic characteristics of peripapillary intrachoroidal cavitation using optical coherence tomography methodologies that are capable of deeper tissue penetration and consider pathophysiologic mechanisms of disease on the basis of the derived imaging information. METHODS: Consecutive eyes with peripapillary intrachoroidal cavitation were imaged with swept source optical coherence tomography with a 1-mm light source and in one eye with enhanced depth imaging spectral domain optical coherence tomography and 3-dimensional rendering. The anatomic layers were identified, and the induced abnormalities were evaluated. RESULTS: There were 16 eyes of 13 patients who had a mean age of 50.3 years and a mean spherical refraction of -12.5 diopters in the affected eyes. The lesion appeared as a yellowish-orange lobular region, usually inferior to the optic nerve, which was invariably tilted. The sclera was bowed posteriorly under the region of the intrachoroidal cavitation, while the overlying retina-retinal pigment epithelium-Bruch membrane complex showed little, if any deformation. Full-thickness defects in the retina at the inferior border of the conus were seen in four eyes and were associated with prominent cavitation within the choroid with marked posterior bowing of the sclera, but negligible deformation of the overlying retina inferior to the nerve. CONCLUSION: Newer imaging modalities provided information about deeper structures in the eye not available in older studies that were performed with time-domain optical coherence tomography. This study demonstrated posterior deformation of the sclera in regions previously thinned by the ocular expansion that occurs in high myopia and imaged the resultant effects on the involved choroid.

Spaide RF; Akiba M; Ohno-Matsui K

2012-06-01

394

Parametric imaging of the local attenuation coefficient in human axillary lymph nodes assessed using optical coherence tomography  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We report the use of optical coherence tomography (OCT) to determine spatially localized optical attenuation coefficients of human axillary lymph nodes and their use to generate parametric images of lymphoid tissue. 3D-OCT images were obtained from excised lymph nodes and optical attenuation coeffic...

Scolaro, Loretta; McLaughlin, Robert A.; Klyen, Blake R.; Wood, Benjamin A.; Robbins, Peter D.; Saunders, Christobel M.

395

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

Directory of Open Access Journals (Sweden)

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; George J Parlitsis; Joshua R Ehrlich; et al

2010-01-01

396

Efficient tomography of quantum-optical Gaussian processes probed with a few coherent states  

Science.gov (United States)

An arbitrary quantum-optical process (channel) can be completely characterized by probing it with coherent states using the recently developed coherent-state quantum process tomography (QPT) [Lobino , ScienceSCIEAS0036-807510.1126/science.1162086 322, 563 (2008)]. In general, precise QPT is possible if an infinite set of probes is available. Thus, realistic QPT of infinite-dimensional systems is approximate due to a finite experimentally feasible set of coherent states and its related energy-cutoff approximation. We show with explicit formulas that one can completely identify a quantum-optical Gaussian process just with a few different coherent states without approximations like the energy cutoff. For tomography of multimode processes, our method exponentially reduces the number of different test states, compared with existing methods.

Wang, Xiang-Bin; Yu, Zong-Wen; Hu, Jia-Zhong; Miranowicz, Adam; Nori, Franco

2013-08-01

397

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.

2005-10-07

398

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

Directory of Open Access Journals (Sweden)

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; Danis Ronald; Myers Dawn; Kruse Christina

2010-01-01

399

Depiction of cavity formation in Terrien marginal degeneration by anterior segment optical coherence tomography.  

UK PubMed Central (United Kingdom)

PURPOSE: To evaluate detailed morphologic changes of Terrien marginal degeneration (TMD) using anterior segment optical coherence tomography (AS-OCT). METHODS: Two patients with TMD were examined by 1310-nm wavelength swept source optical coherence tomography, corneal topography, and slit-lamp microscopy. RESULTS: AS-OCT depicted corneal thinning with intact epithelial layer in the peripheral cornea of both patients. Moreover, AS-OCT images of both patients clearly showed cavity formation surrounded and enclosed by intact epithelial and endothelial layers in the thinned area. CONCLUSION: We demonstrate here the existence of cavity formation in the peripheral cornea with TMD. This observation suggests a possibility that corneal thinning in TMD is associated with cavity formation in the corneal stroma. AS-OCT is useful for the observation of detailed morphologic changes of diseased cornea.

Hattori T; Kumakura S; Mori H; Goto H

2013-05-01

400

Optical coherence tomography to detect macular edema in the presence of asteroid hyalosis.  

UK PubMed Central (United Kingdom)

PURPOSE: To propose the use of optical coherence tomography as an effective diagnostic tool for identifying macular edema in patients with asteroid hyalosis obscuring the fundus view. DESIGN: Case report. METHODS: Review of clinical chart and images. SETTING: Private retina practice. PATIENT: One patient diagnosed with diabetic retinopathy and asteroid hyalosis, who was experiencing decreased visual acuity and whose fundus view was inadequate for diagnosis using customary techniques. RESULTS: Usual methods of diagnosis were ineffective until OCT obtained a clear image of the fundus and subsequent macular thickening with vitreomacular adhesion. CONCLUSIONS: Optical coherence tomography is an effective diagnostic tool for discovering macular edema in cases of dense asteroid hyalosis where traditional methods fail to obtain a clear image of the fundus.

Browning DJ; Fraser CM

2004-05-01

 
 
 
 
401

Two cases of X-linked retinoschisis with different spectral domain optical coherence tomography findings  

Directory of Open Access Journals (Sweden)

Full Text Available Theodore LengByers Eye Institute at Stanford, Stanford University School of Medicine, Palo Alto, CA, USAAbstract: Spectral domain optical coherence tomography was used to image the maculae of two brothers who had the diagnosis of X-linked retinoschisis maculopathy. One patient demonstrated a large foveal cyst in one eye and a lamellar macular hole in the fellow eye. The second patient demonstrated small retinal cysts in multiple layers of the retina. Spectral domain optical coherence tomography allowed high-resolution imaging and characterization of the features in X-linked retinoschisis in these patients, and it highlighted the variability of the same genetic disease, even in one family.Keywords: SD-OCT, XLRS, retina, imaging, maculopathy

Leng T

2012-01-01

402

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

International Nuclear Information System (INIS)

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

2010-01-01

403

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, A; Fauser, S; Kirchhof, B

404

In vivo lung microvasculature visualized in three dimensions using fiber-optic color Doppler optical coherence tomography  

Science.gov (United States)

For the first time, the use of fiber-optic color Doppler optical coherence tomography (CDOCT) to map in vivo the three-dimensional (3-D) vascular network of airway segments in human lungs is demonstrated. Visualizing the 3-D vascular network in the lungs may provide new opportunities for detecting and monitoring lung diseases such as asthma, chronic obstructive pulmonary disease, and lung cancer. Our CDOCT instrument employs a rotary fiber-optic probe that provides simultaneous two-dimensional (2-D) real-time structural optical coherence tomography (OCT) and CDOCT imaging at frame rates up to 12.5 frames per second. Controlled pullback of the probe allows 3-D vascular mapping in airway segments up to 50 mm in length in a single acquisition. We demonstrate the ability of CDOCT to map both small and large vessels. In one example, CDOCT imaging allows assignment of a feature in the structural OCT image as a large (˜1 mm diameter) blood vessel. In a second example, a smaller vessel (˜80 ?m diameter) that is indistinguishable in the structural OCT image is fully visualized in 3-D using CDOCT.

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

2013-05-01

405

Multiple Fan-Beam Optical Tomography: Modelling Techniques  

Directory of Open Access Journals (Sweden)

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

Ruzairi Abdul Rahim; Leong Lai Chen; Chan Kok San; Mohd Hafiz Fazalul Rahiman; Pang Jon Fea

2009-01-01

406

Depth resolved detection of lipid using spectroscopic optical coherence tomography.  

UK PubMed Central (United Kingdom)

Optical frequency domain imaging (OFDI) can identify key components related to plaque vulnerability but can suffer from artifacts that could prevent accurate identification of lipid rich regions. In this paper, we present a model of depth resolved spectral analysis of OFDI data for improved detection of lipid. A quadratic Discriminant analysis model was developed based on phantom compositions known chemical mixtures and applied to a tissue phantom of a lipid-rich plaque. We demonstrate that a combined spectral and attenuation model can be used to predict the presence of lipid in OFDI images.

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