Showing papers on "Optical coherence tomography published in 2003"
TL;DR: Results are presented which demonstrate the superior sensitivity of swept source (SS) and Fourier domain (FD) optical coherence tomography (OCT) techniques over the conventional time domain (TD) approach.
Abstract: We present theoretical and experimental results which demonstrate the superior sensitivity of swept source (SS) and Fourier domain (FD) optical coherence tomography (OCT) techniques over the conventional time domain (TD) approach. We show that SS- and FD-OCT have equivalent expressions for system signal-to-noise ratio which result in a typical sensitivity advantage of 20-30dB over TD-OCT. Experimental verification is provided using two novel spectral discrimination (SD) OCT systems: a differential fiber-based 800nm FD-OCT system which employs deep-well photodiode arrays, and a differential 1300nm SS-OCT system based on a swept laser with an 87nm tuning range.
2,109 citations
TL;DR: It is shown that FDOCT systems have a large sensitivity advantage and allow for sensitivities well above 80dB, even in situations with low light levels and high speed detection.
Abstract: In this article we present a detailed discussion of noise sources in Fourier Domain Optical Coherence Tomography (FDOCT) setups. The performance of FDOCT with charge coupled device (CCD) cameras is compared to current standard time domain OCT systems. We describe how to measure sensitivity in the case of FDOCT and confirm the theoretically obtained values. It is shown that FDOCT systems have a large sensitivity advantage and allow for sensitivities well above 80dB, even in situations with low light levels and high speed detection.
2,104 citations
TL;DR: OCT as discussed by the authors synthesises cross-sectional images from a series of laterally adjacent depth-scans, which can be used to assess tissue and cell function and morphology in situ.
Abstract: There have been three basic approaches to optical tomography since the early 1980s: diffraction tomography, diffuse optical tomography and optical coherence tomography (OCT). Optical techniques are of particular importance in the medical field, because these techniques promise to be safe and cheap and, in addition, offer a therapeutic potential. Advances in OCT technology have made it possible to apply OCT in a wide variety of applications but medical applications are still dominating. Specific advantages of OCT are its high depth and transversal resolution, the fact, that its depth resolution is decoupled from transverse resolution, high probing depth in scattering media, contact-free and non-invasive operation, and the possibility to create various function dependent image contrasting methods. This report presents the principles of OCT and the state of important OCT applications. OCT synthesises cross-sectional images from a series of laterally adjacent depth-scans. At present OCT is used in three different fields of optical imaging, in macroscopic imaging of structures which can be seen by the naked eye or using weak magnifications, in microscopic imaging using magnifications up to the classical limit of microscopic resolution and in endoscopic imaging, using low and medium magnification. First, OCT techniques, like the reflectometry technique and the dual beam technique were based on time-domain low coherence interferometry depth-scans. Later, Fourier-domain techniques have been developed and led to new imaging schemes. Recently developed parallel OCT schemes eliminate the need for lateral scanning and, therefore, dramatically increase the imaging rate. These schemes use CCD cameras and CMOS detector arrays as photodetectors. Video-rate three-dimensional OCT pictures have been obtained. Modifying interference microscopy techniques has led to high-resolution optical coherence microscopy that achieved sub-micrometre resolution. This report is concluded with a short presentation of important OCT applications. Ophthalmology is, due to the transparent ocular structures, still the main field of OCT application. The first commercial instrument too has been introduced for ophthalmic diagnostics (Carl Zeiss Meditec AG). Advances in using near-infrared light, however, opened the path for OCT imaging in strongly scattering tissues. Today, optical in vivo biopsy is one of the most challenging fields of OCT application. High resolution, high penetration depth, and its potential for functional imaging attribute to OCT an optical biopsy quality, which can be used to assess tissue and cell function and morphology in situ. OCT can already clarify the relevant architectural tissue morphology. For many diseases, however, including cancer in its early stages, higher resolution is necessary. New broad-bandwidth light sources, like photonic crystal fibres and superfluorescent fibre sources, and new contrasting techniques, give access to new sample properties and unmatched sensitivity and resolution.
1,914 citations
TL;DR: A signal-to-noise ratio (SNR) analysis is presented for optical coherence tomography (OCT) signals in which time-domain performance is compared with that of the spectral domain.
Abstract: A signal-to-noise ratio (SNR) analysis is presented for optical coherence tomography (OCT) signals in which time-domain performance is compared with that of the spectral domain. A significant SNR gain of several hundredfold is found for acquisition in the spectral domain. The SNR benefit is demonstrated experimentally in a hybrid time-domain-spectral-domain OCT system.
1,505 citations
TL;DR: It is derived and shown experimentally that frequency- domain ranging provides a superior signal-to-noise ratio compared with conventional time-domain ranging as used in optical coherence tomography.
Abstract: We demonstrate high-speed, high-sensitivity, high-resolution optical imaging based on optical frequency-domain interferometry using a rapidly-tuned wavelength-swept laser. We derive and show experimentally that frequency-domain ranging provides a superior signal-to-noise ratio compared with conventional time-domain ranging as used in optical coherence tomography. A high sensitivity of -110 dB was obtained with a 6 mW source at an axial resolution of 13.5 microm and an A-line rate of 15.7 kHz, representing more than an order-of-magnitude improvement compared with previous OCT and interferometric imaging methods.
1,067 citations
TL;DR: Optical coherence tomography functions as a type of 'optical biopsy' to provide cross-sectional images of tissue structure on the micron scale and is a promising imaging technology because it can provide images of tissues in situ and in real time, without the need for excision and processing of specimens.
Abstract: Optical coherence tomography (OCT) is an emerging biomedical optical imaging technique that performs high-resolution, cross-sectional tomographic imaging of microstructure in biological systems. OCT can achieve image resolutions of 1-15 microm, one to two orders of magnitude finer than standard ultrasound. The image penetration depth of OCT is determined by the optical scattering and is up to 2-3 mm in tissue. OCT functions as a type of 'optical biopsy' to provide cross-sectional images of tissue structure on the micron scale. It is a promising imaging technology because it can provide images of tissue in situ and in real time, without the need for excision and processing of specimens.
1,031 citations
TL;DR: An ultra-high-speed spectral domain optical Doppler tomography system is used to acquire images of blood flow in a human retina in vivo, at 29,000 depth profiles per second and with data acquisition over 99% of the measurement time.
Abstract: An ultra-high-speed spectral domain optical Doppler tomography (SD-ODT) system is used to acquire images of blood flow in a human retina in vivo, at 29,000 depth profiles (A-lines) per second and with data acquisition over 99% of the measurement time. The phase stability of the system is examined and image processing algorithms are presented that allow accurate determination of bi-directional Doppler shifts. Movies are presented of human retinal flow acquired at 29 frames per second with 1000 A-lines per frame over a time period of 3.28 seconds, showing accurate determination of vessel boundaries and time-dependent bi-directional flow dynamics in artery-vein pairs. The ultra-high-speed SD-ODT system allows visualization of the pulsatile nature of retinal blood flow, detects blood flow within the choroid and retinal capillaries, and provides information on the cardiac cycle. In summary, accurate video rate imaging of retinal blood flow dynamics is demonstrated at ocular exposure levels below 600 microW.
587 citations
TL;DR: Ultrahigh-resolution ophthalmic OCT enables unprecedented visualization of intraretinal morphologic features and therefore has the potential to contribute to a better understanding of ocular pathogenesis, as well as to enhance the sensitivity and specificity for early ocular diagnosis and to monitor the efficacy of therapy.
Abstract: Objectives To demonstrate a new generation of ophthalmic optical coherence tomography(OCT) technology with unprecedented axial resolution for enhanced imaging of intraretinal microstructures and to investigate its clinical feasibility to visualize intraretinal morphology of macular pathology. Methods A clinically viable ultrahigh-resolution ophthalmic OCT system was developed and used in clinical imaging for the first time. Fifty-six eyes of 40 selected patients with different macular diseases including macular hole, macular edema, age-related macular degeneration, central serous chorioretinopathy, epiretinal membranes, and detachment of pigment epithelium and sensory retina were included. Outcome Measures Ultrahigh-resolution tomograms visualizing intraretinal morphologic features in different retinal diseases. Results An axial image resolution of approximately 3 µm was achieved in the eyes examined, nearly 2 orders of magnitude better than conventional ophthalmic ultrasound. Ultrahigh-resolution OCT images provided additional diagnostically important information on intraretinal morphologic features that could not have been obtained by standard techniques. Conclusions Ultrahigh-resolution ophthalmic OCT enables unprecedented visualization of intraretinal morphologic features and therefore has the potential to contribute to a better understanding of ocular pathogenesis, as well as to enhance the sensitivity and specificity for early ophthalmic diagnosis and to monitor the efficacy of therapy. This study establishes a baseline for the interpretation of ultrahigh-resolution ophthalmic OCT imaging of macular diseases.
549 citations
TL;DR: The interfaced color Doppler Fourier domain optical coherence tomography (CD-FDOCT) with a commercial OCT system to perform in vivo studies of human retinal blood flow in real time and achieves a system sensitivity of 86dB using a beam power of 500microW at the cornea.
Abstract: We interfaced color Doppler Fourier domain optical coherence tomography (CD-FDOCT) with a commercial OCT system to perform in vivo studies of human retinal blood flow in real time. FDOCT does not need reference arm scanning and records one full depth and Doppler profile in parallel. The system operates with an equivalent A-scan rate of 25 kHz and allows real time imaging of the color encoded Doppler information together with the tissue morphology at a rate of 2-4 tomograms (40 x 512 pixel) per second. The recording time of a single tomogram (160 x 512 data points) is only 6,4ms. Despite the high detection speed we achieve a system sensitivity of 86dB using a beam power of 500microW at the cornea. The fundus camera allows simultaneous view for selection of the region of interest. We observe bi-directional blood flow and pulsatility of blood velocity in retinal vessels with a Doppler detection bandwidth of 12.5 kHz and a longitudinal velocity sensitivity in tissue of 200microm/s.
536 citations
TL;DR: Both macular and NFL thickness as measured by OCT showed statistically significant correlations with glaucoma, although NFL thickness showed a stronger association than macular thickness.
519 citations
TL;DR: In this paper, a spectral domain optical coherence tomography (SD-OCT) system was proposed to acquire individual axial scans in 24.4 micros at a rate of 19,000 axial images per second, using an InGaAs line scan camera and broadband light source centered at 1.31microm.
Abstract: We demonstrate a high-speed spectral domain optical coherence tomography (SD-OCT) system capable of acquiring individual axial scans in 24.4 micros at a rate of 19,000 axial scans per second, using an InGaAs line scan camera and broadband light source centered at 1.31microm. Sensitivity of >105 dB over a 2-mm depth range was obtained with a free-space axial resolution of 12-14 microm, in agreement with our signal-to-noise ratio predictions. Images of human tissue obtained in vivo with SD-OCT show similar penetration depths to those obtained with state-of-the-art time domain OCT despite the ten-fold higher image acquisition speed. These results demonstrate the potential of 1.3 microm SD-OCT for high-speed and high-sensitivity imaging in patients.
TL;DR: An improved spectral optical coherence tomography technique is used to obtain cross-sectional ophthalmic images at an exposure time of 64 micros per A-scan, which allows real-time images as well as static tomograms to be recorded in vivo.
Abstract: An improved spectral optical coherence tomography technique is used to obtain cross-sectional ophthalmic images at an exposure time of 64μs per A-scan. This method allows real-time images as well as static tomograms to be recorded in vivo.
TL;DR: The frequency compounding method based on incoherent summation of the magnitudes of two independent interferometric signals, which were recorded at two different center wavelengths simultaneously, results in an increased contrast and improved image quality without loss of resolution.
Abstract: We are investigating the possibility of a frequency compounding method for speckle reduction in optical coherence tomography. The method is based on incoherent summation of the magnitudes of two independent interferometric signals, which were recorded at two different center wavelengths simultaneously. We derive the corresponding statistics and compare the theoretical results with measurements obtained in a uniformly scattering sample. Finally we demonstrate our method by comparing images of human skin recorded in vivo with and without frequency compounding. The compounding method results in an increased contrast and improved image quality without loss of resolution.
TL;DR: A Michelson-type spectral interferometer that uses a common beam path for the reference and the sample arms is described, which is well suited for frequency-domain optical coherence tomography of biological samples.
Abstract: A Michelson-type spectral interferometer that uses a common beam path for the reference and the sample arms is described. This optical arrangement is more compact and stable than the more commonly used dual-arm interferometer and is well suited for frequency-domain optical coherence tomography of biological samples. With a 16-bit CCD camera, the instrument has sufficient dynamic range and resolution for imaging to depths of 2 mm in scattering biological materials. Images obtained with this spectral interferometer are presented, including cross-sectional images in a Xenopus laevis tadpole.
TL;DR: In vitro ophthalmic ultrahigh-resolution OCT imaging reveals retinal morphology with unprecedented detail, and the specific assignment of OCT signal patterns to retinal substructures provides a basis for improved interpretation of in vivoOCT tomograms of high clinical relevance.
Abstract: Purpose To compare ultrahigh-resolution optical coherence tomography (OCT) cross-sectional images of the pig retina with histology, to evaluate the potential of ultrahigh-resolution OCT for enhanced visualization of intra- and subretinal structures. Methods Ultrahigh-resolution OCT images were acquired with 1.4- micro m axial x 3- micro m transverse resolution from in vitro posterior eyecup preparations of the domestic pig. Frozen sections were obtained in precise alignment with OCT tomograms, by using major blood vessels as orientation markers and were counterstained with cresyl violet or unstained and examined by differential interference contrast microscopy. Micrographs from histologic sections were linearly scaled to correct for tissue shrinkage and compared with OCT tomograms. Results In the proximal retina, ultrahigh-resolution OCT signal bands directly corresponded to the main retinal layers. For the wavelength region used ( approximately 800 nm), axodendritic layers (nerve fiber layer, inner and outer plexiform layers) were more reflective than cell body layers (ganglion cell layer, inner nuclear layer, outer nuclear layer). In the distal retina, substructures of the photoreceptor layer such as the interface between inner and outer segments were visualized, and the retinal pigment epithelium, the choriocapillaris, and superficial choroid layers were resolved. In addition, the time sequence of a retinal detachment event was monitored by ultrahigh-resolution OCT. Conclusions In vitro ophthalmic ultrahigh-resolution OCT imaging reveals retinal morphology with unprecedented detail. The specific assignment of OCT signal patterns to retinal substructures provides a basis for improved interpretation of in vivo ophthalmic OCT tomograms of high clinical relevance.
TL;DR: An ultrahigh-resolution optical coherence tomographic system in which broadband continuum generation from a photonic crystal fiber is used to produce high longitudinal resolution is developed and subcellular imaging is demonstrated.
Abstract: We have developed an ultrahigh-resolution optical coherence tomographic system in which broadband continuum generation from a photonic crystal fiber is used to produce high longitudinal resolution. Longitudinal resolution of 1.3-microm has been achieved in a biological tissue by use of continuum light from 800 to 1400 nm. The system employed a dynamic-focusing tracking method to maintain high lateral resolution over a large imaging depth. Subcellular imaging is demonstrated.
TL;DR: A novel technique is presented that shows all the features of complex FDOCT with only two recorded interferograms, enabling standard phase-retrieval algorithms to double the measurement range.
Abstract: Standard Fourier-domain optical coherence tomography (FDOCT) suffers from the presence of autocorrelation terms that obscure the object information and degrade the sensitivity and signal-to-noise ratio. By exploiting the phase information of the recorded interferograms, it is possible to remove those autocorrelation terms and to double the measurement range. However, standard phase-retrieval algorithms need three to five interferograms. We present a novel technique that shows all the features of complex FDOCT with only two recorded interferograms.
TL;DR: Improvements in real-time Doppler optical coherence tomography (DOCT), acquiring up to 32 frames per second at 250 x 512 pixels per image, are reported using signal processing techniques commonly employed in Dopplers ultrasound imaging.
Abstract: Improvements in real-time Doppler optical coherence tomography (DOCT), acquiring up to 32 frames per second at 250×512 pixels per image, are reported using signal processing techniques commonly employed in Doppler ultrasound imaging. The ability to measure a wide range of flow velocities, ranging from less than 20 µm/s to more than 10 cm/s, is demonstrated using an 1.3 µm DOCT system with flow phantoms in steady and pulsatile flow conditions. Based on full implementation of a coherent demodulator, four different modes of flow visualization are demonstrated: color Doppler, velocity variance, Doppler spectrum, and power Doppler. The performance of the former two, which are computationally suitable for real-time imaging, are analyzed in detail under various signal-to-noise and frame-rate conditions. The results serve as a guideline for choosing appropriate imaging parameters for detecting in vivo blood flow.
TL;DR: The immunity of the quantum version to dispersion, as well as a factor of 2 enhancement in resolution, is experimentally demonstrated in quantum-optical coherence tomography.
Abstract: We present an experimental demonstration of quantum-optical coherence tomography. The technique makes use of an entangled twin-photon light source to carry out axial optical sectioning. It is compared to conventional optical coherence tomography. The immunity of the quantum version to dispersion, as well as a factor of 2 enhancement in resolution, is experimentally demonstrated.
TL;DR: In this paper, optical coherence tomography (OCT) was used to correlate macular thickness and retinal nerve fiber layer (RNFL) thickness in normal and glaucomatous eyes.
Abstract: Objective To correlate macular thickness and retinal nerve fiber layer (RNFL) thickness in normal and glaucomatous eyes using optical coherence tomography. Methods Complete examination, automated achromatic perimetry, and optical coherence tomography of the peripapillary RNFL and macula were performed. Exclusion criteria were visual acuity of less than 20/40, diseases other than glaucoma, and unreliable automated achromatic perimetry. Macular thickness measurements were generated using 6 radial optical coherence tomographic scans (5.9 mm) centered on the fovea, and mean and quadrantic macular thickness values were calculated. Results Fifty-nine eyes of 59 patients (29 normal and 30 glaucomatous) were enrolled (mean ± SD age, 56.7 ± 20.3 years; range, 20-91 years). All eyes with glaucoma had associated visual field loss (mean ± SD mean defect, −8.4 ± 5.8 d B). Mean macular thickness was significantly associated with visual field mean defect ( R 2 = 0.47; P R 2 = 0.32; P R 2 = 0.38; P P = .005) than in the unaffected quadrant (286± 27 µm). Mean RNFL thickness in the affected quadrant (89 ± 53 µm) was significantly thinner ( P = .009) than in the unaffected quadrant (121 ± 39 µm). Main Outcome Measures Mean total and quadrantic macular and RNFL thickness measurements. Conclusions Macular thickness changes are well correlated with changes in visual function and RNFL structure in glaucoma and may be a surrogate indicator of retinal ganglion cell loss.
TL;DR: Real-time acquisition, processing, and display of tissue structure, birefringence, and blood flow in a multi-functional optical coherence tomography (MF-OCT) system is demonstrated without dedicated hardware or extensive modification to the high-speed fiber-based OCT system.
Abstract: We demonstrate real-time acquisition, processing, and display of tissue structure, birefringence, and blood flow in a multi-functional optical coherence tomography (MF-OCT) system. This is accomplished by efficient data processing of the phase-resolved inteference patterns without dedicated hardware or extensive modification to the high-speed fiber-based OCT system. The system acquires images of 2048 depth scans per second, covering an area of 5 mm in width×1.2 mm in depth with real-time display updating images in a rolling manner 32 times each second. We present a video of the system display as images from the proximal nail fold of a human volunteer are taken.
TL;DR: A novel class of optical contrast agent is introduced, namely, encapsulating microspheres that are based not on fluorescence but on scattering nanoparticles within the shell or core, that are suitable for reflection- or scattering-based techniques such as optical coherence tomography, light microscopy, and reflectance confocal microscopy.
Abstract: Contrast agents are utilized in virtually every imaging modality to enhance diagnostic capabilities. We introduce a novel class of optical contrast agent, namely, encapsulating microspheres, that are based not on f luorescence but on scattering nanoparticles within the shell or core. The agents are suitable for ref lectionor scattering-based techniques such as optical coherence tomography, light microscopy, and ref lectance confocal microscopy. We characterize the optical properties of gold-, melanin-, and carbon-shelled contrast agents and demonstrate enhancement of optical coherence tomography imaging after intravenous injection of such an agent into a mouse. © 2003 Optical Society of America OCIS codes: 170.4500, 160.4760, 170.4580. When one is imaging biological tissues, it is often desirable to enhance the signals measured from specific structures. Contrast agents that produce specific image signatures have been utilized in virtually every imaging modality, including ultrasound, 1 computed tomography, 2 magnetic resonance imaging, 3 and optical microscopy. 4 Optical coherence tomography (OCT) is an emerging imaging technology that has found application in a wide range of biological and medical applications. 5 In this Letter we characterize and demonstrate a new class of optical contrast agent suitable for ref lection- or scattering-based optical imaging techniques, namely, OCT but that also includes light and ref lectance confocal microscopy. These agents are biocompatible, 6 are suitable for in vivo use, and produce enhanced backscatter that is detectable in highly scattering tissue. These agents may be tailored to adhere to specific molecules, cells, or tissue types, and thus provide additional selectivity that can enhance the utility of OCT as an emerging diagnostic technique. OCT is capable of cellular-resolution imaging and may ultimately have a role in the early diagnosis
15 Nov 2003
TL;DR: An interferometer topology based on 3 x 3 fiber couplers that gives instantaneous access to the magnitude and phase of die interferometric signal is presented and its performance in heterodyne and homodyne detection with a broadband light source is demonstrated.
Abstract: We present an interferometer topology based on 3 x 3 fiber couplers that gives instantaneous access to the magnitude and phase of die interferometric signal. We demonstrate its performance in heterodyne and homodyne detection with a broadband light source.
TL;DR: This technique, which employs a pair of CCD cameras to detect the in-phase and quadrature components of the heterodyne signal simultaneously, offers the advantage of phase-drift suppression in interferometric measurement.
Abstract: A two-dimensional heterodyne detection technique based on the frequency-synchronous detection method [Jpn. J. Appl. Phys. 39, 1194 (2000)] is demonstrated for full-field optical coherence tomography. This technique, which employs a pair of CCD cameras to detect the in-phase and quadrature components of the heterodyne signal simultaneously, offers the advantage of phase-drift suppression in interferometric measurement. Horizontal cross-sectional images are acquired at the rate of 100 frames/s in a single longitudinal scan, with a depth interval of 6 microm, making the rapid reconstruction of three-dimensional images possible.
TL;DR: The results indicate that CDOCT provides laser Doppler information in addition to conventional optical coherence tomography, allowing the observation of blood flow dynamics simultaneous to imaging retinal structure.
Abstract: Background Color Doppler optical coherence tomography (CDOCT) combines laser Doppler velocimetry and optical coherence tomography for simultaneous micron-scale resolution cross-sectional imaging of tissue microstructure and blood flow. Recently, CDOCT was adapted to a slitlamp biomicroscope for imaging structure and blood flow in the human retina. Objective To demonstrate feasibility of CDOCT for imaging retinal hemodynamics. Design Enabling CDOCT to measure retinal blood flow pulsatility in humans. Setting Laboratory. Main Outcome Measures Time-resolved flow profiles and images of retinal blood flow dynamics for measurement of pulsatility within retinal vessels. Results Rapid sequences of images were acquired over selected vessels near the optic nerve head. From these images, retinal blood flow profiles were extracted and synchronized to an external reference obtained with a photoplethysmograph. Each profile was acquired in less than 10 milliseconds. Conclusions Our results indicate that CDOCT provides laser Doppler information in addition to conventional optical coherence tomography, allowing the observation of blood flow dynamics simultaneous to imaging retinal structure. CDOCT is a promising technology for research and clinical studies of retinal blood flow dynamics. Clinical Relevance Blood flow dynamics, such as pulsatility and autoregulation, have been shown to change throughout the progression of diabetic retinopathy and glaucoma. Enabling CDOCT to observe retinal dynamics improves its potential as a clinical diagnostic tool.
Patent•
23 Jul 2003
TL;DR: In this paper, an optical probe with a sheath, a flexible, bi-directionally rotatable optical tansmission system, and a viscous damping fluid is described.
Abstract: The invention relates to an optical probe (130) including a sheath; a flexible, bi-directionally rotatable optical tansmission system (10, 135, 137) positioned within the sheath (44); and a viscous damping fluid (140) located in the sheath. The optical transmission system is capable of transmitting, focussing and collecting lignt of a predetermined range of wavelengths. the sheath and the viscous damping fluid are transpatent to at least some of the wavelengths of that light. The index of refracion of the viscous fluid is typically chosen to remove the optical effects induces by propagation through said sheath. Optical probes having a diameter less than substantially 500 νm for use in scanning light from a long, highly flexible fiber (10) to a sample. In one embodiment the porbe includes a viscous damping fluid suitable to prevent non-uniform rotational distortion (NURD). Such probes are used in Optical Coherence Tomography (OCT) and other inerferometric imaging and ranging systems, as well as for delivery of other imaging modalities (e.g. fluorescence) or therapeutic optical sources.
TL;DR: Investigations showed that it was possible to eliminate the influence of depth dependent dispersion by water in tissue by choosing a light source with a center wavelength near 1.0 microm.
Abstract: The influence of depth dependent dispersion by the main component of biological tissues, water, on the resolution of OCT was studied. Investigations showed that it was possible to eliminate the influence of depth dependent dispersion by water in tissue by choosing a light source with a center wavelength near 1.0 microm. Ultrahigh resolution ophthalmic imaging was performed at this wavelength range with a microstructure fiber light source.
TL;DR: Real-time endoscopic optical coherence tomography imaging differentiated adenomas, hyperplastic polyps, and normal colon tissue and revealed loss of tissue organization and reduced light scattering of dysplasia.
TL;DR: Examination of structure-poor OCT images reveals that they frequently display a characteristic texture that is due to speckle, which shows that texture analysis of OCT images may be capable of differentiating tissue types without reliance on visible structures.
Abstract: Optical coherence tomography (OCT) acquires cross- sectional images of tissue by measuring back-reflected light. Images from in vivo OCT systems typically have a resolution of 10 to 15 mm, and are thus best suited for visualizing structures in the range of tens to hundreds of microns, such as tissue layers or glands. Many normal and abnormal tissues lack visible structures in this size range, so it may appear that OCT is unsuitable for identification of these tissues. However, examination of structure-poor OCT images reveals that they frequently display a characteristic texture that is due to speckle. We evaluated the application of statistical and spectral texture analysis techniques for differentiating tissue types based on the structural and speckle content in OCT images. Excellent correct classification rates were obtained when images had slight visual differences (mouse skin and fat, correct classification rates of 98.5 and 97.3%, respectively), and reasonable rates were obtained with nearly identical-appearing images (normal versus abnormal mouse lung, correct classification rates of 64.0 and 88.6%, respectively). This study shows that texture analysis of OCT images may be capable of differentiating tissue types
Patent•
11 Jun 2003TL;DR: In this paper, the authors proposed a method of optical imaging comprising providing a sample to be imaged, measuring and correcting aberrations associated with the sample using adaptive optics, and imaging the sample by optical coherence tomography.
Abstract: The invention provides a method of optical imaging comprising providing a sample to be imaged, measuring and correcting aberrations associated with the sample using adaptive optics, and imaging the sample by optical coherence tomography. The method can be used to image the fundus of a human eye to provide diagnostic information about retinal pathologies such as macular degeneration, retinitis pigmentosa, glaucoma, or diabetic retinopathy. The invention further provides an apparatus comprising an adaptive optics subsystem and a two-dimensional optical coherence tomography subsystem.