Topic
Optical coherence tomography
About: Optical coherence tomography is a research topic. Over the lifetime, 19051 publications have been published within this topic receiving 477433 citations. The topic is also known as: optical coherent tomography.
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TL;DR: In this article, an optical reflectometry (OR) technique with spectral interferometry (SIOR) was proposed for noninvasive in vivo measurements of the structure of the skin and the nail of an index finger.
Abstract: I present an optical reflectometry (OR) technique with spectral interferometry (SIOR) that realizes high dynamic range compared with a conventional OR system using the delayed heterodyne technique (DHOR), and report on the application of this system to noninvasive in vivo measurements of the structure of the skin and the nail of an index finger. The theoretically derived dynamic range of SIOR is m/4-times superior to that of DHOR, where m is the number of independent image pixels. A dynamic range of 105 db was experimentally realized, which is comparable to the theoretically expected dynamic range of 112 db.
157 citations
TL;DR: The presented technique has the potential to unveil photoreceptor development and pathogenesis as well as improved therapy monitoring of numerous retinal diseases.
Abstract: Cellular in vivo visualization of the three dimensional architecture of individual human foveal cone photoreceptors is demonstrated by combining ultrahigh resolution optical coherence tomography and a novel adaptive optics modality. Isotropic resolution in the order of 2-3µm, estimated from comparison with histology, is accomplished by employing an ultrabroad bandwidth Titanium:sapphire laser with 140nm bandwidth and previous correction of chromatic and monochromatic ocular aberrations. The latter, referred to as pancorrection, is enabled by the simultaneous use of a specially designed lens and an electromagnetically driven deformable mirror with unprecedented stroke for correcting chromatic and monochromatic aberrations, respectively. The increase in imaging resolution allows for resolving structural details of distal elements of individual foveal cones: inner segment zones - myoids and ellipsoids - are differentiated from outer segments protruding into pigment epithelial processes in the retina. The presented technique has the potential to unveil photoreceptor development and pathogenesis as well as improved therapy monitoring of numerous retinal diseases.
157 citations
TL;DR: Focal choroidal excavation is a newly described idiopathic entity in eyes having 1 or more focal areas of choroid excavation and in some patients, there may be an association with central serous chorioretinopathy.
Abstract: Objective To describe the clinical and imaging findings in patients with focal choroidal excavation. Methods Retrospective observational case series. The medical records of 12 patients (13 eyes) with focal choroidal excavation were reviewed. Clinical histories and imaging findings (including color photography, fundus autofluorescence imaging, fluorescein angiography, indocyanine green angiography, spectral-domain optical coherence tomography, and enhanced depth imaging spectral-domain optical coherence tomography) were analyzed. Results The mean age of the patients was 45 years (range, 22-62 years). Four patients were Asian. Mean visual acuity was 20/31 (range, 20/20 to 20/100). Mean refractive error was −3.54 diopters (D) (range, 6.00 to −8.00 D). One patient had bilateral involvement. All patients manifested varying degrees of foveal pigmentary changes that were usually hypoautofluorescent on fundus autofluorescence images. Fluorescein angiographic findings varied with degree of retinal pigment epithelial alterations. Indocyanine green angiography revealed relative hypofluorescence. In 7 eyes, spectral-domain optical coherence tomography revealed outer retinal layers conforming to retinal pigment epithelial alterations within the excavation. In the other 6 eyes, spectral-domain optical coherence tomography revealed a separation between the outer retina and the retinal pigment epithelium within the excavation. In 7 eyes studied with enhanced depth imaging spectral-domain optical coherence tomography, there was no evidence of scleral ectasia. Mean choroidal thickness of the uninvolved choroid was thicker than normal at 319 μm (range, 244-439 μm). All lesions remained stable except for in 1 eye, which had findings of central serous chorioretinopathy and secondary type 2 (subretinal) neovascularization. Conclusion Focal choroidal excavation is a newly described idiopathic entity in eyes having 1 or more focal areas of choroidal excavation. In some patients, there may be an association with central serous chorioretinopathy. Although most lesions remain stable, secondary choroidal neovascularization may occur.
157 citations
TL;DR: It is demonstrated that in vivo OCT imaging of normal coronary arteries, intimal dissections, and deployed stents is feasible, and allows identification of clinically relevant coronary artery morphology with high-resolution and contrast.
Abstract: Objective - A high-resolution coronary artery imaging modality has the potential to address important diagnostic and management problems in cardiology. Optical coherence tomography (OCT) is a promising new optical imaging technique with a resolution of approximately 10 μm. The purpose of this study was to use a new OCT catheter to demonstrate the feasibility of performing OCT imaging of normal coronary arteries, intimal dissections, and deployed stents in vivo. Methods and results - Normal coronary arteries, intimal dissections, and stents were imaged in five swine with OCT and compared with intravascular ultrasound (IVUS). In the normal coronary arteries, visualization of all of the layers of the vessel wall was achieved with a saline flush, including the intima which was not identified by IVUS. Following dissection, detailed layered structures including intimal flaps, intimal defects, and disruption of the medial wall were visualized by OCT. IVUS failed to show clear evidence of intimal and medial disruption. Finally, the microanatomic relationships between stents and the vessel walls were clearly identified only by OCT. Conclusions - In this preliminary experiment, we have demonstrated that in vivo OCT imaging of normal coronary arteries, intimal dissections, and deployed stents is feasible, and allows identification of clinically relevant coronary artery morphology with high-resolution and contrast.
156 citations
TL;DR: One of the main drawbacks of Fourier domain optical coherence tomography (FDOCT) is the limited measurement depth range, but phase shifting techniques allow reconstructing the complex sample signal resulting in a doubled depth range.
Abstract: One of the main drawbacks of Fourier domain optical coherence tomography (FDOCT) is the limited measurement depth range. Phase shifting techniques allow reconstructing the complex sample signal resulting in a doubled depth range. In current complex FDOCT realizations the phase shift is introduced via a reference path length modulation, which causes chromatic phase errors especially if broad bandwidth light sources are employed. With acousto-optic frequency shifters in the reference and sample arm, and the detector being locked to the resulting beating frequency, the signal is quadrature detected at high speed. The beating signal frequency is the same for all wavelengths allowing for achromatic complex reconstruction. With a Ti: Sapphire laser at 800 nm and spectral width of 130nm, a heterodyne complex FDOCT system is realized with 20kHz line rate and an axial resolution of 4μm.
156 citations