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    1. Optical Coherence Tomography: OCT (Book Chapter)

      Optical Coherence Tomography: OCT (Book Chapter)

      Optical coherence tomography (OCT) allows to measure geometric features inside translucent objects such as organic materials or organic tissues. The principle is based on interferometry. Time-domain and Fourier-domain methods are applied to make visible differences in the refractive index profile of the measuring object. We present the set-up of OCT sensors and show examples of applications such as 3D-imaging of an eye, B-scans of blood vessels or thickness measurements of multi-layer polymer films.

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    2. Automated 3D segmentation of multiple surfaces with a shared hole: segmentation of the neural canal opening in SD-OCT volumes

      Automated 3D segmentation of multiple surfaces with a shared hole: segmentation of the neural canal opening in SD-OCT volumes

      The need to segment multiple interacting surfaces is a common problem in medical imaging and it is often assumed that such surfaces are continuous within the confines of the region of interest. However, in some application areas, the surfaces of interest may contain a shared hole in which the surfaces no longer exist and the exact location of the hole boundary is not known a priori . The boundary of the neural canal opening seen in spectral-domain optical coherence tomography volumes is an example of a “hole” embedded with multiple surrounding surfaces. Segmentation approaches that rely on finding the surfaces alone ...

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    3. Speckle Reduction in Optical Coherence Tomography by Image Registration and Matrix Completion

      Speckle Reduction in Optical Coherence Tomography by Image Registration and Matrix Completion

      Speckle noise is problematic in optical coherence tomography (OCT). With the fast scan rate, swept source OCT scans the same position in the retina for multiple times rapidly and computes an average image from the multiple scans for speckle reduction. However, the eye movement poses some challenges. In this paper, we propose a new method for speckle reduction from multiply-scanned OCT slices. The proposed method applies a preliminary speckle reduction on the OCT slices and then registers them using a global alignment followed by a local alignment based on fast iterative diamond search. After that, low rank matrix completion using ...

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    4. Fabrication method of ultra-small gradient-index fiber probe

      Fabrication method of ultra-small gradient-index fiber probe

      Fabrication method and device of ultra-small gradient-index (GRIN) fiber probe were investigated in order to explore the development of ultra-small probes for optical coherence tomography (OCT) imaging. The beam-expanding effect of no-core fiber (NCF) and the focusing properties of the GRIN fiber lens were analyzed based on the model of GRIN fiber probe consisting of single-mode fiber (SMF), NCF and GRIN fiber lens. A stereo microscope based system was developed to fabricate the GRIN fiber probe. A fiber fusion splicer and an ultrasonic cleaver were used to weld and cut the fiber respectively. A confocal microscopy was used to measure ...

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    5. Evolution of vitreomacular adhesion to acute vitreofoveal separation with special emphasis on a traction-induced foveal pathology. A prospective study of spectral-domain optical coherence tomography

      Evolution of vitreomacular adhesion to acute vitreofoveal separation with special emphasis on a traction-induced foveal pathology. A prospective study of spectral-domain optical coherence tomography

      Purpose To investigate the evolution of vitreomacular adhesion (VMA) to acute vitreofoveal separation with particular emphasis on cases involving the underlying fovea. Methods In this observational case series, of 192 cases in the VMA stage, 51 progressed to acute vitreofoveal separation; this subgroup was divided into those with normal separation (Group I) and those with co-existing macular findings (Group II). All patients were examined using spectral domain-optical coherence tomography (SD-OCT) at regular three-month intervals. We recorded the best-corrected visual acuity (BCVA), the vitreomacular angle of the VMA (nasally and temporally), the horizontal diameter of the VMA, the macular thickness, the ...

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    6. Diagnosis of subretinal neovascularization associated with idiopathic juxtafoveal retinal telangiectasia — fluorescein angiography versus spectral-domain optical coherence tomography — can we choose?

      Diagnosis of subretinal neovascularization associated with idiopathic juxtafoveal retinal telangiectasia — fluorescein angiography versus spectral-domain optical coherence tomography — can we choose?

      Dear Editor We read with great interest the article entitled ”Diagnosis of subretinal neovascularization associated with idiopathic juxtafoveal retinal telangiectasia—fluorescein angiography versus spectral-domain optical coherence tomography by Chhablani J et al. [ 1 ]. This article compares the ability of fundus fluorescein angiography (FFA) and spectral-domain optical coherence tomography (SD-OCT) to diagnose subretinal neovascularization (SRNV) secondary to idiopathic juxtafoveal retinal telangiectasia (IJRT) type 2A, and also highlights the pitfalls of FFA and OCT in detecting and confirming SRNV in cases of IJRT type 2. However we have made the following observations

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    7. Comparison of morphologic findings obtained by optical coherence tomography in acute coronary syndrome caused by vasospasm and chronic stable variant angina

      Comparison of morphologic findings obtained by optical coherence tomography in acute coronary syndrome caused by vasospasm and chronic stable variant angina

      This study used optical coherence tomography (OCT) to evaluate morphologic changes in vasospastic lesions, which can cause acute coronary syndrome (ACS) or chronic stable VA. Thirty-nine patients (52.4 ± 9.0 years, 33 males) with vasospasm-induced ACS who presented with chest pain and displayed transient ST segment elevation on electrocardiography were included in the ACS group. Forty-one patients (49.3 ± 7.7 years, 33 males) who presented with chronic stable variant angina were included in the VA group. The clinical characteristics and morphologic OCT results of the two groups were compared. There were no differences in baseline characteristics, including the ...

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    8. Optical Coherence Tomography and Cryosurgery (Book Chapter)

      Optical Coherence Tomography and Cryosurgery (Book Chapter)

      Optical coherence tomography (OCT) provides real-time, cross-sectional skin images to a depth of up to 2 mm. OCT is a convenient and fast imaging technology that can be used bedside. In dermatology, the pretherapeutic delineation of both actinic keratoses (AK) and keratinocyte carcinomas has been a natural focus for applied OCT research, and more recently OCT research has turned on non-invasive monitoring of treatments. Previous studies have found good agreement between OCT images and histopathological images. Cryotherapy is a fast and easy treatment modality frequently used for the treatment of AK lesions in everyday dermatology practise. Cryosurgery with liquid nitrogen ...

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    9. Frequency and predictors of thrombus inside the guiding catheter during interventional procedures: an optical coherence tomography study

      Frequency and predictors of thrombus inside the guiding catheter during interventional procedures: an optical coherence tomography study

      Optical coherence tomography (OCT) is able to identify thrombus. We detect the frequency of thrombus inside the guiding catheter by OCT and its relationship with clinical and procedural factors. We screened 77 patients who underwent OCT pullbacks. Only patients with visible guiding catheter were finally included (35) and divided into thrombus (21) or no-thrombus group (14). Patients within thrombus group were mostly males (100 vs. 71 %, p = 0.05), with acute coronary syndrome (76 vs. 36 %, p = 0.02) and received more frequently percutaneous coronary intervention (86 vs. 43 %, p = 0.01) as compared to other group. A second dose ...

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    10. A comparison of tissue prolapse with optical coherence tomography and intravascular ultrasound after drug-eluting stent implantation

      A comparison of tissue prolapse with optical coherence tomography and intravascular ultrasound after drug-eluting stent implantation

      The aim of this study was to compare the detection rate of tissue prolapse (TP) in optical coherence tomography (OCT) and intravascular ultrasound (IVUS) after drug-eluting stent (DES) implantation and evaluate clinical implication of TP at 2 years after percutaneous coronary intervention. In spite of the superiority of OCT in the aspect of resolution when it was compared to IVUS, there was little data about the superiority of OCT in detecting TP. And there has been controversy about the clinical significance of TP. We enrolled 38 patients who treated with DES implantation. OCT and IVUS measurements were performed in stented ...

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    11. In Situ Circular Compression and Doppler Optical Coherence Tomography Studies on Effects of Diabetic Mellitus on Vesa Nervonum of Sciatic Nerve

      In Situ Circular Compression and Doppler Optical Coherence Tomography Studies on Effects of Diabetic Mellitus on Vesa Nervonum of Sciatic Nerve

      Diabetes mellitus is one of the most common diseases in the world and can causemany types of neuropathies, and even mortality. It is therefore important to understand how diabetes mellitus alters the mechanical properties of nerve tissues and their blood vessels. In this study, in situ compression-and-hold circular compression tests were applied to the sciatic nerves of both diabetic rats and normal rats. Doppler optical coherence tomography ( Doppler OCT ) was then utilized to monitor the configuration of the arterioles in two groups of rats. The force data acquired in the compression tests were fitted by using Fung’s quasi-linear viscoelastic ...

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    12. Associations of macular thickness in spectral-domain OCT with ocular and systemic cardiovascular parameters - The MIPH Eye & Health Study

      Associations of macular thickness in spectral-domain OCT with ocular and systemic cardiovascular parameters - The MIPH Eye & Health Study

      Purpose Beyond in-vivo histological analysis of retinal tissue, optical coherence tomography (OCT) allows quantitative image analysis. This study evaluates associations of macular retinal thickness measured with spectral-domain OCT (SD-OCT) and ocular and systemic cardiovascular parameters in adult subjects. Methods An epidemiological cross-sectional study was performed in the staff of a European high-tech company. Examination of known cardiovascular risk factors including biochemical blood analysis was performed, and ocular parameters such as refraction, tonometry, SD-OCT imaging of the macula and cornea, and fundus photography were evaluated. Retinal thickness measurements were evaluated according to the ETDRS grid. Associations of macular retinal thickness and ...

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    13. Probing regional mechanical properties of embryonic tissue using microindentation and optical coherence tomography

      Probing regional mechanical properties of embryonic tissue using microindentation and optical coherence tomography

      Physical forces regulate morphogenetic movements and the mechanical properties of embryonic tissues during development. Such quantities are closely interrelated, as increases in material stiffness can limit force-induced deformations and vice versa. Here we present a minimally invasive method to quantify spatiotemporal changes in mechanical properties during morphogenesis. Regional stiffness is measured using microindentation, while displacement and strain distributions near the indenter are computed from the motion of tissue labels tracked from 3-D optical coherence tomography (OCT) images. Applied forces, displacements, and strain distributions are then used in conjunction with finite-element models to estimate regional material properties. This method is applicable ...

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    14. Hemodynamic Flow Visualization of Early Embryonic Great Vessels Using μPIV

      Hemodynamic Flow Visualization of Early Embryonic Great Vessels Using μPIV

      Microparticle image velocimetry (μPIV) is an evolving quantitative methodology to closely and accurately monitor the cardiac flow dynamics and mechanotransduction during vascular morphogenesis. While PIV technique has a long history, contemporary developments in advanced microscopy have significantly expanded its power. This chapter includes three new methods for μPIV acquisition in selected embryonic structures achieved through advanced optical imaging: (1) high-speed confocal scanning of transgenic zebrafish embryos, where the transgenic erythrocytes act as the tracing particles; (2) microinjection of artificial seeding particles in chick embryos visualized with stereomicroscopy; and (3) real-time, time-resolved optical coherence tomography acquisition of vitelline vessel flow profiles ...

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    15. Recent Trends in Multimodal Optical Coherence Tomography. II. The Correlation-Stability Approach in OCT Elastography and Methods for Visualization of Microcirculation

      Recent Trends in Multimodal Optical Coherence Tomography. II. The Correlation-Stability Approach in OCT Elastography and Methods for Visualization of Microcirculation

      The second part of this paper continues the discussion of possibilities for combining functionally different types of biomedical characterization of tissues using optical coherence tomography (OCT). In the first part, polarization-sensitive imaging and conventional approaches to elastographic mapping in OCT were considered. Here, we consider an unconventional approach to elastographic mapping based on the analysis of variability of OCT images of the deformed tissue, omitting the stage of the displacement-field reconstruction. We also discuss methods for quantification of blood flow and visualization of microvasculature, some of which have much in common with the elastographic approach based on the analysis of ...

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    16. Novel insights provided by spectral-domain coherent tomography in pediatric ophthalmology

      Novel insights provided by spectral-domain coherent tomography in pediatric ophthalmology

      Tilted disk syndrome (TDS) is observed in approximately 1 % to 2 % of the population. This percentage appears to be highly variable according to the clinical and imaging features retained for establishing the accurate diagnosis. It is of paramount importance to distinguish isolated tilted optic disk from TDS. This syndrome has a number of alternative nomenclatures such as the nasal fundus ectasia syndrome, inversion of the optic disk, inverse myopia, and dysversion of the optic disk. TDS may be a variant of colobomatous defects. The definition of TDS has often been inaccurate in many studies which did not take account of ...

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    17. Optical coherence tomography in the diagnosis of basal cell carcinoma

      Optical coherence tomography in the diagnosis of basal cell carcinoma

      Since its introduction in dermatology in the late 1990s optical coherence tomography (OCT) has been used to study many skin diseases, in particular non-melanoma skin cancer and it s precursors. Special attention has been paid to superficial basal cell carcinoma (BCC), and a number of smaller observational studies have been published. The diagnostic criteria for BCC of these studies are systematically reviewed. A systemic review of English language studies was performed using PubMed, Google Scholar and Royal Danish Library, to search for primary papers on OCT and BCC. The references of retrieved papers were searched by hand for further relevant ...

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    18. Study of cystoid macular edema by optical coherent tomography following uneventful cataract surgery

      Study of cystoid macular edema by optical coherent tomography following uneventful cataract surgery

      The objective of this paper is to study the incidence of cystoid macular edema (CME) using optical coherence tomography (OCT) following uneventful small incision cataract surgery (SICS) and phacoemulsification. This was a descriptive, prospective study where 200 patients undergoing cataract surgery were randomly divided into two groups over a period of 1 year. Patients undergoing uneventful small incision cataract surgery were included in group I and patient undergoing uneventful phacoemulsification were included in group II, with 100 patients in each group. Preoperative assessment included best corrected visual acuity, detailed anterior segment and posterior segment evaluation, and intraocular pressure measurement. Macular ...

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    19. Fluorescein angiography versus spectral domain optical coherence tomography in idiopathic juxtafoveal retinal telangiectasia

      Fluorescein angiography versus spectral domain optical coherence tomography in idiopathic juxtafoveal retinal telangiectasia

      Dear Editor, We thank Dr. Singh and colleagues for their interest in our article, titled “Diagnosis of subretinal neovascularization associated with idiopathic juxtafoveal retinal telangiectasia—fluorescein angiography versus spectral-domain optical coherence tomography” [ 1 ]. We appreciate their concerns and here are the point-to-point responses to their comments. Comment 1. Color fundus photo has low sensitivity in detecting SRNV secondary to IJRT type 2A. This implies that a number of SRNV would be missed on color fundus photos. However, in this study, a color fundus photo is being used as a reference for presence or absence of SRNV, and this would result ...

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    20. Differentiating allergic and irritant contact dermatitis by high-definition optical coherence tomography: a pilot study

      Differentiating allergic and irritant contact dermatitis by high-definition optical coherence tomography: a pilot study

      Differentiation of allergic contact dermatitis (ACD) and irritant contact dermatitis (ICD) is important because of different management requirements. Various non-invasive tests have been used in an attempt to improve diagnosis. In irritant dermatitis, thickening of the epidermis has been a constant finding. High-Definition Optical Coherence Tomography (HD-OCT) is a non-invasive real-time three-dimensional imaging technique with cellular resolution for which an adapted algorithmic method for pattern analysis discriminating inflammatory skin diseases has been proposed. The aim of this study was threefold. (1) To evaluate the correlation between HD-OCT features and clinical scores of allergic and irritant patch test reactions. (2) To ...

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    21. Measurement of retinal nerve fiber layer and macular ganglion cell-inner plexiform layer with spectral-domain optical coherence tomography in patients with optic nerve head drusen

      Measurement of retinal nerve fiber layer and macular ganglion cell-inner plexiform layer with spectral-domain optical coherence tomography in patients with optic nerve head drusen

      Purpose To evaluate the effect of optic nerve head drusen (ONHD) on the retinal nerve fiber layer (RNFL) and macular ganglion cell–inner plexiform layer (GCIPL) using Cirrus optical coherence tomography (OCT). Methods Fifty-seven eyes of thirty patients with ONHD and thirty-eight eyes of twenty age-matched and sex-matched control subjects underwent circumpapillary and macular scanning using Cirrus OCT. The percentages of eyes with abnormal GCIPL and RNFL values according to the Cirrus normative data were analysed and compared. Results Overall, eyes with ONHD showed abnormally reduced values for average and minimum GCIPL thicknesses in 35 % and 45 % of cases compared ...

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    22. Retinal vessel diameter measurements by spectral domain optical coherence tomography

      Retinal vessel diameter measurements by spectral domain optical coherence tomography

      Purpose To describe a spectral domain optical coherence (OCT)-assisted method of measuring retinal vessel diameters. Methods All Patients with an OCT circle scan centered at the optic nerve head using a Spectralis OCT (Heidelberg Engineering, Heidelberg, Germany) were retrospectively reviewed. Individual retinal vessels were identified on infrared reflectance (IR) images and given unique labels both on IR and spectral domain OCT (SD-OCT). Vessel width and vessel types obtained by IR were documented as ground truth. From OCT, measurements of each vessel, including horizontal vessel contour diameter, vertical vessel contour diameter, horizontal hyperreflective core diameter, and reflectance shadowing width, were ...

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    23. Correlation between optical coherence tomography-derived intraluminal parameters and fractional flow reserve measurements in intermediate grade coronary lesions

      Correlation between optical coherence tomography-derived intraluminal parameters and fractional flow reserve measurements in intermediate grade coronary lesions

      Background Fractional flow reserve (FFR) measurements accurately assess functional relevance in intermediate grade coronary lesions. A significant relationship between hemodynamic stenosis severity and optical coherence tomography (OCT)-derived intraluminal dimensions has recently been demonstrated. However, morphologic thresholds to identify significant stenoses are variable and exploration of this correlation in patients with diabetes mellitus (DM) remains currently incomplete. This study aimed at comparing the diagnostic value of intraluminal parameters as determined by OCT to predict FFR ≤0.8 in lesions of patients with versus without DM. Methods In 100 patients (DM = 56, non-DM = 44) with 142 coronary de novo lesions (DM ...

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    24. Early axonal damage detection by ganglion cell complex analysis with optical coherence tomography in nonarteritic anterior ischaemic optic neuropathy

      Early axonal damage detection by ganglion cell complex analysis with optical coherence tomography in nonarteritic anterior ischaemic optic neuropathy

      Purpose To investigate the ability of ganglion cell complex (GCC) analysis by optical coherence tomography (OCT) to detect early axonal damage in nonarteritic anterior ischaemic optic neuropathy (NAION), and to assess the relationship of GCC measurements with visual field defects and function parameters. Methods Twenty-two patients with NAION participated in this retrospective case-series study. Patients underwent spectral-domain OCT measurement of retinal nerve fibre layer (RNFL) and GCC average and minimum thicknesses, best-corrected visual acuity, Ishihara test and Humphrey visual field (SITA Standard 24–2). These measurements were recorded in the acute (2–6 weeks after the ischaemic episode) and chronic ...

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    1-24 of 207 1 2 3 4 5 6 7 8 9 »
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