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    1. Motion Artefact Correction in Retinal Optical Coherence Tomography Using Local Symmetry

      Motion Artefact Correction in Retinal Optical Coherence Tomography Using Local Symmetry

      Patient movements during the acquisition of SD-OCT scans create substantial motion artefacts in the volumetric data that hinder registration and 3D analysis and can be mistaken for pathologies. In this paper we propose a method to correct these artefacts using a single volume scan while still retaining the overall shape of the retina. The method was quantitatively validated using a set of synthetic SD-OCT volumes and qualitatively by a group of trained OCT grading experts on 100 SD-OCT scans. Furthermore, we compared the motion compensation estimation by the proposed method with a hardware eye tracker on 100 SD-OCT volumes.

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    2. Comparison of event-based analysis of glaucoma progression assessed subjectively on visual fields and retinal nerve fibre layer attenuation measured by optical coherence tomography

      Comparison of event-based analysis of glaucoma progression assessed subjectively on visual fields and retinal nerve fibre layer attenuation measured by optical coherence tomography

      The purpose is to study the ability of an event-based analysis of retinal nerve fibre layer (RNFL) attenuation measured by Stratus ® optical coherence tomography (OCT) and to detect progression across the spectrum of glaucoma. Adult glaucoma suspects, ocular hypertensives and glaucoma patients who had undergone baseline RNFL thickness measurement on Stratus OCT and reliable automated visual field examination by Humphrey’s visual field analyser prior to March 2007 and had 5-year follow-up data were recruited. Progression on OCT was defined by two criteria: decrease in average RNFL thickness from baseline by at least 10 and 20 µ. Visual field progression was ...

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    3. Three-dimensional optic nerve head images using optical coherence tomography with a broad bandwidth, femtosecond, and mode-locked laser

      Three-dimensional optic nerve head images using optical coherence tomography with a broad bandwidth, femtosecond, and mode-locked laser

      Purpose The aim of this study was to demonstrate the fine laminar structure of the optic nerve head (ONH), in vivo, using a broad wavelength, ultra-high resolution, and optically coherent tomography (OCT) system. Methods This high-resolution OCT system, based on a 200 nm bandwidth spectrometer and an 8 femtosecond ultra-short, mode-locked, coherent laser light source, enabled in vivo cross-sectional ONH imaging with 2.0 μm axial resolution. A total of 300 optic disc B-scans, which consisted of 300 × 2048 pixels, were obtained in 10 μm steps. Three-dimensional images were rendered from these images to obtain n face images of the ...

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    4. Effect of optical clearing agents on optical coherence tomography images of cervical epithelium

      Effect of optical clearing agents on optical coherence tomography images of cervical epithelium

      Optical coherence tomography (OCT) can be used as an adjunct to colposcopy in order to detect precancerous and cancerous cervical lesions. Optical clearing agents (OCAs) temporarily reduce the optical scattering of biological tissues. The purpose of this study was to investigate their influence on OCT imaging. OCT images were taken from unsuspicious and suspicious areas of fresh conization specimens immediately after resection and 5, 10, and 20 min after application of dimethyl sulfoxide ( DMSO ) or polyethylene glycol (PEG). Corresponding histologies were obtained from all sites. The images taken 5, 10, and 20 min after application of OCA were compared to ...

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    5. Evaluation of filtering blebs exhibiting transconjunctival oozing using anterior segment optical coherence tomography

      Evaluation of filtering blebs exhibiting transconjunctival oozing using anterior segment optical coherence tomography

      Purpose To explore the features of filtering blebs exhibiting transconjunctival oozing via three-dimensional anterior segment optical coherence tomography (3D AS-OCT). Methods In this cross-sectional study, 131 eyes of 131 patients exhibiting filtering blebs were examined. Of those, 20 eyes were excluded as flat-shaped, non-functioning bleb. Transconjunctival oozing was defined as transconjunctival aqueous egress evident on the bleb surface, in the absence of any point leak observable using a slit-lamp, as confirmed by application of digital pressure. Total bleb height, the height of the fluid-filled cavity, and bleb wall thickness and density were measured using 3D AS-OCT. Patient age, the etiology ...

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    6. Optical coherence tomography and electrophysiological findings in torpedo maculopathy

      Optical coherence tomography and electrophysiological findings in torpedo maculopathy

      Purpose To describe the morphofunctional findings in a 6-year-old child with a unilateral lesion of the temporal macula called “torpedo maculopathy” throughout a 1-year follow-up. Methods Evaluation of retinal morphology and function was assessed by means of spectral-domain OCT scans, best-corrected visual acuity, full-field flash electroretinogram (ERG), multifocal electroretinogram (mfERG) and pattern visual evoked potentials (VEP). Patient was examined every 4 months for a 1-year follow-up time. Results Torpedo maculopathy consisted in a sharply demarcated hypopigmented oval iuxta-macular lesion (1.5 DD wide × 0.7 DD high). The baseline visual acuity of the affected eye was 20/25. OCT showed ...

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    7. Noninvasive Ocular Angiography by Optical Coherence Tomography (Book Chapter)

      Noninvasive Ocular Angiography by Optical Coherence Tomography (Book Chapter)

      Diabetic retinopathy, age-related macular degeneration, and glaucoma are all associated with impaired circulation. Noninvasive assessment of ocular circulation would be very powerful for understanding and diagnosing these eye diseases. Using high-speed optical coherence tomography (OCT), we developed a new OCT angiography algorithm called split-spectrum amplitude-decorrelation angiography (SSADA) for imaging ocular microcirculation. Here, the system and theory of this novel OCT angiography technique are reviewed; its capabilities for imaging retinal, choroidal, and optic nerve head blood flow are demonstrated; and its limitation is discussed.

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    8. Imaging of cardiovascular development in Mammalian embryos using optical coherence tomography (Book Chapter)

      Imaging of cardiovascular development in Mammalian embryos using optical coherence tomography (Book Chapter)

      The cardiovascular system is the first functional organ system to develop within the mammalian embryo. During the early stages of cardiovascular development, the heart and blood vessels undergo rapid growth and remodeling required for embryo viability, proper morphogenesis, and the function of all organ systems. Live imaging of these dynamic events in early mouse embryos is critical to understanding when and how these morphological changes occur during normal development and how mutations and pharmacological agents affect cardiovascular structure and function in vivo. The use of optical coherence tomography (OCT) allows for rapid, three-dimensional structural and functional imaging of mouse embryos ...

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    9. Identification and biometry of horizontal extraocular muscle tendons using optical coherence tomography

      Identification and biometry of horizontal extraocular muscle tendons using optical coherence tomography

      Purpose To purpose if this study was to determine whether the horizontal rectus muscle tendons (HRMTs) can be observed using anterior segment optical coherence tomography (AS-OCT) and to determine the repeatability of its measurements. Also, this study aimed to observe and measure the different external ocular structures at the level of the horizontal rectus muscle (HRM) insertion. Methods This was a retrospective, observational, descriptive and comparative study. Images were obtained utilizing the RTVue 100 CAM system. Eyes were analyzed at the three and nine o’clock position. Scans were performed for three different locations: the limbus, the ciliary body and ...

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    10. Optical Coherence Tomography to Assess Neurodegeneration in Multiple Sclerosis (Book Chapter)

      Optical Coherence Tomography to Assess Neurodegeneration in Multiple Sclerosis (Book Chapter)

      Retinal spectral domain optical coherence tomography (OCT) has emerged as a clinical and research tool in multiple sclerosis (MS) and optic neuritis (ON). This chapter summarizes a short OCT protocol as included in international consensus guidelines. The protocol was written for hands-on style such that both clinicians and OCT technicians can make use of it. The protocol is suitable for imaging of the optic nerve head and macular regions as a baseline for follow-up investigations, individual layer segmentation, and diagnostic assessment.

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    11. Intraoperative optical coherence tomography imaging to identify parathyroid glands

      Intraoperative optical coherence tomography imaging to identify parathyroid glands

      Objective Optical coherence tomography (OCT) is a non-invasive high-resolution imaging technique that permits characterization of microarchitectural features in real time. Previous ex vivo studies have shown that the technique is capable of distinguishing between parathyroid tissue, thyroid tissue, lymph nodes, and adipose tissue. The purpose of this study was to evaluate the practicality of OCT during open and minimally invasive parathyroid and thyroid surgery. Methods During parathyroid and thyroid surgery, OCT images were generated from parathyroid glands, thyroid tissue, lymph nodes, and adipose tissue. The images were immediately assessed by the operating team using the previously defined criteria. Second, the ...

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    12. Optical Coherence Tomography for Quantitative Diagnosis in Cardiovascular Disease (Book Chapter)

      Optical Coherence Tomography for Quantitative Diagnosis in Cardiovascular Disease (Book Chapter)

      In recent years, biomedical imaging technology has made rapid advances that enable the visualization, quantification, and monitoring of morphology and function. There are several tomography modalities which are currently used in clinics, such as computed tomography (CT), positron emission tomography (PET), magnetic resonance imaging (MRI), ultrasound (US), etc. These modalities have been developed for in vivo structural and functional imaging in humans, but frequently require large, expensive and complex systems. The penetration depth of these tomographic techniques is long, but the spatial resolution is typically on the order of several millimeters or hundred of micrometers.

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    13. Development of Tissue Characterization Using Optical Coherence Tomography for Defining Coronary Plaque Morphology and the Vascular Responses After Coronary Stent Implantation

      Development of Tissue Characterization Using Optical Coherence Tomography for Defining Coronary Plaque Morphology and the Vascular Responses After Coronary Stent Implantation

      Cardiovascular disease is associated with a high burden of mortality secondary to acute coronary events. Assessment for vulnerable plaque and an understanding of the etiology of stent failure by intravascular imaging may facilitate a greater understanding of the underlying processes responsible for adverse clinical outcomes and guide future therapy. This review focuses on the role of optical coherence tomography in tissue characterization and highlights future advances within the field providing potential enhancement of image interpretation.

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    14. Microscale imaging of cilia-driven fluid flow

      Microscale imaging of cilia-driven fluid flow

      Cilia-driven fluid flow is important for multiple processes in the body, including respiratory mucus clearance, gamete transport in the oviduct, right–left patterning in the embryonic node, and cerebrospinal fluid circulation. Multiple imaging techniques have been applied toward quantifying ciliary flow. Here, we review common velocimetry methods of quantifying fluid flow. We then discuss four important optical modalities, including light microscopy, epifluorescence, confocal microscopy, and optical coherence tomography, that have been used to investigate cilia-driven flow.

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    15. Optical Coherence Tomography for Prostate Cancer and Beyond (Book Chapter)

      Optical Coherence Tomography for Prostate Cancer and Beyond (Book Chapter)

      Since it was first used to evaluate human genitourinary tissue in 1997, OCT has emerged as a promising modality to provide real-time, high-resolution imaging of urologic organs. In the bladder, it has demonstrated a high sensitivity in identifying regions of the bladder suspicious for CIS and between invasive and noninvasive malignancy; it has been studied as an “optical biopsy” both during the initial cystoscopic diagnosis and intraoperatively in bladder-preserving surgery. Several small, ex vivo studies have shown promising results in the ability of OCT to demonstrate histopathologic alterations to renal morphology such as in renal ischemia and malignancy. It may ...

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    16. Optical Coherence Tomography in Bladder Cancer (Book Chapter)

      Optical Coherence Tomography in Bladder Cancer (Book Chapter)

      The current diagnostic standard for grading and staging of non-muscle-invasive bladder cancer (NMIBC) is based on the histopathology obtained during transurethral resection of the bladder tumour (TURBT) or biopsies. Although considered reference standard, this technique has some limitations: First, no real-time intraoperative histological information is obtained on stage and grade. Real-time intraoperative histological information could be helpful when NMIBC is treated by electric coagulation or laser ablation. The urologist has to rely on his/her judgement of stage and grade since no tissue is harvested for histological confirmation. In addition, in many centres, patients with a history of low-grade, non-invasive ...

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    17. Evaluation of IVOCT imaging of coronary artery metallic stents with neointimal coverage

      Evaluation of IVOCT imaging of coronary artery metallic stents with neointimal coverage

      Accuracy of IVOCT for measurement of neointimal thickness and effect of neointima in the appearance of metallic struts in IVOCT images was investigated. Phantom vessels were constructed and coronary stents were deployed and covered with thick (250–400 μm) and thin (30–70 μm) phantom neointima. High resolution Micro-CT images of the stent struts were recorded as a gold standard. IVOCT images of the phantom vessels were acquired with various luminal blood scattering strengths and measured neointimal thicknesses from IVOCT and Micro-CT images were compared. In transparent lumen, comparison of IVOCT and Micro-CT neointima thickness measurements found no significant difference ...

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    18. In vitro assessment of effects of hyperglycemia on the optical properties of blood during coagulation using optical coherence tomography

      In vitro assessment of effects of hyperglycemia on the optical properties of blood during coagulation using optical coherence tomography

      No published reports have demonstrated the capability of the optical coherence tomography technique for quantifying the optical coherence tomography signal slope, 1/e light penetration depth, and attenuation coefficient of hyperglycemic blood by an in vitro assessment. The purpose of this study was to investigate the effects of hyperglycemia on optical properties during in vitro blood coagulation by optical coherence tomography. Normal whole blood acted as the control group. After 1-h coagulation, the average optical coherence tomography signal slope decreased approximately 23.3 and 16.7 %, and the 1/e light penetration depths increased approximately 21.5 and 19.2 ...

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    19. Application of Improved Homogeneity Similarity-Based Denoising in Optical Coherence Tomography Retinal Images

      Application of Improved Homogeneity Similarity-Based Denoising in Optical Coherence Tomography Retinal Images

      Image denoising is a fundamental preprocessing step of image processing in many applications developed for optical coherence tomography (OCT) retinal imaging—a high-resolution modality for evaluating disease in the eye. To make a homogeneity similarity-based image denoising method more suitable for OCT image removal, we improve it by considering the noise and retinal characteristics of OCT images in two respects: (1) median filtering preprocessing is used to make the noise distribution of OCT images more suitable for patch-based methods; (2) a rectangle neighborhood and region restriction are adopted to accommodate the horizontal stretching of retinal structures when observed in OCT ...

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    20. Optical coherence tomography shows early loss of the inferior temporal quadrant retinal nerve fiber layer in autosomal dominant optic atrophy

      Optical coherence tomography shows early loss of the inferior temporal quadrant retinal nerve fiber layer in autosomal dominant optic atrophy

      Purpose The aim of the study was to evaluate the relationship between visual function and retinal nerve fiber layer thickness (RNFLT) determined using Stratus optical coherence tomography (OCT) in patients with autosomal dominant optic atrophy (ADOA). Methods The study was a retrospective, institutional, and comparative case series. Thirty-six consecutive patients with ADOA and 72 age-matched normal controls were compared with regard to RNFLT, best-corrected visual acuity (BCVA), and visual field. Results The relative reduction of RNFLT of ADOA patients was most evident in the temporal quadrant (56.8 %), followed by the inferior (35.5 %), superior (27.2 %), and nasal quadrants ...

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    21. Microanatomy of the tympanic membrane in chronic myringitis obtained with optical coherence tomography

      Microanatomy of the tympanic membrane in chronic myringitis obtained with optical coherence tomography

      A microscope-based optical coherence tomography (OCT) device was used to assess the microanatomy of the tympanic membrane in patients with chronic myringitis. A prospective study was designed for this purpose. OCT measurements of the tympanic membrane were done on 11 patients with myringitis with a microscope-based spectral domain OCT system. The in vivo findings were compared with those findings of a control group consisting of 36 patients with retraction pockets or atrophic tympanic membranes ( n = 13), myringosclerosis ( n = 12) and perforations ( n = 11). In active chronic myringitis, the thickness of the tympanic membrane is increased compared to healthy membranes and ...

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    22. The impact of multifocal intraocular lens in retinal imaging with optical coherence tomography

      The impact of multifocal intraocular lens in retinal imaging with optical coherence tomography

      Multifocal intraocular lenses (MF IOLs) have concentric optical zones with different dioptric power, enabling patients to have good visual acuity at multiple focal points. However, several optical limitations have been attributed to this particular design. The purpose of this study is to access the effect of MF IOLs design on the accuracy of retinal optical coherence tomography (OCT). Cross-sectional study conducted at the Refractive Surgery Department of Central Lisbon Hospital Center. Twenty-three eyes of 15 patients with a diffractive MF IOL and 27 eyes of 15 patients with an aspheric monofocal IOL were included in this study. All patients underwent ...

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    23. Innovations in Microscopic Imaging of Atherosclerosis and Valvular Disease (Book Chapter)

      Innovations in Microscopic Imaging of Atherosclerosis and Valvular Disease (Book Chapter)

      Calcific aortic valve disease (CAVD) is still an unsolved medical problem, because the pathogenesis of CAVD is poorly understood and early calcification is hard to identify. The lack of high-resolution imaging tools to study early stage disease further hampers the search for therapeutic targets. Micro-optical coherence tomography (μOCT), which is a new form of OCT, is the highest-resolution cross-sectional OCT technology available today with 1 μm resolution. We used μOCT to visualize detailed cellular and subcellular structure associated with early calcific changes in diseased human and murine aortic valves. The results suggest that μOCT imaging has the potential to provide ...

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    24. Difference in correspondence between visual field defect and inner macular layer thickness measured using three types of spectral-domain OCT instruments

      Difference in correspondence between visual field defect and inner macular layer thickness measured using three types of spectral-domain OCT instruments

      Purpose To compare the relationship between visual field sensitivity (VFS) and macular parameters measured using three spectral-domain optical coherence tomography (SD-OCT) instruments and to determine a base level (=floor effect) for macular parameters. Methods We imaged 127 glaucomatous eyes (1 eye per subject) using three different OCT instruments, i.e., the Cirrus , RTVue and 3D OCT devices; 76 normal eyes were evaluated as controls using the same instruments. The thicknesses of the macular retinal nerve fiber layer (mRNFL), ganglion cell layer+inner plexiform layer (GCL/IPL), and mRNFL+GCL/IPL (GCC) were analyzed. The VFS of the area analyzed by ...

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    1-24 of 237 1 2 3 4 5 6 7 8 9 10 »
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