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    1. Dynamic optical coherence tomography of skin blood vessels – proposed terminology and practical guidelines

      Dynamic optical coherence tomography of skin blood vessels – proposed terminology and practical guidelines

      Background Dynamic optical coherence tomography (D-OCT) has recently been introduced in dermatology. In contrast to ‚Standard’ OCT imaging, which exclusively relies on the morphological analysis of the tissue, D-OCT allows the in-vivo visualisation of blood flow. Preliminary D-OCT data showed differences in the vascularisation of nevus to melanoma transition, suggesting that this technology may help to differentiate between benign and malignant lesions. Objective Several factors may influence the quality of D-OCT imaging. Therefore, standard operating procedures as well as a common terminology are required for better validation and comparison of the images. Methods Here we present practical guidelines for optimal ...

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    2. In vivo measurements of blood vessels’ distribution in non-melanoma skin cancer by dynamic optical coherence tomography — a new quantitative measure?

      In vivo measurements of blood vessels’ distribution in non-melanoma skin cancer by dynamic optical coherence tomography — a new quantitative measure?

      Background Skin biopsies only provide point-in-time data making longitudinal studies difficult. Using Dynamic optical coherence tomography (D-OCT) in vivo , non-invasive imaging of the microvasculature becomes possible. The current OCT literature is almost exclusively based on qualitative information but quantitative data may offer additional advantages, for example, by reducing observer variation. The objective of this study was to evaluate the in vivo superficial distribution of blood vessels, defined as the surface-to-first-vessel distance, in actinic keratosis, basal cell carcinoma, squamous cell carcinoma and normal skin. Methods D-OCT images of 52 histologically verified lesions and corresponding normal skin were included. The dataset consisted ...

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    3. Intraocular robotic interventional surgical system (IRISS): Mechanical design, evaluation, and master–slave manipulation

      Intraocular robotic interventional surgical system (IRISS): Mechanical design, evaluation, and master–slave manipulation

      Background: Since the advent of robotic-assisted surgery, the value of using robotic systems to assist in surgical procedures has been repeatedly demonstrated. However, existing technologies are unable to perform complete, multi-step procedures from start to finish. Many intraocular surgical steps continue to be manually performed. Methods: An intraocular robotic interventional surgical system (IRISS) capable of performing various intraocular surgical procedures was designed, fabricated, and evaluated. Methods were developed to evaluate the performance of the remote centers of motion (RCMs) using a stereo-camera setup and to assess the accuracy and precision of positioning the tool tip using an optical coherence tomography ...

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    4. OCT layered tomography of the cornea provides new insights on remodeling after photorefractive keratectomy

      OCT layered tomography of the cornea provides new insights on remodeling after photorefractive keratectomy

      OCT (optical coherence tomography) of corneal layers was generated to analyze the remodeling of the epithelium and stroma after photorefractive keratectomy (PRK). Myopic PRK was performed in 15 patients. One eye underwent manual scraping of epithelium while the other was treated with Epi clear. Epi clear allowed a gentler removal of the epithelium compared to manual scraping. Scheimpflug (Pentacam, OCULUS Optikgerate Gmbh, Wetzlar, Germany) and OCT (RTVue, Optovue Inc., Fremont, California, USA) scans of the cornea were performed before and after PRK (3 months). The OCT scanner and Pentacam acquired 8 and 25 radial 2-D scans of the cornea, respectively ...

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    5. K-distribution three-dimensional mapping of biological tissues in optical coherence tomography

      K-distribution three-dimensional mapping of biological tissues in optical coherence tomography

      Probability density function (PDF) analysis with K-distribution model of optical coherence tomography (OCT) intensity signals has previously yielded a good representation of the average number of scatterers in a coherence volume for microspheres-in-water systems, and has shown initial promise for biological tissue characterization. In this work, we extend these previous findings, based on single point M-mode or 2D slice analysis, to full 3D imaging maps of the shape parameter α of the K-distribution PDF. After selecting a suitably-sized 3D evaluation window, and verifying methodology in phantoms the resultant parametric α images obtained in different animal tissues (rat liver and brain) show new ...

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    6. Assessment of bioresorbable scaffold with a novel high-definition 60 MHz IVUS imaging system: Comparison with 40-MHz IVUS referenced to optical coherence tomography

      Assessment of bioresorbable scaffold with a novel high-definition 60 MHz IVUS imaging system: Comparison with 40-MHz IVUS referenced to optical coherence tomography

      Background In vivo assessment of bioresorbable scaffold (BRS) is of growing clinical interest. The novel 60MHz high-definition intravascular ultrasound (HD-IVUS) has been developed to overcome the limitations of conventional 40 MHz IVUS. This study aimed to evaluate the performance and limitations of 60 MHz HD-IVUS compared with 40 MHz IVUS with respect to polymeric-strut visualization, quantitative and qualitative analysis, and feasibility of high-speed pullback in the assessment of BRS. Methods and Results In a bench-test model, 361 struts were analyzed to evaluate the influence of ultrasound-beam angles and proximity of adjacent struts on IVUS visualization of BRS struts. Various settings ...

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    7. TiO2 Coated Fluoride Nanoparticles for Dental Multimodal Optical Imaging

      TiO2 Coated Fluoride Nanoparticles for Dental Multimodal Optical Imaging

      Core-shell nanostructures associated with photonics techniques have found innumerous applications in diagnostics and therapy. In this work, we introduce a novel core-shell nanostructure design that serves as a multimodal optical imaging contrast agent for dental adhesion evaluation. This nanostructure consists of a rare-earth doped (NaYF 4 :Yb 60%,Tm 0.5%)/NaYF 4 particle as the core (hexagonal prism, ~51 nm base side length), and the highly refractive TiO 2 material as the shell (~thickness of 15 nm). We show that the TiO 2 shell provides enhanced contrast for Optical Coherence Tomography (OCT), while the rare-earth doped core upconverts excitation ...

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    8. Depth-resolved multimodal imaging: Wavelength Modulated Spatially Offset Raman Spectroscopy with Optical Coherence Tomography

      Depth-resolved multimodal imaging: Wavelength Modulated Spatially Offset Raman Spectroscopy with Optical Coherence Tomography

      A major challenge in biophotonics is multimodal imaging to obtain both morphological and molecular information at depth. We demonstrate a hybrid approach integrating optical coherence tomography (OCT) with wavelength modulated spatially offset Raman spectroscopy (WM-SORS). With depth co-localization obtained from the OCT, we can penetrate 1.2mm deep into the strong scattering media (lard) to acquire up to a 14-fold enhancement of a Raman signal from a hidden target (Polystyrene) with a spatial offset. Our approach is capable of detecting both Raman and OCT signals for pharmaceutical particles embedded in turbid media and revealing the white matter at depth within ...

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    9. Shear-Induced Diffusion of Red Blood Cells Measured with Dynamic Light Scattering-Optical Coherence Tomography

      Shear-Induced Diffusion of Red Blood Cells Measured with Dynamic Light Scattering-Optical Coherence Tomography

      Quantitative measurements of intravascular microscopic dynamics, such as absolute blood flow velocity, shear stress, and the diffusion coefficient of red blood cells (RBCs), are fundamental to understanding the blood flow behavior within the microcirculation, and for understanding why diffuse correlation spectroscopy (DCS) measurements of blood flow are dominantly sensitive to the diffusive motion of RBCs. Dynamic Light Scattering-Optical Coherence Tomography (DLS-OCT) takes the advantages of using DLS to measure particle flow and diffusion within an OCT resolution-constrained 3D volume, enabling the simultaneous measurements of absolute RBC velocity and diffusion coefficient with high spatial resolution. In this work, we applied DLS-OCT ...

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    10. An automated framework to quantify areas of regional ischemia in retinal vascular diseases with OCT angiography

      An automated framework to quantify areas of regional ischemia in retinal vascular diseases with OCT angiography

      In this observational and cross-sectional study, capillary non perfusion (CNP) and vascular changes in branch retinal vein occlusion (BRVO, sample size (n) = 26) and choroidal neovascularization (CNV, n = 29) were evaluated. Subjects underwent imaging using Optical coherence tomography angiography (Angiovue™ OCTA , RTVue XR, Optovue Inc., Fremont, CA). Local fractal analysis was applied to the OCTA images of superficial, deep and choriocapillaries layer. CNP area (BRVO eyes) and vascular parameters were computed using local fractal based method. Sensitivity and specificity of vascular parameters was assessed with receiver operating characteristics (ROC) curve. Automated CNP area showed excellent agreement with manually quantified CNP ...

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      Mentions: Optovue
    11. Simultaneous measurements of lymphatic vessel contraction, flow and valve dynamics in multiple lymphangions using optical coherence tomography

      Simultaneous measurements of lymphatic vessel contraction, flow and valve dynamics in multiple lymphangions using optical coherence tomography

      Lymphatic dysfunction is involved in many diseases including lymphedema, hypertension, autoimmune responses, graft rejection, atherosclerosis, microbial infections, cancer and cancer metastasis. Expanding our knowledge of lymphatic system function can lead to a better understanding of these disease processes and improve treatment options. Here, optical coherence tomography (OCT) methods were used to reveal intraluminal valve dynamics in 3D, and measure lymph flow and vessel contraction simultaneously in three neighboring lymphangions of the afferent collecting lymphatic vessels to the popliteal lymph node in mice. Flow measurements were based on Doppler OCT techniques in combination with exogenous lymph labelling by Intralipid. Through these ...

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    12. High intensity focused ultrasound (HIFU) and phase-sensitive optical coherence tomography (PhS-OCT) for high resolution surface acoustic wave (SAW) elastography

      High intensity focused ultrasound (HIFU) and phase-sensitive optical coherence tomography (PhS-OCT) for high resolution surface acoustic wave (SAW) elastography

      Elastography has the ability of quantitatively evaluating the mechanical properties of soft tissue, thus is helpful for diagnosis and treatment monitoring for many diseases, e.g. skin diseases. Surface acoustic waves (SAWs) have been proven to be a non-invasive, non-destructive method for accurate characterization of tissue elastic properties. Current surface acoustic wave elastography using high energy laser pulse or mechanical shaker still have some problems. In order to improve SAW elastography in medical application, a new technique was proposed in this paper, which combines high intensity focused ultrasound (HIFU) as a SAWs impulse inducer and PhS-OCT as a SAWs detector ...

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    13. Culprit plaque characteristics in younger versus older patients with acute coronary syndromes: An optical coherence tomography study from the FORMIDABLE registry

      Culprit plaque characteristics in younger versus older patients with acute coronary syndromes: An optical coherence tomography study from the FORMIDABLE registry

      Objectives Culprit plaque characteristics in young patients who experience an Acute Coronary Syndrome (ACS) evaluated by OCT (Optical Coherence Tomography) have to be defined. The OCT-FORMIDABLE is a multicentre retrospective registry enrolling consecutive patients with ACS who performed OCT in 9 European centres. Methods Patients were divided in two groups according to age at presentation: juvenile-ACS (age ≤ 50 years) and not juvenile-ACS (age > 50 years). Primary end-point was the prevalence of plaque rupture (PR). Secondary end point was the prevalence of thin cap fibro atheroma (TCFA), fibrocalcific and fibrotic plaque. Results 285 patients were included, 71 (24.9%) in juvenile-ACS ...

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    14. Suction blister lesions and epithelialization monitored by optical coherence tomography

      Suction blister lesions and epithelialization monitored by optical coherence tomography

      Background/purpose Our objective was to assess epithelialization of suction blister lesions by optical coherence tomography (OCT) and benchmark it to histology using epidermal thickness (ET) as the primary outcome. Methods Thirty-two healthy volunteers were recruited to Study 1 and 2. One 10-mm suction blister was raised on each buttock, and the blister roof was excised. Lesions were covered with moisture-retaining dressing. In Study 1, the lesions were OCT-scanned on day 0 (D0), D2 and D4 and excised for histological examination. In Study 2, the progress of epithelialization and skin barrier function were monitored to D14. Results ET increased from ...

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      Mentions: Mette Mogensen
    15. Assessment of acquired mucociliary clearance defects using micro-optical coherence tomography

      Assessment of acquired mucociliary clearance defects using micro-optical coherence tomography

      Background Dehydration of airway surface liquid (ASL) disrupts normal mucociliary clearance (MCC) in sinonasal epithelium, which may lead to chronic rhinosinusitis (CRS). Abnormal chloride (Cl − ) transport is one such mechanism that contributes to this disorder and can be acquired secondary to environmental perturbations, such as hypoxia at the tissue surface. The objective of this study was to assess the technological feasibility of the novel micro-optical coherence tomography (μOCT) imaging technique for investigating acquired MCC defects in cultured human sinonasal epithelial (HSNE) cells. Methods Primary HSNE cell cultures were subjected to a 1% oxygen environment for 12 hours to induce acquired ...

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    16. Evaluating the impact of optical coherence tomography in diabetic retinopathy screening for an Aboriginal population

      Evaluating the impact of optical coherence tomography in diabetic retinopathy screening for an Aboriginal population

      Importance Optical Coherence Tomography (OCT) is used routinely in management of diabetic eye disease but has not been evaluated in Australian outreach settings for screening programs. Background To evaluate the use of OCT combined with a fundus camera compared to a fundus camera only in a telehealth diabetic retinopathy (DR) screening program for Aboriginal Australians. Design Retrospective comparative study. Participants Patients with diabetes at two Aboriginal Health Services. Methods An intervention group was studied in 2015 using a Topcon 3D OCT-1 Maestro combined OCT/ fundus camera. A control group was studied in 2014 using a DRS non-mydriatic fundus camera. Fundus ...

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    17. Optical coherence tomography predicts 4-year incident diabetic neuropathy

      Optical coherence tomography predicts 4-year incident diabetic neuropathy

      Purpose To examine the capability of optical coherence tomography-derived retinal thickness measures in detecting 4-year incident diabetic peripheral neuropathy (DPN). Methods 145 eyes of 145 participants with diabetes but no DPN at baseline were examined for incident DPN. HbA 1c levels, nephropathy, neuropathy (DPN), cardiovascular measures, and various retinal thickness measures were examined at baseline and after 4 years. Incidence of DPN was defined as newly developed DPN at follow-up. Baseline factors were assessed by univariate and a step-wise multiple logistic regression, and the predictors were examined for diagnostic capabilities. Results Of the 145 participants without DPN at baseline, 51 ...

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    18. Intra- and interobserver reproducibility of Bruch's membrane opening minimum rim width measurements with spectral domain optical coherence tomography

      Intra- and interobserver reproducibility of Bruch's membrane opening minimum rim width measurements with spectral domain optical coherence tomography

      Purpose To investigate the reproducibility of Bruch's membrane opening minimum rim width (BMO-MRW) and retinal nerve fibre layer thickness (RNFLT) measurements using spectral domain optical coherence tomography (SD-OCT). Additionally, to investigate the reproducibility of BMO area measurements and fovea to BMO centre (FoBMO) angle. Methods Participants were healthy subjects ( n = 30) and patients with glaucoma ( n = 26). One eye of each participant was scanned to obtain optic nerve head (24 radial B-scans) and peripapillary (one circular B-scan) images by three independent examiners. Additionally, one examiner imaged each participant three times on the same day. Intra- and interobserver reproducibilities were ...

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    19. Ratiometric analysis of optical coherence tomography–measured in vivo retinal layer thicknesses for the detection of early diabetic retinopathy

      Ratiometric analysis of optical coherence tomography–measured in vivo retinal layer thicknesses for the detection of early diabetic retinopathy

      Influence of diabetes mellitus (DM) and diabetic retinopathy (DR) on parafoveal retinal thicknesses and their ratios was evaluated. Six retinal layer boundaries were segmented from spectral-domain optical coherence tomography images using open-source software. Five study groups: (1) healthy control (HC) subjects, and subjects with (2) controlled DM, (3) uncontrolled DM, (4) controlled DR and (5) uncontrolled DR, were identified. The one-way analyses of variance (ANOVA) between adjacent study groups (i. e. 1 with 2, 2 with 3, etc) indicated differences in retinal thicknesses and ratios. Overall retinal thickness, ganglion cell layer (GCL) thickness, inner plexiform layer (IPL) thickness, and their ...

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    20. Catheter-based anatomic and functional assessment of coronary arteries in anomalous aortic origin of a coronary artery, myocardial bridges and Kawasaki disease

      Catheter-based anatomic and functional assessment of coronary arteries in anomalous aortic origin of a coronary artery, myocardial bridges and Kawasaki disease

      Most diagnostic testing in patients with anomalous aortic origins of coronary arteries, myocardial bridges, and coronary artery changes after Kawasaki disease are performed with the use of noninvasive techniques. In some cases, however, further diagnostic information is needed to guide the clinician in treating these patients. In such instances, cardiac catheterization with invasive anatomic and functional testing is an invaluable tool. Moreover, interventional treatment in the cardiac catheterization laboratory may be performed in a small subset of these patients. As the diagnosis of these conditions is now becoming more common, it is important for pediatric interventional cardiologists to be familiar ...

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    21. Measuring contact area in a sliding human finger-pad contact

      Measuring contact area in a sliding human finger-pad contact

      Background/Purpose The work outlined in this paper was aimed at achieving further understanding of skin frictional behaviour by investigating the contact area between human finger-pads and flat surfaces. Methods Both the static and the dynamic contact areas (in macro- and micro-scales) were measured using various techniques, including ink printing, optical coherence tomography (OCT) and Digital Image Correlation (DIC). Results In the studies of the static measurements using ink printing, the experimental results showed that the apparent and the real contact area increased with load following a piecewise linear correlation function for a finger-pad in contact with paper sheets. Comparisons ...

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    49-72 of 765 « 1 2 3 4 5 6 ... 30 31 32 »
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