1. 1-24 of 1328 1 2 3 4 ... 54 55 56 »
    1. Contactless mapping of ceramic green density using optical coherence tomography

      Contactless mapping of ceramic green density using optical coherence tomography

      We propose a contactless method for mapping the density distribution of green ceramics using optical coherence tomography (OCT). A correlation was found between the OCT signal and density of green alumina tablets. Using this relationship, proof-of-concept mapping of model samples produced reasonable results, suggesting that high-speed, contactless mapping of the ceramic green density with micrometer-scale resolution is possible, owing to the unique features of OCT. This technique may contribute to more efficient and eco-friendly ceramics production.

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    2. Identification of Organs Inside Hard Tick Body Using Spectral-domain Optical Coherence Tomography

      Identification of Organs Inside Hard Tick Body Using Spectral-domain Optical Coherence Tomography

      Ixodidae tick, also known as a hard tick, is one of the major vectors of various tick-borne diseases. Studying its anatomy is the fundamental approach for diverse acarological studies and the key to understanding tick morphology. However, the conventional methods of observing internal organs rely primarily on dissection, which damages specimens irrecoverably. In this study, we developed an optical coherence tomography (OCT) system to non-invasively investigate the morphological characteristics of the hard tick. Herein, OCT imaging was conducted by the developed spectral-domain OCT (SD-OCT) system with two different objective lenses. The developed system provides an axial resolution (in the air ...

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    3. Peripapillary Retinal Nerve Fiber Layer and Ganglion Cell-Inner Plexiform Layer Changes on Optical Coherence Tomography in Patients with Unilateral Hypertensive Cytomegalovirus Anterior Uveitis

      Peripapillary Retinal Nerve Fiber Layer and Ganglion Cell-Inner Plexiform Layer Changes on Optical Coherence Tomography in Patients with Unilateral Hypertensive Cytomegalovirus Anterior Uveitis

      Purpose: To investigate whether peripapillary retinal nerve fiber layer (pRNFL) and macular ganglion cell-inner plexiform layer (GCIPL) thinning are present in patients with unilateral hypertensive Cytomegalovirus anterior uveitis (hCMV AU). Methods: We included 19 eyes with unilateral hCMV AU and their unaffected fellow eyes as the control group in this study. Peripapillary RNFL and macular GCIPL changes were determined using spectral-domain (SD) - optical coherence tomography (OCT). Results: The overall calculated mean pRNFL thickness was significantly lower in the affected eyes with hCMV AU than in the unaffected fellow eyes (p = 0.012). The mean macular GCIPL thickness in the affected ...

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    4. Plexus-specific retinal vascular anatomy and pathologies as seen by projection-resolved optical coherence tomographic angiography

      Plexus-specific retinal vascular anatomy and pathologies as seen by projection-resolved optical coherence tomographic angiography

      Optical coherence tomographic angiography (OCTA) is a novel technology capable of imaging retinal vasculature three-dimensionally at capillary scale without the need to inject any extrinsic dye contrast. However, projection artifacts cause superficial retinal vascular patterns to be duplicated in deeper layers, thus interfering with the clean visualization of some retinal plexuses and vascular pathologies. Projection-resolved OCTA (PR-OCTA) uses post-processing algorithms to reduce projection artifacts. With PR-OCTA, it is now possible to resolve up to 4 distinct retinal vascular plexuses in the living human eye. The technology also allows us to detect and distinguish between various retinal and optic nerve diseases ...

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    5. Saline as an alternative to radio-contrast for optical coherence tomography guided percutaneous coronary intervention: A prospective comparison

      Saline as an alternative to radio-contrast for optical coherence tomography guided percutaneous coronary intervention: A prospective comparison

      Objectives: To do a quantitative comparison of saline and contrast Frequency domain optical coherence tomography (FD-OCT) during percutaneous coronary intervention (PCI) optimisation. Methods: 13 pairs of OCT runs were analysed, wherein each pair consisted of a contrast run and a heparinized saline run taken in the same coronary artery at the same position. Quantitative analysis was done comparing minimal lumen area (MLA), proximal reference diameter (PRD), distal reference diameter (DRD) and percentage area stenosis (AS) at the same anatomical location. Lesion morphologies, rendered stent view and 3D reconstruction were compared for image clarity. Result: The saline OCT runs resulted in ...

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    6. Imaging of Cardiac Transplantation: An Overview

      Heart transplantation (HTx) remains the optimal treatment for selected patients with end-stage advanced heart failure. However, survival is limited early by acute rejection and long term by cardiac allograft vasculopathy (CAV). Even though the diagnosis of rejection is based on histology, cardiac imaging provides a pivotal role for early detection and severity assessment of these hazards. The present review focuses on the use and reliability of different invasive and non-invasive imaging modalities to detect and monitor CAV and rejection after HTx. Coronary angiography remains the corner stone in routine CAV surveillance. However, angiograms are invasive and underestimates the CAV severity ...

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    7. Past, present and future role of retinal imaging in neurodegenerative disease

      Retinal imaging technology is rapidly advancing and can provide ever-increasing amounts of information about the structure, function and molecular composition of retinal tissue in humans in vivo . Most importantly, this information can be obtained rapidly, non-invasively and in many cases using Food and Drug Administration-approved devices that are commercially available. Technologies such as optical coherence tomography have dramatically changed our understanding of retinal disease and in many cases have significantly improved their clinical management. Since the retina is an extension of the brain and shares a common embryological origin with the central nervous system, there has also been intense interest ...

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    8. Assessment of colloidal NaGdF4:Er3+/Yb3+ upconversion phosphor as contrast enhancer for optical coherence tomography

      Assessment of colloidal NaGdF4:Er3+/Yb3+ upconversion phosphor as contrast enhancer for optical coherence tomography

      In-vitro imaging by swept-source optical coherence tomography (OCT) represents a class of advanced tomography that provides comprehensive and accurate clinical diagnostics. Here colloidal NaGdF 4 :Er 3+ /Yb 3+ particles having an average size of 32 nm were successfully synthesized by a facial thermal decomposition method and then used as a contrast agent in OCT imaging. Prepared phosphor has shown bright green upconversion emission under 976 nm diode laser. The phosphor particles had increased the scattering of OCT scanning radiation, and thus higher image contrast was observed. The results indicate that upconversion phosphors may work as suitable contrast agents for ...

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      Mentions: Raju Poddar
    9. Retinal nonperfusion in optical coherence tomography angiography

      Retinal nonperfusion in optical coherence tomography angiography

      Background: Retinal nonperfusion (NP) is a biomarker for assessment of the severity of diabetic retinopathy and retinal vein occlusion. However, various conditions mimic the retinal NP flow void signals that are observed in optical coherence tomography angiography (OCTA). Methods: In this review, the possible mechanisms for these similar void flow signals in OCTA were summarized, and the discrepancies between the evaluations of retinal NP with fluorescein angiography and OCTA were also investigated and evaluated in terms of size and morphology. Results and conclusion: Vascular occlusion, resulting in retinal ischemia, leads to a flow void signal, indicating retinal NP in OCTA ...

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    10. Detection and analysis of early degradation at resin-dentin interface by optical coherence tomography (OCT) and confocal laser scanning microscope (CLSM)

      Detection and analysis of early degradation at resin-dentin interface by optical coherence tomography (OCT) and confocal laser scanning microscope (CLSM)

      Objective To evaluate early degradation at resin-dentin interface using non-invasive swept-source optical coherence tomography (SS-OCT) and confocal laser scanning microscope (CLSM). Methods Self-etch adhesives and resin-composites containing bisphenol-glycidyl-dimethacrylate (Bis-GMA), which is one of the most widely used monomers in restorative materials, were investigated in this study. Forty cervical cavities were prepared in bovine incisors and applied by the adhesive with/without Bis-GMA (AdhesiveBG/Adhesive), filled by the resin with/without Bis-GMA (ResinBG/Resin) and then challenged by cariogenic biofilm (37 °C, 24 h). Gap Formation and dentin demineralization around resin-composites were observed by SS-OCT and CLSM. Results Three types of ...

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    11. Contribution of OCT angiography in angioid streaks

      Contribution of OCT angiography in angioid streaks

      Purpose: To study the appearance of angioid streaks (AS) in swept source optical coherence tomography angiography. Methods: Retrospective observational study of 16 patients (31 eyes) with various stages of AS. All included patients underwent complete ophthalmologic examinations including best-corrected visual acuity (BCVA), slit-lamp examination, indirect ophthalmoscopy and fundus photography. Swept source optical coherence tomography (SS-OCT), OCT angiography (OCT-A) and fluorescein angiography were also performed. Results: En face OCT detected hyper-reflective points in 65% of cases, with a choriocapillaris (CC) shadow on the corresponding OCT-A. Diffuse CC rarefaction was detected in 94%. In eyes without neovascular complications, streaks were visible as ...

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    12. Role of intravascular imaging for the diagnosis of recanalized coronary thrombus

      Role of intravascular imaging for the diagnosis of recanalized coronary thrombus

      Introduction Recanalized thrombus (RCT) of coronary arteries is frequently unrecognized in interventional cardiology practice. Intravascular imaging conclusively establishes its diagnosis, which otherwise is often misdiagnosed as fresh thrombus, spontaneous coronary artery dissection, or severe calcification based on angiography, alone. We hereby report our experience of 10 RCT patients, who had the intravascular imaging-guided diagnosis, followed by the successful percutaneous coronary intervention (PCI). Methods It was a retrospective analysis of 10 patients, who had angiographic haziness of the target lesion during PCI, which were found to be RCT on intravascular imaging. Either optical coherence tomography (OCT) or intravascular ultrasound (IVUS) was ...

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    13. Optical Coherence Tomography Angiography Findings in Patients with COVID-19: Abbreviated title: OCTA in COVID-19 patients

      Optical Coherence Tomography Angiography Findings in Patients with COVID-19: Abbreviated title: OCTA in COVID-19 patients

      Purpose: This study aimed to examine the changes in choriocapillaris and retina caused by COVID-19 by comparing optical coherence tomography angiography (OCTA) findings of COVID-19 patients and healthy controls. Methods: The study and control groups consisted of 54 eyes of 27 participants, each. Patients and controls underwent OCTA examination. Foveal zone vessel density and parafoveal zone vessel density (for four quadrants: nasal, temporal, superior, inferior) were calculated for both superficial and deep capillary plexuses. In addition, choriocapillaris flow and foveal avascular zone (FAZ) areas were calculated. Results: For the parafoveal area, in the study group, vessel density was significantly lower ...

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    14. Deposits on retinal surface seen on optical coherence tomography in ocular amyloidosis

      Deposits on retinal surface seen on optical coherence tomography in ocular amyloidosis

      Objective: To investigate the tomographic features in patients with hereditary amyloidosis transthyretin (hATTR). Design: Retrospective case series and analysis of B-scan optical coherence tomography (OCT) images. Participants: A total of 120 patients (240 eyes) diagnosed with hATTR. Methods: We performed a retrospective review of the treatment history and retrospective analysis of the OCT images of patients with hATTR. The parameters analyzed were the age at which the last OCT was performed, presence of ocular amyloidosis, history of pars plana vitrectomy (PPV), systemic treatment, and genetic mutations. Two independent evaluators evaluated the OCT images for characteristic needle-shaped pattern deposits on the ...

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    15. Polymerically engineered upconversion nanoparticles (UCNPs) as contrast agent for functionally modified optical coherence tomography (OCT)

      Polymerically engineered upconversion nanoparticles (UCNPs) as contrast agent for functionally modified optical coherence tomography (OCT)

      Upconversion nanoparticles (UCNPs) are widely recognized exogenous contrast agents for bioimaging. Swept source optical coherence tomography (SSOCT) is a non-invasive imaging tool commissioned for cross-sectional imaging of the biological sample. We present polymerically modified UCNPs as a potential contrast agent for SSOCT. In this communication, functionalized NaYF4: Ho3+/Yb3+ UCNPs were synthesized for more bioavailability with a coating of two different polymers namely, polyethylene glycol (PEG) and polyvinylpyrrolidone (PVP). Time-dependent diffusion dynamics of functionalized UCNPs were performed in-vivo with a mice model. Imaging was performed with both inactive and excited UCNPs. A separate optical system was developed ...

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    16. Analyzing Scaling Behavior of Calcium Sulfate in Membrane Distillation via Optical Coherence Tomography

      Analyzing Scaling Behavior of Calcium Sulfate in Membrane Distillation via Optical Coherence Tomography

      Deepening the understanding of scaling processes would facilitate the improvement of membrane distillation (MD) as a promising technique for sustainable development. This study investigated the scaling of calcium sulfate in MD via an approach based on optical coherence tomography (OCT). The OCT-based characterization enabled an analysis that correlated the flux decline with the morphological evolution of the scaling layer. It was revealed by this analysis that the reduction in the evaporation rate could be dominated by different mechanisms as the crystalline particles grew and deposited on the membrane surface; the striping phenomenon visualized by mapping the local growth rates provided ...

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    17. Automatic fluid segmentation in retinal optical coherence tomography images using attention based deep learning

      Automatic fluid segmentation in retinal optical coherence tomography images using attention based deep learning

      Optical coherence tomography (OCT) is one of the most commonly used ophthalmic diagnostic techniques. Macular Edema (ME) is the swelling of the macular region in the eye. Segmentation of the fluid region in the retinal layer is an important step in detecting lesions. However, manual segmentation is often a time consuming and subjective process. In this paper, an improved U-Net segmentation method is proposed. In this method, the attention mechanism is introduced to automatically locate the fluid region, which avoids the problem of excessive calculation in multi-stage methods. At the same time, the use of dense skip connections which combines ...

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    18. Sub-surface characterisation of latest-generation identification documents using optical coherence tomography

      Sub-surface characterisation of latest-generation identification documents using optical coherence tomography

      The identification of individuals, particularly at international border crossings, coupled with the evolving sophistication of identity documents are issues that authorities must contend with. Particularly, the ability to distinguish legitimate from counterfeit documents, with high throughput, sensitivity, and selectivity is an ever-evolving challenge. Over the last decade, an increasing number of security features have been introduced by authorities in identification documents. The latest generation of travel documents (such as passports and national ID cards) forego paper substrates for several layers of polycarbonate, allowing security features to be embedded within the documents. These security features may contain information at either the ...

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    19. In-vivo imaging for assessing tumor growth in mouse models of ocular melanoma

      In-vivo imaging for assessing tumor growth in mouse models of ocular melanoma

      Uveal melanoma (UM) and conjunctival melanoma (CM) are ocular malignancies that give rise to life-threatening metastases. Although local disease can often be treated successfully, it is often associated with significant vision impairment and treatments are often not effective against metastatic disease. Novel treatment modalities that preserve vision may enable elimination of small tumors and may prevent subsequent metastatic spread. Very few mouse models of metastatic CM and UM are available for research and for development of novel therapies. One of the challenges is to follow tumor growth in-vivo and to determine the right size for treatment, mainly of the posterior ...

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    20. Effect of blunt ocular trauma on retinal microvasculature: An optical coherence tomography angiography study

      Effect of blunt ocular trauma on retinal microvasculature: An optical coherence tomography angiography study

      Background To evaluate the retinal vascular changes and foveal avascular zone area in patients with unilateral blunt ocular trauma using optical coherence tomography angiography. Methods This retrospective study consisted of 50 traumatized and 50 contralateral sound eyes of the patients with blunt ocular trauma. The foveal avascular zone area, choriocapillaris flow area, foveal, parafoveal, and perifoveal vessel densities in both superficial capillary plexus and deep capillary plexus and central macular thickness were evaluated. Results There were no significant differences between traumatized and sound eyes in the foveal avascular zone area (p:0.36), choriocapillaris flow area (p:0.43), central ...

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    21. Close association of matrix metalloproteinase-9 levels with the presence of thin-cap fibroatheroma in acute coronary syndrome patients: Assessment by optical coherence tomography and intravascular ultrasonography

      Close association of matrix metalloproteinase-9 levels with the presence of thin-cap fibroatheroma in acute coronary syndrome patients: Assessment by optical coherence tomography and intravascular ultrasonography

      Background Thin-cap fibroatheroma (TCFA) has been suggested as a precursor lesion of coronary plaque rupture. As elevated plasma matrix metalloproteinase-9 (MMP-9) levels have been documented in patients with acute coronary syndrome (ACS), we sought to determine whether the presence of TCFA is linked to MMP-9 levels in these patients. Methods We evaluated 51 ACS patients with de novo culprit lesions who were examined via optical coherence tomography and intravascular ultrasound. Blood samples were obtained from the peripheral vein (PV) and the ostium and culprit lesion of the infarct-related coronary artery (CA) in the acute phase of ACS and from the ...

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    22. Evaluation of the insertion distance of the medial rectus in consecutive exotropia by means of intraoperative measure and optical coherence tomography

      Evaluation of the insertion distance of the medial rectus in consecutive exotropia by means of intraoperative measure and optical coherence tomography

      Purpose: To assess the agreement between the intraoperative measurements of the distance from the medial rectus muscles insertion to the limbus and preoperative spectral-domain optical coherence tomography (SD-OCT) in consecutive exotropia (cXT). Methods: An analysis was performed on total of 14 medial rectus (MR) muscles of 14 patients who underwent surgery for the treatment of cXT. The limbus-insertion distance of the MR muscles was measured using preoperative SD-OCT and intraoperatively using a calliper. The intraclass correlation coefficient (ICC) and Bland Altman plots were calculated to determine the agreement between the two methods, as well as the correlation. Results: Mean age ...

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    23. Adaptive optics ophthalmoscopy, multifocal ERG and OCTA in unique case of suspected torpedo maculopathy presenting with vitelliform lesion

      Adaptive optics ophthalmoscopy, multifocal ERG and OCTA in unique case of suspected torpedo maculopathy presenting with vitelliform lesion

      Purpose: To report the case of a ten-year old girl with torpedo maculopathy with a complete vitelliform lesion and describe associated optical coherence tomography (OCT), OCT angiography (OCTA), multifocal electroretinogram (ERG) and adaptive optics ophthalmoscopy (AOO) imaging of the lesion. Observations: An asymptomatic ten-year old girl with visual acuity of 20/15 OU was referred for evaluation of possible Best's disease of her left eye. The unilaterality, location, and shape of the lesion was consistent with torpedo maculopathy. OCT and autofluorescence (AF) revealed that the entire lesion was composed of subretinal hyperreflective material that was hyperautofluorescent, consistent with vitelliform ...

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    1-24 of 1328 1 2 3 4 ... 54 55 56 »
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