1. 1-12 of 12
    1. State-of-the-art in retinal optical coherence tomography image analysis

      State-of-the-art in retinal optical coherence tomography image analysis

      Optical coherence tomography (OCT) is an emerging imaging modality that has been widely used in the field of biomedical imaging. In the recent past, it has found uses as a diagnostic tool in dermatology, cardiology, and ophthalmology. In this paper we focus on its applications in the field of ophthalmology and retinal imaging. OCT is able to non-invasively produce cross-sectional volumetric images of the tissues which can be used for analysis of tissue structure and properties. Due to the underlying physics, OCT images suffer from a granular pattern, called speckle noise, which restricts the process of interpretation. This requires specialized ...

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    2. Real-time epidural anesthesia guidance using optical coherence tomography needle probe

      Real-time epidural anesthesia guidance using optical coherence tomography needle probe

      Epidural anesthesia is one of the most widely used anesthesia methods. Due to lack of visual feedback to guide needle navigation, failure rate of epidural anesthesia is up to 20%, and the complication rate of peripheral nerve block approaches 10%, with the potential of permanent nerve damage. To address these difficulties, needle insertion under ultrasound guidance and fluoroscopy has been introduced. However, they do not provide adequate resolution and contrast to distinguish the tissue layers that the needle travels through or to specifically identify the epidural space. To improve the accuracy of epidural space identification, we developed a small hand-held ...

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    3. Algorithms for improved 3-D reconstruction of live mammalian embryo vasculature from optical coherence tomography data

      Algorithms for improved 3-D reconstruction of live mammalian embryo vasculature from optical coherence tomography data

      Background: Robust reconstructions of the three-dimensional network of blood vessels in developing embryos imaged by optical coherence tomography (OCT) are needed for quantifying the longitudinal development of vascular networks in live mammalian embryos, in support of developmental cardiovascular research. Past computational methods [such as speckle variance (SV)] have demonstrated the feasibility of vascular reconstruction, but multiple challenges remain including: the presence of vessel structures at multiple spatial scales, thin blood vessels with weak flow, and artifacts resulting from bulk tissue motion (BTM). Methods: In order to overcome these challenges, this paper introduces a robust and scalable reconstruction algorithm based on ...

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    4. Anterior segment optical coherence tomography evaluation of ocular graft-versus-host disease: a case study

      Anterior segment optical coherence tomography evaluation of ocular graft-versus-host disease: a case study

      To explore ocular graft-versus-host disease (GVHD), anterior segment optical coherence tomography (AS-OCT) imaging of eyelids, tear meniscus, cornea and conjunctiva is performed in subsequent sessions on a patient who has ocular GVHD after allogeneic related donor stem cell transplant. The OCT results are presented together with those from a normal subject. OCT imaging is promising in visualizing several ocular GVHD manifestations, such as abnormal meibomian gland orifice (MGO), conjunctival keratinization, conjunctival hyperemia and chemosis, corneal epithelium opacification, thinning and sloughing. This case study demonstrates the capability of AS-OCT in the imaging and monitoring of ocular GVHD, which may be useful ...

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    5. Imaging endocervical mucus anatomy and dynamics in macaque female reproductive track using optical coherence tomography

      Imaging endocervical mucus anatomy and dynamics in macaque female reproductive track using optical coherence tomography

      Background: Endocervical mucus acts as an important barrier to block human immunodeficiency virus (HIV) infection and other sexually transmitted diseases (STDs). Disruption of the mucus layer increases the risk of infection for females. An effective method to image the mucus properties can serve as a pre-screening step to risk-stratify the susceptible population. Methods: We proposed to use optical coherence tomography (OCT) to quantitatively measure the thickness of endocervical mucus. We used a home-built bench-top OCT system to monitor the dynamic change in mucus thickness of a cultivated sample. We also fabricated a prototype endoscopic OCT probe to demonstrate potential in ...

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    6. Real-time automated thickness measurement of the in vivo human tympanic membrane using optical coherence tomography

      Real-time automated thickness measurement of the in vivo human tympanic membrane using optical coherence tomography

      Background: Otitis media (OM), an infection in the middle ear, is extremely common in the pediatric population. Current gold-standard methods for diagnosis include otoscopy for visualizing the surface features of the tympanic membrane (TM) and making qualitative assessments to determine middle ear content. OM typically presents as an acute infection, but can progress to chronic OM, and after numerous infections and antibiotic treatments over the course of many months, this disease is often treated by surgically inserting small tubes in the TM to relieve pressure, enable drainage, and provide aeration to the middle ear. Diagnosis and monitoring of OM is ...

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    7. Pulsatile motion of trabecular meshwork in a patient with iris cyst by phase-sensitive optical coherence tomography: a case report

      Pulsatile motion of trabecular meshwork in a patient with iris cyst by phase-sensitive optical coherence tomography: a case report

      45-year-old man was diagnosed with a 3 mm × 3 mm iris cyst located at 9 o’clock behind iris and protruding into temporal angle by slit lamp examination, gonioscopy, and ultrasound biomicroscopy (UBM). Phase-sensitive optical coherence tomography (PhS-OCT) was applied on this case for the quantitative measurements of trabecular meshwork (TM) motion. The frequency of TM motion was with the same rhythm of the patient’s peripheral pulse. Its amplitude on the closed angle region showed significant smaller than the open angle region. PhS-OCT can be a useful tool for the diagnosis and follow-up in ocular diseases surrounding iridocorneal angle.

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    8. Changes in cochlear blood flow in mice due to loud sound exposure measured with Doppler optical microangiography and laser Doppler flowmetry

      Changes in cochlear blood flow in mice due to loud sound exposure measured with Doppler optical microangiography and laser Doppler flowmetry

      In this work we determined the contributions of loud sound exposure (LSE) on cochlear blood flow (CoBF) in an in vivo anesthetized mouse model. A broadband noise system (20 kHz bandwidth) with an intensity of 119 dB SPL, was used for a period of one hour to produce a loud sound stimulus. Two techniques were used to study the changes in blood flow, a Doppler optical microangiography (DOMAG) system; which can measure the blood flow within individual cochlear vessels, and a laser Doppler flowmetry (LDF) system; which averages the blood flow within a volume (a hemisphere of ~1.5 mm ...

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    9. Breaking diffraction limit of lateral resolution in optical coherence tomography

      Breaking diffraction limit of lateral resolution in optical coherence tomography

      Quantitative imaging of biomedical specimens is essential in biomedical study and diagnosis. Given excellent capability in three-dimensional (3D) imaging, optical coherence tomography (OCT) has been extensively used in ophthalmic imaging, vascular medicine, dermatological study, etc. Lateral resolution of the OCT is light diffraction limited, which precludes the feasibility of quantitative assessment of individual cells. In this paper, we demonstrated the feasibility of breaking diffraction-limit in OCT imaging through virtually structured detection (VSD). OCT examination of optical resolution target verified resolution doubling in the VSD based OCT imaging. Super-resolution OCT identification of individual frog photoreceptors was demonstrated to verify the potential ...

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    10. Uniform enhancement of optical micro-angiography images using Rayleigh contrast-limited adaptive histogram equalization

      Uniform enhancement of optical micro-angiography images using Rayleigh contrast-limited adaptive histogram equalization

      Optical microangiography is an imaging technology that is capable of providing detailed functional blood flow maps within microcirculatory tissue beds in vivo . Some practical issues however exist when displaying and quantifying the microcirculation that perfuses the scanned tissue volume. These issues include: (I) Probing light is subject to specular reflection when it shines onto sample. The unevenness of the tissue surface makes the light energy entering the tissue not uniform over the entire scanned tissue volume. (II) The biological tissue is heterogeneous in nature, meaning the scattering and absorption properties of tissue would attenuate the probe beam. These physical limitations ...

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    11. Label-free imaging of blood vessel morphology with capillary resolution using optical microangiography

      Label-free imaging of blood vessel morphology with capillary resolution using optical microangiography
      Several tissue pathologies are correlated with changes in the blood vessel morphology and microcirculation that supplies the tissue. Optical coherence tomography (OCT) is an imaging technique that enables acquiring non-invasive three-dimensional images of biological structures with micrometer resolution. Optical microangiography (OMAG) is a method of processing OCT data which enables visualizing the three-dimensional blood vessel morphology within biological tissues. OMAG has high spatial resolution which allows visualizing single capillary vessels, and does not require the use of contrast agents. The intrinsic optical signals backscattered by the moving blood cells inside blood vessels are used as the contrast for which OMAG ...
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    12. Carina shift as a mechanism for side-branch compromise following main vessel intervention: Insights from three-dimensional optical coherence tomography

      Carina shift as a mechanism for side-branch compromise following main vessel intervention: Insights from three-dimensional optical coherence tomography

      Three-dimensional rendering of optical coherence tomography (OCT) images is a method that can be used for providing additive information for assessing the result of percutaneous coronary intervention (PCI), especially in complex lesions such as in bifurcations (1). While plaque shift has been considered the main underlying mechanism for side-branch compromise after stenting (2), new theories challenge the role of plaque shift and suggest carina shift to be a major contributor (3-6). We present a case were on-line three-dimensional OCT was used to demonstrate the role of carina shift in side-branch pinching, following main vessel intervention. A 53-year old female underwent ...

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    1-12 of 12
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