1. Articles from Omar Al-Louzi

    1-9 of 9
    1. Voxel based morphometry in optical coherence tomography: validation and core findings

      Voxel based morphometry in optical coherence tomography: validation and core findings

      Optical coherence tomography (OCT) of the human retina is now becoming established as an important modality for the detection and tracking of various ocular diseases. Voxel based morphometry (VBM) is a long standing neuroimaging analysis technique that allows for the exploration of the regional differences in the brain. There has been limited work done in developing registration based methods for OCT, which has hampered the advancement of VBM analyses in OCT based population studies. Following on from our recent development of an OCT registration method, we explore the potential benefits of VBM analysis in cohorts of healthy controls (HCs) and ...

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    2. Simultaneous segmentation of retinal surfaces and microcystic macular edema in SDOCT volumes

      Simultaneous segmentation of retinal surfaces and microcystic macular edema in SDOCT volumes

      Optical coherence tomography (OCT) is a noninvasive imaging modality that has begun to find widespread use in retinal imaging for the detection of a variety of ocular diseases. In addition to structural changes in the form of altered retinal layer thicknesses, pathological conditions may also cause the formation of edema within the retina. In multiple sclerosis, for instance, the nerve fiber and ganglion cell layers are known to thin. Additionally, the formation of pseudocysts called microcystic macular edema (MME) have also been observed in the eyes of about 5% of MS patients, and its presence has been shown to be ...

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    3. Combined registration and motion correction of longitudinal retinal OCT data

      Combined registration and motion correction of longitudinal retinal OCT data

      Optical coherence tomography (OCT) has become an important modality for examination of the eye. To measure layer thicknesses in the retina, automated segmentation algorithms are often used, producing accurate and reliable measurements. However, subtle changes over time are difficult to detect since the magnitude of the change can be very small. Thus, tracking disease progression over short periods of time is difficult. Additionally, unstable eye position and motion alter the consistency of these measurements, even in healthy eyes. Thus, both registration and motion correction are important for processing longitudinal data of a specific patient. In this work, we propose a ...

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    4. Optical coherence tomography reflects brain atrophy in multiple sclerosis: A four-year study

      Optical coherence tomography reflects brain atrophy in multiple sclerosis: A four-year study

      Objective The aim of this work was to determine whether atrophy of specific retinal layers and brain substructures are associated over time, in order to further validate the utility of optical coherence tomography (OCT) as an indicator of neuronal tissue damage in patients with multiple sclerosis (MS). Methods Cirrus high-definition OCT (including automated macular segmentation) was performed in 107 MS patients biannually (median follow-up: 46 months). Three-Tesla magnetic resonance imaging brain scans (including brain-substructure volumetrics) were performed annually. Individual-specific rates of change in retinal and brain measures (estimated with linear regression) were correlated, adjusting for age, sex, disease duration, and ...

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    5. Optical coherence tomography reflects brain atrophy in MS: A four year study

      Optical coherence tomography reflects brain atrophy in MS: A four year study

      Objective : To determine whether atrophy of specific retinal layers and brain substructures are associated over time, in order to further validate the utility of optical coherence tomography (OCT) as an indicator of neuronal tissue damage in patients with multiple sclerosis (MS). Methods : Cirrus high definition OCT (including automated macular segmentation) was performed in 107 MS patients biannually (median follow-up: 46-months). Three-tesla magnetic resonance imaging brain scans (including brain-substructure volumetrics) were performed annually. Individual-specific rates of change in retinal and brain measures (estimated with linear regression) were correlated, adjusting for age, sex, disease duration, and optic neuritis (ON) history. Results : Rates ...

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    6. Segmentation of microcystic macular edema in Cirrus OCT scans with an exploratory longitudinal study

      Segmentation of microcystic macular edema in Cirrus OCT scans with an exploratory longitudinal study

      Microcystic macular edema (MME) is a term used to describe pseudocystic spaces in the inner nuclear layer (INL) of the human retina. It has been noted in multiple sclerosis (MS) as well as a variety of other diseases. The processes that lead to MME formation and their change over time have yet to be explained sufficiently. The low rate at which MME occurs within such diverse patient groups makes the identification and consistent quantification of this pathology important for developing patient-specific prognoses. MME is observed in optical coherence tomography (OCT) scans of the retina as changes in light reflectivity in ...

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    7. Applying an Open-Source Segmentation Algorithm to Different OCT Devices in Multiple Sclerosis Patients and Healthy Controls: Implications for Clinical Trials

      Applying an Open-Source Segmentation Algorithm to Different OCT Devices in Multiple Sclerosis Patients and Healthy Controls: Implications for Clinical Trials

      Background . The lack of segmentation algorithms operative across optical coherence tomography (OCT) platforms hinders utility of retinal layer measures in MS trials. Objective . To determine cross-sectional and longitudinal agreement of retinal layer thicknesses derived from an open-source, fully-automated, segmentation algorithm, applied to two spectral-domain OCT devices. Methods . Cirrus HD-OCT and Spectralis OCT macular scans from 68 MS patients and 22 healthy controls were segmented. A longitudinal cohort comprising 51 subjects (mean follow-up: 1.4 ± 0.9 years) was also examined. Bland-Altman analyses and interscanner agreement indices were utilized to assess agreement between scanners. Results . Low mean differences (−2.16 to ...

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    8. Longitudinal graph-based segmentation of macular OCT using fundus alignment

      Longitudinal graph-based segmentation of macular OCT using fundus alignment

      Segmentation of retinal layers in optical coherence tomography (OCT) has become an important diagnostic tool for a variety of ocular and neurological diseases. Currently all OCT segmentation algorithms analyze data independently, ignoring previous scans, which can lead to spurious measurements due to algorithm variability and failure to identify subtle changes in retinal layers. In this paper, we present a graph-based segmentation framework to provide consistent longitudinal segmentation results. Regularization over time is accomplished by adding weighted edges between corresponding voxels at each visit. We align the scans to a common subject space before connecting the graphs by registering the data ...

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    9. Automatic segmentation of microcystic macular edema in OCT

      Automatic segmentation of microcystic macular edema in OCT

      Microcystic macular edema (MME) manifests as small, hyporeflective cystic areas within the retina. For reasons that are still largely unknown, a small proportion of patients with multiple sclerosis (MS) develop MME—predominantly in the inner nuclear layer. These cystoid spaces, denoted pseudocysts, can be imaged using optical coherence tomography (OCT) where they appear as small, discrete, low intensity areas with high contrast to the surrounding tissue. The ability to automatically segment these pseudocysts would enable a more detailed study of MME than has been previously possible. Although larger pseudocysts often appear quite clearly in the OCT images, the multi-frame averaging ...

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    1-9 of 9
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    1. (9 articles) Johns Hopkins University
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    Automatic segmentation of microcystic macular edema in OCT Longitudinal graph-based segmentation of macular OCT using fundus alignment Applying an Open-Source Segmentation Algorithm to Different OCT Devices in Multiple Sclerosis Patients and Healthy Controls: Implications for Clinical Trials Segmentation of microcystic macular edema in Cirrus OCT scans with an exploratory longitudinal study Optical coherence tomography reflects brain atrophy in MS: A four year study Optical coherence tomography reflects brain atrophy in multiple sclerosis: A four-year study Combined registration and motion correction of longitudinal retinal OCT data Simultaneous segmentation of retinal surfaces and microcystic macular edema in SDOCT volumes Voxel based morphometry in optical coherence tomography: validation and core findings Vascular and Structural Alterations of the Choroid Evaluated by Optical Coherence Tomography Angiography and Enhanced-Depth Imaging Optical Coherence Tomography in Eyes with Reticular Pseudodrusen and Soft Drusen Total venous nature of retinal deep capillary plexus inferred by continuity of prominent middle limiting membrane sign in optical coherence tomography Evaluating Onychomycosis Outcomes 2 Months into an 11-month-long Efinaconazole Regimen: The Role of Optical Coherence Tomography