Optical coherence tomography angiography (OCT-A) permits visualization of the changes to the retinal circulation due to diabetic retinopathy (DR), a microvascular complication of diabetes. We demonstrate accurate segmentation of the vascular morphology for the superficial capillary plexus (SCP) and deep vascular complex (DVC) using a convolutional neural network (CNN) for quantitative analysis. Methods: The main CNN training dataset consisted of retinal OCT-A with a 6 × 6-mm field of view (FOV), acquired using a Zeiss PlexElite. Multiple-volume acquisition and averaging enhanced the vasculature contrast used for constructing the ground truth for neural network training. We used transfer learning from a CNN trained on smaller FOVs of the SCP acquired using different OCT instruments. Quantitative analysis of perfusion was performed on the resulting automated vasculature segmentations in representative patients with DR. Results: The automated segmentations of the OCT-A images maintained the distinct morphologies of the SCP and DVC. The network segmented the SCP with an accuracy and Dice index of 0.8599 and 0.8618, respectively, and 0.7986 and 0.8139, respectively, for the DVC. The inter-rater comparisons for the SCP had an accuracy and Dice index of 0.8300 and 0.6700, respectively, and 0.6874 and 0.7416, respectively, for the DVC. Conclusions: Transfer learning reduces the amount of manually annotated images required while producing high-quality automatic segmentations of the SCP and DVC that exceed inter-rater comparisons. The resulting intercapillary area quantification provides a tool for in-depth clinical analysis of retinal perfusion. Translational Relevance: Accurate retinal microvasculature segmentation with the CNN results in improved perfusion analysis in diabetic retinopathy.
AbtractHeat transfer issues in offshore wells construction and maintenance are increasing in last years. New production development scenarios are bringing challenges related to flow assurance, well construction and maintenance. Insulation projects are being considered to enable the oil and gas production. This paper presents the studies carried out in two projects of thermal insulation using VIT (Vacuum Insulated Tubing) technology and its structural and thermal evaluation using commercial software for numerical simulation.The present work aimed to evaluate VIT application in a production string to reduce APB (Annular Pressure Build-up) effects. This event happens when production flow is heating any well confined annulus causing its fluid expansion and increasing pressure inside it. In this way, annular pressure build up can lead casing collapse or burst even, in an exteme condition, production string damage. All these effects combined could lead to unacceptable well losses. VIT is uded to avoid APB effects.However, a VIT string isn't be able to provide a smiliar collapse and burst resistance than a usual same dimension tubing string. So VIT will dominate the string installation and production constraints due its back pressure lacking. In this way production string performance evaluation is a key issue on VIT design, length and technical specification.In order to evaluate the performance of the production string designed for two Petrobras projects, several numeric simulations were performed to evaluate loads and strains on intermediate casing and production string during its installation and well production, including the APB events.In addition, the length of pipes with insulation needed to mitigate the effect of AFE was defined and a sensitivity analysis performed to define the value of the minimum apparent thermal conductivity, which would allow operation without risk to well integrity.
Purpose: To report a case of acute zonal occult outer retinopathy in which adaptive optics (AO) facilitated visualization of abnormal photoreceptors previously thought to be in an area of normal retina on conventional optical coherence tomography (OCT).Methods: Case report.Results: A 51-year-old woman presents with 11-month history of photopsias and scotoma in the temporal visual field of her left eye. Ocular imaging including fluorescein angiography, fundus autofluorescence and OCT suggested the diagnosis of acute zonal occult outer retinopathy in the left eye. Adaptive optics optical coherence tomography (AO-OCT) revealed photoreceptor abnormalities not previously identified in conventional OCT, in areas apparently normal on multimodal imaging. On enface and cross-sectional AO-OCT, round and evenly spaced hyperreflectivity corresponding to normal cone mosaic (Pattern 1) was adjacent to unevenly and disrupted cone hyperreflectivity (Pattern 2) and areas with hyporeflectivity or no cone reflectivity (Pattern 3). Cross-sectional AO-OCT of Patterns 2 and 3 also revealed attenuation of ellipsoid zone with loss of interdigitation zone.Conclusion: Adaptive optics OCT documented cone photoreceptors in finer details than conventional OCT and revealed early changes in a patient with acute zonal occult outer retinopathy, in an area of the retina thought to be normal on conventional multimodal imaging. These findings may provide important insight into pathogenesis and progression of the disease.
A 21-year-old man presented with visual acuity of 20/200 in both eyes. The fundus picture, fluorescein angiography, and optical coherence tomography revealed severe bilateral acute posterior multifocal placoid pigment epitheliopathy and serous macular detachments. We treated the patient with triamcinolone acetonide, an intravitreal injection (4 mg/0.1 mL) in one eye and a posterior subtenon injection (40 mg/1 mL) in the other eye. Within 2 weeks the visual acuity was 20/80 in both eyes. At the 8-week follow-up visit his vision was 20/63 bilaterally. One year later the vision remained 20/63 in both eyes. In this patient, the triamcinolone acetonide injections, whether administered intravitreally or via the posterior subtenon route, achieved similar anatomic and functional recovery results.
Background Classic serpiginous choroiditis (SC) usually begins in the peripapillary area and spreads centrifugally, however, in some patients, the lesion can arise in the macular region. An association between lesions resembling classic SC and tuberculosis was recognized as a possibly distinct clinical entity and named as tuberculous serpiginous–like choroiditis. The differentiation of this tuberculous entity from SC is critical because the treatment of the former with immunosuppressive drugs leads to several potential adverse effects, and such treatment can have devastating consequences because of the worsening of a concomitant tuberculous infection. Case presentantion A 31-year-old woman presented with unilateral decreased vision and a fundus examination consistent with macular serpiginous choroiditis. A non-reactor tuberculin skin test and normal thoracic CT scan ruled out tuberculosis. However, after 2 months of treatment with steroids and immunosuppressive drugs, the contralateral eye developed similar lesions, further raising the suspicions of ocular tuberculosis. We conducted QuantiFERON® TB Gold, which was positive; hence, antituberculous therapy was started on the patient. The lesions started healing within a few weeks. After 1 year of finishing the therapy, the lesions remained healed without any recurrence. Conclusions Macular serpiginous-like choroiditis may be the initial presentation of presumed ocular tuberculosis. Nevertheless, the correct diagnosis of this entity can be challenging and delayed by the imprecise results from the currently available methods.
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