Gold nanorods as a contrast agent for Doppler optical coherence tomography

Purpose: To investigate gold nanorods (GNRs) as a contrast agent to enhance Doppler optical coherence tomography (OCT) imaging of the intrascleral aqueous humor outflow. Methods: A serial dilution of GNRs was scanned with a spectral-domain OCT device (Bioptigen, Durham, NC) to visualize Doppler signal. Doppler measurements using GNRs were validated using a controlled flow system. To demonstrate an application of GNR enhanced Doppler, porcine eyes were perfused at constant pressure with mock aqueous alone or 1.0×10 12 GNR/mL mixed with mock aqueous. Twelve Doppler and volumetric SD-OCT scans were obtained from the limbus in a radial fashion incremented by 30°, forming a circular scan pattern. Volumetric flow was computed by integrating flow inside non-connected vessels throughout all 12 scans around the limbus. Results: At the GNR concentration of 0.7×1012 GNRs/mL, Doppler signal was present through the entire depth of the testing tube without substantial attenuation. A well-defined laminar flow profile was observed for Doppler images of GNRs flowing through the glass capillary tube. The Doppler OCT measured flow profile was not statistically different from the expected flow profile based upon an autoregressive moving average model, with an error of -0.025 to 0.037 mm/s (p = 0.6435). Cross-sectional slices demonstrated the ability to view anterior chamber outflow ex-vivo using GNR-enhanced Doppler OCT. Doppler volumetric flow measurements were comparable to flow recorded by the perfusion system. Conclusions: GNRs created a measureable Doppler signal within otherwise silent flow fields in OCT Doppler scans. Practical application of this technique was confirmed in a constant pressure ex-vivo aqueous humor outflow model in porcine eyes. © 2014 Wang et al

Agreement among graders on Heidelberg retina tomograph (HRT) topographic change analysis (TCA) glaucoma progression interpretation.

PURPOSE:To evaluate agreement among experts of Heidelberg retina tomography's (HRT) topographic change analysis (TCA) printout interpretations of glaucoma progression and explore methods for improving agreement. METHODS: 109 eyes of glaucoma, glaucoma suspect and healthy subjects with 655 visits and 2 good quality HRT scans acquired at each visit were enrolled. TCA printouts were graded as progression or non-progression. Each grader was presented with 2 sets of tests: a randomly selected single test from each visit and both tests from each visit. Furthermore, the TCA printouts were classified with grader's individual criteria and with predefined criteria (reproducible changes within the optic nerve head, disregarding changes along blood vessels or at steep rim locations and signs of image distortion). Agreement among graders was modelled using common latent factor measurement error structural equation models for ordinal data. RESULTS: Assessment of two scans per visit without using the predefined criteria reduced overall agreement, as indicated by a reduction in the slope, reflecting the correlation with the common factor, for all graders with no effect on reducing the range of the intercepts between the graders. Using the predefined criteria improved grader agreement, as indicated by the narrower range of intercepts among the graders compared with assessment using individual grader's criteria. CONCLUSIONS: A simple set of predefined common criteria improves agreement between graders in assessing TCA progression. The inclusion of additional scans from each visit does not improve the agreement. We, therefore, recommend setting standardised criteria for TCA progression evaluation

Border Regimes and Security in an Enlarged European Community: Implications of the Entry into Force of the Amsterdam Treaty

Digitised version produced by the EUI Library and made available online in 2020.A later version of this paper was subsequently published in the book 'Europe Unbound: Enlraging and Re-shaping the Boundaries of the European Union' edited by Jan Zielonka, New York, Routledge, 2002

Structural-physiological relationships in the visual system upon glutamate excitotoxicity in the eye using diffusion tensor imaging and manganese-enhanced MRI

Scientific Session: Cell Memories: Cell Tracking & MEMRI: no. 0697Summa Cum Laude Merit AwardExcitotoxicity has been linked to the pathogenesis of ocular diseases and injuries and may involve early degeneration of both anterior and posterior visual pathways. To date, the spatiotemporal patterns of neurodegeneration in the visual system and the relationships with excitotoxic retinal injury and optic neuropathy are not fully elucidated. In this study, we employed DTI and MEMRI to study the microstructural alterations, anterograde Mn transport and their correlations along the visual pathway upon N-methyl-D-aspartate (NMDA)-induced glutamate excitotoxicity in the eye, in order to determine the pathophysiological events and structural-physiological relationships in the injured visual pathways

Structural-physiological relationships in the visual system upon glutamate excitotoxicity in the eye using diffusion tensor imaging and manganese-enhanced MRI

Scientific Session: Cell Memories: Cell Tracking & MEMRI: no. 0697Summa Cum Laude Merit AwardExcitotoxicity has been linked to the pathogenesis of ocular diseases and injuries and may involve early degeneration of both anterior and posterior visual pathways. To date, the spatiotemporal patterns of neurodegeneration in the visual system and the relationships with excitotoxic retinal injury and optic neuropathy are not fully elucidated. In this study, we employed DTI and MEMRI to study the microstructural alterations, anterograde Mn transport and their correlations along the visual pathway upon N-methyl-D-aspartate (NMDA)-induced glutamate excitotoxicity in the eye, in order to determine the pathophysiological events and structural-physiological relationships in the injured visual pathways