Correlation of Retinal Thickness and Swept-Source Optical Coherence Tomography Angiography Derived Vascular Changes in Patients with Neovascular Age-Related Macular Degeneration.

Purpose: The aim of this study was to investigate whether structural OCT changes, in specific retinal thickness, is associated with the vascular response within the nAMD CNV lesion. In other words, whether SSOCTA derived parameters may prove suitable to assess CNV activity in future.Methods: During the first 3 months patients were prospectively followed with visits at days 7, and 14 after each anti-VEGF treatment up to day 90. At baseline, day 30 and 60 Aflibercept was administered. OCT-derrived retinal thickness (RT) and OCTA-derived CNV lesion parameters (vessel area [VA]), total vessel length [TVL], total number of junctions [TNJ], junction density [JD]) were determined. Parameters were exported from SSOCT/A (PlexElite, Zeiss) images using the semi-automated AngioTool software. Additionally, the superficial and deep vascular plexus fractal dimension of the para- and perifoveal region were identified. Consequently, all OCTA derived parameters were correlated with RT.Results: 16 consecutive patients presenting with treatment-naïve, SSOCTA-positive CNV lesions were included. A weak to moderate statistically significant correlation was found between the mean RT of the inner as well as the outer ETDRS ring with the SSOCTA-derived vascular markers vessel area (VA; r2 = -0.38, p < .001; r2 = -0.47, p < .001, respectively), total vessel length, (TVL; r2 = -0.38, p < .001; r2 = -0.48, p < .001, respectively) and total number of junctions (TNJ; r2 = -0.35, p < .001; r2 = -0.44, p < .001, respectively). Junctions density (JD), and all variables based on fractal dimension (FD) did not show statistically significant correlations with retinal thickness measurements.Conclusions: In summary, we could confirm a moderate, however, statistically significant correlation between mean para- and perifoveal retinal thickness and the SSOCTA derived vascular parameters VA, TVL, and TNJ. This leads us to the conclusion that an SSOCTA-based activity analysis of the CNV complex is not yet a substitute for retinal thickness or in-depth fluid analysis in patients with nAMD.

Polyaniline/Platinum Composite Cathode Catalysts Towards Durable Polymer Electrolyte Membrane Fuel Cells.

Polymer stabilization proved to be a promising approach to increase the catalytic performance of common platinum/carbon based cathode catalysts (Pt/C) used in polymer electrolyte membrane fuel cells (PEMFCs). Platinum and polyaniline composite catalysts (Pt/C/PANI) were prepared by combining chemical polymerization reactions with anion exchange reactions. Electrochemical ex-situ characterizations of the decorated Pt/C/PANI catalysts show high catalytic activity toward the oxygen reduction reaction (ORR) and, more importantly, a significant enhanced durability compared to the undecorated Pt/C catalyst. Transmission electron microscopy (TEM) investigations reveal structural benefits of Pt/C/PANI for ORR catalysis. All studies confirm high potential of Pt/C/PANI for practical fuel cell application.

Three-dimensional steady-state MR angiography of the lower extremities.

Volume steady-state black-blood magnetic resonance imaging was evaluated as a method for depicting lower extremity vasculature. In steady-state imaging, flow has low signal intensity because motion destroys the coherence of transverse magnetization. To optimize image contrast, computations and measurements were obtained for the three-dimensional (3D) GRASS (gradient-recalled acquisition in the steady state) and 3D SSFP (steady-state free precession) sequences and a range of TRs and flip angles to determine optimal vessel-muscle contrast. The best results were achieved with a 3D GRASS sequence with a TR msec/TE msec of 25/5 and a flip angle of 30 degrees. Coronal images of the femoral and popliteal vessels were obtained in healthy volunteers with various fields of view and voxel sizes. Inflow of unsaturated spins from outside the image region, yielding high signal intensity, could be a potential drawback in steady-state black-blood imaging; however, problems can be avoided by using coronal acquisitions and large fields of view. Steady-state black-blood imaging depicts vessels with high accuracy and is faster and free of flow artifacts.

Optimization of submillimeter-resolution MR imaging methods for the inner ear.

Submillimeter-resolution magnetic resonance (MR) imaging of the inner ear is valuable for diagnosis and treatment planning. Its main advantage for investigations of underlying disease is that it can directly depict the fluid spaces of the membranous labyrinth rather than define only the bony canal, as does computed tomography. A systematic evaluation of factors influencing high-resolution three-dimensional (3D) gradient-echo imaging of the inner ear with a standard clinical MR system is presented. This includes the evaluation of various radio-frequency coils, the design of steady-state pulse sequences, and the optimization of acquisition parameters. A quantitative analysis was facilitated by computer simulations and image processing. The highest signal-to-noise ratio for the membranous labyrinth was obtained with a single 3-inch (7.6-cm) receiver coil and a 3D GRASS (gradient-recalled acquisition in the steady state) sequence with the minimal achievable TR msec/TE msec of 25/7 and a 40 degrees--60 degrees flip angle, which yielded acceptable images with minimal voxel volumes of 0.1 mm3 in 14 minutes.