![]() ![]() For longitudinal monitoring, use of the same image processing method is recommended. To determine if these inconsistent results are clinically meaningful, and which method is more suitable for clinical use, our results provide further evidence that detailed understanding of the image analysis method is essential for reliable decision making for patients with retinal pathology. ![]() Both methods allow the segmentation of the vascular network and the examination of vascular density parameters, but they produce largely inconsistent results. Using MHF, the vascular network gets more fragmented by an average of 40% compared to ST. The noise level reduction of the two methods were almost identical (noise levels: 65.8% with MHT and 65.24% with ST). Values of VDI were considerably higher with ST than with MHF, while standard deviation was still significantly higher with ST (range : 2.459 ± 0.144 to 2.71 ± 0.084 and 2.983 ± 0.929 to 5.19 ± 1.064 for VDI with MHF and ST, respectively). Regarding SkD and VD, MHF generally gave higher values than ST. We analyzed the results in order to establish similarities or potentially relevant differences. We assessed Vessel Density (VD), Skeleton Density (SkD) and Vessel Diameter Index (VDI). After extracting the images, two semi-manual post-processing techniques, the already established Mexican hat filtering (MHF) and an alternative, the Shanbhag thresholding (ST) were applied. OCTA examinations of 38 subjects were performed. ![]() © 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement.The aim of this study was to evaluate qualitative and quantitative differences in vascular density analysis of an established and a novel alternative for post-processing on optical coherence tomography angiography (OCTA) images in healthy individuals. It is expected that the proposed system setup would have useful and practical applications in the investigations of the vasculature in the birefringent tissue samples both pre-clinically and clinically. The proposed PS-OCTA system is employed to visualize the birefringent components and the vascular networks of the human skin in vivo. Taking the advantages of the dual-channel PS-OCT configuration, the polarization induced artifacts are eliminated from OCTA vascular imaging. OCTA is used to acquire high-resolution images of functional microvascular networks permeating the scanned tissue volume. PS-OCT is used to provide birefringent contrast where the color-encoded Stokes parameters are used to obtain high contrast polarization-state images. The system is furnished with a swept source OCT (SS-OCT) that incorporates two imaging modes: OCTA imaging and polarization-sensitive imaging. To mitigate this issue, we demonstrate polarization-sensitive optical coherence tomography (PS-OCT) to image microvascular information within a living sample without polarization induced artifacts. This effect can diminish the ability of OCTA to detect vascular information, leading to an erroneous interpretation of the final OCTA images. When imaging birefringent samples using optical coherence tomography angiography (OCTA), the phase retardation may appear opposite to the phase change due to the blood flow in the orthogonal signals, for which a cancellation effect can occur when deriving OCTA signals. ![]()
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