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Spatial-Temporal Speckle Variance in the En-Face View as a Contrast for Optical Coherence Tomography Angiography (OCTA)
Optical Coherence Tomography (OCT) is an adaptable depth-resolved imaging modality capable of creating a non-invasive ‘digital biopsy’ of the retina. One of the latest advances in OCT is optical coherence tomography angiography (OCTA), which utilizes the speckle variance or phase change in the signal to differentiate static tissue from blood flow. Unlike fluorescein angiography (FA), OCTA is contrast free and depth-resolved. By combining high-density scan patterns and image processing algorithms, both morphometric and functional data can be extracted into a depth-resolved vascular map. The proposed algorithm exploits the temporal-spatial relationship of the speckle variance to improve the contrast of the vessels in the en-face OCT with a single frame. The presented algorithm does not require the computationally inefficient decorrelation of multiple A-scans to detect vasculature that facilitates traditional OCTA. The proposed spatial temporal OCTA (ST-OCTA) methodology offers the potential for post-hoc analysis to improve the depth-resolved contrast of specific ocular structures, with the capability of using only a single frame for efficient screening of large sample volumes, and additionally enhanced by preprocessing with choice of frame averaging methods.
The prototype ST-OCTA algorithm was built in the ImageJ Macro language with open sourced components for maximum flexibility.
Biptigen R2200 Leica Envisu R-Class
OcuScience iVivo Lab OCT
Input is Bioptigen .OCT files or TIFF