Abstract
Recently, parallel high A-line speed and wide field imaging for optical coherence tomography angiography (OCTA) has become more prevalent, resulting in a dramatic increase of data quantity which poses a challenge for real time imaging even for GPU in data processing. In this manuscript, we propose a new OCTA processing technique, Gabor optical coherence tomographic angiography (GOCTA), for label-free human retinal angiography imaging. In spectral domain optical coherence tomography (SDOCT), k-space resampling and Fourier transform (FFT) are required for the entire data set of interference fringes to calculate blood flow information in previous OCTA algorithms, which are computationally intensive. As adults' eye anterior-posterior radii are nearly constant, only 3 A-scan lines need to be processed to obtain the gross orientation of the retina by using a sphere model. Subsequently, the en face microvascular images can be obtained by using the GOCTA algorithm from interference fringes directly without the steps of k-space resampling, numerical dispersion compensation, FFT, and maximum (mean) projection, resulting in a significant improvement of the data processing speed by 4 to 20 times faster than the existing methods. GOCTA is potentially suitable for SDOCT systems in en face preview applications requiring real-time microvascular imaging.
Highlights
Optical coherence tomography (OCT) [1] technique, proposed in 1990s, is an emerging imaging modality for medical diagnostics and treatments
We performed Gabor optical coherence tomographic angiography (GOCTA) algorithm on the data set of healthy human eye from a commercial spectral domain optical coherence tomography (SDOCT) (AngioVue, OptoVue Inc.) to verify its performance
speckle variance OCT (SVOCT), UHS-optical micro-angiography (OMAG) and SVOCT algorithms were performed on the same data set to calculate microvascular images for comparison and the en face images were obtained by using mean projection within the depth range, same as the result obtained by Gabor filters
Summary
Optical coherence tomography (OCT) [1] technique, proposed in 1990s, is an emerging imaging modality for medical diagnostics and treatments. The second processing mode is inter-frame, which extracts blood flow information from multi-frames of structural images at each position, such as phase variance OCT (PVOCT) [9,10,11], speckle variance OCT (SVOCT) [12,13,14,15], correlation mapping OCT (cmOCT) [16,17,18], split-spectrum amplitude-decorrelation angiography (SSADA) [19] and differential standard deviation of log-scale intensity (DSDLI) [20], and ultrahigh sensitivity optical microangiography (UHS-OMAG) [21,22,23,24] For this mode, the sensitivity for microvasculature detection can be improved due to the time interval between two frames is longer than that between two A-scans, but the motion artifacts is more significant due to increase of time interval. We proposed a Gabor optical coherence tomographic angiography (GOCTA) algorithm extracting blood flow information from interference fringes directly without the time consuming steps mentioned above, which can decrease data processing time substantially
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