Performance comparison of amplitude-decorrelation and speckle variance algorithms in spectrometer-based OCT angiography

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In this work, optical coherence tomography angiography (OCTA) was implemented on a spectrometer-based spectral domain OCT (SD-OCT) that was built on Michelson interferometer. Three methods of speckle analysis were implemented, i.e. amplitude decorrelation (AD), speckle variance (SV), and speckle to mean variance (SMV). The SMV is an in-house developed algorithm to accommodate the poor signal-to-noise ratio performance of the spectrometer-based SD-OCT. To compare the performance of the implemented algorithms, a flow phantom was constructed by embedding a capillary tube inside a diluted milk gel that represented static tissue. To mimic a blood flow beneath skin, diluted milk was pumped through the capillary tube with speeds of 0.3 to 3.5 mm·s−1 by using a syringe pump system. The performance of each OCTA algorithm, in terms of contrast-to-noise ratio (CNR), were measured and compared. The result shows that SMV algorithm provided the highest relative CNR value of 1.34, which is a 111 % improvement over the performance of SV algorithm.