In vivo optical flow imaging

Abstract

Amplitude decorrelation measurement is sensitive to transverse flow and immune to phase noise in comparison to Doppler and other phase-based approaches. However, the high axial resolution of OCT makes it very sensitive to the pulsatile bulk motion noise in the axial direction, resulting in unacceptable signal to noise ratio (SNR). To overcome this limitation, a novel OCT angiography technique based on the decorrelation of OCT signal amplitude due to flow was created. The full OCT spectrum can be split into several narrower spectral bands, resulting in the OCT resolution cell in each band being isotropic and less susceptible to axial motion noise. Inter-B-scan decorrelation can be determined using the narrower spectral bands separately and then averaged. Recombining the decorrelation images from the spectral bands yields angiograms that use the full information in the entire OCT spectral range. Such images showed significant improvement of SNR for both flow detection and connectivity of microvascular networks when compared to other amplitude-decorrelation techniques. Further, creation of isotropic resolution cells can be useful for quantifying flow having equal sensitivity to axial and transverse flow. Such improved non-invasive imagery can be useful in the diagnosis and management of a variety of diseases.

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