Variable-range Doppler optical microangiography using stabilized step scanning and phase variance binarized mask

Lei Shi; Jia Qin; Suzan Dziennis; Ruikang K. Wang

doi:10.1117/12.2008708

1 March 2013 Variable-range Doppler optical microangiography using stabilized step scanning and phase variance binarized mask

Lei Shi, Jia Qin, Suzan Dziennis , Ruikang K. Wang

Author Affiliations +

Proceedings Volume 8580, Dynamics and Fluctuations in Biomedical Photonics X; 858018 (2013) https://doi.org/10.1117/12.2008708
Event: SPIE BiOS, 2013, San Francisco, California, United States

Abstract

Skipping various numbers of A-lines is effective to obtain multi-range velocimetry using Doppler optical coherence tomography (DOCT). High correlation between A-lines is a fundamental prerequisite for DOCT processing. Therefore, high oversampling is normally necessary, especially when skipping A-lines. That requires quite a long time of imaging, which might not be acceptable on some occasions. Step-scanning protocol, which captures repeated A-scans, has been employed for multi-range DOCT previously. We develop it by waiting for the scanner to stabilize, but not capturing continuously. In this way the cross-correlation of step scanning maintains almost constant for all the captured A-lines, and is higher than that of conventional linear scanning with similar imaging time. Due to the limited numbers of A-lines at each lateral position, we choose previously proposed high-pass filter in ultrahigh sensitive optical microangiography (OMAG) to enhance flow sensitivity. Doppler processing is implemented after the filter, both of which utilize A-line skipping to achieve variable velocity ranges. The obtained Doppler signal in blood flow is encircled by much noise in non-flow area. This is because that the static components are rejected by the filter, leaving random phase noise. The phase variance, which is a flow indicator, is employed to generate a binary mask to extract the Doppler signal out of noise. The technique is demonstrated in bi-directional cross-section and maximum projection en face images of middle cerebral artery (MCA) occluded mouse model. The vasculature responses from artery down to capillary during baseline, occlusion and reperfusion are illustrated. In some arteries that branch from MCA the flow is reversed but not simply reduced or vanished.

Citation Download Citation

Lei Shi, Jia Qin, Suzan Dziennis , and Ruikang K. Wang "Variable-range Doppler optical microangiography using stabilized step scanning and phase variance binarized mask", Proc. SPIE 8580, Dynamics and Fluctuations in Biomedical Photonics X, 858018 (1 March 2013); https://doi.org/10.1117/12.2008708

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