Phase unwrapping for Doppler spectral domain optical coherence tomography flow measurement

Abstract

Doppler optical coherence tomography (OCT) offers additional flow velocity information, which extends the application of OCT. Phase wrapping is the inherent problem that limits measureable range of Doppler OCT. We propose a phase unwrapping method which is suitable for correcting phase in Doppler OCT images. Points (pixels) in flow region are divided into groups according to the radial distance. Points in the same group are supposed to have close velocity. Phase unwrapping algorithm begins at the boundary layer group and is performed sequentially toward the center. Using the proposed criterion, points in a group are separated into two categories, signal points and noise points. Wrapping rounds are determined for signal points phase unwrapping. Mean value of the corrected signal points replaces the noise points for noise reduction. The method is validated with capillary tube flow phantom and in vivo blood flow. K E Y W O R D SDoppler, flow measurement, medical and biological imaging, optical coherence tomography, phase unwrapping

The Stress Phase Angle Measurement Using Spectral Domain Optical Coherence Tomography

“…Figure 7b displays the corresponding M-mode Doppler flow image, where the blue areas indicate phase wrapping caused by flow velocities exceeding the measurable range of the SD-OCT system. To address this, the phase-unwrapped image is presented in Figure 7c [34]. Thus, the SPA can be achieved by comparing the phase difference between the CS and WSR (Figure 7d).…”