Absolute flow measurement in chicken embryo based on optical coherence tomography with direct Doppler angle measuring

Abnormal blood flow in the early stage of embryonic heart can lead to cardiac defects. Thus, accurate flow measurement in the embryonic heart is important for related studies. Optical coherence tomography (OCT) is a noninvasive imaging approach which can provide flow velocity distribution information with high spatial and temporal resolution. However, OCT is only sensitive to velocity components parallel to the probing beam. To measure absolute flow velocity, additional information, such as Doppler angle, is required. Here, we propose a practical method to measure Doppler angle by introducing a dividing head to probe the arm of OCT. The incident angle of the probe beam can be controlled by rotating the dividing head. With the scale of the dividing head, rotating angle can be obtained. In each measurement, probe beam is adjusted to a proper angle by real time flow monitoring. Then, the probe beam is rotated perpendicularly to the flow velocity, i.e. Doppler angle is pi /2, and the Doppler angle can be calculated. This method is validated by capillary phantom. Last, blood flow in the early stage of chicken embryo is measured in vivo by the proposed method.

Automated summary

Abnormal blood flow in the early stage of embryonic heart can lead to cardiac defects. Accurate flow measurement in the embryonic heart is important for related studies. Optical coherence tomography (OCT) is a noninvasive imaging approach that can provide high-resolution flow velocity distribution information. The proposed method in this study introduces a dividing head to probe the arm of OCT, allowing for the measurement of the Doppler angle and the calculation of absolute flow velocity. The method is validated using a capillary phantom and further applied to measure blood flow in the early stage of chicken embryo in vivo.