提出一种能够有效提高组织中小血流成像质量的优化多普勒光学相干层析术(DOCT).该方法通过利用谱域光学相干层析术(SDOCT)在同一横向位置对相邻和隔行A 扫相位差求平均的方法来实现.介绍了该方法的理论原理,并且通过血管模拟实验验证了其可行性.在模拟实验中,通过改变脂肪溶液在毛细玻璃管中的流速,利用传统相位方法和本文提出的方法分别对速度进行测量,然后分别计算速度的平均标准差并进行比较.对老鼠耳朵的血流进行活体测量,再分别利用两种方法进行多普勒速度图像的重构.实验结果证明,在小血流速度测量方面,本文提出的方法能够在不增加相邻A 扫时间间隔的情况下,有效地抑制由于系统相位不稳定而引起的相位噪声,从而提高血流速度图像的信噪比和测量精度.
A new method is presented forimaging the small blood flow velocities in vessels by a spectral domain optical coherence tomography based on averagingphasedifferences between adjacent and interval A-lines at the same lateral position. The proposed method is theoretically developed and validated by measurements of flowing particles within a glass capillary with known mean velocities. Mean standard deviations of different flow velocities of the particles are determined by the proposed method and compared with those determined by conventional phase-resolved method. In vivo experiments on a mouse ear and the Doppler flow velocity maps are reconstructed by both methods. The experimental results demonstrate that the proposed method can significantly suppress the phase noise caused by phase instabilities, improve the signal-to-noise ratio of phase difference and accuracy of velocity measurement for small blood flow without increasing the time interval between adjacent A-lines.
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