Phase-resolved dynamic wavefront imaging of cilia metachronal waves.

The coordination and the directional order of ciliary metachronal waves are the major factors that determine the effectiveness of mucociliary clearance (MCC). Even though metachronal waves play an essential part in immune response, clinical diagnostic tools and imaging techniques that can reliably and efficiently capture their spatial distribution and function are currently limited. We present label-free high-speed visualization of ciliary metachronal wave propagations in freshly-excised tracheal explants using a spectrally-encoded interferometric microscope over a two-dimensional (2D) plane of 0.5 mm × 0.5 mm at an acquisition rate of 50 frame-per-second. Furthermore, phase-resolved enhanced dynamic (PHRED) analysis of time-series doppler images was performed, where spatial-temporal characteristics of cilia metachronal wave motions are revealed through frequency component analysis and spatial filtering. The PHRED analysis of phase-resolved Doppler (PRD) images offers a capability to distinguish the propagation direction of metachronal waves, and quantitatively assess amplitude and dominant frequency of cilia beating at each spatial location. Compared to the raw PRD images, the phase-resolved dynamic wavefront imaging (PRDWI) method showed the direction and coordination of collective cilia movement more distinctively. The PRDWI technique can have broad application prospects for the diagnosis of human respiratory diseases and evaluation of the curative effect of treatments and open new perspectives in biomedical sciences.

纤毛异相波的协调性和方向顺序是决定黏液纤毛清除（MCC）有效性的主要因素。尽管异相波在免疫反应中起着至关重要的作用，但能够可靠且高效地捕捉其空间分布和功能的临床诊断工具和成像技术目前还很有限。 我们利用光谱编码干涉显微镜，以每秒50帧的采集速率，在0.5毫米×0.5毫米的二维平面上，对新鲜切除的气管外植体中的纤毛异相波传播进行了无标记高速可视化。此外，还对时间序列多普勒图像进行了相位分辨增强动态（PHRED）分析，通过频率成分分析和空间滤波揭示了纤毛异相波运动的时空特征。 相位分辨多普勒（PRD）图像的PHRED分析能够区分异相波的传播方向，并定量评估每个空间位置纤毛摆动的幅度和主频率。与原始的PRD图像相比，相位分辨动态波前成像（PRDWI）方法更清晰地显示了纤毛集体运动的方向和协调性。 PRDWI技术在人类呼吸系统疾病的诊断以及治疗效果评估方面具有广泛的应用前景，并为生物医学科学开辟了新的视角。