Quantifying cilia beat frequency using high-speed video microscopy: Assessing frame rate requirements when imaging...

Area of Science:

• Biophysics
• Cell Biology
• Physiology

Background:

• Motile cilia are crucial for physiological functions.
• Cilia beat frequency (CBF) is a key metric for assessing cilia motility.
• Inconsistent frame rates in video microscopy complicate CBF measurement.

Purpose of the Study:

• Determine the optimal frame rate for accurate CBF assessment.
• Evaluate the applicability of the Nyquist theorem for setting sampling rates.

Main Methods:

• Collected high-speed videos (>600 fps) of mouse airway and ependymal cilia.
• Down-sampled videos to various frame rates (30-300 fps).
• Quantified CBF using manual counting and automated MATLAB scripts.

Main Results:

• CBF measurements were significantly impaired at lower frame rates (30-60 fps).
• Accurate CBF assessment required a minimum frame rate of 150 fps.
• Automated CBF measurement accuracy improved at higher frame rates (>150 fps).

Conclusions:

• The Nyquist theorem is not suitable for determining sampling rates for CBF measurement.
• A sampling rate 3-4 times the CBF is recommended for accurate assessment, especially for automated methods.