Functional optical coherence tomography (OCT) for mapping of cilia beat frequency in the human fallopian tube ex vivo

Cilia beat frequency (CBF) is an essential measure of fallopian tube function. In the present study, we adapted a previously developed functional optical coherence tomography (OCT) method, to spatially map and quantify CBF in one human sample ex vivo. Time lapsed image sets at different locations were acquired using OCT (n=8) and 50x magnification brightfield (BF) microscopy (n=2) as ground truth. A sliding window Fourier analysis was performed on OCT and BF image sets to quantify CBF on a pixel-by-pixel basis. Parameters were optimized to maximize contrast of cilia, and were uniformly applied for all OCT image sets. CBF color maps were created and were qualitatively compared to unprocessed OCT intensity image sets to evaluate the spatial mapping accuracy of CBF values. Line plots of amplitude vs. frequency at 1 second intervals, and pixel peak frequency histograms of whole image sets, were created to visualize the dominant CBFs. An analysis of variance was used to compare CBFs as measured with OCT and BF microscopy. Our results revealed qualitatively accurate spatial mapping of non-zero CBF values to pixels in ciliated areas, which were visibly appreciable on unprocessed intensity image sets. There was no significant difference between the dominant CBFs as measured with OCT and ground truth BF microscopy (3.2 ± 1.6 Hz, 3.2 ± 0, p=0.97). Bulk sample movement was a significant source of temporal variability and amplified high-frequency noise.