title: Measurement of ciliary beat frequency using Doppler optical coherence tomography.
abstract: BACKGROUND
  Measuring ciliary beat frequency (CBF) is a technical challenge and difficult to perform in vivo. Doppler optical coherence tomography (D-OCT) is a mesoscopic noncontact imaging modality that provides high-resolution tomographic images and detects micromotion simultaneously in living tissues. In this work we used D-OCT to measure CBF in ex vivo tissue as the first step toward translating this technology to clinical use.
  
  
  METHODS
  Fresh ex vivo samples of rabbit tracheal mucosa were imaged using both D-OCT and phase-contrast microscopy (n = 5). The D-OCT system was designed and built to specification in our lab (1310-nm swept source vertical-cavity surface-emitting laser [VCSEL], 6-μm axial resolution). The samples were placed in culture and incubated at 37°C. A fast Fourier transform was performed on the D-OCT signal recorded on the surface of the samples to gauge CBF. High-speed digital video of the epithelium recorded via phase-contrast microscopy was analyzed to confirm the CBF measurements.
  
  
  RESULTS
  The D-OCT system detected Doppler signal at the epithelial layer of ex vivo rabbit tracheal samples suggestive of ciliary motion. CBF was measured at 9.36 ± 1.22 Hz using D-OCT and 9.08 ± 0.48 Hz using phase-contrast microscopy. No significant differences were found between the 2 methods (p > 0.05).
  
  
  CONCLUSIONS
  D-OCT allows for the quantitative measurement of CBF without the need to resolve individual cilia. Furthermore, D-OCT technology can be incorporated into endoscopic platforms that allow clinicians to readily measure CBF in the office and provide a direct measurement of mucosal health.
authors.affiliation: Beckman Laser Institute, University of California-Irvine, Irvine, CA.
authors.forename: Bryan T
authors.initials: BT
authors.lastname: Lemieux
authors.affiliation: Beckman Laser Institute, University of California-Irvine, Irvine, CA.
authors.forename: Jason J
authors.initials: JJ
authors.lastname: Chen
authors.affiliation: Beckman Laser Institute, University of California-Irvine, Irvine, CA.|Department of Biomedical Engineering, University of California-Irvine, Irvine, CA.
authors.forename: Joseph
authors.initials: J
authors.lastname: Jing
authors.affiliation: Beckman Laser Institute, University of California-Irvine, Irvine, CA.|Department of Biomedical Engineering, University of California-Irvine, Irvine, CA.
authors.forename: Zhongping
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Beckman Laser Institute, University of California-Irvine, Irvine, CA.|Department of Biomedical Engineering, University of California-Irvine, Irvine, CA.|Department of Otolaryngology-Head and Neck Surgery, University of California-Irvine, Irvine, CA.
authors.forename: Brian J F
authors.initials: BJ
authors.lastname: Wong
mesh_terms: D000818:Animals; D002923:Cilia / Q000378:metabolism* / Q000473:pathology; D004301:Doppler Effect; D006801:Humans; D008297:Male; D009079:Mucociliary Clearance; D009297:Nasal Mucosa / Q000000981:diagnostic imaging / Q000473:pathology*; D011817:Rabbits; D011859:Radiography; D012984:Software; D041623:Tomography, Optical Coherence / Q000379:methods*
keywords: Fourier analysis; cilia; ciliary motility disorders; epithelial cells; fiber optic technology; mucociliary clearance; mucous membrane; nasal mucosa; optical coherence tomography; respiratory mucosa