Ciliary Videomicroscopy: A Long Beat from the European Respiratory Society Guidelines to the Recognition as a Confirmatory Test for Primary Ciliary Dyskinesia

Abstract

Primary ciliary dyskinesia (PCD) is a rare inherited ciliopathy in which respiratory cilia are stationary or dyskinetic. The clinical presentation of PCD is highly non-specific since it includes infections and disorders of the upper (otitis and rhinosinusitis) and lower (neonatal respiratory distress, bronchitis, pneumonia and bronchiectasis) airways, starting in early life. Clinical examination alone does not allow a PCD diagnosis, which relies on several concordant tests, since none are sensitive or specific enough alone. Despite being the most sensitive and specific test to diagnose PCD, digital high-speed videomicroscopy (DHSV) is not sufficiently standardized, preventing its use with complete confidence as a confirmatory diagnostic test for PCD, or its inclusion in a diagnostic algorithm. Since the 2017 ERS recommendations for PCD diagnosis, three main issues remain to be solved in order to optimize DHSV ciliary beating evaluation: the problem in defining an accurate sensitivity and specificity as there is no gold standard method to diagnose all PCD cases, a lack of standardization in the operating procedure for processing respiratory samples, and in the choice of measured parameters (self-operating or not). The development of new automated analysis approaches is promising and will require full clinical validation.

Quantifying cilia beat frequency using high‐speed video microscopy: Assessing frame rate requirements when imaging different ciliated tissues

“…Mateos-Quiros et al, 2021;Mikhailik et al, 2021;Reula et al, 2021;Smith et al, 2012;Zahid et al, 2020). The lack of a standardized fps for imaging motile cilia is especially problematic because it hinders high-speed video microscopy from being clinically adapted as a diagnostic tool to help uncover motile cilia diseases, such as primary ciliary dyskinesia (Bricmont et al, 2021;Shapiro et al, 2018). The large disparity in frame rates used to image cilia motility is partly technology dependant, with early studies generally being restricted to lower fps imaging technology (2-25 Hz) (Clary-Meinesz et al, 1992;Hennessy et al, 1986), while more recent studies with access to much faster and cheaper imaging technology generally having higher fps (≥500 fps) (Smith et al, 2012;Yasuda et al, 2020).…”

“…However, no standardized frame rate exists when imaging cilia motility for subsequent CBF calculation, this has resulted in a large range of frames rates used to image cilia motility within the published literature (Abdelhamed et al, 2018 ; Abdelhamed et al, 2020 ; Bustamante‐Marin et al, 2019 ; Chen et al, 2016 ; Hagiwara et al, 2020 ; Hennessy et al, 1986 ; Liu et al, 2021 ; Mateos‐Quiros et al, 2021 ; Mikhailik et al, 2021 ; Reula et al, 2021 ; Smith et al, 2012 ; Zahid et al, 2020 ). The lack of a standardized fps for imaging motile cilia is especially problematic because it hinders high‐speed video microscopy from being clinically adapted as a diagnostic tool to help uncover motile cilia diseases, such as primary ciliary dyskinesia (Bricmont et al, 2021 ; Shapiro et al, 2018 ). The large disparity in frame rates used to image cilia motility is partly technology dependant, with early studies generally being restricted to lower fps imaging technology (2–25 Hz) (Clary‐Meinesz et al, 1992 ; Hennessy et al, 1986 ), while more recent studies with access to much faster and cheaper imaging technology generally having higher fps (≥500 fps) (Smith et al, 2012 ; Yasuda et al, 2020 ).…”

“…The large variation in sampling rates suggests some studies may be under‐sampling or oversampling cilia motility, which could result in inaccurate quantification of CBF or generation of large volumes of oversampled data requiring analysis and storage. The lack of a standardized motile cilia imaging protocol is problematic because it hinders high‐speed video microscopy from being clinically adapted as a diagnostic tool to help detect motile cilia diseases, such as primary ciliary dyskinesia (Bricmont et al, 2021 ; Shapiro et al, 2018 ).…”

The RSPH4A Gene in Primary Ciliary Dyskinesia

“…HSVA is a technique that uses light microscopy to observe respiratory cilia ex vivo and a high-speed video camera to record them [46]. Ciliary beat frequency (CBF), ciliary beat pattern (CBP), and effective mucociliary clearance are all measured in recorded videos [47]. As a diagnostic tool, HSVA allows the ciliary function to be tested on the same day [48].…”

The Cilialyzer – a freely available open-source software for a standardised identification of impaired mucociliary activity facilitating the diagnostic testing for PCD

“…The CBF is the only quantitative observable being routinely determined in diagnostic centers. Even though the conventional HSVM approach is commonly considered as the most sensitive and specific test to identify PCD, its lack of standardisation prevents its use as a confirmatory diagnostic test, or its inclusion in a diagnostic algorithm [5].…”