Quantitative ^99mTc-albumin colloid nasal mucociliary clearance as an outcome in primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is an inherited disorder in which dyskinetic cilia cause impaired mucociliary clearance of upper and lower airways. Airway ciliary movement can be indirectly tested in vivo after administration of a radiolabelled tracer to the lower airways for assessment of pulmonary mucociliary clearance or to the nose for assessing nasal mucociliary clearance (NMC). With this study, we investigated NMC as a quantifiable study outcome parameter in patients with PCD.

This single centre proof-of-concept study on NMC velocity investigated patients with PCD across different genotypes and nasal nitric oxide (nasal NO) levels. Healthy controls were used for comparison. NMC was determined as velocity in mm·min^-1 of a nasally applied ^99mTc-albumin colloid tracer. Using a gamma camera, repeated dynamic series of images each lasting 30 s were acquired during a 10-minute period and digitally stored.

NMC velocity was investigated in seven patients with PCD (aged 9-31 years) and five adult healthy controls. Mean NMC velocity in healthy controls (8.5 mm·min^-1) was significantly higher compared with people with PCD (0.00 mm·min^-1, p<0.0001). NMC was completely absent in all included patients with PCD across different PCD genotypes and regardless of nasal NO values. The success rate of the test was 100% in both groups.

NMC velocity discriminated highly significantly between patients with PCD and healthy controls. We suggest here a fast and feasible set up for NMC measurements that is easily applicable for any clinical trial involving PCD medication aimed for the nasal compartment, a step before or parallel to conducting clinical trials investigating whole-lung ciliary function in PCD.