Clinical value of measurement of pulmonary radioaerosol mucociliary clearance in the work up of primary ciliary dyskinesia

Background: We aimed to evaluate and define the general clinical applicability and impact of pulmonary radioaerosol mucociliary clearance (PRMC) on the work up of patients suspected of having primary ciliary dyskinesia (PCD). In addition, we wanted to evaluate the accuracy of the reference values used in the PRMC test. Methods: Measurement of PRMC after inhalation of Tc-99m-albumin colloid aerosol was carried out on 239 patients (4-75 years of age) during a 9-year period. All were referred to the nuclear medicine department because of clinical suspicion of PCD. The results were compared primarily to results from nasal ciliary function testing, to electron microscopic (EM) examination of the ultrastructure of the cilia, and to the final clinical diagnosis. Results: Of the 239 patients, 27 ended up with a final clinical diagnosis of definitive PCD. No patients with a PRMC test that was normal or otherwise not consistent with PCD ended up with PCD as final clinical diagnosis (though a minority of patients in this group ended up unresolved in regard to PCD). Forty percent of patients with an abnormal PRMC test ended up with PCD as final clinical diagnosis. Furthermore, the PRMC test had a high rate of conclusive results (90 %). Children <14 years of age with normal PRMC measurements showed significantly faster lung clearance than adults with similarly normal PRMC measurements. Conclusions: To this date, PRMC is the only test providing evaluation of the mucociliary clearance of the entire lung. Its greatest strength is its ability to reject a suspected PCD diagnosis with great certainty. In our material, this accounted for 2/3 of referred patients. In addition, the test has a high rate of conclusive results. According to our analyses, reference equations on children would benefit from updated data.