Assessing Mucociliary Clearance and Airway Liquid Volume in the CF Airway

Improper function of the mucociliary clearance system in the Cystic Fibrosis (CF) lung is a
major factor contributing to the chronic respiratory manifestations of the disease. Normally
this host defense mechanism removes inhaled pathogens and toxins from the inner surfaces of
the lung. In CF, mutations in the CF gene result in dysfunction of the Cystic Fibrosis
Transmembrane Conductance Regulator (CFTR) ion channel on the cells that line the airway
epithelium, causing improper fluxes of ions such as sodium, chloride, and bicarbonate. The so
called "low volume" hypothesis of CF pathogenesis contends that the liquid lining the airways
becomes very thin and viscous due to abnormal absorption of sodium from the airways, which
draws water out of the airways, partially or totally defeating mucociliary clearance. The
rate at which the mucociliary system clears materials from the lungs can be quantified using
a nuclear medicine test called a mucociliary clearance scan. This study pilots a new
variation of the mucociliary clearance scan that uses both "floating" and "penetrating"
radioisotope tags. The difference in clearance between these tags will provide information on
how airway surface liquid volume affects mucociliary clearance. This pilot trial will include
the imaging of n=5 CF subjects and n=5 healthy subjects.

Inclusion Criteria:

- Age ≥ 18 years

- Diagnosis of cystic fibrosis as determined by sweat test or genotype and clinical
symptoms (CF subjects only)

- Clinically stable as determined by the investigator (pulmonologist)

Exclusion Criteria:

- Reactive airways disease

- Tobacco smokers

- Positive urine pregnancy test on the day of testing

- FEV1p value of < 30%

- SaO2 < 92%, or if they require supplemental oxygen.

- Subjects receiving other radioisotope treatments within the last 2 weeks will be
excluded.

- Normal subjects with any history of lung disease will be excluded.

- Women currently breastfeeding an infant.