FDG-PET Imaging in Young Cystic Fibrosis Patients

Our recent study in CF adults, supplemented by recent pre-clinical and clinical studies by our group suggests that labeled fluorodeoxyglocose-based positron emission tomography (FDG-PET) imaging may be a valuable quantitative biomarker of lung inflammation. The proposed study would validate our earlier findings, but in a younger patient population. The implications of such a test could be highly significant for both the testing of promising new anti-inflammatory agents and for patient management decisions. To capitalize on this exciting opportunity, the critical next step is to show that we can identify a cohort of young CF patients with both stable lung function and normal (or near normal) FDG-PET imaging studies. Similar patients, then, would become the subjects for a future prospective cohort study to determine if FDG-PET imaging can in fact serve as a predictor of future changes in lung function.

Inclusion criteria

• Confirmed diagnosis of cystic fibrosis
• Age 12 to 21 years old, of either gender, any race or ethnicity
• Stable recent pulmonary status (defined as no new pulmonary symptoms, new antibiotic use, or hospitalization for pulmonary symptoms for at least 1 month).
• We will permit patients treated with the macrolide antibiotic, azithromycin, to participate in this study. Azithromycin has recently become a virtual standard of care in CF, based on small but reproducible improvements in pulmonary function over 4 months of treatment with this drug. The mechanism of benefit is uncertain, but an anti-inflammatory effect has been suggested. The high prevalence of use means that a study without azithromycin would likely require a wash-out period, without data about the appropriate duration for such a wash-out, or whether inflammatory markers would reverse during that time.

Exclusion criteria

• Failure to obtain informed consent
• Positive pregnancy test or lactation
• Currently enrolled in another study involving radioisotopes or an investigational drug
• Recent (within 30 days of screening) hospitalization for any reason
• New antibiotic use (within 30 days of screening).
• Patient incapable of lying still and supine within the PET/computed X-ray tomography (CT) scanner for 90 minutes.
• Patient incapable of completing other testing procedures (e.g., PFT, induced sputum)
• Patient with serum glucose greater than 150 mg/dl at time of PET imaging study
• Patient incapable of fasting for 4 to 6 hrs prior to PET imaging study