The purpose of this study is to determine if 18Fluorodeoxyglucose (FDG) Positron Emission Tomography (PET) imaging can detect changes in airways inflammation in Cystic Fibrosis (CF) patients after treatment for a pulmonary exacerbation.

Neutrophils play a key role in the pathogenesis of CF lung disease. We know that neutrophilic inflammation is related to a decline in pulmonary function. Therefore, early anti-inflammatory intervention is an opportunity to slow this irreversible pulmonary destruction. However, the development of sensitive, non-invasive diagnostic tools of airways inflammation is essential to the study and implementation of anti-inflammatory therapies. Our current armentarium of measures of airways inflammation is limited. BAL is invasive and not clinically acceptable as a tool for the serial measurement of inflammation. Sputum samples are highly variable and not reliable.

18FDG-PET is a promising tool because it is non invasive, has been shown to quantify the amount and location of neutrophilic inflammation and has the potential to be used to track inflammation over time. Therefore, the goal of this research study is to evaluate the ability of 18FDG -PET imaging to detect changes in airways inflammation in CF patients in response to conventional treatment for a pulmonary exacerbation

Inclusion Criteria:

• Diagnosis of CF as defined by two or more clinical features of CF and a documented sweat chloride > 60mEq/L by quantitative pilocarpine iontophoresis test or a genotype showing two well characterized disease causing mutations
• Informed consent and verbal assent (as appropriate) provided by the subject's parent or legal guardian and the subject
• Ages 6-18 and able to perform reproducible spirometry
• Admission to the Hospital for Sick Children for a pulmonary exacerbation

Exclusion Criteria:

• Inability to perform reproducible spirometry
• Diagnosis of Cystic Fibrosis Related Diabetes (CFRD)
• Medical instability that would preclude the ability to perform PET imaging
• FEV1% predicted < 40%
• The use of supplementary oxygen
• Pregnancy or breastfeeding
• Severe claustrophobia