19F MRI of Ventilation in Subjects With Cystic Fibrosis Undergoing Treatment for Pulmonary Exacerbation

The investigators hypothesize that 19F-enhanced MRI will detect improvements in lung ventilation following the treatment of a CF pulmonary exacerbation, and changes in ventilation as well as global MRI scores will track with both spirometry and quality of life assessments. Therefore, investigators propose this pilot and feasibility study to gain preliminary data on a comparison of the changes in ventilation that occur with treatment of a pulmonary exacerbation, as well as to begin to understand the repeatability of this novel outcome measure. Through this study, the investigators aim to: 1) Compare quantitative and qualitative assessments of lung ventilation using 19F MRI imaging and traditional, global physiologic assessments (spirometry, LCI) and compare these with images obtained in an age-matched healthy control population; 2) Correlate changes in MRI scoring with subjective changes in health related outcomes as measured by the CFQ-R (Cystic Fibrosis Questionnaire - Revised); 3) Determine the ability of 19F MRI to detect changes in ventilation that occur with treatment of a CF pulmonary exacerbation; and 4) Determine the repeatability of 19F MRI assessment of ventilation in a disease population. Participants with CF with baseline forced expiratory volume in 1 second (FEV1) of at least 40%, no contraindications to MRI, and oxygen saturation \>90% on room air will be prospectively enrolled. Investigators will recruit a pre-defined cross-section of CF patients with mild, moderate, and severe lung disease, with approximately 4 subjects per group at the onset of a disease exacerbation requiring antibiotic intervention. The research team will obtain a pre-response MRI (within 3 days of initiating oral, inhaled, or IV antibiotic therapy), and a post-treatment MRI (within 3 days of terminating antibiotic treatment) to assess the responsiveness of 19F-MRI to a change in disease status. Each 19F-MRI study will be combined with assessments of spirometry, LCI (multiple breath nitrogen washout), and quality of life (CFQ-R quality of life tool). 19F-MRI will be performed by having each participant inhale a mixture of 79% perfluorinated propane (PFP) and 21% oxygen (pre-mixed) while using MRI to obtain 3D images. Subsequently, participants will be switched to room air, and cycled breathing will be continued while additional MRI images are captured to characterize gas wash-out. Safety measures, including pulse oximetry, will be monitored continuously, and spirometry will be performed before and after each MRI. Participants will also perform multiple breath washout maneuvers to obtain a lung clearance index, so this may be correlated to wash-out kinetics of the PFP.