Comparison of 129Xe MRI With 19F MRI in CF Lung Disease

Inclusion Criteria: Subjects with CF must meet all of the following inclusion criteria to be eligible for enrollment: 1. Subjects must be at least 18 years of age; 2. Non-smokers (\<10 pack year history and no active smoking in the past year); 3. Diagnosis of cystic fibrosis as via standard sweat chloride/phenotypic features/genotyping 4. Stable lung disease as evidenced by no change in respiratory medications or change in forced expiratory volume in 1 second (FEV1) of \>15% from baseline over the preceding 4 weeks prior to enrollment 5. Baseline FEV1 \>70% of predicted. 6. No use of supplemental oxygen 7. Evidence of a personally signed and dated informed consent document indicating that the subject has been informed of all pertinent aspects of the trial 8. Subjects must be willing and able to comply with scheduled visits and other trial procedures. Subjects without CF must meet all of the following inclusion criteria to be eligible for enrollment: 1. Subjects must be at least 18 years of age; 2. Non-smokers (\<10 pack year history and no active smoking in the past year); 3. Baseline FEV1 \>70% of predicted. 4. No use of supplemental oxygen or clinically significant lung disease 5. Evidence of a personally signed and dated informed consent document indicating that the subject has been informed of all pertinent aspects of the trial 6. Subjects must be willing and able to comply with scheduled visits and other trial procedures. Exclusion Criteria: 1. Active or past smokers with less than 1 years since quitting or \>10 pack-year smoking history 2. Co-existent asthma (as evidenced by either clinical diagnosis, chronic oral steroid use, or marked broncho-reactivity on pulmonary function testing) 3. Unable to undergo a 3.0-Tesla MRI exam of the lungs and chest because of contraindications including * Occupation (past or present) of machinist, welder, grinder; * Injury to the eye involving a metallic object * Injury to the body by a metallic object (bullet, BB, shrapnel) * Presence of a cardiac pacemaker or defibrillator * Presence of aneurysm clips * Presence of carotid artery vascular clamp * Presence of neurostimulator * Presence of insulin or infusion pump * Presence of implanted drug infusion device that is not known to be MRI compatible (i.e., was placed outside of UNCH or is older than 10 years) * Bone growth or fusion simulator * Presence of cochlear, otologic or ear implant * Any type of prosthesis (eye, penile, etc.) * Artificial limb or joint * Non-removable electrodes (on body, head or brain) * Intravascular stents, filters or coils * Shunt (spinal or intraventricular) * Swan-ganz catheter * Any implant held in place by a magnet * Transdermal delivery system (e.g. Nitro) * Intrauterine Device (IUD) or diaphragm * Tattooed makeup (eyeliner, lips, etc.) or tattoos covering \>25% of body surface area * Body piercings (MUST BE REMOVED BEFORE MRI) * Any metal fragments * Internal pacing wires * Metal or wire mesh implants * Hearing aid (REMOVE BEFORE MRI) * Dentures (REMOVE BEFORE MRI) * Claustrophobia 4. Unable to tolerate inhalation of gas mixture 5. Any changes in medications that may affect CF lung disease in the past 14 days, including any experimental therapies 6. Other severe acute or chronic medical or psychiatric condition or laboratory abnormality that may increase the risk associated with trial participation or may interfere with the interpretation of trial results and, in the judgment of the investigator, would make the subject inappropriate for entry into this trial. 7. Pregnancy; women of childbearing potential must have a confirmed negative urine pregnancy test on the day of the MRI scan, prior to the MRI scan.