The goal of this study is to evaluate the usefulness of hyperpolarized (HP) 129Xe (xenon) gas MRI for regional assessment of lung function in a normal population of children and adults and in adults and also in children with respiratory compromise due to a variety of diseases.

Hyperpolarized 129Xe will be produced, by trained staff, using a polarizer housed at Cincinnati Children's Hospital Medical Center. Individual imaging sessions will be done on a single day and will involve administration of (maximum) 1 liter doses (less for children) for up to four MRI scans. Subject will inhale hyperpolarized xenon gas and hold breath for up to 16 seconds during the MRI scans. In addition to 129 Xe MRI, a series of anatomical conventional proton MR images may also be collected. Follow up phone calls will be done one day and 30 days from the MRI date.

Inclusion Criteria:

• Ages 6 and up
• Participant must be able to hold breath for up to 16 seconds

Exclusion Criteria:

• History of heart defect
• Pregnancy or positive pregnancy test
• History of uncontrolled asthma defined for this study as requiring use of rescue inhaler ≥ 2 times in past month
• Symptoms of respiratory infection (loose or productive cough or wheeze), chest tightness, or sinus infection within past week
• Baseline oximetry at MRI visit of less than 95% on room air or less than 95% on a previously prescribed dosage of oxygen delivered by nasal cannula
• Participant is claustrophobic and unable to tolerate the imaging.
• Standard MRI exclusions (metal, implants)