The purpose of this study is to determine the ability of electrical impedance tomography (EIT) to identify structural and functional physiological changes that occur with disease progression in cystic fibrosis patients. The investigators also aim to determine whether EIT can serve as an alternative for CT to identify regions of air trapping and consolidation, whether EIT can provide clinically useful information about response to treatment for an acute PE, and whether EIT can provide longitudinal information about structural changes in the lung.

Inclusion Criteria:

Cohort 1:

• Age 3-21 years
• Male or female
• Healthy subjects with no known or suspected chronic or temporary lung disease

Cohort 2:

• Age 3-21 years
• Male or female
• CF as diagnosed based on sweat chloride value(>60 mmol/L) or two known disease causing mutations

Cohort 3:

• Age 3-21 years
• Male or female
• CF as diagnosed based on sweat chloride value (>60 mmol/L) or two known disease causing mutations
• Experiencing a protocol defined pulmonary exacerbation and being started on oral or intravenous antibiotics

Exclusion Criteria:

• Unwilling/refusal to sign consent
• Known congenital heart disease, arrhythmia, or history of heart failure
• Wearing a pacemaker or a metallic surgical implant in the chest
• History of infection with Burkholderia cepacia
• Developmental delays that could result in an inability to complete study procedures

Children and young adults between 3 and 21 years old, with or without cystic fibrosis