This study is being done to determine whether MRI can produce high quality lung and airway images in healthy and CF patients and if MRI can be used to evaluate size and shape of the airways with computer assistance. This study will also repeat MRI experiments two years after the initial MRI scan to see if changes to airway size and shape are seen over time. In a subset of participants, we will investigate whether MRI results are repeatable and reproducible in the short-term one week after the initial MRI visit. This study will help understand if MRI based measurements of airway size and shape can be used as a monitoring tool that does not use x-ray radiation in patients with CF.

Early CF disease in the lungs is characterized by repeated infection which can alter dimensions of the airways , especially abnormal dilation of the airways (bronchiectasis) Airway tree mapping is a form of quantitative imaging that investigates segmentation and dimensionality of the upper airways. CT detects utilized to characterize airway dimension in adults with COPD, but involves ionizing radiation. Unexplored in children.

MRI: Non-invasive, radiation-free, ideal for longitudinal monitoring. However, struggles with lung imaging due to low signal intensity, short T2 relaxation times, and motion artifacts Advanced ultrashort echo time (UTE) MRI enables high-resolution airway imaging with motion correction for free-breathing airway imaging. May permit airway tree mapping in children while obviating ionizing radiation risk.

Group 1

Inclusion Criteria:

• Participants must be greater than or equal to 6 years of age and not greater than 18 years of age.
• Informed consent by patient or parent/guardian consent and participant assent when appropriate.
• Able to perform reproducible spirometry

Exclusion Criteria:

• Medical instability that would preclude the ability to undergo the required investigations
• FEV1 % predicted < 40%
• Severe claustrophobia
• Does not meet MRI screening criteria
• Usage of oral antibiotics within 3 weeks prior to study visit
• Known pulmonary disease

Group 2 Inclusion Criteria

• Diagnosis of CF as evidenced by one or more clinical feature consistent with the CF phenotype or positive CF newborn screen
• Participants must be greater than or equal to 6 years of age and not greater than 18 years of age.
• Informed consent by patient or parent/guardian consent and participant assent when appropriate.
• Able to perform reproducible spirometry

Exclusion Criteria

• Medical instability that would preclude the ability to undergo the required investigations
• FEV1 % predicted < 40%
• Severe claustrophobia
• Does not meet MRI screening criteria
• Worsening cough and/or sputum production within the past 3 days prior to study visit
• The use of new oral and/or inhaled antibiotics within 3 weeks prior to study visit
• Received intravenous antibiotics within 2 weeks prior to study visit
• The use of supplementary oxygen
• Status of post lung or another organ transplant

Study conducted at The Hospital for Sick Children in Toronto, Canada. CF participants recruited through clinic. Controls selected from general population.