Pulmonary disease in Cystic Fibrosis (CF) is characterized by progressive loss of functional gas exchange units that eventually results in respiratory failure. In CF lung disease,deling of pulmonary blood vessels, and vascular growth of bronchial blood vessels leadingystemic vascularization of the lung are the principal characteristics of pulmonary vascular disease. Studies have demonstrated that abnormal perfusion is present in up to 85%1 year old CF infants and only 17% of the perfusion deficits could be explained by mucusugging or bronchial wall abnormalities at this age. Based on the investigators' state ofhe art method to reconstruct the pulmonary vasculature from non-contrast high resolution CThe lungs, the investigators demonstrated that the blood volume in small vessels begins to decline when lung function is still in the normal range and worsens with increase disease severity. Furthermore, the investigators have also demonstrated that systemic vascularization of the lungs by the bronchial circulation begins at a FEV1% of 100. Preclinical studies of pulmonary endothelium revealed that delivering vascular endothelial growth factor receptor (VEGFR) antagonist to rats leads to air space enlargement and pruninghe pulmonary arterial tree. Thus, there is a central unanswered question as to whetherulmonary vascular disease (vascular remodeling and systemic vascularization) are just aqueal of parenchymal destruction or whether they contribute to the loss of alveolar gashange units and decline in lung function. In this proposal, the investigators willh the following aims: 1) describe the morphology of the pulmonary vasculature acrosswide range of lung function and relate the findings to functional outcomes, 2) examinehanism of early loss of small blood vessels in CF patients as it relates to endothelial CFTR dysfunction. In addition, the investigators will study the changes in the pulmonaryulation after the initiation of triple combination therapy Trikafta (elexacaftor,vacaftor, and tezacaftor).

This is a case control study of 93 cystic fibrosis patients and 100 age and gender matched. CF patients (cases) will be recruited from two cystic fibrosis centers, Cincinnati Children's Hospital and Riley Children's Hospital. Controls will be subjects from thegy service without lung disease who had CT scan of the chest to rule out pulmonary. 31 subjects of the 93 subjects enrolled will receive a second evaluation 6 monthsg a clinically prescribed corrector / modulator of Cystic Fibrosis Transmembrane Conductance Protein Regulator (Trikafta) that was approved by the FDA in October, 2019 forwith CF ages 12 and up. If FDA approval for use of Trikafta for ages 6-11 years ofge is obtained, this patient age range will also be eligible for the second evaluation at 6hs.