title: Aortopulmonary collateral flow in cystic fibrosis assessed with phase-contrast MRI.
abstract: BACKGROUND
  Cystic fibrosis (CF) is a common genetic disease in Caucasians. Chronic pulmonary disease with progressive destruction of the pulmonary parenchyma is two of the major morbidities, but the relationship between clinical severity of CF and aortopulmonary collateral blood flow has not been assessed.
  
  
  OBJECTIVE
  The purpose of this study is to measure changes in aortopulmonary collateral blood flow by phase-contrast magnetic resonance imaging (MRI) in children with CF across the spectrum of disease severity as measured by the forced expiratory volume in one second as percent predicted value (FEV1% predicted).
  
  
  METHODS
  Sixteen patients with CF were prospectively evaluated. Eight were classified as having mild CF lung disease (FEV1 ≥80% predicted) and eight were classified as having moderate to severe CF lung disease (FEV1 <80% predicted). Seventeen age- and gender-matched non-CF subjects without cardiac or lung disease served as controls. Phase-contrast flow was measured at the ascending aorta, main pulmonary artery and both pulmonary arteries. Aortopulmonary collateral blood flow was calculated for each subject. The relationship between collateral flow and FEV1% predicted was modeled using nonparametric regression. Group differences were assessed by analysis of variance.
  
  
  RESULTS
  Aortopulmonary collateral blood flow began to increase as FEV1% predicted in subjects with CF fell below 101.5% with significant further increase in the aortopulmonary collateral blood flow in the subjects with CF with moderate to severe lung disease compared to controls (0.89 vs. 0.20 L/min, P < 0.0001). Aortopulmonary collateral blood flow correlated negatively with FEV1% predicted (r=0.70, P = 0.0050) confirming its relationship to this established marker of disease severity. There was no statistically significant difference in results obtained from two independent observers.
  
  
  CONCLUSIONS
  These preliminary findings suggest that phase-contrast MRI can be performed reliably with consistent results and without interobserver variability. While the aortopulmonary collateral blood flow is within the normal range in subjects with mild CF disease, it begins to increase even when lung function is still in the normal range. A significant increase in the aortopulmonary collateral blood flow compared to controls is measured in patients with moderate to severe CF lung disease. The studies support the notion that aortopulmonary collateral blood flow may serve as a novel and sensitive biomarker of early pulmonary disease in cystic fibrosis.
authors.affiliation: Department of Pediatric Radiology, Cincinnati Children's Hospital - MLC 5031, 3333 Burnett Avenue, Cincinnati, OH, 45229, USA, Robert.Fleck@cchmc.org.
authors.forename: Robert
authors.initials: R
authors.lastname: Fleck
authors.forename: Gary
authors.initials: G
authors.lastname: McPhail
authors.forename: Rhonda
authors.initials: R
authors.lastname: Szczesniak
authors.forename: Joshua
authors.initials: J
authors.lastname: Knowlton
authors.forename: Rupa
authors.initials: R
authors.lastname: Radhakrishnan
authors.forename: John
authors.initials: J
authors.lastname: Clancy
authors.forename: Raouf
authors.initials: R
authors.lastname: Amin
mesh_terms: D000293:Adolescent; D001011:Aorta / Q000473:pathology / Q000503:physiopathology*; D001783:Blood Flow Velocity; D003097:Collateral Circulation; D003550:Cystic Fibrosis / Q000175:diagnosis* / Q000503:physiopathology*; D005260:Female; D006801:Humans; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D011651:Pulmonary Artery / Q000503:physiopathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity