Longitudinal Assessment of Transient Elastography in Cystic Fibrosis

To determine if transient elastography (TE), when combined with ultrasound (US) pattern characterization can improve the prediction of progression to a nodular pattern on US. To confirm the feasibility of obtaining TE measurements in children with Cystic Fibrosis (CF) To prospectively assess whether TE data are associated with conventional laboratory markers of hepatic fibrosis To determine the variability of TE measurements taken at different sites in the same patient