Specific Aim 1. Determine if valid results of non-sedated MRI based assessments of liver stiffness and lipid content can be obtained in more than 90% of children and young adults with cystic fibrosis.

Specific Aim 2. Determine hepatic lipid content using the HepaFat sequence and liver stiffness using MRE. Investigators will compare the results obtained by MRI with PUSH study grayscale ultrasounds in CF patients with normal, heterogeneous, homogeneous or nodular (cirrhotic) pattern on ultrasound.

Specific Aim 3. Creation of an imaging core lab to centralize evaluation of MR imaging data, allow for remote image upload, electronic data storage, and remote image viewing/interpretation. This infrastructure will be utilized to standardize image post processing.

Specific Aim 4. Using the longitudinal PUSH study, determine if MRI based imaging improves discrimination of subjects at risk for progression to advanced CF liver disease (development of cirrhosis) compared to using US imaging alone

This proposal will be a cross sectional study of the current well-characterized PUSH cohort. Patients will receive an MRI at the time of their scheduled PUSH ultrasound. Ideally, the MRI will be performed the same day or a similar time point near liver ultrasound (+/-90 days, but Investigators will allow a larger window due to the slow progression of fibrosis).

Blinded radiology review of imaging sequences will be performed by a local study radiologist with central review performed by the Imaging Core. Analysis by the Imaging Core will include calculation of the liver stiffness, liver and spleen volume, and hepatic and lipid content for all MRI studies.

Inclusion Criteria:

1. Currently enrolled in longitudinal follow up in PUSH study at a site with MR elastography.

Exclusion Criteria:

1. Age under 6 years (all current patients at time of opening of this study will be greater than 6 years of age).
2. Internal appliance or hardware that is not compatible with MR.
3. Inability to obtain MRI within 6 months of US.
4. Inability to cooperate with MRI.

Children aged 3 through 12 years of age at time of enrollment diagnosed with Cystic Fibrosis and pancreatic insufficiency and enrolled in the CFLD PUSH longitudinal study.