Objective: 1) In 7-9 year-old children born extremely premature, lung MRI will be compared between those with and without BPD. The Investigators expect to observe more severe structural lung abnormalities in children with BPD, compared to those without BPD; 2) The Investigators will test to see if children with more severe MRI abnormalities also have worse lung function, and/or more symptoms of breathing problems. The Investigators expect to observe more PFT abnormalities in children with BPD than in those without and that these will match up with lung fine structure abnormalities identified on MRI.