Defined as a need for oxygen at 36 weeks' postmenstrual age,2 BPD results in longterm morbidity in children and adults, including reduced lung function, early cardiovascular disease and premature death The reported severity of such impairments varies, as studies have been conducted on small numbers of children with differing degrees of prematurity. Furthermore, it is unclear what markers are most sensitive to predict long-term respiratory compromise. While functional measures have been studied, micro-structural differences, that may be quantified using pulmonary magnetic resonance imaging (MRI), have not been evaluated in this population, and may provide earlier quantitative markers of future respiratory disease, including chronic obstructive pulmonary disease (COPD). Recent advances in the clinical care of preterm infants have permitted survival of ever more premature infants, in whom alveolar development is incomplete, representing a new, relatively unstudied and growing cohort with a new form of BPD.