Image phenotyping of preterm-born children using hyperpolarised 129Xe lung MRI and multiple-breath washout

Rationale: Preterm birth is associated with low lung function in childhood, but little is known about the lung microstructure in childhood.

Objectives: We assessed the differential associations between the historical diagnosis of bronchopulmonary dysplasia (BPD) and current lung function phenotypes on lung ventilation and microstructure in preterm-born children using hyperpolarised 129Xe ventilation and diffusion-weighted MRI, and multiple breath washout (MBW).

Methods: Data were available from 63 children (aged 9-13 years) including 44 born preterm (≤34 weeks’ gestation) and 19 term-born controls (≥37 weeks’ gestation). Preterm-born children were classified, using spirometry, into prematurity-associated obstructive lung disease (POLD, FEV1<LLN, FEV1/FVC<LLN); prematurity-associated preserved ratio of impaired spirometry (pPRISm, FEV1<LLN, FEV1/FVC≥LLN); preterm- and term-born controls; and into those with and without BPD. Ventilation heterogeneity metrics were derived from 129Xe ventilation MRI and SF6 MBW. Alveolar microstructural dimensions were derived from 129Xe diffusion-weighted MRI.

Measurements and Results: 129Xe ventilation defect percentage and ventilation heterogeneity index were significantly increased in preterm-born children with POLD. In contrast, mean 129Xe apparent diffusion coefficient (ADC), 129Xe ADC interquartile range (IQR) and 129Xe mean alveolar dimension IQR were significantly increased in preterm-born children with BPD, suggesting changes of alveolar dimensions. MBW metrics were all significantly increased in the POLD group when compared to preterm- and term-born controls. Linear regression confirmed the differential effects of obstructive disease on ventilation defects and BPD on lung microstructure.

Conclusion: We show that ventilation abnormalities are associated with prematurity-associated obstructive lung disease, and BPD in infancy is associated with abnormal lung microstructure.