Infants admitted to the neonatal intensive care unit (NICU) often suffer from multifaceted pulmonary morbidities that are not well understood. Ultrashort echo time (UTE) magnetic resonance imaging (MRI) is a promising technique for pulmonary imaging in this population without requiring exposure to ionizing radiation. The aims of this study were to investigate the effect of neonatal pulmonary disease on R2* and tissue density and to utilize numerical simulations to evaluate the effect of different alveolar structures on predicted R2*.This was a prospective study, in which 17 neonatal human subjects (five control, seven with bronchopulmonary dysplasia [BPD], five with congenital diaphragmatic hernia [CDH]) were enrolled. Twelve subjects were male and five were female, with postmenstrual age (PMA) at MRI of 39.7 ± 4.7 weeks. A 1.5T/multiecho three‐dimensional UTE MRI was used. Pulmonary R2* and tissue density were compared across disease groups over the whole lung and regionally. A spherical shell alveolar model was used to predict the expected R2* over a range of tissue densities and tissue susceptibilities. Tests for significantly different mean R2* and tissue densities across disease groups were evaluated using analysis of variance, with subsequent pairwise group comparisons performed using t tests. Lung tissue density was lower in the ipsilateral lung in CDH compared to both controls and BPD patients (both p < 0.05), while only the contralateral lung in CDH (CDHc) had higher whole‐lung R2* than both controls and BPD (both p < 0.05). R2* differences were significant between controls and CDHc within all tissue density ranges (all p < 0.05) with the exception of the 80%–90% range (p = 0.17). Simulations predicted an inverse relationship between alveolar tissue density and R2* that matches empirical human data. Alveolar wall thickness had no effect on R2* independent of density (p = 1). The inverse relationship between R2* and tissue density is influenced by the presence of disease globally and regionally in neonates with BPD and CDH in the NICU.
Level of Evidence
2.
Technical Efficacy Stage
2.