J Magn Reson Imaging

. 2021 Jan 6. doi: 10.1002/jmri.27487. Online ahead of print. https://pubmed.ncbi.nlm.nih.gov/33404085/

Effects of neonatal lung abnormalities on parenchymal R ₂ * estimates

Andrew D Hahn ¹, Annelise Malkus ¹, Jeffery Kammerman ¹, Nara Higano ², Laura L Walkup ^2 3, Jason Woods ^2 3, Sean B Fain ^1 4 5Affiliations expand

• PMID: 33404085
• DOI: 10.1002/jmri.27487

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Abstract

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.

Keywords: R2*; T2*; bronchopulmonary dysplasia; congenital diaphragmatic hernia; lung; neonatal magnetic resonance imaging.

© 2021 International Society for Magnetic Resonance in Medicine.