Assessment of the pulmonary distribution of atomized surfactant using MRI: an in vivo comparison with the clinical reference method using surfactant instillation.

Respiratory distress syndrome (RDS) in preterm infants occurs from surfactant deficiency. While less invasive surfactant administration (LISA) improves outcomes, the procedure remains traumatic. Atomized surfactant delivery offers a promising, less invasive alternative with the potential for improved distribution. MRI was used in a rabbit model to compare the pulmonary distribution of atomized surfactant with standard LISA instillation. Six-week-old female New Zealand rabbits (1.2 kg) received MRI contrast enhanced surfactant via either LISA (n = 6) or an atomizer device (n = 7). MRI was performed 10 min post-administration, yielding 3D isotropic 1-mm resolution images. MRI captured contrast-enhanced surfactant distribution in both groups, with signal enhancement restricted to peripheral lung regions. Contrast-enhanced regions and total lung volume were segmented, and surfactant concentration maps were generated. Quantitative analysis revealed comparable total surfactant doses delivered by both techniques, with total lung gadolinium content of 38 ± 28 µmol (LISA) and 36 ± 18 µmol (atomizer). However, the fraction of contrast-enhanced lung volume was significantly higher with the atomizer (46 ± 8% vs 55 ± 6%, p < 0.05). Laterality and distality of surfactant distribution were assessed. Both groups exhibited a slight right lung predominance in surfactant distribution. Notably, the distality was increased following atomized delivery (4.0 ± 0.3 mm vs. 4.3 ± 0.3 mm, p < 0.05), indicating more distal surfactant distribution. MRI results indicate that this device performs better in terms of volume of distribution and distal extent. More generally, the MRI methodology used in this study provides a foundation for optimizing surfactant administration strategies in neonatal care.