Initial feasibility and challenges of hyperpolarized 129 Xe MRI in neonates with bronchopulmonary dysplasia

Abstract

Purpose: The underlying functional and microstructural lung disease in neonates who are born preterm (bronchopulmonary dysplasia, BPD) remains poorly characterized. Moreover, there is a lack of suitable techniques to reliably assess lung function in this population. Here, we report our preliminary experience with hyperpolarized ¹²⁹ Xe MRI in neonates with BPD.

Methods: Neonatal intensive care patients with established BPD were recruited (N = 9) and imaged at a corrected gestational age of median:40.7 (range:37.1, 44.4) wk using a 1.5T neonatal scanner. 2D ¹²⁹ Xe ventilation and diffusion-weighted images and dissolved phase spectroscopy were acquired, alongside ¹ H 3D radial UTE. ¹²⁹ Xe images were acquired during a series of short apneic breath-holds (˜3 s). ¹ H UTE images were acquired during tidal breathing. Ventilation defects were manually identified and qualitatively compared to lung structures on UTE. ADCs were calculated on a voxel-wise basis. The signal ratio of the ¹²⁹ Xe red blood cell (RBC) and tissue membrane (M) resonances from spectroscopy was determined.

Results: Spiral-based ¹²⁹ Xe ventilation imaging showed good image quality and sufficient sensitivity to detect mild ventilation abnormalities in patients with BPD. ¹²⁹ Xe ADC values were elevated above that expected given healthy data in older children and adults (median:0.046 [range:0.041, 0.064] cm² s^-1 ); the highest value obtained from an extremely pre-term patient. ¹²⁹ Xe spectroscopy revealed a low RBC/M ratio (0.14 [0.06, 0.21]).

Conclusion: We have demonstrated initial feasibility of ¹²⁹ Xe lung MRI in neonates. With further data, the technique may help guide management of infant lung diseases in the neonatal period and beyond.

Keywords: bronchopulmonary dysplasia; hyperpolarized 129Xe; lung MRI; neonatal MRI.