Representative axial gradient echo (GRE) and ultrashort echo time (UTE) magnetic resonance imaging (MRI) demonstrating the range of bronchopulmonary dysplasia (BPD) severity. The level of respiratory support at neonatal ICU discharge and MRI scores are provided for each subject. Owing to its relatively short TE value, the UTE sequence can visualize hypodense tissue with intensity above the noise floor, whereas, in the same tissue, the GRE image is reconstructed with intensity near that of noise, even when non-zero density is present and apparent on UTE (for example, in the deceased severe BPD case at far right). In this way, UTE contrast weighting yields density-like intensities between various pulmonary tissues. On the other hand, with its relatively long TE value, the GRE sequence can yield improved contrast between fibrotic/interstitial/soft tissues and normal/hypodense parenchymal tissues, even though it does not represent accurate density measures of tissue with rapid effective transverse relaxation time decay.

Reprinted with permission from Am J Respir Crit Care Med. 2018 Nov 15; 198(10): 1302–1311. Higano et al. Neonatal Pulmonary Magnetic Resonance Imaging of Bronchopulmonary Dysplasia Predicts Short-Term Clinical Outcomes

Inhaled helium-3 gas diffusion MRI in ex-vivo infant lungs, compared with microstructural histology of alveolar airspaces. The two lung specimens shown include a left upper lobe from a 16-month-old healthy infant (left) and a left lung from an 11-month-old diseased infant with filamin-A gene mutation (right). Helium-3 gas MR images are shown in the top row, and apparent diffusion coefficient (ADC) maps for the corresponding image slices are shown in the middle row. ADC values are increased and have more regional heterogeneity in the diseased specimen than in the healthy specimen. This is indicative of abnormally enlarged alveolar airspaces, as confirmed via regionally matched quantitative histology (bottom row).

Reprinted with permission from Neonatology. 2020;117(6):704–712. Higano et al. Alveolar airspace size in healthy and diseased infant lungs measured via hyperpolarized 3He gas diffusion MRI

High-resolution 3D ultrashort echo-time MRI allows for sensitive detection of lung disease phenotypes associated with bronchopulmonary dysplasia in preterm infants. Obstructive lung disease can be identified via hyperinflation and intercostal bulging, while restrictive lung disease can be measured by the presence of fibro-inflammatory parenchymal abnormalities.

Figure courtesy of Nara Higano, PhD.