Figure 1.

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.