B105-13 Standard 0.55 T Lung MRI in Unsedated Adolescents and Infants: A Feasibility Study

Abstract Rationale Lung MRI provides a radiation-free imaging alternative for pediatric patients. However, conventional high-field MRI is limited by low signal-to-noise ratio and susceptibility artifacts in the lung, restricting sequence options and image quality. Low-field (0.55 T) MRI has recently emerged as a promising solution. The significantly slower parenchyma signal decay and less pronounced susceptibility artifacts at low field strengths enable standard imaging sequences to produce diagnostically useful lung images 1,2. This study evaluated the feasibility of standard 0.55 T lung MRI in unsedated pediatric patients, from infants to adolescents, without the need for specialized sequences. Methods The study followed protocols approved by our Institutional Review Board. Five pediatric patients (aged 6 to 16, including graft-versus-host lung disease (n = 2), cystic fibrosis (n = 2), and bronchiectasis (n = 1)) were scanned awake, and four premature infants with grade-3 bronchopulmonary dysplasia (BPD) (PMA: 40-43 weeks, weight: 3.5-4.0 kg) were scanned under natural sleep. Lung structural imaging was performed on a commercial 0.55 T scanner (MAGNETOM Free.Max, Siemens Healthcare, Forchheim, Germany) using a standard T2-weighted turbo spin echo (T2-TSE) sequence with respiratory-triggered BLADE acquisition scheme. Sequence parameters: Flip angle = 130, TE/TR = 28/3400 ms, in-plane resolution = 1.1 x 1.1 mm2, slice thickness = 6 mm, scan time = 3 to 4 minutes depending on respiration rate. Results In the adolescent subgroup, image acquisition was successfully completed and well tolerated in all subjects, producing diagnostic-quality images with minimal motion artifacts. Both hyperintense findings (e.g., consolidation) and hypointense abnormalities (e.g., air trapping and mosaic “attenuation” patterns) were clearly depicted, confirmed by CT (Figure 1A). Although spatial resolution was lower than that of CT, the standard T2-TSE sequence enabled parenchyma assessment without radiation exposure. In the BPD subgroup, high-quality T2-TSE images were obtained in three cases, revealing characteristic findings such as fibrosis, consolidation, and cystic changes. One case demonstrated motion artifact, likely due to respiratory-triggering failure. Notably, parenchymal clarity appeared to correlate with respiratory outcomes at discharge (Figure 1B). Conclusion High-quality lung structural imaging with detailed parenchymal assessment can be achieved using standard, out-of-the-box MRI sequences on commercial 0.55 T systems and is well tolerated in unsedated pediatric patients. The reliance on readily available scanners and sequences indicates potential for broad clinical adoption, extending lung MRI beyond specialized research settings. Future improvements are needed for robust respiratory triggering in infant subjects. References: 1 Campbell-Washburn, et al. Radiology (2019). 2 Campbell-Washburn, et al. Radiology: Cardiothoracic Imaging (2021). This abstract is funded by: Keck School of Medicine of USC Dean’s Pilot Grant Program