Simultaneous 3D structural-functional assessment of pediatric lung using 0.55-T MRI: a feasibility study.

BACKGROUND: Pediatric pulmonary diseases are commonly evaluated with imaging that either involves ionizing radiation or that lacks regional functional information. PURPOSE: To evaluate the feasibility of simultaneous structural and functional lung assessment in pediatric participants without radiation, contrast administration, or breath-holding. MATERIALS AND METHODS: This retrospective study analyzed pediatric patients with pulmonary disease and healthy participants, who were recruited from August 2023 to December 2025 via convenience sampling and underwent awake lung MRI on wide-bore 0.55-T scanners. A prototype balanced steady-state free-precession sequence with a half-radial dual-echo readout (bSTAR) was acquired with free breathing. Respiratory-resolved 3-dimensional images were reconstructed for structural evaluation and quantitative ventilation mapping. Two pediatric radiologists independently scored image quality (robustness to motion and streak artifacts, and parenchymal signal) and the anatomic visibility of the airways and vessels using 4-point Likert scales. Interreader agreement of structural findings was evaluated using Cohen's κ. Ventilation defect percentage measured by bSTAR was compared with 2-dimensional phase-resolved functional lung (PREFUL) MRI using Pearson correlation and Bland-Altman analysis. RESULTS: Fourteen participants (median [range] age, 11 [6-16] years; 8 females) were scanned. Image quality scores ranged from 3.0 to 3.8 on Likert scales. All cases were diagnostically acceptable (artifact robustness scores ≥2), with consistent visualization of segmental airway walls and subsegmental vasculature. Structural findings, including consolidation, mucus plugging, ground-glass opacity, air trapping, bronchiectasis, and mosaic hypointensity, showed substantial interreader agreement (κ = 0.6-0.8). Ventilation defects measured by bSTAR correlated strongly with PREFUL (r = 0.81, P < .001), with 95% limits of agreement of -18% to 23%. CONCLUSION: Simultaneous structural-functional lung imaging in a single free-breathing acquisition was feasible in this cohort of older awake pediatric participants using 0.55-T MRI, with structural images suitable for evaluating major pulmonary findings and quantitative ventilation metrics correlating strongly with PREFUL.