Feasibility of lung imaging at 0.55T for assessment of interstitial lung disease in patients with pulmonary sarcoidosis

OBJECTIVES: To assess the feasibility and diagnostic performance of radiation-free 0.55-T lung MRI for pulmonary sarcoidosis, combining morphological imaging with functional proton MRI ventilation/perfusion metrics, and to explore correlations with pulmonary function testing (PFT). MATERIALS AND METHODS: In this prospective study, 15 patients with pulmonary sarcoidosis and 30 healthy volunteers underwent 0.55-T lung MRI (bSTAR morphology; matrix-pencil based functional proton MRI). CT served as the reference standard for morphological findings (majority vote of experienced readers). Functional maps yielded ventilation defect percentage (VDP), perfusion defect percentage (QDP), and ventilation-perfusion overlap (VQO); thresholds were derived from the healthy cohort. Group comparisons and correlations with PFT were performed. RESULTS: MRI achieved the highest sensitivity for consolidations (86%) and moderate performance for nodules (67%) as well as ground-glass opacities (70%), but lower sensitivity for reticulations (29%) and traction bronchiectases (27%) compared with CT. Inter-reader and inter-modality agreement were moderate. Functional MP-MRI revealed significantly higher VDP, QDP, and VQO in patients compared with volunteers (all p < 0.01). Strong correlations were found between MRI-derived VDP and RV/TLC ratio (r = 0.90, p < 0.001) and between QDP and FEV1 (r = 0.63, p = 0.01). CONCLUSION: Low-field lung MRI provides complementary information in pulmonary sarcoidosis, enabling structural assessment free of ionizing radiation, with overall moderate agreement compared to CT, and adds valuable regional lung function analysis correlated with PFT. KEY POINTS: Question Can 0.55-T lung MRI supplement CT in pulmonary sarcoidosis by providing structural assessment plus regional ventilation and perfusion metrics linked to pulmonary function? Findings 0.55-T MRI showed high sensitivity for consolidations (86%) and revealed increased ventilation and perfusion defects that correlated strongly with the residual volume-to-total lung capacity ratio. Clinical relevance Low-field lung MRI enables radiation-free assessment of structural and functional lung involvement, offering additional regional information that may support longitudinal monitoring in selected patients with pulmonary sarcoidosis.