Phase-resolved functional lung magnetic resonance imaging for evaluation of lung perfusion and ventilation in fibrosing interstitial lung diseases

OBJECTIVE: The pathophysiological changes of lung perfusion and ventilation in fibrosing interstitial lung diseases (F-ILD) remain inadequately characterized. This study aimed to analyze lung perfusion and ventilation characteristics in F-ILD patients using phase-resolved functional lung magnetic resonance imaging (PREFUL MRI) as well as their correlation with the severity of F-ILD. MATERIALS AND METHODS: This cross-sectional study prospectively included 30 patients diagnosed with F-ILD (19 males, 64.6 ± 9.5 years) and 30 age- and sex-matched normal controls. All participants underwent PREFUL MRI as well as pulmonary function tests. High-resolution CT (HRCT) was performed for the patient cohort. Ventilation and perfusion-related parameters obtained from PREFUL MRI were analyzed and correlated with PFTs and fibrotic lesions identified on HRCT. RESULTS: Compared with normal controls, F-ILD patients showed significant differences in mean perfusion (7.55% vs 4.60%), Mean Ventilation (13.95% vs 18.65%), Perfusion Defect (QDPexclusive) (3.65% vs 15.50%), ventilation-perfusion matched non-defect percentage (VQMnon-defect) (87.55% vs 70.10%), and ventilation-perfusion matched defect percentage (VQMdefect) (0.15% vs 1.35%) (all p < 0.05). Mean perfusion correlated positively with DLCO SB (single breath) %pred (ρ = 0.682, p < 0.001) and DLCO/VA (alveolar volume) %pred (ρ = 0.634, p < 0.001), while QDPexclusive correlated negatively with these parameters. Mean perfusion showed negative correlations with honeycombing, fibrotic lesions, and total interstitial lesion burden on HRCT, whereas QDPexclusive correlated positively with these abnormalities (all p < 0.05). CONCLUSION: PREFUL MRI provides a quantitative functional evaluation of ventilation and perfusion in F-ILD patients, demonstrating strong correlations with pulmonary function parameters and fibrotic lesions. It shows potential as a valuable monitoring tool enabling severity assessment of F-ILD. CRITICAL RELEVANCE STATEMENT: PREFUL MRI provides a non-invasive, free-radiation method in the assessment of ventilation and perfusion in F-ILD, enabling severity evaluation. KEY POINTS: In patients with F-ILD, lung perfusion decreased, and ventilation increased. Lung ventilation and perfusion correlated with lung function parameters in F-ILD; however, they are similar between idiopathic pulmonary fibrosis (IPF) and other types of F-ILD. After controlling demographics, PREFUL MRI perfusion parameters (mean perfusion and QDPexclusive) remain significant, independent predictors of gas-exchange capacity and fibrotic burden.