Fourier-decomposition of free-breathing pulmonary proton MRI in asthma

Introduction: Recently, inhaled gas MRI measurements of ventilation heterogeneity were evaluated in severe asthmatics and were shown to explain severity and control. These results have motivated the development of 1 H MRI acquisition and analysis methods for ventilation measurement using Fourier-decomposition 1 H MRI (FDMRI). Here our objective was to compare ventilation using FDMRI and inhaled gas MRI in asthma. We hypothesized that ventilation would be qualitatively/quantitatively similar using both methods. Methods: Twenty severe asthmatics (49±11yrs) provided written informed consent to perform pulmonary function tests, multiple breath washout, and MRI (3T MR750). Relationships were determined with spearman correlations (ρ) using Graphpad Prism V7.00. Results: Figure 1 shows 3 He and FDMRI ventilation maps for representative asthmatics. There was spatial agreement for ventilation defects for the subject with abnormal LCI. FDMRI ventilation defect percent (VDP) was correlated with 3 He VDP (ρ=.61, p=.01) and LCI (ρ=.54, p=.01). Conclusions: In this proof-of-concept study, we generated FDMRI in 20 asthmatics to visualize and measure ventilation abnormalities that were related to those present in noble gas MRI. Moreover, FDMRI ventilation defects were also related to other clinical measurements of ventilation heterogeneity. These data are promising and driving our development of 3D whole lung FDMRI. Figure 1. Ventilation MRI of asthmatic patients.