Oxygen-enhanced MRI vs. quantitatively assessed thin-section CT: Pulmonary functional loss assessment and clinical stage classification of asthmatics

Purpose: The purpose of this study was to prospectively compare the efficacy of oxygen-enhanced MR imaging (O₂-enhanced MRI) and CT for pulmonary functional loss assessment and clinical stage classification of asthmatics. Materials and methods: O₂-enhanced MRI, CT and %FEV ₁ measurement were used 34 consecutive asthmatics classified into four stages ('Mild Intermittent [n = 7]', 'Mild Persistent [n = 8], 'Moderate Persistent [n = 14]' and 'Severe Persistent [n = 5]'). Relative enhancement ratio maps for every subject were generated, and determine mean relative enhancement ratios (MRERs). Mean lung density (MLD) and the airway wall area (WA) corrected by body surface area (WA/BSA) were also measured on CT. To compare the efficacy of the two methods for pulmonary functional loss assessment, all indexes were correlated with %FEV₁. To determine the efficacy of the two methods for clinical stage classification, all parameters for the four clinical stages were statistically compared. Results: %FEV ₁ showed fair or moderate correlation with all parameters (0.15 ≤ r² ≤ 0.30, p < 0.05). WA, WA/BSA and MRER of the 'Severe Persistent' group were significantly larger than those of 'Mild Intermittent' and 'Mild Persistent' groups (p < 0.05), and MRER of the 'Moderate Persistent' group significantly lower than that of the 'Mild Intermittent' group (p < 0.05). Conclusion: O₂-enhanced MRI is as effective as CT for pulmonary functional loss assessment and clinical stage classification of asthmatics.