With hyperpolarized helium-3 (3He) MRI regional differences in airflow heterogeneity can be assessed. In this study, we used weighted entropy to evaluate dynamic ventilation heterogeneity in asthmatics. Serial 3He/1H scans were co-registered and normalized for comparison. Weighted entropy was calculated based on entropy and Ventilation defect percentage (VDP) values derived from normalized 3He scans. Lobar analysis was performed to identify lobar weighted entropy. We found that asthmatics have more heterogeneous ventilation distribution in the lower lobes at baseline. Variable airflow heterogeneity changes were observed globally in asthmatics, with the most significant bronchodilator response in the left lung.
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