129Xe-MRI to assess regional airway clearance in children with primary ciliary dyskinesia

Children with Primary Ciliary Dyskinesia (PCD) use personalised airway clearance techniques (ACT), yet their effects on regional lung function are unknown. Children with PCD were imaged with ¹²⁹Xe Ventilation MRI pre, post and 4-hours post-ACT. Categorical ventilation assessment was used; image voxels were binned by signal intensity thresholds: high, normal, low, or ventilation defect (VDP). For treatment response we calculated; the proportion of pre-ACT defect that persisted (P-VD) and the proportion of lung volume changing to or from low ventilation or VDP (%change). Data presented as median (IQR) or mean [SD]. 24 children were assessed (13 male, age 7-17years, FEV1 z-score=-1.8 [1.6]). Most had visible defects pre-ACT, VDP=6.0 (13.4)%. Post-ACT, some had significant persistent defects, P-VD = 22.1 (39.4)%, and widespread ventilation changes were seen even in those with low pre-ACT VDP, %change = 59.9 (20.8)%, (Fig 1). P-VD and %change each correlated significantly with pre-ACT VDP (both r=0.8, p<0.001). Similar changes were seen 4-hours post-ACT; P-VD = 21.4 (35.4)%, %change = 59.1(17.8)%. ¹²⁹Xe Ventilation MRI provides novel insights into ACT response revealing widespread gross and subtle ventilation changes. Children with more advanced disease have high persistence of defects post-ACT. Post-ACT, children with PCD have widespread positive and negative ventilation re-distribution, possibly due to secretion movement. <fig><object-id>erj;64/suppl_68/OA4664/F1</object-id><object-id>F1</object-id><object-id>F1</object-id><graphic></graphic></fig>