Hyperpolarized (3) He and (129) Xe MRI: Differences in asthma before bronchodilation

TLDR: To compare hyperpolarized helium‐3 (3He) and xenon‐129 (129Xe) MRI in asthmatics before and after salbutamol inhalation, a parallel study of 3He and 129Xe is presented.

Abstract: Purpose To compare hyperpolarized helium-3 (3He) and xenon-129 (129Xe) MRI in asthmatics before and after salbutamol inhalation. Materials and Methods Seven asthmatics provided written informed consent and underwent spirometry, plethysmography, and MRI before and after salbutamol inhalation. 3He and 129Xe ventilation defect percent (VDP) and ventilation coefficient of variation (COV) were measured. To characterize the airways spatially related to ventilation defects, wall area percent (WA%) and lumen area (LA) were evaluated for two subjects who had thoracic x-ray computed tomography (CT) acquired 1 year before MRI. Results Before salbutamol inhalation, 129Xe VDP (8 ± 5%) was significantly greater than 3He VDP (6 ± 5%, P = 0.003). Post-salbutamol, there was a significant improvement in both 129Xe (5 ± 4%, P < 0.0001) and 3He (4 ± 3%, P = 0.001) VDP, and the improvement in 129Xe VDP was significantly greater (P = 0.008). 129Xe MRI COV (Pre: 0.309 ± 0.028, Post: 0.296 ± 0.036) was significantly greater than 3He MRI COV (Pre: 0.282 ± 0.018, Post: 0.269 ± 0.024), pre- (P < 0.0001) and post-salbutamol (P < 0.0001) and the decrease in COV post-salbutamol was significant (129Xe, P = 0.002; 3He, P < 0.0001). For a single asthmatic, a sub-segmental 129Xe MRI ventilation defect that was visible only before salbutamol inhalation but not visible using 3He MRI was spatially related to a remodeled fourth generation sub-segmental airway (WA% = 78%, LA = 2.9 mm2). Conclusion In asthma, hyperpolarized 129Xe MRI may help reveal ventilation abnormalities before bronchodilation that are not observed using hyperpolarized 3He MRI. J. Magn. Reson. Imaging 2013;38:1521–1530. © 2013 Wiley Periodicals, Inc.