Time-series hyperpolarized xenon-129 MRI of lobar lung ventilation of COPD in comparison to V/Q-SPECT/CT and CT

PurposeTo derive lobar ventilation in patients with chronic obstructive pulmonary disease (COPD) using a rapid time-series hyperpolarized xenon-129 (HPX) magnetic resonance imaging (MRI) technique and compare this to ventilation/perfusion single-photon emission computed tomography (V/Q-SPECT), correlating the results with high-resolution computed tomography (CT) and pulmonary function tests (PFTs).Materials and methodsTwelve COPD subjects (GOLD stages I-IV) participated in this study and underwent HPX-MRI, V/Q-SPECT/CT, high-resolution CT, and PFTs. HPX-MRI was performed using a novel time-series spiral k-space sampling approach. Relative percentage ventilations were calculated for individual lobe for comparison to the relative SPECT lobar ventilation and perfusion. The absolute HPX-MRI percentage ventilation in each lobe was compared to the absolute CT percentage emphysema score calculated using a signal threshold method. Pearson's correlation and linear regression tests were performed to compare each imaging modality.ResultsStrong correlations were found between the relative lobar percentage ventilation with HPX-MRI and percentage ventilation SPECT (r=0.644; p<0.001) and percentage perfusion SPECT (r=0.767; p<0.001). The absolute CT percentage emphysema and HPX percentage ventilation correlation was also statistically significant (r=0.695, p<0.001). The whole lung HPX percentage ventilation correlated with the PFT measurements (FEV1 with r=-0.886, p<0.001*, and FEV1/FVC with r=-0.861, p<0.001*) better than the whole lung CT percentage emphysema score (FEV1 with r=-0.635, p=0.027; and FEV1/FVC with r=-0.652, p=0.021).ConclusionLobar ventilation with HPX-MRI showed a strong correlation with lobar ventilation and perfusion measurements derived from SPECT/CT, and is better than the emphysema score obtained with high-resolution CT.Key Points center dot The ventilation hyperpolarized xenon-129 MRI correlates well with ventilation and perfusion with SPECT/CT with the advantage of higher temporal and spatial resolution.center dot The hyperpolarized xenon-129 MRI correlates with the PFT measurements better than the high-resolution CT with the advantage of avoiding the use of ionizing radiation.