Hyperpolarized ³helium magnetic resonance ventilation imaging of the lung in cystic fibrosis: comparison with high resolution CT and spirometry

The purpose of this study was to compare hyperpolarized ³helium magnetic resonance imaging (³He MRI) of the lungs in adults with cystic fibrosis (CF) with high-resolution computed tomography (HRCT) and spirometry. Eight patients with stable CF prospectively underwent ³He MRI, HRCT, and spirometry within 1 week. Three-dimensional (3D) gradient-echo sequence was used during an 18-s breath-hold following inhalation of hyperpolarized ³He. Each lung was divided into six zones; ³He MRI was scored as percentage ventilation per lung zone. HRCT was scored using a modified Bhalla scoring system. Univariate (Spearman rank) and multivariate correlations were performed between ³He MRI, HRCT, and spirometry. Results are expressed as mean±SD (range). Spirometry is expressed as percent predicted. There were four men and four women, mean age=31.9±9 (20–46). Mean forced expiratory volume in 1 s (FEV)₁=52%±29 (27–93). Mean ³He MRI score=74%±25 (55–100). Mean HRCT score=48.8±24 (13.5–83). The correlation between³He MRI and HRCT was strong (R=±0.89, p<0.001). Bronchiectasis was the only independent predictor of ³He MRI; ³He MRI correlated better with FEV₁ and forced vital capacity (FVC) (R=0.86 and 0.93, p<0.01, respectively) than HRCT (R=±0.72 and ±0.81, p<0.05, respectively). This study showed that ³He MRI correlates strongly with structural HRCT abnormalities and is a stronger correlate of spirometry than HRCT in CF.