Hyperpolarized 3He Ventilation Defects and Apparent Diffusion Coefficients in Chronic Obstructive Pulmonary Disease

Abstract

Hyperpolarized 3He magnetic resonance imaging (3He MRI) at 3.0 Tesla of healthy volunteers and chronic obstructive pulmonary disease (COPD) patients was performed for quantitative evaluation of ventilation defects and apparent diffusion coefficients (ADC) and for comparison to published results acquired at 1.5 Tesla. The reproducibility of 3He ADC and ventilation defects was also assessed in subjects scanned 3 times, twice within 10 minutes, and again within 7 +/- 2 days of the first MRI visit. Hyperpolarized 3He MRI was performed in 6 subjects. Two interleaved images with and without additional diffusion sensitization were acquired with the first image serving as a ventilation image from which defect score and volume were measured and the combination of the 2 images used to compute ADC maps and ADC histograms. He MRI at 3.0 Tesla showed increased mean ADC and ADC standard deviation for subjects with COPD compared with healthy volunteers (ADC healthy volunteer (0.24 +/- 0.12 cm2/s), mild-moderate COPD (0.34 +/- 0.14 cm2/s), and severe COPD (0.47 +/- 0.21 cm2/s), and these values were similar to previously reported results acquired at 1.5 Tesla. Reproducibility of mean ADC was high (coefficient of variation 2% in severe COPD, 3% in mild-moderate COPD, 4% in healthy volunteers) across all 3 scans. Higher same-day scan reproducibility was observed for ventilation defect volume compared with 1-week scan reproducibility in this small group of subjects. ADC values for emphysematous lungs were significantly increased compared with healthy lungs in age-matched subjects, and all values were comparable to those reported previously at 1.5 Tesla. Ventilation defect score and ventilation defect volume results were also comparable to results previously reported in COPD subjects Reproducibility of ADC for same-day scan-rescan and 7-day rescan was high and similar to previously reported results.