Combined helium-3/proton magnetic resonance imaging measurement of ventilated lung volumes in smokers compared to never-smokers

Purpose: To use a combination of helium-3 (3-He) magnetic resonance imaging (MRI) and proton single-shot fast spin echo (SSFSE) to compare ventilated lung volumes in groups of healthy smokers diagnosed with moderate chronic obstructive pulmonary disease (COPD), and never smokers. Materials and Methods: All study participants were assessed with spirometry prior to imaging. 3-He images were collected during an arrested breath hold, after inhaling a mixture of 200 mL of hyperpolarized 3-He/800 mL of N-2. Proton SSFSE images were acquired after inhaling 1 liter of room air. The ventilated volume for each study participant was calculated from 3-He images, and a ratio was calculated to give a percentage ventilated lung volume. Results: Never-smokers exhibited 90% mean ventilated volume. The mean ventilated lung volumes for healthy smokers and smokers diagnosed with COPD were 75.2% and 67.6%, respectively. No correlation with spirometry was demonstrated for either of the smoking groups. Conclusion: Combined 3-He/Proton SSFSE MRI of the lungs is a noninvasive method, using nonionizing radiation, which demonstrates ventilated airspaces and enables the calculation of ventilated lung volumes. This method appears to be sensitive to early obstructive changes in the lungs of smokers.