Hyperpolarized 3He magnetic resonance imaging: Preliminary evaluation of phenotyping potential in chronic obstructive pulmonary disease

Rationale and objectives: Emphysema and small airway obstruction are the pathological hallmarks of chronic obstructive pulmonary disease (COPD). The aim of this pilot study in a small group of chronic obstructive pulmonary disease (COPD) patients was to quantify hyperpolarized helium-3 (He-3) magnetic resonance imaging (MRI) functional and structural measurements and to explore the potential role for 3He MRI in detecting the lung structural and functional COPD phenotypes. Materials and methods: We evaluated 20 ex-smokers with stage I (n = 1), stage II (n = 9) and stage III COPD (n = 10). All subjects underwent same-day plethysmography, spirometry, H-1 MRI and hyperpolarized He-3 MRI at 3.0 T. He-3 ventilation defect percent (VDP) was generated from He-3 static ventilation images and H-1 thoracic images and the He-3 apparent diffusion coefficient (ADC) was derived from diffusion-weighted MRI. Results: Based on the relative contribution of normalized ADC and VDP, there was evidence of a predominant He-3 MRI measurement in seven patients (n = 3 mainly ventilation defects or VDP dominant (VD), n = 4 mainly increased ADC or ADC dominant (AD)). Analysis of variance (ANOVA) showed significantly lower ADC for subjects with predominantly elevated VDP (p = 0.02 compared to subjects with predominantly elevated ADC; p = 0.008 compared to mixed group) and significantly decreased VDP for subjects with predominantly elevated ADC (p = 0.003, compared to mixed group). Conclusion: In this small pilot study, a preliminary analysis shows the potential for He-3 MRI to categorize or phenotype COPD ex-smokers, providing good evidence of feasibility for larger prospective studies. (C) 2009 Elsevier Ireland Ltd. All rights reserved.