Magnetic resonance imaging (MRI) and angiography (MRA) measures are promising approaches to detecting and characterizing the anticipated acute pulmonary toxicities of e-cigarettes. Hyperpolarized helium (3He)-enhanced MRI may be more sensitive than spirometry, a global lung function measure, for determination of airway toxicities. 3He-enhanced MRI has been used to demonstrate the extent of ventilation defects in healthy persons with normal spirometry; to measure ventilation changes in asthmatics pre- and post-challenge with bronchodilators and methacholine; and to predict pulmonary hospitalizations in persons with COPD. Meanwhile, until recently, non-invasive measures of pulmonary vascular toxicities were lacking. The investigators have developed an innovative measure of pulmonary microvascular blood flow on gadolinium (Gd)-enhanced MRA, which the investigators found to be markedly abnormal in early chronic obstructive pulmonary disease (COPD) and emphysema, and to be associated with increased endothelial microparticles, a marker of endothelial dysfunction. Nonetheless, neither of these sensitive, non-invasive, repeatable, and reproducible measures has ever been used to assess e-cigarette toxicities.