Purpose:To evaluate the safety and tolerability of inhaling multiple 1-L volumes of undiluted hyperpolarized xenon 129 ( 129 Xe) followed by up to a 16-second breath hold and magnetic resonance (MR) imaging.
Materials and Methods:This study was approved by the institutional review board and was HIPAA compliant. Written informed consent was obtained. Forty-four subjects (19 men, 25 women; mean age, 46.1 years 6 18.8 [standard deviation ]) were enrolled, consisting of 24 healthy volunteers, 10 patients with chronic obstructive pulmonary disease (COPD), and 10 age-matched control subjects. All subjects received three or four 1-L volumes of undiluted hyperpolarized 129 Xe, followed by breath-hold MR imaging. Oxygen saturation, heart rate and rhythm, and blood pressure were continuously monitored. These parameters, along with respiratory rate and subjective symptoms, were assessed after each dose. Subjects' serum biochemistry and hematology were recorded at screening and at 24-hour follow-up. A 12-lead electrocardiogram (ECG) was obtained at these times and also within 2 hours prior to and 1 hour after 129 Xe MR imaging. Xenon-related symptoms were evaluated for relationship to subject group by using a x 2 test and to subject age by using logistic regression. Changes in vital signs were tested for signifi cance across subject group and time by using a repeated-measures multivariate analysis of variance test.