Hyperpolarised gas Magnetic resonance imaging (MRI) (Hyperpolorised 3He and 129Xe MRI) provides novel regional functional images of the lungs. Over the past 14 years researchers at Sheffield Teaching Hospitals NHS Foundation Trust and University of Sheffield have been developing and evaluating different MRI techniques to investigate different aspects of the lung function with both Hyperpolorised 3He and more recently 129Xe gas and have tested these new methods in volunteers with healthy and diseased lungs. This proposed study is to further test the sensitivity of MRI pulse sequences with inhaled 129Xe gas in volunteers. This protocol serves to evaluate the sensitivity of pulse sequences for 129Xe magnetic resonance imaging in the lungs and monitoring the transient changes in vital signs during and following the gas inhalation. This includes evaluation of pulse sequences to image xenon in the heart and brain as well as in the lungs of volunteers.