Hyperpolarized Xenon-129 Magnetic Resonance Imaging and Spectroscopy of Brown Fat: Healthy Adult Volunteer Pilot Study

In the fight against obesity, brown adipose tissue (BAT) is considered to be the newest target. The hypothesis is that this tissue is partially responsible for the imbalance between energy intake and energy expenditure that keeps lean people lean and obese people obese. As the detection of this tissue in adult humans is difficult, this study aim to evaluate the use of hyperpolarized xenon gas MRI for the detection of this tissue. Hyperpolarized xenon gas MRI is currently used for lung ventilation studies. For this study subjects will undergo an MRI scan for which they will also inhaled hyperpolarized xenon. Scans will be done before and during stimulation of thermogenic activity by cold exposure, while MR images and spectra will be acquired from the supraclavicular area. We expect that the inhaled gas will diffuse into blood and eventually reach BAT in a manner proportional to the metabolic activity of this tissue. Objectives of this studies are: * To detect BAT volume using hyperpolarized xenon MRI * To detect BAT thermogenic activity by hyperpolarized xenon Nuclear Magnetic Resonance (NMR) spectroscopy