hyperpolarized xenon-129 magnetic resonance imaging and spectroscopy of brown fat: healthy adult volunteer pilot study

Conditions: Obesity

Summary: the primary goal of this study is to evaluate the feasibility of detecting brown adipose tissue (bat) in healthy subjects by using hyperpolarized xenon gas mri. in this pilot study, mri of bat of healthy adult volunteers will be performed at 3 tesla to assess image quality using a prototype surface coil and pulse sequence following inhalation of hyperpolarized 129xe (xenon) gas at thermoneutrality and under mild cold condition. the investigators are testing the abilities of xenon mri to see brown adipose tissue and detect its thermogenic activity.

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

Eligibility criteria:
inclusion criteria: * ability to give informed consent * willing to participate in this study * male or female ≥ 18 years of age at the time of the interview. * subject has no diagnosed pulmonary condition * subject has not smoked in the previous 5 years * smoking history, if any, is less than or equal to 5 pack-years * written informed consent (and assent when applicable) obtained from subject or subject's * legal representative and ability for subject to comply with the requirements of the study * healthy subject that may or may not have undergone an fluorodeoxyglucose -pet scan exclusion criteria: * any contraindication to mri (presence of any non-removable metal implant, stents, pacemaker, clips, staples, or piercings, etc. ) * subject does not fit in the magnet * pregnancy or breast feeding * severe claustrophobia * subject is less than 18 years old * mri is contraindicated based on responses to mri screening questionnaire * subject is pregnant or lactating * respiratory illness of a bacterial or viral etiology within 15 days of mri * subject has received an investigational medicinal product (not including 129xe) within 30 days of mri * subject has any form of known cardiovascular disease * subject cannot hold their breath for 15 seconds * subject deemed unlikely to be able to comply with instructions during imaging * subject is taking beta blockers * subject underwent an fluorodeoxyglucose-pet examination less than one week before the hp xenon mri scan

Keywords: brown adipose tissue hyperpolarized xenon gas mri