- Brain magnetic resonance spectroscopy (MRS) scans will be done at each visit. MRS uses a strong magnetic field and radio waves to take pictures of chemicals in the brain with a scanner. The participant will lie on a table that can slide in and out of the cylinder. While in the scanner the participant will hear loud knocking noises. They will get earplugs or earmuffs to muffle the sound. Medicines might be used to keep the participant asleep during the MRS.