diagnostic imaging technique based on the detection of metabolites in tissues (tissue). Magnetic resonance spectroscopy (MRS) is related to magnetic resonance imaging (MRI) in that it uses the same machinery; however, instead of measuring blood flow, MRS measures the concentration of specific chemicals, such as neurotransmitters (neurotransmitter). MRS holds great promise in the diagnosis of diseases of the brain and of other parts of the body, including cancers (cancer) of the cervix, pancreas, and prostate (prostate gland).