Journal of nuclear medicine : official publication, Society of Nuclear Medicine
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Monoamine oxidase (MAO) regulates neurotransmitter concentration in the brain and is also an important detoxifying enzyme in peripheral organs. It occurs in 2 subtypes, MAO A and MAO B. Their relative ratios in different organs are variable, depending on the particular organ and species, making it difficult to extrapolate measures from animals to humans. The purpose of this study was to investigate the feasibility of imaging MAO B in peripheral organs in humans with PET. ⋯ This study demonstrates that (a) the deuterium isotope effect is useful in assessing the binding specificity of labeled deprenyl to peripheral MAO B; (b) MAO B can be visualized and quantified in the heart, lungs, kidneys, and spleen but not in the liver; (c) with the exception of the liver, which cannot be measured, MAO B activity is highest in the kidneys and heart; and (d) quantitation in organs having high levels of MAO B is improved by the use of 11C-L-deprenyl-D2, similar to prior studies on the brain. This study indicates that 11C-L-deprenyl-D2 will be useful for measuring the effects of different variables, including tobacco smoke exposure on MAO B activity in peripheral organs in humans.