Clinical application of MAO‐B PET using 18F‐THK5351 in neurological disorders

Abstract

Monoamine oxidase B (MAO‐B) is an enzyme localized to the outer mitochondrial membrane and highly concentrated in astrocytes. Temporal changes in regional MAO‐B levels can be used as an index of astrocytic proliferation, known as activated astrocytes or astrogliosis. MAO‐B is a marker to evaluate the degree of astrogliosis. Therefore, MAO‐B positron emission tomography (PET) is a powerful imaging technique for visualizing and quantifying ongoing astrogliosis through the estimate of regional MAO‐B levels. Each neurodegenerative disorder generally has a characteristic distribution pattern of astrogliosis secondary to neuronal loss and pathological protein aggregation. Therefore, by imaging astrogliosis, MAO‐B PET can be used as a neurodegeneration marker for identifying degenerative lesions. Any inflammation in the brain usually accompanies astrogliosis starting from an acute phase to a chronic phase. Therefore, by imaging astrogliosis, MAO‐B PET can be used as a neuroinflammation marker for identifying inflammatory lesions. MAO‐B levels are high in gliomas originating from astrocytes but low in lymphoid tumors. Therefore, MAO‐B PET can be used as a brain tumor marker for identifying astrocytic gliomas by imaging MAO‐B levels and distinguishing between astrocytic and lymphoid tumors. This review summarizes the clinical application of MAO‐B PET using 18F‐THK5351 as markers for neurodegeneration, neuroinflammation, and brain tumors in neurological disorders. Because we assume that MAO‐B PET is clinically applied to an individual patient, we focus on visual inspection of MAO‐B images at the individual patient level. Geriatr Gerontol Int 2023; ••: ••–••.