Physiological Whole-Brain Distribution of [¹⁸F]FDOPA Uptake Index in Relation to Age and Gender: Results from a Voxel-Based Semi-quantitative Analysis.

6-[ <sup>18</sup> F]fluoro-L-DOPA ([ <sup>18</sup> F]FDOPA), a positron emission tomography (PET) amino-acid tracer of brain decarboxylase activity, is used to assess the brain dopaminergic system. Using a voxel-based semi-quantitative analysis, this study aimed to determine whether a current brain uptake index of [ <sup>18</sup> F]FDOPA, expressed relative to the occipital background level, varies according to age and gender. One hundred and seventy-seven subjects were retrospectively included. A whole-brain statistical parametric mapping analysis of the [ <sup>18</sup> F]FDOPA uptake index in parametric PET images was performed at a voxel threshold of p < 0.05 (corrected) and p < 0.005 (uncorrected, k cluster > 125). Striatal uptake indices were influenced by age, negatively for the caudate nucleus and positively for the putamen, as well as by gender, with a lower left putaminal uptake index in women. Extra-striatal uptake indices were influenced by age, negatively for the frontal cortex and brainstem and positively for the occipital cortex and cerebellum, as well as by gender (diffuse increase in women). The uptake index of [ <sup>18</sup> F]FDOPA exhibited significant physiological variations according to age and gender and should therefore be considered for PET interpretation