High-resolution semiconductor PET system revealed metabolic activity of red nucleus and its correlation with cortical regions.

1621 Objectives Recent studies suggested possible role of red nucleus (RN) in cognitive functions. However, small size of RNs has limited application of functional imaging to investigate their metabolic activities. This study aimed to investigate the glucose metabolism of human RN and its correlation to other brain regions using a newly developed high-resolution semiconductor PET system. Methods Twenty patients without neurological disorders underwent whole brain scanning after injection of 400 MBq F-18 FDG. Maximum standardized uptake value (SUVmax) was measured within ROI placed over RN. Individual brain FDG-PET images were spatially normalized to the standard brain atlas to generate a surface projection map using a 3-dimensional stereotactic surface projection (3D-SSP) technique. Pearson’s product-moment correlation analysis was used in a voxel-by-voxel manner to evaluate metabolic association of RN with cerebral and cerebellar cortices. Results In all cases, right and left RNs were successfully visualized as a pair of foci showing increased FDG uptake relative to the surrounding midbrain. Quantitatively, average SUVmax of RN was higher (7.6±1.9) than that of dentate nucleus, but was lower than those of the caudate nucleus, putamen, and thalamus. The voxel-wise analysis revealed that RNs were significantly correlated with association cortices as well as motor cortex; however, the correlation was stronger in ipsilateral than in contralateral side. In addition, the left RN showed a stronger correlation with the motor cortices and cerebellum than the right RN did, while the right RN had a stronger correlation with the association cortices than the left RN did. Conclusions RN was functionally associated not only with the rubrospinal tract for muscle control, but also with the association cortex and limbic areas to suggest its roles in higher brain functions. Our results also suggested the differential roles of right and left RN.