Longitudinal changes in ¹⁸F-THK5351 positron emission tomography in corticobasal syndrome

Background and purpose: Corticobasal syndrome (CBS) is pathologically characterized by tau deposits in neuronal and glial cells and by reactive astrogliosis. In several neurodegenerative disorders, ¹⁸F-THK5351 has been observed to bind to reactive astrocytes expressing monoamine oxidase B. In this study, the aim was to investigate the progression of disease-related pathology in the brains of patients with CBS using positron emission tomography with ¹⁸F-THK5351. Methods: Baseline and 1-year follow-up imaging were acquired using magnetic resonance imaging and positron emission tomography with ¹⁸F-THK5351 in 10 subjects: five patients with CBS and five age-matched normal controls (NCs). Results: The 1-year follow-up scan images revealed that ¹⁸F-THK5351 retention had significantly increased in the superior parietal gyrus of the patients with CBS compared with the NCs. The median increases in ¹⁸F-THK5351 accumulation in the patients with CBS were 6.53% in the superior parietal gyrus, 4.34% in the precentral gyrus and 4.33% in the postcentral gyrus. In contrast, there was no significant increase in the regional ¹⁸F-THK5351 retention in the NCs. Conclusions: Longitudinal increases in ¹⁸F-THK5351 binding can be detected over a short interval in the cortical sites of patients with CBS. A monoamine oxidase B binding radiotracer could be useful in monitoring the progression of astrogliosis in CBS.