To characterize brain FDG-PET/MRI features in patients with corticobasal syndrome (CBS) and evaluate its utility in early diagnosis of corticobasal degeneration (CBD)  

CBS is a relentless neurodegenerative disorder characterized by cognitive impairment and progressive motor symptoms that can be caused by tauopathies including CBD. Early diagnosis of CBD is crucial for prognostication. However, due to the clinical heterogeneity of CBS, diagnosis can be difficult. Apart from autopsy, there are few measures to objectively diagnose CBD. FDG PET-MRI can obtain structural and metabolic data simultaneously from patients with movement disorders. We explored the advantages of FDG PET-MRI imaging for the early diagnosis of CBD.    

Our cohort consists of 16 subjects (12 female; 72.6 ± 7.8 years; disease duration 2.3 ± 1.8 years). Cortical sensory loss was the most common clinical finding. The most common FDG/PET findings were decreased uptake in the thalamus, putamen, red nucleus, frontal cortex, perirolandic region contralateral to symptoms, and in the cerebellum ipsilateral to symptoms. The most common MRI findings were bilateral parietal and unilateral perirolandic atrophy contralateral to symptoms. PET-MRI helped establish an early diagnosis of CBD in 5 cases and helped confirm 11 cases of suspected CBD.    

Our findings are concordant with the literature including asymmetric FDG hypometabolism and volume loss in the frontoparietal cortices with hypometabolism in subcortical structures ipsilateral to the affected cortices. PET-MRI was instrumental in supporting the clinical diagnosis of CBD, especially in early stage of disease. Future data will incorporate a standardized PET-MRI analysis specifically evaluating for CBD.