Abstract
The incidence of dementia in elderly population, aged 60 year or older, has been rapidly increasing. Dementia causes significant negative impacts on quality of lives, both in patients and families, constituting a huge socioeconomic burden and drawback in country’s development. Current diagnostic approach based on clinical symptoms and signs may not sufficient. Thus, early detection of amyloid deposition in the brain may play important role in accurate diagnosis, identifying patients at risk, planning for patient management and also leading to development the drug or procedure aimed for therapy or prevention of dementia. Objectives To evaluate the use of [F-18]Florbrtapir PET scan in assessing brain amyloid deposition in Alzheimer’s disease (AD), mild cognitive impairment (MCI) and healthy cognitive elderly (HC) and the correlation between brain amyloid deposition in PET scan and results from neuropsychological test, MRI brain and [F-18]FDG PET scan. We also aimed to evaluate the correlation between [F-18]Florbetapir PET scan results and changes in neuropsychological test, MRI brain and [F-18]FDG PET scan results. Methods 1) Synthesis of [F-18]Florbetapir PET tracer 2) Clinical study in 86 eligible subjects including 21 HCs, 33 MCIs and 32 ADs according to clinical diagnosis. All subjects underwent clinical and neuropsychological assessment including TMSE, CDR-SB, ADAS-COG, brain MRI, [F-18]FDG PET and [F-18]Florbetapir PET scan of the brain within 6-week period. The images were then analyzed using visual and quantitative analyses. Results The in-house synthesized [F-18]Florbetapir PET tracer demonstrated equivalent characteristics to those of reported original compound and passed the standard for drug for injection. There was no report of any adverse symptom after the study. The baseline clinical study in 86 eligible subjects found that results from all imaging techniques were concordant with clinical diagnosis and showed statistically significant correlation with neuropsychological test scores, either by visual assessment or quantitative analyses. The ability to differentiate AD from HC by [F-18] FDG PET was higher than [F-18]Florbetapir PET and MRI, respectively. Results from [F-18]Florbetapir PET were also significantly correlated with both [F-18]FDG PET and MRI, with higher correlation with [F-18]FDG PET>MRI. The results at 2-year follow-up period in 72 subjects (19 HCs, 31 MCIs and 22 ADs) found that baseline [F-18]Florbetapir PET results significantly and moderately correlated with the change in all neuropsychological test scores. But there was insignificant and low correlation between the change in quantitative results of [F-18]Florbetapir PET and the change in neuropsychological test scores. Moreover, the level of Aβ deposition in baseline [F-18]Florbetapir PET had high and significant correlation with the follow-up [F-18]Florbetapir PET in all brain regions and in AD>MCI>HC. Baseline [F-18]Florbetapir PET results also showed significant negative correlation with [F-18]FDG PET at parietal and occipital lobes in AD, although the level of correlation was relatively low. There was very low and insignificant correlation between baseline Aβ deposition and degree of mesial temporal atrophy at floow up. Conclusion The results from all imaging techniques showed concordance with clinical diagnosis and highly correlated with neuropsychological test results, which the highest correlation was detected in [F-18]FDG PET followed by [F-18]Florbetapir PET and MRI, respectively. Results from baseline [F-18]Florbetapir PET was well correlated with [F-18]FDG and MRI, both during baseline and follow-up, and also correlated with the change in neuropsychological test scores. The level of correlation varied among clinical groups and neuroimaging techniques.
