Use of amyloid PET/CT with 18 F-Florbetaben in the management of patients with Alzheimer's disease

Introduction and aim: Amyloid PET/CT is an "in vivo" imaging that may radically change management of Alzheimer's disease (AD) thanks to its ability to identify AD at the earliest stage. A diagnosis of dementia is currently made in terms of probability and is based on clinical evaluation (neuropsycological tests) as well as on the results of morphological imaging investigations (MRI) that can be supported by biohumoral (CSF analysis), and functional imaging only in the case of uncertain diagnosis of disease. The present study aimed to evaluate the role of amyloid PET/CT in the management of patients with suspicion of AD, through comparison with instrumental and clinical evaluation. Methods: 38 consecutive patients with suspicion of AD (23 female, 15 male; median age 63 years old, range 46-72), who performed 18F-florbetaben PET/CT, were retrospectively reviewed. All of them performed a previous instrumental evaluation. A subgroup of patients (24/38) were evaluated with Mini Mental State Examination (MMSE). Cohen's K test was used as a measure of agreement between previous instrumental examinations/clinical evaluation and beta-amyloid PET results. Results: Twenty-five/38 (65.8%) amyloid PET/CT scans resulted positive for amyloid deposition. Among the four target regions, precuneus was the most frequently involved. Previous instrumental evaluation was: MRI in 26/38 patients (24/26 positive for atrophy), CT in 9/38 (8/9 positive for atrophy), perfusion SPECT in 12/38 (8/12 areas of hypo-perfusion), 18F-FDG PET/CT in 2/38 (1/2 hypometabolism in frontal cortex). The agreement between previous instrumental examinations and beta-amyloid PET results was low (K= 0.084). In the subgroup of 24/38 patients, MMSE was scored positive (MMSE<24) in 14/24 (58.4%) and negative (MMSE>24) in 10/24 (41.6%). The agreement between clinical evaluation (MMSE) and beta-amyloid PET results was fair (K= 0.217). Conclusion: The low agreement between amyloid PET/CT and previous clinical and instrumental assessments that we found in our study suggests that the amyloid PET/CT provides additional and early information. To perform an early and differential diagnosis of AD could have a great impact on the patient's management and cost of care in order to perform the correct therapeutic interventions and to allow family members to manage adequately the patient's demanding care.