• 18F-Florbetapir
• Malattia di Alzheimer
• Mild Cognitive Impairment
• PET/TC Cerebrale

BACKGROUND:
Pathologic deposition of amyloid β (Aβ) protein is a fundamental component in the pathogenesis of Alzheimer’s disease (AD). PET ligands for Aβ protein are increasingly used in diagnosis and research of dementia syndromes. Here, we report a preliminary experience about PET study using 18F-florbetapir in patients with AD and Mild Cognitive Impairment (MCI) .
METHODS:
Twenty cognitively impaired patients (mean age ± SD, 72 ± 7.5) were recruited for the study. At the enrolment and after a year of follow-up, all patients underwent detailed clinical and neuropsychologic assessment using Alzheimer’s Disease Assessment Scale-Subscale Cognitive (ADAS- Cog) and Mini Mental State Examination (MMSE). All participants underwent dynamic 18F-florbetapir PET on a high-resolution research tomography. Static PET images were dichotomically (positive or negative ) evaluated by four trained raters masked to clinical status. The “majority” interpretation was made. The concordance among the four different interpretations was performed using Fleiss’s Kappa. Also concordances between the “majority” interpretation (MI) and cognitive tests, and MI and final clinical diagnosis were performed applying Cohen’s Kappa. Finally paired t test and Wilcoxon signed rank test were applied to estimate the statistic difference between initial and final ADAS-Cog and initial and final MMSE.
RESULTS
A statistic difference between initial and final MMSE (95% CI: 1,16 – 6,24, t(19) = 3,05, p-value = 0,003274; Wilcoxon signed rank: p-value = 0,0004529) and initial and final ADAS-Cog (paired t test: 95% CI: 0,06 – 7,24, t(19) = 2,13, p-value = 0,02344; Wilcoxon signed rank: p-value = 0,03173) was found.
Among raters Fleiss’s Kappa value was 0.583, Cohen’s Kappa was good both between the MI and cognitive tests (MI/ADAS-Cog Cohen’s Kappa=0,737 and MI/MMSE Cohen’s Kappa=0,615) and with final clinical diagnosis (Cohen’s Kappa= 0,737)


CONCLUSIONS:
18F-florbetapir seems to be a safe and useful radiotracer to detect cerebral Aβ deposits, with a good concordance among trained raters and between PET’s results and clinical data.