Impact of florbetaben PET imaging on diagnosis and management of patients with suspected Alzheimer’s Disease eligible for CSF analysis in France

Objectives: Alzheimer’s Disease (AD) is not easily diagnosed, particularly in early onset of dementia and for atypical or mixed presentations. The current study investigates the impact of florbetaben PET imaging on the diagnosis and management of patients where the aetiology of symptoms remained unexplained after a complete diagnostic work up.

Methods: This multicenter study was performed at tertiary memory clinics in France in patients who were eligible for analysis of CSF according to French Health Authority (HAS) recommendations, and for whom lumbar puncture (LP) was not feasible, refused or results considered as ambigous. Following an initial diagnosis (visit 1), florbetaben amyloid imaging was performed (visit 2), and a confirmed or revised diagnosis was provided after disclosure of PET results in a follow-up visit (visit 3). Visual florbetaben PET image assessment was performed locally in each centre by readers who had undergone training for appropriate interpretation of scans. Changes in diagnosis, diagnostic confidence and patient management after PET result disclosure were analyzed.

Results: The study cohort included 205 subjects (male n=103; 70.9±9.7 years). The full dataset for this analysis contained subjects with available and evaluable florbetaben scans (87 patients with LP, 118 without LP). A very high proportion of diagnoses were changed after PET result disclosure (137/205:66.8% [59.9-73.2 95% CI]), more frequently for negative scans (PET+: 76/132, 57.6%, PET-: 61/73, 83.6%, p<0.0001). Diagnostic confidence was significantly higher for final diagnoses (167/205: 81.5% with improved confidence, p<0.0001). Changes in management were reported for a significant proportion of patients (164/205: 80% [73.9-85.2 95% CI]), independently of PET status (PET+: 106/132, 80.3% [72.5-86.7 95% CI]; PET-: 58/73, 79.5% [69.4-88.0 95% CI], p>0.05).

Conclusion: Florbetaben imaging influenced clinical expertise and decisions in an unique patient population in whom LP was not feasible or CSF analysis was inconclusive. The results encourage the implementation of amyloid imaging in care for AD patients with unexplained symptom aetiology after a full clinical work up. Research Support: The study was sponsored by Piramal Imaging Ltd.