Clinical impact of [18F]flutemetamol PET among memory clinic patients with an unclear diagnosis

PurposeTo investigate the impact of amyloid PET with [F-18]flutemetamol on diagnosis and treatment management in a cohort of patients attending a tertiary memory clinic in whom, despite extensive cognitive assessment including neuropsychological testing, structural imaging, CSF biomarker analysis and in some cases [F-18]FDG PET, the diagnosis remained unclear.MethodsThe study population consisted of 207 patients with a clinical diagnosis prior to [F-18]flutemetamol PET including mild cognitive impairment (MCI; n=131), Alzheimer's disease (AD; n=41), non-AD (n=10), dementia not otherwise specified (dementia NOS; n=20) and subjective cognitive decline (SCD; n=5).ResultsAmyloid positivity was found in 53% of MCI, 68% of AD, 20% of non-AD, 20% of dementia NOS, and 60% of SCD patients. [F-18]Flutemetamol PET led, overall, to a change in diagnosis in 92 of the 207 patients (44%). A high percentage of patients with a change in diagnosis was observed in the MCI group (n=67, 51%) and in the dementia NOS group (n=11; 55%), followed by the non-AD and AD (30% and 20%, respectively). A significant increase in cholinesterase inhibitor treatment was observed after [F-18]flutemetamol PET (+218%, 34 patients before and 108 patients after).ConclusionThe present study lends support to the clinical value of amyloid PET in patients with an uncertain diagnosis in the tertiary memory clinic setting.