ABSTRACT
BACKGROUND AND PURPOSE: This study determined the correlation between uptake of the amyloid positron emission tomography (PET) imaging agent [(18) F]flutemetamol and amyloid-ß measured by immunohistochemical and histochemical staining in a frontal cortical biopsy. METHODS: Fifteen patients with possible normal pressure hydrocephalus (NPH) and previous brain biopsy obtained during intracranial pressure monitoring underwent [18F]flutemetamol PET. Seven of these patients also underwent [11C] Pittsburgh compound B (PiB) PET. [18F]Flutemetamol and [11C]PiB uptake was quantified using standardized uptake value ratio (SUVR) with the cerebellar cortex as a reference region. Tissue amyloid-ß was evaluated using the monoclonal antibody 4G8, Thioflavin-S and Bielschowsky silver stain. RESULTS: [18F]Flutemetamol and [11C]PiB SUVRs correlated with biopsy specimen amyloid-ß levels contralateral (râ =â 0.86, Pâ <â 0.0001; râ =â 0.96, Pâ =â 0.0008) and ipsilateral (râ =â 0.82, Pâ =â 0.0002; râ =â 0.87, Pâ =â 0.01) to the biopsy site. Association between cortical composite [(18) F]flutemetamol SUVRs and [11C]PiB SUVRs was highly significant (râ =â 0.97, Pâ =â 0.0003). CONCLUSIONS: [18F]Flutemetamol detects brain amyloid-ß in vivo with moderate to high sensitivity and high specificity. This agent, therefore, represents a valuable new tool to study and verify the presence of amyloid-ß pathology, both in patients with possible NPH and among the wider population.