Flortaucipir Positron Emission Tomography Imaging Differentiates Alzheimer Disease From Other Neurodegenerative Diseases
In a cross-sectional, multicenter international trial, (JAMA. 2018;320(11):1151-1162.) it was shown that neuroimaging with [18F]flortaucipir-positron emission tomography (PET) was able to sensitively (89.9%) and specifically (90.6%) differentiate patients with Alzheimer’s disease (AD) from patients with other neurodegenerative diseases.
The tracer [18F]flortaucipir binds to the paired helical filamentous tau protein, the presence of which is a core neuropathologic feature of AD. In this study of 126 patients with mild cognitive impairment (MCI), 83 of whom were positive for amyloid-β (Aβ), which is indicative of MCI due to AD, 179 patients with AD dementia, 254 patients with other neurodegenerative diseases, and 160 patients who had no cognitive deficits underwent [18F]flortaucipir-PET. standardized uptake value ratio (SUVR) in 5 predefined regions of interest (ROIs) were measured and cut points for tau positivity were determined.
Subjects average age was 68.8 years and 51.1% of the participants were women. The proportions of patients who were Aβ positive were 26.3%, 65.9%, 100%, and 23.8% among cognitively normal controls, patients with MCI, patients with AD dementia, and patients with non-AD neurodegenerative disorders, respectively.
Specificity and sensitivity was determined by comparing imaging findings with clinical diagnosis. Secondary analyses using area under the curve (AUC) of [18F]flortaucipir SUVR in comparison to 3 established MRI measures was performed. The AUCs for all [18F]flortaucipir ROIs were higher (AUC range, 0.92-0.95) compared than the 3 volumetric MRI measures (AUC range, 0.63-0.75; all ROIs P < .001 and lower in MCI due to AD (AUC range, 0.75-0.84).
Although more research is needed in larger populations, these data are a good indication that [18F]flortaucipir-PET is useful and accurate tool for diagnosis of AD