PET Scans Distinguish Alzheimer Disease From Other Neurodegenerative Diseases

alzheimer's progression PET
alzheimer’s progression PET
The use of positron emission tomography was able to discriminate between Alzheimer disease and other neurodegenerative disorders in a multicenter, cross-sectional study conducted at 3 dementia centers in South Korea, Sweden, and the United States.

The results of a study published in JAMA showed that [18F]flortaucipir positron emission tomography (PET) was able to differentiate Alzheimer disease (AD) from other neurodegenerative disorders. The multicenter, cross-sectional study was conducted at 3 dementia centers: 1 each in South Korea, Sweden, and the United States.

The investigators sought to examine the discriminative accuracy of [18F]flortaucipir PET for the diagnosis of AD vs non-AD neurodegenerative diseases. A total of 719 participants were recruited for the study between June 2014 and November 2017 and were grouped as follows: cognitively normal control participants (n=160); patients with mild cognitive impairment (MCI), of whom 65.9% tested positive for amyloid β (ie, MCI because of AD) (n=126); patients with AD dementia (n=179); and patients with a variety of non-AD neurodegenerative disorders (n=254).

The reference standard used in this study was the clinical diagnosis established at the 3 specialized memory centers. The primary analysis examined the discriminative accuracy — that is, the sensitivity and specificity — of [18F]flortaucipir for AD dementia vs all non-AD neurodegenerative diseases. The secondary analysis compared the area under the curve (AUC) of [18F]flortaucipir standardized uptake value ratio (SUVR) with 3 established magnetic resonance imaging measures (ie, hippocampal volumes, AD signature, and whole-brain cortical thickness). In addition, the sensitivity and specificity of [18F]flortaucipir in MCI because of AD vs non-AD neurodegenerative disorders were established.

The mean age of the participants was 68.8±9.2 years; 48.4% of the patients were men. The proportions of individuals who were amyloid β-positive were as follows: 26.3% among cognitively normal individuals , 65.9% among patients with MCI , 100% among patients with AD dementia , and 23.8% among patients with non-AD neurodegenerative disorders.

[18F]flortaucipir uptake in the medial-basal and lateral temporal cortex revealed 89.9% (95% CI, 84.6%-93.9%) sensitivity and 90.6% (95% CI, 86.3%-93.9%) specificity using the threshold according to control participants (SUVR, 1.34) for distinguishing AD from all non-AD neurodegenerative disorders. In contrast, the values were 96.8% (95% CI, 92.0%-99.1%) sensitivity and 87.9% (95% CI, 81.9%-92.4%) specificity using the Youden index-derived cutoff (SUVR, 1.27) for discriminating AD dementia from all non-AD neurodegenerative diseases.

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The AUCs for the 5 [18F]flortaucipir predefined regions of interest (ROIs) were significantly higher (AUC range, 0.92-0.95) than for the 3 volumetric magnetic resonance imaging measures (AUC range, 0.63-0.75; P <.001 for all ROIs). The diagnostic performance of the 5 [18F]flortaucipir ROIs was lower in patients with MCI because of AD (AUC range, 0.75-0.84).

The investigators concluded that the accuracy and potential use of [18F]flortaucipir PET in patient care warrant additional research in populations of patients that are more clinically representative.


Ossenkoppele R, Rabinovici GD, Smith R, et al. Discriminative accuracy of [18F]flortaucipir positron emission tomography for Alzheimer disease vs other neurodegenerative disorders. JAMA. 2018;320(11):1151-1162.