Amyloid PET Positivity in Different Primary Progressive Aphasia Phenotypes

Area of Science:

• Neurology
• Nuclear Medicine
• Neuroimaging

Background:

• Primary progressive aphasia (PPA) is a neurodegenerative syndrome characterized by progressive language impairment.
• Alzheimer disease (AD) pathology is frequently observed in logopenic PPA (LPA).
• Accurate diagnosis of PPA subtypes and underlying pathology is crucial for patient management.

Purpose of the Study:

• To characterize F-florbetapir positron emission tomography (PET) imaging in patients with PPA.
• To assess the value of clinical characterization in predicting PPA pathology using F-florbetapir PET.
• To quantify amyloid load in PPA patients and compare it with typical AD patients.

Main Methods:

• A retrospective PET study using F-florbetapir was conducted on 12 patients with PPA (3 semantic-variant, 5 nonfluent, 1 LPA, 3 unclassifiable).
• Amyloid deposition was evaluated and compared between PPA subtypes and 11 patients with typical amnestic AD.
• F-florbetapir uptake was quantified and its distribution analyzed.

Main Results:

• 66.7% of PPA patients (8/12) were amyloid-positive by F-florbetapir PET.
• Amyloid positivity varied across PPA subtypes: 1/3 semantic-variant, 4/5 nonfluent, 2/3 unclassifiable, and 1/1 LPA.
• PPA patients with amyloid positivity showed significantly higher F-florbetapir uptake than typical AD patients in most regions.

Conclusions:

• F-florbetapir PET imaging shows promise for routine clinical use in identifying AD pathology in PPA.
• The imaging technique can aid in differentiating PPA subtypes and their underlying pathologies.
• This approach may improve diagnostic accuracy for PPA patients.