SNMMI: Emerging PET Insights on Neuroinflammation with Progressive Apraxia of Speech (PAOS) and Parkinson-Plus Syndrome

Neuroinflammation may play a significant role in positron emission tomography (PET) detection of progressive apraxia of speech (PAOS) and determining whether there is coexisting Parkinson-plus syndrome, according to new research presented at the Society for Nuclear Medicine and Molecular Imaging (SNMMI) conference.

For the prospective study, researchers reviewed data from (¹¹C)ER176 TSPO PET and (¹⁸F)flortaucipir tau PET scans obtained for 25 patients with PAOS (including 13 patients with Parkinson-plus syndrome) and 30 healthy control participants.

In a recent interview at the SNMMI conference, lead study author Ryota Satoh, Ph.D., said the study findings revealed significantly greater neuroinflammation for patients with PAOS in regions such as the premotor cortex, basal ganglia and the superior, middle and inferior frontal gyri in contrast to PET scans from healthy control participants.

While the uptake pattern on PET scans was limited to the left frontal gyri and bilateral premotor cortex in patients with PAOS and no Parkinson-plus syndrome, Dr. Satoh noted that those with PAOS and Parkinson-plus syndrome had broader uptake that extended to prefrontal, temporal and parietal cortices.

“These results suggest that tau-associated neuroinflammation could occur in early stages of the disease, but the degree of neuroinflammation increases and spreads once the patient develop Parkinson-plus syndrome,” noted Dr. Satoh, an assistant professor in the Department of Radiology at Mayo Clinic in Rochester, Minn.

(Editor’s note: For additional coverage of the SNMMI conference, click here.)

While acknowledging the need for larger cohort longitudinal studies, Dr. Satoh said the neuroinflammation may emerge as a key consideration in disease treatment in this patient population.

“Our results suggest that inflammation plays an important role in the disease mechanisms of PAOS, and it is related to underlying … tau. These results indicate an inflammation mechanism could be the target of the treatment of this disease,” added Dr. Satoh.

(Editor’s note: For related content, see “FDA Clears Emerging Brain PET System,” “Can Brain MRI-Based Connectome Mapping Predict the Progression of Parkinson’s Disease?” and “Researcher Presents First Non-Invasive Images or Alpha-Synuclein in the Brain.”)

For more insights from Dr. Satoh, watch the video below.

Reference

1. Satoh R, Utianski RL, Duffy JR, et al. Neuroinflammatory (11C)ER176 TSPO PET profile with colocalized tau uptake in progressive apraxia of speech. Presented at the Society for Nuclear Medicine and Molecular Imaging (SNMMI) conference, June 21-24, 2025, New Orleans. Available at: https://www.xcdsystem.com/snmmi/program/B95p18u/index.cfm?pgid=2402&sid=46745&mobileappid=4674500000 .