Synaptic PET Imaging Differentiates Phase-Specific Neural Changes in Tinnitus

In a case-control cohort of 28 patients with acute or chronic tinnitus and 24 healthy controls, the ¹⁸F-SynVestT-1 tracer detected broader and more specific synaptic alterations than conventional ¹⁸F-FDG metabolic imaging, with regional SV2A changes that varied by disease phase.

Conventional evaluation relies on metabolic PET or MRI, whereas synaptic tracers quantify presynaptic vesicle-associated protein density rather than metabolic flux. The study used SUVR comparisons and brain-network analysis as primary endpoints, supporting more sensitive detection of presynaptic changes than metabolic measures.

¹⁸F-SynVesT-1 identified a broader pattern of abnormality than ¹⁸F-FDG (P<0.05), with clear regional contrasts: chronic-phase increases versus acute-phase decreases in synaptic signal.

Quantitatively, the study reported increased SV2A uptake in 14 brain regions among chronic patients, acute-phase reductions in five regions, and a focal decrease in the left inferior frontal gyrus; tracer uptake correlated with symptom severity. These region-specific differences suggest circuit-targeted synaptic remodeling and highlight limbic and fronto-insular networks as candidate therapeutic targets.