Dual-phase β-Amyloid PET for Assessment of Neuronal Injury and Amyloidosis in Corticobasal Syndrome

Ziel/Aim In recent years several ¹⁸F-labelled amyloid PET (Aβ-PET) tracers have been developed and have obtained clinical approval. Aβ-PET perfusion imaging for assessment of neuronal injury has not yet been tested in neurodegenerative disorders with cortical and subcortical affection. Therefore, we investigated the performance of early acquisition¹⁸F-flutemetamolAβ-PET in comparison to ¹⁸F-fluorodesoxyglucose (FDG)-PET in corticobasal syndrome (CBS).

Methodik/Methods Subjects with clinically possible or probable CBS were recruited within the prospective Activity of Cerebral Networks, Amyloid and Microglia in Aging and Alzheimer’s Disease (ActiGliA) observation study and all CBS cases with an available FDG-PET prior to Aβ-PET were selected. Aβ-PET was acquired 0-10 min p.i. (early-phase) and 90-110 min p.i. (late-phase) whereas FDG-PET was recorded from 30-50 min p.i. Semiquantitative regional values and asymmetry indices were compared between early-phase Aβ-PET and FDG-PET. Visual assessments of hypoperfusion and hypometabolism were compared among both methods. Late-phase Aβ-PET was evaluated visually for assessment of amyloid-positivity.

Ergebnisse/Results Among 20 evaluated patients with CBS, 5 were Aβ-positive. Early-phase Aβ-PET and FDG-PET SUVr correlated highly in cortical (mean R=0.86, range 0.77-0.92) and subcortical brain regions (mean R=0.84, range 0.79-0.90). Strong asymmetry was observed in FDG-PET for the central region (|AI|=2.9%), the parietal cortex (|AI|=2.9%), and the thalamus (|AI|=5.5%), correlating well with AI of early-phase Aβ-PET (mean R=0.87, range 0.62-0.98). Visual assessments of hypoperfusion and hypometabolism were highly congruent. Hypometabolism was estimated to precede hypoperfusion at an average of 6.9 months.

Schlussfolgerungen/Conclusions Early-phaseAβ-PET facilitates assessment of neuronal injury in CBS for cortical and subcortical areas. Known asymmetries in CBS are also captured by this method, enabling assessment of Aβ-status and neuronal injury with a single radiation exposure at a single visit.