Differentiating between progressive supranuclear palsy and corticobasal degeneration by brain perfusion SPET

The purpose of this study was to evaluate the usefulness of brain perfusion single photon emission computed tomography (SPET) to differentiate between progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD). Twelve patients with PSP and 12 with CBD were examined by brain perfusion SPET using 99Tc(m)-ethyl cysteinate dimer (99Tc(m)-ECD). The regions of interest (ROIs) were five cortical regions, the basal ganglia, the thalamus, the cerebellar cortex and the brain stem. The mean regional cerebral blood flow (CBF) and the mean right/left asymmetry index in each ROI were calculated. The asymmetry index of the regional CBF was significantly higher in CBD patients compared with PSP patients in all of the cortical regions and in the basal ganglia. The greatest differences in asymmetry were in the parietal cortex (P<0.001), high frontal cortex (P<0.001), frontal cortex (P<0.005), temporal cortex (P<0.01) and basal ganglia (P<0.01). Significant asymmetry was also detected in the occipital cortex (P < 0.05). No significant difference in asymmetry was found in the thalamus or the cerebellum. There were no significant differences between the two groups in any of the regional CBF values. In conclusion, brain perfusion SPET with 99Tc(m)-ECD is useful in detecting the significantly higher perfusion asymmetry in CBD patients compared with PSP patients in all cortical regions and in the basal ganglia. SPET may be a useful tool for differentiating between PSP and CBD.