Imaging early-stage corticobasal degeneration with [99mTc]TRODAT-1 SPET

The aim of this study was to investigate the nigrostriatal dopaminergic function in patients with corticobasal degeneration (CBD) using [2-[[2-[[[3-(4-chlorophenyl)-8-methyl-8-azabicyclo[3.2.1]oct-2-yl]methyl](2-mercaptoethyl)amino]ethyl]amino]ethanethiolato(3-)-N2,N2',S2,S2']oxo-[1R-(exo-exo)]-[99mTc]technetium ([99mTc]TRODAT-1) brain single-photon emission tomography (SPET).

Five patients with probable CBD, 10 age- and duration-matched patients with idiopathic Parkinson's disease (IPD) and 10 age-matched healthy volunteers completed the SPET study. The images were obtained 4 h after intravenous injection of 925 MBq of [99mTc]TRODAT-1. Using a magnetic resonance imaging atlas of the striatum, the ratios of specific striatal binding to non-specific occipital binding were calculated.

Clinical analysis showed that the CBD patients obtained significantly higher scores on the Unified Parkinson's Disease Rating Scale and a significantly worse score for activities of daily living. In the CBD and IPD groups, striatum-occipital/occipital, caudate nucleus-occipital/occipital and putamen-occipital/occipital ratios decreased significantly relative to those of healthy subjects. No statistical difference could be found between the CBD and IPD groups for these ratios, although relatively even, decreased uptakes in the caudate nucleus and putamen were found in the CBD group. On further analysis of the index of binding reduction, the differences between the caudate nucleus and putamen were significantly lower in the CBD group than in the IPD group. The striatal uptake of [99mTc]TRODAT-1 showed a distinct asymmetry in both the CBD and IPD patients.

From this study, it can be concluded that early-stage CBD patients have a worse performance and more difficulties with daily activities than IPD patients. CBD patients demonstrated essentially similar patterns of [99mTc]TRODAT-1 binding as those with IPD. However, there was relatively more homogeneous involvement of the caudate nucleus and putamen in the CBD patients. This provides information about the differences between these patients in the early stages.