Neuromelanin or DaT-SPECT: which is the better marker for discriminating advanced Parkinson's disease?

BACKGROUND: To investigate whether the neuromelanin-positive substantia nigra pars compacta area (NM-SNc) on neuromelanin magnetic resonance imaging (NM-MRI), and the specific binding ratio (SBR) on 123 I-N-v-fluoropropyl-2b-carbomethoxy3b-(4-iodophenyl)nortropane single photon emission computed tomography (DaT-SPECT) can be correlated with motor fluctuations (MF) in advanced Parkinson's disease (PD).

METHODS: We enrolled 35 PD patients (60 ± 13 years) and 23 healthy individuals as controls (59 ± 19 years). The relationships between NM-MRI and DaT-SPECT were prospectively examined in two subgroups divided according to the presence or absence of MF. Multivariate analysis was performed using the Cox proportional hazard model to screen for association factors.

RESULTS: The NM-SNc size was correlated with SBR (Spearman's ρ = 0.43, p < 0.05). NM-SNc size was significantly reduced in PD with MF compared with those without (p < 0.001), whereas the SBR did not significantly differ between the groups. NM-SNc size was a significant association factor for MF (hazard ratio 0.94; p = 0.04). In receiver operating characteristic (ROC) analysis of the factors for MF occurrence, the area under the ROC curve of the NM-SNc size showed a significant difference of 0.89 (p < 0.05) but no significant difference was found in the SBR.

CONCLUSIONS: NM-SNc size was significantly correlated with the SBR in PD, but several factors in advanced PD were more closely associated with NM-SNc size than the SBR. NM-MRI might reflect the status of advanced PD more accurately than DaT-SPECT. Therefore, NM-MRI appears to provide a better marker for discriminating advanced PD than DaT-SPECT. This article is protected by copyright. All rights reserved.