Background
123I-FP-CIT (DaTSCAN®) SPECT imaging is widely used to study neurodegenerative parkinsonism, with the evaluation of presynaptic dopamine transporter (DAT) in striatal regions. Beyond DAT, 123I-FP-CIT may be also considered for other monoaminergic systems, in particular serotonin transporter (SERT). Independent Component Analysis (ICA) implemented in Source-Based Morphometry (SBM), a multivariate approach, represents an alternative method to explore monoaminergic neurotransmission, studying the relationship among voxels, and grouping them into “metabolic” neural networks.
Methods
One-hundred forty-three subjects (84 with Parkinson’s disease (PD) and 59 control individuals (CG)) underwent DATSCAN® imaging. The 123I-FP-CIT binding was evaluated by the multivariate SBM approach, as well as by region-of-interest (ROI) (caudate/putamen) (BRASS software) and whole-brain voxelwise univariate (Statistical Parametric Mapping, SPM) approaches.
Results
As compared to univariate approaches (BRASS and SPM), which only demonstrated striatal 123I-FP-CIT binding reduction in the PD group, SBM identified six sources of non-artifactual origin, including basal ganglia and cortical regions as well as brainstem. Among them, three sources (basal ganglia and cortical regions) presented loading scores (as index of 123I-FP-CIT binding) significantly different between PD and CG. Notably, even though not significantly different between PD and CG, the remaining three non-artifactual sources were characterized by a predominant frontal, brainstem and occipito-temporal involvement.
Discussion
The concept of source blind separation by the application of ICA (as implemented in SBM) represents a feasible approach to be considered in 123I-FP-CIT (DaTSCAN®) SPECT imaging. Taking advantage of this multivariate analysis, specific patterns of variance can be identified (involving either striatal or extrastriatal regions) that could be useful in differentiating neurodegenerative parkinsonisms.