Neuromelanin-sensitive magnetic resonance imaging is able to visualize changes associated with neuronal loss in the substantia nigra pars compacta (SNc) and locus coeruleus (LC) in patients with Parkinson's disease (PD). However, the diagnostic accuracy of this technique in the early stages of PD remains unknown. Therefore, changes in the SNc and LC observed using neuromelanin imaging were evaluated in patients with early PD. The signal intensities of the lateral, central, and medial parts of the SNc and that of the LC were measured, and the contrast ratios (CRs) were calculated against the adjacent white matter structures. CRs in the lateral part of the SNc and in the LC were significantly reduced in the early PD group when compared with the controls. Sensitivities and specificities in discriminating early PD patients from healthy controls were 73% and 87% in lateral SNc and 82% and 90% in LC, respectively. Neuromelanin imaging can depict signal alterations in the lateral part of the SNc and in the LC in patients with PD, even in its early stage, and can discriminate between these patients and healthy individuals with high sensitivities and specificities.
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