Use of neuromelanin-sensitive MRI to distinguish schizophrenic and depressive patients and healthy individuals based on signal alterations in the substantia nigra and locus ceruleus

Background: We investigated alterations in the substantia nigra pars compacta (SNc) and locus ceruleus (LC) in schizophrenic and depressive patients by using a neuromelanin-sensitive magnetic resonance imaging (MRI) technique that enables direct visualization of these nuclei and examined whether this technique could distinguish between these disorders and healthy subjects. Methods: Using a neuromelanin-sensitive T1-weighted MRI technique, we examined 20 schizophrenia patients, 18 depressive patients, and 34 healthy control subjects. The signal intensities of the areas corresponding to the SNc and LC were measured, and the contrast ratios (CR) to the adjacent white matter were calculated. Results: The CR of the SNc was significantly higher in schizophrenic patients (22.6 +/- 5.6) than in depressive patients (19.2 +/- 4.7) and healthy control subjects (19.6 +/- 3.8), whereas the CR of the LC in depressive patients (7.7 +/- 2.4) was significantly lower than that in healthy control subjects (11.0 +/- 3.9) and schizophrenic patients (10.0 +/- 3.1). Further, the difference in the CR between the SNc and LC was significantly greater in schizophrenic patients (12.6 +/- 6.7) than in control subjects (8.6 +/- 4.1). Conclusions: Neuromelanin-sensitive MRI enables visualization of alterations in the SNc and LC that are observed in schizophrenia and depression.