Neuromelanin MRI is useful for monitoring motor complications in Parkinson’s and PARK2 disease

Abstract

Parkinson's disease (PD) is caused by the loss of dopaminergic neurons. Recently, specific T1-weighted magnetic resonance imaging (MRI) at 3 Tesla was reported to visualize neuromelanin (NM)-related contrast of dopaminergic neurons. Using NM-MRI, we analyzed whether disease severity and motor complications (MC) are associated with the degree of dopaminergic neuronal degeneration in the substantia nigra pars compacta (SNc) in patients with idiopathic PD (PD) and PARK2. We examined 27 individuals with PD, 11 with PARK2, and a control group of 18. A 3T MRI was used to obtain a modified NM-sensitive T1-weighted fast-spin echo sequence. The size of the SNc was determined as the number of pixels with signal intensity higher than background signal intensity +2 standard deviations. NM-MRI indicated that the T1 hyperintense area in the SNc in patients with PD and PARK2 was significantly smaller than that in control subjects. When compared with the PD group without MC, both PD with MC and PARK2 showed a markedly smaller size of NM-rich SNc area. Receiver operating characteristic curve analysis revealed a sensitivity of 86.96% and a specificity of 100% in discriminating between patients with and without MC (area under the curve = 0.98). Correlation analysis between the T1 hyperintense SNc area and L-dopa and L-dopa equivalent dose demonstrated a significant negative correlation. The association between a reducing SNc NM-rich area and MC with increasing dopaminergic medication dose suggests that NM-MRI findings might be a useful tool for monitoring the development of MC in PD and PARK2.

Neuromelanin‐sensitive magnetic resonance imaging features of the substantia nigra and locus coeruleus in de novo Parkinson's disease and its phenotypes

“…It was also found that the SNc width was significantly negatively associated with the UPDRS motor score of the clinically most affected side in PD patients, in agreement with the growing clinical evidence which suggested that NM‐MRI changes were associated with disease severity . However, several studies revealed contradictory results . This discrepancy might partly be related to differences in the measurement methods and the recruited samples.…”

Neuromelanin imaging and midbrain volumetry in progressive supranuclear palsy and Parkinson's disease

“…A 3‐Tesla MRI unit was used to obtain a modified neuromelanin‐sensitive T1‐weighed fast‐spin echo sequence with an additional spectral presaturation inversion recovery pulse. We used a slightly modified version of the method reported by Schwarz and colleagues to quantify the high‐signal regions in the SNpc . We defined the high‐signal‐intensity region thought to reflect neuromelanin in the SNpc as the number of pixels exhibiting signals higher than +1.5 standard deviations (SDs) of the background signal, then used the high‐signal‐intensity region obtained by averaging the right and left SNpc as the NM‐SNpc area.…”

“…However, few studies have examined correlations between nigral degeneration and midbrain atrophy in PSP because conventional magnetic resonance imaging (MRI) techniques cannot visualize the SNpc in vivo. Recently, specific fast spin‐echo T1‐weighted MRI was reported to successfully visualize neuromelanin‐related contrast of dopaminergic neurons in the SNpc . Therefore, neuromelanin‐sensitive MRI (NM‐MRI) can be used to identify the dopaminergic neuronal degeneration underlying Parkinson's disease (PD) and other parkinsonian syndromes.…”

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

“…Recently, it was reported that decreased NM‐SNc size on NM‐MRI correlates with the prevalence of MFs in idiopathic PD and PARK2 disease . In addition, Hong et al .…”

“…Specific fast spin‐echo T1‐weighted magnetic resonance imaging (MRI) at 3 Tesla (neuromelanin MRI; NM‐MRI) can detect neuromelanin in dopaminergic neurons in the SNc . Kuya et al .…”