Regional locus coeruleus degeneration is uncoupled from noradrenergic terminal loss in Parkinson ’s disease

We examined 93 subjects (40 healthy controls and 53 Parkinson’s disease patients) with neuromelanin-sensitive turbo spin-echo MRI and calculated locus coeruleus-to-pons signal contrasts. Voxels with the highest intensities were extracted from published locus coerule us coordinates transformed to individual MRI. To also investigate a potential spatial pattern of locus coeruleus degeneration, we extracted the highest signal intensities from the rostral, middle, and caudal third of the locus coeruleus. Additionally, a study-specific probabilistic map of the locus coeruleus was created and used to extract mean MRI contrast from the entire locus coeruleus and each rostro-caudal subdivision. Locus coeruleus volumes were measured using manual segmentations.A subset of 73 subjects had11C-MeNER PET to determine noradrenaline transporter density, and distribution volume ratios of noradrenaline transporter-rich regions were computed. Patients with Parkinson ’s disease showed reduced locus coeruleus MRI contrast independently of the selected method (voxel approaches:P  < 0.0001,P  < 0.001; probabilistic map:P  < 0.05), specifically on the clinically-defined most affected side (P  < 0.05), and reduced locus coeruleus volume (P  < 0.0001). Reduced MRI contrast was confined to the middle and caudal locus coeruleus (voxel approach, rostral:P  = 0.48, middle:P  < 0.0001, and caudal:P  < 0.05; probabilistic map, rostral:P  = 0.90, mi...
Source: Brain - Category: Neurology Source Type: research