Fig. 4. SNc NM and iron probabilistic maps.

a 2D axial slices of probabilistic maps of NM and iron obtained from healthy subjects and PD patients. b 3D renders of HC and PD for NM in SNc (left), iron in SNc (middle), and iron burden in SN (right). c Colorbar for normalized voxel NM/iron content. Average brainstem mask is shown in gray. The probabilistic map shows the voxels for which most subjects contain NM/iron (warm colors) and the voxels for which few subjects contain NM/iron (cold colors). To improve visual quality, all maps were spatially upsampled by a factor of four using bicubic interpolation.