Fig 2.

ROIs on the substantia nigra on QSM images. Multiplanar reconstruction coronal images were selected at the 3 planes, that is, the anterior (red line), middle (light orange line), and posterior (blue line) edges of the red nucleus on axial QSM images (A), to measure spatial susceptibility differences in the anterior, middle, and posterior parts of the SN. To avoid contamination by the subthalamic nuclei, we placed an ROI on the aSN (B), mSN (C), and pSN (D) below the caudal edge of the RN on coronal QSM images. The averaged value of the aSN, mSN, and pSN was defined as the value of the whole SN. Solid arrow indicates the SN; dotted arrow, the RN.