Fig. 9.

The AIP, scattering coefficient (${\text{μ}}_{\mathrm{s}}$), back-scattering (${\text{μ}}_b^{\text{'}}$) and relative back-scattering ratio (r’) maps of a horizontal human midbrain section rotated by 30° counter-clockwise. ROIs: 1, cerebral peduncles; 2, substantia nigra; 3, red nucleus; 4, oculomotor nucleus; 5, periaqueductal gray; 6, fasciculus. Coordinates: A, anterior; P, posterior; M, medial; L, lateral. Scale bar: 2.5 mm. Note that the scales for ${\text{I}}_0$ and g’ are arbitrary as the backscattering coefficient units are not calibrated.