Figure 3. Histogram of T₂* distribution of thresholded binary stained images of iron and neuromelanin (NM) pigments, and reference region from the Perl stain image substantia nigra (SN).

Significantly reduced (P < 0.0001) mean T₂* values were observed for both iron (blue) pigments and NM (brown) with respect to the reference SN tissue region as shown in T₂* histogram for both the 40-year-old male (subject I) and 70-year-old female (subject II) subjects. A: NM, B: iron pigments, C: reference SN tissue region.