Fig. 4.

The images on the top are derived from equation 3. The image on the left is from a 22 yr female subject, and the image on the right is from a 75 yr female subject. The plot on the bottom are of the results from all 120 subjects for the images derived from equation 3. Shaded circles indicate the mean intensity for each age group, and the error bars show the range. A linear best fit, indicated by the dotted line, follows y=0.2968x+14.298, and has an R-squared value of 0.3861.