Original MR image
+ Region Of Interest (ROI)

5x ROI
before enhancement
with edges marked

5x ROI
after enhancement
with edges marked

5x ROI
after enhancement
with rulers for direct measurements

d1 = 8.15 ± .01mm
d2 = 8.12 ± .01mm

5x ROI
after enhancement
with outline for indirect measurement

d = 2*sqrt(area/π) = 8.24mm