Fig. 5.
Effect of iron extraction on MRI contrast in postmortem brain tissue. Iron extraction strongly reduces intracortical magnetic susceptibility–based contrast as evidenced from R2*-weighted, R2*, and frequency shift images. The frequency images show subtle signs of contrast reversal with extraction, suggesting a small, opposing frequency shift caused by the remaining myelin. The circular area of susceptibility shift at right bottom of postextraction images is caused by an entrapped air bubble.