Susceptibility-weighted images (SWI) are generated from gradient-echo (GRE) pulse sequences. Since GRE sequences lack the ability to refocus spins that experience phase loss due to magnetic field inhomogeneities, they exhibit high sensitivity to differences in tissue susceptibilities. Biological tissues generally exhibit weak diamagnetic properties; however, tissues containing iron, gadolinium, copper, or manganese demonstrate paramagnetic behavior, while iron complexes such as ferritin and hemo…