Figure 4.

Plots compare model-predicted relaxivities with published in vivo calibrations for different patterns of iron distribution as indicated (where NN is nearest neighbor). Proton diffusion was unrestricted. (a) R2*-iron relationship is relatively insensitive to iron morphology, (b) R2-iron relationship changes from linear to curvilinear when inter-cellular iron anisotropy and nearest neighbor constraints are applied. This brings forth the importance of clustered nature of iron in vivo.