Fig. 2.

Simulation results for estimation accuracy: Scenario I: (a) estimated ${\sigma }_{\gamma }^2\left(v\right)$ by using voxel-wise approach; (b) true ${\sigma }_{\gamma }^2\left(v\right)$ image; and (c) estimated ${\sigma }_{\gamma }^2\left(v\right)$ by using FMEM. Scenario II: (d) estimated ${\sigma }_{\gamma }^2\left(v\right)$ by using voxel-wise approach; (e) true ${\sigma }_{\gamma }^2\left(v\right)$ image; (f) estimated ${\sigma }_{\gamma }^2\left(v\right)$ by using FMEM.