Figure 3.

Illustration of dMRI indices and the corresponding uncertainty of an axial slice of dMRI volume from a human brain. The first row shows the $\text{FA}$, $\mathrm{\mu }\text{FA}$ and the corresponding standard deviation (STD). The second row illustrates the $\mathrm{\mu }{\text{FA}}_{\mathrm{slow}}$ and $\mathrm{\mu }{\text{FA}}_{\mathrm{fast}}$ measures, where $\mathrm{\mu }{\text{FA}}_{\mathrm{slow}}$ has relative higher values than $\mathrm{\mu }{\text{FA}}_{\mathrm{fast}}$. The third row shows $\text{SK}$ and $\mathrm{\mu }\text{SK}$. $\text{SK}$ has negative values in the white-matter region highlighted by the red and yellow circle whereas the corresponding $\mathrm{\mu }\text{SK}$ are positive, indicating that the underlying microscopic diffusion tensors have prolate shapes that are related to crossing fibers or fiber dispersion. Parameter uncertainty is inflated in a band toward the posterior of the brain. This is likely due to poor fat saturation causing a mixture of fat and water signals at this location, as previously described by⁹.