Fig. 1.

Computation of T₁ z-score maps and periventricular gradient extraction. Representative slices of (A) the anatomical study-specific template, (B) the normative T₁ atlas, and (C) the distance to ventricles of the supratentorial WM voxels. The intercept, sex, age, and age² maps in (B) are intended as the β₀, β_sex, β_age and β_age2 coefficients of the following equation describing the expected reference T₁ value in a given brain voxel: $E\left\{T1\right\}={\beta }_{0,T1}+{\beta }_{\mathit{sex},T1}\ast sex+{\beta }_{\mathit{age},T1}\ast age+{\beta }_{age2,T1}\ast {\mathit{age}}^2$, with sex being a categorical variable and the age expressed in years and centred at the mean age of the healthy control cohort (37 y). The first band was excluded to minimise the partial volume effect.