Each participants first session contains 
- a 3D MP2RAGE T1w data set of the whole brain.
- a DTI dataset of a partial volume of the brain focused on the basal ganglia and basal forebrain.

DTI data in session 1 is read out with phase encoding direction anterior to posterior.

As far as provided, session 2 contains DTI data of the same brain volume with phase incoding direction posterior to anterior.

Sequence protocol for DTI data:
b = 1000 s/mm², TR = 3000 ms, TE = 67 ms, 25 axial slices, voxel size 1.4 x 1.4 x 1.4 mm³, 64 directions spanning the whole sphere, 2 averages, intermingled volumes with a b-value of 0 sec/mm².