Coefficient of variation of MRI indices derived from conventional tractography (vertical axis) and tract-probability maps (horizontal axis) across repeated scans of the same individual. Data are from 32 scans of 14 healthy volunteers, and the number of scans ranges from 2 to 4. Tracts are coded by color: Red, optic radiation; green, corpus callosum; blue, optic tract; purple, corticospinal tract. MRI indices are coded by symbol type: fractional anisotropy (■); mean diffusivity (●); parallel diffusivity (▲); perpendicular diffusivity (▼); quantitative T2 (♦); magnetization transfer ratio (+).