FIGURE 2.

Imaging results from the normal brain. Magnified regions highlight different gray matter structures: the cerebral cortex (a), the putamen (b), the head of the caudate nucleus (c), and the thalamus (d). The T₁-weighted image was darker in gray matter than in white matter, with lowest intensities in the cerebral cortex and in the head of the caudate nucleus followed by the putamen. The T₂-fluid-attenuated inversion recovery (FLAIR) image featured a similar but opposite pattern. The image obtained as the ratio between the T₁-weighted and the T₂-FLAIR images featured a sharp contrast that emphasized myelin-rich regions such as the corpus callosum and the internal capsule (arrows). Both the fractional anisotropy (FA) map and the microscopic diffusion anisotropy (MK_A) map were dark in gray matter and bright in white matter. However, the FA was comparatively low in the anterior corona radiata (arrow), and the MK_A revealed higher levels of microscopic anisotropy in the lateral thalamus and in the medial putamen (arrows). All contrasts were coregistered to the T₁-weighted image space. The T₁-weighted and T₂-FLAIR intensities are in arbitrary units, and the FA and MK_A are dimensionless