Fig. 4.

Segmentation thresholds of T2*w hypointensities and median T2*w intensities of corresponding normal-appearing basal ganglia tissue. This figure shows that the rater chose different segmentation thresholds for T2*w hypointensities from different anatomical structures. This systematic variation suggests that the manual segmentation of T2*w hypointensities was potentially influenced by a difference in appearance of T2*w hypointensities from different basal ganglia structures. An additional influence might be the difference in appearance of the normal-appearing tissue intensities of the caudate, putamen, globus pallidus and internal capsule which look increasingly dark on T2*w volumes.