Fig. 1.

Procedure for the fully automated CC segmentation and texture analysis. (A) Alignment of T1w data: AC and PC were manually defined in 100 data sets of healthy controls so that a T1w template could be created by arithmetic averaging of all data sets. (B) T1w data of all study participants were fit to the T1w template. (C) The intensity threshold was varied from 100% to 0% of maximum intensity and the area size of the midsagittal CC plane was calculated. Beginning with an area size of 0 mm² at threshold 100%, the area size of the CC plane remains stable at 0 mm² during the initial decrease of the intensity threshold until a “step” occurs between about 80% and 60% of maximum intensity; the intensity threshold for CC segmentation was then defined as this “step”-threshold minus 3% (red arrow). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)