CC Curve Generation and Template Curve Selection

To extract the boundary curve from each 2D mid-sagittal section of CC, we used a boundary following algorithm (49) to identify the boundary pixels, starting with the point at the lower-left corner of CC and then arranging the boundary pixels clockwise to form a curve representing the 2D mid-sagittal CC shape which was analyzed later.

In LDDMM-curve based statistical shape analysis, a template curve is mapped to all target curves (curves from all participants). As such, the first thing is to select a template curve. In this study, we selected the template CC curve to be the one whose area was closest to the mean area averaged across all CC curves. This template selection method had been widely adopted and validated in LDDMM-based statistical shape analyses in previous works (35, 50, 51).