Fig. 2.

The coronal (A) and axial planes (B). A sagittal plane passing through the center of the femoral head (C) was selected. The region of interest (ROI) was set within 40° anteriorly and 40° posteriorly of a perpendicular line through the center of the femoral head in the sagittal plane (C). The ROI was divided into radial sections with equal widths and defined as the anterior femoral head (Fa), center femoral head (Fc), posterior femoral head (Fp), anterior acetabulum (Aa), center acetabulum (Ac), and posterior acetabulum (Ap) (D).