Fig. 1.

Bone density evaluation on spinal CT. CT images of the third lumbar and sacral vertebrae and ilium. The vertebral body was equally divided into three parts in the cranio-caudal direction (a), and the bone density was measured in the cancellous bone surrounded by an oval contour excluding the vertebral endplate and cortical bone (112.39 HU) (b). The bone density of the pedicle was measured on the bilateral sides excluding the cortical bone (right: 101.32 HU, left: 92.24 HU) (b) in the axial section at the center in the cranio-caudal direction of the pedicle in a parasagittal section on CT (c). In the ilium, the bone density was measured in an area similar to that in the S1 pedicle excluding the cortical bone in an axial section at the S1 vertebral level (right: 57.53 HU, left: 132.15 HU) (d). The bone density of the S1 pedicle was measured in the same section (right: 37.18 HU, left: 105.95 HU) (d)