Figure 1  .

Coronal and transverse computed tomographic (CT) scans of dry vertebrae, 1 mm slice thickness, 120 kV, 250 mA. Left, a young adult vertebra, mean (SD) x ray absorption -570 (102) Houndsfield Units (HU). Right, an osteoporotic vertebra, x ray absorption -827 (103) HU. The right hand figures are representative middle third scans from a sample of 61 triplanar CT scans made across three osteoporotic vertebrae. The transverse scan B2 shows substantial loss of radial and annular trabeculae. There is some loss of axial trabeculae with thickening of several unsupported survivors. The pattern of bone loss is not uniform across the transverse section, and differs from that seen in coronal and sagittal sections.