[Comparison of Frontal and Lateral Measurements of Bone Mineral Density of the Lumbar Spine with Dual-energy X-ray Absorptiometry (DXA) in Spinal Deformity: a Phantom Study].

The bone mineral density (BMD) measurement of the lumbar spine with dual-energy X-ray absorptiometry (DXA) has the advantage of being able to detect early changes in BMD, which is usually used for the evaluation of drug therapy. However, DXA is not considered suitable for spinal deformity because it is a two-dimensional measurement. The aims of this study were to compare frontal and lateral measurements with a phantom and to examine the possibility of the evaluation of lumbar spine BMD in spinal deformity. The values of frontal and lateral measurements were compared when the lumbar phantom was tilted by 10 degrees from 0 to 40 degrees, assuming kyphosis, and when it was tilted by 5 degrees from 0 to 10 degrees to the right and left, assuming scoliosis. We revealed that in the case of kyphosis, the frontal is more accurate, and in the case of scoliosis, the lateral is more accurate; small rotation of subjects on the plane parallel to the image receiving surface could be acceptable. In general, the two-directional BMD measurement is useful for the improvement of the accuracy and may have a potential to measure patients with spinal deformity, which was previously thought to be impossible.