| Bone mineral density detected by dual-energy X-ray absorptiometry isrecommended by World Health Organization and International Society forClinical Density, as the “gold standard” for the evaluation of osteoporosis. Thisdiagnostic method of osteoporosis is now widely used, and the diagnosticequipment is quite popular. In clinical practice, detection of spine and hip bonemineral density is mainly performed, and testing sites include the lumbar spine（L1~L4）, total hip, and femoral neck specifically.Although the Consensus ofISCD sets out the choices of bone mineral density measurement sites andregions of interest, lumbar vertebral BMD in the anteroposterior view isrecommended to all adults beyond50years by quite a few researchers.However, the elderly who has a higher prevalence of osteoporosis oftensuffers from degenerative scoliosis. And, it was reported that the overallincidence of adult scoliosis is about2~32%, but in the elderly population whooften accompanied by osteoporosis, the incidence of scoliosis goes up to60%. Scoliosis appears abnormal coronal vertebral sequence, and associated withvertebral rotation deformity, which might lead to reduced accuracy in BMD.Thus, this pathological change could affect the diagnosis and treatment ofosteoporosis. Therefore, how to evaluate the impact of vertebral rotation onBMD values quantitatively is of great significance on accurate assessment of thedegree of osteoporosis in patients.Objective To evaluate the effect of lumbar vertebral rotation on bonemineral density measured by dual-energy X-ray absorptiometry quantitatively,assess the degree of vertebral rotation by the vertebral body image based onDXA scanning, and propose a correction method.Methods5adult cadaver lumbar spine specimens（T12~L5) werecollected. A plexiglass spine rotation platform was designed and fabricated,according to the size of the lumbar spine specimens. Then, specimens were seton the rotatable platform, and rotated from the standard posterior-anterior (PA)position to45degrees with an increment of5degrees each time, clockwise andanti-clockwise respectively. Meanwhile, the BMD data was measured by DXA,and took the average values of each angle. At the same time, the images weretaken by X-ray according to the normal procedures. The grades of vertebralrotation were evaluated with the Nash-Moe method, by scanning images ofDXA and X-ray respectively. The statistics were processed with the StatisticalProduct and Service Solutions software17.0.Results The degree of rotation was not significantly associated with BMC.However, it showed a positive correlation between the degree of rotation and theprojection area, and a negative one between the degree of rotation and the BMD.Compared with the zero one, when the degree reached to15degrees, themeasured BMD displayed significant difference; moreover, the measured BMD was21%lower than the real one at45degrees. And the rate of consistent was90%, when the rotations of vertebrae were evaluated using the Nash-Moemethod by images of DXA and X-ray respectively.Conclusion The results implied lumbar vertebral rotation could lead tothe measured BMD significantly lower than the real one. So the measured dataof patients with spinal rotation deformity should be corrected when theyundergo BMD measurement by dual-energy X-ray absorptiometry, in order toget rid of overestimate the osteoporosis situation. |
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