Lateral dual-photon absorptiometry: A new technique to measure the bone mineral density at the lumbar spine

Abstract

Bone mineral density (BMD) measurement of the lumbar spine by dual-photon absorptiometry (DPA) using a radioactive source and more recently an x-ray tube (DEXA) is a useful noninvasive technique to assess bone loss in vertebral osteoporosis. Because an anteroposterior (AP) projection is used, DPA measures not only the mainly trabecular bone of the vertebral body but also the cortical bone of the posterior processes, which does not contribute to the development of crushed fractures. Using a DPA apparatus equipped with a 153 Gd source coupled with an 18-detector system that provides better collection efficiency for the narrow beam of 153 Gd radiation, we have developed a technique measuring the BMD of the vertebral body of L2, L3, and L4 on a lateral projection based on previous studies using radiographic photodensitometry for lateral spine. The precision of the method-1.7% in vivo and 0.88% in vitro-is similar to that obtained with the AP projection (respectively, 1.7 and 1.0%). Lateral BMD decreased with age in 143 normal women and was best accounted for by a cubic curve (r = -0.51, p less than 0.001). The age-related bone loss between 30 and 80 years of age was much higher with the lateral (-44%) than with the AP (-22%) projection, a pattern consistent with the greater trabecular than cortical age-related bone loss. When osteoporotics (OP) were compared to age-matched normal women, the decreased in BMD was larger with the lateral (-30%) than with the AP projection (-23%), but in terms of Z scores, no difference could be found between both projections.(ABSTRACT TRUNCATED AT 250 WORDS)

Normal Changes in Spinal Bone Mineral Density in a Chinese Population: Assessment by Quantitative Computed Tomography and Dual-Energy X-ray Absorptiometry

“…Correlation coefficients between BMD measurements in our study (Table 7) were similar to previous results by other reports [5,[27][28][29][30]. The lower correlation between QCT and PA-DXA compared with the lateral scanning techniques can be explained by the inclusion of the posterior elements in the PA-DXA technique.…”

Bone mineral density of the hip measured with dual-energy X-ray absorptiometry in normal elderly women and in patients with hip fracture

“…The high incidence of aortic calcifications and of arthrosis of the lumbar spine in the elderly is likely to be responsible for this discrepancy, as it will artifically increase the bone mineral content of the spine in the elderly. Because spinal radiography was not 247 performed, we cannot directly verify this hypothesis; this explanation, however, is supported by our recent data obtained with lateral OPA of the spine, a technique which allows restriction of the measurement to the lumbar vertebral body, excluding the posterior arch and the projection of aortic calcification [22]. With such a technique, we have found and age-related bone loss 22% higher than with the frontal incidence, and we have shown that a mild to moderate osteoarthritis of the posterior arch results in a 13% increase of the BMO of the spine.…”

Single and dual energy X-ray absorptiometry

“…This limits the usefulness and sensitivity of PA spinal DXA in the elderly population in whom such degenerative changes will commonly be present ( > 60 %) at age 70 years or more. This has led to the development of lateral DXA scanning of the lumbar spine [80][81][82][83] (Fig. 3).…”