OBJECTIVE: To study the interchangeability of the bone mineral density results between Hologic® dual energy x-ray absorptiometry (DEXA) and Cromox® computed dual energy conventional x-ray absorptiometry (CDEXA) equipments. MATERIALS AND METHODS: Thirty-eight femoral necks and 31 lumbar spines of 43 patients underwent bone mineral density measured by both equipments in a diagnostic imaging center. The Cromox® equipment was calibrated with a reference Cromox® phantom for bone absorptiometry. RESULTS: A strong correlation between results obtained from the two devices was found for each skeletal site. The linear correlation coefficient measured for the right femoral neck was r = 0.920, p < 0.0001, and r = 0.923, p < 0.0001 for the lumbar spine L2-L4 vertebrae. Considering the relevance of the Tscore result in the clinical practice for bone densitometry, the mean difference of the Tscore between devices was calculated, resulting in an arithmetic mean DTscore = 0.191 for hips and an arithmetic mean DTscore = 0.228 for the lumbar spines. The skeletal status is established according to the World Health Organization definition as normal, osteopenia or osteoporosis. The skeletal status concordance between devices was higher than 76% for hips and higher than 77% for spines; and higher than 96% when considering concordance in at least one of the two sites. CONCLUSION: The linear correlation coefficients obtained are very close to the international references among gold standard devices, reported as r > 0.95. For both sites, the arithmetic mean difference in Tscore between devices is low - least than the lowest significant variance.
Dual energy x-ray absorptiometry; Dual energy radiographic absorptiometry; Computed x-ray densitometry; Correlation; Interchangeability
