Validation of a New Point-of-Care Calcaneal Ultrasound Densitometer (BeeTLe)

Abstract Introduction Dual-energy X-ray absorptiometry (DXA) represents the gold standard for measuring bone mineral density (BMD). However, its size and bulkiness limit its use in mass screening. Portable and easily accessible instruments are more suitable for this purpose. Materials and Methods We conducted a study to assess the repeatability, sensitivity, accuracy, and validation of a new ultrasound densitometer for the calcaneus (BeeTLe) compared to standard DXA. BMD (g/cm2) was measured at the femoral and lumbar spine levels using DXA (iLunar General Electric), and the Bone Quality Index (BQI, a dimensionless measure of bone quality) was measured with BeeTLe in patients attending the osteoporosis clinic at two bone specialist centers. The Bland-Altman test and simple linear regression were used to evaluate the association between values measured with the two instruments. Additionally, the ability of the T-score calculated with BeeTLe to identify patients with previous osteoporotic fractures was tested using ROC curves. Results A total of 201 patients (94.5% females) with a mean age of 62.1 ± 10.2 were included in the study. The BeeTLe instrument showed a coefficient of variation (CV, in 23 repeated measurements) of 1.22%, which was not statistically different from the CV of DXA (1.20%). Figure 1 shows the regression curves between BQI and BMD at the femoral neck (r2 0.500, p < 0.0001), total femur (r2 0.545, p < 0.0001), and lumbar spine (r2 0.455, p < 0.0001). Figure 2 displays the Bland-Altman plot for T-score differences at various sites. Figure 3 presents the ROC curves describing the ability of BeeTLe and DXA at different sites to classify patients with fractures vs. non-fractured (AUC not significantly different). Conclusion In this preliminary study, BeeTLe, a new point-of-care ultrasound densitometer, demonstrated good repeatability and performance similar to DXA. Therefore, its use can be proposed in screening for osteoporosis.