Globally, osteoporosis has become recognized as an important public health problem because of the fractures related to disease characterized by low bone mass, leading to decrease the bone strength as defined by the World Health Organization (WHO) which significantly increase the risk of mortality, expenditure and both direct/indirect medical treatment 1, 2, 3. Generally, the diagnosis of osteoporosis can be made in advanced stages or following after traumatic bone fracture. When the fracture occurs, its frequently enhances the risk of subsequent fractures. So, the health expectations among elderly were improved in prevention and early detection of osteoporosis with the appropriate procedure 4. Presently, the various techniques to diagnose bone mass are rapidly improving, the measurement of bone mineral density (BMD) is one of the methods that can be used to identify the risk of osteoporosis 5,6. The most well-established technique and gold standard for evaluating the BMD based on WHO criteria is Dual-energy X-ray absorptiometry (DXA) which benefits by being non-invasive with high precision measurements at various sites 7, 8, 9. However, health issues remain problematic with underdiagnosed osteoporosis cause by a low accessibility to DXA due to the inadequate resources universally available, limitations by the procedure and device cost, lack of transportation and qualified operators all not meeting the growing demand 1,3,9,10. Due to the access limitations of DXA under-diagnosis of osteoporosis has become widespread 2. Therefore, many investigators search for lower cost machine alternatives to DXA for the screening of osteoporosis 2.

An alternative technology for assessing the bone mass is to use the Quantitative ultrasound (QUS). It became an attractive candidate to primary care of osteoporosis diagnosis because it is inexpensive, does not need a specific room, is portable, ionizing radiation free, fast and easy to handle 1,5,6. Moreover, the QUS can be report both quality and quantity of bone structure while the DXA can indicate only a calcium content. According to the advantages and site selection of the QUS machine, it could compensate for the contraindications in DXA such as in pregnancy or children 7. Gluer et al., 11 studied 1,265 European women and measured from both calcaneus QUS and spine/femur DXA. Based on the results, calcaneal QUS measurements showed the fractures prediction as well as central DXA measurements. Moreover, a preliminary data summary from Gluer et al., showed the QUS method for calcaneal measurements seem to provide better performance compared with other sites 12. Nevertheless, based on the uncertainties and lack of consensus of QUS measurements, the possibility of using QUS instead of DXA is limited 1,3. Instead of using the QUS in diagnostic purposes, the benefit of QUS might be mainly contributed to a prescreen method to separate patients that should be followed up with DXA and restrict people with low risk of osteoporosis, saving unnecessary medical expenditures 1,3,4. To achieve this purpose, the device should have a high sensitivity and specificity to identify the diseases comparable with a standard device 1,3. Moreover, several studies showed that calcaneal QUS must be calibrated with a standard device and validated on the intended populations based on device-specific factors to overcome tremendous variations 3,4,12.

The aim of our study was to assess the BMD values differences between two instruments, the DXA (GE healthcare, Lunar prodigy, Japan) measuring at hips and spine, and the QUS (Hitachi, ALOKA AOS-100SA, Japan) measuring at calcaneus. This experiment could determine the correlation between the DXA and QUS value allowing the possibility to establish a calibration factor (CF) for the calcaneus QUS when compared to spine and hip DXA. Our contention is that if differences of more than 5%, they a CF should be applied to improve the diagnostic efficacy of QUS bone mass examinations. Therefore, the determination of osteoporosis sensitivity and specificity measured by the QUS machine with applied and non-applied CF were also included in this study when compared with the standard method DXA. After calibrating with DXA, QUS might be serve as a potential prescreening tool for osteoporosis as an academic service without fees for the low-income groups, alternative method for low risk of osteoporosis groups, especially in poorer areas and in less developed countries.