Optimal Prediction of Bone Mineral Density with Ultrasonic Measurements in Excised Human Femur

Abstract

Bone mineral density (BMD) measured with dual energy X-ray absorptiometry (DXA) techniques is the current gold standard for osteoporotic fracture risk prediction. Quantitative ultrasound (QUS) techniques in transmission measurements are, however, increasingly recognized as an alternative approach. It is feasible to select different QUS methods, one type being optimized to assess microarchitectural properties of bone structure and another to assess BMD. Broadband ultrasonic attenuation (BUA) and ultrasonic velocity (UV) measured on the proximal human femur have been shown to be both significantly correlated with BMD. However, a great diversity of algorithms has been reported to measure the time-of-flight used to derive UV values. The purpose of this study was to determine which procedure results in the optimal BMD prediction at the proximal femur from ultrasound measurements. Thirty-eight excised human femurs were measured in transmission with a pair of focused 0.5-MHz central frequency transducers. Two-dimensional scans were performed and radiofrequency (RF) signals were recorded digitally at each scan position. BUA was estimated and eight different signal processing techniques were performed to estimate UV. For each signal-processing technique UV was compared to BMD. We show that the best prediction of BMD was obtained with signal-processing techniques taking into account only the first part of the transmitted signal (r2BMD-SOS = 0.86). Moreover, we show that a linear multiple regression using both BUA and speed of sound (SOS) and applied to site-matched regions of interest improved the accuracy of BMD predictions (r2BMD-SOS/BUA = 0.95). Our results demonstrate that selecting specific signal-processing methods for QUS variables allows optimal assessment of BMD. Correlation is sufficiently high that this specific QUS method can be considered as a good surrogate of BMD.

Fast and easy preoperative estimation of cancellous bone mineral density in patients with proximal femur fractures

“…Although promising good results, sonographical methods such as speed of sound or broadband ultrasonic attenuation measurement are still in an experimental stage and not feasible to obtain local values for the proximal femur [7]. Furthermore, ultrasound techniques are highly dependent on the examiners experience.…”

“…Additionally, no osteoporotic BMD values could be detected in DXA scans in more than half of the patients with hip fractures [29]. Experimental procedures such as quantitative ultrasound [7,28] are not yet implemented in the clinical routine and well-known X-ray indices for bone quality prediction such as the Singh Index (SI) are prone to failure [8,12]. In biomechanical tests, CT data were reported to have a good informative value concerning load to failure, Young's modulus or compressive resistance [3,18].…”

Multi-site bone ultrasound measurements in elderly women with and without previous hip fractures

“…The linear combination of SOS and BUA associated strongly with the BMD (r=0.95) of intact proximal femora in vitro [13]. The same method was subsequently applied in vivo [3], and the linear combination of SOS values measured through the soft tissue, cortical bone, and trabecular region correlated significantly with the total hip BMD (r=0.85) in vivo [2].…”

Microstructural characterization of trabecular bone using ultrasonic backscattering and diffusion parameters

“…5,6 These methods provide measurements related to bone stiffness, porosity, and density. [7][8][9][10] However, the assessment of bone density alone is not enough for an early diagnosis of bone degradation. Although bone mineral density is a strong predictor of bone strength, other parameters such as trabecular microarchitecture influence bone mechanical competence.…”