Wear K A
Center for Devices & Radiol. Health, Silver Spring, MD, USA.
IEEE Trans Ultrason Ferroelectr Freq Control. 2008 Jul;55(7):1473-9. doi: 10.1109/TUFFC.2008.822.
Although calcaneal speed of sound (SOS) is an effective predictor of osteoporotic fracture risk, clinical SOS measurements exhibit a high degree of inter-system variability. Calcaneal SOS is usually computed from time-of-flight measurements of broadband ultrasound pulses that propagate through the foot. In order to minimize the effects of multi-path interference, many investigators measure time-of-flight from markers near the leading edge of the pulse. The calcaneus is a highly attenuating, highly inhomogeneous bone that distorts propagating ultrasound pulses via frequency-dependent attenuation, reverberation, dispersion, multiple scattering, and refraction. This pulse distortion can produce errors in leading-edge transit-time marker-based SOS measurements. In this paper, an equation to predict dependence of time-domain SOS measurements on system parameters (center frequency and bandwidth), transit-time marker location, and bone properties (attenuation coefficient and thickness) is validated with through-transmission measurements in a bone-mimicking phantom and in 73 women in vivo, using a clinical bone sonometer. In order to test the utility of the formula for suppressing system dependence of SOS measurements, a wideband laboratory data acquisition system was used to make a second set of through-transmission measurements on the phantom. The compensation formula reduced system-dependent leading-edge transit-time marker-based SOS measurements in the phantom from 41 m/s to 5 m/s and reduced average transit-time marker-related SOS variability in 73 women from 40 m/s to 10 m/s. The compensation formula can be used to improve standardization in bone sonometry.
尽管跟骨声速（SOS）是骨质疏松性骨折风险的有效预测指标，但临床SOS测量显示出高度的系统间变异性。跟骨SOS通常根据在足部传播的宽带超声脉冲的飞行时间测量值来计算。为了尽量减少多径干扰的影响，许多研究人员测量脉冲前沿附近标记的飞行时间。跟骨是一种高度衰减、高度不均匀的骨骼，它通过频率依赖性衰减、混响、色散、多次散射和折射使传播的超声脉冲发生畸变。这种脉冲畸变会在基于前沿渡越时间标记的SOS测量中产生误差。在本文中，通过在仿骨体模和73名体内女性中使用临床骨超声仪进行穿透传输测量，验证了一个预测时域SOS测量值对系统参数（中心频率和带宽）、渡越时间标记位置以及骨特性（衰减系数和厚度）依赖性的方程。为了测试该公式抑制SOS测量系统依赖性的效用，使用宽带实验室数据采集系统在体模上进行了第二组穿透传输测量。补偿公式将体模中基于前沿渡越时间标记的与系统相关的SOS测量值从41米/秒降低到5米/秒，并将73名女性中与渡越时间标记相关的SOS平均变异性从40米/秒降低到10米/秒。该补偿公式可用于提高骨超声测量的标准化程度。
