Dencks Stefanie, Barkmann Reinhard, Padilla Frédéric, Haïat Guillaume, Laugier Pascal, Glüer Claus-C
Medizinische Physik, Klinik für Diagnostische Radiologie, Universitätsklinikum Schleswig Holstein, Kiel, Germany.
Ultrasound Med Biol. 2007 Jun;33(6):970-80. doi: 10.1016/j.ultrasmedbio.2006.12.002. Epub 2007 Apr 18.
To estimate osteoporotic fracture risk, several techniques for quantitative ultrasound (QUS) measurements at peripheral sites have been developed. As these techniques are limited in the prediction of fracture risk of the central skeleton, such as the hip, we are developing a QUS device for direct measurements at the femur. In doing so, we noticed the necessity to improve the conventional signal processing because it failed in a considerable number of measurements due to multipath transmission. Two sets of excised human femurs (n = 6 + 34) were scanned in transmission mode. Instead of using the conventional methods, the radio-frequency signals were processed with the continuous wavelet transform to detect their time-of-flights for the calculation of speed-of-sound (SOS) in bone. The SOS-values were averaged over a region similar to the total hip region of dual X-ray absorptiometry (DXA) measurements and compared with bone mineral density (BMD) measured with DXA. Testing six standard wavelets, this algorithm failed for only 0% to 6% of scan in test set 1 compared with 29% when using conventional algorithms. For test set 2, it failed for 2% to 12% compared with approximately 40%. SOS and BMD correlated significantly in both test sets (test set 1: r2 = 0.87 to 0.92, p < 0.007; test set 2: r2 = 0.68 to 0.79, p < 0.0001). The correlations are comparable with correlations recently reported. However, the number of evaluable signals could be substantially increased, which improves the perspectives of the in vivo measurements.
为了评估骨质疏松性骨折风险，已开发出多种在外周部位进行定量超声（QUS）测量的技术。由于这些技术在预测髋部等中轴骨骼的骨折风险方面存在局限性，我们正在开发一种用于在股骨处直接测量的QUS设备。在此过程中，我们注意到有必要改进传统的信号处理方法，因为由于多径传输，它在相当数量的测量中失败了。对两组切除的人体股骨（n = 6 + 34）进行了透射模式扫描。代替使用传统方法，利用连续小波变换对射频信号进行处理，以检测其飞行时间，从而计算骨中的声速（SOS）。将SOS值在与双能X线吸收法（DXA）测量的全髋区域相似的区域上进行平均，并与用DXA测量的骨密度（BMD）进行比较。测试六种标准小波，与使用传统算法时的29%相比，该算法在测试集1中的扫描失败率仅为0%至6%。对于测试集2，其失败率为2%至12%，而传统算法约为40%。在两个测试集中，SOS和BMD均显著相关（测试集1：r2 = 0.87至0.92，p < 0.007；测试集2：r2 = 0.68至0.79，p < 0.0001）。这些相关性与最近报道的相关性相当。然而，可评估信号的数量可以大幅增加，这改善了体内测量的前景。
