REAL TIME VISUALIZATION TECHNIQUE OF IN VIVO CANCELLOUS BONE AND ESTIMATION SYSTEM OF MECHANICAL INTEGRITY

随着越来越多的人达到更高的年龄，临床医生、科学家和家庭医生对骨质疏松症产生了越来越大的兴趣。昂贵的DXA（双能x射线吸收计）骨密度仪可以扫描骨骼，给出准确的骨密度读数，但这是有害的，因为x射线暴露。到目前为止，还没有令人满意的筛选程序。因为骨质疏松的改变最初出现在松质骨，只有在晚期才会发现皮质变薄。因此，我们必须开发一种廉价且无创的方法来评估体内骨密度（BMD）及其结构，它可以直接关系到骨折发生率、小梁密度和方向以及松质骨的结构相关强度。在本报告中，提出了一种利用超声检查来可视化体内骨结构及其强度的新方法，可以从机械完整性的角度来诊断骨质疏松症。结果表明：1)建立了一种利用超声医疗装置线阵列探头的真实信号可视化松质骨和骨髓的信号处理新方法；引入了反射信号和阈值的数值表达式，然后以小尺寸像素（0.18 x 0.2 mm）绘制了二维骨结构。2)根据体积密度检测出的最合适的阈值，骨为0.89 ~ 0.96，人工陶瓷泡沫试样、堇青石为~ 1.16。在体内的松质骨已提出使用超声检测和有限元分析可视化结构。这些结果将有助于开发一种实用的设备，对脚跟骨进行实时和三维可视化。

With more people than ever reaching greater age, clinicians, as well as scientists and family doctors, have developed an increasing interest in osteoporosis. Expensive machines called DXA (dual energy x-ray absorptiometry) densitometers can scan bones to give an accurate reading of bone density, but this is harmful due to X-ray exposure. As yet, there is no satisfactory screening procedure. Because osteoporotic changes appear initially in the cancellous bone and it is only at an advanced stage that cortical thinning is detected. Thus, we must develop methods to inexpensively and non-invasively assess the in vivo bone mineral density (BMD) and its structure which can directly relate to fracture incidence, trabecular density and orientation, and architecture-related strength of cancellous bone. In the present report, a new method for visualizing in vivo bone architecture and its strength using ultrasound inspection is proposed, which can allow diagnose of osteoporosis from the viewpoint of mechanical integrity. The results are summarized as follows:1) A new signal processing procedures to visualize bone and bone marrow of cancellous bone has been established using the real signals from a linear array type probe of ultrasonic medical devise; a numerical expression for the reflected signal and threshold value were introduced, then 2D bone architecture was drawn by small size of pixel, 0.18 x 0.2 mm.2) The most suitable threshold value examined which was based on the bulk density to create architecture was 0.89〜0.96 for bone, and 〜1.16 for artificial ceramic foam specimen, cordierite,3) An estimation method of mechanical integrity, fracture risk, of in vivo cancellous bone has been proposed using ultrasound testing and finite element analysis for visualized architecture.Those results would allow development of a practical device of real time and 3-D visualization for heel bone.