| Research Abstract |
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.
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