Visualisation Technique for Trabecular Architecture of Bone Using Ultrasound Signals

摘要

We have proposed a new technique for visualising trabecular architecture of spongy bone using ultrasound A-mode signals from a transducer of medical ultrasound system. The technique can be established by finding a method to distinguish between bone and bone marrow. Firstly, the A-mode signal intensity was fitted by the form, A=A_0exp(-αx), where A, A_0, α, and x represent echo intensity, initial value of echo, attenuation factor, and distance, respectively. Then the curve was moved slightly downward or upward by multiplying with the coefficient k (0.9～1.2), and it was used as an index line to distinguish between bone and bone marrow. To clarify the validity of the proposed technique, we examined bovine bone specimen and a spongy-shaped specimen made by ceramics. The pixel size for creating architecture was 0.2 (width)×0.15 (depth) mm for bone marrow and 0.2 × 0.3 mm for bone substance, and the pixel size differs due to the difference in wave speeds. The visualisation technique was capable to create an image size of ～10 mm depths from the surface of cortical bone. We also tried to visualise the heel bone.