Sorbonne Université, UPMC, CNRS UMR 7371, INSERM UMR S 1146, Laboratoire d'Imagerie Biomédicale, Paris, France.
Phys Med Biol. 2018 Jun 12;63(12):125010. doi: 10.1088/1361-6560/aac784.
Current clinical ultrasound scanners cannot be used to image the interior morphology of bones because these scanners fail to address the complicated physics involved for exact image reconstruction. Here, we show that if the physics is properly addressed, bone cortex can be imaged using a conventional transducer array and a programmable ultrasound scanner. We provide in vivo proof for this technique by scanning the radius and tibia of two healthy volunteers and comparing the thickness of the radius bone with high-resolution peripheral x-ray computed tomography. Our method assumes a medium that is composed of different homogeneous layers with unique elastic anisotropy and ultrasonic wave-speed values. The applicable values of these layers are found by optimizing image sharpness and intensity over a range of relevant values. In the algorithm of image reconstruction we take wave refraction between the layers into account using a ray-tracing technique. The estimated values of the ultrasonic wave-speed and anisotropy in cortical bone are in agreement with ex vivo studies reported in the literature. These parameters are of interest since they were proposed as biomarkers for cortical bone quality. In this paper we discuss the physics involved with ultrasound imaging of bone and provide an algorithm to successfully image the first segment of cortical bone.
当前的临床超声扫描仪无法用于成像骨骼的内部形态，因为这些扫描仪无法解决精确图像重建所涉及的复杂物理问题。在这里，我们表明，如果正确解决物理问题，使用传统换能器阵列和可编程超声扫描仪可以对骨皮质进行成像。我们通过扫描两名健康志愿者的桡骨和胫骨，并将桡骨的厚度与高分辨率外周 X 射线计算机断层扫描进行比较，为该技术提供了体内证据。我们的方法假设介质由具有独特弹性各向异性和超声波速度值的不同均匀层组成。通过在相关值范围内优化图像清晰度和强度，可以找到这些层的适用值。在图像重建算法中，我们使用射线追踪技术考虑层之间的波折射。皮质骨中超声速度和各向异性的估计值与文献中报道的离体研究一致。这些参数很有趣，因为它们被提议作为皮质骨质量的生物标志物。本文讨论了与骨超声成像相关的物理问题，并提供了成功成像皮质骨第一段的算法。
