Axial transmission techniques for bone assessment: an in vitro comparative study

The objective of this paper was to compare three different approaches using ultrasonic axial transmission in vitro. Forty-one fresh human radii with soft tissue removed were investigated. Measurements of ultrasound velocity of the fastest signal contribution have been performed with a commercial device (Sunlight Omnisense™, 1.25 MHz), a prototype based on 1 MHz bi-directional axial transmission, and a prototype low frequency (200 kHz) device. In addition, the low frequency probe allowed the velocity measurement of a slower wave guided by the bone. Site-matched pQCT measurements provided bone properties, such as cortical thickness, cross-sectional area, and bone mineral density (BMD). All measurements were taken at the same location which corresponds to the clinical site of measurement. Our results suggest that different axial transmission approaches may reflect different bone properties. Therefore, a multi-frequency technique might be valuable to separate respective contributions of different bone properties (e. g., cortical thickness and BMD) with measured values of velocity.