Effects of structural anisotropy of cancellous bone on speed of ultrasonic fast waves in the bovine femur

• Published in: IEEE transactions on ultrasonics, ferroelectrics, and frequency control Vol. 55; no. 7; pp. 1480 - 1487
• Main Authors: Mizuno, K., Matsukawa, M., Otani, T., Takada, M., Isao Mano, Tsujimoto, T.
• Format: Journal Article
• Language: English
• Published: United States IEEE 01-07-2008; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Animals; Anisotropic magnetoresistance; Anisotropy; Attenuation; Bones; Bovine; Bovine femurs; Cancellous bone; Cattle; Computed tomography; Computer Simulation; Elastic Modulus; Elasticity Imaging Techniques - methods; Femur; Femur - diagnostic imaging; Femur - physiology; Image Interpretation, Computer-Assisted - methods; Magnetic resonance imaging; Models, Biological; Orientation; Osteoporosis; Propagation; Reproducibility of Results; Scattering, Radiation; Sensitivity and Specificity; Slow waves; Stress, Mechanical; Studies; Ultrasonic imaging; Ultrasonic variables measurement; Wave propagation; X-ray imaging; X-rays
• ISSN: 0885-3010; 1525-8955
• DOI: 10.1109/TUFFC.2008.823

Ultrasonic waves in cancellous bone change dramatically depending on its structural complexity. One good example is the separation of an ultrasonic longitudinal wave into fast and slow waves during propagation. In this study, we examined fast wave propagation in cancellous bone obtained from the head of the bovine femur, taking the bone structure into consideration. We investigated the wave propagation perpendicular to the bone axis and found the two-wave phenomenon. By rotating the cylindrical cancellous bone specimen, changes in the fast wave speed due to the rotation angle then were observed. In addition to the ultrasonic evaluation, the structural anisotropy of each specimen was measured by X-ray micro-computed tomography (CT). From the CT images, we obtained the mean intercept length (MIL), degree of anisotropy (DA), and angle of insonification relative to the trabecular orientation. The ultrasonic and CT results showed that the fast wave speed was dependent on the structural anisotropy, especially on the trabecular orientation and length. The fast wave speeds always were higher for propagation parallel to the trabecular orientation. In addition, there was a strong correlation between the DA and the ratio between maximum and minimum speeds (V max /V min ) (R 2 = 0.63).