Frequency and resolution dependence of the anisotropic impedance estimation in cortical bone using time-resolved scanning acoustic microscopy
✍ Scribed by Kay Raum; Jan Reißhauer; Jörg Brandt
- Publisher
- John Wiley and Sons
- Year
- 2004
- Tongue
- English
- Weight
- 420 KB
- Volume
- 71A
- Category
- Article
- ISSN
- 1549-3296
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
The influences of frequency and spatial resolution on the anisotropic impedance estimation of cortical bone was investigated in the frequency range 25–100 MHz. A set of spherically focused transducers provided a spatial resolution in the range from 150 down to about 20 μm. Four embedded cortical bone samples (two male, two female, two donors aged <30 years, two donors aged >70 years) were cut with different orientations relative to the long axis of the femur (0–90°). From each section, impedance maps were acquired in the C‐scan mode. Histogram evaluations showed a similar angular dependence with a characteristic off‐axis maximum of the estimated impedance for all samples and frequencies. The impedance values obtained with the 25‐MHz transducer were significantly lower than those obtained with the 50‐ and 100‐MHz transducers. Morphological parameters of the macrostructure, for example, size and distribution of the haversian channels and the resulting porosity, were estimated from the high‐resolution acoustic images. These structures appeared to have a significant influence on the measured properties of the bone matrix for the low‐frequency and low‐aperture measurements. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 71A: 430–438, 2004