Bone microstructure and elastic tissue properties are reflected in QUS axial transmission measurements.
Accurate clinical interpretation of the sound velocity derived from axial transmission devices requires a detailed understanding of the propagation phenomena involved and of the bone factors that have an impact on measurements. In the low megahertz range, ultrasonic propagation in cortical bone depends on anisotropic elastic tissue properties, porosity and the cortical geometry (e.g., thickness). We investigated 10 human radius samples from a previous biaxial transmission study using a 50-MHz scanning acoustic microscope (SAM) and synchrotron radiation microcomputed tomography. The relationships between low-frequency axial transmission sound speed at 1 and 2 MHz, structural properties (cortical width Ct.Wi, porosity, Haversian canal density and material properties (acoustic impedance, mineral density) on site-matched cross-sections were investigated. Significant linear multivariate regression models (1 MHz: R(2) = 0.84, p < 10(-4), root-mean-square error (RMSE) = 38 m/s, 2 MHz: R(2) = 0.65, p < 10(-4), RMSE = 48 m/s) were found for the combination of Ct.Wi with porosity and impedance. A new model was derived that accounts for the nonlinear dispersion relation with Ct.Wi and predicts axial transmission velocities measured at different ultrasonic frequencies (R(2) = 0.69, p < 10(-4), RMSE = 52 m/s).
Raum
Kay
K
Laboratoire d'Imagerie Paramétrique, CNRS/Université Paris 6, Paris, France. kay.raum@medizin.uni-halle.de
Leguerney
Ingrid
I
Chandelier
Florent
F
Bossy
Emmanuel
E
Talmant
Maryline
M
Saïed
Amena
A
Peyrin
Françoise
F
Laugier
Pascal
P
D000368:Aged; D000369:Aged, 80 and over; D015519:Bone Density; D001842:Bone and Bones / Q000000981:diagnostic imaging* / Q000502:physiology; D004548:Elasticity; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008297:Male; D033401:Microscopy, Acoustic; D015233:Models, Statistical; D016062:Porosity; D011884:Radius / Q000000981:diagnostic imaging / Q000502:physiology; D014057:Tomography, X-Ray Computed