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ABSTRACT: Longitudinal wave in cancellous bone separates into fast and slow waves depending on the alignment of trabeculae. Here, the fast wave mainly propagates in trabeculae, whereas slow wave propagates in the soft tissue (bone marrow). Because these two waves usually overlap, the evaluation of each wave has still remained difficult. In this study, then, we have tried to evaluate the wave properties (attenuation and velocity), making use of the plane wave in an acoustic tube. 3-D image of the bone specimen was obtained by X-ray micro CT. In an acoustic tube, a cancellous bone specimen was set between home-made PVDF transducers. A function generator delivered a single sinusoidal signal in the range of 0.5 to 1.5 MHz to the transmitter. By filing a part of bone specimen away, we have tried to obtain the attenuation and velocity of the specimen. The two wave phenomenon clearly occurred in our specimen. In some trabecular bones of big animals, the wave separated perfectly. We have then tried to obtain ultrasonic properties of both waves and investigated the reflection and transmission at the interfaces.
The Journal of the Acoustical Society of America 04/2012; 131(4):3460. · 1.55 Impact Factor
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ABSTRACT: The influence of cancellous bone microstructure on the ultrasonic wave propagation of fast and slow waves was experimentally investigated. Four spherical cancellous bone specimens extracted from two bovine femora were prepared for the estimation of acoustical and structural anisotropies of cancellous bone. In vitro measurements were performed using a PVDF transducer (excited by a single sinusoidal wave at 1 MHz) by rotating the spherical specimens. In addition, the mean intercept length (MIL) and bone volume fraction (BV/TV) were estimated by X-ray micro-computed tomography. Separation of the fast and slow waves was clearly observed in two specimens. The fast wave speed was strongly dependent on the wave propagation direction, with the maximum speed along the main trabecular direction. The fast wave speed increased with the MIL. The slow wave speed, however, was almost constant. The fast wave speeds were statistically higher, and their amplitudes were statistically lower in the case of wave separation than in that of wave overlap.
The Journal of the Acoustical Society of America 11/2010; 128(5):3181-9. · 1.55 Impact Factor
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ABSTRACT: The ultrasonic wave propagation of fast and slow waves was investigated in vitro in 35 cubic cancellous bone specimens extracted from human femoral heads. Measurements were performed in three orthogonal directions using home-made PVDF transducers excited by a single sinusoidal wave at 1 MHz. The apparent density of the specimens was measured. Two separated fast and slow waves were clearly observed in 16 specimens, mainly in the main load direction. The waveforms and the sound speeds of fast and slow waves were similar to the reported data in bovine bone. The group of specimens in which the two waves were observed did not exhibit statistically higher apparent density than the rest of the specimens, but did exhibit statistically higher acoustic anisotropy ratio. The speeds in the main load direction were higher than those in the other direction. The fast and slow wave speeds were in good agreement with Biot's model, showing an increase with bone volume fraction (BV/TV). The ratio of peak amplitudes of the fast and slow waves nonlinearly increased as a function of BV/TV. These results open interesting perspective for acoustic assessment of cancellous bone micro-architecture and especially anisotropy that might lead to an improved assessment of bone strength.
The Journal of the Acoustical Society of America 06/2009; 125(5):3460-6. · 1.55 Impact Factor
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ABSTRACT: The ultrasonic longitudinal wave in the cancellous bone is separated into two waves, fast and slow waves [1]. In this study, the relationship between the fast wave speed and the cancellous bone structure is experimentally investigated. A conventional ultrasonic pulse measurement was performed using a PVDF focus transmitter (Custom made, Toray) and a self-made PVDF receiver. Cylindrical specimens of cancellous bone were taken from the head of bovine femur in the distal part, along the three orthogonal directions. The distribution of fast wave speed was obtained by changing the measurement position along the cylindrical axis. The anisotropy of speed was also investigated by rotating the specimens. The structural parameters of each specimen were also measured by X-ray micro CT (MCT-12505MF, Hitachi), which gave us the trabecular length and alignment from MIL (mean intercept length) parameters through TRI3D-Bon software (Ratoc). We found that the fast wave showed large distribution and strong anisotropy depending on the measurement positions and wave propagation directions in the specimens. The fast wave showed the maximum speed in case of wave propagation along the load direction. Reference [1] A. Hosokawa and T. Otani, J. Acoust. Soc. Am., 101, 558 (1997).
The Journal of the Acoustical Society of America 06/2008; 123(5):3635. · 1.55 Impact Factor
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ABSTRACT: Effect of decreasing bone density (a symptom of osteoporosis) is greater for cancellous bone than for dense cortical bone, because cancellous bone is metabolically more active. Therefore, bone density or bone mineral density at cancellous bone is generally used to estimate the onset of osteoporosis. Elasticity or elastic constant is one of fundamental mechanical parameters and directly related to the mechanical strength of bone. Accordingly, elasticity is a preferable parameter to assess the fracture risk. A novel ultrasonic bone densitometer LD-100 has been developed to obtain mass density and elasticity of cancellous bone with a spatial resolution comparable to that of the peripheral quantitative computed tomography system. Bone mass density and bone elasticity are evaluated using ultrasonic parameters based on fast and slow waves in cancellous bone using a modeling of ultrasonic wave propagation path. Elasticity is deduced from measured bone mass density and propagation speed of fast wave. Thus, elasticity of cancellous bone is approximately expressed by a cubic equation of bone mass density.
The Journal of the Acoustical Society of America 06/2008; 123(5):3632. · 1.55 Impact Factor
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ABSTRACT: The detailed spatial distributions of longitudinal ultrasonic velocity in cortical bone specimens obtained from three bovine femoral diaphysis were experimentally investigated using a pulse-echo system. The relationship between velocity, density, bone mineral density (BMD) and microstructure was investigated. Velocity was found to vary as a function of the direction of propagation and the location of the measured specimens in the bone diaphysis. A significant correlation was found between density and velocity, and between density and BMD. In some parts with plexiform structure, clear variations in velocity anisotropy were found despite no significant difference in density, BMD and microstructure.
Ultrasonics 01/2007; 44 Suppl 1:e233-7. · 1.84 Impact Factor
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ABSTRACT: This paper reports the fabrication and characterization of ZnO piezoelectric thin films in which the crystallite c-axis is unidirectionally aligned in the plane. The films were deposited by a conventional radio frequency (RF) magnetron sputtering apparatus without epitaxy. We have measured reflection coefficient S11 of the ZnO film/glass substrate composite shear mode resonator and confirmed that the resonator excites shear wave only in the very high frequency to ultra high frequency ranges (VHF-UHF). The crystallites c-axis orientation and alignment were determined by x-ray diffraction (XRD) patterns, phi-scan pole figure analysis, omega-scan rocking curves, and atomic force microscope (AFM) measurement. The transduction of the shear wave showed good agreement with properties of the crystallite alignment in the film.
IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control 12/2005; 52(11):2140-5. · 1.69 Impact Factor
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Takahiko Otani
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ABSTRACT: Ultrasonic measurements of bone status or bone mass density are generally performed using ultrasonic parameters consisting of the slope of frequency-dependent attenuation (or broadband ultrasound attenuation: BUA) and the speed of sound (SOS). Many results of in vitro laboratory measurements and in vivo clinical trials have shown the ultrasonic parameters, BUA and SOS correlate significantly with the bone mass density measured by X-ray method. However, there exists some problem inherent in the ultrasonic method on the reproducibility and the uncertainty of measured ultrasonic parameters. The ultrasonic properties of cancellous bone have been experimentally and theoretically studied by author's group to reveal problems inherent in the ultrasonic method. According to experimental and theoretical studies, two longitudinal waves, fast wave and slow wave are clearly observed. The propagation speed of the fast wave increases with the bone density and that of the slow wave decreases very slightly with the bone density. Whereas the attenuation constant of the fast wave is much higher than that of the slow wave and is almost independent of the bone density, but in contrast, the attenuation constant of the slow wave increases considerably with the bone density. Experimental results on transmitted ultrasonic wave through cancellous bone show that the amplitude of the slow wave decreases with the bone density and the amplitude of the fast wave, on the contrary, increases with the bone density. This dependence of the fast wave amplitude on the bone density can not be explained by the attenuation constant. The ultrasonic wave propagation path through cancellous bone is modelized to clarify the propagation phenomenon and to specify the causality between ultrasonic wave parameters and the bone density. The bone density is quantitatively formulated based on the modelization as a function of the amplitude and the propagation speed of the fast wave.
Clinical calcium 01/2005; 14(12):69-75.
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ABSTRACT: A Brillouin scattering technique has been applied to investigate the ultra-drawing process of polypropylene films. The gradual elastic changes during the drawing process showed the appearance of anisotropy and birefringence of the sample. Devising the optical geometry of Brillouin scattering measurement, continuous changes of the birefringence during ultra-drawing were clearly observed. These data were compared with the data obtained using a polarizing microscope, which were acquired at specific points of the drawing process.
Japanese Journal of Applied Physics 01/2003; 42:3080-3083. · 1.06 Impact Factor
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ABSTRACT: Ultrasonic wave properties (attenuation and velocity) in the particle compounded agarose gels have been experimentally studied in the range from 1 to 30 MHz. The particles used were talc, glass beads and graphite. The effects of size and volume concentration of particles were clearly observed as changes of ultrasonic wave properties. Applying the Urick's theory for viscous liquid suspensions, the specific curves of velocity in the gels were observed as a function of a beta, where a is the radius of the particles and beta is described by angular frequency omega, density rho and fluid viscosity eta. This indicates that the particle behavior in the gels seems to be similar with that in the viscous fluid. The estimated eta in the gels was higher than that of the free water, showing the high viscosity in the gels.
Ultrasonics 06/2002; 40(1-8):323-7. · 1.84 Impact Factor
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秀夫 片岡,
真美 松川,
隆彦 大谷,
雄 大和,
薫 山崎,
昭 長野,
Hideo KATAOKA,
Mami Matsukawa, Takahiko Otani,
Yu Yamato,
Kaoru Yamazaki,
Akira Nagano
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ABSTRACT: rights: 社団法人電子情報通信学会 rights: 本文データは学協会の許諾に基づきCiNiiから複製したものである relation：isVersionOf: http://ci.nii.ac.jp/naid/110003174532/ 超音波による骨粗鬆症診断法を確立するためには,骨構造と超音波特性の関係を把握することが重要である.本研究ではヒト大腿骨頚部皮質骨と牛大腿骨皮質骨について,形態学的評価による構造と音速の関係を検討した.管状皮質骨の管径方向の音速を測定した結果,I)皮質骨(ヒト)中の音速と間隙率に相関関係があること,II)皮質骨(牛)内に音速分布があること,III)皮質骨(牛)の構造により音速が変化すること,がわかった. In order to diagnose osteoporosis by ultrasonic waves, it is important to clarify the relation between bone structures and acoustical characteristics. In this study, we have compared structures of cortical bone with ultrasonic wave velocity, using specimens which were obtained from human femoral neck and bovine femur. The results from ultrasonic wave propagation in the radial direction of the bone are summarized as follows. I) There is a clear correlation between wave velocity and Intracortical Porosity (ICP) in case of human cortical bone. II) Wave velocity depends on the measured part of the bone in case of Bovine cortical bone. III) Due to the structure, wave velocity shows difference in case of bovine cortical bone.
