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  • Comparative Studies. Non-European Languages/Literatures  (13)
  • 1
    Online Resource
    Online Resource
    Modified transfer function with a phase rotation parameter for ultrasound longitudinal waves in cancelous bone
    Acoustical Society of America (ASA) ; 2015
    In:  The Journal of the Acoustical Society of America Vol. 138, No. 3_Supplement ( 2015-09-01), p. 1797-1797
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 138, No. 3_Supplement ( 2015-09-01), p. 1797-1797
    Abstract: The through-transmission ultrasound signal in cancelous bone consists of two longitudinal waves, called the fast and slow waves. The conventional propagation model assumes that the wavefront of an ultrasound wave passing through a bone specimen is flat and that each wave arrives simultaneously at all the points on a transducer surface. To compensate for the waveform change caused by the effect of the uneven wavefront received at a flat transducer, we propose a new transfer function modified with a phase rotation parameter. We also propose a fast decomposition method that requires only 5 seconds using a laptop personal computer. The proposed decomposition method using the modified transfer function succeeded to separate the two waves and characterize each of them accurately, where the normalized residual intensity power was less than −20 dB in the experimental study when the bone specimen thickness was from 6 to 15 mm. In the simulation study, the normalized residual power was less than −20 dB when the specimen thickness was from 3 to 8 mm. These results show that the transfer function with a phase rotation parameter is valid and that the proposed decomposition method has a great potential to provide good indicators of osteoporosis in real-time.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.4933701
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2015
    detail.hit.zdb_id: 1461063-2
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  • 2
    Online Resource
    Online Resource
    Diagnosis of heart muscle by spectrum transition estimation of heart wall vibration
    Acoustical Society of America (ASA) ; 1996
    In:  The Journal of the Acoustical Society of America Vol. 100, No. 4_Supplement ( 1996-10-01), p. 2616-2617
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 100, No. 4_Supplement ( 1996-10-01), p. 2616-2617
    Abstract: Vibration of the heart wall arises from motion due to myocardial contraction and relaxation, and thus this vibration reflects the function of the heart. The activity of the heart muscle can be estimated by investigating the spectrum transition of spatial and/or frequency spectra between vibration signals. It is difficult, however, to estimate the spectrum transition patterns of nonstationary signals, such as vibration, and to diagnose heart diseases. A new method of the estimation of spectrum transition is presented by introducing a constraint into the cost function, which is described by the partial correlation coefficients, by constraint least-squares method. By applying this method to the analysis of vibration signals, noninvasively measured by a method developed in our laboratory using ultrasonics, on the left ventricular side of the interventricular septum, the spectrum transition during a period of one beat was investigated. Furthermore, by analysis of some vibration signals on the vertical cross section of the interventricular spectrum between the right and left ventricles, the spectrum transition of the myocardial layers was investigated and the spectrum transition patterns of normal individuals and patients were clearly obtained. The establishment of this method opens up a new way of diagnosing heart diseases.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.417677
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 1996
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  • 3
    Online Resource
    Online Resource
    Ultrasonic imaging of displacements inside objects induced by continuously applied fluctuating acoustic radiation forces
    Acoustical Society of America (ASA) ; 2008
    In:  The Journal of the Acoustical Society of America Vol. 123, No. 5_Supplement ( 2008-05-01), p. 3793-3793
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 123, No. 5_Supplement ( 2008-05-01), p. 3793-3793
    Abstract: Recently, many studies are conducted to measure the response of soft tissue to applied ultrasonic acoustic radiation force. However, the change in position of a target is dominantly induced by a radiation force applied from only one direction, particularly when the target is much harder than surrounding medium. In this case, elasticity of the target cannot be evaluated because the change in position does not relate to target's elasticity. In this study, 1-MHz continuous-wave ultrasound whose envelope fluctuated at 5 Hz was used to apply the radiation force fluctuating at 5 Hz. By applying two radiation forces from two opposite horizontal directions, the object would be effectively deformed (compressed) in the horizontal direction and vertically expanded due to its incompressibility. Resultant vertical displacements were measured by ultrasonic pulses at 22 MHz in center frequency which can be easily separated from 1-MHz ultrasound by filtering. In in vitro experiments using chicken muscle and porcine liver, displacements at 5 Hz were clearly imaged. Amplitudes of displacements in liver are similar to those in muscle, whereas applied radiation force was one-fifth. Furthermore, shear wave propagating in liver was clearly visualized because liver was much softer than muscle, i.e., the wavelength was much shorter.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.2935463
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2008
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  • 4
    Online Resource
    Online Resource
    Bottom shear modulus profiler (BSMP) measurements of the shallow-water seabed geoacoustics properties in Japan
    Acoustical Society of America (ASA) ; 1989
    In:  The Journal of the Acoustical Society of America Vol. 85, No. S1 ( 1989-05-01), p. S87-S87
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 85, No. S1 ( 1989-05-01), p. S87-S87
    Abstract: The method of bottom shear modulus profiler (BSMP) was used to measure the seabed properties of several locations in Japan. In this method, the seabed admittance, which is defined as the ratio of the wave-induced particle motion to the wave pressure on the seafloor is measured [T. Yamamoto and T. Torii, Geophys. J. K. Astron. Soc. 85, 413–431 (1986)]. These data are then used as input to a linear inversion scheme for calculation of the shear modulus profile. The collected data are presented in a complete form of shear and compressional wave velocity profiles. An attempt has been made to improve the numerical analysis of the inverse method used in the BSMP software. By applying a tapering Hamming window in the truncation of the order employed in the singular value decomposition (SVD) technique, the truncated expansion equation was modified and the higher-order eigenvalues were used stably. A numerical test as well as the analysis of the data using this method is presented.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.2027188
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 1989
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  • 5
    Online Resource
    Online Resource
    Fast decomposition of two ultrasound longitudinal waves in cancellous bone using a phase rotation parameter for bone quality assessment: Simulation study
    Acoustical Society of America (ASA) ; 2017
    In:  The Journal of the Acoustical Society of America Vol. 142, No. 4 ( 2017-10-01), p. 2322-2331
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 142, No. 4 ( 2017-10-01), p. 2322-2331
    Abstract: Ultrasound signals that pass through cancellous bone may be considered to consist of two longitudinal waves, which are called fast and slow waves. Accurate decomposition of these fast and slow waves is considered to be highly beneficial in determination of the characteristics of cancellous bone. In the present study, a fast decomposition method using a wave transfer function with a phase rotation parameter was applied to received signals that have passed through bovine bone specimens with various bone volume to total volume (BV/TV) ratios in a simulation study, where the elastic finite-difference time-domain method is used and the ultrasound wave propagated parallel to the bone axes. The proposed method succeeded to decompose both fast and slow waves accurately; the normalized residual intensity was less than −19.5 dB when the specimen thickness ranged from 4 to 7 mm and the BV/TV value ranged from 0.144 to 0.226. There was a strong relationship between the phase rotation value and the BV/TV value. The ratio of the peak envelope amplitude of the decomposed fast wave to that of the slow wave increased monotonically with increasing BV/TV ratio, indicating the high performance of the proposed method in estimation of the BV/TV value in cancellous bone.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.5008502
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2017
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  • 6
    Online Resource
    Online Resource
    A phantom study on ultrasonic measurement of arterial wall strain combined with tracking of translational motion
    Acoustical Society of America (ASA) ; 2006
    In:  The Journal of the Acoustical Society of America Vol. 120, No. 5_Supplement ( 2006-11-01), p. 3270-3270
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 120, No. 5_Supplement ( 2006-11-01), p. 3270-3270
    Abstract: Correlation-based techniques are often applied to ultrasonic rf echoes to obtain the arterial wall deformation (strain). In such methods, the displacement estimates are biased due to changes in center frequency of echoes. One of the reasons for the change in center frequency is the interference of echoes from scatterers within the wall. In the phased tracking method previously proposed for strain estimation by our group, the estimated displacement contains both the components due to the translational motion and strain. The translational motion is larger than strain by a factor of 10 and, thus, the error in the estimated displacement due to the change in center frequency mainly depends on translational motion and is often larger than the minute displacement due to strain. To reduce this error, in this study, a method is proposed in which the translational motion is compensated using the displacement of the luminal boundary estimated by the phased tracking method before correlating echoes between the frame before deformation and that at the maximum deformation to estimate the strain distribution within the wall. In basic experiments using phantoms made of silicone rubber, the estimation error was much reduced to 15.6% in comparison with 36.4% obtained by the previous method.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.4777038
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2006
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  • 7
    Online Resource
    Online Resource
    Flow-mediated change in viscoelasticity of radial arterial wall measured by 22-MHz ultrasound
    Acoustical Society of America (ASA) ; 2008
    In:  The Journal of the Acoustical Society of America Vol. 123, No. 5_Supplement ( 2008-05-01), p. 3788-3788
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 123, No. 5_Supplement ( 2008-05-01), p. 3788-3788
    Abstract: The endothelial dysfunction is considered to be an initial step of atherosclerosis. Moreover, it was reported that the smooth muscle, which constructs the media of the artery, changes its characteristics due to early-stage atherosclerosis. Therefore, it is essential to develop a method for assessing the regional endothelial function and mechanical property of the arterial wall. There is an ultrasound-based conventional technique to measure the change in inner diameter of the brachial artery caused by flow-mediated dilation (FMD) after release of avascularization. In this study, the transient change in the mechanical property of the arterial wall was further revealed by measuring the stress-strain relationship during each heartbeat. For this measurement, the minute change in thickness (strain) of the radial artery was measured using the ultrasonic phased tracking method, together with the waveform of blood pressure (stress) which was continuously measured at the radial artery. From in vivo experiments, it has been founded the slope of the stress-strain hysteresis loop decreases due to FMD and the area increase depends on the ratio of elastic modulus and loss modulus (depends on viscosity). These results show a potential of the proposed method for thorough analysis of the transient change in viscoelasticity due to FMD.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.2935446
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2008
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  • 8
    Online Resource
    Online Resource
    Noninvasive measurement of motion velocity of the heart wall and its applications
    Acoustical Society of America (ASA) ; 1996
    In:  The Journal of the Acoustical Society of America Vol. 100, No. 4_Supplement ( 1996-10-01), p. 2645-2646
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 100, No. 4_Supplement ( 1996-10-01), p. 2645-2646
    Abstract: For the noninvasive diagnosis of heart disease based on the acoustic characteristics of the heart muscle, it is necessary transcutaneously to measure small velocity signals, including components with an amplitude of less than 100 μm/s, and to measure them continuously for periods of more than several heartbeats in a wide frequency range up to 1 kHz. Such measurement, however, has not been realized by any ultrasonic diagnostic method to date. By introducing the constraint least-squares approach, this paper proposes a new method for accurately tracking the movement of the heart wall based on both the phase and magnitude of the demodulated signal to determine the instantaneous position of the object so that the velocity of the moving object can be accurately estimated. By this method, a small velocity of the heart wall with small amplitudes less than 100 μm/s on the motion resulting from a heartbeat with large amplitude of 10 mm can be successfully detected, with sufficient reproducibility in the frequency range up to several hundred Hertz, continuously for periods of about ten heartbeats. The resultant small-velocity signal is analyzed not only in the time domain but also in the frequency domain. The new method offers potential for research in acoustical diagnosis of heart disease.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.417806
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 1996
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  • 9
    Online Resource
    Online Resource
    Basic study on angular dependence of ultrasonic scattering from wire phantom mimicking myocardium
    Acoustical Society of America (ASA) ; 2006
    In:  The Journal of the Acoustical Society of America Vol. 120, No. 5_Supplement ( 2006-11-01), p. 3361-3361
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 120, No. 5_Supplement ( 2006-11-01), p. 3361-3361
    Abstract: It is reported that the ultrasonic scattering from myocardium varies periodically during a cardiac cycle. One of the reasons is considered to be the change of the angle between the ultrasonic beam and the direction of myocardial fibers. Therefore, it is expected that ultrasonic scattering from myocardium quantitatively characterizes the condition of myocardium. To investigate the angle dependence of ultrasonic scattering in relation to the fiber direction, in this study, ultrasonic echoes from a wire phantom (thinner than a wavelength in diameter) that mimics myocardium were measured as a function of the insonification angle. Two ultrasonic transducers of 7 MHz were employed for transmitting and receiving ultrasonic pulses. Focal points of these transducers were set at the same point on the phantom. A custom-made experimental system can change the azimuth and elevation angles while keeping the focal points at the same point. Measured ultrasonic scattering showed a significant change depending on the azimuth angle. Such changes depending on the azimuth angle were decreased by increasing the elevation angle. These preliminary findings support the hypothesis that the change in the angle between the ultrasonic beam and myocardial fibers due to the heartbeat varies the ultrasonic scattering property.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.4781501
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2006
    detail.hit.zdb_id: 1461063-2
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  • 10
    Online Resource
    Online Resource
    Accurate ultrasonic measurement of two-dimensional displacement of heart wall motion for estimation of myocardial regional strain rate
    Acoustical Society of America (ASA) ; 2008
    In:  The Journal of the Acoustical Society of America Vol. 123, No. 5_Supplement ( 2008-05-01), p. 3787-3787
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 123, No. 5_Supplement ( 2008-05-01), p. 3787-3787
    Abstract: Methods for imaging of strain rate in the heart wall are useful for quantitative evaluation of regional heart function. We developed a method which can accurately measure the heart wall motion along an ultrasonic beam based on phase changes in rf echoes. However, there are some components in the wall motion which are not along each ultrasonic beam. Therefore, the measurement of motion in the direction perpendicular (lateral) to the beam has been required in addition to that in the axial direction, but some unsolved problems remain in estimation of lateral motion of the wall. In this study, two-dimensional displacement was estimated by 2D cross-correlation between rf echoes. Important parameters, the sizes of a region-of-interest and search region, which determine tracking accuracy, were adaptively optimized by referring to instantaneous wall velocities, in the respective cardiac phases. The correlation coefficient between the lateral displacement estimated by the 2D tracking with optimized parameters in longitudinal-axis view and axial displacement in apical view (corresponding to lateral displacement in longitudinal-axis view) separately and accurately estimated by the 1D phase-based method was 0.93. These results show possibility of this method for accurate measurement of two-dimensional heart motion to assess the regional myocardial strain rate.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.2935445
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2008
    detail.hit.zdb_id: 1461063-2
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