Single-Element Focused Ultrasound Transducer Method for Harmonic Motion Imaging

The harmonic motion imaging (HMI) technique for simultaneous monitoring and generation of ultrasound therapy using two separate focused ultrasound transducer elements was previously demonstrated. In this study, a new HMI technique is described that images tissue displacement induced by a harmonic radiation force using a single focused-ultrasound element. A wave propagation simulation model first indicated that, unlike in the two-beam configuration, the amplitude-modulated beam produced a stable focal zone for the applied harmonic radiation force. The AM beam thus offered the unique advantage of sustaining the application of the spatially-invariant radiation force. Experiments were performed on gelatin phantoms and ex vivo tissues. The radiation force was generated by a 4.68 MHz focused ultrasound (FUS) transducer using a 50 Hz amplitude-modulated wave. A 7.5 MHz pulse-echo transducer was used to acquire rf echoes during the application of the harmonic radiation force. Consecutive rf echoes were acquired with a pulse repetition frequency (PRF) of 6.5 kHz and 1D cross-correlation was performed to estimate the resulting axial tissue displacement. The HMI technique was shown capable of estimating stiffness-dependent displacement amplitudes. Finally, taking advantage of the real-time capability of the HMI technique, temperature-dependent measurements enabled monitoring of HIFU sonication in ex vivo tissues. The new HMI method may thus enable a highly-localized force and stiffness-dependent measurements as well as real-time and low-cost HIFU monitoring.

[1]  T. Krouskop,et al.  Phantom materials for elastography , 1997, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[2]  C. Damianou,et al.  Dependence of ultrasonic attenuation and absorption in dog soft tissues on temperature and thermal dose. , 1997, The Journal of the Acoustical Society of America.

[3]  J. Jensen,et al.  Calculation of pressure fields from arbitrarily shaped, apodized, and excited ultrasound transducers , 1992, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[4]  R. Sinkus,et al.  High-resolution tensor MR elastography for breast tumour detection. , 2000, Physics in medicine and biology.

[5]  Y. Fung,et al.  Biomechanics: Mechanical Properties of Living Tissues , 1981 .

[6]  J. Humphrey,et al.  Heat-induced changes in the mechanics of a collagenous tissue , 1997 .

[7]  K. Hynynen,et al.  Localized harmonic motion imaging: theory, simulations and experiments. , 2003, Ultrasound in medicine & biology.

[8]  J. Greenleaf,et al.  Selected methods for imaging elastic properties of biological tissues. , 2003, Annual review of biomedical engineering.

[9]  J D Humphrey,et al.  Heat-induced changes in the mechanics of a collagenous tissue: pseudoelastic behavior at 37 degrees C. , 1998, Journal of biomechanics.

[10]  M. Fink,et al.  Supersonic shear imaging: a new technique for soft tissue elasticity mapping , 2004, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[11]  F. S. Vinson,et al.  A pulsed Doppler ultrasonic system for making noninvasive measurements of the mechanical properties of soft tissue. , 1987, Journal of rehabilitation research and development.

[12]  Kullervo Hynynen,et al.  The temperature dependence of ultrasound-stimulated acoustic emission. , 2002, Ultrasound in medicine & biology.

[13]  S. Emelianov,et al.  Shear wave elasticity imaging: a new ultrasonic technology of medical diagnostics. , 1998, Ultrasound in medicine & biology.

[14]  J. Greenleaf,et al.  Ultrasound-stimulated vibro-acoustic spectrography. , 1998, Science.

[15]  T. Krouskop,et al.  Elastic Moduli of Breast and Prostate Tissues under Compression , 1998, Ultrasonic imaging.

[16]  J Bercoff,et al.  Monitoring Thermally-Induced Lesions with Supersonic Shear Imaging , 2004, Ultrasonic imaging.

[17]  M. Pernot,et al.  Single-element focused transducer method for harmonic motion imaging , 2005, IEEE Ultrasonics Symposium, 2005..

[18]  G. Trahey,et al.  On the feasibility of remote palpation using acoustic radiation force. , 2001, The Journal of the Acoustical Society of America.

[19]  S. Ueha,et al.  Tissue hardness measurement using the radiation force of focused ultrasound , 1990, IEEE Symposium on Ultrasonics.

[20]  K Hynynen,et al.  A focused ultrasound method for simultaneous diagnostic and therapeutic applications--a simulation study. , 2001, Physics in medicine and biology.

[21]  F S van Kleef,et al.  Determination of the number of cross‐links in a protein gel from its mechanical and swelling properties , 1978, Biopolymers.

[22]  A. Manduca,et al.  Magnetic resonance elastography by direct visualization of propagating acoustic strain waves. , 1995, Science.

[23]  J F Greenleaf,et al.  Probing the dynamics of tissue at low frequencies with the radiation force of ultrasound. , 2000, Physics in medicine and biology.

[24]  G E Trahey,et al.  The use of acoustic streaming in breast lesion diagnosis: a clinical study. , 1999, Ultrasound in medicine & biology.

[25]  J. Ophir,et al.  Elastography: A Quantitative Method for Imaging the Elasticity of Biological Tissues , 1991, Ultrasonic imaging.

[26]  S. Alam,et al.  Radiation-force technique to monitor lesions during ultrasonic therapy. , 2003, Ultrasound in medicine & biology.