The nonstationary strain filter in elastography: Part II. Lateral and elevational decorrelation.

The nonstationary evolution of the strain filter due to lateral and elevational motion of the tissue scatterers across the ultrasound beam is analyzed for the 1-D cross-correlation-based strain estimator. The effective correlation coefficient that includes the contributions due to lateral and elevational signal decorrelation is used to derate the upper bound of the signal-to-noise ratio in the elastogram (SNRe) predicted by the ideal strain filter. In the case of an elastically homogeneous target, if the transducer is on the axis of symmetry of such target in the elevational direction, the motion of the scatterers out the imaging plane is minimized. In addition, the ultrasound beam along the elevational direction is broader, allowing scatterers to stay longer within the beam during tissue compression. Under these conditions, lateral signal decorrelation becomes the primary contributor to the nonstationary behavior of the strain filter. Both the elastographic SNRe and the dynamic range are reduced, with an increase in lateral decorrelation. Finite element simulations and phantom experiments are presented in this paper to corroborate the theoretical strain filter. The nonstationary behavior of the strain filter is reduced by confining the tissue in the lateral direction (minimizing motion of tissue scatterers), thereby improving the quality of the elastogram.

[1]  B. Garra,et al.  Elastography: Ultrasonic imaging of tissue strain and elastic modulus in vivo , 1996 .

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

[3]  F. Kallel,et al.  Elastography: A systems approach , 1997, Int. J. Imaging Syst. Technol..

[4]  J. Ophir,et al.  Three-dimensional tissue motion and its effect on image noise in elastography , 1997, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[5]  M. Bilgen,et al.  Deformation models and correlation analysis in elastography. , 1996, The Journal of the Acoustical Society of America.

[6]  I Céspedes,et al.  Fundamental mechanical limitations on the visualization of elasticity contrast in elastography. , 1995, Ultrasound in medicine & biology.

[7]  Jonathan Ophir,et al.  Performance Optimization in Elastography: Multicompression with Temporal Stretching , 1996 .

[8]  R. F. Wagner,et al.  Statistics of Speckle in Ultrasound B-Scans , 1983, IEEE Transactions on Sonics and Ultrasonics.

[9]  J Ophir,et al.  Performance optimization in elastography: multicompression with temporal stretching. , 1996, Ultrasonic imaging.

[10]  K J Parker,et al.  Tissue response to mechanical vibrations for "sonoelasticity imaging". , 1990, Ultrasound in medicine & biology.

[11]  Michel Bertrand,et al.  Ultrasonic texture motion analysis: theory and simulation , 1995, IEEE Trans. Medical Imaging.

[12]  T. Varghese,et al.  A theoretical framework for performance characterization of elastography: the strain filter , 1997, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[13]  Mehmet Bilgen.  Multiresolution strain filter in elastography. , 1998 .

[14]  Faouzi Kallel,et al.  Tissue elasticity reconstruction using linear perturbation method , 1996, IEEE Trans. Medical Imaging.

[15]  M. O’Donnell,et al.  Internal displacement and strain imaging using ultrasonic speckle tracking , 1994, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[16]  P. Carson,et al.  Magnetic-resonance imaging techniques for detection of elasticity variation. , 1995, Medical physics.

[17]  J. Ophir,et al.  Methods for estimation of subsample time delays of digitized echo signals. , 1995, Ultrasonic imaging.

[18]  Kevin J. Parker,et al.  Techniques for elastic imaging: a review , 1996 .

[19]  B. Garra,et al.  Elastography of breast lesions: initial clinical results. , 1997, Radiology.

[20]  J Ophir,et al.  Elastographic Dynamic Range Expansion Using Variable Applied Strains , 1997, Ultrasonic imaging.

[21]  Michael F. Insana,et al.  Signal processing strategies in acoustic elastography , 1996, 1996 IEEE Ultrasonics Symposium. Proceedings.

[22]  A. Sarvazyan.  Shear acoustic properties of soft biological tissues in medical diagnostics , 1993 .

[23]  J. Ophir,et al.  Methods for Estimation of Subsample Time Delays of Digitized Echo Signals , 1995 .

[24]  Elastic properties imaging by periodical displacement NMR measurements (EPMRI) , 1994, 1994 Proceedings of IEEE Ultrasonics Symposium.

[25]  I Céspedes,et al.  Noise reduction in elastograms using temporal stretching with multicompression averaging. , 1996, Ultrasound in medicine & biology.

[26]  J. Ophir,et al.  Reduction of signal decorrelation from mechanical compression of tissues by temporal stretching: applications to elastography. , 1997, Ultrasound in medicine & biology.

[27]  T. Varghese,et al.  Enhancement of echo-signal correlation in elastography using temporal stretching , 1997, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[28]  J Ophir,et al.  Fundamental limitations on the contrast-transfer efficiency in elastography: an analytic study. , 1996, Ultrasound in medicine & biology.

[29]  C. Sumi,et al.  Estimation of shear modulus distribution in soft tissue from strain distribution , 1995, IEEE Transactions on Biomedical Engineering.

[30]  S Y Emelianov,et al.  Elasticity imaging for early detection of renal pathology. , 1995, Ultrasound in medicine & biology.

[31]  J Ophir,et al.  The nonstationary strain filter in elastography: Part I. Frequency dependent attenuation. , 1997, Ultrasound in medicine & biology.

[32]  D B Plewes,et al.  Visualizing tissue compliance with MR imaging , 1995, Journal of magnetic resonance imaging : JMRI.

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

[34]  J. Ophir,et al.  The combined effect of signal decorrelation and random noise on the variance of time delay estimation , 1997, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[35]  L.N. Bohs,et al.  A novel method for angle independent ultrasonic imaging of blood flow and tissue motion , 1991, IEEE Transactions on Biomedical Engineering.

[36]  M. Bilgen,et al.  Error analysis in acoustic elastography. I. Displacement estimation. , 1997, The Journal of the Acoustical Society of America.

[37]  G. P. Beaumont,et al.  Methods of Estimation , 2015 .

[38]  M. Bilgen,et al.  Error analysis in acoustic elastography. II. Strain estimation and SNR analysis. , 1997, The Journal of the Acoustical Society of America.

[39]  A.R. Skovoroda,et al.  Tissue elasticity reconstruction based on ultrasonic displacement and strain images , 1995, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[40]  G. Carter.  Coherence and time delay estimation , 1987, Proceedings of the IEEE.