Spatially variant regularization for tissue strain measurement and shear modulus reconstruction

PurposeRegarding the regularization of the displacement vector measurement and shear modulus reconstruction, we propose to properly set the regularization parameters, i.e., to use spatially variant regularization parameters at each point in the region of interest, because the measurement accuracies of the displacements and strains vary spatially.MethodAs the measurement accuracies of the strains can be evaluated using the correlation coefficient when using the cross-spectrum phase gradient method, preliminarily the regularization parameters were set proportional to the reciprocal of a power of the correlation coefficient.Results and conclusionSuch a regularization scheme realizes the spatially uniform stabilities of the strain measurement and shear modulus reconstruction. The effectiveness of this method was verified by showing the regularized results of the axial strain measurement and of one-dimensional (1-D) shear modulus reconstruction obtained in vivo from a human liver carcinoma (that was treated by interstitial microwave coagulation therapy) as well as by a 1-D shear modulus reconstruction obtained using an agar phantom.

[1]  E. Weinstein,et al.  Delay and Doppler estimation by time-space partition of the array data , 1983 .

[2]  A. Weiss,et al.  Fundamental limitations in passive time delay estimation--Part I: Narrow-band systems , 1983 .

[3]  Tomy Varghese,et al.  Elastographic Imaging of Thermal Lesions in Liver In-Vivo Using Diaphragmatic Stimuli , 2004, Ultrasonic imaging.

[4]  L. Wilson,et al.  Ultrasonic measurement of small displacements and deformations of tissue. , 1982, Ultrasonic imaging.

[5]  S. Yagi.  Local displacement analysis of inhomogeneous soft tissue by spatial correlation of rf echo signals , 1988 .

[6]  Kiyoshi Nakayama,et al.  Phantom Experiment on Estimation of Shear Modulus Distribution in Soft Tissue from Ultrasonic Measurement of Displacement Vector Field , 1995 .

[7]  C. Sumi,et al.  Fine elasticity imaging utilizing the iterative RF-echo phase matching method , 1999, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[8]  Frédérique Frouin,et al.  Ultrasound elastography based on multiscale estimations of regularized displacement fields , 2004, IEEE Transactions on Medical Imaging.

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

[10]  J Ophir,et al.  Estimating the elastographic signal-to-noise ratio using correlation coefficients. , 2002, Ultrasound in medicine & biology.

[11]  Evaluation of variances of ultrasonically measured strain tensor components , 2007 .

[12]  Estimation of shear modulus distribution in soft tissue from strain measurement , 1993 .

[13]  S. Salcudean,et al.  Identifying the mechanical properties of tissue by ultrasound strain imaging. , 2006, Ultrasound in medicine & biology.

[14]  Hiroshi Kanai,et al.  Feasibility of shear modulus imaging technique for monitoring the effectiveness of the interstitial rf electromagnetic wave thermal therapy , 2001, SPIE BiOS.

[15]  Jonathan Ophir,et al.  Comparative evaluation of strain-based and model-based modulus elastography. , 2005, Ultrasound in medicine & biology.

[16]  C. Sumi.  Our recent strain-measurement-based shear modulus reconstruction , 2005, IEEE Ultrasonics Symposium, 2005..

[17]  B. R. Hunt,et al.  The Application of Constrained Least Squares Estimation to Image Restoration by Digital Computer , 1973, IEEE Transactions on Computers.

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

[19]  Makoto Yamakawa,et al.  Strain Estimation Using the Extended Combined Autocorrelation Method , 2001 .

[20]  J. Felmlee,et al.  Assessment of thermal tissue ablation with MR elastography , 2001, Magnetic resonance in medicine.

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

[22]  O. Nalcioglu,et al.  Constrained Iterative Reconstruction by the Conjugate Gradient Method , 1985, IEEE Transactions on Medical Imaging.

[23]  C. Sumi,et al.  Usefulness of ultrasonic strain measurement- based shear modulus reconstruction for diagnosis and thermal treatment , 2005, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

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

[25]  Chikayoshi Sumi,et al.  A robust numerical solution to reconstruct a globally relative shear modulus distribution from strain measurements , 1998, IEEE Transactions on Medical Imaging.

[26]  J Ophir,et al.  The feasibility of elastographic visualization of HIFU-induced thermal lesions in soft tissues. Image-guided high-intensity focused ultrasound. , 1999, Ultrasound in medicine & biology.

[27]  J. Bamber,et al.  Quantitative elasticity imaging: what can and cannot be inferred from strain images. , 2002, Physics in medicine and biology.

[28]  M. Doyley,et al.  Elastographic imaging of thermally ablated tissue in vitro , 1999, 1999 IEEE Ultrasonics Symposium. Proceedings. International Symposium (Cat. No.99CH37027).

[29]  Stabilization of tissue displacement and strain measurement method utilizing the phase of the ultrasonic rf-echo cross-spectrum , 2001 .

[30]  Yanning Zhu,et al.  A Modified Block Matching Method for Real-Time Freehand Strain Imaging , 2002, Ultrasonic imaging.

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

[32]  T. Varghese,et al.  Direct strain estimation in elastography using spectral cross-correlation. , 2000, Ultrasound in medicine & biology.

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

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

[35]  Jonathan Ophir,et al.  Noise Performance and Signal-to-Noise Ratio of Shear Strain Elastograms , 2005, Ultrasonic imaging.

[36]  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.

[37]  In vivo elastographic investigation of ethanol-induced hepatic lesions. , 2005, Ultrasound in medicine & biology.