Measurement of shear wave absorption with correction of the diffraction effect for viscoelasticity characterization of soft tissues

Abstract

An ultrasonic method for measuring shear wave (SW) propagation properties in soft tissues was investigated for viscoelasticity characterization. A continuous SW was induced into a specimen by an external vibration source. The displacements within the specimen due to the SW propagation were measured by a speckle-echo tracking method using a conventional B-mode scan of focused ultrasound. SW velocity and absorption coefficient of the specimen were retrieved from the measured SW waveforms with the compensation of the SW diffraction. The effect of positioning error of the ultrasound probe on the diffraction calculation was studied by numerical simulations. It was shown that the estimation error of the SW absorption could be reduced by selecting an appropriate SW measurement region where the diffraction estimation precision is less sensitive to the positioning error of the probe. Finally, the shear elasticity and viscosity of a soft tissue mimicking phantom were estimated.

Introduction to rheometry for researchers of ultrasonics

“…Knowledge about the rheological properties of bio systems is also important for the application of ultrasonic investigation to the medical field. [29][30][31][32][33] One problem is that the measurement of biohazardous material is difficult because the mechanical probe of the viscometer should be in direct contact with the sample. The pollution from/to the sample is inevitable, and the cost of cleaning the measurement apparatus is not negligible.…”

Extension of remote distance of electromagnetically spinning viscometer

“…Ultrasonic absorption is determined by the viscosity of a propagation medium. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] The viscosity can be classified into two types based on the deformation mode of the medium: the shear and volume viscosities. Many types of ultrasonic relaxation in aqueous solutions of ionic salts occur through the modification of temperature, which is the direct contribution of adiabatic volume compression.…”