Determination of the Nonlinearity Parameter B/A for Water and m-Xylene

Abstract

The rate at which harmonics are developed during the propagation of an initially sinusoidal ultrasonic wave of finite amplitude depends on the nonlinearity of the compressibility of the medium. Thus, determinations of the harmonics as a function of propagation distance may be used to determine the parameter B/A (describing nonlinearity). A method which circumvents the effects of absorption in the medium is developed and used to determine the parameter B/A for water and m-xylene. This method utilizes optical determinations of the second harmonic component of a distorted 3.0 Mc ultrasonic wave at various distances and initial pressure amplitudes. The second harmonic was isolated by use of a calibrated acoustic filter plate. The values obtained for the nonlinearity parameter are B/A = 6.2±0.6 for water and B/A = 9.6±1 for m-xylene.

Determination of the nonlinear parameter by propagating and modeling finite amplitude plane waves

“…The finite amplitude method consists in measuring the amplitude of the second harmonic of a distorted plane monochromatic wave. 10 In the phase comparison method, 11 B / A is determined from the time shift of tone bursts due to adiabatic variation of the hydrostatic pressure. Sarvazyan 12 developed a specific method for aqueous solutions and Everbach 13 another one for immiscible mixtures.…”

Qualitative and quantitative effects of harmonic echocardiographic imaging on endocardial edge definition and side-lobe artifacts

“…Although the harmonic components are weak, the harmonics are sufficiently strong that tuning the ultrasound receiver to the second harmonic frequency, amplifying the returning signal, and filtering out nonharmonic frequencies preferentially displays the tissue effect within the image. 17 We report in this study the clinical impact of a major technologic advancement in cardiac ultrasound, harmonic imaging, which dramatically improves endocardial border delineation. Not only is the improvement in endocardial definition statistically significant, but it is clinically significant.With harmonic imaging of the technically difficult-to-image Results are for pixel intensity (0 to 255 scale), except for wall-to-cavity ratio.…”

“…The energy at the second harmonic frequency increases in intensity in direct proportion to the transmission distance and the square of the applied acoustic pressure. 17 As the ultrasound pulse travels, it quickly builds energy at the harmonic frequency. Much of the echocardiographic artifacts are due to reverberations and scattering at the chest wall, as well as to aberrant propagation through tissue, including beam-width and side-lobe artifacts.…”

Finite Amplitude Measurements of the Nonlinear Parameter B/A for Liquid Mixtures Spanning a Range Relevant to Tissue Harmonic Mode

“…We would therefore expect the ratio of experimentally measured quantities on the left hand side of eqn 2to yield the same constant value at each position along the axis of the propagating plane wave. This relationship is equivalent to forms used in experimental studies published by Adler and Hiedemann (1962) and Law et. al.…”

“…An alternative approach is to perform a relative measurement by comparing the results obtained with the material under test to those obtained with a reference material whose nonlinearity parameter is known. By assuming a value for the nonlinearity parameter β in water, several researchers have successfully measured the value of β in a range of fluids (Adler and Hiedemann, 1962;Dong et al, 1999;Germain et al, 1989;Gong et al, 1984;Gong et al, 1989;Law et al, 1985Law et al, ,1981Saito et al, 2005;Shklovskaya-Kordi, 1963), biological tissues (Gong et al, 1984;Gong et al, 1989;Law et al, 1985Law et al, , 1981, tissue mimicking phantoms (Dong et al, 1999) and ultrasonic contrast agents (Wu and Tong, 1998).…”