Two-Point Frequency Shift Method for Shear Wave Attenuation Measurement

Point shear wave elastography method for assessing liver stiffness.

AIM To estimate the validity of the point shear-wave elastography method by evaluating its reproducibility and accuracy for assessing liver stiffness. METHODS This was a single-center, cross-sectional study. Consecutive patients with chronic viral hepatitis scheduled for liver biopsy (LB) (Group 1) and healthy volunteers (Group 2) were studied. In each subject 10 consecutive point shear-wave ...

Seismic attenuation tomography using the frequency shift method

We present a method for estimating seismic attenuation based on frequency shift data. In most natural materials, seismic attenuation increases with frequency. The high-frequency components of the seismic signal are attenuated more rapidly than the low-frequency components as waves propagate. As a result, the centroid of the signal’s spectrum experiences a downshift during propagation. Under the...

A new method for attenuation coefficient measurement in the liver: comparison with the spectral shift central frequency method.

OBJECTIVE To assess the feasibility of a new method of measuring the attenuation coefficient in the liver, which offers less variability of results than the conventional method. METHODS The attenuation coefficient was evaluated on the basis of the following equation with sound field correction: [log(M0 (z)) - tau(z)]. In our system, the attenuation coefficient was also evaluated by the spectr...

Analytical and Experimental Comparisons Between the Frequency-Modulated-Frequency-Shift Measurement and the Pulsed-Wave-Time-Shift Measurement Doppler Systems

In previous publications, a new echo-ranging Doppler system based on transmission of repetitive coherent frequency-modulated ͑FM͒ sinusoids in two different implementations was presented. One of these implementations, the frequency-modulated–frequency-shift measurement ͑FM–fsm͒ Doppler system is, in this paper, compared with its pulsed-wave counterpart, the pulsed-wave– time-shift measurement ͑PW–ts...

A numerical calculation method for frequency-shift of a plasma wave using wave digital filters