Showing papers in "Ultrasonic Imaging in 1990"

TL;DR: An alternative, relative processing method for determining the backscatter coefficient and the attenuation coefficient is presented here, which involves comparison of echo data from a sample with data recorded from a reference phantom whose back scatter and attenuation coefficients are known.

TL;DR: Local variations in attenuation, the center frequency and bandwidth of the transducer, and the distribution of scatterer sizes greatly influence the accuracy of estimates and the appearance of the image, thus demonstrating the importance of these factors in parametric image interpretation.

TL;DR: Correlation interpolation is introduced as a method to determine the displacement of moving biological tissue on the basis of a sequence of ultrasonic echo signals, while the ratio of the number of samples in depth and time is irrelevant.

TL;DR: To reduce hardware requirements and the bandwidth required for digital processings, this paper describes an efficient method to generate the sampling clocks for dynamic focusing and steering and some modified bandwidth sampling techniques to reduce the sampling rate for signal digitization.

TL;DR: Comparing the two reference methods for ultrasound tissue characterization, re-classification based on chemical/morphometrical analysis resulted in a significant increase in diagnostic accuracy.

TL;DR: It is demonstrated by multiple linear regression analysis that the “mean grey level” of the ultrasound-B-scan image depends not only on total lipid content but even more on the histomorphological fat deposit distribution.

TL;DR: The simulation study adequately explains the macrostructural geometric distortion and loss of resolution in the straight-ray image due to refraction effects that are unaccounted for.

TL;DR: This paper deals with the estimation of the slope of attenuation in human breast tissue with a short time Fourier analysis and shows a weak correlation with the type of the breast: normal or pathological.

TL;DR: It is shown theoretically and experimentally that accurate speed of sound estimations can be made in overlying and underlying tissue mimicking layers.

TL;DR: A pilot study involving 53 specimens of excised human female breast tissue was performed to provide preliminary estimates of the acoustic shear wave speed of sound and linear attenuation coefficient associated with high risk for development of invasive breast cancer.

TL;DR: The maximum likelihood, minimum variance, unbiased estimator for wideband measurement of backscatter is developed together with its performance and has strong implications for system design for measuring cyclic myocardial back scatter.

TL;DR: Methods to derive the phase-derivative (PD) signal from the complex envelope and the preenvelope of the echo signal are described and first and second order characteristics of the PD images are calculated for the conditions employed in simulations and experiments and are quantitatively compared to the values obtained from these.

TL;DR: It is shown that totally incoherent transducers completely remove diffraction effects, which might be used in attenuation estimation, in which case, correction for diffraction is no longer required, in order to obtain unbiased estimates.

TL;DR: The scanning laser acoustic microscope provides a relatively simple means by which speed of sound data can be collected from biological specimens by employing a phase detection circuit and phase-contour lines can be superimposed on acoustic micrographs and digitized for direct speed ofSound calculations.

TL;DR: In this article, a method based on a Kalman filter was proposed to assess the transducer parameters by measurement of the spatial sound field pressure amplitude distribution in various planes for different emission frequencies.

TL;DR: A new statistical method which minimizes the second-order moment of an object that indicates the variance and randomness in a statistical structure is proposed and successfully applied to ultrasound attenuation CT using a sponge phantom.

TL;DR: The phase, relative to the arterial pressure, of cyclically varying integrated backscatter from canine myocardium was measured at normal and reduced coronary blood flow levels and was found to become more randomized with decreasing flow.