Showing papers in "Ultrasonic Imaging in 1991"

TL;DR: Initial results of several phantom and excised animal tissue experiments are reported which demonstrate the ability of this technique to quantitatively image strain and elastic modulus distributions with good resolution, sensitivity and with diminished speckle.

TL;DR: An algorithm to suppress low frequency Doppler signals effectively and efficiently, while all the data points within the segment considered contribute equally to the average Dopplers frequency computed is presented.

TL;DR: The results indicate that the second-order statistics determine the performance of the correlation-based algorithm and can be used to predict theperformance of other angle-independent flow detection techniques.

TL;DR: The results indicate that phase aberrations significantly degrade breast image quality for typical transducer frequencies and sizes.

TL;DR: The proposed homogeneous region growing mean filter technique effectively smoothes ultrasonic speckle and completely suppresses isolated impulsive noise over the entire texture in addition to preserving the edge information.

TL;DR: A newly developed correlation interpolation method to measure the regional velocity of moving tissue is evaluated in an experimental setup and the accuracy of the calculated angular velocity was found to be better for large angles between the two lines of observation than for small angles.

TL;DR: Results of measurements of ultrasound speed and absorption coefficients in breast tissues at 37 C are reported and analyzed in attempts to identify a set of ultrasound parameters capable of discriminating normal, benign, and malignant tissues.

TL;DR: In this paper, the authors considered data from a Doppler sample volume as a two-dimensional function of depth and time, and the properties of its 2DFFT were discussed.

TL;DR: Theoretical derivations of the first order statistical properties of SNR images are given for the case of intensity coding of the original images for low number densities and for the limit case of fully developed speckle.

TL;DR: A preselection of the independent ultrasound parameters that could be used in a discriminant analysis to perform a differentiation of intraocular melanomas was enabled and the sensitivity and specificity of differentiating spindle cell type from mixed-epitheloid meleanomas were 92 and 89 percent, respectively.

TL;DR: In this paper, an experimental study in diffraction tomography whose main goal was to determine experimentally the performance of the filtered backpropagation algorithm in ultrasound tomography is described.

TL;DR: A method has been developed for mapping density and ultrasonic speed in 1 mm thick slices of soft tissue with a resolution of about 1 mm, and has been applied to breast tissues of three patients including tumors and surrounding tissue.

TL;DR: In this article, the effects of various modifications of the matrix, i.e., the relative scattering strength, the orientation and the position uncertainty of the scatterers, on the statistical parameters were systematically investigated.

TL;DR: In this article, an extension to the TACT method is presented for the estimation of sound speed with a single transducer to any depth. But the authors do not consider the effect of transaxial compression.

TL;DR: Apparatus is described for measurement of sound speed and ultrasound attenuation coefficients by the substitution technique in the frequency range 3 to 8 MHz, yielding sound speeds accurate to +/- 6.7 m/s, for samples 10 mm thick.

TL;DR: Two new methods for estimating frequency-dependent attenuation are proposed which improve the compromise between the estimation variance of this parameter and the analyzed tissue volume and are compared to those of other already existing estimators.

TL;DR: In this article, a back-and-forth propagation algorithm is used to reconstruct tomograms of various layers to be imaged, and then an iterative algorithm eliminates these ambiguities and resolves layers that are only two wavelengths apart.

TL;DR: The extension of a method for imaging acoustic backscatter coefficients that allows for greater spatial resolution in the resulting images is reported by using a broad-band excitation pulse and short-duration time gates in the analysis.