Showing papers in "Ultrasonic Imaging in 1985"

TL;DR: In this article, B-mode echograms were simulated by employing the impulse response method in transmission and reception using a discrete scatterer tissue model, with and without attenuation.

TL;DR: In this paper, the center frequency of a narrowband, discrete-time random process, such as a reflected ultrasound signal, is estimated from the parameter values of a reduced, second-order autoregressive (AR) model.

TL;DR: A reconstruction algorithm is presented which possesses a simple scanning geometry and promises higher resolution than conventional transmission mode diffraction tomography algorithms, but the resolution will be shown to be limited by the bandwidth and physical size of the single plane wave transducer.

TL;DR: In this article, a theory for the diffracted fields of the transducer aperture (assumed to be a source of a Gaussian focussed beam), the interaction of these fields with the scattering sites, and the interaction with the transducers aperture with the back scattered fields is presented.

TL;DR: A novel tomographic system for imaging the nonlinear parameter (B/A) of biological objects is described, closely related to the detailed properties of tissue, and may well provide a new powerful tool for ultrasonic tissue characterization.

TL;DR: In this paper, the influence of specular reflectors on in vivo attenuation measurements is detailed. And the importance of the specular echo noise originating from two kinds of reflectors: plane-like and vessel-like reflectors is pointed out.

TL;DR: In this article, a generalized projection-slice theorem is derived for transmission fan beam diffraction tomography within the Born or Rytov approximations, based on the use of the so-called paraxial approximation which requires that the object being probed subtend a small angle relative to the source point and to the measurement plane.

TL;DR: Preliminary in-vitro images have been made using a computer-interfaced rectilinear scanner with a 1-inch diameter f/2.8 transducer, and they have good resolution and signal-to-noise ratio, and a short depth-of-field.

TL;DR: In this paper, global and local attenuation coefficient estimations were performed in a phantom using a pulse echo method based on the rate of decay of zero crossing density, where focussed and unfocussed 3.5 MHz transducers were used.

TL;DR: A model is presented for the radio-frequency image produced by a B-scan (pulse-echo) ultrasound imaging system using a phased-array transducer, which allows for dynamic focusing as well as an acoustic lens focusing the beam in the elevation plane.

TL;DR: An ultrasound contrast agent capable of increasing hepatic echogenicity would be useful for the detection of hepatic tumors and metastases and lipid emulsions do not appear to have potential as contrast agents for ultrasound examination of the liver.

TL;DR: In this article, a general model for attenuation in biological tissues is proposed, which consists of a series expansion of the attenuation coefficient, thereby covering the whole range of frequency dependencies from zero to four.

TL;DR: In this paper, a three-dimensional model for gray scale texture in ultrasound B-mode images has been extended to enable absolute quantitative predictions of echo signal levels and texture characteristics, and the quantitative aspects of the model are tested with a phantom in which the ultrasonic scattering properties as well as the attenuation coefficient and the speed of sound are known as functions of frequency.

TL;DR: It is shown theoretically and confirmed experimentally with ultrasound, that a gradient in scatterer density will return an echo which is partially spatially coherent (i.e. specular) and the surface of a random ensemble of uniform scatterers is shown to produce an echo from whose degree of coherence, the scattere density and cross section can be calculated.

TL;DR: Experimental work using a quantitative C-scan technique to measure in situ enhancement of hepatic backscatter resulting from the administration of gelatin microspheres to dogs has found reproducible enhancement on the order of 2 dB.

TL;DR: In this paper, a Hilbert transform approach was used to detect the instantaneous center frequency of reflected ultrasonic pulses and digitized ultrasonic waveforms from tissue phantoms, and the observed frequency modulation of ultrasonic signals has important implications for tissue characterization techniques, including the measurement of attenuation by the determination of the ultrasonic center frequency.

TL;DR: Acquisition and analysis of tissue texture data using polar coordinates should allow a more definitive identification of abnormal tissue.

TL;DR: An improved scan conversion algorithm for ultrasound compound scanning is proposed, which greatly simplifies implementation of a real-time digital scan converter (DSC) for spatial compounding of ultrasound images.

TL;DR: The possibility of applying the prior inverse filtering method to improve medical ultrasound images and the diffraction effects of the transducer and the observed scatterer are examined experimentally as well as theoretically.

TL;DR: In this article, the design of the system, and the use of thin metal reflectors, reduce the reverberations between and within their component parts to an acceptable level, and losses in the system are minimized.

TL;DR: In this paper, a method for restoring both the amplitude and bandwidth of the signal and an implemention of this method is proposed, which consists of two main parts: a device for estimating the attenuation and a time-variable circuit.

TL;DR: In this article, Vaknine and Lorenz discuss the merits of lateral deconvolution of demodulated B-scans and apply it to the echoes arising from inhomogeneous structures such as soft tissue.