Ultrasonic characterization of abdominal tissues via digital analysis of backscattered waveforms.

Abstract

Ultrasonic waveforms backscattered from normal and abnormal livers and spleens were recorded in vivo with the aid of a high-speed data acquisition system. Frequency-domain analysis of the digitized waveforms was employed to derive values for mean spacing of ultrasonic scatterers in tissue. Amplitude-domain analysis yielded measures of mean amplitude and variance, an indication of the distribution of amplitude values. Studies indicated that cirrhotic liver is characterized by a higher mean amplitude, a broader amplitude distribution, and a larger mean scatterer spacing than normal liver. Amplitude- and frequency-domain statistics for livers with other diffuse disease processes or tumor, as well for abnormal spleens. also differed from those of normal tissues. These data give information which may not be evident from B-mode sonograms, and which appears to be related to histological features.

Statistical properties of radio-frequency and envelope-detected signals with applications to medical ultrasound

“…This has been a summary outline of the simple model that has been evolving for ultrasound rf analysis over the past 5-10 years. Evidence for the applicability of the model has been offerred by Lizzi et al, 5 Feleppa et al, 7 Sommer et al, 20 Fellingham and Sommer, 21 and Waag, 6 among others. It has been speculated that difficulties in applying the model are due to isolated large scatterers with the structure discussed in class (3) above, namely, the intermediate-size domain in the order of a few wavelengths.…”

“…The scattering site removes energy from the plane wave and reradiates spherical waves whose amplitude is a function of frequency and the size of the scatterer. For the weak-scattering condition 13 the Born approximation is valid, 16 and the amplitude Φ b (2k) for scattering waves of wave number k in the backward direction is (20) where Γ κ (2k) is the FT in the variable 2k of the distribution of fluctuation in compressibility γ κ . The variable 2k is the difference in wave vector between incoming and backscattered waves.…”

“…A number of investigators have reported observing such structure in abdominal organ tissue. [20][21][22][23] The pulse in diagnostic ultrasound is usually about three wavelengths long-about 1-2 mm. This means that these regular structures are partially resolved and therefore produce a line spectrum corresponding to this spacing (scaled by c/2) that will be directly superimposed upon the measured diffusescatterer rf power spectrum.…”

Trial of a quantitative method for evaluating hemangioma of the liver and hepatocellular carcinoma using a radio-frequency signal

“…Various reports have been published concerning this approach, including attempts to utilize various parameters and RF signals obtained from B-mode ultrasound images, and to utilize artificial neural networks for the analysis of such data. [26][27][28][29][30][31] Based on the knowledge that when the living body is considered as a group of scatterers the RF signals from soft tissue (e.g., liver tumor) follow the K distribution, the present study was undertaken to perform a quantitative evaluation of hepatic hemangioma and HCC using two parameters, i.e., f (the mean square of the RF signal amplitude) and a (the number of effective scatterers). 15,16 In this study, f was significantly higher for hepatic hemangioma than for HCC, while a did not differ between hemangioma and HCC.…”

A Review of Wavelet Denoising in MRI and Ultrasound Brain Imaging

“…-For an experienced radiologist, speckle noise, which is in the medical literature also referred to as "texture" [39], may present useful diagnostic information [49,50]. The desired degree of speckle smoothing should ideally depend on the expert's knowledge and on the application at hand, like enhancement for visual inspection or preprocessing for automatic segmentation.…”