Ultrasonic diffraction scanning of the thyroid

This paper reports the results of a preliminary clinical assessment of the value of ultrasonic diffraction analysis in identifying thyroid pathology. The trial involved 52 patients and nine normal volunteers and showed that, when used as a supplement to grey-scale B-scanning, diffraction analysis is capable of useful separation among several categories of pathology.     

Ultrasonic characterisation of diffuse liver disease—The relative importance of frequency content in the A-scan signal

Successful methods of ultrasonic characterisation of alcohol-induced diffuse liver disease using texture analysis (Lerski et al. 1979, 1980a, b) have studied the radiofrequency (RF) A-scan ultrasonic signal. In the present paper the Fourier spectra of such signals have been partitioned and a statistical analysis implemented to determine the diagnostic usefulness of certain frequency groups present in the signal. Although this method has not, of itself, been found to compare favourably with texture analysis it has shown that useful information is present in the high frequency portion of the frequency spectra. This information would not be available if the smoothed and demodulated A-scan signal were studied.     

先天性冠状动脉瘘—5例报告

本文报告5例先天性冠状动脉瘘。4 例术前进行了主动脉造影配合X线电影检查。2 例有二维超声检查结果。4例手术证实,1 例升主动脉造影证实。本文着重分析有关X线诊断问题。     

Doppler ultrasound in orifice flow. In vitro studies of the relationship between pressure difference and fluid velocity

The validity of an orifice equation (Torricelli's law) which expresses a simple relationship between the pressure difference across an orifice and the maximum fluid velocity in the orifice was tested in vitro. An aqueous suspension of barium sulfate particles with a polymer added to attain variations in viscosity, was forced through orifices which ranged in diameter from 0.4 to 4.7 mm. The pressure difference across the orifice was determined with a transducer and the maximum fluid velocity in the orifice was determined with Doppler ultrasound. Tests were performed at Reynolds numbers, fluid viscosities, and pressure differences that spanned the following ranges: 400-25,000, 1-5 cP, and 3-100 mmHg, respectively. At pressure differences larger than 3 mmHg and fluid viscosity 3 cP (approximate viscosity of in vivo blood), Torricelli's law was demonstrated to be valid for orifice diameters larger than 1.6 mm. The validity of the law was found to be relatively insensitive to variations in orifice length.     

A partial uterine perforation (type 2) by a copper-T IUD: sonographic diagnosis and management

The case reported in this paper demonstrates the difficulties in establishing the diagnosis of type 2 uterine perforation incident to the use of an IUD. A type 2 perforation is considered to have occurred when the IUD is entirely within the myometrium, no part of the IUD can be detected in the uterine cavity, and no part can be visually detected in the peritoneal cavity. The patient, a 28-year old gravida 3, para 2, had an IUD inserted 18 months prior to admittance, 7 weeks after her 2nd delivery. 1 year later she became pregnant. During a therapeutic abortion, the IUD string was removed without the device, which was considered to be outside and behind the uterus. Ultrasonography revealed that the IUD was inside the posterior uterine wall, parallel to the endometrial mucosal lining, with no connection to the uterine cavity. Other diagnostic methods used in this case included plain abdominal films, hysterography, and hysteroscopy; however, neither these methods nor uterine palpation suggested that there was an IUD in the uterus. The original diagnosis was later confirmed by intraoperative radiography, and the IUD was removed through a small incision on the posterior uterine wall. This case demonstrates the useful role of ultrasonography in the work-up of a woman with a missing IUD. It is suggested that ultrasonography be used following difficult IUD insertions or postpartum insertions, since most perforations occur in such cases. Partial and complete uterine perforation is considered more likely when the IUD is inserted during the 1st 3 months postpartum.     

The directional characteristics of some ultrasonic doppler blood-flow probes

A knowledge of the shape of the fields generated by Doppler ultrasonic probes is of particular importance in vessel imaging and in blood flow research. In this study the combined effects of the transmitting and receiving crystals of four types of commonly used Doppler probe have been calculated numerically using two different theoretical models, and the results compared with experimental measurements. The results show that there is a considerable variation in the fields produced by transducers of the same type, and that the correspondence between the theoretical and experimental results can be improved in most cases by using a model in which each crystal vibrates like a flexible plate rather than like a rigid piston. Theoretical iso-echo contours at various distances from the transducer face are presented for each of the four types of transducers studied.     

Microstreaming shear as a mechanism of cell death in Elodea leaves exposed to ultrasound

The hypothesis that ultrasonically induced membrane damage and cell death in Elodea leaves is caused by shear stress associated with microstreaming flow generated in the vicinity of oscillating gas-filled channels between the cells is investigated. Cell death thresholds as a function of frequency seem to follow a condition of constant shear stress, with minimum thresholds near the resonance frequency of a gas-filled channel. Theoretical estimates of the shear stress generated within the cells at the ultrasonic intensity of the cell death threshold are in order of magnitude agreement with measurements of the shear stress required for lysis of blood cells. Furthermore, the dependence of the cell death thresholds on exposure duration seems to correspond roughly with the dependence of critical shear stress for blood cells as a function of the duration of the stress. Membrane damage induced by microstreaming shear stress therefore appears to be a plausible mechanism of cell death in Elodea, and a valuable unifying concept for consideration of bioeffects of ultrasonic cavitation.     

The effects of ultrasound in vivo on mouse liver in contact with an aqueous coupling medium

Liver tissue of anaesthetised mice, exposed by dissection, has been treated while bathed in saline with therapeutic intensity levels of ultrasound for periods up to 2 min. Samples of tissue were taken on completion of the irradiations and prepared for light and electron microscope examination. Specimens irradiated with 0.8 MHz ultrasound contained patches of damaged tissue several hundred microns across at depths of up to 2 mm below the incident surface. In specimens treated with 1.5 MHz ultrasound, the surface few hundred microns of tissue was modified, and after 3 MHz irradiation no changes were found. When the abdominal wall covered the liver surface, no effects were observed at any frequency. The lowest intensity at which damage occurred was the same as that at which acoustic emission associated with cavitation could just be detected. The effects may be initiated by cavitation events occurring in the saline surrounding the liver.     

Evaluating carotid artery disease. The concordance between pulsed Doppler/spectrum analysis and angiography

The results of ultrasonic pulsed Doppler duplex scanning with spectral analysis and computer pattern recognition are compared with the results of contrast arteriography in patients screened for extracranial carotid artery disease. The intraangiographer variability (one radiologist reading the same films twice) and the interangiographer variability (two radiologists reading the same film independently) were also studied. To calculate degrees of agreement corrected for chance, the Kappa statistic was computed for all the evaluation methods employed.At the present time, the concordance between spectral analysis and cerebral contrast angiography reaches a Kappa value of 0.682±0.064. This level of agreement compares favorably with the interangiographer agreement level (K) = 0.568 ± 0.058 and the intraangiographer agreement (K) = 0.711 ± 0.054. The computer pattern recognition program predicted the degree of stenosis by angiography with an agreement of K = 0.721 ± 0.059. This concordance compares favorably to that observed when the radiologists are compared with themselves and is greater than that reached by two different radiologists. The continuous improvement in precision and accuracy of duplex scanning offers the promise of its usefulness in clinical and epidemiological studies.     

An unusual flat interface in orbital ultrasonic examinations

Systems of classifying orbital echograms have been developed to aid in increasing the diagnostic accuracy of the technique. An unusual flat interface was recorded in the retrobulbar region of three patients and in each case shown to be a horizontal plane separating two fluid regions. The dynamic behaviour of these regions was studied in one patient over a 30 min period and possible interpretations of the phenomenon discussed. In the other two patients the interface was restricted to one tumour lobule. The characteristic appearance described has been added to our diagnostic criteria and we expect it to add to the value of the technique in diagnosis of orbital pathology.