Showing papers in "Ultrasound in Medicine and Biology in 1988"
TL;DR: Measurements performed up to 20 min after treatment showed that the cell was able to reduce this calcium influx, indicating that the membrane did not suffer irreparable damage as a result of the ultrasound exposure.
Abstract: The effect of therapeutic ultrasound on calcium uptake by embryonic chick 3T3 fibroblasts has been studied using calcium-45 radiotracer techniques. Cells were treated while suspended in culture medium at 36 degrees C at intensities from 0.25 W/cm2 SPPA to 1.5 W/cm2 SPPA (1 MHz, pulsed 2 ms on:8 ms off) and for exposure times from 1 min to 20 min. Ultrasound treatment was found to increase calcium uptake for SPPA intensities from 0.5 to 1.0 W/cm2 SPPA, with a maximum increase of 18% after a 5 min exposure. Calcium uptake also increased with increasing exposure time. Measurements performed up to 20 min after treatment showed that the cell was able to reduce this calcium influx, indicating that the membrane did not suffer irreparable damage as a result of the ultrasound exposure.
253 citations
TL;DR: The effect of shock waves on normal canine kidneys was examined in three groups of dogs whose right kidneys were exposed to 500, 1500, or 3000 shock waves and haemorrhages were shown to originate from interlobular and arcuate veins.
Abstract: The effect of shock waves on normal canine kidneys was examined in three groups of dogs whose right kidneys were exposed to 500, 1500, or 3000 shock waves. Autopsy was performed 24–30 h later. The kidneys were enlarged with haemorrhages in the outer and inner renal capsule and intraparenchymally. Macroscopically intraparenchymal haemorrhages were restricted to the high pressure field of the shock wave and consisted of haematomas up to 18 mm diameter (most frequently 6 mm or less) and diffuse haemorrhages. Histologically, haemorrhages were shown to originate from interlobular and arcuate veins. Venous thrombosis, tubular dilatation, and diffuse interstitial haemorrhage occurred in the same area. The number of haematomas was larger, and diffuse haemorrhages were more extended after the application of 1500 and 3000 than after 500 shock waves. No difference was seen between 1500 and 3000 shock waves.
235 citations
TL;DR: The age dependence of the blood flow velocities of the middle, anterior, and posterior cerebral arteries measured by the transcranial Doppler method is discussed and compared with the velocity values in the internal carotid artery.
Abstract: The age dependence of the blood flow velocities of the middle, anterior, and posterior cerebral arteries measured by the transcranial Doppler method is discussed and compared with the velocity values in the internal carotid artery. A number of 535 patients without neurological deficits but with a previous neurological event were examined. Flow velocities decrease in all examined vessels with increasing age. This is in accordance with cerebral blood flow measurements by Xenon inhalation techniques. The reasons of the decrease and its consequences on the vasospasm in patients suffering from subarachnoidal hemorrhage are discussed.
145 citations
TL;DR: Two groups of dogs whose right kidneys were exposed to 3000 shock waves generated with 20 kV and 40 nF in a Dornier HM II lithotripter show that kidney damage is dependent on the rate of shock wave administration.
Abstract: The effect of shock waves on normal canine kidneys was examined in two groups of dogs whose right kidneys were exposed to 3000 shock waves generated with 20 kV and 40 nF in a Dornier HM II lithotripter The groups differed only in the rate of shock wave administration which was 100 and 1 per second, respectively Autopsy was performed 24 to 30 h later Macroscopically and histologically, significantly more haemorrhages occurred in the kidney parenchyma if shock waves were administered at a rate of 100 waves per second Haemorrhages were diffuse, the outer medulla was most heavily affected The results show that kidney damage is dependent on the rate of shock wave administration They argue against a direct shock wave effect and favor cavitation as the mechanism of shock wave damage although thermal effects cannot be excluded
135 citations
TL;DR: Results indicate that both the AR(Yule-Walker) and ARMA(singular value decomposition) models of orders (8) and (4,4), respectively, show good agreement with the theoretical spectrum, and yield estimates with variances considerably less than the Fast Fourier Transform (FFT).
Abstract: Various alternative spectral estimation methods are examined and compared in order to assess their possible application for real-time analysis of Doppler ultrasound arterial signals. Specifically, five general frequency domain models are examined, including the periodogram, the general autoregressive moving average (ARMA) model which has the autoregressive (AR) and moving average (MA) models as special cases, and Capon's maximum likelihood spectral model. A simulated stationary Doppler signal with a known theoretical spectrum was used as the reference test sequence, and white noise was added to enable various signal/noise conditions to be created. The performance of each method representative of each spectral model was assessed using both qualitative and quantitative schemes that convey information related to the bias and variance of the spectral estimates. Three integrated performance indices were implemented for quantitative analysis. The relative computational complexity for each algorithm was also investigated. Our results indicate that both the AR(Yule-Walker) and ARMA(singular value decomposition) models of orders (8) and (4, 4), respectively, show good agreement with the theoretical spectrum, and yield estimates with variances considerably less than the Fast Fourier Transform (FFT). Preliminary results obtained with these methods using a clinical, non-stationary Doppler signal supports these observations.
132 citations
TL;DR: A theoretical analysis of soft-tissue ultrasonic scattering has been used to formulate specific results describing spectral parameters for tissue characterization and results from a clinical data base are shown to agree well with analytical results for each spectral parameter.
Abstract: A theoretical analysis of soft-tissue ultrasonic scattering has been used to formulate specific results describing spectral parameters for tissue characterization. Results are applicable to clinical liver examinations. Three spectral parameters are mathematically expressed in terms of acoustic attenuation and the effective sizes, concentrations, and relative acoustic impedances of tissue scatterers. Results from a clinical data base are shown to agree well with analytical results for each spectral parameter. Agreement is found for: spectral shapes; effects of attenuation; and correlations between parameters. Images of three spectral parameters are presented and their gray-scale features are evaluated with reference to analytical results.
129 citations
TL;DR: Over the first three days of life there was a significant increase in blood flow velocity in each of the vessels, and a significant fall in RI and RAP.
Abstract: Cerebral artery Doppler ultrasound recordings, and intra-arterial pressure measurements have been made from 27 very low birth weight infants during the first week of life. These data were used to calculate Pourcelot's resistance index (RI), mean blood flow velocity, and resistance-area product (RAP), in both the anterior and middle cerebral arteries. There was a good degree of correlation between recordings from different sites on the same occasion, but absolute values were site dependent. Over the first three days of life there was a significant increase in blood flow velocity in each of the vessels, and a significant fall in RI and RAP.
113 citations
TL;DR: The accuracy of the echo-Doppler method using the criteria of the AI was 95%, the sensitivity was 100%, and the specificity was 93%.
Abstract: The accuracy of the diagnosis of renal artery stenosis using noninvasive echo-Doppler velocimetry was compared with that of angiography in 40 renal arteries. The duplex-Doppler signals were detected through the muscle of the back (the translumbar approach). Renal artery stenosis was diagnosed by three objectively defined Doppler parameters, the acceleration index (AI), the acceleration time (AT), and the acceleration time ratio (ATR). The normal range obtained on 11 control subjects was defined as AI greater than or equal to 3.78, AT less than or equal to 0.07 s, and ATR less than or equal to 1.35. High technological success (98%) was obtained using the translumbar approach. In comparison with angiography (cases of significant stenosis), the accuracy of the echo-Doppler method using the criteria of the AI was 95%, the sensitivity was 100%, and the specificity was 93%. This noninvasive method may be one of the most accurate screening methods for diagnosing significant renal artery stenosis.
102 citations
TL;DR: Since the stiffer behavior of the common carotid artery in borderline hypertensives is associated with relatively slight changes in blood pressure, the question can be raised whether the alterations in arterial wall properties are really a result of the elevated arterial blood pressure; these alterations might develop independent of the blood pressure elevation.
Abstract: The vessel wall properties of the common carotid artery were studied noninvasively in normotensive and borderline hypertensive male volunteers of various ages with the use of a multi-gate pulsed Doppler system. In the younger age group (20–35 y) both distensibility and cross-sectional compliance were significantly less in the borderline hypertensive group. In the older borderline hypertensive subjects (50–69 y) distensibility (p < 0.05) and cross-sectional compliance (p = 0.06) were also less than in the control subjects. The reduced distensibility and cross-sectional compliance likely result from a decrease in arterial wall elasticity because the relative increase in common carotid artery diameter during systole is diminished in borderline hypertensives, despite the fact that their pulse pressure is similar to or higher than that in control subjects. The less pronounced differences in vessel wall properties between borderline hypertensive and normotensive volunteers in the older age group may be a consequence of the changes in these properties with age, partly masking the alterations due to borderline hypertension. Since the stiffer behavior of the common carotid artery in borderline hypertensives is associated with relatively slight changes in blood pressure, the question can be raised whether the alterations in arterial wall properties are really a result of the elevated arterial blood pressure; these alterations might develop independent of the blood pressure elevation.
97 citations
TL;DR: Overall, it was found that the modified threshold method and the new hybrid method have the best performance over a wide range of signal and noise conditions; however, D'Alessio's method also performs well for low SNR's.
Abstract: The performance of four methods for digitally estimating the maximum frequency waveform from the Doppler ultrasound spectrum, are described. The methods investigated are: a percentile method, D'Alessio's threshold crossing method [D'Alessio T. (1985) "Objective" algorithm for maximum frequency estimation in Doppler spectral analysers. Med. Biol. Engng and Comput. 23, 63-68.], a modified threshold crossing method, and a new hybrid algorithm. Evaluations of the variance and bias were performed using stationary simulated continuous wave (CW) Doppler signals of different bandwidths and signal/noise ratios (SNR) of 9 and 17 dB. Furthermore, a simulated nonstationary Doppler signal, similar to that from a normal internal carotid artery, was also used to compare the various methods. Overall, it was found that the modified threshold method and the new hybrid method have the best performance over a wide range of signal and noise hybrid method have the best performance over a wide range of signal and noise conditions; however, D'Alessio's method also performs well for low SNR's.
96 citations
TL;DR: In this article, the authors consider spectral estimation methods as a problem of fitting an assumed model to the Doppler signal, where the models described assume that the signal is stationary and a short enough time window interval can be chosen over which the signal can be considered stationary.
Abstract: When compared to the classical Discrete Fourier Transform (DFT) or Fast Fourier Transform (FFT) approach, modern estimation methods offer the potential for achieving significant improvements in estimating the power density spectrum of Doppler ultrasound signals. Such improvements, for example, might enable minor flow disturbances to be detected, thereby improving the sensitivity in arterial disease assessment. Specifically, reduction in the variance and bias can be achieved, and this may enable disturbed flow to be detected in a more sensitive manner. The approach taken here, is to consider spectral estimation methods as a problem of fitting an assumed model to the Doppler signal. The models described assume that the signal is stationary. Since the Doppler signal is generally nonstationary, it is assumed that a short enough time window interval can be chosen over which the signal can be considered stationary. We shall review the various methods and when appropriate, relate them to the nature of the Doppler signal.
TL;DR: A significant correlation was found between high values of attenuation and abnormal liver function tests, and high attenuation is also found with ingestion of alcohol, chemotherapeutic agents, and steroids, all of which may affect liver composition.
Abstract: Ultrasonic attenuation coefficients of liver have been derived from echoes received by a modified commercial B-scan imaging instrument Values have been measured from selected regions within liver scans of 59 individuals, of which 15 cases were presumed normal (based on medical histories), and the remainder were involved with diffuse liver disease such as alcoholic cirrhosis, chemotherapy toxicity, chronic hepatitis, and liver metastases Medical histories on most individuals include the results of serum liver function enzymes, conventional B-scan examinations, and exposure to drugs and alcohol The results of CT abdominal scans (N = 13) and/or liver biopsy (N = 12) were also available The results show that normal attenuation values for human liver are 0054 +/- 0009 Np/cm-MHz (047 dB/cm-MHz) with a frequency dependence of fn, where n = 105 +/- 025, in agreement with in vitro studies of mammalian liver In diffuse liver disease, no relationship was found between the attenuation coefficient and the results of CT or conventional ultrasonic examination A trend towards higher attenuation with increased fibrosis and fat, as graded from liver biopsies, was noted, but the results were generally not statistically significant However, a significant correlation was found between high values of attenuation and abnormal liver function tests High attenuation is also found with ingestion of alcohol, chemotherapeutic agents, and steroids, all of which may affect liver composition
TL;DR: A clear quantitative separation was demonstrated between the kinetic response of three classes of tissue: normal liver in volunteers, metastatic deposits in liver of cancer patients, and histologically normal liver regions in the same patients.
Abstract: An analysis is made of the kinetics of human liver parenchyma in response to mechanical impulses arising in the heart and aorta, and the results are applied to predicting the time course of the correlation between two time-separated A-scans derived from various regions of the liver. Such predictions are found to correspond well with data derived clinically, both from volunteers and from patients with liver metastases, using a commercial, real-time sector scanner. On the basis of Fourier spectral features of the clinically derived correlation patterns, a clear quantitative separation was demonstrated between the kinetic response of three classes of tissue: normal liver in volunteers, metastatic deposits in liver of cancer patients, and histologically normal liver regions in the same patients.
TL;DR: Epidemiologic studies and surveys and widespread clinical usage over 25 years have yielded no evidence of any adverse effect from diagnostic ultrasound, but the inability to find convincing proof of an effect does not preclude it happening.
Abstract: Epidemiologic studies and surveys and widespread clinical usage over 25 years have yielded no evidence of any adverse effect from diagnostic ultrasound. Nonetheless, the inability to find convincing proof of an effect, either from epidemiology or from physicians' experience, does not preclude the possibility of it happening. Statistical reasoning shows that even with large population studies, it is difficult to identify a small increase in the rate of a commonly occurring event. Subtle effects, long-term delayed effects, and certain genetic effects, could easily escape detection.
TL;DR: C Cavitation was consistently produced when TA was exposed in a soft vinyl chamber and only when the chamber was being rotated about an axis which was perpendicular to the US beam, suggesting the use of TA as a quantitative indicator of transient cavitation should be of value to the study of ultrasonic biological effects and dosimetry.
Abstract: A simple and sensitive method is described for measuring the number of hydroxyl radicals (.OH) produced in aqueous solution by high intensity ultrasound (US). The method is based on the conversion of nonfluorescent terephthalic acid (TA) to highly fluorescent hydroxyterephthalate (HTA). The spectrofluorimeter is calibrated by use of a TA solution which has been exposed to a reference dose of cobalt-60. This allows fluorescence readings produced by ultrasound to be read directly in equivalent centiGrays (cGy). The limit of detection for OH is about 1.3 X 10(-9) M (equivalent to an exposure of about 0.5 cGy of cobalt-60). The threshold for transient cavitation (TC) in an air-saturated aqueous solution was found at 0.7 watts per cm2. Cavitation was consistently produced when TA was exposed in a soft vinyl chamber and only when the chamber was being rotated about an axis which was perpendicular to the US beam. The use of TA as a quantitative indicator of transient cavitation should be of value to the study of ultrasonic biological effects and dosimetry.
TL;DR: The results indicate that for an f/1 transducer with a focal depth of 50 mm the upper limit of maximum useful aperture size has not been reached and the measured resolution improvement in tissue is approximately 2/3 of that obtained in water.
Abstract: Ultrasound focussing through human tissue of thicknesses varying from 10 mm to 35 mm has been measured for two transducers with diameters 50 mm and 19 mm both focussed at 50 mm (f/1 and f/2.6, respectively). Comparisons are made between the two-way focal depth beam patterns obtained in water and those obtained after passage through tissue to study the degrading effects of frequency-dependent attenuation and inhomogeneities, and their dependence on aperture size. The effects of frequency-dependent attenuation is to broaden the beam and shorten the focal distance. Inhomogeneities mainly increase the sidelobe levels and cause deviations from the central beam axis. A direct comparison of the beam patterns of the two transducers after passage through the same tissue samples shows that the resolution is improved by using the larger aperture. The use of the larger transducer in the in vitro measurements on three human liver specimens demonstrated an average improvement in the −6 dB beamwidth, over the smaller transducer, of 42% (standard deviation ± 3%). The average improvement in the in vivo measurements on ten female breasts was 34% (standard deviation ±5%). The measured improvement in water was 52%. Therefore, the measured resolution improvement in tissue is approximately 2 3 of that obtained in water. The results indicate that for an f/1 transducer with a focal depth of 50 mm the upper limit of maximum useful aperture size has not been reached.
TL;DR: At high cell concentrations as present in whole blood, the authors observed no cell death, whereas below 5 X 10(7) cells/ml most of the granulocytes, stimulated lymphocytes and Reh cells were damaged, and the concentration threshold below which cells were damage seemed not to depend on the size of the cells, rather on the concentration of particles in the suspension.
Abstract: Cell membrane damage by ultrasound was studied in human nucleated cells in vitro at various concentrations. Suspensions of human blood cells, cells of a human leukemic cell line (Reh) and mixtures of nucleated cells with erythrocytes were exposed to continuous ultrasound of 782 kHz at a SPTA intensity of 15 W/cm2. The surviving nucleated cells without membrane damage were counted on the basis of exclusion of ethidium bromide using a flow cytometer. At high cell concentrations as present in whole blood, we observed no cell death, whereas below 5 X 10(7) cells/ml most of the granulocytes, stimulated lymphocytes and Reh cells were damaged. The concentration threshold below which cells were damaged seemed not to depend on the size of the cells, rather on the concentration of particles in the suspension.
TL;DR: It was found that the presence of the dicrotic notch in the uterine artery time-velocity waveform is the result of wave reflection and that a persistent notch past 20 weeks' gestation may be indicative of an abnormally high placental bed resistance.
Abstract: An electrical analogue model of an artery that terminates into a vascular bed is presented. The model consists of an uniform transmission line that represents the artery and a load impedance that represents the vascular bed. The transmission line parameters are based on a well-established first-order approximation of the Navier-Stokes equations for fluid flow in distensible tubes. The model can be used to predict the incident and reflected components of both the arterial pressure and flow waveforms. In addition, it can predict the vessel diameter change and the mean blood velocity waveforms. In this study, the model was applied to the uterine artery so that the characteristics of the utero-placental circulation can be related to Doppler ultrasound recordings. It was found that the presence of the dicrotic notch in the uterine artery time-velocity waveform is the result of wave reflection and that a persistent notch past 20 weeks' gestation may be indicative of an abnormally high placental bed resistance. It is shown that the simulation results are consistent with the known physiological data and the clinically recorded uterine Doppler waveforms.
TL;DR: The results may explain some of the conflicting literature in this area, and suggest that attenuation may in principle be used for screening for liver disease, but not for differentiation between fatty and fibrotic conditions.
Abstract: The attenuation coefficient in two groups ( n 1 = 70; n 2 = 59) of pathologically graded in vitro human liver specimens was measured over a frequency range from 1.25-8.0 MHz and fitted to a power law model. The slopes of the power law curves at 5 MHz were correlated with pathological scores for fat in Group I, which consisted of normal and fatty livers (no fibrosis); they were also correlated with the pathological score for fibrosis in Group II, which consisted of normal and fibrotic livers (no intracellular fat). Significant ( p −1 MHz −1 (fat grade) −1 behavior (mean ± s.d.), while the fibrotic liver group exhibited approximately a 0.11 ± 0.01 dB cm −1 MHz −1 (fibrosis grade) −1 behavior. These results may explain some of the conflicting literature in this area, and suggest that attenuation may in principle be used for screening for liver disease, but not for differentiation between fatty and fibrotic conditions.
TL;DR: The long term aim is to create an environment suitable for the use of multivariate statistical methods systematically to evaluate ultrasound interpretive criteria and diagnostic performance in relation to factors such as scanning instrumentation and other diagnostic techniques.
Abstract: Semi-quantitative diagnostic features were extracted by a visual analysis of the echographic images of selected cases of breast disease and the results stored in a computer database. The long term aim is to create an environment suitable for the use of multivariate statistical methods systematically to evaluate ultrasound interpretive criteria and diagnostic performance in relation to factors such as scanning instrumentation and other diagnostic techniques. Eventually it is hoped that it will be possible to generate a system for computer assisted diagnosis and training. The results of this pilot study serve to demonstrate the feasibility of the approach and a univariate analysis is used to provide a preliminary ranking of diagnostic features. Features found to be particularly valuable for distinguishing benign from malignant solid lesions were the regularity and definition of the edge of the tumour, the mobility of the tumour and measures of echo heterogeneity within and posterior to the tumour mass.
TL;DR: A means of correcting for the depth dependence of co-occurrence features derived from ultrasonic images of the in vivo human placenta was derived and these features found to correlate with a subjective assessment of the texture.
Abstract: A means of correcting for the depth dependence of co-occurrence features derived from ultrasonic images of the in vivo human placenta was derived. The corrected features were used to characterise the texture of the images. The features were found to correlate with a subjective assessment of the texture (p
TL;DR: An ultrasonic descaler working at kHz frequencies is used in dentistry to remove attached deposits from the teeth andTherapeutic ultrasound has been used to treat a variety of dentally related ailments, and ultrasonic cleaning baths are used to clean both dental instruments and materials.
Abstract: An ultrasonic descaler working at kHz frequencies is used in dentistry to remove attached deposits from the teeth. Such devices offer many advantages over conventional hand instruments by reducing both the work and time involved in the clinical descaling process. Although it is a recognised clinical instrument, there has been little attempt to standardise its acoustic power output. A parameter which may characterise adequately the acoustic emission from these instruments is the displacement amplitude of the probe tip. Modification of the ultrasonic descaler generator has led to the further use of the instrument in other dental areas. Diagnostic applications of MHz ultrasound is limited by the structure and arrangement of the dental tissues. Therapeutic ultrasound has been used to treat a variety of dentally related ailments, and ultrasonic cleaning baths are used to clean both dental instruments and materials.
TL;DR: There is a high probability of distinguishing malignant from benign processes by means of the mentioned criteria and the rating value of each individual appraisal criterion is shown.
Abstract: Use of breast sonography for clarification of pathological alterations in the breast is continuously increasing. It is known that cystic processes can be distinguished from solid processes with this method. The question of, to what extent, a prognosis of pathological relevance of such processes can be made, is of increased interest. This prognosis of pathological relevance is related to interpretative criteria which are not uniformly defined all over the world and which are also differently applied.
The present investigation (evaluation of 755 sonographic focal findings) shows the rating value of each individual appraisal criterion and provides information on the certainty with which malignant and benign lesions in the breast can be distinguished.
All interpretative criteria specified have a statistical significant difference (p < 0,0001, 0,0044) in their rating pattern in malignant and benign processes. The criterion with the highest value is the wall contour.
In principle, every sonographic focal finding should be examined with regard to its wall contour, the acoustic attitude of posterior wall, the internal echo pattern and the internal echogenicity. In the dynamic part of the investigation, alterations in the form and structure of the lesion must be registered.
In our opinion there is a high probability of distinguishing malignant from benign processes by means of the mentioned criteria.
TL;DR: In the one hundred patients examined with both procedures, there was an improvement in the accuracy of diagnosing breast disease due to the reduction in the number of false positive and negative reports compared to the accuracy in the imaging examination alone.
Abstract: Two separate series of patients were investigated to determine the improvement in diagnostic accuracy obtained by combining the results of ultrasonic imaging and vascularity assessment for the detection and diagnosis of breast disease. In the first series, ninety-five patients were examined with a hand-held Doppler probe to verify that abnormal flow could be detected in the presence of breast disease. To determine the clinical efficacy of combining the two examination procedures, a second series of patients was examined with the Doppler transducers incorporated into the water-bath scanner so that the sample volume could be accurately positioned into specific regions previously imaged. In the one hundred patients examined with both procedures, there was an improvement in the accuracy of diagnosing breast disease due to the reduction in the number of false positive and negative reports compared to the accuracy of the imaging examination alone.
TL;DR: Using the transcranial Doppler technique, the carbondioxide reactivity of the blood flow velocity in the human basilar artery was investigated in healthy volunteers and a normal value should be quite helpful for the bed-side evaluation of an altered CO2 response in the patients with cerebrovascular disease.
Abstract: Using the transcranial Doppler technique, the carbondioxide reactivity of the blood flow velocity in the human basilar artery (BA) was investigated in healthy volunteers for comparison with that in the middle cerebral artery (MCA). An exponential curve with an exponent of 0.044 mmHg-1 was found to be a good fit to the BA data and 0.040 mmHg-1 to the MCA data, respectively. While the response of both arteries showed a good correlation to the end-tidal carbondioxide partial pressure (PETCO2), there was no significant difference observed between the carbondioxide (CO2) reactivity of each artery. In both arteries, the end-diastolic flow velocity decreased significantly with the reduction of PETCO2, which may represent the increasing resistance of cerebral microvasculature in hypocapnia. Because of the reliability and noninvasiveness of this method, this normal value should be quite helpful for the bed-side evaluation of an altered CO2 response in the patients with cerebrovascular disease.
TL;DR: The first in vitro results of this study illustrate that integration of catheter tip imaging and spark erosion is possible and may be used as a guidance for these new techniques to recanalize obstructed arteries during catheterization.
Abstract: Presently several new methods are being developed to recanalize obstructed arteries during catheterization. Intra-arterial high frequency ultrasonic imaging may be used as a guidance for these new techniques. Spark erosion is a new obstruction removal technology. Experiments have shown that this method can be applied in a selective way. An ultrasonic intra-arterial imaging system allows for the proper indication of the spark erosion catheter relative to the obstruction. The first in vitro results of this study illustrate that integration of catheter tip imaging and spark erosion is possible.
TL;DR: Modulated ultrasound is shown to offer an improved diagnosis of hearing diseases and confirms the previous observation that amplitude-modulated ultrasound may excite not only the acoustic receptors but also the acoustic nerve fibres.
Abstract: Focused ultrasound with a frequency of 2.5 MHz and amplitude-modulated in the range of audiometric frequencies (125–8000 Hz) was employed to examine 50 normal hearing persons and in complex diagnostics of over 500 patients suffering from sensorineural deafness, otosclerosis, chronic otitis media, and acoustic neurinoma. Typical diagnostic signs of these diseases were revealed. Modulated ultrasound is shown to offer an improved diagnosis of hearing diseases. The results confirm the previous observation that amplitude-modulated ultrasound may excite not only the acoustic receptors but also the acoustic nerve fibres. Possible mechanisms of the stimulating effect of focused modulated ultrasound are discussed.
TL;DR: An experiment using phantoms shows that US can detect and identify even 100-500 mu-sized tiny objects in an "ideal" low echoic area similar to microcalcifications within breast carcinomas.
Abstract: The author succeeded in detecting microcalcifications within breast carcinomas, by ultrasound(US) imaging, at the beginning of 1982, and published the results of his clinical and experimental researches at the Third International Congress on the Ultrasonic Examination of the Breast held on June 10 – 12, 1983, in Tokyo, Japan) After that, more detailed clinical evidence was acquired and new experiments, using breast phantoms, were carried out. This paper introduces an experiment using phantoms which shows that US can detect and identify even 100–500μ-sized tiny objects in an “ideal” low echoic area similar to microcalcifications within breast carcinomas. Actual clinical evidence is also presented.