Showing papers in "Ultrasound in Medicine and Biology in 1974"

The production of blood cell stasis and endothelial damage in the blood vessels of chick embryos treated with ultrasound in a stationary wave field.

Abstract: Blood cell flow can be arrested in living tissue by exposing it to ultrasound in a stationary wave field. The cells form bands at half wavelength intervals in the blood vessels. The process is generally reversible, and during dissociation the hands assume a parabolic profile in vessels where flow is laminar. Under optimum conditions, in the chick embryo, the minimum intensity required for stasis is less than 0·5 Wcm −2 at 3 MHz with continuous irradiation. The threshold intensity varies with the type, size and orientation of the vessel, and with the heart rate. Electron microscopy reveals damage to some of the endothelial cells lining the embryonic vessels in which stasis has occurred. Methods of avoiding stasis are suggested and the mechanisms of stasis are discussed.

Ultrasonic atlas of normal brain of infant.

Abstract: In infants the skull does not form a barrier to ultrasound and a considerable amount of intracranial detail may be visualized by scanning over the skull. The shape of the lateral and third ventricle is clearly displayed and together with the characteristic appearance of the brain stem form the major displayed landmarks. A number of major nuclei and interfaces between white and grey matter are also visualized, in particular the head of the caudate nucleus and the thalamus. The ease and safety with which this information is obtained should make grey scale echographic examination of the infant brain a new major area of application for ultrasound.

A new ultrasonic imaging system using time delay spectrometry.

Abstract: A new method of forming a visual image by ultrasound is described. A shadowgraphic transmission image similar to an X-ray radiograph is produced by the application of a technique known as Time Delay Spectrometry. The system uses a repetitive frequency sweep with a linear relationship between frequency and time and the transmitting and receiving crystal are scanned in raster fashion about the subject. By electronic processing, an image may be built up which represents the energy transmitted through the specimen with a given time delay. An intensity modulated picture encompassing the full shades-of-gray capability of the recording system can be produced. A second type of image showing transmission time through the specimen may also be formed. Brightness changes in the displayed image in this case correspond to changes in the ultrasonic transmission time through the specimen.

Sonar--the story of an experiment.

Abstract: THERE are two main reasons for choosing a title such as this. Firstly it is necessary to put on record how this lengthy experiment came about. A combination of accident, coincidence and any amount of good luck seems to have driven us inexorably onwards. Secondly, it seems the most appropriate way in which I can publicly acknowledge the quite extraordinary variety of help which I have received from innumerable sources over the fifteen years about to be described. Looking back over this eventful time I recognize that I am no Michael Faraday, who, I believe, never left a day's experimental work at the Royal Society, close by Piccadilly, without carefully writing up all that he had done. In my own case it is only by looking through eight or nine thick files of correspondence that I have been able to piece together the story in retrospect. In the autumn of 1954 I arrived in Glasgow with only the residue of a Leverhulme Trust Research Grant from the Royal College of Obstetricians & Gynaecologists, a rudimentary knowledge of radar from my days in the Royal Air Force and a continuing childish interest in machines, electronic or otherwise--or what my wife would refer to as my "toys". While at Hammersmith Hospital the late Professor Ian Aird had introduced me to Dr. Wild from Minneapolis who was one of the early workers on ultrasound in the medical diagnostic field (Wild, 1950).

An esophageal Doppler probe for aortic flow velocity monitoring.

Abstract: An ultrasonic Doppler transducer suitable for intra-esophageal use in humans has been constructed, tested, and its function as a flow monitoring device assessed on a series of 15 unselected anaesthetized human subjects undergoing surgery. Doppler flow signals from the descending thoracic aorta have been obtained in all cases. Once correctly positioned, the probe can give continuous qualitative monitoring of pulsatile aortic blood flow velocity for extended periods. It is possible to observe flow waves in the descending thoracic aorta from the aortic arch distally for about 20 cm and observe the change from disturbed to laminar flow patterns over this length.

Evaluation of structure recognition with the multiscan echocardiograph. A cooperative study in 580 patients.

Abstract: Real time, two-dimensional, images of the heart can now be obtained with the multiscan ultrasound system recently introduced. To assess the clinical usefulness of this technique a cooperative study was carried out in four cardiac centers. This paper describes the experience with and the results in 580 patients with different ages and disorders. Since a unique feature of multiscan is the instantaneous display of cardiac geometry and anatomy, structure recognition was chosen as the most important parameter to analyze. Image quality or recognition levels for eight specific cardiac structures were documented. Results also include recognition levels for different age and disease groups and a comparison between the four centers. In addition, information was gathered on the general diagnostic capability of the multi-element system and the possibility of quantitation of dimensions. Aortic root, anterior mitral valve leaflet and left ventricular posterior wall were the structures most readily recognized. Excellent or good images were seen in two-thirds of all patients. Best visualization was obtained in young patients. A positive diagnosis could be made or confirmed in about one half of the patients with valvular, congenital or myocardial disease and in nearly all patients with pericardial effusion. As experience was gained, the diagnostic importance of the technique shifted from structure recognition towards analysis of left ventricular function. It is clear that the multiscan system does allow excellent orientation and yields quick, non-invasive information of pertinent clinical value. The method provides an immediate overall impression of the heart. It is foreseen that this technique in combination with existing time-motion recording methods will expand the use of echocardiography drastically.

Choice of standard target for medical pulse-echo equipment evaluation.

Abstract: Comparisons have been made between plane, spherical and cylindrical targets in relation to their suitability for quantitative evaluation of the performance of pulse-echo equipment for visualizing tissues. Using fifteen different transducers, with various frequencies and beam-shapes, spherical targets were found to relate much more closely (scatter of 12 dB) than did plane targets (40 dB) with the target strength measured in post mortem human liver.

Ultrasonic study of the refraction of patients with pseudophakos

Abstract: Ultrasonography and keratometry are used in the study of the refraction of the eye. The authors used the artificial implant lens after removal of the cataractous lens. The expected emmetropizing power of the implant lens can be calculated by a formula as well as the expected post-operative refraction which can also be calculated by second and third formulas. The authors compared the difference between the expected pre-operative and actual post-operative refraction. The factors giving this difference will be discussed. The expected emmetropizing power of the implant lens is not always the same as that of the iseikonizing power. A theoretical discussion of this problem is given.

Interaction of ultrasound and amniotic liquid.

Abstract: The ultrasonic properties (velocity at 2·81 and 5·04 MHz, absorption in the range 1–15 MHz and vibration potential at 200 kHz) of amniotic liquid have been investigated. The results indicate that at physiological pH the absorption is essentially due to the proteins found in amniotic liquid, its vibration potential to the sodium chloride contained in this fluid while the velocity appears to be determined both by the proteins and sodium chloride. In the acid range (pH ∼ 3) and alkaline range (pH ∼ 9·6), proton transfer processes involving a low molecular weight component of amniotic liquid, in addition to those involving the proteins, contribute to the absorption of ultrasound by amniotic liquid.

An automatic ultrasonic spherical section scanner.

Abstract: From a theoretical point of view it would seem advantageous with an ultrasonic scanner which from a selected site on the body surface could produce scanning pictures corresponding to spherical sections at varying depths and “parallel” to the surface. In the first place this applies to cases where it is desirable that all echoes recorded on the oscilloscope represent the same depth and thus the same attenuation—e.g. in searching for liver metastases. In the second place in cases where anatomical conditions restrict the possibilities of conventional ultrasonic scanning—e.g. in scanning of the liver and of the heart. A new ultrasonic scanner is described, allowing the scanning to be carried out according to the above mentioned principle. The scanning is performed automatically in a spiral motion. The thickness of the sections and their distance from the transducer can be chosen by means of a time gate.

Ultrasonic tomography of the heart.

Abstract: The report deals with 2 cases of heart tumors in which a commercial ultrasonic diagnostic equipment was used for tomography. In both cases we were successful in demonstrating the lesions. The visualization of subtle diagnostic details is ruled out by the rhythmical movements of the heart which cause blurring and superposition of signals.

Ultraschall in der strahlentherapie: Bei der bestrahlungsplanung und überwachung des therapieerfolges

Abstract: Zusammenfassung Die Echographie ist in der Strahlentherapie fur die Bestrahlungsplanung und die Kontrolle des Behandlungserfolges von groβem Wert. Die Ausdehnung eines Tumors und seine Lage zu den Nachbarorganen konnen direkt sichtbar gemacht werden. Durch Kombination des Fotos des B -Scans und des Isodosenplanes ist eine individuelle Bestrahlungsplanung moglich. Das wird an einigen Beispielen gezeigt: der praeoperativen Bestrahlung eines Wilms Tumors (Abb. 1), der Bestrahlung einer groβen aortalen Geschwulst, die 3 Stehfelder erfordert (Abb. 2), wahrend ein kleinerer aortaler Tumor fur die Bewegungsbestrahlung geeignet ist (Abb. 3). Die Kontrolle des Behandlungserfolges zeigt in Abb. 4 die Verkleinerung eines Tumors entsprechend der angewandten Bestrahlungsmethode. Die Strahlenresistenz eines Tumors kann bei manchen Tumorpositionen durch Ultraschall fruher als durch andere Methoden erfaβt werden. Das kann dem Radiotherapeuten helfen, seinen Behandlungsplan rechtzeitig umzustellen (Abb. 6)

Ultrasonic array scanning of the kidney

Abstract: An ultrasonic scanning system has been devised, utilizing an array of six plane transducers, each used as a separate transmitter-receiver. The transducers were arranged in a concave assembly so that their beams intersected at a point equidistant from each face. The array was mounted in a water-bath on a three-dimensional racking mechanism, so that it could be moved through a raster at various heights in the tank. In a fixed sequence, each individual transducer was excited, and the received ultrasonic echo amplitude information from the focus was selected by means of an electronic gate. The cartesian coordinates of the position of the array were also determined. Both sets of information were sampled, digitized and punched on to paper tape. A switching sequence was arranged so that eight successive characters on the paper tape represented the six echo amplitude data and the two positional data corresponding to a single point in the tank. The array was moved so that a two-dimensional matrix of points was interrogated. Experiments were performed to test the operating characteristics of the apparatus and to determine appropriate methods of signal processing and for the display of the information. It was found that the alignment of the ultrasonic beams was satisfactory and the data acquisition system was linear over a dynamic range approaching 40 dB. The apparatus was used to scan a simple model of wires and an isolated porcine kidney. Improved aximuthal resolution was achieved by combining the six amplitude data for each point. The product of these data seemed to be more useful than the sum. Contour mapping of received echo amplitude gave a satisfactorily wide dynamic range display. Possible future developments of the system are discussed.

A method of display dynamic range expansion using system gain wobbulation.

Abstract: The clinical relevance of the dynamic range of the display of two-dimensional ultrasonic scans is discussed. A method is described by which the effective dynamic range of the display may be expanded by relating the duration of the registration of the signal to the signal amplitude. This is achieved by wobbulation of the range of the swept gain control. The resulting improvement in the value of the display is illustrated by scans of a kidney made using a manually operated, direct contact scanner.

Choroidal detachment associated with scleritis—A case report with echograms

Abstract: The case presented is an 80-year-old woman who has suffered from scleritis in her right eye four times during the last 10 years. A week after the patient was taken ill for the fifth time with severe scleritis in her right eye, a dark and extensive, several millimeters high, circumferential protrusion was observed in the periphery of the fundus. An optic examination presented difficulties in differential diagnosis in relation to a melanoma, while a diascleral illumination brought out information against the possibility of a melanoma. At an ultrasonic examination the detachment itself reflected high echoes, as opposed to the low echoes obtained from the space under the detachment. The ultrasonic examination pointed to an exudative detachment of the choroid. After a week's treatment with mydriatics and steroids the choroidal detachment had disappeared completely.