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PubMedDate not supplied

Digital x-ray imaging: the basics.

This article defines the terminology of digital imaging and presents an introduction to several modalities, with emphasis on digital video subtraction angiography. Topics discussed include special imaging considerations and problems, operating modes, and equipment configuration.

Analog-Digital Conversion↗
PubMed1984

[Digital subtraction ventriculography in determining global and regional left ventricular parameters compared to left catheterization cardiography].

Since May 1982 we studied more than 150 patients with heart diseases by means of digital angiography, out of them 46 patients with a history of transmural myocardial infarction were selected. Urografin 76, 30 ml, was administered at a flow rate of 18 ml/s by means of a catheter in the superior vena cava during digital subtraction ventriculography. Results were compared with conventional contrast ventriculograms. The correlation coefficient was r = 0.93 (p less than 0.001) for determination of ejection fraction with both methods. The data in individual cases suggest that DSV is more sensitive than conventional contrast ventriculography in determination of severely reduced ejection fractions. The methods are practically identical in qualitative evaluation of disorders of regional wall motion in the anterolateral region, while DSV is more sensitive than conventional ventriculography in evaluating the apical region. Sensitivity was 85.7% when the two methods were compared in evaluation of the inferior region of the left ventricle. Both methods are identical in demonstration of severely deformed ventricles. Digital subtraction ventriculography may replace conventional contrast ventriculography in some of the situations discussed above.

Analog-Digital Conversion↗
PubMed1984

[Present status of digital subtraction angiography].

The present state of development of digital subtraction angiography can be characterised by the fact that, according to the results obtained so far, it can be most useful as a diagnostic method, depending on the clinical problems involved and on the condition of the patient, taking into consideration any possible history of patient allergy and the state of his cardiac and renal functions; if there are no contra-indications, the requisite contrast medium can be applied intravenously or intra-arterially. This method can also be used as a complement to conventional large-format angiography to obtain additional information; in other cases, it may not supply information in sufficient detail, thus requiring subsequent large-format angiography. Diagnostic safety of this method is more than 95% in all the essential indications, such as diagnosis of extracranial cerebrovascular disturbances of blood flow, detection of aneurysms of the aorta, evaluation of postoperative and post-treatment conditions in the vascular system, as well as renovascular hypertension. However, an essential prerequisite is the appropriate use of technical aids fitted to the equipment used for examination. Other essential requirements are the best possible positioning of the patient and his ability to cooperate.

Analog-Digital Conversion↗
PubMed1984

[Digital subtraction angiography with dynamic color function images].

The authors present for the first time the principles and initial results of a laboratory pilot plant with which parametric colour images can be produced in real time. These images are digital function images of the type originally made widely known by Höhne et al. The colour function images can be produced during conventional digital subtraction angiography (DSA) practically as a sideline, that is to say, with a minimum of time and effort, as a parallel product. Despite the fact that the course of the functional processes can be visualised dynamically, the only feature required is the storage capacity of a single digital TV screen image. Of course, the colour function image is not a substitute for exact quantitative evaluations. However, it does furnish a rapid survey of haemodynamic processes for a multitude of patients in routine diagnosis.

Analog-Digital Conversion↗
PubMed1984

[Advances in diagnosis and their significance for radiological practice].

Many changes have taken place in x-ray diagnosis from the early introductory days of tomography and the introduction and development of the image intensifier. Ultrasound marked a big step forward. There are now about 12 000 ultrasound units in the FRG. In general practice, ultrasound is mainly used for screening examinations of the abdominal organs, whereas in hospitals special examinations are of great importance, such as neonatal skull, thyroid gland, mammary gland, scrotal sonography, and the valuation of blunt traumas. In nuclear medicine, an important advance was the application of spect in the diagnosis and localisation of disturbances of regional myocardial perfusion in coronary heart disease. In the last years CT has revolutionised radiology. In the FRG, the number of CT units, and all kinds of CT investigations in hospitals and in general practice, have been increasing rapidly. In 1983, there were 361 CT scanners in the FRG. The interdisciplinary character of radiology emerges especially in those areas which are known as interventional radiology. The most important methods are percutaneous transluminal angioplasty, percutaneous transhepatic cholangiography, puncture and drainage of abscesses, extraction of intraluminal foreign bodies, as well as therapeutical occlusion of vessels. Digital subtraction angiography is a new imaging method which is now available at all major departments in Western Germany. The method is well established by transvenous contrast medium injection for examination of the carotids, the renal arteries, the aorta, and the larger vessels of the extremities. Another new imaging method, magnetic resonance, has produced excitement in medical imaging.(ABSTRACT TRUNCATED AT 250 WORDS)

Analog-Digital Conversion↗
PubMed1984

[Arterial digital subtraction angiography for visualizing hemodialysis shunts].

Intraarterial application of contrast medium in digital video subtraction angiography was used to visualize chronic haemodialysis arteriovenous shunts. Patient compliance could be enhanced by the use of small volumes of non ionic contrast medium (3 ml/inj.), and the use off thin needles. The diagnostic reliability was excellent for all 25 examinations.

Adult↗
PubMed1980

Octant vectorcardiography.

Potentials recorded from the heart by the FRANK lead system are expressed in figures by means of analog-to-digital convertors. An elementary table is thus obtained, in which positive and negative numbers of X, Y, Z of eight possible combinations are called octants and have been numbered successively. The sequence of octants during a single depolarization is individual, but characteristic for a given group. Patients after myocardial infarction were examined and classified in this manner. Further more, peak amplitudes were assessed as the second parameter, i.e. the maxima of positive and negative potentials of X, Y, Z. The octants and peaks produce a network of a higher order to that in examined patients and may serve for the diagnostics of heart infarction. The method is intended for qualitative evaluation of coronary insufficiency, for which it provides novel information. It introduces computer techniques into electrocardiography.

Analog-Digital Conversion↗
PubMedDate not supplied

[Fundamental bases of digital information processing in nuclear cardiology (III)].

This article describes the transformation of the gamma-camera images into digital form. The incidence of a gamma photon on the detector, produces two voltage pulses, which are proportional to the coordinates of the incidence points, and a digital pulse, indicative of the occurrence of the event. The coordinate pulses passes through a analog-digital converter, that is activated by the pulse. The result is the appearance of a digital number at the out-put of the converter, which is proportional to the voltage at its in-put. This number, is stored on the accumulation memory of the system, either on a list mode or on a matrix mode. Static images can be stored on a single matrix. Dynamic data can be stored on a series of matrixes, each representing a different period of acquisition. It is also possible to capture information on a series of matrixes syncronized with the electrocardiogram of the patient. In this instance, each matrix represents a distinct period of the cardiac cycle. Data stored on the memory, can be used to process and display images and quantitative histograms on a video screen. In order to do that, it is necessary to translate the digital data on the memory to voltage levels, and to transform these on light levels on the screen. This, is achieved through a digital analog converter. The reading of the digital memory must be syncronic with the electronic scanning of the video screen.

Analog-Digital Conversion↗
PubMedDate not supplied

[Unit complex for electrophysiological research and computer information input].

A multichannel digital-to-analog system for polyfunctional physiologic studies requiring computer-ailed laboratory data processing is developed. The system performs an acquisition, conversion and recording of functional parameters. Built in the system additional units make it possible along with recording and digitizing the input information to record data on a tape recorder with further loading to a computer. Described in the paper is the unit complex that permits simultaneous recording the electric, locomotive and evacuant intestinal activity under experimental conditions and subsequent computer-aided data processing.

Analog-Digital Conversion↗
PubMed1984

Digital subtraction angiography in ischaemic cerebrovascular disease.

Digital subtraction angiography is a safe relatively noninvasive way of directly visualizing the major head and neck arteries, particularly by the venous route. It is the method of choice for investigating ischaemic cerebrovascular disease, and it may also be performed on an outpatient basis.

Analog-Digital Conversion↗
PubMed1984

[Method for the automated mapping of 35 ECG leads].

The method of recording the ECGs, inputting them into a computer and automatic analysis of 35 ECG leads is described. The proposed method largely diminishes the time expenditure and difficulties in obtaining and analysing 35 ECG lead mapping grams, as the computer makes all measurements and calculations and produces a final document.

Analog-Digital Conversion↗