Spatiotemporal accuracy of real-time 3D echocardiography in the neonatal and pediatric setting--validation studies using small dynamic test objects.

UNLABELLED: The precision of real-time 3D-echocardiography (RT3DE) is not sufficiently validated for small, fast-moving structures such as the neonatal and pediatric heart. PURPOSE: To assess the spatiotemporal accuracy of RT3DE in small, moving test objects. MATERIALS AND METHODS: Small, calibrated test objects in the size of neonatal and pediatric heart chambers were made from polyurethane foam or metal wire mesh and moved in a water bath through a calibrated dynamic test system. Using matrix transducers (X7-2, ie33 and X4-1, Sonos 7500, Philips, Andover, USA), 2 D and live 3 D datasets under variation of the motion speed (0.033 - 0.133 m/s corresponding to 50 - 200 heart cycles/minute), the volume rate and transducer position were recorded and analyzed (QLab 7.0, Philips). RESULTS: 3 D datasets of the moving test objects showed relevant spatial distortion, which was obviously related to the sequential scanning technology of the matrix transducer. Different segments of a test object were not recorded simultaneously, but rather row-by-row, so that there was a time delay between the first and the last-recorded voxel of a single 3 D volume (mean±SD: 28.9 ±â€Š7.82 m/s or 80 ±â€Š7 % of the time duration of a 3 D volume). With increasing motion speed of the test object and reduced 3 D volume rate, the distortion artifacts increased significantly. CONCLUSION: 3 D acquisitions using matrix technology demonstrate relevant spatiotemporal inaccuracies. This may lead to misinterpretations during the evaluation of the synchronicity of valvular or ventricular motion and incorrect definition of volume estimations. In particular, at higher heart rates and higher rates of movement, these limitations have to be taken into account in clinical practice.

Volumetry of fetal hearts using 3D real-time matrix echocardiography - in vitro validation experiments and 3D echocardiographic studies in fetuses.

PURPOSE: The aim of this study was to assess the feasibility, accuracy and reliability of 3D real-time echocardiography for fetal heart volumetry. MATERIALS AND METHODS: Fifty unselected and consecutive fetuses, including 14 with cardiac malformations, were scanned prospectively using real-time 3D matrix technology and 2D echocardiography to determine ventricular volumes. Small phantoms as well as modified balloons (0.5 - 20 ml) were used to assess the validity of 2D and 3D distance, area and volume calculations and to study potential sources of error during data acquisition and analysis. The data was evaluated by two blinded observers. RESULTS: In vitro, real-time 3D and 2D underestimated the actual volumes by -5.49 % (3D) and -6.86 % (2D). The intraobserver and interobserver variability were excellent. In vivo, real-time 3D was superior to 2D with regard to intraobserver and interobserver variability (mean coefficient of variation 8.28 % (3D) versus 13.96 % (2D), and mean intraclass correlation coefficient 0.997 (3D) versus 0.885 (2D) for left ventricular volumes). Similar to in vitro, in vivo 2D volumes were calculated smaller than 3D volumes (mean difference -0.39 to -0.94 ml). The ventricular volumes and stroke volumes increased exponentially with gestation. Secondary to poor imaging windows in advanced gestation or inadequate delineation of endocardial borders in small hearts at less than 19 weeks, 3D data could not be analyzed sufficiently in 6 / 50 fetuses. CONCLUSION: Real-time 3D using a matrix transducer is a feasible, reliable and valid method for volume determination in the fetus beyond 19 weeks of gestation. If compared to 2D, real-time 3D echocardiography provides improved accuracy of cardiac volumetry, decreases intraobserver and interobserver variability and is a promising tool for the accurate assessment of cardiac size and function.

Super-reversed intraocular lens.

An intraocular lens (IOL) with an inverse (reversed) optic has the convex surface directed toward the retina, a design which has many advantages. We have developed a "super-reversed" IOL by increasing the angle of the haptic from 10 to 20 degrees and by increasing the convexity of the posterior surface (necessitating a concave anterior surface). The main advantage of this model is the distance of approximately 6.3 mm between the anterior corneal surface and the posterior IOL surface. This configuration mimics the natural situation. We report on the implantation of 473 lenses of this design.

Ocular tissue characterization by RF-signal analysis: results and experience of a 4 year in vivo-study.

A technique for Radio-Frequency (RF)-tissue characterization with hand-held transducer in the 5-25 MHz frequency range was clinically tested during 4 years on ocular tissues, especially on membranes, and tumours of the inner eye.

[Computed tomography of primary and secondary tumors of the eye and orbit]. / Computertomographie primärer und sekundärer Tumoren des Auges und der Orbita.

Only computed tomography (CT) is able to demonstrate ocular, orbital and peri-orbital soft tissues, calcification and bony structures directly and without superimposition of other tissues. 165 patients with tumours of the eye or orbit have been examined by CT and in 143 the diagnosis has been confirmed. The value of CT lies in its ability to demonstrate tumours and to define their orbital and extra-orbital extension and their relationship to neighbouring structures. In 51% of the lesions there was bone destruction and in 6% intracranial extension. Density measurements before and after intravenous contrast medium only rarely provided a specific diagnosis.

[Computed tomographic volumetry of the orbit in endocrine orbitopathy]. / Computertomographische Volumetrie der Orbita bei endokriner Orbitopathie.

The volumes of the four recti muscles and the orbital fat was measured by CT in 40 normal persons and in 60 patients with clinically confirmed Graves' disease. Compared with normal persons, 42 patients (70%) showed an increase in muscle volume and 28 patients (46.7%) an increase in the amount of fat. In nine patients (15%) muscle volume was normal, but the fat was increased. By using volumetric measurements, the amount of fat in the orbits in patients with Graves' disease could be determined.

[Magnetic resonance tomography (MRT) of the orbit]. / Magnetische Resonanztomographie (MRT) der Orbita.

By using high field strengths and surface coils, MRT achieves a resolution comparable with CT in the orbita. The advantages of MRT are good contrast resolution and imaging in several planes. Twenty-six patients have been examined by MRT, which has shown high sensitivity and good detail for the demonstration of pathological changes. In spite of this, MRT at present is not a realistic alternative to ultrasound and CT, because it is unable to demonstrate bone and calcification; its specificity is low, but the time and cost of the examination is high. It is indicated only for problems involving the optic nerve and chiasma.

[Functional properties of diagnostic ultrasound instruments. A concept of trial building blocks for implementing quality assurance]. / Funktionseigenschaften von Ultraschalldiagnostikgeräten. Ein Konzept von Prüfbausteinen zur Durchführung der Qualitätssicherung.

Today's medical diagnostic ultrasonic devices are complex technical systems and need adequate Quality Assurance (QA) with regard to ultrasonic safety and performance. As to ultrasonic safety the International Declaration Standard IEC 1157 issued in 1992 supports progress for design of future equipment. It will be increasing importance to connect and to balance out the requirements for acoustic safety and for the diagnostic potential of the equipment. In Germany the application of QA in ultrasonics has to consider limitations by structure. Against this background the author gives an overall view of QA for the performance of imaging and Doppler equipment. From recent technical and standardisation work expressing demands and solutions for QA derives a practical concept of a modular QA programme. As an example, the specific test steps and suitable instruments for the procedures are given for some QA programmes in B-mode and Doppler-mode (B, cwD, pwD). A proposal is made how to split up the QA programme into a level 1 left to the medical personnel and a level 2 put to practical use by technical services or equipment distributors.

[Ophthalmologic ultrasound diagnosis--current training programs in Germany, Austria, Switzerland]. / Ophthalmologische Ultraschalldiagnostik--zur heutigen Ausbildungssituation in den Ländern Bundesrepublik Deutschland, Osterreich, Schweiz.

In these three countries the application of diagnostic ultrasound in ophthalmology is restricted, with few exceptions, only to institutions having access to in-patients. This situation is based on the organization of medical care and does not depend on the technical evolution of the equipment. Consequently the annual rate of trainees in ophthalmic ultrasound is relatively low, but a comprehensive training programme is needed in this field. The requisite training subjects are described. They include a technical and a clinical programme for both pulse-echo (A, B, M, D mode) and Doppler techniques as applied for biometry as well as for tissue and vascular examination. Some data are given regarding training facilities, aids and courses in the three countries. The concept and organization of a 5-day course (Bonn/Würzburg Course, Directors: W. Buschmann/H.G. Trier) is described in greater detail. For ophthalmic ultrasonography, testing and calibration of system parameters both for equipment and transducers is necessary for obtaining reliable and reproducible results. Examples are given for the organization of technical training in the practical course. The 1981 guidelines of the "Kassenärztliche Bundesvereinigung", Cologne, are discussed. These regulations define minimum requirements for both ultrasonic training and equipment in the FRG. Finally, a few controversial aspects of the teaching (quality assurance, role of biometry) are mentioned.

[Use of ultrasound in ophthalmology]. / Zur Ultraschallanwendung in der Ophthalmologie.

In ophthalmology, ultrasound is applied in diagnostics as well as in surgery and therapy. This paper gives a short survey on both applications. Ultrasonic phacoemulsification is of considerable practical importance for modern cataract micro-surgery with intraocular lens implantation. Applications of that kind require consideration of ultrasonic bioeffects and equipment safety. Diagnostic use of ultrasound includes biometry (echometry), tissue examination and characterization, and vascular investigations in eye and orbit. The application of diagnostic ultrasound on in-patients, its individual indications, and the appropriate methods (A, B, automatic biometric devices for axial length measuring, M, Doppler) are described. Examples of commercially available instruments for the different applications are given. In comparison with other disciplines ophthalmic A-mode and B-mode echography is characterized by: refined depth resolution and lateral resolution; the important part of quantitative methods for clinical evaluation of echograms; and the advanced level of quality assurance for equipment performance. Refined tissue evaluation requires optimized and reproducible equipment parameters. To ensure these conditions the clinical echographer must be educated and willing to test performance and quality of his equipment. Finally, a perspective of actual research in diagnostic ultrasound of the eye is given.

[Quality assurance for diagnostic ultrasonic equipment in A- and B-mode in ophthalmology (author's transl)]. / Zur Qualitätskontrolle von Ultraschalldiagnostik-Geräten für A- und B-Bild-Verfahren.

Quality assurance for diagnostic ultrasound in ophthalmology is of growing importance and will be the subject of new standards and regulations. Methods for equipment performance testing by means of electric test signals in A- and B-mode equipment are described, both for comparative evaluation of equipment and for routine quality assurance tests. Newly developed test signal generator for checking the time scale in ultrasonic biometry of the eye are presented.

[Quality assurance in ultrasound diagnostic equipment in West Germany. Experiences with current regulations]. / Zur Qualitätssicherung bei Ultraschalldiagnostikgeräten in der BRD. Erfahrungen mit den heutigen Regelungen.

Since 1980, the Health Service (KBV) of the FRG has introduced regulations for quality assurance of diagnostic ultrasound equipment. This step was taken to limit overshooting expansion of echography and Health Service costs. The author describes experiences and problems arising from application of the KBV regulations. Preventing diagnostic ultrasound from developing institutional structures and being included in existing health and safety acts, resulted in a lack of legitimate and qualified structures for quality assurance of the methods. This deficiency of structures also compromises the quality assurance by KV regulations and thus produces an administrative torso. Therefore, in West Germany, the first step to improve quality assurance ought to be to look for appropriate institutions for qualified equipment testing.

[The Doppler Simulator DS 81. A new calibration method for ultrasound-cw-Doppler blood flow measurement devices]. / Der Doppler-Simulator DS 81. Eine neue Kalibriermethode für Ultraschall-cw-Doppler-Blutfluss-Messgeräte.

Quality assurance in commercial cw-Doppler devices demands the use of special techniques in providing reproducible, optimized patient examination conditions for the individual instrument, and to permit a comparison with results obtained by other equipment. Equipment can be tested on two different technical levels: by checking the total performance by means of a Doppler phantom, or by testing the relevant components by means of electrical test signals. The use of Doppler phantoms involves certain drawbacks with respect to some equipment parameters and the routine equipment check. In the German Federal Republic, new official regulations (KBV), including the minimum requirements for Doppler equipment have been issued. To fulfil the legal requirements, a special test device, The Doppler Simulator DS 81 (1981), has proved suitable. The device provides a graduated scale of discrete, synthetic Doppler frequencies; these are fed into the Doppler equipment under test, and the response is recorded on the instrument's strip chart recorder or viewing screen. They are used as reference frequencies and for calibration. This method represents a further step towards reproducible or quantitative Doppler sonography.

Computer-aided ultrasonic measurements of the corneal thickness.

This report regards the measurements of the central corneal thickness by means of a computerized ultrasonic biometry system that had been developed by the authors. The characteristics of this system are: (a) a data rate of 10 measurements/s (reduced from the technical maximum of 800/s); (b) a resolution of 0.02 mm, and (e) statistical evaluation of data by automatic measurement histogram. The preliminary results on models and living human eyes suggest an equivalence of the improved ultrasonic measurement in cases where an immersion technique is feasible, with optical methods usually applied in clinical routine.

[First experiences with an instrument for TV display of digitally encoded text information for the visually handicapped (author's transl)]. / Erste Erfahrungen mit einem Gerät zur Darbietung digital kodierter Texte auf Fernsehgeräten für Sehbehinderte.

An instrument was developed which allows the display, in enlarged form--especially for visually handicapped persons--of text information as used in modern data-acquisition systems such as writing automats, screen editing devices, and television text display (in England, Ceefax). With the aid of electronic character generators, the text is displayed continually, moving from right to left in one line on the screen of a commercial TV set. Rate of movement, size, brightness, and color of the characters (and/or the background) can be selected arbitrarily. We performed a preliminary reading test with visually handicapped subjects from a rehabilitation center for blind persons. The resulting optimal parameters for text display and the achieved reading speed with the system are discussed.

[New technique of ultrasonic biometry (author's transl)]. / Neuartige Ultraschallbiometrie.

A new measuring system for echo return times is described, which renders it possible to measure simultaneously the three axial lengths of the living eye (length of cornea plus anterior chamber, length of the lens and of the vitreous) with ultrasound in real time and to process the data numerically. The repetition rate for the measurements is optimized up to the limit: each transmitted wave is registered. The computer either generates a measuring protocol with statistical data (mean value, standard deviation) or the variation of the three echo return times is displayed graphically. In clinical practice the unit is used routinely for rapid determination of optimal implant lenses, etc.

[An extremely malignant uveal melanoma]. / Extremes malignes Uveamelanom.

The authors present an extremely pronounced involvement of the orbita in malignant uveal melanoma with a ten-year course of disease. The results of imaging diagnostics (ultrasound, computed tomography, magnetic resonance tomography) are discussed.