PubMed Health⌕ Search

Biomedical subjects

W Ameling

Publications and source records attributed to W Ameling.

At least 19 recordsLinked to original sources
PubMed1992

Initial experience with a multiplane transoesophageal echo-transducer: assessment of diagnostic potential.

BACKGROUND: the prototype of a transoesophageal echocardiographic transducer with a rotatable cross-sectional scanning plane underwent initial evaluation. METHODS: the 5 MHz, phased array, 64 element transducer is incorporated into a 16 by 11 by 40 mm echoscope tip. The instrument also has pulsed wave and colour flow Doppler capabilities. Exterior controls allow continuous mechanical rotation of the scanning plane from 0 degree, corresponding to the conventional transverse plane, through 180 degrees, thereby encompassing all possible planes. RESULTS: 103 patients underwent examination without complications; two additional patients were excluded because of difficulty in swallowing the probe. Advantages include precise alignment of aortic valve long- and short-axis views, long-axis views of the ascending aorta (mean visualized length: 6 cm), and full scanning of the entire circumference of the mitral valve and the left ventricle. Separation of paravalvular and transvalvular leakage in prosthetic valves is distinctly improved. CONCLUSION: multiplanar transoesophageal imaging is feasible and increases the diagnostic yield, especially in mitral and aortic pathology and in the assessment of left ventricular wall motion. Three-dimensional reconstruction is an attractive potential application.

Adult↗
PubMed1992

[Initial clinical trial of a multi-planar transesophageal echoscope].

The prototype of a multiplanar transesophageal echocardiographic transducer was evaluated clinically. This 5 MHz, phased array, 64-element transducer allows to continuously rotate the imaging plane from the transverse (0 degree) position to a maximal 180 degrees position, thus encompassing transverse, longitudinal, and every intermediate position. The transducer is incorporated in the echoscope tip measuring 16 by 11 by 40 mm. The shaft of the instrument is 110-cm long and has a 9-mm diameter. The instrument has pulsed wave, continuous wave, and color Doppler capabilities. 176 clinical patients were examined with the multiplane transducer. No complications occurred. Advantages of this transducer included: 1) comprehensive scanning of the whole mitral circumference and mitral valve; 2) quick and precise alignment of aortic valve long and short axis views, including long axis views of the ascending aorta, with a mean visualized length of 6 cm; 3) improved imaging and evaluation of transvalvular and paravalvular regurgitant jets in mitral and aortic valve prostheses; 4) complete evaluation of all left ventricular segments using multiple planes from transgastric and transesophageal transducer positions. An important potential application is three-dimensional reconstruction of cardiac structures and color Doppler jets.

Adult↗
PubMed1989

[3-dimensional organ representation with ultrasound. Experimental studies--computer simulation].

This is the first report on the 3-dimensional representation of organs with US. The prerequisite for this was a coordinated transducer movement, in such a manner that the organ under examination was represented by US sections differing in only one of the space coordinates. Such transducer movement was made possible by 2 devices. In the first instance, longitudinal movement of the transducer resulted in the production of parallel sections of the organ while, in the other instance, rotation of the transducer head permitted sections arranged around a fixed center-point. Using a special computer program, the sections were contoured in such a manner that only the surface of the organ was represented. These sections were then arranged in space. The 3-dimensional representation can be effected both by binary image representation and by representation with closed (intact) body surface. The advantage of the binary image representation is the fact that the organ surfaces "extracted" from the original US sections are directly incorporated within the 3-dimensional image build-up, with no further computer manipulations. It can be seen that the rotation of the transducer head represents the practicable possibility for the use in the clinical setting.

Computer Simulation↗
PubMed1989

[Clinical application of 3-dimensional ultrasound display. Initial results].

Using a newly developed ultrasound transducer and a corresponding computer program, it proved possible to construct a three-dimensional (3-D) display--at 7, 9, 11 and 13 weeks of pregnancy, respectively--of three structures lying one inside the other: embryo, amniotic sac and uterus. By means of a special computer technique the three structures could be displayed both in relation to one another and singly. Spatial rotations of the reconstructed body can be displayed on the video screen as can the individual bodies in different cross-sections. With narrow angles between individual sections this method may become important in the intra-uterine diagnosis of malformations and also of neoplasms.

Amnion↗
PubMed1989

[Prerequisites for the clinical application of 3-dimensional ultrasonic imaging].

After satisfactory experimental results with three-dimensional data acquisition and presentation of the kidney in vitro, we wanted to show how our technique could be used for medical application in vivo, such as ultrasonic 3D reconstruction of organs. The sector scans were taken by rotating the scan head 10 degrees in any direction around the length of the axis. The organ was scanned with 18 images and reconstructed. The digital images, using the organ contours, allowed 3D reconstruction of the original organ, relying on the computer memory. The first results in reconstructing uteri show how this scan head can be used in combination with the computer programs for medical application. For the first time, it has become possible to present computer-generated views of an organ cross-section that has been impossible to obtain by means of traditional ultrasound techniques. Recent experiments using this method show new ways of diagnosing tumors.

Adult↗
PubMed1988

[Three-dimensional imaging in ultrasonic diagnosis. Initial results].

A new method of three-dimensional (3-D) reconstruction of 2-D ultrasound images of the kidney is described. It is based on a coordinated spatial reconstruction of sequential cross-sectional images. The ultrasound head is moved longitudinally between two rails (parallel sections) and rotated. With a suitable computer program and contouring of each cross-section (so that the organ limits are defined for the computer) these cross-sectional pictures can be reconstructed into 3-D organ images. The kidney can then be presented spatially either as a binary picture or with closed surface. Ultrasound investigators are still unaccustomed to colour reproduction of 3-D reconstructed organs. It remains to be seen whether the method is valuable in routine clinical use.

Color↗
PubMed1978

[Computer system for the automatic analysis of cath-lab data. Reliability of pattern-recognition and measurements (author's transl)].

The computer-system for the on-line-analysis of hemodynamic data developed in Aachen enables the clinical user to perform the immediate on-line analysis of ECG, pressure-curves and thermo- or dye-dilution-curves in a dialog mode. The procedure of pressure analysis as well as the calculations by the computer for the individual haemodynamic parameters are described. The comparison of the medical-manual evaluation of the pressure curves on paper-registration and the computer results of the same measurement shows a very good correlation for wave-recognitions and wave-measurements for this system, integrated in the daily routine since 24 months. As well in the application of various fluid-filled catheters used in praxis as in tip-manometers it could be proved for the pressure-analysis in the different positions of the heart, that the computer-system produced reliable evaluations for all catheter materials used. The flexible conception of the computer program with its fast adaption to new problems allows its use not only in the clinical routine, but also and especially in the handling of scientific questions in the frame-work of haemodynamic analysis.

Cardiac Catheterization↗
PubMed1977

[Detailed analysis of systolic and diastolic parameters in aortic valve disease (author's transl)].

The on-line computer-system for the analysis of cathlab data developed by us allows the immediate evaluation of the conventional pressure- and valve-opening as well as a new hemodynamic parameters. In addition the volume-analysis is performed by the videometry-program. In simultaneous pressure-volume-registrations the complementary calculation of important energetic items is possible. This expanded analysis by the aid of the computer-system enables a detailed pre- and postoperative study of great clinical-practical and scientific importance.

Aortic Valve↗