Selskabets kasserer Overlæge dr.med. Niels Fogh-Andersen præsenterer deltagerne i foredragskonkurrencen.

Der var indsendt 24 abstracts til foredragskonkurrencen hvoraf 6 blev udvalgt til mundtlig præsentation ved jubilæet. Dommerkomiteen havde en særdeles vanskelig opgave, da alle abstracts var af høj kvalitet. Af de 6 udvalgte blev de tre 'bedste' præsentationer præmieret med henholdsvis 10.000 kr., 5.000 kr. og 3.000 kr.

Selskabet har udgivet en jubilæumsbog om medicoteknikken i Danmark gennem de sidste 25 år. Bogen er uundværlig for alle der interesserer sig for medicotekniske emner og den kan købes for 100,- Dkr.!

Hjerte-lunge-karkirurgisk afd. T, MR-centeret, Inst. For Eksp. Klin. Forsk., Skejby Sygehus, 8200 Århus N

Udvikling, evaluering og applicering af den tre-dimensionel paraboloide MR metode til bestemmelse af flow, wall shear stress og karlumens areal

Formålet med dette Ph.D. projekt var dels at udvikle en ny matematisk metode til at kvantitere wall shear stress (WSS) og karvægsposition meget nøjagtigt ved hjælp af magnetisk resonans (MR), dels statistisk at evaluere metoden vha. computer simuleringer, in vitro og in vivo målinger. WSS er et udtryk for det flydende blods mekaniske påvirkning af karvæggen.
Den udviklede metode udnytter den vældige mængde data MR opsamler og var baseret på nogle relativt simple hæmodynamiske forudsætninger. Fitning af blodstrømshastigheds data tæt på karvæggen til en tre-dimensionel paraboloid (3DP) muliggjorde bestemmelse af volume flow, subpixel karvægs position, kardilatation og WSS.
Computer simuleringerne viste, at metoden er både nøjagtig og meget insensitiv til støj i data. I peak systole var 95% af computersimuleringernes fejl inden for ± 0.5% (volume flow), ± 1.1% (kar areal) and ± 2.3% (WSS). In vitro blev det luminale areal estimat fundet med en gennemsnitlig fejl på 0.6%. 95% sikkerheds intervallet inkluderede den specificerede 8.00 ± 0.01 mm diameter glasrørs dimensioner. In vivo resultaterne er meget lovende og har afsløret mere komplicerede flow og WSS forhold i halspulsåren end hidtil antaget.
En ny meget lovende metode er blevet udviklet. Dette er den første metode, som finder karvæggen noninvasivt med µm (±50) nøjagtighed i hele dens omkreds.

Center for Fast Ultrasound Imaging, Department of Information Technology, build. 344, Technical University of Denmark, DK-2800 Lyngby, Denmark

Measurement of the blood velocity vector using ultrasound

In medical ultrasound the blood velocity in a vessel can be found by emitting a pulsed field into the patient. The movement of the red blood cells is the basis for the detection and estimation of the velocity. It is a well-known limitation of all commercially available scanners that only the velocity component along the propagation direction of the emitted pulse is measured when evaluating blood flow with ultrasound.
A method for estimation of the velocity vector is presented. An ultrasound beam is generated, so that a transverse motion yields a change in the received signals.
The method uses two ultrasound beams for sampling the in-phase and quadrature component of the lateral field, and a set of samples (in-phase and quadrature in both time and space) are taken for each pulse-echo line. These four samples are then feed into a two-dimensional autocorrelation approach that yields both the axial and the lateral component of velocity vector, and thus the velocity vector. The method has the advantage that a standard array transducer and a modified digital beamformer, like those used in modern ultrasound scanners, is sufficient to obtain the information needed. Estimation results based on measured data are presented.

Center for Fast Ultrasound Imaging, Department of Information Technology, Build. 344, Technical University of Denmark, 2800 Lyngby

An approach for three-dimensional real-time ultrasound imaging

One of the main applications of ultrasound imaging is in cardiology, where a real-time cross-sectional image of the heart is used for diagnosis. The image does not readily display the complicated 3D structure of the heart, and it would be beneficial to have a dynamic 3-D view, in which the physician can study the dynamic anatomy, spatial relationships of the moving structures and the haemodynamics.
In order to obtain 3D images with a good spatial resolution, it is necessary to obtain 64×64 scan lines. The necessary time to acquire a scan line is about 200 µs, which gives a frame rate of 1.2 Hz, too low for cardiac applications. One possible solution of the problem is to form multiple beams in receive.
In current systems, high resolution and contrast in the images are maintained by using phased array transducers with at least 64 elements. For the 3D case, it would be necessary to have a 2-D phased-array transducer that consists of 64 by 64 elements, i.e., 4096 transmit and receive channels, a too large number for practical implementation.
The talk describes an approach to obtain 3D images with a high contrast and resolution using different sparse-array transducers to transmit and receive. The proposed technique requires only 121 transmit and 64 receive channels. It also enables parallel beam forming in receive. Realistic, simulated 3D volume images are presented to evaluate the performance of the proposed 2D geometries for transducers design. A frame rate of 15 Hz can be attained.

Publikum lyttede opmærksomt.

Se de 3 øvrige deltagende foredrag.

Efter foredragskonkurrencen forsatte dagen med en jubilæumskonference under titlen "Har medicoteknikken en fremtid i Danmark"

Udviklingen inden for røntgen, CT, MRI og ultralyd blev omtalt sammen med den nuværende danske indsats inden for billeddiagnostiske systemer.

Formanden holder festtale og lykønsker vinderne af foredragskonkurrencen.

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