Third European congress on ultrasonics in medicine

Third European Bologna, Italy, l-5

congress

on ultrasonics

October 1978

The Congress was held in the Palazzo dell Cultura e dei Congressi di Bologna which is approximately 2 km from the centre of the city. It is a well-equipped, purpose built conference centre containing two large lecture theatres and numerous smaller seminar rooms. The Opening Ceremony started at 10.00 a.m. on Sunday. The opening addresses were given in Italian and although simultaneous translation facilities were provided, several participants were asked to surrender their passports in exchange for some earphones! As most people didn’t have their passports handy, and couldn’t find where to plug in the earphones, I’m afraid the addresses may have lost something in the translation. The opening session ended with an excellent lecture given by Dr P.N.T. Wells entitled ‘A look into the future of ultrasound’. The scientific sessions commenced with a workshop on ‘automatic and computer aided sonography’. The workshop was excellently orchestrated by Klaus Born from Rotterdam and the fact that a very large audience was present throughout the session, was due in a large part to his efforts. The first paper was presented by George Kossoff and was devoted to the computer processing of grey-scale echograms from the Octoson ultrasonic scanner. Although radio frequency line mode and video line mode acquisition was discussed, the only really feasible acquisition system at present is the the section mode. This corresponds to the information stored on a conventional B-mode echogram and all information concerning the spectral content of the received echoes and the location of individual lines of sight is lost. Examples of amplified windowing and amplitude histograms of particular areas of the scan were presented. Decker and colleagues from Bonn presented a paper on computer aided tissue differentiation in ophthalmology. They discussed the generation of an object-specific ultrasonogram and features for tissue characterization. These features include, in the time domain, differences in impedance, absolute damping, amplitude modulation and morphological signatures. In the frequency domain the features are the spectroscopic content of the echo surface and attenuation of interior echoes, and in the phase domain, the phase/frequency and phase/time characteristics, and phase shifts. Johnson and colleagues from the Mayo Foundation, described reconstruction tomographic techniques and aperture synthesis methods for in viva investigation of the human breast. They also discussed methods of automatic recognition of diseased tissue regions. Vogel and colleagues from Rotterdam discussed computer analysis of M-mode echocardiograms. They use the computer in two ways, firstly. for the standard routine analysis such as valve leaflet velocity, and amplitude of movement, and secondly for tracing cardiac structures over one or more cardiac cycles. All data handling is carried out in an interaction between user

140

and program

in medicine

via a digitizing

tablet

and tv monitor.

Woodcock and Skidmore from Bristol discussed computer analysis of Doppler data. They showed that computers helped in two ways, firstly, in the processing of Doppler-shift signals so that they may be presented in a convenient form for display, and secondly, in the analysis of these signals to quantify the variation of blood-velocity over the cardiac cycle. Time and frequency domain analysis techniques were discussed. Emiliani and co-workers from Florence discussed data acquisition. storage and processing in the study of moving organs. They showed that complex digital image elaboration cannot yet be applied in continuous rcatime processing. Optical processing promises this feature together with a high information density. Somer from Maastricht discussed optical signal processing in ultrasound. In what turned out to be a very interesting lecture, he explained the fundamentals of optical processing, and described a system potentially suited to process the echo signals as received by a phased array, pulsed echo system in real-time and in two dimensions. Wessels and colleagues from Mainz discussed the recognition of patterns in ultrasonic sectional pictures of the prostate, with particular reference to tumour diagnosis. Techniques such as inverse and matched filters were used and demonstrated. Gros and Dale from Strasbourg described the numerical analysis of tomographic breast echograms. The workshop ended with a question and answer session and general discussion in which the point was made that computers have not made the expected impact in routine clinical diagnosis. On the Monday the scientific sessions proper got under way with five simultaneous sessions on cardiology. engineering and new techniques. internal medicine, gynaecology, and neurology related to blood vessels. Because of the parallel sessions, it is not possible to give a detailed description of the various sessions but only what the reporter was able to get to. In the session on neurology (vessels), nine papers were presented, all of which were concerned with Doppler investigations. There were very good broad-ranging papers from Pourcelot, Kaneko, Mol, and von Reutern on the application of Doppler devices in the study of the cerebral circulation. More specialized contributions were presented by Hodek-Demarin from Zagreb on the study of supratrochlear artery flow patterns, from Gratzl on the use of continuous wave Doppler in microvascular neurosurgery, and from Liboni on the influence of intracranial pressure changes on flow velocity in the carotid and jugular system. Denis White rounded off the session with some excellent colour scans of cerebral blood vessels using the scanning Doppler technique. The gynaecology workshop discussed the comparison between ultrasonography and other diagnostic procedures in pelvic and breast diseases. The engineering and new techniques session opened with a contribution from Furiozzi and colleagues from Florence who described an annular transducer array,

ULTRASONICS.

MAY 1979

and showed some Schlieren pictures of beam profiles. Kruizinga and Thijssen from Nijmegen discussed analysis of echograms in the time domain by means of complex demodulation. They analysed A-scope signals from the eye using inverse filtering techniques and by convolution of a series of delta functions with the envelope of the echo signal. They concluded that complex demodulation techniques were very sensitive and accurate techniques for measuring the times of arrival of overlapping echoes. Bredal and co-workers from Ispra, used digital computer methods to analyse UCG echoes and to linearize photographic film characteristics. Data was fed into the computer from original recordings by use of a tv camera. Assenza and Pappalardo from Rome described experiments with dynamic focusing. Their transducer had 95 elements, of which 32 were actuated at one time. It was capable of being focused in both transmission and reception although at the present time it is only focused in transmission. They showed a film in which images of phantoms and a human hand were shown. This was followed by an interesting contribution from Hassler and Honig from Erlangen who discussed the problem of resolution in ultrasound B-scan systems. By means of various silicon plastics phantoms containing rough and smooth inserts they demonstrated that a wide lateral ultrasonic beam produces poor longitudinal resolution, whereas narrow lateral beams do not. Hall and Fleming, from Glasgow, discussed errors inherent in the electronic determination of areas and perimeters of ultrasonic images, and a paper was read on behalf of Peter Fish, which showed the latest results from an integrated system for blood vessel imaging and blood flow measurements. This session continued after a break for coffee, and included contributions from the Thorax Centre in Rotterdam on miniaturization of two-dimensional imaging, several contributions from Japan on high speed sector scanning and a three-dimensional display system for ultrasonic diagnosis, based ‘on computer analysis of a series of stored B-scans. Phil Green, from the Stanford Research Institute discussed advances in transmission imaging including pictures from the SRI camera. The cardiology session discussed the value of echocardiography in out-patient departments. Discussion varied over the study of heart enlargement, the detection of atria1 tumours, the use of real-time B-scan and M-mode displays in the diagnosis of hypertrophic cardiomyopathy, and in assessment of patients after valve replacement. On the Monday afternoon the only scheduled programme was a workshop devoted to tissue characterization. The workshop was divided into two sections, namely clinical needs and technical possibilities and limitations. In the clinical needs session Professor Weill from Besancon discussed internal medicine, Dr Kratochwil, Vienna, discussed problems in gynaecology and breast disease, Dr Gibson, London, discussed cardiology and vascular disease and Dr Buschmann, Wurzburg, talked about opthalmology. The overall feeling, voiced particularly by Dr Buschmann, was that equipment manufacturing standards were needed. In the ‘technical possibilities’ session contributions were made by Professor Lizzi, New York, on multi-frequency

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MAY 1979

analysis. He concluded that it is necessary to combine scattering techniques with conventional B-scan equipment. Dr Nicholas, from Sutton, described work on pattern recognition and diffraction analysis. Dr Carson, Denver, discussed the reconstruction of interaction coefficients. Dr Perronneau, Paris, looked at Doppler blood flow analysis, and Mr Dickinson described the important questions posed by tissue and organ movement. The discussion was well orchestrated by Dr. Hill, Sutton, and the general feeling seemed to be that to increase the useful diagnostic information available using ultrasound, techniques such as scattering, diffraction and reconstruction must be based on sound physical knowledge and that once the ground work was laid, these areas of investigation would promise much. On the Tuesday morning there were again five parallel sessions which included a workshop on internal medicine, cardiology, gynaecology, obstetrics and neurology. The internal medicine workshop dealt with comparisons between ultrasound and various other imaging techniques in the study of various organs and tissues. Fromhold and Koischwitz from Bonn, compared ultrasound with scintigraphy and CAT scanning, for investigations of the liver. In a study of 138 patients they showed that in general ultrasound was better than scintigraphy and was approximately the same as CAT scanning. For investigations of the gall-bladder and biliary tree, Weill from Besancon, said that there was no reason to use CAT scanning to diagnose gallstones, and for jaundice only ultrasound should be considered. Successful diagnoses were made in 92% of cases using ultrasound. He also said that radioisotopes only played a part when bowel gas obstructed the ultrasound scan. For investigating liver structures and the gall-bladder, ultrasound was better than CAT scanning except in the case of tumour detection. He concluded that CAT scanning was sometimes better than ultrasound for visualizing in the pancreatic area. Biggi and colleagues from Genoa considered that for investigation of the kidney, ultrasound is the primary investigative method. In cases of acute infectious diseases ultrasound and CAT scans are both useful. Ultrasound successfully detected simple renal cysts in 95% of cases, malignant cycts in 67%, polycystic kidney 92%, hydronephronesis 97% and in renal tumours, 88%. They only consider CAT scanning after ultrasound. Professor Weill reported on the pancreas, in place of Dr Heckeman from Essen. Weill showed that in cases of acute pancreatitis ultrasound usually showed swelling of the pancreas with heterogeneous echoes. Chronic pancreatitis was correctly diagnosed in 96% of cases. Carcinoma presented as swelling of the pancreas which also appeared sonoluminescent, and was correctly diagnosed in 92% of cases. In investigations of the retroperitioneal space Dr de Winter from Brighton showed that, in general, CAT scanning is to be preferred to ultrasound. The afternoon sessions on Tuesday were taken up with administrative sessions of the various national societies and a general assembly of the delegates of the European Federation. On the Wednesday morning three workshops were held simultaneously These were devoted to ophthalmology. obstetrics and neurology. The ophthalmology workshop covered the use of A-scan, grey-scale and CAT scanning

141

in the investigation of orbital turnout-s. In the obstetrics workshop the main topics were dynamic criteria of embryo-fetal health. Papers were presented on fetal movements and fetal motor behaviour during pregnancy, the diagnosis of fetal malformations, fetal cchocardiography, and fetal breathing. The neurology brain pathology workshop discussed the impact of CAT scanning on echoencephalography. Concurrent with these workshops were sessions on cardiology and internal medicine. Part of the cardiology session was devoted to the study of Doppler flowmeters in peripheral blood vessels, coronary artery reconstructions and the measurement of volume flow in deep-lying blood vessels. The first part of the internal medicine session was devoted to a study of the hepato-biliary system and the second part to a study of the breast. On the Wednesday afternoon there were five parallel sessions devoted to ophthalmology, internal medicine, tissue characterization, gynaecology/obstetrics and physics. By this time the information being presented at the various clinical sessions was becoming a bit repetitive and it was quite refreshing to see a session on physics. The first part of this session was deveoted to the problems of power measurement and the characterization of transducers, and it was nice to see this being chaired by Dr C.N. Smyth, who was interested in these problems while some of us were still practising fetal breathing. The highlight of the second part of the physics

section was the presentation of the work on transmission imaging by Dr P. Green and colleagues. The Thursday morning sessions were the last that this reporter attended due to an afternoon departure to Rome. However, there was a useful workshop on the dosimetry control of ultrasound and standardization of equipment. Dr K. Shotton from the National Physical Laboratory discussed the establishment of UK national standards, Dr C.R. Hill discussed the work and rcsponsibilities of international agencies and Dr J.C. Aller from Washington discussed the status of standards in the USA. Professor Nyborg (Vermont) reviewed the biophysical basis for dosimetry control and Dr Breyer (Zagreb) discussed system performance. On the lighter side there was during the course of the meeting an excellent Conference dinner at the Palace of King Enzo, at which we were entertained to some delightful flute and guitar playing. This third European Congress was a large and complicated affair and must have presented many problems to the organizers. On the whole, things went very well, and the organizing committee deserves our thanks. It was an opportunity to meet again colleagues from Europe and the United States and we look forward to the Fourth Congress in Yugoslavia in 1981. J. Woodcock

Modern Edited Books

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below

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from

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are

or those

the publishers.

them

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being

those

recently

mentioned Their

received

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reviewed

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here

in a later

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issue.

problems

in elastic wave propagation

by J. Miklowitz,

Wiley-Interscience

J.D. Achenbach

(1978) x + 561 pp, f23.00

Orbit Roentgenology Edited

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Wiley Medical (1977) xiii + 274 pp, f36.70

Acousto-optics Specification for hydrophones poses (BS 5653: 1978)

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Wiley (1979) xv + 126 pp, f8.00

British Standards

Handbook Edited

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(1978) 11 pp, f4.80

of clinical ultrasound

by M. de Vlieger,

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Wiley Medical (1978) xviii + 970 pp, f42.50

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Institution

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Ultrasound Edited

in tumour

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diagnosis

V.R. McCready,

0.0.

Pitman Medical (1979) vii + 285 pp, fll

Cosgrove

.OO

ULTRASONICS.

MAY 1979