The second E. C. Workshop on Ultrasonic Tissue Characterization was organized for the assessment of research goals and plans as the basis to a grant proposal for a "Concerted Action" which will be forwarded to the European Commission. It should, therefore, not only be considered as a work in progress exhibition which succeeded the former activities within the E. C. (Inventory on Tissue Characterization in Europe and first Workshop). The Steering Group invited a 1 imited group of Institutes to send its group leader and a research fel low in the entitled field, who should expose the overall research program, as wei 1 as the more specific work on tissue characterization by RF signal analysis and spectroscopy. The ultimate goal of the Workshop has been the formulation of schemes of interaction among the Institutes and individuals and the definition of cooperative research programs. The remainder of the groups and some of the groups present are working in the field of analysis and processing of cl inical A- and B-mode echograms (i. e. video signals). Because this work is more closely related to the cl inical diagnostics it was decided that for that reason no preparatory workshop was needed. In the final proposal for the Concerted Action this work wi 1 1 get ample attention. Although not many clinicians were present, their positive interest in the sophisticated analysis techniques and their contribution to the dis cussions again have been a most valuable and stimulating experience.

Ultrasonic Scattering in Biological Tissues contains 14 chapters written by world-renowned authorities who describe current work related to theoretical and experimental aspects of ultrasonic scattering phenomenon in biological tissues. Introductory material regarding ultrasonic scattering in biological tissues is presented, followed by discussions on theoretical treatments, experimental approaches, in vitro results on selective tissues, in vivo results on various tissues, and the current status of quantitative backscatter imaging. Ultrasonic Scattering in Biological Tissues will be an excellent reference for biomedical engineers, ultrasound specialists, biophysicists, and radiology researchers.

This symposium is the fourth of a series of scientific meetings in the field of echocardiology, held at the Erasmus University, Rotterdam.* The series was initiated by Klaas Born, who organized the first two meetings, and was continued by Charles Lancee. These previous symposia met with great success. These proceedings comprise most of the invited lectures and free commu nications which had their' live performance' during the 4th Symposium on Echocardiology. We decided, again, to maintain one ofthe most striking features of the last meetings: having the proceedings available at the time of the meeting. As a consequence, the authors-to-be were confronted with a very tight schedule. The editing time was also limited and therefore neither terminology nor units have been completely standardized. However, as a result, these proceedings do reflect the 'state of the art' in echocardiology. This is not a textbook on echocardiology, but cardiologists and techni cians, with experience in the field of echocardiology, will certainly appreciate the educational features of this book. This symposium was organized in association with Interuniversity Institute of Cardiology, Amsterdam, the Netherlands. Dutch Society of Ultrasound in Medicine and Biology Dutch Heart Foundation, The Hague, the Netherlands European Society of Cardiology Financial support was given by Interuniversity Institute of Cardiology, Amsterdam, the Netherlands University-fund Rotterdam Foundation, Rotterdam, the Netherlands Dutch Heart Foundation, The Hague, the Netherlands.

Many noninvasive examination methods of the heart have not held out against the invasive methods, which modern cardiac therapy, surgically or with catheterization, requires. They have disappeared completely or are only used by isolated groups of researchers. However, there is an obvious tendency to apply the invasive procedures as the last diagnostic possibility. In the attempt to select clinically relevant methods, the expert authors of this book demonstrate that echocardiography, expanded with contrast and Doppler, has been developed into one of the most important noninvasive methods. The results with tissue characterization show that the possibilities of this method have not yet been fully explored. Nuclear procedures are widely used, although they should only be applied in direct connection with clinical cardiology. The new lead methods of the ecg, such as ecg-mapping, show that standard electrocardiography of electrical functions is not yet fully exploited. The rapidly developing method of computer tomography is also being applied to cardiology. Since nuclear magnetic resonance requires extensive equipment con struction, its future is as yet unsure. Of course, a book like this does not intend to treat the subject of noninvasive cardiology in extensive detail. Established methods like standard electrocardio graphy, phonocardiography and sphygmography are not discussed. The aim of this book is rather to demonstrate the trend of present developments in the field. LIST OF CONTRIBUTORS Ameling, W., Rogowski-Institut fUr Elektronik, Rheinisch-Westfalische Technische Hochschule, Goethestrasse 27/29, D-5100 Aachen, FRG. Bachmann, K., Medizinische Poliklinik, Universitat Eriangen-NUrnberg, Ostliche Stadtmauerstrasse 29, D-8520 Erlangen, FRG.