This volume is the scientific chronicle of the NATO Advanced Research Workshop on Computational Aspects of the Study of Biological Macro molecules by Nuclear Magnetic Resonance Spectroscopy, which was held June 3-8, 1990 at Il Ciocco, near Barga, Italy. The use of computers in the study of biological macromolecules by NMR spectroscopy is ubiquitous. The applications are diverse, including data col lection, reduction, and analysis. Furthermore, their use is rapidly evolv ing, driven by the development of new experimental methods in NMR and molecular biology and by phenomenal increases in computational perfor mance available at reasonable cost. Computers no longer merely facilitate, but are now absolutely essential in the study of biological macromolecules by NMR, due to the size and complexity of the data sets that are obtained from modern experiments. The Workshop, and this proceedings volume, provide a snapshot of the uses of computers in the NMR of biomolecules. While by no means exhaustive, the picture that emerges illustrates both the. importance and the diversity of their application."

The basic principles of the phenomenon "erection" have been known since the pioneering work of Kolliker, Eckhard and Langley in the nineteenth century. Nonetheless, under the influence of Freud, erectile dysfunction was predominantly at tributed to psychogenic factors. A more liberal perception of sexuality since the 1960s, the development of new and refined diagnostic techniques, and the expansion of basic research activity resulted in a new concept of erectile dysfunction, identifying arteriogenic, venogenic, endocrinologic or myopathic (cavernous smooth muscle dysfunction) factors. From this research other considerations such as autonomic innervation, cavernous endo thelial intactness or impaired neurotransmitter pool are being introduced into routine clinical assessment. A reevaluation of psychogenic etiology with a consequential new concept of psy chogenic impotence is on the rise. In this book the new concepts of basic knowledge on cavernous smooth muscle function and its supraspinal, spinal, and local control; the new diagnostic approaches in psychogenic and autonomic factors; and the new developments of reconstructive therapeutic options for the patient have been tied together. Outstanding and internationally renowned experts in the field of erectile dysfunction have given detailed insight into the latest basic and clinical developments. Well-established diagnostic and thera peutic techniques are presented by experienced colleagues. We hope that this book will help the reader to get an overview of the current concepts of erection. Furthermore, we hope that international collaboration in basic and clinical research in the field of erectile dysfunction will render an update necessary in the near future.

"Endourology" provides a summary of the different endourological modalitites, especially the more advanced and controversial techniques, such as the antegrade resection of urethral valves, the transperineal I 125 seed implanations, the spoonloop resectoscope, flexible endoscopy, teflon injection to correct vesicoureteral reflux, stone manipulation in calyceal diverticula, as well as the extraperitoneal pelvioscopy. These techniques are supported by descriptions of the standard endourological procedures.

The philosophy of this NATO Advanced Research Workshop and the monograph it has yielded is that if you put a small number of very talented and creative scientists of different backgrounds and documented accomplishments together in a cloistered place for a few days to consider a very important and timely topic, many new ideas will be generated. The keynote of this conference was the Future. By this we mean the expected future developments of highly reliable sequential quantitative measurements of atherosclerotic plaque size and components in living human subjects. Some of the best minds and the most experienced and talented individuals at the leading edges of imaging of arteries were involved; some of the best scientists and students of the atherosclerotic plaque and its components participated; and some of the leading investigators of the cell biology or, as we call it in the USA, the pathobiology of atherosclerosis, contributed important new information. All of these individuals were actively involved in the conference and each obviously had carefully prepared and was able to communicate effectively.

Das Buch enth{lt eine Auswahl der Vortr{ge, die auf dem 15. Dreil{ndertreffen der deutschsprachigen Ultraschallgesellschaften gehalten wurden. Damit informiert es }ber neue technische Entwicklungen und den praktischen Einsatz in den verschiedenen medizinischen Fachgebieten.

The fetal period of human growth and development has become an area of intense study in recent years, due in large part to the development of diagnostic ultrasound. More than 2,000 articles have been published in the last five years describing anatomy and pathology in utero, as reflected in sonographic images. Yet, no stan dard reference exists to correlate these images with fetal gross anatomy and at tempts to draw parallels from adult structure have often led to false assumptions. The dictum "the newborn is not a miniature adult" is all the more valid for the fetus. This text aims to provide a comprehensive reference for normal sectional anat omy correlated with in utero ultrasound images. In addition, magnetic resonance images of therapeutically aborted or stillborn fetuses are paired with similar gross sections to serve as a foundation upon which current in vivo studies may build. Lastly, a miscellaneous section illustrates several anatomic points useful in the understanding of fetal anatomy. These points include the changing anatomy of the fetal brain during gestation and the anatomy of the meninges, the fetal heart, and ductus venosus. It is our hope that this atlas will provide a clear picture of fetal anatomy, rectify some of the confusion which exists in antenatal diagnosis, and stimulate further interest in fetal development."

The primary purpose of this book is to bridge the gap be tween the practice of clinical medicine and diagnostic radi ology. It is intended primarily for utilization by medical students in training and by nonradiologist physicians. In this world of rapidly expanding knowledge in the many specialties of medicine, it is becoming increasingly difficult for many physicians to stay abreast of the newer and constantly changing modalities of diagnosis as well as the therapeutic regimens of the common as well as the less common disease processes within their realm of practice. This book will enable the busy clinician to utilize the consultative services offered by his or her colleagues in diagnostic radiology with maximum effectiveness. The most common clinical applications of the more recent imag ing modalities (i. e. , nuclear medicine, ultrasound, comput erized tomography, and magnetic resonance imaging) have been categorized and condensed into a format that will be both comprehensible and useful on a daily basis for those physicians routinely requesting these diagnostic examina tions for their patients. For simplicity, the book is divided, whenever feasible, into organ systems and subdivided into the multiple classifications of pathologic states (i. e. , con genital, trauma or iatrogenic, inflammatory, and neo plasm). In addition, there are brief comments related to the vii specific advantages and disadvantages as well as the cost effectiveness of each modality.

Twenty years ago, the enzyme superoxide dismutase which uses the superoxide radical anion as its specific substrate was reported. With this discovery was born a new scientific field, in which oxygen, necessary for aerobi c 1 ife on thi s planet, had to be cons i dered also in terms of its toxicity and stresses. This stimulated the search for knowledge of active oxygen species in biology and medicine. Superoxide and other reactive oxygen species are now implicated in many disease processes. Major advances have been achieved during these past years with respect to free radical generation and mechanisms of free radical action in causing tissue injury. In parallel, the possibil ity of influencing free radical related disease processes by antioxidant treatment was studied in various in vitro and in vivo systems. This was the unique theme of a conference organized in Paris by the Society for Free Radical Research (December 9-10, 1988) which brought together experts from basic sciences and clinicians in order to evaluate the current status of antioxidant therapy. The conference emphasized fundamental processes in antioxidant action. Among the major topics were superoxide dismutase (SOD) and low molecular weight substances with such activity, called SOD mimics. Other antioxidant enzymes were also considered. Antioxidant vitamins, in particular vitamins E and C, other naturally occurri ng antioxidants and vari ous synthet i c antioxidants were included in the presentations as there is now a rapidly developing series of compounds with potentially interesting clinical applications.

The first edition of this definitive text ran to 24 chapters. The second edition, reflecting the explosive growth of interest in echo-enhancement, contains 44. The first section deals with some of the most important emerging issues and technologies and covers harmonic imaging, the use of echo-enhancers to provide quantitative information, and the application of enhanced power Doppler to tissue imaging. The second, on contrast echocardiography, explores the use of echo-enhancement during transesophageal imaging. One chapter describes the use of contrast-enhancement transesophageal imaging to determine coronary flow reserve and another gives a detailed account of the application of the technique to the evaluation of left ventricular function. Other authors describe the intraoperative use of contrast echocardiography and discuss the potential of myocardial contrast echocardiography to replace thallium scintigraphy. Another chapter covers the emerging technique of transient response imaging and its role in the assessment of myocardial perfusion, and two chapters are devoted to three-dimensional contrast echocardiographic assessment of myocardial perfusion. Use of echo-enhancement in the evaluation of peripheral circulation is discussed in chapters on carotid and peripheral arterial flow imaging and others that describe renal and hepatic vascular imaging. The newer applications of echo-enhancement outside the cardiovascular system are described in three chapters devoted to the visualization of tumour vasculature. The final chapters look to the future and cover the imaging of intramyocardial vasculature, the development of site-specific agents and the emergence of the new acoustically active agents.

Echo-encephalography, introduced by LEKS ELL in 1955, has gained increasing importance for the early detection of numerous intracranial lesions in the last decade. The main advantage of this diagnostic procedure lies in the fact that it permits a rapid orientation about the spatial relationships within the skull without stressing or endangering the patient. Although this method alone only rarely allows a complete diagnosis, the echo-encephalographic findings always indicate which further diagnostic measures are most suitable for establishing the diagnosis with the greatest accuracy in every case. However, the correct interpretation of an echo-encephalogram is possible only, if the findings which are assumed to be pathological are evaluated in the light of the clinical symptomatology. Since JEPPSSON'S excellent monograph on the origin of the midline echo and its importance for the diagnosis of intracranial expansivities, published in 1961, a great deal of work has gone into the development of echo-encephalography all over the world. For this reason the possibilities of this procedure today go far beyond the mere demonstration of a supratentorial shift. Now we can frequently outline the width of the ventricles exactly and localize tumors or hematomas by means of abnormal reflections. Since a detailed description of the technique, application and present-day diagnostic uses of echo-encephalography has not been available as yet, we undertook to fill this gap in the German literature in 1967 with a monograph summarizing the hitherto existing experience as well as our own extensive case mate rial.

The investigation of the brain by means of ultrasound has acquired increasing importance in the last years because it permits insight into the spatial relationships within the intact human skull in a short time without endangering the patient. The road from the first ultra sonic investigations on the exposed brain to the detection of intracranial midline shifts on the intact skull, the registration of echo pulsations and recently, to ultrasonotomography has been a long one already. However, this development is by no means at an end. Following the suggestion of numerous colleagues concerned with echo-encephalography in this country and abroad, the Neurosurgical Clinic of the University of Erlangen-Nuremberg organized an "International Symposium on Echo-Encephalography" on April 14th and 15th, 1967. Here there was an open exchange of experience on the results obtained up to the present. The limitations of the method and sources of error as well as the directions of future development of the ultrasonic echo procedure were discussed."

Marking the 200th National Meeting of the American Chemical Society, The Division of Nuclear Chemistry and Technology hosted a group of about 90 scientists from 15 different countries to discuss the new trends in radiopharmaceutical synthesis, quality assurance and regulatory control. This event took place in Washington, D.C. on August 27-30, 1990. When I first suggested the idea for this symposium, a group of scientists who pioneered the proposed topics offered their help to organize and run such a big task with me. Their names are listed here in appreciation. Thomas E. Boothe Cyclotron Facility, Mt. Sinai Medical Center, Miami Beach, Florida, USA Robert F. Dannals Division of Nuclear Medicine, The Johns Hopkins Medical Institutions, Baltimore, Maryland, USA Anthony L. Feliu Julich Nuclear Research Center, Julich, Germany Joanna S. Fowler Chemistry Department, Brookhaven National Laboratory, Upton, New York, USA George W. Kabalka Department of Chemistry, University of Tennessee, Knoxville, Tennessee, USA Hank F. Kung Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA James F. Lamb Imagents, Inc., Houston, Texas, USA Harold A. O'Brien, Jr. Los Alamos National Laboratory, Los Alamos, New Mexico, USA Joseph R. Peterson Dept. of Chemistry, University of Tennessee, Knoxville, Tennessee, USA Hernan Vera Ruiz International Atomic Energy Agency, Vienna, Austria Roy S. Tilbury University of Texas, M. D. Anderson Cancer Center, Houston, Texas, USA In addition, a number of distinguished colleagues have participated in the process of reviewing the manuscripts presented in this volume. Their effort is sincerely acknowledged.

Since the pioneering work of Donald and his first Lancet paper in 1958, the use of ultrasound in obstetrics and gynaecology has evolved rap idly. The introduction of grey scale techniques enhanced our ability to identify different tissues on the basis of their texture. However, it was the introduction of the linear array real-time scanner in the mid seven ties that changed ultrasound from being an "eccentric art form" to a readily available and usable technique. This led to the first reports of the diagnosis of neural tube defects using ultrasound by Campbell, as well as the establishment of fetal biometry. In the midst of this activity the parallel development of the transvaginal probe by Kratochwill went almost unnoticed by most gynaecologists. Yet the application of this technique has since had a major impact on many areas of gyna ecological practice, and on infertility in particular. Since the demon stration of transvaginal follicle aspiration, the vaginal route has become standard for most invasive ultrasound guided gynaecological procedures. The relatively new technical advance of transvaginal colour Doppler may potentially have just as great an impact. The introduction and use of transvaginal colour flow imaging has facili tated the study of vascular changes within the pelvis.

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."

Alfons Staudach has been a long-time member of the Anatomic Institute of Karl Franzens University in Graz, where he has devoted particular atten tion to the deeper understanding, appreciation and visualizion of gross ana tomic details. In this work the author has achieved correspondence between sonograms and anatomic sections with a consistency and persuasiveness unequaled in all the previous literature on diagnostic ultrasound. The various planes of section andtheir characteristic features, and indeed the entire format of the text, are designed to provide even the less experienced sonographer with a valuable basis for conducting his examinations. The more experienced reader will find essential information on topographic relations and organ development that is not available in any other work dealing with fetal ana to y. I am certain that my high estimation of this volume will prove justified, and that it will provice its readers with a useful and stimulating resource. Univ. -Prof. Dr. Walter Thiel (Chairman of the Anatomic Institute of the University of Graz) Foreword Anyone setting this book down after an initial perusal must wonder why such a reference was not available ten years ago. The meticulous and fas cinating juxtaposition of gross anatomic sections with sonograms, together with explanatory drawings and many practical guidelines, should enable even the novice accurately to identify details and interpret sonographic findings with precision."

Technical improvements over the past twenty years have made endos copy the procedure of choice for examination of the hollow organs of the genitourinary and gastrointestinal tracts. The development of electro surgical techniques, laser technology, injection therapy, and a wide variety of other modalities now allow the endoscopist to treat many problems that in the past required open surgery. The simultaneous development of transcutaneous abdominal sonography has had an equally dramatic impact on the practice of gastrointestinal and geni tourinary surgery. The marriage of these proven technologies, known as endoscopic sonography, provides an exciting new modality that promises to further revolutionize the diagnosis and management of many intraabdominal diseases. Endoscopic sonography opens new frontiers by overcoming the primary limitations of its parent technologies. Fiberoptic endoscopy is limited by the inability to see beyond the luminal surface, this is particularly important when considering neoplastic disease because depth of wall invasion is a key factor in determining treatment. The limiting factor in transcutaneous sonography is the distance between the transducer and the target organ. With endoscopic sonography, the transducer is placed in close proximity to the target organ. This allows the use of high frequency waves (greater than 5 MHz), which provide better tissue resolution and eliminates the image distortion caused by overlying structures.

Since the beginnings of diagnostic ultrasound in the 1950s, each decade has seen significant advances in this technology. Commer cialization of ultrasound occurred during the 1960s with the introduction of many of the clinical uses that are in existence today. The 1970s showed the most dramatic changes with the commercial introduction of gray-scale and real-time ultrasound. In the 1980s many new advances were introduced, including color Doppler, as well as a wide variety of endoluminal approaches, including endorectal, endovaginal and transesophageal. The decade of the 1990s promises even more significant advances with further transducer miniaturization, three-dimensional ultra sound, and the introduction of a variety of ultrasound contrast agents. With such rapid changes occurring, it becomes important to disseminate knowledge in as rapid a fashion as possible, thus it was quite appropriate that a meeting such as this be held to provide an in-depth review of the many new areas of ultrasound imaging that show promise for the future. Emphasis was on the new uses of ultrasound in gastrointestinal diseases. Many of these advances will, of course, also have applications in many other areas of the body. It is hoped that those in attendance will acquire a much broader understanding of where ultrasound is now and where it is headed in the not too distant future.

Only a few years ago, most treatises on sonography covered all the diagnostic applications of ultrasound, de scribing organs from the brain down to the placenta. Dr. Bruneton and his associates must be thanked for pre senting this book devoted to the spleen. It probably offers the most complete presentation of details and the richest images available in its field. This book will thus become the ultimate reference in most libraries of books on son ography. March 1988 F. Weill The authors wish to thank Christine Rostagni, Fran ise Fein, and Bernard Fontaine for their assistance in the preparation of this book. Contents 1 Sonographic Anatomy of the Normal Spleen, Normal Anatomic Variants, and Pitfalls B. Senecail . . . . . . . . . . . . . . . . . . . . . . 1 1. 1 Anatomy of the Spleen. . . . . . . . . . . . . . . . 1 1. 1. 1 Morphology and Structure . . . . . . . . . . . . . 1 1. 1. 2 Location and Relations of the Spleen. . . . . . . . 3 1. 1. 3 Average Dimensions of the Cadaver Spleen . . . . 5 1. 1. 4 Congenital Anomalies and Normal Variants. . . . 5 1. 1. 4. 1 Fissured Spleen. . . . . . . . . . . . . . . . . . . . 5 1. 1. 4. 2 Lobulated Spleen. . . . . . . . . . . . . . . . . . . 5 1. 1. 4. 3 Spleen with Two Hili. . . . . . . . . . . . . . . . . 5 1. 1. 4. 4 Wandering or Ectopic Spleen . . . . . . . . . . . . 6 1. 1. 4. 5 Numeric Anomalies . . . . . . . . . . . . . . . . . 6 Ultrasonography of the Spleen . . . . . . . . . . . 1. 2 6 1. 2. 1 Equipment . . . . . . . . . . . . . . . . . . . . . . 6 1. 2. 2 Patient Examination . . . . . . . . . . . . . . . . . 7 1. 2. 3 Scanning Technique . . . . . . . . . . . . . . . . . 7 1. 3 Sonographic Features of the Normal Spleen. . . . 7 1. 3. 1 Splenic Contour . . . . . . . . . . . . . . . . . . . 7 1. 3. 2 Echo Pattern of the Splenic Parenchyma. . . . . ."

This book constitutes the Proceedings of the 26th Symposium on Acoustical Imaging held inWindsor, Ontario, Canada during September 9-12, 2001. This traditional scientific event is recognized as a premier forum for the presentation of advanced research results in both theoretical and experimental development. The lAIS was conceived at a 1967Acoustical Holography meeting in the USA. Since then, these traditional symposia provide an opportunity for specialists who are working in this area to make new acquaintances, renew old friendships and present recent results of their research. Our Symposium has grown significantly in size due to a broad interest in various topics and to the quality of the presentations. For the firsttime in 40 years, the IAIS was held in the province of Ontario in Windsor, Canada's Automotive Capital and City of Roses. The 26th IAIS attracted over 100specialists from 13countries representing this interdisciplinary field in physical acoustics, image processing, applied mathematics, solid-state physics, biology and medicine, industrial applications and quality control technologies. The 26th lAIS was organized in the traditional way with only one addition-a Special Session "History of Acoustical Imaging" with the involvement of such well known scientists as Andrew Briggs, Noriyoshi Chubachi, Robert Green Jr., Joie Jones, Kenneth Erikson, and Bernhard Tittmann. Many of these speakers are well known scientists in their fields and we would like to thank them for making this session extremely successful.

Congenital hip dysplasia and dislocation are common diseases of newborns and small infants, with frequently severe consequences if orthopaedic therapy is not initiated at an early stage. Therefore many clinicians have been looking for a simple method for the investigation of the hip joint in the early neonatal period. Up to 1980 the diagnosis of hip dysplasia could usually not be made before the 3rd month of life, by means of pelvic roentgenography. Only incomplete or complete unilateral dislocations were diagnosed in the neonatal age group. In 1980, however, Graf, an Austrian orthopaedic surgeon, began using ultrasound investigation ofthe hip joint in newborns and small infants in order to make an early diagnosis and to avoid radiation exposure. The intention of the present study was to compare ultrasound of the hip joint with other established diagnostic procedures and to establish whether it is suitable as a screening procedure in newborns. 2 Incidence of Congenital Hip Dysplasia and Dislocation In 1972 Barlow reported that 90 % of hips which are unstable at birth develop to normal joints spontaneously without any therapy. Visser (1984) thus suggested determining the percentage of hip dislocations after the 2nd - 3rd month of life so that children with spontaneous stabilisation would be excluded.

It will be a long time before the quality of this profusely illustrated book is overtaken and the present spate of books on the subject of obstetric ultrasound may, as a result, suffer a numerical set-back - especially with translation into English which will "deliver the milk on everyone's doorstep". Two of the authors studied in our department in Glasgow and worked like If there are any rewards for teaching, then we humble Scots who demons. have had the privilege have had more than our share as a result of the pride with which we regard our pupils. In my own old age and looking back over the last thirty years, the innumer able difficulties, set-backs and disappointments have been more than compen sated for by those who have turned the subject from a laughable eccentricity (as I have at one time experienced) into a science of increasing exactitude. This transformation has come about, not by any efforts of mine, but by the enthusiasm and ingenuity of those who would probably have achieved as much on their own if given the encouragement which I ultimately received in Glasgow University life. Limbo must be the expected lot of most of us ordinary mortals but the work lives on. And so, in this reminiscent and philosophical mood I beg leave to quote a little poem which I wrote at an age when young men do that sort of thing.

Medical applications of ultrasound range from therapy, foetal monitoring, diagnostic imaging and blood flow measurement, to surgery and lithotripsy. Ever since the earliest developments of medical ultrasound there has been an interest in the measurement and characterisation of the ultrasonic fields generated in these applications, either for assessment of performance of equipment or for safety. Until recently, procedures for acoustic output measurements were ill-defined, but standards are now being developed internationally by the International Electrotechnical Commission (1EC) and reliable commercial measuring equipment is becoming more widely available. The aim of this book is to introduce acoustic output measurement techniques and to provide an insight into the measurement methods. The material presented is based on a course originally run during November 1989 at the National Physical Laboratory. In addition to the lectures, the course consisted of a series of practicals to allow participants to gain experience of making measurements. Teddington, UK Roy C. Preston February 1991 Contents List of Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii List of Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1 Safety of Diagnostic Ultrasonic Equipment: The Relevance of Acoustic Output Information to the Clinical User R. C. Preston 1. 1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1. 2 The Relevance of Acoustic Output Information. . . . . . . . . . . . . 6 1. 2. 1 What Is Acoustic Output Information? . . . . . . . . . . . . . . . . . . . 6 1. 2. 2 What Is Acoustic Output Information Used For? . . . . . . . 6 1. 2. 3 Why Should You Know the Acoustic Output Levels of Your Equipment? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1. 2. 4 Are Acoustic Output Levels Really that Important? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Dr. Jean Lintermans came to Seattle in 1962 from his general pediatric residency at the University of Iowa. He worked with us in clinical pediatric cardiology and in our animal physiology laboratory for the next three years. He was the most productive individual in the history of our training program, publishing seven papers in those three years, four clinical papers and three involving pulsed ultrasonic flowmeters and implanted ultrasonic displacement devices in animals. The work, from laboratory to publication, was always done with the utmost attention to accuracy, and was well developed conceptually. Although English was not his native language, Jean's mastery of English was not only excellent, I felt that he actually communicated better than many of our native physicians. During the past year, I was delighted to learn that Jean was preparing a textbook on pediatric echocardiography with Dr. van Dorp, and was even more pleased to be asked to write a foreword .. However, the greatest pleasure came from actually reading this book, and finding that it does indeed have a unique approach, and with the additional genuine benefit to the reader of a thorough, consistent, segmental approach to the diagnosis of congenital heart disease.

It is now more than 40 years since Drs. Wild and Reid published their first experience with rectal ultrasonography from the Surgery Department at the University of Minnesota. Professor Owen H. Wangen steen, in whose laboratory the studies were carried out, recognized at that time the need for early detection in the treatment of cancer. Technical improvements over the past 20 years have made endoscopy the procedure of choice for examination of the hollow organs of the genital, urinary and gastrointestinal tracts. The simultaneous development of endosonography has had an equally dramatic impact on the practice of medicine and surgery. The technology has been demonstrated to be helpful in both benign and malignant conditions. One of the so-called benign conditions of the anorectum is fistula-in-ano. Fistula surgery has always relied on excellent anatomic delineation of the intramuscular tracts. There is hope that adaptation of ultrasonographic technology will aid in the surgical management of this malady. Clearly, rectal ultrasonography has considerable potential in the management of rectal carcinoma. Accuracy rates in the range of 90% for the depth of neoplastic invasion have been reported. This ability for accurate assessment will undoubtedly lead to a better definition of the population of patients that can be managed by local therapeutic means.

Avascular Necrosis (AVN) is a disease resulting from temporary or permanent loss of blood supply. It frequently affects the femoral head and in this area, if left untreated, routinely causes premature joint destruction.

In the USA, 5 to 10% of cases of hip osteoarthritis requiring total hip replacement are primarily caused by AVN. In 33 to 72% of patients, the disease is bilateral. The peak incidence is between 30 and 60 years of age, and the social costs of this pathology are remarkable. There is therefore increasing interest in hip joint preserving techniques such as conservative treatment through electromagnetic fields and shockwaves as well as joint preserving surgical techniques. This volume aims to present a complete overview of the current knowledge on AVN including therapeutic options.