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I am particularly pleased to be able to write the introduction to this book that resulted from a collaborative effort by the Radiology De­ partment, under the auspices of the Boerhaave Committee for Postgraduate Medical Education of the Faculty of Medicine, at the University of Leiden and the Department of Medical Imaging and Radiological Sciences at Van­ derbilt University. Magnetic resonance imaging affords the opportunity to interrogate organ and system structure and function in a nondestructive manner without se­ rious biological implications. Tissue contrast with this modality is ex­ quisite and inherently superior to that of x-ray computed tomography. The advances to improve signal capture, development of rapid data acquisition techniques, fabrication of more appropriate pulse sequences, and availa­ bility of contrast agents portend increased versatility and specificity of these studies. Despite the proliferation of numerous general and specialized texts, the developments in MRI occur at such a pace that data in these references are necessarily dated. The technical horizon of MRI is vast with almost li­ mitless possibilities of signal generation and plan reconstruction. Tissue contrast is so importantly affected by the coupling of signal generation and capture that collective experience of institutions and investigators is extremely important to the initiate and useful even to those indivi­ duals with the greatest clinical experience.

Recent years have witnessed dramatic advances in the development and use of magnetic resonance imaging (MRI) techniques that can provide quantitative measures with some degree of pathological specificity for the heterogeneous substrates of multiple sclerosis (MS). Magnetic resonance spectroscopy (MRS) is one of the most promising of these techniques. Thanks to MRS, axonal damage is no longer considered an end-stage phenomenon typical of only the most destructive lesions and the most unfortunate cases, but rather as a major component of the MS pathology of lesions and normal-appearing white matter at all the phases of the disease. This new concept is rapidly changing our understanding of MS pathophysiology and, as a consequence, the therapeutic strategies to modify the disease course favorably. Many of the authors have pionereed the use of MRS in MS, thus contributing to the foundation of the'axonal hypothesis'.

Nuclear magnetic resonance (NMR) is having an enormous liTIpact on biomedical research both at the basic science and clinical levels. In order to appreciate the elegance and power of this technology a historical perspective is in order. In 1924 Pauli suggested that hydrogen nuclei might possess a magnetic IIlOlllent. This was in fact confinned by Rabbi in 1939 who demonstrated that a beam of hydrogen molecules in the presence of a magnetic field could be mutated by radio frequency fields resonating at the Iarmor frequency.'Ihe first successful NMR experiments in condensed matter were independently conducted in late 1945 by Purcell, Torrey and PoUnd and by Bloch, Hansen and Packard.'Ihe Purcell group detected proton NMR in solid paraffin and the Bloch group detected proton in liquid water. Bloch and Purcell received the Nobel Prize in physics in 1952 for these observations. Until about 1952, studies of liquids and solids with broad resonance lines dominated the field of NMR. However, the reports of 3 1 P NMR chemical shifts in several corrpounds in 1949 by Khight, of 14 N resonances in several ions by Proctor and Yu in 1950, and of 1 9 F resonances in several corrpounds in 1950 by Dickinson led to the development of high resolution NMR in Itquids. since the molecular motions in liquids result in very narrow lines compared to those in solids, :much smaller chemical shifts could be detected.

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.

Throughout the twentieth century, interest in sport has evidenced a major increase worldwide and a new field of sports medicine has emerged. Sport spectators hip has been stimulated in part by the increased ease of international travel and the intro­ duction of new means of communication. Interest in professional sports and in such events as the World Cup and the Olympic Garnes has never been higher and the general popularity of sports has drawn increasingly greater numbers of young people to sports participation. Interest in sports participation has been strength­ ened both by the provision of numerous sports facilities to populations throughout the world and the accumulating information base that relates regular participation in programs of sport and exercise to health enhancement. Along with in­ creases in interest and participation has corne a need for a better understanding of the physiological changes accompanying muscular activity and of the trauma that can result from both competitive sport and recreational exercise.

This book has been written for radiologists, ophthalmologists, neurologists, neurosur­ geons, plastic surgeons, and others interested in the evaluation of disorders with ophthalmologic signs and symptoms. It is designed to provide recent knowledge in this area derived from ultrasonography, computed tomography (CT), and magnetic resonance imaging (MRI). In the past decade, the advent of ultrasonography, computed tomography, and more recently magnetic resonance imaging has provided diagnostic images of the eye, orbit, and brain in a fashion that had been a dream of many prior to the develop­ ment of these techniques. These newer modes of diagnosis have replaced some previous techniques, such as nuclear medicine imaging and, to some degree, vascular studies and orbitography. There are three sections to this book. The first section is a discussion of the imaging techniques. The second is devoted to the role of these imaging methods in the evaluation of ophthalmic disorders. The last section, dealing with radiotherapy for ophthalmologic tumors, is included because the current imaging techniques are needed for treatment planning. We wish to thank the many people who have assisted us in preparing this manuscript. Among these are many librarians, secretaries, trainees, and photographers. Weare especially indebted to artist Peter Clark for his illustrations and to Mr. Martin Leibo­ vici, Associate Curator of New York University Medical School and Director of Health Sciences Library of Goldwater Memorial Hospital, New York City. Also, we wish to thank our families for their help and patience.

Primary reconstructive surgery is assuming increasing importance in the management of fractures of the spine. Analysis of the injury and thus surgical decision-making are greatly facilitated by the diagnostic power of CT and MRI. This volume provides a systemic introduction to the interpretation of CT and MRI images of injuries to the spinal column and the spinal cord, with special emphasis on the assessment or residual stability. Since survey X-rays remain the indispensable first step in radiodiagnosis, the typical appearances of spinal injuries on conventional films are also shown. This will help the reader interpret the CT and MRI images and also reflects the procedure in radiologic practice. The book`s classification of spinal fractures, together with the attempt to conclude how the injury happened by analyzing the damage caused, paves the way for individually oriented therapy.