The NATO Advanced Study Institute (ASI) on Physics and Engineering of Medical Imaging has addressed a subject which in the wide area of biomedical technology is one of those which are showing greater impact in the practice of medicine for the ability to picture both Anatomy and Physiology. The information and accuracy obtained by whatever imaging methodology is a complex result of a multidisciplinary effort of several sciences such as Physics, Engineering, Electronics, Chemistry, Medicine, etc ... Development has occurred through work performed in different environments such as basic and applied research laboratories, industries and clinical centers, with the aim of achieving an efficient transfer of know-how and technology for the improvement of both investigation possibilities and health care. On one hand, such an effort requires an ever-increasing committment of human and financial resources at research and industrial level, and, on the other, it meets serious difficulties in recruiting the necessary human expertise oriented to this technology which breaks with the tradi tiona I academic borders of the single disciplines. Furthermore, the scientific community is continually dealing with the problem of increasing the performance and, at the same time, complexity and costs of instruments, applying more and more sophisticated technology in an effort to meet the demand for more complete and accurate clinical information. The scientific program of this ASI and the qualification of the authors reveals the intrinsic complexity of the development process of the Imaging methodologies.