This volume brings together the papers which 33 radiologists, chosen among the leading European experts, presented at the Halley Project 1996 Refresher Course. The project, which I promoted and co-ordinated, started out under the aegis of the European Association of Radiology in 1992 with the aim of fostering the advancement of Radiology in various countries of Eastern Europe: Bulgaria, the Czech Republic, Slovakia, Hungary, Poland and Rumania. Thanks to the expertise and enthusiasm of distinguished colleagues from various countries in Western Europe and to the generosity of two sponsors, Bracco International and Schering A.G., it was possible to set up, in 1992, 1993, 1994 and 1995. four Faculties of Experts in Uroradiology. Gastrointestinal and Abdominal Radiology, Chest Radiology and Skeletal Radiology. These four faculties then gave a refresher course on the four radiological subspecialities in the six nations mentioned above. The project was called Halley, after the famous comet, in a desire to express the idea of spreading Western radiological culture among Eastern radiologists who were visited in their own countries. In these 4 years. as project leader, I accompanied the four Faculties during their tour and was thus able to experience the various local situations, not only in radiological terms but also socially. thanks to the ever warm relationships among radiologists of different nationalities and of different ages who attended the courses.