Prior to the virtual atomic explosion of medical knowledge, at a time when communication was very much slower, a medical book, to be authoritative and believable, had to be written by a very knowledgable, and, per force, usually quite senior person. The choice of texts was limited and tended to be dominated by a few "classic" (a phrase not quite synonymous with dogma). Following the information explosion, the scenario is quite different. Not only is there a geometric progression in the quantity and speed of development of new medical knowledge, but also this development is occurring at very dif­ ferent rates in different countries. This is particularly true in medical imaging. The result is that it is now virtually impossible to produce a "single author" book that can cover the field or even a subdivi­ sion of it. This absolute requirement for multiple authors has in turn created the need for a new type of editor/author who must be multinational in approach, have a uniquely informed appreciation of what is going on in medical imaging research throughout the entire world and possess the depth of personal knowledge and experience to judge cor­ rectly what work is the most rigorous and likely to have the greatest impact.