This book has been edited by two of the best known experts in the field of breast diseases. It was in 1975 that MICHAEL FRIEDRICH, Professor of Radiology at the Free University of Berlin, commenced his efforts to develop and improve mammography so as to allow the early diagnosis of breast cancer. The outstanding results that he has achieved have led to awards from the German Radiological Society (the Hermann-Holthusen-Ring) and the Medical High School, Hannover (the Johann-Georg-Zimmermann Prize). EDWARD ALLEN SICKLES, Professor of Radiology and Chief of the Breast Imaging Section at the University of California San Francisco, has since 1976 devoted much effort to comparison of the different methods of diagnostic radiology of the breast, including ultrasonography and magnetic resonance imaging. He has received many distinctions and important awards in recognition of his studies. Professor Sickles is one of the leading radiologists in this field of research in the United States, and is well known all over the world.