The first edition of this book was well received by readers and reviewers and we are very grateful for the positive reactions. We were convinced then, and even more now, that MRI and MRS have much to offer in diagnosis, therapy monitoring and research of hereditary and acquired myelin disorders. In the last few years, a great deal of new information has come available, concern ing the genetic basis of inborn errors of metabolism and neurodegenerative disor ders, the role of subcellular structures, the enzyme biochemistry, the pathophysio logical mechanisms of posthypoxic-ischemic cerebral damage, and the inflammato ry processes in infectious and inflammatory disorders. MR images of many rare disorders have become available, either in our own experience or published by other groups. MR spectroscopy could confirm its role in certain clinical applica tions. Because of these developments, it was necessary for us to rewrite the book almost completely. In some fields developments are so fast that we may not have caught all the latest developments. The pattern of the new approaches has, however, been established, making the assimilation of newly available information easy. We are extremely grateful for the help of colleagues to make this book as com plete as possible. The positive reactions of those from whom we requested MR pictures or other forms of support were of enormous encouragement to us during our efforts to complete this project. We hope this work will be as warmly welcomed by our colleagues as the first edition.