Over 10 years have passed since the first edition of The Mediastinum was published in 1977. I have been very gratified by the response to the first edition and determined to do a second edition as soon as possible. However, good intentions are sometimes difficult to achieve and a decade has passed. This period has been one of enormous growth in the discipline of diagnostic imaging. In the study of the mediastinum, computed tomog­ raphy, and more recently magnetic resonance, have revolutionized our diagnostic capabilities. This second edition of the mediastinum is in­ tended to emphasize the importance of these modalities to the evalua­ tion of mediastinal disease. In addition, an attempt will be made to integrate into the text the many new and important observations relat­ ing to all aspects of mediastinal imaging which have appeared in the literature since 1977. The overall emphasis, however, will remain the same: that accurate radiologic diagnosis is based upon a thorough understanding of corre­ lated radiographic anatomy and pathology. No matter what the imag­ ing modality, this principle remains fundamental to each and every radiographic interpretation. I would like to express once again my deep appreciation to Dr. Stephen A. Kieffer, Chairman of the Department of Radiology at the State University of New York Health Science Center at Syracuse for his continued support and encouragement.