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NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competences and with regard for appropriate balance.

This report has been reviewed by a group other than the authors according to procedures approved by a Report Review Committee consisting of members of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine.

Support for this project was provided by the Advanced Research Projects Agency, the Department of Energy, and the National Institute of Mental Health.

Library of Congress Catalog Card Number 95-72622
International Standard Book Number 0-309-05387-0

Copyright 1996 by the National Academy of Sciences. All rights reserved.

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Washington, DC 20418
Available on the Internet via the World Wide Web at the URL:
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COVER ILLUSTRATIONS: The upper figure was produced by rapid volumetric magnetic resonance imaging (MRI) after injection of a paramagnetic contrast agent and shows vessel anatomy, kidney perfusion, and ureters (bright). The contrast agent causes urine and blood to produce different magnetic resonance signals. (Illustration courtesy of George Holland, University of Pennsylvania and General Electric Medical Systems.) The lower illustration, an example of modern non-invasive computed tomography (CT), shows calcium deposits in the aorta (center of image) and the blood vessel anatomy. It was produced using rapid data collection via spiral CT with injected contrast material. (Illustration courtesy of Siemens Medical Systems.)