Every few years a dissertation comes to the area of clinical
application of medical technology which carries us forward as on a
magic carpet into new regions of understanding and patient care.
This book is such a magic carpet. It brings together, in a clear
and incisive fashion, important hemodynamic principles with a
simple noninvasive method of application to a part of the cerebral
vasculature which has been relatively inaccessible. To the lucky
and perceptive person who reads this book, a feeling of excitement
and hope for progress is engendered. The diligent application of
the potentials of transcranial Doppler ultrasound brings new power
to our efforts in understanding the cerebral circulation and the
causes, treatment and prevention of cerebrovascular disorders.
Merrill P. Spencer, M. D. Director Institute of Applied Physiology
and Medicine Seattle, Wash. , July 1986 Acknowledgements I am
greatly indebted to Prof. He1ge Nornes, Oslo, who introduced me to
the fascinating study of cerebral hemodynamics in the early 1970's
and since then continually encouraged my interest in this field. It
was through his pioneering work on the cerebral circulation-using
peroperative electromagnetic flowmetry and Doppler techniques-that
the basis was laid for the noninvasive trans cranial approach to
the circle of Willis described in this book. I also gratefully
acknowledge the stimulating case discussions with Prof. Peter
Huber, Berne, at the very early introduction of trans cranial
Doppler, the inspiring exchange of ideas with Dr. Merrill P.