Transcranial Doppler Ultrasonography. Edited by viken l babikianand lawrence r wechsier. (Pp 409, £100.00). Published By Butterworth Heinemann, Oxford, 1999. ISBN0 7506 9969 8. In the 17 years since Aaslid's first description of transcranial Doppler ultrasonography (TCD) the technique has developed from a research tool to a routine clinical investigation, at least in some circumstances. This transition has been especially rapid in the 6 years since the first edition of this book was published in 1993. This second edition has grown in volume by 180 pages and now comprises 24 chapters organised into sections covering basic techniques and physics of Doppler ultrasound, cerebrovascular physiology, evaluation of cerebrovascular disease, monitoring for microemboli, intraoperative and intensive care monitoring, transcranial duplex imaging, paediatric applications, …