This is the first book to present an overview of the exciting new cardiac imaging technique of tissue Doppler echocardiography (TDE). In order to understand the background of this technique, it is necessary to compare the physical properties of blood, which reflects ultrasound poorly but moves with high velocity (up to 150 cm/s) with those of the myocar­ dium, which reflects ultrasound strongly but moves with low velocity (less than 10 cm/s). In tissue Doppler imaging, existing Doppler technology has been modified to bypass the high-pass filter and enhance calculation of low velocities, thus enabling selective visualization of the myocardium rather than of the blood. Because the color Doppler tissue images are super­ imposed on the conventional two-dimensional ultrasound images, this technique is known as TDE. Following a brief introduction, the history of ultrasound and Doppler imaging is presented. It is now about 150 years since the death of Christian Doppler, who described the "Doppler" effect, and more than 100 years since Pierre Curie discovered the piezoelectric effects of crystals. TDE was developed by Nobuo Yamazaki and Yoshitaka Mine at the Medi­ cal Engineering Laboratory, Toshiba Corporation, Tochigi, Japan. En­ gineers involved in the development of the technique have provided important technical information, which the reader will find an invaluable background to potential applications ofTDE.