Intracoronary and, more recently, intravenous injection of a contrast medium renders it possible to determine myocardial perfusion by use of ultrasound. For the analysis of the data obtained with two-dimensional phased array echocardiographic equipment, two methods can be carried out. First, in the off-line method, the images stored on video tape can be transferred to a computer memory by use of a frame grabber, after which computer analysis of the data can be performed. Second, the phased-array electronics can be directly connected to a computer. In this setup the computer controls the phased array, and the data transported consists of the high-frequency signal. Both methods are described. Some advantages of high-frequency measurements over video-densitometry are the independence of the setup of the two dimensional machine and the higher signal-to-noise ratio. Furthermore, there is the possibility to use the amplitude, phase, and frequency of the high-frequency signal. In this way a detailed study of the contrast medium is possible and the analysis can also be performed for the purpose of a combination with other methods, such as tissue identification.