Second harmonic Doppler ultrasound blood perfusion measurement

In vivo testing of a recently introduced method of evaluating blood perfusion is presented, where the Doppler shift of the second harmonic component of the backscattered echo is measured. Central to this measurement is the administration of a galactose-based contrast agent which has been shown in vitro to exhibit extraordinary nonlinear backscattering properties. In vivo studies on living rabbits are described, in which blood perfusion is manipulated by various mechanisms to obtain some indication of the quantitative ability of the measurement. It is shown that use of the second harmonic measurement results in a greatly superior ratio of blood echo intensity to tissue echo intensity, allowing real-time determination of blood volume fluctuations in tissue