Time-domain ultrasonic contrast blood flowmetry

Time-domain ultrasonic blood flow estimation methods have recently received considerable attention because of their advantages over conventional Doppler methods. Among them are that they may yield better spatial resolution and that methods based on frame-to-frame speckle tracking do not require a knowledge of the angle between directions of blood flow and the ultrasound beam. These methods, however, suffer from an intrinsic problem of poor signal-to-noise ratio, since the echoes scattered back by blood are much weaker than those of the surrounding structures. In addition, the maximal velocity that can be estimated by frame-to-frame tracking via conventional ultrasonic scanners is limited by the frame rate of the scanner. In this article, we will present experimental results to show that these problems may be alleviated by using a high frame rate scanner in conjunction with the injection of an ultrasonic contrast agent. In this study the contrast agent used was Albunex.