Experimental evaluation of the received signal from blood at 50 MHz

In order to evaluate the received echoes from blood at high frequencies, we present M-mode images as well as a statistical analysis of the in-vitro and in-vivo signal from blood using a short transmitted pulse with a transducer center frequency of 50 MHz. This analysis shows that individual scattering volumes can be tracked in the axial direction. Using both changes in the location and magnitude of the peak of the rf correlation, vessels as small as 100 microns can be visualized in the rf signal and distinguished from stationary targets. The experimental system provides the opportunity to examine changes in flow and in the vessel wall over a cardiac cycle.