Detection nonlinearity from micro-bubble contrast agents

The pulse inversion Doppler technique is applied for detecting ultrasound contrast agents through their nonlinear behavior. The linear and nonlinear scattering from the tissue can be separated from the Doppler spectrum. It is shown that this technique improves the agent-to-tissue contrast by 3 to 10 dB as compared with the harmonic technique. A factor up to 16 dB in contrast gained can be achieved when compared with the broadband conventional Doppler technique. Contrast improvement is thus made possible for imaging of blood flow in microvasculature with high clutter tissues.