Principles of Harmonic Imaging
Ultrasonic contrast agents with microbubbles were originally intended to make use of the difference between the acoustic impedance of gas and that of blood and tissues to obtain strong echo signals. In the case of contrast agents for intravenous administration, microbubbles must pass through the capillaries in the lungs, and therefore can be no larger than about 8 μm in diameter. Because of this limitation, the scattering intensity obtained with these microbubbles is not high enough to visualize blood flow easily by conventional B-mode imaging.
KeywordsContrast Agent Native Tissue Phase Inversion Harmonic Imaging Fundamental Wave
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