Abstract: The contrast-to-tissue ratio is improved while imaging contrast infused tissue. A subject is infused with contrast medium having microbubbles at a fundamental frequency. First and second transmit pulses are transmitted into the subject. The first and second transmit pulses each comprise first, or basic, and second, or seed, signals. The basic signal has a frequency based on the fundamental frequency and the seed signal has a subharmonic frequency based on the frequency of the basic signal. The first and second transmit pulses are phase inverted with respect to each other. Received echoes from first and second transmit pulses are filtered at a subharmonic or ultraharmonic frequency to remove tissue response and pass microbubble response.

Abstract: The contrast-to-tissue ratio is improved while imaging contrast infused tissue. A subject is infused with contrast medium having microbubbles at a fundamental frequency. First and second transmit pulses are transmitted into the subject. The first and second transmit pulses each comprise first, or basic, and second, or seed, signals. The basic signal has a frequency based on the fundamental frequency and the seed signal has a subharmonic frequency based on the frequency of the basic signal. The first and second transmit pulses are phase inverted with respect to each other. Received echoes from first and second transmit pulses are filtered at a subharmonic or ultraharmonic frequency to remove tissue response and pass microbubble response.