A novel signal processing and imaging method for ultrasonic molecular imaging

We have recently developed an ultrasonic targeted imaging technique by taking advantage of wideband transient high frequency acoustic emission from ultrasound contrast agents. The imaging sequence includes a B-mode imaging pulse sequence in which a short pulse is transmitted with the outer low frequency arrays and received with the inner high frequency array (TLRH: transmit at low frequency and receive at high frequency), followed by a long radiation force pulse to induce immediate bubble adhesion using the center array, and a second B-mode imaging pulse sequence. The RF data obtained from the second B-mode pulse sequence is averaged and then subtracted by that from the first B-mode sequence. The imaging technique was tested in a targeted imaging phantom, where lipid-shelled biotin microbubbles flow within an avidin coated-cellulose. Results showed that tissue signals were suppressed up to 33 dB and a targeted bubble contrast-to-free bubble signal ratio of up to 23 dB was obtained from the composite sequence imaging.