High-resolution clinical systems operating near 15 MHz are becoming more available; however, they lack sensitive harmonic imaging modes for ultrasound contrast agent (UCA) detection, primarily due to limited band-width. When an UCA is driven to nonlinear oscillation, a very wideband acoustic transient response is produced that extends beyond 15 MHz. We propose a novel strategy using two separate transducers at widely separated frequencies and arranged confocally to simultaneously excite and receive acoustic transients from UCAs. Experiments were performed to demonstrate that this new mode shows similar resolution, higher echo amplitudes, and greatly reduced attenuation compared to transmission at a higher frequency, and superior resolution compared to transmission and reception at a lower frequency. The proposed method is shown to resolve two 200 μm tubes with centers separated by 400 μm. Strong acoustic transients were detected for rarefaction-first 1-cycle pulses with peak-negative pressures above 300 kPa. The results of this work may lead to uses in flow and/or targeted imaging in applications requiring very high sensitivity to contrast agents.
|Original language||English (US)|
|Number of pages||10|
|Journal||IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control|
|State||Published - Aug 2005|
ASJC Scopus subject areas
- Electrical and Electronic Engineering
- Acoustics and Ultrasonics