High-frequency (>10 MHz) ultrasound is used in, e.g., small animal imaging or intravascular applications. Currently available ultrasound contrast agents (UCAs) have a suboptimal response for high frequencies. This study therefore investigates the nonlinear propagation effects in a high-frequency ultrasound field (25 MHz) and its use for standard UCA and diagnostic frequencies (1-3 MHz). Nonlinear mixing of two high-frequency carrier waves produces a low-frequency wave, known as the self-demodulation or parametric array effect. Hydrophone experiments showed that the self-demodulated field of a focused 25 MHz transducer (850 kPa source pressure) has an amplitude of 45 kPa at 1.5 MHz in water. Such pressure level is sufficient for UCA excitation. Experimental values are confirmed by numerical simulations using the Khokhlov-Zabolotskaya-Kuznetsov equation on a spatially convergent grid.

Additional Metadata
Persistent URL dx.doi.org/10.1121/1.3298436, hdl.handle.net/1765/32740
Citation
Vos, H.J., Goertz, D.E., & de Jong, N.. (2010). Self-demodulation of high-frequency ultrasound. Journal of the Acoustical Society of America, 127(3), 1208–1217. doi:10.1121/1.3298436