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Aberration in nonlinear acoustic wave propagation.
Trond Varslot1, Svein-Erik Måsøy, Tonni F Johansen
1Department of Electrical Computer and Systems Engineering, Rensselaer Polytechnic Institute, Troy, NY, USA. trond@ecse.rpi.edu
Summary
Second-harmonic ultrasound imaging does not resolve ultrasonic wave aberration. Aberration affects the second harmonic similarly to the fundamental frequency, challenging its use for improved medical imaging quality.
Area of Science:
- Medical imaging
- Acoustics
- Biomedical engineering
Background:
- Nonlinear acoustic wave propagation in biological tissue enhances contrast resolution in medical ultrasound imaging.
- Ultrasonic wave aberration and reverberations are major sources of acoustic noise, stemming from tissue property variations near the body surface.
- Second-harmonic imaging is theorized to mitigate these issues by generating the harmonic after the aberrating body wall.
Purpose of the Study:
- To investigate whether second-harmonic ultrasound imaging effectively reduces ultrasonic wave aberration.
- To determine if the second harmonic is generated after the aberrating source, as commonly assumed.
- To compare the aberration experienced by the second harmonic with that of the fundamental frequency.
Main Methods:
- Theoretical analysis of nonlinear acoustic wave propagation.
- Computer simulations of ultrasonic wave propagation and harmonic generation in biological tissues.
- Comparison of aberration effects on first and second harmonic waves.
Main Results:
- Second-harmonic imaging does not solve the problem of ultrasonic wave aberration.
- The second harmonic is generated by an aberrated source, meaning it experiences aberration from the outset.
- Simulations show that the second harmonic experiences aberration comparable to the first harmonic.
Conclusions:
- The assumption that second-harmonic generation occurs after the primary aberration source is flawed.
- Second-harmonic ultrasound imaging does not inherently reduce aberration effects.
- The findings challenge the utility of second-harmonic imaging for overcoming aberration-related noise in medical ultrasound.
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