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A focused ultrasound method for simultaneous diagnostic and therapeutic applications--a simulation study
E Konofagou1, J Thierman, K Hynynen
1Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
Physics in Medicine and Biology
|November 27, 2001
Summary
Ultrasound-stimulated acoustic emission (USAE) imaging can monitor tissue damage. Higher frequencies enhance USAE response, aiding coagulation monitoring during ultrasound surgery.
Area of Science:
- Medical Imaging
- Biomedical Engineering
- Acoustics
Background:
- Ultrasound surgery requires real-time monitoring of tissue damage.
- Ultrasound-stimulated acoustic emission (USAE) is a potential imaging modality for this purpose.
Purpose of the Study:
- To investigate the influence of tissue stiffness and absorption on USAE response amplitude.
- To determine optimal frequencies for USAE in coagulation monitoring.
Main Methods:
- Simulated uniform lesions in homogeneous media using finite-element analysis.
- Applied high-frequency ultrasound (1.7 MHz) to excite tissue and generated low-frequency radiation force (1-50 kHz).
- Recorded tissue displacement response at various locations to generate images.
Main Results:
- Displacement amplitude decreased with stiffness at lower frequencies but increased at higher frequencies (>22 kHz).
- Absorption increase consistently led to a linear increase in mechanical response amplitude.
- Higher frequencies showed a synergistic effect of stiffness and absorption on tissue response.
Conclusions:
- USAE shows promise for monitoring coagulation during ultrasound surgery.
- Higher frequencies (above 22 kHz) are optimal for USAE-based coagulation monitoring due to synergistic effects.
- Tissue stiffness and absorption significantly impact USAE signal, with absorption providing a more linear response.