Despite the widespread acceptance of harmonic imaging in ultrasound, the mechanisms by which image quality is improved over conventional ultrasonography are not well understood. Three such mechanisms have been proposed in the literature, and these mechanisms have been demonstrated in water tank experiments. However, the significance of these mechanisms remain ambiguous for in vivo imaging. We hypothesize that elucidation of these mechanisms can lead to optimization of harmonic signal generation and yield further image quality improvement. We have developed powerful simulation tools capable of propagating nonlinear waves through various media including diffuse scatterers and layered and aberrating media in 3-D. These simulations are not limited to forward propagating waves, and can model mul- tipath reflections from diffuse scattering sites and reverberations from layered and aberrating media. We have also developed in vivo experimental techniques for characterizing each mechanism individually. We have developed these techniques to be used on a novel 1728 channel beamforming system capable of real-time 3-D imaging. We propose a series of experiments designed to separate and determine the contribution of each mechanism in vivo. These experiments are performed in the bladders and livers of volunteers and patients using the 1728 channel beamforming system. In addition, we propose novel simulation studies, informed by our in vivo experimentation, that are capable of 3-D nonlinear wave propagation. Based on our simulations and clinical studies, we propose optimization methods of harmonic signal generation and a second round of clinical studies to observe the optimized harmonic imaging methods in vivo.

Public Health Relevance

In this proposal, we address the physical mechanisms of harmonic imaging in ultrasound. The key problem is that these mechanisms are poorly understood when imaging the human body. We propose to expand our knowledge of these mechanisms and improve harmonic imaging methods based on this knowledge.

Agency
National Institute of Health (NIH)
Institute
National Institute of Biomedical Imaging and Bioengineering (NIBIB)
Type
Exploratory/Developmental Grants (R21)
Project #
5R21EB008481-02
Application #
7780023
Study Section
Special Emphasis Panel (ZRG1-SBIB-S (91))
Program Officer
Lopez, Hector
Project Start
2009-04-01
Project End
2012-03-31
Budget Start
2010-04-01
Budget End
2012-03-31
Support Year
2
Fiscal Year
2010
Total Cost
$193,050
Indirect Cost
Name
Duke University
Department
Biomedical Engineering
Type
Schools of Engineering
DUNS #
044387793
City
Durham
State
NC
Country
United States
Zip Code
27705
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Dahl, Jeremy; Jakovljevic, Marko; Pinton, Gianmarco F et al. (2012) Harmonic spatial coherence imaging: an ultrasonic imaging method based on backscatter coherence. IEEE Trans Ultrason Ferroelectr Freq Control 59:648-59
Pinton, Gianmarco F; Trahey, Gregg E; Dahl, Jeremy J (2011) Sources of image degradation in fundamental and harmonic ultrasound imaging: a nonlinear, full-wave, simulation study. IEEE Trans Ultrason Ferroelectr Freq Control 58:1272-83
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Pinton, Gianmarco F; Trahey, Gregg E; Dahl, Jeremy J (2011) Sources of image degradation in fundamental and harmonic ultrasound imaging using nonlinear, full-wave simulations. IEEE Trans Ultrason Ferroelectr Freq Control 58:754-65
Lediju, Muyinatu A; Trahey, Gregg E; Byram, Brett C et al. (2011) Short-lag spatial coherence of backscattered echoes: imaging characteristics. IEEE Trans Ultrason Ferroelectr Freq Control 58:1377-88
Lediju, Muyinatu A; Pihl, Michael J; Hsu, Stephen J et al. (2009) A motion-based approach to abdominal clutter reduction. IEEE Trans Ultrason Ferroelectr Freq Control 56:2437-49