Techniques for perfusion imaging with microbubble contrast agents

Area of Science:

• Medical Imaging
• Acoustics
• Biomedical Engineering

Background:

• Ultrasound contrast agents exhibit diverse acoustic properties dependent on composition and insonation.
• Effective contrast imaging necessitates matching radiofrequency (RF) and Doppler processing to specific transmission parameters, agent, and tissue characteristics.

Purpose of the Study:

• To propose a generalized method for specifying RF and Doppler filter characteristics in ultrasound contrast imaging.
• To enhance agent-to-tissue contrast and optimize imaging performance across various techniques.

Main Methods:

• A novel method utilizing measured or modeled echoes from contrast agents and tissue to directly define RF and Doppler filter parameters.
• Application of the method to design filters for myocardial perfusion imaging with the Optison contrast agent.
• Comparison of simplified power Doppler filtering with matrix filters and evaluation of fundamental vs. harmonic RF filtering.

Main Results:

• The proposed method is adaptable to common imaging techniques like harmonic greyscale, Doppler, and pulse inversion.
• Coordinated RF and Doppler filter selection increased agent-to-tissue contrast by up to 3.9 dB compared to sequential design.
• Simplified power Doppler filtering demonstrated comparable performance to complex matrix filters.
• In specific scenarios, fundamental RF filtering proved superior to harmonic filtering for intermittent Doppler imaging.

Conclusions:

• A unified method for designing RF and Doppler filters can significantly improve ultrasound contrast imaging performance.
• Optimized filtering strategies, including simplified power Doppler and fundamental RF filtering, offer advantages under certain conditions.
• This approach provides a flexible framework for tailoring contrast imaging to specific agents and clinical applications.