High-Frame-Rate Contrast-Enhanced Echocardiography Using Diverging Waves: 2-D Motion Estimation and Compensation

Area of Science:

• Medical Imaging
• Ultrasound Technology
• Biomedical Engineering

Background:

• Contrast-enhanced echocardiography (CEE) using diverging waves (DWs) offers high temporal resolution for cardiac assessment.
• Current CEE techniques suffer from motion artifacts due to tissue and microbubble movement, degrading image quality.

Purpose of the Study:

• To develop and evaluate a correlation-based 2-D motion estimation technique for motion compensation in CEE with DWs.
• To assess the impact of motion compensation on image quality metrics (CR, CNR) and enable advanced cardiac imaging.

Main Methods:

• Employed correlation-based 2-D motion estimation for motion compensation in CEE using DWs.
• Validated the motion estimation accuracy using Field II simulations, achieving low root-mean-square velocity errors.
• Evaluated in vitro contrast ratio (CR) and contrast-to-noise ratio (CNR) improvements on a rotating disk phantom.
• Tested the motion correction algorithm in vivo on CEE data acquired with the Ultrasound Array Research Platform II.

Main Results:

• Simulations showed accurate motion estimation with normalized root-mean-square velocity errors of 5.9% (axial) and 19.5% (lateral).
• In vitro tests demonstrated significant improvements: a 12 dB increase in CR and a 7 dB increase in CNR compared to uncompensated data.
• In vivo application resulted in improved B-mode and contrast-mode image quality, mitigating cardiac and blood flow-induced microbubble motion artifacts.

Conclusions:

• The developed correlation-based 2-D motion estimation effectively compensates for motion artifacts in CEE with DWs.
• This technique enhances image quality and enables a novel triplex cardiac imaging modality (B-mode, contrast-mode, 2D vector flow imaging) at a high frame rate (250 Hz).
• This advancement holds potential for improved cardiac function assessment and blood flow interpretation.