Feasibility of 3D harmonic contrast imaging

Area of Science:

• Medical Imaging
• Ultrasound Technology
• Cardiovascular Imaging

Background:

• Improved endocardial border delineation is crucial for accurate left ventricular (LV) volume analysis.
• Contrast agents can enhance border definition, potentially simplifying LV volume calculations.
• 3D ultrasound imaging offers volumetric assessment capabilities for cardiac structures.

Purpose of the Study:

• To evaluate the feasibility of 3D harmonic contrast imaging for in vitro cardiac volume measurements.
• To optimize transducer settings for enhanced contrast-to-tissue ratio in harmonic imaging.
• To assess the accuracy of LV volume measurements using 3D harmonic contrast imaging.

Main Methods:

• Development of a fast rotating phased array transducer with harmonic capabilities for 3D cardiac imaging.
• In vitro evaluation using a tissue-mimicking flow phantom and Sonovue contrast agent.
• Optimization of excitation frequency, pulse length, and receive filter settings based on backscatter power spectra and contrast-to-tissue ratio.

Main Results:

• An increase of over 15 dB in contrast-to-tissue ratio was achieved near the second harmonic compared to the fundamental frequency.
• Optimal settings identified at 1.74 MHz excitation frequency and 2.5-cycle pulse length.
• Volume measurements of an LV phantom showed improved accuracy with contrast (3.8% error) compared to without contrast (1.5% error).

Conclusions:

• 3D harmonic contrast imaging is feasible for accurate volume measurements.
• Optimized harmonic imaging significantly enhances contrast detection.
• The technique shows promise for clinical evaluation in cardiac assessment.