Nonlinear beamforming for intracardiac echocardiography: a comparative study

Area of Science:

• Medical Imaging
• Ultrasound Technology
• Biomedical Engineering

Background:

• Intracardiac echocardiography (ICE) provides crucial intraoperative cardiac imaging but suffers from sidelobe and grating lobe artifacts.
• Conventional aperture apodization reduces artifacts but compromises essential lateral resolution in ICE.
• Advanced beamforming techniques are needed to enhance ICE image quality without sacrificing resolution.

Purpose of the Study:

• To comparatively evaluate five nonlinear beamforming algorithms for intracardiac echocardiography.
• To assess the performance of these algorithms in improving image quality, artifact suppression, and resolution.
• To determine the most effective beamforming method for ICE applications, including motion tracking.

Main Methods:

• Five beamforming algorithms were implemented and compared in ICE: nonlinear pth root delay and sum (NL-p-DAS), nonlinear pth root spectral magnitude scaling (NL-p-SMS), delay-and-sum with coherence factors (DAS+SCF), delay and sum with apodization (DAS+apodization), and conventional delay and sum (DAS).
• Algorithm performance was evaluated using phantom and ex-vivo experiments under static and dynamic conditions.
• Key metrics included lateral resolution, axial resolution, image contrast, sidelobe suppression, grating lobe suppression, and temporal resolution.

Main Results:

• DAS+SCF demonstrated the best lateral resolution.
• NL-p-SMS achieved the best axial resolution and superior suppression of grating lobe artifacts.
• All tested nonlinear methods improved image contrast and sidelobe suppression compared to conventional DAS; NL-p-SMS excelled in temporal resolution for motion tracking.

Conclusions:

• Nonlinear beamforming algorithms significantly enhance intracardiac echocardiography image quality over conventional DAS.
• NL-p-SMS offers the best combination of axial resolution, grating lobe artifact suppression, and temporal resolution.
• NL-p-SMS shows strong potential for improving diagnostic accuracy and motion tracking in ICE procedures.