Apodized adaptive beamformer.

Area of Science:

• Medical Ultrasound Imaging
• Acoustic Signal Processing
• Biomedical Engineering

Background:

• Ultrasound image quality, including spatial resolution and contrast, is crucial for diagnosis.
• Apodization is a key factor influencing ultrasound image quality.
• Previous adaptive beamforming studies, like amplitude and phase estimation (APES), primarily used rectangular apodization.

Purpose of the Study:

• To investigate the effects of different apodization functions on image quality in adaptive beamforming.
• To evaluate apodization's impact on spatial resolution and contrast in medical ultrasound.
• To explore apodization in a modified APES beamformer with sub-aperture beamforming.

Main Methods:

• A modified APES beamformer utilizing sub-aperture beamforming was employed.
• The receiving aperture was divided into four sub-apertures for APES beamforming.
• Apodization with rectangular, Gaussian, and two Hanning functions (for lateral modulation) was applied before delay-and-sum (DAS) beamforming.

Main Results:

• The modified APES beamformer achieved superior spatial resolution (0.38 mm) compared to conventional DAS (0.67 mm).
• Gaussian apodization further improved spatial resolution to 0.34 mm and contrast to 5.1 dB.
• Apodization with two Hanning functions (lateral modulation) enhanced image "tagging" compared to DAS with the same apodization.

Conclusions:

• Apodization is effective in enhancing adaptive beamforming performance.
• The modified APES beamformer with apodization shows potential for improved accuracy in measuring tissue lateral motion.
• Further research into apodization techniques can optimize ultrasound image quality and diagnostic capabilities.