Elevational diffraction effect in estimating the local attenuation-coefficient slope using...

Area of Science:

• Medical Imaging
• Acoustics
• Biomedical Engineering

Background:

• Quantitative ultrasound imaging relies on accurate attenuation coefficient slope (ACS) estimation.
• Reference-phantom-free ACS estimation methods are susceptible to diffraction bias.
• Synthetic transmit aperture (STA) imaging is a common ultrasound technique.

Purpose of the Study:

• To investigate the diffraction bias in reference-phantom-free ACS estimation for STA imaging.
• To identify the source of depth-dependent bias in ACS estimation.
• To evaluate the effectiveness of Gaussian diffraction correction in reducing ACS error.

Main Methods:

• Simulations and experimental studies were conducted using a one-dimensional linear array.
• The study focused on synthetic transmit aperture (STA) imaging.
• Gaussian diffraction correction was applied to mitigate bias.

Main Results:

• Elevational focus, not lateral focus, was identified as the source of depth-dependent bias.
• Bias caused ACS underestimation before focus and overestimation beyond.
• Gaussian diffraction correction reduced ACS error from ±0.28 to ±0.06 dB/cm-MHz (simulations) and ±0.32 to ±0.09 dB/cm-MHz (experiments).

Conclusions:

• Elevational diffraction significantly biases reference-phantom-free ACS estimation in STA imaging.
• Accounting for elevational diffraction is crucial for accurate quantitative ultrasound.
• Gaussian diffraction correction effectively reduces ACS estimation errors in STA imaging.