Methods for quantifying ultrasound backscatter and two-dimensional video intensity: implications for...

Area of Science:

• Medical Imaging
• Biomedical Ultrasound
• Acoustical Physics

Background:

• Quantifying ultrasonic backscatter energy aids tissue characterization and echo contrast measurement.
• Traditional methods rely on ultrasonic video intensity, with integrated backscatter as the gold standard.
• Distinguishing detected backscatter from intrinsic tissue properties is essential.

Purpose of the Study:

• Review common ultrasonic backscatter quantification methods.
• Differentiate detected backscatter energy from the intrinsic tissue backscatter coefficient.
• Discuss potential quantification pitfalls.

Main Methods:

• Imaged rubber phantoms with known backscatter coefficients at multiple frequencies (2.5, 3.5, 5.0 MHz).
• Calculated acoustic backscatter intensity and tissue backscatter coefficient using calibrated video intensity.
• Evaluated a commercial acoustic densitometry system with integrated backscatter.

Main Results:

• Ultrasound attenuation and system factors significantly influence detected backscatter intensity.
• System transfer functions and attenuation correction are vital for accurate backscatter coefficient measurement.
• Excellent correlation (r=0.99) achieved between measured and phantom backscatter coefficients with corrections.

Conclusions:

• Uncalibrated video intensity and integrated backscatter have limitations for isolated tissue characterization.
• Reliable tissue backscatter coefficient measurement necessitates rigorous attention to imaging parameters and calibration.
• Calibration functions are essential for accurate ultrasonic tissue characterization.