Second harmonic ultrasonic blood perfusion measurement

Area of Science:

• Medical Imaging
• Ultrasound Technology
• Biomedical Engineering

Background:

• Evaluating blood perfusion is crucial for diagnosing various medical conditions.
• Existing methods for assessing blood flow have limitations in sensitivity and resolution.
• Nonlinear ultrasound contrast agents offer potential for improved diagnostic capabilities.

Purpose of the Study:

• To present and evaluate a novel method for blood perfusion assessment.
• To investigate the use of the second harmonic component of backscattered ultrasound echoes.
• To assess the efficacy of a galactose-based contrast agent for enhanced blood echo detection.

Main Methods:

• In vitro studies using excised sheep kidneys.
• In vivo studies on living rabbits with manipulated blood perfusion.
• Measurement of the Doppler shift of the second harmonic component of backscattered ultrasound echoes.
• Comparison of measurements at the fundamental and second harmonic frequencies.

Main Results:

• The galactose-based contrast agent demonstrated significant nonlinear backscattering properties in vitro.
• Utilizing the second harmonic measurement greatly improved the signal-to-clutter ratio compared to the fundamental component.
• The enhanced signal-to-clutter ratio allowed for the detection of blood flow in smaller vessels.
• The method showed potential for real-time determination of blood volume fluctuations.

Conclusions:

• The described method using second harmonic Doppler shift with a nonlinear contrast agent offers superior blood perfusion evaluation.
• This technique enhances the detection of microvascular blood flow.
• The findings suggest potential for real-time monitoring of tissue blood volume dynamics.