An experimental study on subharmonic-aided pressure estimation with commercial scanners

Area of Science:

• Medical Imaging
• Ultrasound Technology
• Biomedical Engineering

Background:

• Subharmonic-aided pressure estimation (SHAPE) is an ultrasound technique for pressure measurement.
• Ultrasound contrast agents are crucial for SHAPE performance.
• Calibration is essential for validating SHAPE accuracy.

Purpose of the Study:

• To evaluate the performance and reliability of SHAPE using ultrasound contrast agents.
• To assess the impact of microbubble stability and flow velocity on SHAPE.
• To determine optimal parameters for SHAPE sensitivity.

Main Methods:

• SHAPE was performed using Sonazoid contrast agent on a GE Healthcare Logiq E20 scanner in a phantom setup.
• Subharmonic time-intensity curves were analyzed under controlled flow and microbubble conditions.
• Pressure sensitivity was assessed across a range of mechanical index (MI) levels.

Main Results:

• Subharmonic amplitude showed a time-dependent decline, unaffected by flow velocity.
• SHAPE sensitivity was higher at broader MI levels compared to the traditional optimal MI.
• Linear correlation between subharmonic amplitude and pressure was observed (R2 > 0.9), but with significant time-series variations (2 dB SD).

Conclusions:

• SHAPE demonstrates sensitivity to pressure, but its clinical accuracy is questionable due to lowered sensitivity and substantial amplitude variations.
• Further research is needed to improve the consistency and reliability of SHAPE for clinical applications.
• Optimizing MI levels may enhance SHAPE performance, but time-dependent effects require mitigation.