Improved Sensitivity of Ultrasound-Based Subharmonic Aided Pressure Estimation Using Monodisperse Microbubbles

Area of Science:

• Biomedical Engineering
• Acoustic Imaging
• Medical Device Technology

Background:

• Subharmonic Aided Pressure Estimation (SHAPE) is a valuable noninvasive technique for measuring hydrostatic fluid pressures.
• Current SHAPE methods utilize polydisperse microbubbles, which may limit sensitivity and accuracy.
• Improving SHAPE sensitivity is crucial for broader clinical applications and enhanced diagnostic capabilities.

Purpose of the Study:

• To investigate the potential of monodisperse microbubbles to improve SHAPE sensitivity.
• To characterize the acoustic properties and stability of monodisperse microbubble populations.
• To evaluate the performance of monodisperse microbubbles in a hydrostatic pressure-controlled environment.

Main Methods:

• Monodisperse microbubbles were fabricated using microfluidics and characterized for size distribution and stability.
• Acoustic attenuation and resonance frequencies were measured to determine microbubble properties.
• SHAPE sensitivity was assessed using a clinical ultrasound scanner in a controlled pressure bath.

Main Results:

• Successfully created monodisperse microbubble suspensions (2.4–5.3 μm) with stable size distributions over 24 hours.
• Resonance frequencies correlated strongly with microbubble diameter (R² > 0.99).
• Monodisperse bubbles exhibited nearly double the SHAPE sensitivity (-0.17 dB/mmHg) compared to commercial polydisperse bubbles.

Conclusions:

• Monodisperse microbubbles offer a significant improvement in SHAPE sensitivity.
• This advancement holds promise for more accurate noninvasive hydrostatic pressure measurements.
• Further development could lead to enhanced diagnostic tools in various clinical settings.