New theoretical equation improves accuracy of ultrasound imaging

Scientists at the University of Tsukuba have made a significant breakthrough in the field of ultrasound imaging by developing a new theoretical equation for the propagation of ultrasonic waves through liquid containing encapsulated bubbles. This research could potentially lead to the development of improved contrast agents and enhance the resolution of ultrasound imaging.

Ultrasound technology is widely used in modern healthcare due to its non-invasive nature and ability to provide detailed diagnostic images. It operates by emitting high-frequency sound waves from a transducer and detecting the echoes produced at the interfaces between different tissues with varying densities. By analyzing the time it takes for the echoes to return, a computer can reconstruct an image of the internal structures.

However, one limitation of ultrasound imaging is its relatively low resolution. To overcome this, contrast agents such as microbubbles are employed in procedures like echocardiograms or liver scans. Nevertheless, there is still a need for a deeper understanding of the physics behind the interaction between encapsulated microbubbles, which possess a thick shell, and sound waves to create more effective contrast agents.

The researchers at the University of Tsukuba have now developed new nonlinear equations that account for the compressibility of the bubble shell, extending the applicability of the equations to multiple bubbles. Previous studies often neglected the realistic properties of the bubble surface and focused primarily on the deformations of the bubble’s interior. However, the scientists found that considering the compressibility of the shell was crucial for accurately predicting the behavior of sound waves, resulting in an increased attenuation coefficient.

By modeling the shell as a viscoelastic object, the researchers have opened up possibilities for refining the theory of sound attenuation in liquids. Professor Tetsuya Kanagawa, one of the authors of the study, highlights the significance of their work in advancing our understanding of sound propagation in liquids. Additionally, the microbubbles investigated in this project may have potential therapeutic applications, such as targeted drug delivery. In this context, sound waves could be used to trigger the bursting of bubbles at specific locations or times, facilitating the release of the encapsulated drug.

The findings of this research have been published in the journal Physics of Fluids.

Source: University of Tsukuba

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