Breakthrough ultrasound method can detect tension in human tissue

Researchers have developed a new ultrasound method that can, for the first time, measure tension in human tissue, potentially revolutionizing disease diagnosis.

An ultrasound device emits high-frequency sound waves towards internal body structures and records the sound reflected back to create an image in real time. Ultrasound is cheaper, quicker, and more accessible than other imaging techniques, such as MRI. It can show abnormalities that can only be seen with motion, for example, disease of the shoulder joint.

Diagnostic ultrasound is used to ascertain whether tissues or organs are functioning correctly. Non-invasive diagnostic ultrasound can be used to examine the abdomen, breasts, kidneys, pelvis, thyroid, muscles and bones, and blood flow. While ultrasound provides valuable information for diagnosing and treating various diseases and conditions, it has limitations.

One is ultrasound’s inability to measure the level of tension in human tissue. This prompted researchers from the University of Sheffield, in collaboration with researchers from Harvard, Tsinghua University, and the University of Galway, to develop a new ultrasound technique that can distinguish between stiff tissue and tissue that is under tension.

“When you go to the hospital, a doctor might use an ultrasound device to create an image of an organ, such as your liver, or another part of your body, such as the gut, to help them explore what the cause of a problem might be,” said Dr Artur Gower, one of the study’s authors. “One of the limitations of ultrasounds used in healthcare now is that the image alone is not enough to diagnose whether any of your tissues are abnormal.”

Human tissues are capable of sensing and responding to mechanical stress, adapting their shape accordingly. The forces of everyday muscular contractions add to that stress, meaning that all living tissues are under mechanical stresses, even when they’re at rest. Mechanical stresses also affect artificial soft materials such as wearable and implantable soft bioelectronics.

Stress measurement in tissues and artificial soft materials is important for determining proper functioning, but it is challenging to measure, so the researchers looked to the acoustoelastic effect for answers. The acoustoelastic principle, in simple terms, is this: the greater the tension, the faster sound waves spread.

Adapting a technique that is usually used to measure tension along railway lines, the researchers sent out two sound waves in different directions, relating the tension to the speed of the waves using a mathematical theory they’d developed.

Researchers used a particular type of wave called a shear wave, an elastic wave that can move through the body of an object, unlike a surface wave. With the use of shear waves, they were able to successfully measure tension, first inside hydrogel and then inside a pig's skeletal muscle.

It’s the first ultrasound method capable of measuring tension in any type of soft tissue, and the researchers are excited about its potential use.

“What we’ve done in our research is develop a new way of using ultrasound to measure the level of tension in tissue," Gower said. "This level of detail can tell us whether tissues are abnormal or if they are affected by scarring or disease. This technique is the first time that ultrasound can be used to measure forces inside tissue, and it could now be used to build new ultrasound machines capable of diagnosing abnormal tissue and disease earlier.”

Besides its potential in healthcare, the researchers believe the method will have application in other disciplines, like biomedical engineering, biology, and soft matter physics.

The study was published in the journal Science Advances.

Source: University of Sheffield