New X-ray technique images soft-tissue tumors clearer than MRI

Generally, X-rays are used to examine bones, while MRI and ultrasound are used to look at softer tissues. But an emerging method is adapting X-ray to image soft tissue, so that its higher resolution can reveal tumors or other problems earlier than other techniques. And now, researchers at Tohoku University have taken the first image using the new X-ray method, as a proof of concept.

Elastography is a field of medical imaging that focuses on the stiffness or softness of tissues. Shear waves are sent through the body, and then an imaging technology like ultrasound or MRI is used to watch how they spread. The waves move through stiff tissue faster than they do through soft tissue, and since tumors, lesions and hardened arteries are all stiffer than surrounding tissue, the technique can highlight these signs of disease.

X-rays usually work on a different mechanism, but recent research has suggested that they could be applied to elastography too. And if they were, the resulting images would be much higher resolution, able to spot things on the scale of microns instead of millimeters.

“This greater precision doesn’t just mean identification of much smaller or deeper lesions, but, importantly for patients, because smaller lesions can be newer ones, potentially also much earlier on in a disease or condition,” says Wataru Yashiro, lead researcher on the study.

And now, X-ray elastography has moved from principle to practice. The Tohoku team has taken the first images using the technique, and shown that it is able to identify the stiffness of different materials.

X-ray elastography images showing the stiffness of different materials – (left), a clear sample with no hard inclusions, and (right), a sample with harder materials to simulate tumors.

Wataru Yashiro, the Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University

The researchers imaged a polyacrylamide gel, with some samples containing harder particles of zirconium dioxide. Vibrations were then sent through these samples while X-ray images were taken. And sure enough, the X-ray elastography method was able to spot these tiny intruders.

After showing that the concept does work, the researchers say that the next steps are to create 3D images, and eventually develop x-ray elastography equipment for medical diagnoses.

The research was published in the journal Applied Physics Express.

Source: Tohoku University

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