That’s a fact, ” osteoarthritis affected the cartilage, but also all the other tissues that make up joints, and in particular the bones, the synovial membrane – which lines the inside of the capsule delimiting the joint – and the ligaments”, specifies Jérôme Guicheux, Inserm research director. However, until now, radiography has been used to diagnose osteoarthritis, but it does not allow us to see cartilaginous and soft tissues. X-rays are only absorbed enough by dense tissue and bone to show up clearly in the image.
In the hope of having clearer shots, Emmanuel Brun and his colleagues in the laboratory Synchrotron radiation for biomedical research (Strobe) have been working for five years on “X-ray phase contrast imaging” (IPC). The technological advance is that it makes it possible to read the deflection of X-rays by the tissues, which is called refraction. Tissues thus appear more clearly on the images obtained.
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Improved definition and contrast
In 2020, six radiologists and rheumatologists from the Grenoble University Hospital evaluated various images of the hands and wrists obtained by radiography or by IPC. And the result was clear: it appeared that the ICP not only makes it possible to see simultaneously all joint tissues, dense and soft, but in addition, it produces images with improved definition and contrast. Contours appear sharper and internal structures clearer. On a smaller image of a mouse’s knee, the result was also positive. We could see there des micro-calcificationsdeposits of calcium crystals that accumulate in the soft tissues.
But the device used in Grenoble, the synchrotron, to carry out this research is 844 meters in diameter and costs 2 billion €. A less expensive solution exists: “We have integrated, in a conventional X-ray emitting device, a kind of sandpaper which allows a computer algorithm specially developed for this purpose to measure the deviation of X-rays… like in a synchrotron”, explains Emmanuel Brun. What arouse the hope that the imagery leads to a therapeutic breakthrough.