Swedish team tracks down soft tissue pain with PET scanner

Scientists at Sweden's Uppsala University said they've figured out how to use PET scanning and an injected tracer to visualize and track the progression of pain in a soft tissue injury. By doing so, they hope to better diagnose the mechanisms behind a given problem and come up with better treatments.

Details of their work are published in the journal PLoS ONE.

Can this be used to diagnose lingering injuries or pain of the elbow, arm or hand? Not yet, at least not cost-effectively. The researchers noted that PET is an expensive procedure, so it's not practical for everyday use in diagnosing and tracking pain. Consider their finding a first step. More research will help make this a routine process that aids in better diagnosis and targeting of pain that can in turn produce better treatment options, the team noted.

"In the future, we hope to be able to develop less expensive markers that enable us to use the method in everyday clinical practice," researcher Magnus Peterson said in a statement. "We also aim to create markers for other physiological processes that we know are active in chronic soft tissue pain."

For their work, the researchers focused on patients with chronic tennis elbow. They injected a tracer into the blood that circulates before binding to available NK1 receptors and then applied a PET scan. It was a simple process that revealed a lot: a higher level of NK1 in injured portions of the arm versus a healthy arm.

The researchers captured what happens in the wake of a tissue injury. When tissue damage takes place, the neuropeptide substance P and the NK1 receptor are upregulated, the researchers said, a process that can linger in an injury such as chronic tennis elbow. It is also part of a broader interaction between peripheral nerves, immune cells and the injured tissue that the researchers said seems to be behind the body's process of repairing itself.

The quest to find ways to diagnose pain continues in other places. Researchers at the University of Colorado, Boulder, for example, believe they've found a distinct neurological pattern that reflects response to pain caused by heat. Meanwhile, researchers at Harvard Medical School and the Martinos Center for Biomedical Imaging believe they have come up with an MRI technique to measure blood flow to particular brain regions that can help diagnose chronic pain.

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