There’s no single test to diagnose rheumatoid arthritis. Diagnosis of rheumatoid arthritis (RA), an autoimmune disease in which the body’s immune system attacks the lining of the joints, is traditionally made via a variety of tests, such as blood and imaging. A University of Birmingham pilot study published June 20, 2019, in the Journal of Biomedical Optics showed promise in using infrared light as a quick, noninvasive method of diagnosing the disease and monitoring treatment effectiveness.

Infrared Light May Make Earlier Diagnosis Possible

There’s no cure for RA, so this tool could potentially lead to earlier diagnosis and disease management, which provides better long-term outcomes. “Infrared light is harmless and can be used routinely. Also, as it provides information about the state of the disease, it can be an objective technique to help better understand progression of disease and therefore prognosis. In our limited study, we have shown good accuracy as compared with clinical evaluation by an expert. This could in turn allow a faster and more quantitatively accurate diagnosis,” says Hamid Dehghani, PhD, professor of medical imaging in the school of computer science at the University of Birmingham in England, who led the small study. More research is needed to validate the findings.

Light Therapy May Also Help Improve Rheumatoid Arthritis Treatment

“The potential of this technique is to allow the clinician to monitor treatment and disease progression. If a patient is not responding to a particular treatment, then this can be changed to improve outcome,” says Dr. Dehgani, who was assisted in this study by Daniel Lighter, doctoral researcher, and Andrew Filer, PhD, consultant rheumatologist, both at the University of Birmingham.

How Does Infrared Light (Low-Level Light Therapy) Work?

This new technique, which was developed by the University of Birmingham's School of Computer Science team in partnership with Health Technologies Institute and Rheumatologists in the NIHR Birmingham Biomedical Research Centre, uses three-dimensional digital imaging with infrared spectroscopy to create a three-dimensional image of blood content.

Light is absorbed by human tissue differently depending on its biological and functional condition. Particularly the amount of blood and water alters how much light passes through tissue and the amount of oxygen determines what colors are more strongly absorbed. RA alters the condition of tissue, specifically the amount of blood (due to increased vasculature and flow), amount of oxygen (hypoxia, a decreased oxygen supply to tissues, is due to increased metabolism), and amount of water (due to swelling). Through the infrared light imaging, “we can detect these subtle changes by measuring how much light travels through the finger, and at what wavelengths,” explains Dehghani.

A Step Toward Personalized Treatment for RA?

Dehghani believes this will be better for patient care, as they would not have to wait for an extensive period of time to be evaluated by a clinician during treatment. “This will reduce anxiety for the patient, potentially improving clinical outcome and overall reducing the cost of treatment,” he says.

A Word of Caution About 'The Light Touch'

Not all researchers are as optimistic about the future use of infrared light for a diagnostic tool. Howard B Cotler, MD, an orthopedic surgeon based in Houston, reports that “while we are always looking for a nonnarcotic and noninvasive care, the traditional blood study for early diagnosis is more accurate than infrared light, to my knowledge. You can’t make a definitive diagnosis due to a low-level light evaluation because it is a nondescriptive positive. It can’t differentiate between the different types of arthritis and antigens, as you can from other diagnostic tools. At this point, it is just not comparable with traditional care.”

He also points out that most insurance in the United States will not cover light therapy, so financially it doesn’t make sense either.

Infrared Light May Be Useful in Controlling RA Symptoms

Dr. Cotler does agree that light therapy can be helpful in controlling RA symptoms. “Low level laser therapy is very effective symptomatic care, but it is not a curative. However, it does not involve injections, medication, or narcotics and is not painful, and is good at decreasing pain, inflammation, and swelling,” he says.

He adds, “The point is symptomatic noninvasive care prior to definitive diagnosis is reasonable. But if symptoms don't respond and linger, then you need a diagnosis. See your doctor, because some arthritides are potentially life-threatening.”

Infrared Light May Be a New Way To Help Diagnose Rheumatoid Arthritis