(HealthDay News) – Functional magnetic resonance imaging (fMRI) can be used to as a sensitive and specific tool to assess pain elicited by noxious heat in healthy persons, according to a study published in the April 11 issue of the New England Journal of Medicine.

Tor D. Wager, PhD, from the University of Colorado in Boulder, and colleagues developed an fMRI-based measure that predicts individual-level pain intensity. They conducted four studies involving 114 participants to identify the pattern of fMRI activity across brain regions (neurologic signature); assess its sensitivity to physical pain vs. warmth; assess the specificity relative to social pain; and measure the responsiveness to the analgesic agent remifentanil.

The researchers found that the sensitivity and specificity of the neurologic signature was ≥94% for discriminating painful heat from nonpainful warmth, anticipation of pain, and pain recall. In a new sample, the signature had 93% sensitivity and specificity for its ability to discriminate painful heat from nonpainful warmth. Discrimination between physical pain and social pain showed 85% sensitivity and 73% specificity in the third study; in a forced-choice test of which of the two conditions was more painful, the sensitivity and specificity was 95%. When remifentanil was administered, the strength of the signature response decreased considerably.

“It is possible to use fMRI to assess pain elicited by noxious heat in healthy persons,” the authors write. “Future studies are needed to assess whether the signature predicts clinical pain.”

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