A wound is cold for a reason. In a thoughtful new study from Gavish and colleagues at the Hebrew University of Jerusalem and the Scarborough Health Network in Toronto — published in Lasers in Medical Science — the authors flip a familiar therapy into a diagnostic challenge. They use photobiomodulation (PBM) not only as treatment, but as a kind of physiologic stress test, and watch what the skin tells them with a thermal camera.
The setup is simple and elegant. Twenty patients contributed 33 chronic leg ulcers — 22 diabetic foot ulcers and 11 venous ulcers — for prospective study at an outpatient wound clinic. Each wound was imaged with a FLIR C5 infrared camera at baseline, then every five minutes for half an hour after a near-infrared PBM session (808 nm, 250 mW peak power, 15 kHz). The question: do DFUs and VUs respond differently to PBM-induced microvascular activation, and can dynamic thermal imaging see it?
They did, and it can.
At baseline, the wound bed sat at roughly 27.7 °C — about 4.6 °C colder than the immediately surrounding skin, regardless of etiology. After PBM, the divergence began. Diabetic foot ulcers showed a sustained temperature rise of about 2.1 °C over the post-treatment window, while venous ulcers barely budged (mean ΔT ≈ 0.7 °C, not statistically significant). Even more interesting: among DFUs, the colder the wound at baseline, the larger the thermal response. Baseline temperature alone explained roughly 40% of the variance in PBM response, while wound area explained essentially none.
The mechanistic story the authors propose makes physiologic sense. DFUs are fundamentally a perfusion problem; PBM appears to drive a microvascular response that thermal imaging can capture as warming. VUs, by contrast, are dominated by venous valvular insufficiency and elevated hydrostatic pressure, and a vasodilatory probe does not solve that problem. The wound that does not warm is, in a sense, telling you it has a different upstream lesion than the one PBM is suited to address.
What I find compelling — beyond the data themselves — is the conceptual move. Using a therapy as a provocative test, then reading the answer with a passive, radiation-free, no-touch infrared camera, is the kind of clever repurposing that wound care has needed for a long time. We have spent two decades arguing about which patient gets which advanced therapy. A bedside test that takes 30 minutes and a small near-infrared device, and that can suggest who is likely to respond to PBM-driven microvascular stimulation, is exactly the sort of patient-specific optimization the field has been promising and rarely delivering.
Caveats, of course. Small sample, no sham control, no neuropathy stratification, no healing-outcome endpoint. The authors are appropriately measured. Larger, controlled studies tying acute thermal response to longitudinal healing trajectories would represent a meaningful next step. But as a proof-of-concept for a precision-wound-care diagnostic, this is a potential advance worth watching.
A nice piece of work. And a useful reminder: sometimes the most informative thing your therapy can do is fail in a structured way.
Reference: Gavish L, Ben Daniel D, Lo R, Grinbaum SO, Gertz SD, Hoffer O, Raizman R. Photobiomodulation combined with dynamic thermal imaging as a diagnostic tool for chronic leg ulcers. Lasers Med Sci. 2026;41(1). doi:10.1007/s10103-026-04878-5. PMID: 42053845.
#diabeticfoot #DFU #venousulcer #legulcer #photobiomodulation #LLLT #thermalimaging #infrared #microcirculation #perfusion #precisionmedicine #woundhealing #woundcare #SALSA #limbpreservation
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