Highly Sensitive Detection of Melanin in Melanomas Using Multi-harmonic Low Frequency EPR

Area of Science:

• Biophysics
• Medical Imaging
• Dermatology

Background:

• Electron Paramagnetic Resonance (EPR) can detect endogenous melanin free radicals in skin.
• Current clinical EPR has a low signal-to-noise ratio (SNR), limiting its sensitivity for diagnosing pigmented skin lesions.
• Melanin free radicals are potential biomarkers for distinguishing benign nevi from malignant melanoma.

Purpose of the Study:

• To evaluate the performance of multi-harmonic (MH) EPR analysis for enhanced detection of melanin.
• To compare the sensitivity of MH-EPR with classical continuous wave (CW)-EPR for melanin detection.

Main Methods:

• In vitro studies using melanin phantoms.
• In vivo studies using melanoma models in mice (skin, lymph nodes, lungs).
• Ex vivo studies using melanin phantoms on human skin surfaces.

Main Results:

• MH-EPR increased SNR by a factor of 10 in vitro compared to CW-EPR.
• In vivo, MH-EPR demonstrated improved sensitivity, enabling earlier detection of melanoma.
• MH-EPR successfully detected melanin signals in lymph nodes and lungs, and on human skin phantoms.

Conclusions:

• MH-EPR significantly boosts the sensitivity of clinical EPR for melanin detection.
• This technique shows promise for non-invasive characterization of pigmented skin lesions.
• Results support future clinical trials using MH-EPR for skin lesion diagnosis.