Contact-free spectroscopy of leg ulcers: principle, technique, and calculation of spectroscopic wound scores.

Objective wound monitoring is an essential tool for evidence-based medicine in leg ulcers and other chronic wounds. Non-invasive and contact-free optical remittance spectroscopy seems to be a useful approach as it can provide additional information with respect to more traditional techniques of wound scoring. Twenty-three patients with chronic venous, arterial, and mixed leg ulcers were enrolled in this study. The clinical state of the ulcers was documented by a clinical wound score (quantity, color, and consistency of granulation tissue). The spectroscopic readings were performed with a novel diode-array spectrometer system in the visible and near-infrared range of the spectrum (400-1600 nm) with a resolution of 5 nm. The wound spectra mainly depend on the absorption of hemoglobin and water. The maximum correlation coefficients of mean remittance spectra with the clinical wound scores did not exceed +/- 0.5. Discriminant and cluster analysis were applied for spectral classification of wound scores. By using cross-validation the percentage of correct predicted wound scores was about 69%. Our results indicate that the application of optical visible and near-infrared spectroscopy could be a valuable remedy for the clinician.