Diffuse reflectance spectroscopy for monitoring diabetic foot ulcer – A pilot study

• The work deals with the application of diffuse reflectance spectroscopy for quantitatively determining tissue oxygenation levels in diabetic ulcer subjects.
• The ulcer sites show greater depressions at 542 and 580 nm in reflectance spectra indicating increased absorption of hemoglobin.
• The ratio R542/R580 increase and the ratio R580/R555 tend to decrease during the wound healing process.
• Ulcer sites show increased values of THb and changes in ISO2 related to the different stages of wound healing.

Foot ulceration due to diabetes mellitus is a major problem affecting 12–25% of diabetic subjects in their lifetime. An untreated ulcer further gets infected which causes necrosis leading to amputation of lower extremities. Early identification of risk factors and treatment for these chronic wounds would reduce health care costs and improve the quality of life for people with diabetes. Recent clinical investigations have shown that a series of factors including reduced oxygen delivery and disturbed metabolism have been observed on patients with foot ulceration due to diabetes. Also, these factors can impair the wound healing process. Optical techniques based on diffuse reflectance spectroscopy provide characteristic spectral finger prints shed light on tissue oxygenation levels and morphological composition of a tissue. This study deals with the application of diffuse reflectance intensity ratios based on oxyhemoglobin bands (R542/R580), ratios of oxy- and deoxy-hemoglobin bands (R580/R555), total hemoglobin concentration and hemoglobin oxygen saturation between normal and diabetic foot ulcer sites. Preliminary results obtained are found to be promising indicating the application of reflectance spectroscopy in the assessment of foot ulcer healing.