Use of HSI to measure oxygen saturation in the lower limb and its correlation with healing of foot ulcers in diabetes

AimTo explore the use of hyperspectral imaging (HSI) to predict healing of diabetic foot ulcers in patients with diabetes. MethodsWe used a HSI technique that incorporated novel software to account for tissue scattering of light, and was validated using blood samples of varying oxygen saturation assessed by blood gas analysis. HSI was then performed on a population newly presenting with diabetic foot ulcers to a specialist clinic, and associations were sought with healing at 12 and 24weeks. ResultsThe correlation between the results of HSI and blood gas analysis was strong (r=0.994). A total of 43 patients (mean sd age 62.712.2years; 31 men, 12 women; 37 with Type 2 diabetes, six with Type 1 diabetes) with foot ulcers were included in the prospective clinical study and underwent HSI within 16days of presentation. In all, 26 ulcers healed within 12weeks and 28 within 24weeks. There was a negative association between tissue oxygenation assessed by HSI at baseline and healing by 12weeks (P=0.009), and this was observed in both infected and non-infected ulcers. There was a significant positive correlation between oxygenation assessed by HSI and time to healing (P=0.03). No correlations were observed at 24weeks. ConclusionsThese findings suggest that HSI may predict healing in routine practice. The fact that the correlation between HSI and healing was negative could be explained by HSI being a measure of oxygenation of haemoglobin and there may be an inverse relationship between this and the oxygenation of extravascular tissue in people with neuropathy and/or microvascular disease.