Dynamic thermographic imaging method for quantifying dermal perfusion: potential and limitations

Abstract

A new method of quantifying dermal perfusion on a regional basis using a dynamic thermographic technique is investigated. The technique is based on the relationship between dermal perfusion and the rate of skin surface reheating following the application of a transient cold challenge predicted by a theoretical model. Measurements were made using images from a Philips thermographic camera under rigorously controlled conditions. Experimentation on undisturbed volar forerm skin of normal subjects showed that measurements could be repeated with good accuracy but that differences in normalised reheat temperatures between subjects were highly dependent on subcutaneous fat thickness. Comparisons between normal and occluded foreams indicated that reheat temperatures were not sensitive to changes in low levels of dermal perfusion. Conversely, stimulation of dermal blood flow with prostaglandin E₂ did produce significant differences from control conditions, but quantifying the axtent of this hyperaemia was limited by the effects of intersubject variations in fat thickness. Quantifying skin blood flow from skin temperature reheat rates is shown to be limited by a lack of sensitivity and a dependence on subcutaneous fat thickness, although dynamic thermography is able to provide useful information on regional variations in skin perfusion which could not be reliably obtained from static temperature measurements alone.