Investigation on the influence of the skin tone on hyperspectral imaging data interpretation for free flap surgery

The perfusion in cutaneous flap transplants needs to be monitored in order to detect vascular problems as early as possible. This can avoid tissue hypoxia and therefore, necrosis of the transplant. Since free flap transplant failures tend to happen more commonly during surgery than at a later onset, a non-contact real-time imaging device would be most advantageous. As hyperspectral imaging (HSI) is a new emerging modality to asses free flap perfusion contactless, this study aimed to investigate whether perfusion data can be interpreted appropriately using HSI, especially in regard to the individual skin tone. Further factors that might alter these HSI-interpretations, such as aging, BMI, different sexes or smoking habits, were also considered. Therefore, a prospective feasibility study was conducted, including 101 volunteers from whom images were taken on 16 different body sites. Skin pigmentation classification was performed using the Fitzpatrick skin type classification questionnaire and the individual typology angle (ITA) acquired from the images. Perfusion indices provided by the camera software were correlated to the possible influencing factors. The results show that a dark skin tone related to a high amount of melanin may influence the HSI-measurements and thus changes the HSI-derived perfusion indices. In addition, certain physiological influencing factors such as age, BMI and sex alter the tissue composition and qualities, thus showing measurement peculiarities within these groups. In conclusion, hyperspectral imaging can be used for perfusion assessment for people with lighter skin tone levels. Further developments are appreciated especially regarding skin pigmentation and the interpretation of indices of greater skin tone levels. 2023 The Author(s)