Variations of plantar thermographic patterns in normal controls and non-ulcer diabetic patients: Novel classification using angiosome concept

Thermometry of the plantar skin temperature has been one of the important parameters for assessing ulceration risks in diabetic patients. Recent progress of infrared thermographic technology allows us to obtain imaging of temperature distribution of the whole plantar skin. However, it has not been fully elucidated to what extent the individual variation of the plantar thermographic patterns shows different trends between normal controls and diabetics. In this study, we made a novel framework of conceptual classification with 20 different categories of plantar thermographic patterns according to the foot angiosome concept. The thermographic images from 32 normal volunteers and 129 non-ulcer diabetic patients, recruited from Diabetes Foot Outpatient Clinic of the University of Tokyo Hospital, were allocated to the above-mentioned framework categories. In the normal group, thermographic patterns of more than 65% of feet were allocated to the two typical categories, including the 'butterfly pattern' among the 20 categories, whereas 225 feet (87.2%) of the diabetic groups were variously allocated to 18 out of the 20 categories. This is the first study, which describes detailed plantar thermographic patterns, showing wider variations in the diabetic patients than in the normal subjects. Thermography will be one of the screening options to assess circulatory status in both daily foot care and surgical intervention.