Quantification of vascular dysregulation in atopic dermatitis using laser Doppler perfusion imaging

The reactivity of cutaneous microcirculation to prostaglandin liberators and histamine has a wide variation in man. Especially patients with atopic dermatitis show frequently altered reactions like the paradox anemic reaction to nicotinic acid esters and the abnormally weak reaction to intracutaneous histamine injection. We wanted to investigate the reproducibility and sensitivity of two-dimensional laser Doppler perfusion imaging (LDPI) in quantifying these phenomena.

To study the reproducibility of LDPI, we measured the reaction to intracutaneous histamine injection and to application of nicotinic acid ester ointment at different time points and in contralateral body areas in 25 people with normal skin. In a second step, these stimuli were applied in 27 patients with atopic dermatitis and 23 normal controls in order to see whether LDPI is able to detect differences in the cutaneous vascular reaction between both groups.

We found an excellent reproducibility of the parameters of LDPI measurements with regard to different locations (0.847≤r≤0.948) and time points (0.686≤r≤0.935). After epicut-aneous application of nicotinic acid ester, there were significant smaller flow values in the marked center of the reaction in patients with atopic dermatitis compared to the control group. This corresponded to the paradox anemic reaction seen clinically in 15 of 27 patients. After intracutaneous injection of histamine, patients with atopic dermatitis showed significantly higher flow values in the center of reaction than normal controls because whealing was markedly reduced.

LDPI proved to be a reproducible and sensitive method for the follow-up of vascular reactions.