PRECISION OF LASER-DOPPLER SCANNING IN CLINICAL USE

Reactions of the cutaneous microcirculation to local stimuli have been quantitated in terms of area of erythema (planimetry), change in colo ur (colorimetry) and time-dependent changes in perfusion (one-dimensio nal laser Doppler fluxmetry (LDF)). Using the new technique of laser D oppler scanning (LDS) it is now possible to quantify and demonstrate t wo-dimensional patterns of microvascular perfusion in terms of intensi ty and extent. The precision of this new technique was compared with t he previously established techniques by examining the reactions of 15 healthy volunteers to the intracutaneous injection of carbacholin and isotonic NaCl solutions. Both stimuli were applied paravertebrally, on the left and right side. Reactions were examined after 10 min. As a c ontrol for temporal reproducibility the examination was repeated on an other day. All methods allowed the differentiation of reactions to car bacholin from those to NaCl (P less than or equal to 0.0001). Only col orimetry and LDS provided data that were unequivocally reproducible wh en comparing both sides (r greater than or equal to 0.78). Using LDF o r planimetry, reproducibility of values was lower (r less than or equa l to 0.58). When looking at measurements performed on different days, only values of LDS were reproducible (r greater than or equal to 0.77) . Hyperaemic areas seen with LDS were significantly larger than those determined by planimetry. Results of LDS are reproducible spatially an d temporally: the technique will allow time-course observations of ski n reactions that are accompanied by medium-term changes in perfusion.