SPATIAL HETEROGENEITY IN NORMAL SKIN PERFUSION RECORDED WITH LASER-DOPPLER IMAGING AND FLOWMETRY

Spatial and temporal variations in forearm skin perfusion captured by laser Doppler perfusion imaging (LDI) have been compared with topograp hic maps recorded by laser Doppler flowmetry. In order to determine th e shortest LDI sampling time required at each measurement site, with a n adequate signal-to-noise ratio and with the ability to display the h eterogeneity in skin perfusion, the noise-limited resolution of the LD I system as well as various sampling times were tested. The noise-limi ted resolution for medium and high light intensities were less than 0. 5% (temporal) and 0.3% (spatial) of full scale. A sampling time of 1 s ec was selected and image presentation was made by performing bilinear interpolation between perfusion values. The same area (10 x 10 mm) wa s mapped with LDI and topographic mapping at seven different sites. In addition, a larger area covering the surrounding skin was recorded wi th LDI. The small area recordings with LDI and topographic mapping cou ld be identified in the larger LDI image. High-and low-perfusion spots coincided between the two systems. Temporal variations were studied b y repeated LDI recordings of the same areas as above. Small spots were selected in the areas and plotted versus time. Without provocation, t he total perfusion changes at each spot showed large variations, but t he relative perfusion levels between neighboring spots persisted. Prov ocation with heat increased the perfusion in all spots. (C) 1994 Acade mic Press, Inc.