Validation of near-infrared laser speckle imaging for assessing microvascular (re)perfusion

The present study was conducted to compare laser speckle imaging (LSI) with sidestream dark field (SDF) imaging (i.e. capillary microscopy) so as to validate the use of LSI for assessing microvascular (re)perfusion. For this purpose, LSI and SDF measurements were performed on the human nail fold during gradual Occlusion of the upperarm circulation to modify nail fold perfusion under controlled circumstances Additionally, a vascular occlusion test was performed to test the ability of 151 to detect rapid changes in tissue perfusion dining reactive hyperemia and a hyperthermic challenge was performed to measure LSI perfusion at maximum functional capillary density. Normalized LSI measurements (i e, normalized to baseline is 100%) were shown to correlate positively with normalized SDF measurements (Pearson's r=0.92). This was Supported by linear regression analysis (slope of 1 01, R-2=0.85, p<0 001) During the vascular occlusion test. LSI perfusion decreased from 307 +/- 90 AU (baseline) to 42 +/- 8 AU (ischemia). Peak perfusion during reperfusion was 651 +/- 93 AU (212% of baseline), which had returned to baseline after 2 min Hyperthermia increased LSI perfusion from 332 90 AU to 1067 +/- 256 AU (321% of baseline) The main finding was that changes in perfusion as measured by LSI correlated well with changes in capillary red blood cell velocities as measured by SDF imaging during controlled reduction of the (micro)vascular perfusion It was further shown that LSI is capable of measuring tissue perfusion at high temporal and spatial resolution In conclusion, LSI can be employed to accurately quantitate microvascular reactivity following ischemic and hyperthermic challenges (C) 2010 Elsevier Inc. All rights reserved