Novel assessment tool based on laser speckle contrast imaging to diagnose severe ischemia in the lower limb for patients with peripheral arterial disease

OBJECTIVE: We propose a new assessment tool to diagnose severe ischemia of the lower limb in peripheral arterial disease, using laser speckle contrast imaging to evaluate heating-induced microcirculatory fluctuations in the proximal and distal sites of the dorsal foot. STUDY DESIGN: A cross-sectional study. METHODS: We recorded the slope describing the behavior of perfusion values (decrease or plateau) following the initial, heating-induced increase in perfusion in 63 feet of patients with clinical signs of peripheral arterial disease. RESULTS: The plateau and decrease groups were defined as having perfusion slopes of <0.20 and ≥0.20 PU/min, respectively. Transcutaneous oxygen tension was significantly lower (P < 0.001) in the plateau than in the decrease group (8 vs. 45 mmHg), indicating more severe ischemia. The laser speckle contrast imaging thermal load test discriminated transcutaneous oxygen tension <30 mmHg with good sensitivity (78.7%) and specificity (96.2%), and an area under the curve of 0.908. CONCLUSIONS: Both transcutaneous oxygen tension and the laser speckle contrast imaging thermal load test are useful in diagnosing severe ischemia in the foot. Lasers Surg. Med. 49:645-651, 2017.