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. (C) 2017. The Authors. Lasers in Surgery and Medicine Published by Wiley Periodicals, Inc.