Advances in Cardiovascular Imaging Assessment of Skin Microvascular Function and Dysfunction With Laser Speckle Contrast Imaging

In recent years, skin microcirculation has been considered aneasily accessible and potentially representative vascular bed to evaluate and understand the mechanisms of microvascular function and dysfunction.1–3 Vascular dysfunction (including impaired endothelium-dependent vasodilation) induced by dif-ferent pathologies is evident in the cutaneous circulation.4–7 It has been suggested that the skin microcirculation may mirror generalized systemic vascular dysfunction in magnitude and underlying mechanisms.1 Furthermore, minimally invasive skin-specific methodologies using laser systems make the cutaneous circulation a useful translational model for investigating mech-anisms of skin physiology and skin pathophysiology induced either by skin disease itself or by other diseases such as vascular, rheumatologic, and pneumologic. To date, the skin has been used as a circulation model to investigate vascular mechanisms in a variety of diseased states, including hypercholesterolemia,8 Alzheimer disease,9 carpal tunnel syndrome,10 schizophrenia,11 hypertension,6 renal disease,12 type 2 diabetes,13 peripheral vascular disease,14 atherosclerotic coronary artery disease,2 heart failure,15 systemic sclerosis,16 obesity,17 primary aging,18,19 and sleep apnea.20 Assessment of skin microvascular function can be done by both invasive and noninvasive techniques. Among noninvasive techniques, laser systems are mainly used.21 The recent devel-opment of the laser speckle contrast imaging (LSCI) technique for monitoring skin microvascular function enables its use as a surrogate end point in clinical trials. LSCI allows for noncontact, real-time, and noninvasive monitoring of cutaneous blood flow changes.22,23 Recent evidence has shown that the LSCI tech-nique dramatically reduces the variability of clinical measure-ments compared with laser Doppler flowmetry (LDF), making the technique a fascinating tool to facilitate microvascular studies in clinical routine.23,24 In this review, we describe the potential of LSCI to assess microvascular function and dysfunc-tion. The way to use LSCI to understand skin physiology and physiopathology is also presented