Abstract Number ‐ 255: Laser Speckle Flowgraphy As A Surrogate Marker For Symptomatic Carotid Stenosis

Abstract

Introduction The severity of internal carotid artery (ICA) atherosclerosis is assessed through measurements of degree of stenosis. This approach does not factor in mechanisms compensating for reduced distal perfusion, such as collateral circulation. An alternative approach is evaluating severity of carotid stenosis based on downstream changes in ocular perfusion. Laser speckle flowgraphy (LSFG) is a non‐invasive tool that quantifies intraocular blood flow. This pilot study investigated whether LSFG metrics could be surrogates for degree of stenosis. Additionally, we quantified changes in flow through the stenosed vessel before and after stenting usingsyngoiFlow (iFlow). Methods Fourteen patients had stents placed to treat symptomatic carotid stenosis. LSFG metrics were obtained before and after stenting. Mean blur rate (MBR), an index of ocular blood velocity, and associated waveform parameters were extracted from the optic nerve head (ONH) region of the eye. iFlow quantified time to peak (TTP), an index of peak cerebral contrast flow, by transforming digital subtraction angiography (DSA) images into perfusion heat maps.TTPswere extracted for seven regions of interest (ROIs) by two raters. Results Two LSFG waveform parameters were significantly negatively correlated with degree of stenosis. These parameters, flow acceleration index (FAI) and rising rate (RR), also increased significantly after stenting. Intraclass correlation coefficients calculated for TTPs showed substantial agreement across all ROIs. Significant decreases in TTP after stenting were observed in ROIs placed in the high cervical ICA, cavernous segment of the ICA, and brain parenchyma. Conclusions LSFG provides biometrics that can accurately measure the impact of ICA stenosis by quantifying distal perfusion. Indices of ocular blood flow acceleration may serve as surrogate metrics for degree of stenosis. iFlow is a sensitive tool to quantify changes in flow after stenting. Non‐invasive flow‐dependent methods are promising in the assessment of patients with ICA stenosis.