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Determining carotid plaque vulnerability using ultrasound center frequency shifts

      Highlights

      • An ultrasound method for assessing carotid plaque vulnerability is proposed.
      • The method is based on shifts in ultrasound center frequency caused by tissue.
      • The center frequency shift is related to carotid plaque vulnerability.

      Abstract

      Background

      The leading cause of morbidity and mortality worldwide is atherosclerotic cardiovascular disease, most commonly caused by rupture of a high-risk plaque and subsequent thrombosis resulting in stroke, myocardial infarction or sudden death depending on the affected arterial territory. Accurate, non-invasive methods to identify such lesions known as vulnerable or high-risk plaques are currently sub-optimal. Our aim was to validate a new non-invasive ultrasound method to identify high-risk carotid plaques.

      Methods

      We evaluated a new method based on the center frequency shift (CFS) of the ultrasound radio frequency data obtained from carotid plaques compared to a reference phantom. We evaluated the method both ex vivo, on 157 sections from 18 plaques, and in vivo, in 39 patients 1-day prior to carotid plaque removal, and correlated the data with histology.

      Results

      The CFS correlated with a plaque vulnerability index based on histological areas stained for lipids, macrophages, hemorrhage, smooth muscle cells and collagen (r = −0.726, P = 1.7 × 10−8). Plaques with CFS below median had larger cores, more macrophages and were less rich in collagen in agreement with the definition of rupture-prone plaques. The accuracy to detect plaques with high vulnerability index was 78% (confidence interval (CI) 61–89%), with sensitivity 77% (CI 61–89%) and specificity 78% (CI 62–89%).

      Conclusions

      Our method is the first to characterize atherosclerotic plaque components that affect plaque vulnerability using CFS.

      Keywords

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