Letter to the Editor: Shear Wave Elastography May Be Superior to Grayscale Median for the Identification of Carotid Plaque Vulnerability: A Comparison with Histology
02 August 2015
02 September 2015
12 February 2016 (online)
We read this article with interest. The authors report that shear wave elastography (SWE) findings regarding plaque stiffness may be used to help identify vulnerable plaque . However, they found that there is a large overlap in Young’s Modulus values between stable and unstable plaques and this indistinctness requires attention to the interpretation of the ultrasound measurements for evaluating patients in routine clinical practice.
Because of the prominent role of carotid plaque in stroke incidence, their biomechanics have attracted significant scientific interest. There are several reports in the literature regarding the use of different methods to determine properties of plaque components   . In these methods, viscoelasticity is one of main parameters for clearly characterizing atherosclerotic plaques   . Elastography imaging is a novel ultrasound technique for quantifying tissue elasticity. However, studies have generally focused on the elastic properties of tissue, not on the viscosity . Moreover, it has been claimed that if viscosity is not regarded, measurements of stiffness can be biased, and the results may be greater than the real values  . Therefore, it is essential that viscosity be measured in order to fully characterize atherosclerotic plaques.
Garrard et al. could easily have analyzed the viscosity parameters of the atherosclerotic plaques because in a recent study, the viscosity in the liver was measured using post-processing techniques and the same ultrasound imaging system as Garrard et al. (Aixplorer, Supersonic Imagine, Aix-en-Provence, France) . We believe that the large overlap in Young’s Modulus might be decreased by adding viscosity measurements.
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