Carotid Plaque Stiffness Measured with Supersonic Shear Imaging and Its Correlation with Serum Homocysteine Level in Ischemic Stroke Patients

Objective: To ascertain the feasibility of using shear wave velocity (SWV) in assessing the stiffness of carotid plaque by supersonic shear imaging (SSI) and explore preliminary clinical value for such evaluation. Materials and Methods: Supersonic shear imaging was performed in 142 patients with ischemic stroke, including 76 males and 66 females with mean age of 66 years (range, 45-80 years). The maximum, minimum, and mean values of SWV were measured for 129 carotid plaques. SWVs were compared between echolucent and echogenic plaques. Correlations between SWVs and serum homocysteine levels were investigated. Based on neurological symptom, the surrogate marker of vulnerable plaque (VP), binary logistic regression was performed and area under curve (AUC) of homocysteine only and homocysteine combing $SWV_{mean}$ was calculated respectively. Results: Echogenic plaques (n = 51) had higher SWVs than echolucent ones (n = 78) ($SWV_{min}$ 3.91 [3.24-4.17] m/s vs. 1.51 [1.04-1.94] m/s; $SWV_{mean}$, 4.29 [3.98-4.57] m/s vs. 2.09 [1.69-2.41] m/s; $SWV_{max}$, 4.67 [4.33-4.86] m/s vs. 2.62 [2.32-3.31] m/s all p values < 0.01). Pearson correlation analysis showed that stiffness of plaques was negatively correlated with homocysteine level. R values for $SWV_{min}$, $SWV_{mean}$, and $SWV_{max}$ were -0.205, -0.213, and -0.199, respectively. Binary logistic regression analysis showed that sex (p = 0.008), low-density lipoprotein (p = 0.015), triglycerides (p = 0.011), $SWV_{mean}$ (p = 0.004), and hyper-homocysteinemia (p = 0.010) were significantly associated with symptomatic ischemic stroke. Receiver operating characteristic curves revealed that $SWV_{mean}$ combing serum homocysteine level (AUC = 0.67) presented better diagnostic value than serum homocysteine only (AUC = 0.60) for symptomatic ischemic stroke. Conclusion: Supersonic shear imaging could be used to quantitatively evaluate stiffness of both echolucent and echogenic carotid plaques. More importantly, SWVs of plaques were not only correlated to serum homocysteine level, but also associated with symptomatic ischemic stroke, suggesting that SSI might be useful for understanding more about VP.