Von Mises Strain as a Risk Marker for Vulnerability of Carotid Plaque: Preliminary Clinical Evaluation of Cerebral Infarction

Non-invasive assessment of carotid artery plaque vulnerability is a key issue for cerebrovascular disease. This study investigates Von Mises strain imaging in patients by relating Von Mises strain to cerebral infarction presentation. Ultrasonography was performed in patients evaluated for carotid artery stenosis. Strains were estimated by a flow-driven diffusion method and least-squares regression applying Kalman filtering. Von Mises strains ɛ_VM^sys and ɛ_VM^dia were calculated by averaging four or five cardiac cycles in systole and diastole, respectively. Von Mises strain (peak, coefficient of variance, skewness and kurtosis) in patients with cerebral infarction was compared with that in the control group. Higher Von Mises peak strain localized to echolucent areas on B-mode imaging. Higher peak strain was found in patients with cerebral infarction compared with the control group (p = 0.02 for ɛ_VM^dia and p = 0.001 for ɛ_VM^sys). The area under the receiver operating characteristic curve for peak ɛ_VM^sys was 0.761 (p = 0.001) with high sensitivity and specificity. Peak strain also correlated with homocysteine (r = 0.345, p = 0.007, for ɛ_VM^dia; r = 0.287, p = 0.036, for ɛ_VM^sys) and hypersensitive C-reactive protein (r = 0.399, p = 0.043, for ɛ_VM^dia; r = 0.195, p = 0.034, for ɛ_VM^sys) levels. The coefficient of variance, skewness and kurtosis of ɛ_VM^dia or ɛ_VM^sys were also associated with homocysteine levels. In conclusion, this study indicates that peak Von Mises strain is a potential clinical risk marker for carotid plaque vulnerability and cerebral infarction.