Bilateral asymmetry in ultrasound-image-based mechanical and textural features in subjects with asymptomatic carotid artery disease

Carotid atherosclerosis is a principal cause of stroke and transient ischaemic attack. It has recently been postulated that potential asymmetries between the left and right carotids may be important in terms of disease progression. In this work, we sought to investigate differences between the two carotid arteries using ultrasound-image-based mechanical and textural features. Sixteen arterial segments (8 from the left and 8 from the corresponding right side) of elderly subjects with bilateral asymptomatic carotid atherosclerosis were interrogated. Left and right sides had similar stenosis degrees. Mechanical features were estimated via motion analysis using adaptive block matching. They included motion amplitudes, velocities and diastole-to-systole displacements of selected regions around and adjacent to the plaque. Textural features included first- and second-order statistical as well as multiresolution measures. One texture and eleven mechanical features were significantly different between the two arterial sides, indicating that bilateral asymmetry is characterised better in terms of mechanical properties, rather than via tissue composition, which is expressed through texture analysis. These findings suggest that not only systemic, but also focal, factors are probably responsible for atherosclerosis development. The identification and definition of the role of these factors may help to clarify the pathogenesis of this disease and to improve the clinical and therapeutic approaches.