It is generally believed small subcortical infarction (SSI) (also termed lacunar stroke) is caused by intrinsic diseases of penetrating arteries. Recent studies have shown the incidence of atherosclerosis in large arteries which is an important pathogenesis of large subcortical infarction (LSI) is also high in patients with SSI. This indicates the underlying mechanisms of SSI in patients with large artery atherosclerosis may be the same with LSI and inferred from plaque characteristics. However, the plaque characteristics ultimately leading to SSI or LSI remain unclear. This study is to explore the differences of plaque characteristics between patients with SSI and LSI.