Evolving Concept of Small Vessel Disease through Advanced Brain Imaging

Norrving, Bo

Abstract

Imaging plays a crucial role in studying and understanding cerebral small vessel disease. Several important findings have emerged from recent applications of advanced brain imaging methods. In patients with acute lacunar syndromes, diffusionweighted MRI studies have shown that the diagnostic precision of using clinical features alone or combined with CT scan findings to diagnose small vessel disease as the underlying cause is poor. Followup imaging studies on patients with acute infarcts related to small vessel disease have shown that the infarct may cavitate, merge into white matter disease abnormalities, or become invisible with time. High resolution MRI may demonstrate intracranial atherosclerosis in larger arteries (that may block orifices of penetrating arteries and cause small deep infarcts), but abnormalities in single penetrating arteries cannot as yet be consistently and reliably visualized for use in clinical practice. The epidemiology and risk factors of silent cerebral infarcts have been further delineated. Patterns of new incident silent infarcts appear related to existing white matter disease, suggesting similarities in pathophysiology. Silent deep infarcts causes local cortical atrophy, and can affect connectivity in the brain. Studies on cerebral microbleeds have shown consistent patterns in their effects on prognosis for a large number of outcomes, but the implications of cerebral microbleeds for treatment decisions remain to be established. Cortical microinfarcts represent the latest addition to the spectrum of small vessel disease in the brain, and appears as the most prevalent SVD entity. An important consensus document on neuroimaging standards for small vessel disease has been recently published.