Appendix Table 5.

Criteria for Differentiating SCIs From Leukoaraiosis and Virchow-Robin Spaces

MRI Lesion	Location	T1-Weighted Imaging	T2-Weighted Imaging	FLAIR	Shape/Appearance	Size
WMH or leukoaraiosis	Periventricular vs. deep vs. subcortical WMH	Isointense or mildly hypointense to brain parenchyma	Hyperintense	Hyperintense	Punctate, small foci; or cap, pencil-thin lining; or nodular band	Variable
SCIs	Along vascular territories: Anterior circulation (anterior cerebral artery and middle cerebral artery); posterior circulation (posterior cerebral artery, basilar artery, superior cerebellar artery, anterior inferior cerebellar artery, and posterior inferior cerebellar artery); watershed territories (anterior and posterior external watershed, internal watershed, and cerebellar watershed)	Markedly hypointense similar to CSF	Hyperintense (similar to CSF)	Hyperintense or hypointense with no mass effect*	Focal, sharply demarcated, regularly or irregularly shaped areas	≥3 mm (variable)
Enlarged perivascular spaces or Virchow-Robin spaces or état criblé†	White matter (subregions of the frontal lobe, temporal lobe, parietal lobe, occipital lobe, and the centrum semiovale), basal ganglia region (including the caudate, lentiform nuclei, thalamus, internal capsule, substantia innominata, and insular area), brain stem, and hippocampal area (including the hippocampus, parahippocampal gyrus, and amygdalae)	Hypointense	Hyperintense	Hypointense (CSF-like content without abnormal surrounding signal intensity)	Small areas in the basal ganglia and centrum semiovale that follow the orientation of penetrating arterioles. They appear linear when parallel and dot-like when perpendicular to the imaging plane.	<3 mm‡

CSF = cerebrospinal fluid; FLAIR = fluid-attenuated inversion recovery; SCI = silent cerebral infarction; WMH = white matter hyperintensity.

^*Some lacunar infarctions may not progress to lacunes (i.e., they will not develop a cavity and remain hyperintense; therefore, they will be indistinguishable from nonspecific white matter lesions).

^†When there are several perivascular spaces, the brain can have a colander-like appearance referred to as état criblé.

^‡Rarely huge perivascular spaces may be seen, which can have positive mass effect.