TERMINOLOGY

• Intracranial atherosclerotic vascular disease (ASVD)

• Intracranial atherosclerotic stenosis (ICAS)

IMAGING

• Gold standard is now high-resolution MR (HRMR) with

direct vessel wall imaging

○ HRMR vessel wall imaging > > depicting lumen (DSA,

CTA, MRA)

• Imaging findings (HRMR)

○ Crescent-shaped or eccentric thickening

○ May show asymmetric hyperintensity of intraplaque

hemorrhage on T1WI

○ Noncircumferential, short segment, irregular

enhancement

• CTA/MRA/DSA

○ Visualizes lumen, not wall

○ Warfarin-aspirin symptomatic intracranial disease

method for calculating ICAS

– % stenosis = [1- (diameter stenosis/diameter normal)]

x 100

○ Focal stenosis, luminal irregularities in cortical vessels can

mimic vasculitis

– Most common cause of vasculitic-like appearance at

angiography in middle-aged/older patient is

intracranial ASVD

TOP DIFFERENTIAL DIAGNOSES

• Vasculitis/arteritis

• Vasospasm

• Dissection

• Nonocclusive thrombus or embolus

CLINICAL ISSUES

• Disease burden of intracranial ASVD greatly

underestimated

• Most common cause of intracranial vascular stenosis in

adults

• Independent correlation with T2/FLAIR hyperintensities

(Left) Coronal graphic shows

atherosclerotic plaques

(ASVD) ﬊ involving the major

intracranial arteries and their

branches. Inset shows

penetrating (lenticulostriate)

arteries ſt and lacunar

infarcts ﬈. ASVD plaques are

typically short segment,

irregular, noncircumferential,

and may enhance. (Right) DSA

in a 68-year-old man in the ER

with an acute stroke shows

extensive intracranial ASVD.

Note multiple areas of

stenosis ﬈. An ulcerating

plaque ﬊ is also present in

the supraclinoid internal

carotid artery.

(Left) Axial T2WI shows a

typical pontine perforating

artery infarct ſt. The basilar

artery "flow void" ﬊ appears

normal. (Right) Vessel wall

imaging with thin-section 3T

T1 C+ FS MR in the same

patient shows enhancement of

the subacute infarct ﬇. A

partial rim of crescentic

enhancement in the basilar

artery wall is also present ſt,

consistent with chronic

inflammation within an ASVD

plaque.

Trauma, and Stroke

Brain: Pathology-Based Diagnoses: Malformations,

79