Table 1.

Description of the most commonly encountered plaque features and their typical imaging findings.

Plaque Feature	Definition/histopathologic correlate	US finding	CTA finding	MR finding
Calcification	Plaque calcification	Echogenic plaque with posterior acoustic shadowing	Plaque with density of at least over 130 HU	Profound hypointensity on all sequences
Intraplaque hemorrhage	Hemorrhagic plaque components	Echolucent plaque	Plaque with low attenuation in the 40–50 HU range	Hyperintense on all T1 and TOF sequences
Lipid-rich necrotic core	Necrotic core within lipid-rich plaque which contains macrophages and inflammatory cells	Echolucent plaque	Plaque with low attenuation in the 40–50 HU range	Hyperintense on T1 weighted sequences; Isointense on TOF
Plaque ulceration	Ulceration of the surface of the plaque leading to exposure of plaque materials to the lumen	Concavity along the surface of the plaque greater than 2 × 2 mm with Color Doppler signal within the concavity	Extension of hyperdense contrast beyond the vessel wall into the plaque by at least 1 mm	Surface irregularity on most MR sequences with extension of contrast beyond the lumen wall on MRA

HU=Hounsfield units; TOF=time-of-flight