Role of CT angiographic plaque morphologic characteristics in addition to stenosis in predicting the symptomatic side in carotid artery disease

Abstract

Background and purpose: Atherosclerotic disease of the carotid artery is an important cause of ischemic stroke. We evaluated carotid plaque morphologic features by using CTA in addition to stenosis in the setting of symptomatic hemispheric TIA/stroke to identify factors that may predict plaque activity.

Materials and methods: Six hundred seventy-three patients (408 men; ages, 18-91 years; mean, 65.8 +/- 15.2 years) presenting with hemispheric ischemic symptoms and having a CTA that included imaging of both carotid arteries within 24 hours were studied. Scans were interpreted for morphologic features, such as plaque length and width, attenuation, shape, surface, presence and degree of calcification, and ILT in addition to stenosis.

Results: Univariable analysis showed that carotid occlusions (P = .01, OR = 5.27), high-grade stenosis (70%-99%) (P = .06, OR = 1.8), and the presence of ILT (P = .01, OR = 4.33) were highly predictive of the symptomatic side. Smooth plaque (P = .01, OR = 0.73) and extensive calcification (P = .03, OR = 0.72) were more commonly associated with the asymptomatic side. There was no correlation between plaque hypoattenuation (P = .7, OR = 1.06) or ulcerated plaque (P = .74, OR = 0.955) in predicting the symptomatic side. In a multivariable logistic regression model, the presence of ILT was still found to be significantly associated with the symptomatic side (P = .048, OR = 3.1) and the presence of extensive calcification, with the asymptomatic carotid artery (P = .047, OR = 0.69).

Conclusions: In addition to higher stenosis grades, the presence of ILT is highly predictive of the symptomatic side in carotid disease. Smooth plaque and extensive calcification seem to afford a protective effect. This information may be useful in radiologic risk stratification in carotid disease in addition to the current evidence available based on stenosis criteria alone.

Fig 1.

CTA images in separate patients showing hypoattenuated (A), isoattenuated (B), and heterogeneous attenuation (C) plaques.

Fig 2.

Sagittal reformatted CTA images of the carotid bifurcation in separate patients showing linear (A), sessile (B), and pedunculated (C) plaque shapes.

Fig 3.

Axial CTA images of the carotid artery in separate patients showing crescentic (A) and circumferential (B) plaque shapes.

Fig 4.

Sagittal reformatted images from the CTAs of separate patients showing smooth (A), irregular (B), and ulcerated (C) plaque surfaces.

Fig 5.

Axial images from CTAs of the carotid arteries in separate patients showing mild (A), moderate (B), and extensive (C) calcification.

Fig 6.

Axial CTA image showing an intraluminal thrombus (black arrow) as a central filling defect surrounded by hyperattenuating contrast agent (arrowhead).