Detection of unstable carotid artery stenosis using MRI

Abstract

Background and purpose: Carotid artery stenosis can be classified by magnetic resonance imaging (MRI) as lesion types I-VIII according to a modified histological scheme based on American Heart Association (AHA) guidelines. Lesion types IV-V and VI are regarded as high-risk plaques.We aimed to evaluate the clinical relevance of this classification for identifying unstable plaques.

Methods: Eighty-five patients (29 female) with severe carotid artery stenosis (diagnosed by Doppler and duplex ultrasonography) were imaged using a 1.5 T scanner with bilateral phased-array carotid coils. T1-, T2-, time-offlight (TOF) and proton-density (PD)-weighted studies were obtained. The carotid plaques were classified as lesion types III-VIII according to the MRI-modified AHA criteria.

Results: Thirty-five patients presented with a recently symptomatic stenosis; 50 patients were asymptomatic. Lesion types IV-V (51.4 % vs. 22 %) and VI (20 % vs. 4%; P < 0.0001) were found significantly more often in symptomatic patients compared to those without a history of cerebral ischemia.

Conclusions: The distribution of lesion types differs significantly between symptomatic and asymptomatic carotid artery stenosis. High-risk lesion types IV-V and VI were overrepresented in recently symptomatic patients. MRI according to the modified AHA-criteria may be a suitable tool for detection of unstable carotid lesions.