Intracranial atherosclerotic plaque enhancement in patients with ischemic stroke

Abstract

Background and purpose: Inflammation of an atherosclerotic plaque is a well-known risk factor in the development of ischemic stroke and myocardial infarction. MR imaging is capable of characterizing inflammation by assessing plaque enhancement in both extracranial carotid arteries and coronary arteries. Our goal was to determine whether enhancing intracranial atherosclerotic plaque was present in the vessel supplying the territory of infarction by using high-resolution vessel wall MR imaging.

Materials and methods: High-resolution vessel wall 3T MR imaging studies performed in 29 patients with ischemic stroke and intracranial vascular stenoses were reviewed for presence and strength of plaque enhancement.

Results: Sixteen patients were studied during the acute phase (<4 weeks from acute stroke), 5 patients in the subacute phase (4-12 weeks), and 8 patients in the chronic phase (>12 weeks) of the ischemic injury. In all of the acute phase patients, atherosclerotic plaque in the vessel supplying the stroke territory demonstrated strong enhancement. There was a trend of decreasing enhancement as the time of imaging relative to the ischemic event increased.

Conclusions: Strong pathologic enhancement of intracranial atherosclerotic plaque was seen in all patients imaged within 4 weeks of ischemic stroke in the vessel supplying the stroke territory. The strength and presence of enhancement of the atherosclerotic plaque decreased with increasing time after the ischemic event. These findings suggest a relationship between enhancing intracranial atherosclerotic plaque and acute ischemic stroke.

Fig 1.

A, 3D reformatted MRA image demonstrating bilateral MCA stenoses (arrows). B, Diffusion-weighted image of the brain demonstrating areas of restricted diffusion/infarction in the left MCA territory. C, Coronal noncontrast T1-weighted image through the level of the MCAs. Atherosclerotic plaque is present in both the right MCA and left MCA (arrows) at the site of stenoses seen in A. D, Coronal postcontrast T1-weighted image at the same level as in C, with enhancement of the left MCA atherosclerotic plaque but not of the plaques on the right.

Fig 2.

A, 3D reformatted MRA image demonstrating right MCA stenoses (arrow). B, Axial noncontrast T1-weighted image through the level of the MCAs. Atherosclerotic plaque is present in the right MCA (arrow) at the site of stenosis seen in A. C, Axial postcontrast T1-weighted image at the same level as in B, with enhancement of the right MCA atherosclerotic plaque.

Fig 3.

A, 3D reformatted MRA image demonstrating midbasilar artery stenosis (arrow). B, Diffusion-weighted image of the brain demonstrating areas of restricted diffusion/infarction in the basilar artery territory. C, Coronal noncontrast T1-weighted image through the level of the basilar artery. Atherosclerotic plaque is present (arrow) at the site of stenosis seen in A. D, Coronal postcontrast T1-weighted image at the same level as in C, with enhancement of midbasilar atherosclerotic plaque.

Fig 4.

Strength and presence of enhancement versus time elapsed between imaging and initial stroke presentation on a logarithmic scale. Acute, subacute, and chronic timeframes are highlighted.

Fig 5.

Strength and presence of enhancement versus time elapsed between imaging and initial stroke presentation for 6 patients in whom imaging was performed at 2 separate time points.