Magnetic Resonance Angiography Detection of Abnormal Carotid Artery Plaque in Patients With Cryptogenic Stroke

Abstract

BackgroundMagnetic resonance imaging of carotid plaque can aid in stroke risk stratification in patients with carotid stenosis. However, the prevalence of complicated carotid plaque in patients with cryptogenic stroke is uncertain, especially as assessed by plaque imaging techniques routinely included in acute stroke magnetic resonance imaging protocols. We assessed whether the magnetic resonance angiography–defined presence of intraplaque high-intensity signal (IHIS), a marker of intraplaque hemorrhage, is associated with ipsilateral cryptogenic stroke.Methods and ResultsCryptogenic stroke patients with magnetic resonance imaging evidence of unilateral anterior circulation infarction and without hemodynamically significant (≥50%) stenosis of the cervical carotid artery were identified from a prospective stroke registry at a tertiary-care hospital. High-risk plaque was assessed by evaluating for IHIS on routine magnetic resonance angiography source images using a validated technique. To compare the presence of IHIS on the ipsilateral versus contralateral side within individual patients, we used McNemar’s test for correlated proportions. A total of 54 carotid arteries in 27 unique patients were included. A total of 6 patients (22.2%) had IHIS-positive nonstenosing carotid plaque ipsilateral to the side of ischemic stroke compared to 0 patients who had IHIS-positive carotid plaques contralateral to the side of stroke (P=0.01). Stroke severity measures, diagnostic evaluations, and prevalence of vascular risk factors were not different between the IHIS-positive and IHIS-negative groups.ConclusionsOur findings suggest that a proportion of strokes classified as cryptogenic may be mechanistically related to complicated, nonhemodynamically significant cervical carotid artery plaque that can easily be detected by routine magnetic resonance imaging/magnetic resonance angiography acute stroke protocols.

Cryptogenic Stroke and Nonstenosing Intracranial Calcified Atherosclerosis

“…(2) Although case reports and case series have raised the hypothesis that nonstenosing plaque of the cervical and intracranial arteries may cause downstream artery-to-artery embolism, these analyses lacked the control groups needed to support a causal relationship. (13–17) We and others found a higher burden of vulnerable atherosclerotic plaque in the cervical ICA upstream of cryptogenic cerebral infarctions as compared to the unaffected ICA,(4,5) which more directly supports the hypothesis that some cryptogenic strokes may arise from unrecognized nonstenosing plaques. On the other hand, a recent analysis from a large population-based study argued against occult atherosclerotic disease as a cause of cryptogenic stroke.…”

“…(3) However, recent studies suggest that artery-to-artery embolism can occur from vulnerable plaque elements in the extracranial internal carotid artery (ICA) even in the absence of significant luminal narrowing. (4,5) It is unknown whether nonstenosing atherosclerotic lesions in the intracranial ICA are also associated with stroke.…”

Association between Carotid Plaque Features on CTA and Cerebrovascular Ischemia: A Systematic Review and Meta-Analysis

“…It is possible that a more directly applicable use of the results of our study may allow clinicians to improve their confidence in identifying a culprit lesion after a stroke of uncertain etiology has occurred so that optimal secondary stroke prevention measures can be initiated. 36,37 Second, we found that the time interval between the onset of ischemic symptoms and CTA for the evaluation of plaque features was relatively inconsistent among included studies. Third, many studies did not include precise descriptions of how causation of ischemic stroke was attributed to a given ICA.…”

Neurovascular 4DFlow MRI (Phase Contrast MRA): emerging clinical applications

“…Intracranial plaque morphology including intra-plaque hemorrhage [48,49] and increased lipid rich necrotic core volume [50] have also been established as stroke risk factors. In addition, carotid artery studies have demonstrated that complex plaque morphology including intra-plaque hemorrhage, thrombus or fibrous cap rupture is located predominantly on the ipsilateral side of stroke [51][52][53].…”