Advances in atheroma imaging in the carotid

Improving atherosclerosis risk assessment: looking beyond plaque accumulation to imaging of embolization and healing

Cerebrovascular and cardiovascular diseases constitute the most substantial disease burden worldwide and are only increasing in importance. Understanding how individuals with atherosclerosis may be better assessed for risk of stroke and myocardial infarction will have immense importance in deciding on therapeutic options. Carotid atherosclerosis is frequently portrayed as an orderly progression from asymptomatic plaque formation that enlarges with aging and culminates in either stable, calcified plaque or vulnerable, ruptured and inflamed plaque. New evidence suggests that atherosclerosis is better described as an equilibrium between synthetic and degradative processes. Putatively, plaques heal and decrease in size through processes such as efferocytosis in individuals unlikely to experience symptoms, whereas individuals who experience symptoms lack reparative mechanisms. Present clinically employed imaging strategies overlook plaque healing mechanisms. Other approaches that examine the downstream effects of plaque, rather than static plaque measurement, such as ultrasound emboli signal detection may address the gap between plaque that is vulnerable in appearance and that which is actually likely to cause symptoms. To ascertain the clinical risk of atherosclerosis optimally, both sides of the equation must be examined instead of relying on a unidirectional accumulative approach to atherosclerosis.

Atherosclerotic carotid vulnerable plaque and subsequent stroke: a high-resolution MRI study

BACKGROUND

High-resolution contrast-enhanced magnetic resonance imaging (CEMRI) has been proven to be an effective tool for the identification of carotid atherosclerotic vulnerable plaque, such as a large lipid core and thin fibrous cap. The aim of this study was to evaluate the relationship between carotid plaque characteristics and the types of stroke in patients who had carotid artery (CA) stenosis > or =50%.

METHODS

102 consecutive subjects (mean age 67.2 +/- 10.2 years; 73 males) who initially had ischemic stroke or asymptomatic CA stenosis from 50 to 100% diagnosed by ultrasound were included in this study. Carotid CEMRI, brain MRI and magnetic resonance angiography were performed to understand the infarct patterns and to exclude intracranial artery stenosis. The modified American Heart Association (AHA) plaque classification was used in our study.

RESULTS

Our study demonstrated that 45 patients had CA stroke, and 55 patients had lacunar and asymptomatic lesions. The majority of patients had AHA classification type IV-V and VI which presented as vulnerable plaques. Of 63 patients with mild to moderate stenosis (< or =70%), 44 (69.8%) had type IV-V vulnerable plaques, which was significantly higher than those of patients with severe stenosis (>70%; p < 0.001). In CA stroke, the number of patients with a thin or ruptured fibrous cap was twice that of those with a thick and intact fibrous cap.

CONCLUSIONS

CEMRI may have important applications in clinical risk evaluations in CA atherosclerosis. Physicians ought to recognize that different types of stroke should be identified by brain MRI detection before invasive therapies.