Changes in carotid plaque echomorphology with time since a neurologic event

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Abstract

Purpose:

Symptomatic carotid plaques are characterized by reduced fibrous tissue content, increased lipid content, intraplaque hemorrhage, and cap rupture. This confers an increased stroke risk. Plaque remodelling reduces this risk, however, and this study has evaluated differences in echomorphology at varying times after a neurologic event.

Methods:

Gray scale medians (GSM ± interquartile ranges) were measured using the best single longitudinal (SLV) and multiple cross-sectional views (MCSV; transverse views, 5-mm intervals throughout plaque) on B-mode ultrasound images of 61 carotid plaques (70% to 99%) causing symptoms ≤30 (n = 20), 31 to 90 (n = 10), 91 to 180 (n = 16), or >180 days (n = 15). The results were compared with those in 47 asymptomatic plaques. Plaque echolucency (SLV-GSM, MCSVmin-GSM [cross-sectional image with lowest GSM]) and heterogeneity (MCSVmax−min-GSM [highest minus lowest GSM of cross-sectional views]) were determined.

Results:

In symptomatic plaques, echolucency was maximal ≤30 days of the presenting neurologic event (SLV-GSM,P= .009; MCSVmin-GSM,P= .004). Although this diminished between 31 to 90 days, MCSV measurements in particular suggested increased echolucency (P= .042 at >180 days) and continuing heterogeneity (P= .01 at 91 to 180 days) beyond that time.

Conclusions:

Plaque echolucency was maximal ≤30 days of a neurologic event but diminished after 1 to 3 months, suggesting remodelling of unstable plaques. Continued features of increased echolucency and heterogeneity >91 days, however, suggests an increased stroke risk in these patients compared with that of the general population.

Clinical Relevance:

This cross-sectional study has demonstrated interesting differences in gray scale median plaque echomorphology with time after the initial neurologic symptom in patients with symptomatic carotid disease. The results raise some important questions with respect to identifying currently asymptomatic patients who might be at greatest risk of a neurologic event and add fuel to the current debate relating to the relative benefits of either carotid endarterectomy or carotid angioplasty and stenting in patients with recent symptoms.

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