T. Tegos, A. Petrakis, A. Valavanis, A. Safouris, A. Papadimitriou, A. Orologas
A Neurology Department, AHEPA Hospital, Aristotelian University of Thessaloniki – Thessaloniki, Greece
Objective: Previous studies concluded that symptomatic carotid plaques are echolucent on ultrasound, whereas asymptomatic ones are echogenic. The aim of this study was to determine whether juxtaluminal plaque echogenicity (juxtaluminal 25% plaque area) constitutes a better discriminator of the symptomatic and asymptomatic status, as compared to global plaque echogenicity, in various degrees of stenosis.
Material and Methods: Analysis involved imaging by duplex of 100 carotid plaques of more than 50% stenosis (86 patients, 50 symptomatic and 50 asymptomatic plaques), capturing, digitisation and normalisation in a computer in a standard way. The global plaque Grey Scale Median (GSMglobal) was evaluated to distinguish dark (low GSM) from bright (high GSM) plaques. Subsequently, juxtaluminal 25% plaque area GSM (GSMjl25%) was evaluated semi-quantitatively in the same computer software. Stenosis was evaluated on duplex.
Results: In the group of plaques with 50-70% stenosis (n=40), the symptomatic ones were associated with median GSMglobal of 10 whereas the asymptomatic of 34 (p=0.0001). The corresponding values for median GSMjl25% were: 0 for symptomatic plaques and 47 for asymptomatic ones (p=0.0001). ROC curves failed to demonstrate an ability of GSMjl25% over GSMglobal in separating symptomatic from asymptomatic plaques (difference between areas: 0.068, p=0.172). In the group of plaques with 71-99% stenosis (n=60) the corresponding values were: median GSMglobal (symptomatic: 4, asymptomatic: 29), median GSMjl25% (symptomatic: 0, asymptomatic: 44). ROC curves demonstrated a more adequate ability of GSMjl25% over GSMglobal in separating symptomatic from asymptomatic plaques (difference between areas: 0.141, p=0.002).
Discussion: Our results suggested that juxtaluminal 25% plaque echogenicity might have a more adequate ability over global plaque echogenicity in separating symptomatic and asymptomatic carotid plaques, only in the presence of significant stenosis. This position might be solidified in natural history studies of asymptomatic individuals with carotid plaques, having as an end point the development of stroke.
Key words: carotid, plaque, stroke, ultrasound.