Background: Carotid artery stenosis is one of the major causes of ischemic stroke. Carotid intraplaque hemorrhage (IPH) plays a critical role in the progression of carotid atherosclerotic disease. Previous studies showed that IPH was associated with high intensity signal (HIS) on maximum intensity projection (MIP) images from routine three dimensional magnetic resonance imaging (3D-TOF MRA). The aim of this study was to evaluate the relationships among HIS, new ipsilateral ischemic stroke and a progression rate in carotid plaques with moderate stenosis.
Materials and Methods: We included 45 carotid plaques with moderate stenosis (50% to 69%) in 45 patients who could be followed more than 12 months. Carotid IPH was defined as the presence of HIS in carotid plaque on MIP image from routine 3DTOF MRA using the criteria previously we published. We analyzed the relation between the presence of HIS in the plaques and new ischemic strokes and annual progression rate of carotid stenosis.
Results: HIS in carotid plaque was present in 21 (47%) carotid arteries. Over a follow-up period of 24 ± 9 months, six ischemic strokes occurred ipsilateral to the index carotid artery. New ipsilateral ischemic stroke occurred more frequently in HIS positive group (6 of 21, 29%) than HIS negative group (0 of 24, 0%) (p=0.017). Annual progression rate of carotid stenosis is significantly higher in HIS positive group (+3.35%/year) than HIS negative group (-0.02%/year) (p= 0.0026). In multivariate regression analysis, HIS positive was an independent predictor for annual progression rate of carotid stenosis (p=0.003).
Conclusions: HIS in carotid plaques on 3DTOF-MRA MIP images are associated with new ischemic stroke and higher annual progression rate of stenosis. Evaluation of HIS in asymptomatic moderate carotid stenosis can potentially provide risk stratification of new ipsilateral ischemic strokes.