Prediction of silent ischemic lesions after carotid artery stenting using integrated backscatter ultrasound and magnetic resonance imaging

Objective: A major concern with carotid artery stenting ( CAS) is the potential for cerebral embolism. The purpose of this study was to determine whether integrated backscatter (IBS) ultrasound and black-blood magnetic resonance imaging (BB-MRI) can predict the risk of a silent ischemic lesion after CAS. Methods: We performed quantitative analysis of plaque characteristics in carotid arteries using IBS ultrasound and BB-MRI before CAS in 50 patients. We measured IBS values and the signal intensity ratio ( SIR) from T1 weighted images of all plaques. We also performed diffusion-weighted (DWI) MRI of the brain before and after CAS. Results: In the patient group that was positive (n = 19) for newly appearing ipsilateral silent ischemic lesions (NISIL), relative unstable component area (%UCA) evaluated by IBS analysis (60.2 +/- 23.4% and 35.3 +/- 19.2%, p < 0.001) and SIR (1.40 +/- 0.19 and 1.18 +/- 0.25, p < 0.01) in most stenotic lesions were higher than in the NISIL-negative group (n = 31). From the analysis of receiver operating characteristic curves, 50% of the %UCA measured by IBS and an SIR of 1.25 measured by BB-MRI were the most reliable cutoff values for predicting NISIL. In multivariate logistic regression analysis, the independent predictors of NISIL were SIR (p = 0.030), the CRP level (p = 0.041) and the %UCA measured by IBS (p = 0.049). Conclusions: Quantitative tissue characterization of carotid plaques using IBS ultrasound and BB-MRI was useful to predict NISIL after CAS. The plaque components in carotid arteries should be evaluated by BB-MRI or IBS ultrasound before CAS to improve the clinical outcome of this procedure. (c) 2009 Elsevier Ireland Ltd. All rights reserved.