Abstract 12428: Evaluation of Symptomatic Carotid Plaques by Tissue Characterization Using Integrated Backscatter Ultrasound and Magnetic Resonance Imaging
Background: Unstable carotid plaques that consist of large lipid pool and intra-plaque hemorrhage are more likely to cause cerebral infarction. We previously developed an integrated backscatter (IBS) ultrasound color-coded mapping method to evaluate the tissue characteristics of plaques. The purpose of this study was to determine whether three dimensional (3D) IBS color-coded mapping and signal intensity ratio (SIR) from magnetic resonance imaging (MRI) could distinguish the acute symptomatic plaques from after treatment plaques.
Methods: We performed quantitative tissue characterization of carotid plaques measuring IBS ultrasound and the SIR from T1-weighted MRI images in 95 carotid plaques (>50% stenosis) in 95 patients (45 symptomatic, 50 asymptomatic).
Results: The % unstable component volume (UCV) that consisted of lipid pool and intra-plaque hemorrhage and the SIR of symptomatic carotid plaques were higher than those of asymptomatic plaques (57.8 ± 25.1 vs 46.8 ± 25.1%, p=0.036; 1.31 ± 0.25 vs 1.21 ± 0.26, p=0.047). In patients that were imaged within 3 days of symptom onset, the %UCV and SIR were significantly higher than the values in patients that were imaged 30–180 days after symptom onset (73.1 ± 18.4% vs 38.7 ± 18.4%, p<0.01; 1.38 ± 0.22 vs 1.22 ± 0.26, p=0.031). From the analysis of receiver operating characteristic curves, a %UCV of 50% (measured by IBS) and an SIR of 1.25 (measured by MRI) were the most optimal cutoff values for identifying acute symptomatic unstable plaques. Using these cutoff values, the sensitivity, specificity, positive and negative predictive values were 84%, 80%, 84% and 80% in the IBS analysis and 76%, 45%, 63% and 60% in the BB-MRI analysis, respectively.
Conclusions: Noninvasive quantitative tissue characterization of atherosclerotic lesions in carotid arteries using IBS ultrasound and MRI is useful to distinguish symptomatic unstable plaques from stable plaques.
- © 2010 by American Heart Association, Inc.