['To retrospectively determine if in vivo magnetic resonance (MR) imaging can simultaneously depict differences between symptomatic and asymptomatic carotid atherosclerotic plaque.', 'Institutional review board approval and informed consent were obtained for this HIPAA-compliant study. Twenty-three patients (21 men, two women; mean age, 66.1 years +/- 11.0 [standard deviation]) with unilateral symptomatic carotid disease underwent 1.5-T time-of-flight MR angiography and 1.5-T T1-, intermediate-, and T2-weighted MR imaging. Both carotid arteries were reviewed. One observer recorded quantitative and morphologic information, which included measurement of the area of the lumen, artery wall, and main plaque components; fibrous cap status (thick, thin, or ruptured); American Heart Association (AHA) lesion type (types I-VIII); and location (juxtaluminal vs intraplaque) and type of hemorrhage. Plaques associated with neurologic symptoms and asymptomatic plaques were compared with Wilcoxon signed rank and McNemar tests.', 'Compared with asymptomatic plaques, symptomatic plaques had a higher incidence of fibrous cap rupture (P = .007), juxtaluminal hemorrhage or thrombus (P = .039), type I hemorrhage (P = .021), and complicated AHA type VI lesions (P = .004) and a lower incidence of uncomplicated AHA type IV and V lesions (P = .005). Symptomatic plaques also had larger hemorrhage (P = .003) and loose matrix (P = .014) areas and a smaller lumen area (P = .008). No significant differences between symptomatic and asymptomatic plaques were found for quantitative measurements of the lipid-rich necrotic core, calcification, and the vessel wall or for the occurrence of intraplaque hemorrhage or type II hemorrhage.'] Does comparison of symptomatic and asymptomatic atherosclerotic carotid plaque feature with in vivo MR imaging?