Presence of intraplaque hemorrhage stimulates progression of carotid atherosclerotic plaques: a high-resolution magnetic resonance imaging study.

BACKGROUND: Previous studies suggest that erythrocyte membranes from intraplaque hemorrhage into the necrotic core are a source of free cholesterol and may become a driving force in the progression of atherosclerosis. We have shown that MRI can accurately identify carotid intraplaque hemorrhage and precisely measure plaque volume. We tested the hypothesis that hemorrhage into carotid atheroma stimulates plaque progression. METHODS AND RESULTS: Twenty-nine subjects (14 cases with intraplaque hemorrhage and 15 controls with comparably sized plaques without intraplaque hemorrhage at baseline) underwent serial carotid MRI examination with a multicontrast weighted protocol (T1, T2, proton density, and 3D time of flight) over a period of 18 months. The volumes of wall, lumen, lipid-rich necrotic core, calcification, and intraplaque hemorrhage were measured with a custom-designed image analysis tool. The percent change in wall volume (6.8% versus -0.15%; P=0.009) and lipid-rich necrotic core volume (28.4% versus -5.2%; P=0.001) was significantly higher in the hemorrhage group than in controls over the course of the study. Furthermore, those with intraplaque hemorrhage at baseline were much more likely to have new plaque hemorrhages at 18 months compared with controls (43% versus 0%; P=0.006). CONCLUSIONS: Hemorrhage into the carotid atherosclerotic plaque accelerated plaque progression in an 18-month period. Repeated bleeding into the plaque may produce a stimulus for the progression of atherosclerosis by increasing lipid core and plaque volume and creating new destabilizing factors.

March 2004: a 24-year-old woman with bifrontal headaches.

A 24-year-old woman with bifrontal headaches was found to have a well-circumscribed lesion in the frontal lobe subcortical white matter. Microscopic examination showed clusters of small round cells separated by hypocellular neuropil-like areas, and a distinct border between tumor and surrounding white matter. Synaptophysin was diffusely positive in neuropil-like areas, and many tumor cells expressed NeuN. Based on these findings, a diagnosis of "extraventricular neurocytoma" was made. A double-label immunofluorescence stain was performed with NeuN and Ki-67 antibodies to determine if NeuN+ cells remained in the mitotic cycle. No colocalization of these markers was found, thus supporting the hypothesis that neuronal differentiation (as marked by NeuN expression) is incompatible with continued proliferation of tumor cells, as well as normal neurons.

Classification of human carotid atherosclerotic lesions with in vivo multicontrast magnetic resonance imaging.

BACKGROUND: Recent studies demonstrated that in vivo and ex vivo MRI can characterize the components of the carotid atherosclerotic plaque, such as fibrous tissue, lipid/necrotic core, calcium, hemorrhage, and thrombus. The purpose of this study was to determine whether in vivo high-resolution multicontrast MRI could accurately classify human carotid atherosclerotic plaque according to the American Heart Association classification. METHODS AND RESULTS: Sixty consecutive patients (mean age 70 years; 54 males) scheduled for carotid endarterectomy were imaged with a 1.5-T scanner after informed consent was obtained. A standardized protocol was used to obtain 4 different contrast-weighted images (time of flight and T1-, PD-, and T2-weighted) of the carotid arteries. Best voxel size was 0.25x0.25x1 mm3. Carotid plaques were removed intact and processed for histological examination. Both MR images and histological sections were independently reviewed, categorized, and compared. Overall, the classification obtained by MRI and the American Heart Association classifications showed good agreement, with Cohen's kappa (95% CI) of 0.74 (0.67 to 0.82) and weighted kappa of 0.79. The sensitivity and specificity, respectively, of MRI classification were as follows: type I-II lesions, 67% and 100%; type III lesions, 81% and 98%; type IV-V lesions, 84% and 90%; type VI lesions, 82% and 91%; type VII lesions, 80% and 94%; and type VIII lesions, 56% and 100%. CONCLUSIONS: In vivo high-resolution multicontrast MRI is capable of classifying intermediate to advanced atherosclerotic lesions in the human carotid artery and is also capable of distinguishing advanced lesions from early and intermediate atherosclerotic plaque.