Dynamic MR imaging of the carotid wall

The purpose of this study was to clarify temporal changes of carotid wall enhancement using dynamic magnetic resonance (MR) and to correlate its findings with pathological conditions. Cervical carotid arteries of 84 consecutive patients were studied with a 1.5 T MR imager using phased array coils. Axial spoiled gradient-echo (SPGR) images (30-58 second scan time) with fat saturation were repeated 4-8 times after the injection of contrast material. We evaluated the presence and thickness of hypointense inner rims and hyperintense outer rims of the carotid wall, temporal changes of outer rim enhancement, and their changes in relation to pathological conditions. Hypointense inner rims and enhanced outer rims were clearly visualized in 87% (73/84) of our subjects. Enhancement of the outer rim was minimal in early phases and gradually increased. Patient age had a significant correlation with outer rim thickness. In the portions with large atheromatous plaques, inner rims were disrupted or thickened. A marked thickening of the outer rim was observed in one patient with arteritis. The outer rims adjacent to malignant tumors were often obscured. Our study suggests that dynamic MR images of the cervical carotid artery can uniquely demonstrate angiogenesis of the wall itself. The outer rim of the artery shows relatively rapid enhancement, and its thickness correlates with age.