Evaluating atherosclerotic lesions by magnetic resonance imaging: from dimensional to compositional quantitation.

The article by Zhao et al 1 is the first definitive study to describe the use of high-resolution MRI to monitor the effects of intensive drug treatment on the dimensions and composition of atherosclerotic plaques in human carotid arteries. (An earlier brief rapid communication by Corti and coworkers2 described the effect of lipid-lowering therapy on carotid and aortic vessel dimensions but not plaque composition.) In this small case-control study, eight untreated patients with coronary artery disease were compared with eight patients treated for 10 years with triple lipid–lowering therapy (two carotids each). From the MR image slice that showed the largest plaque area in each carotid, the authors made both dimensional (total area, lumen area, and wall area) and compositional (area occupied by lipid deposits, fibrous tissue, and calcification) measurements. None of the dimensional measurements were significantly different in the two groups. Only the plaque lipid core areas were significantly reduced by lipid therapy (P50.01), although calcium content tended to be higher in treated patients. However, when the carotids were stratified according to their percent luminal area reduction, the upper tertile (n512 with 66% to 83% reduction) was significantly different from the other lower tertiles with respect to carotid wall area (P,0.01), lumen area (P,0.01), fibrous area (P,0.05), calcified area (P,0.1), and calcified/lipid-rich area (P,0.1).