MRI of rabbit atherosclerosis in response to dietary cholesterol lowering

Direct imaging of the atherosclerotic plaque, rather than the angiographic lumen, may provide greater insight into the response of atherosclerosis to cholesterol-lowering therapy. Aortic plaque was studied in vivo by MRI in r abbits undergoing dietary cholesterol intervention. Thirty-one rabbits unde rwent aortic balloon injury and high-cholesterol diet. for 4 months and the n were assigned to low-cholesterol versus continued high-cholesterol diet f or up to an additional 16 months. High-resolution (310 mu m) fast spin-echo MRI of the abdominal aorta was performed at 4. 12, and 20 months and compa red with histology. MRI demonstrated a significant reduction in % area sten osis in rabbits placed on low-cholesterol diet (44.6+/-2.1% at 20 months ve rsus 55.8+/-1.5% at 4 months, P=0.0002). In contrast, % area stenosis incre ased in rabbits maintained on high-cholesterol diet (69.8+/-3.8% at 20 mont hs versus 55.8+/-1.5% at 4 months, P=0.001). Similarly, plaque thickness de creased significantly in the low-cholesterol group (0.60+/-0.05 mm at 20 mo nths versus 0.85+/-0.06 mm at 4 months, P=0.006), with a trend toward incre ase in the high-cholesterol group (1.02+/-0.08 mm at 20 months versus 0.85/-0.06 mm at 4 months, P=0.1). Thus, in rabbits undergoing dietary choleste rol lowering, MRI detected regression of aortic atherosclerotic plaque in v ivo. Plaque progression was seen with maintenance of high-cholesterol diet. MRI is a promising noninvasive technology for directly imaging atheroscler osis and its response to therapeutic interventions.