Objectives: We sought to elucidate the effects of 20- mg versus 5- mg atorvastatin on thoracic and abdominal aortic plaques. Background: Regression of thoracic aortic plaques by simvastatin was demonstrated using magnetic resonance imaging(MRI). However, the effects of different doses of statin have not been assessed. Methods: Using MRI, we investigated the effects of 20- mg versus 5- mg atorvastatin on thoracic and abdominal aortic plaques in 40 hypercholesterolemic patients who were randomized to receive either dose. Treatment effects were evaluated as changes in vessel wall thickness(VWT) and vessel wall area(VWA) of atherosclerotic lesions from baseline to 12 months of treatment. Results: The 20- mg dose induced a greater low- density lipoprotein(LDL) cholesterol reduction than did the 5- mg dose(- 47% vs.- 34% , p< 0.001). Although 20 mg and 5 mg reduced C- reactive protein(CRP) levels(- 47% and- 28% ), the degree of CRP reduction did not differ between the two doses. The 20- mg dose reduced VWT and VWA of thoracic aortic plaques(- 12% and - 18% , p< 0.001), whereas 5 mg did not(+ 1% and + 4% ). Regarding abdominal aortic plaques, even 20 mg could not reduce VWT or VWA(- 1% and + 3% ), but instead progression was observed with 5mg treatment(+ 5% and + 12% , p< 0.01). Notably, the degree of plaque regression in thoracic aorta correlated with LDL cholesterol(r=0.64) and CRP(r=0.49) reductions. Although changes in abdominal aortic plaques only weakly correlated with LDL cholesterol reduction(r=0.34), they correlated with age(r=0.41). Conclusions: One- year 20- mg atorvastatin treatment induced regression of thoracic aortic plaques with marked LDL cholesterol reduction, whereas it resulted in only retardation of plaque progression in abdominal aorta. Thoracic and abdominal aortic plaques may have different susceptibilities to lipid lowering. Objectives: We sought to elucidate the effects of 20- mg versus 5-mg atorvastatin on thoracic and abdominal aortic plaques. Background: Regression of thoracic aortic plaques by simvastatin was demonstrated using magnetic resonance imaging (MRI). However, the effects of different doses Methods: Using MRI, we investigated the effects of 20- mg versus 5- mg atorvastatin on thoracic and abdominal aortic plaques in 40 hypercholesterolemic patients who were randomized to receive either dose. Treatment effects were evaluated as changes in Results: The 20- mg dose induced a greater low-density lipoprotein (LDL) cholesterol reduction than did the 5- mg dose (VWT) and vessel wall area (VWA) of atherosclerotic lesions from baseline to 12 months of treatment. (-47% vs. -34%, p <0.001). Although the 20% reduction in CRP reduction did not differ between the two doses. The 20- mg d Regarding hypothalamic VWT and VWA of thoracic aortic plaques (-12% and -18%, p <0.001), 5 mg did not (+ 1% and + 4%). Regarding abdominal aortic plaques, even 20 mg could not reduce VWT (+ 5% and + 12%, p <0.01). Notably, the degree of plaque regression in thoracic aorta correlated with LDL cholesterol (r = 0.64) and CRP (r = 0.49) reductions. Although changes in abdominal aortic plaques only weakly correlated with LDL cholesterol reduction (r = 0.34), they correlated with age treatment induced regression of thoracic aortic plaques with marked LDL cholesterol reduction, yet it resulted in only retardation of plaque progression in abdominal aorta. Thoracic and abdominal aortic plaques may have different susceptibilities to lipid lowering.