Study Endpoints: Primary endpoint: Compared with standard dose rosuvastatin therapy 10mg/day, the change of relative cerebral blood flow (CBF) by CTP after intensive dose rosuvastatin therapy 20mg/day treatment for 52 weeks.Secondary endpoints: (1) Compared with standard dose rosuvastatin therapy 10mg/day, the changes of relative cerebral blood volume (CBV) by CTP after rosuvastatin 20mg/d treatment for 52 weeks (2) Compared with standard dose rosuvastatin therapy 10mg/day, the changes of relative mean transit time (MTT) by CTP after rosuvastatin 20mg/d treatment for 52 weeks (3) Compared with standard dose rosuvastatin therapy 10mg/day, the changes of lipid parameters (LDL-C, HDL-C, TG(Triglyceride), TC(Total Cholesterol), Apo A and Apo B ) after rosuvastatin 20mg/d for 52 weeks (4) Safety.