ABSTRACT
Objective To evaluate the characteristics of arterial elasticity changes of abdominal aorta atherosclerosis in type 2 diabetic rats by using velocity vector imaging(VVI).Methods A rat model of diabetes mellitus(DM)were successfully established by a high-fat diet combined with the streptozotocin injection in thirty healthy male sprague-dawley rats.DM rats were randomly divided into five groups (n =6,each):0-week group (rats before treatment),4-week group (rats treated for 4 weeks),8-week group(rats treated for 8 weeks),the 12-week group(rats treated for 12 weeks),the 16-week group(rats treated for 16 weeks).The intima-media thickness(IMT)of abdominal aorta,the difference of end-systolic and end-diastolic vessel diameter(△D),resistance index(RI),pulsatility index (PI)and peak systolic velocity(Vs)were detected by ultrasound every 4 weeks.Peak radial velocity (PRy),PCs rate (PCs),peak circumferential strain (PCsr) and peak radial displacement (PRd) of abdominal aorta in short axis view were determined by VVI technique.Rats were sacrificed in different stages.Then,the specimens of abdominal aorta were collected,and observed by light microscope and electron microscope for the histopathological and ultrastructural changes in the atherosclerosis,respectively.Results Compared with 0-week group(0.25±0.03) mm and 4-week group(0.26 ±0.02)mm,IMT was thickened in the 16 weeks group(0.30±0.03)mm,(F=3.718,P=0.017).PRv,PCs,PCsr and PRd were lower after 8 weeks of treatment than in 0-week group.PRy,PCs,PCsr and PRd were lower in 16-week group than 0-week,4-week and 8-week groups (F =15.565,14.754,25.015 and 19.326,P＜0.01).Under the light microscope in abdominal aorta of rats in 12-week group and 16-week group,the stromal layer was thickened,smooth muscle cells were deformed and migrated to the tunica intima,and foam cells were formed.And under electron microscope,endothelial cells had a large amount of lipid attachment,and smooth muscle cells had vacuolar degeneration.Conclusions As compared with the two-dimensional ultrasound,velocity vector imaging can earlier find the elasticity change and intimal damage in abdominal aortic wall of diabetic rat,and can better analyze a motor function of the vascular wall.