USPIO-enhanced MR Imaging In Atherosclerotic Plaques Of Rabbits

Partâ… :Three-dimensional contrast-enhanced MRA :comparison of an ultrasmall superparamagnetic iron oxide blood-pool contrast medium and gadopentetate dimeglumine in rabbitsObjective : To compare the intravascular enhancement of an ultrasmall superparamagnetic iron oxide (USPIO) blood-pool contrast medium to gadopentetate dimeglumine(Gd-DTPA ) for contrast-enhanced MR angiography (CE-MRA) in rabbits. Methods: Fourteen male New Zealand white rabbits were assigned to 2 groups randomly. One of the groups were perform CE-MRA with USPIO or Gd-DTPA,and a week delay ,to ensure the excretion of contrast agent,perform the MRA with the other contrast medium.MRA were performed in all the animals with a fast three-dimensional spoiled gradient recalled (SPGR) pulse sequence on a high-resolution GE 1.5T MR scanner with the cardiac coil. The contrast agent was administrated through the ear venous with high-pressure syringe . All the animals were imaged prior to and 9 times after administration of contrast medium ,then the perform was repeated at time 5,10,15,20,25,30 minutes. USPIO was injected intravenously at a dose of 0.1mmol/kg body weight,and Gd-DTPA was injected intravenously at a dose of 0.5mmol/kg . Results: All the animals fininshed the MRA , and satisfactory arterial enhancement were obtained with injection of contrast medium. SI (t) of aorta showed that the tendency of USPIO was as same as Gd-DTPA,but the SI peak of USPIO was lower than Gd-DTPA(P<0.05). SNR(t) and CNR(t) showed that there was a cross of USPIO and Gd-DTPA at the earily time,but USPIO was much higher than Gd-DTPA from 10 minutes(P<0.05). To view the aorta and the branches, there was no difference between USPIO and Gd-DTPA.Both arterial , venous and portal vein enhancement on delayed acquisitions ,and USPIO was much better than Gd-DTPA . Conclusion: USPIO is safer,longer acquisition time than Gd-DTPA ,which makes it more suitable for CE-MRA. Partâ…¡: Control study of USPIO-enhanced MR Imaging and Gd-DTPA-enhanced MR Imaging in atherosclerotic plaques of rabbitsPurpose: To explore the value of USPIO-enhanced MR imaging of atherosclerotic plaques in rabbits ,and compared with Gd-DTPA-enhacned MR imaging. Materials and methods: 35 male New Zealand white rabbits were randomly assigned to two groups. 25 rabbits were induced by atherogenic diet to set up the model. 10 rabbits with the normal diet were served as the control group. All MR imagings were performed on a high-resolution 1.5T MR scanner with the cardiac coil. Routine sequences included T1-weighted spin-echo, T1-weighted spin-echo with fat saturation, T2-weighted fast spin-echo, T2*-weighted gradient-echo. Up to 10 weeks,the blood of all the rabbits were gathered to test the content of total cholesterol. Then ,they were imaged prior to ,0 hour and 24 hours after administration of USPIO.A week delay ,to ensure the excretion of contrast agent,all the animals performed Gd-DTPA-enhanced MR imaging,then the rabbits were killed in different raising periods.And this was repeated every 2 weeks. All the rabbits were finished the whole study except for 5 model rabbits ,which were died a natural death. USPIO was injected intravenously at a dose of 0.05mmolFe/kg body weight. Gd-DTPA was injected intravenously at a dose of 0.25mmol/kg body weight. MR findings were correlated with histopathologic findings.Results:The total cholesterol in model group was obviously higher then the normal group(p<0.05). Rabbits induced by atherogenic diet were all developed atherosclerotic lesion on gross. The detection rate of 10 week model rabbit on MR was 40.0%,and rate was raising in the progress of lesions.And the lesions monitored by MR were well correlated with histopathologic findings. The analysis of electron microscopical and light microscope proved that the USPIO particles were in the macrophages of the plaque. USPIO-enhanced MR imaging characterize the composition of atherosclerotic plaques better then Gd-DTPA-enhanced MR imaging . Conclusions: MR imaging can dynamic monitor the progress of AS,and the early lesions can be detected.USPIO-enhanced MR imaging can help to depicting the vulnerable of atherosclerotic plaque ,and characterizing the composition of atherosclerotic plaques.