| Objective To investigate the possibility of application of nuclide on the ApoE-/-mice plaque and investigate the best time of application of nuclide on the ApoE-/-mice, and elucidate the correlation between the nuclear imaging and histological imaging, estimate the feasibility of 18F-FDG on detecting vulnerable plaque; To investigate the possibility of application of nuclide on the ApoE-/- mice plaque by PET/CT.Methods (1) 8-week-old male ApoE-/- mice were fed with western diet (was provided by academy of military medical sciences) till 44 weeks as experimental group. After fasting for 10-12 hours,0.56-0.71 mCi 18F-FDG was injected into the mice tail vein. At30,60,90,120,150,180min after injection of the radiotracer sacrificed the mice and removed the aortas, incised longitudinally. Aortas were weighted, and radioactivity was measured with a well-typeγ-counter, the results were expressed as the SUV. Macroautoradiographies were acquired, aorta plaque and macrophage were investigated by examination of stained sections by Oil-red O staining and CD68 staining. Harvestings of aortas for en face analysis were performed with oil red O to compare with atuoradiography,and CD68 staining to compare with SUV. The control group C57BL/6N mice were fed with full diet, and the rest work were alike.Calculate the sensibility and specificity of the two group.(2) 8-week-old male ApoE-/- mice were fed with western diet (was provided by academy of military medical sciences) till 44 weeks as experimental group. After fasting for 10-12 hours,0.56-0.71 mCi 18F-FDG was injected into the mice tail vein. At 30,60,90,120,150,180min after injection of the radiotracer PET/CT images were acquired. Sacrificed the mice and removed the aortas, incised longitudinally and PET/CT images were acquired for the aorta. Aorta plaque and macrophage were investigated by examination of stained sections by Oil-red O staining and CD68+ staining.Harvestings of aortas for en face analysis were performed with oil-red O to compare with PET/CT. The control group C57BL/6N mice were fed with full diet, and the rest work were alike.Results①The sensibility of macroautoradiographies:The sensibility of experimental group at 30,60,90,120,150,180min were respectively74.07%,62.12%,57.09%,57.38%,57.14%,55.56%,30min were higher than other group(p<0.05).②En face measurements of aortas isolated 30 min after 18F-FDG injections (5.848±2.416:1, control group were negative result; there was a significant difference (0.243±0.054 vs 0.112±0.027, t=4.108, p=0.002) in the uptake of F-FDG between experimental group and control group; macrophage (Mf) number between experimental group and control group was significant different (4.99±0.51 vs 9.87±0.31, t=2.263,P=0.037)③It demonstrated an lower correlation between fat stainings and autoradiograp--hies (r=0.4697,p=0.001); the 18F-FDG uptake and macrophage (Mf) number in thoracic aortic segments had an good correlation(r=0.835,p=0.0002);macrophage (Mf) number in visualization plaque was was a significant different from unvisua--lization plaque (4.29±0.42 VS 10.85±1.47,t=10.55, P=0.015)④In the in vivo PET/CT:In 30min considerable radioactive uptake in heart,liver,kidney et al, and in heart it can last long time, non-specific radiotracer uptake the in plaque of atherosclerotic aortas, aortas visualization result showed 180min was better than others in gross appearance for radiotracer reduced in heart,liver,kidney,control group was similar with experimental group in 30min and aortas visualization was not imaged.⑤In the ex vivo PET/CT:There was no significant different in 30,60,90,120,150,180min of aortas visualization for lowly resolving power, en face of macro--autoradiographies and oil red O were probably similar, control group were negative result. Macrophage (Mf) number in visualizeation plaque was significant different from unvisualization plaque (4.29±0.42 VS 10.85±1.47, t=10.55, P=0.015) in the ex vivoPET/CT.Conclusions①18F-FDG can complete with glucose for uptake into metabolica--lly active cell like macrophage,the accumulation of 18F-FDG is in proporation to the metabolic activity of plaque, the highest sensibility is 74.07% in 30 min.②SUV and macrophage (Mf) number in thoracic aortic segments had an good correlation, these data show that SUV can reflect the degree of inflammation and instability.③Enhanced 18F-FDG uptake into macrophage may render this radiotracer a promising candidate for imaging plaques.But it demand further study. |
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