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目的采用3.0 T磁共振波谱(1H-MRS)动态评估糖皮质激素诱导的兔骨质疏松模型骨髓脂质变化规律。方法将20只(5个月)雌性新西兰大白兔随机分为对照组及肌肉注射甲泼尼龙琥珀酸钠组(MPS组),每组10只。分别于0、4、8、12周行L3～L4及股骨近端MRS扫描及骨密度测定,获取骨髓脂质分数(LF)。第8周及12周各处死实验兔10只行病理组织学检查。结果第4、12周时,MPS组LF较基线时分别增高35.9%和75.2%(P值均<0.001)。第4周始,组间LF有显著性差异,而组间骨密度至第8周时差异有统计学意义(P<0.05)。第8、12周MPS组骨髓脂肪细胞密度较对照组分别增高57.1%和35.4%,而骨髓脂肪细胞直径分别降低13.3%、增高22.7%,骨髓脂肪细胞面积分别增高30.8%和53.8%。结论 MRS可以动态评估骨髓脂质变化规律。糖皮质激素诱导的骨质疏松初期骨髓脂肪以小尺寸脂肪细胞为主,后期以大尺寸脂肪细胞为主。
Objective To evaluate the changes of bone marrow lipid in glucocorticoid induced rabbit osteoporosis model by 3.0 T MR spectroscopy (1H-MRS). Methods Twenty female New Zealand white rabbits (5 months) were randomly divided into control group and intramuscular injection of methylprednisolone sodium succinate group (MPS group), 10 in each group. L3 ~ L4 and proximal MRS scanning and bone mineral density measurement were performed at 0, 4, 8 and 12 weeks respectively to obtain bone marrow lipid fraction (LF). At the 8th week and the 12th week, 10 rabbits sacrificed. The histopathological examination was performed. Results At 4 and 12 weeks, LF in MPS group increased by 35.9% and 75.2% respectively compared with baseline (P <0.001). At the beginning of the 4th week, there was a significant difference between the two groups of LF, but there was a significant difference between the two groups (P <0.05). The density of bone marrow adipocytes in MPS group increased by 57.1% and 35.4% respectively at 8th and 12th week, while the diameter of adipocytes decreased by 13.3%, 22.7% and 30.8% and 53.8%, respectively. Conclusion MRS can dynamically evaluate the changes of bone marrow lipid. Glucocorticoid-induced osteoporosis in the early bone marrow fat-based small fat cells, large fat-based late-based.