磁共振评估去卵巢大鼠铁过载与骨质疏松的相关性

Magnetic resonance evaluations of correlation of iron overload and osteoporosis in ovariectomized rats

目的 探讨肝脏磁共振（MR）-T2＊弛豫时间与去卵巢（OVX）模型鼠骨质疏松发生发展中骨密度的相关性.方法 对假手术及OVX大鼠共60只术前及术后1～3个月分别双能X线骨密度仪（DEXA）检测下腰椎骨密度及肝脏3.0 T MR-T2＊ map行T2＊弛豫时间测量,结合生化及显微CT骨微结构指标,分析肝T2＊弛豫时间评估骨质疏松的敏感性及其与骨密度有无相关性.结果 OVX组大鼠在术后2个月时骨密度明显低于假手术组[（554±27） mg/cm3）比（722±19） mg/cm3,P＜0.05].术后第2个月时,两组血清铁蛋白浓度[（521±41） ng/ml比（441 ±29） ng/ml]及肝铁浓度[（291 ±18） μg/g比（237 ±27） μg/g]差异均有统计学意义（均P＜0.01）.术后1个月OVX组肝脏MR-T2＊弛豫时间明显低于假手术组[（13.2±0.7）ms比（13.9±0.4） ms,P＜0.01）].假手术组肝脏T2＊弛豫时间值与骨密度呈正相关（r =0.410,P＜0.01）,OVX组肝脏的T2＊弛豫时间值与骨密度亦呈正相关（r =0.434,P＜ 0.01）.结论 肝脏MR-T2＊弛豫时间能较敏感地发现绝经后早期骨质疏松.

Objective To explore the correlation between liver T2 ＊ value and bone mineral density （BMD） in ovariectomized （OVX） rats.Methods A total of 60 rats,including sham （n =25） and OVX （n =35） groups,underwent dual-energy X-ray absorptiometry （DEXA） and liver magnetic resonance （MR）-T2 ＊ mapping for lumbar vertebra BMD and T2 ＊ values before and after operation monthly for 4 timepoints.Also micro-computed tomography （micro-CT） and biochemical measurements were performed.The sensitivity of liver T2 ＊ relaxation time detecting early osteoporosis were estimated and the correlation between liver T2 ＊ values and BMD analyzed.Results BMD of lumber vertebra in OVX group decreased compared to control group at Month 2 postoperation （（554 ± 27） mg/cm3 vs （722 ± 19） mg/cm3,P ＜ 0.05） in synchrony with an elevation of serum ferritin concentration （（521 ± 41） ng/ml vs （441 ± 29） ng/ml,P ＜0.01） and liver iron concentration （（291 ± 18） μg/g vs （237 ± 27） μg/g,P ＜ 0.01）.A significant inter-group difference of liver T2 ＊ was detected at Month 1 postoperation （（13.2 ± 0.7） ms vs （13.9 ±0.4） ms,P ＜0.01）.Liver T2 ＊ was significant positively correlated with BMD in sham group （r =0.410,P＜0.01） and OVX group （r =0.434,P＜0.01）.Conclusion Liver T2＊ relaxation time may a valuable detection tool of assessing pathophysiological changes of osteoporosis in early stage.