中文摘要：

背景：目前关于超顺磁性氧化铁在进行细胞标记和作为网状内皮细胞系统特异性对比剂时对周围质子驰豫时间影响的报道差异较大。目的：验证超顺磁性氧化铁在细胞内外对磁共振信号的影响有否差异,以选择最佳的磁共振扫描方法。设计、时间及地点：对比观察,细胞成像实验,于2006-06/2007-01在川北医学院附属医院医学影像研究所和风湿免疫研究所完成。材料：超顺磁性氧化铁采用Resovist（SHU555A）,由德国先灵公司惠赠。将大鼠骨髓基质干细胞用铁质量浓度分别为0,4.2,8.4,21,42,84mg/L的氧化铁-多聚赖氨酸复合物标记。方法：应用GE Signa EXCITE 1.5TMR扫描仪对19只含不同质量浓度超顺磁性氧化铁的EP管及不同质量浓度铁标记后的磁标记细胞悬液进行体外MR成像。主要观察指标：超顺磁性氧化铁在不同磁共振序列上随质量浓度改变其信号改变的规律;低质量浓度时细胞内外超顺磁性氧化铁对磁共振信号影响的差异。结果：①在细胞外：T1WI信号强度随超顺磁性氧化铁质量浓度的增加先升高后降低,在T2WI上随质量浓度的增加信号降低,在低质量浓度时,T1WI及T2＊WI较T2WI更敏感,以T2＊WI最敏感（P〈0.05）。②在细胞内：MR信号强度随培养液中铁质量浓度的增加而增加,在FSET1WI,铁质量浓度≤21mg/L时,各组间信号强度没有显著性差异,当质量浓度为42mg/L和84mg/L时信号强度较对照组明显升高（P〈0.05）。在FSPGR T1WI,当铁质量浓度≥8.4mg/L时,各管信号强度明显高于对照管（P〈0.05）。在FSE T2WI及GRE T2＊WI上,当质量浓度为4.2mg/L时,信号强度较对照管信号强度明显降低（P〈0.05）,且T2＊WI信号降低较T2WI明显（P〈0.05）。结论：低质量浓度的超顺磁性氧化铁在细胞内外对MR信号的影响是不同的,T2＊WI为检测超顺磁性氧化铁较敏感而特异的序列。

英文摘要：

BACKGROUND： There are significant differences in the impact of superparamagnetic iron oxide （SPIO） as magnetic resonance （MR） contrast agent to relaxation rate. OBJECTIVE： To explore whether there are differences in the influence of intracellular and extracellular SPIO on the patterns of MR signal intensity, and to determine the optimal protocol of magnetic resonance imaging. DESIGN, TIME AND SETTING： Comparative observation and cell imaging trial. The experiment was performed in Imaging Research Institute and Department of Immunology of North Sichuan Medical College Hospital from June 2006 to January 2007. MATERIALS： Resovist （SHU555A） SPIO was graciously provided by （Schering AG, Germany）. Rat bone marrow stromal stem cells were labeled with iron oxide （iron mass concentration 0, 4.2, 8.4, 21, 42, and 84 mg/L） and polylysine. METHODS： MR imaging was performed on the Eppendoff tubes filled with SPIO of different concentrations using GE Signa EXCITE 1.5T MR scanner. MAIN OUTCOME MEASURES： Signal change rules of SPIO on different MR sequences; different influences of intracellular and extracellular SPIO on the patterns of MR signal intensity. RESULTS： Extracellular patterns： The signal intensity of the Eppendoff tubes increased first and then decreased following the increasing concentrations of SPIO on T1 weighted image （T1WI）, while the signal intensity decreased on T2 weighted images （T2WI）. The changes of signal intensity on T1WI and T2＊WI were more significant than on T2WI, especially on T2＊WI （P 〈 0.05）. Intracellular patterns： The signal intensity of the culture medium increased following the iron concentration increasing. There were no significant differences in signal intensity on fast spin echo TIWI when iron concentration ≤ 21 mg/L, while when iron concentration was 42 and 84 mg/L, the signal intensity was significantly increased compared to the control group （P 〈 0.05）. The signal intensity on fast spoiled gradient recalled echo