磁粒子标记大鼠骨髓基质细胞的体外磁共振成像实验研究

MRI Study of Bone Marrow Stromal Cells of Rats Labeled with Magnetic Particle in Vitro

目的探讨标记细胞不同细胞数量所引起的MR信号强度变化规律，以及MR示踪最敏感的成像序列，为标记细胞活体内MR示踪奠定基础。方法用1％的琼脂糖混悬经Brdu和SPIO双标记的BMSCs（分别为2×106、1×106、5×105个）和未标记的BMSCs（2×106个），分别置于不同EP管中，行冠状位和轴位TSE序列T1WI、T2WI和FFE—T2WI扫描，测量相同细胞数量不同成像序列以及相同成像序列不同细胞数量的MR信号强度，并比较信号强度变化百分率。结果标记组5×105、1×106、2×106个细胞不同扫描序列MR信号强度变化百分率分别为，TSE—T1WI：（-4．19±0．788）％、（-16．35±1．228）％、（-22．80±1．053）％；TSE—T2WI：（-14．15±1．366）％、（-35．09±1．391）％、（-53．02±1．299）％；FFE—T2WI：（-44．98±0．456）％、（-69．38±0．820）％、（-87．24±0．818）％。同一扫描序列中各标记细胞组之间以及相同标记细胞数量各成像序列之间两两比较，差异均有统计学意义（P〈0．001）。结论磁粒子标记BMSCs，细胞浓度相同条件下，以FFE-T2WI序列信号下降最为明显，标记的细胞数量越多，信号改变越明显，呈细胞数量依赖性。FFE—T2WI序列为磁粒子标记细胞MR示踪的理想序列。

Objective To discuss the changes of MR signal intensity of different numbers of labeled BMSCs and the most sensitive sequences of MR tracing after stromal cells were labeled with magnetic particle to establish the foundation for MR tracing in vivo.Methods BMSCs which were labeled with Brdu and SPIO and that which were not labeled were suspended with 1% agarose solutions.The subjects were divided into four groups and put into different EP ducts,including 2×106 labeled cells,1.0×106 labeled cells,5×105 labeled cells and 2×106 unlabeled cells.MR scanning sequences included coronal and axial TSE-T1WI,TSE-T2WI and FFE- T2WI.Signal intensity of different sequences of the same object were measured and the MR signal intensity changing rate were compared.Results The MR signal intensity changing rate of BMSCs which 5×105,1 ×106 and 2 ×106 were labeled were as follows：TSE-TiWI：（-4.19 ± 0.788）%,（-16.35 ± 1.228）%,（-22.80 ± 1.053）% respectively;TSE-T2WI：（-14.15 ± 1.366）%,（-35.09 ± 1.391）%,（-53.02 ± 1.299）% respectively;FFE-T2WI：（-44.98 ± 0.456）%,（-69.38 ± 0.820）%,（-87.24 ± 0.818）% respectively.There were significant differences among labeled cells groups（P〈0.001） and significant differences among MRI sequences（P〈0.001）.Conelusion The signal intensity changes of FFE-T2WI sequence is the most apparent when the BMSCs which were labeled with magnetic particle were in the same concentration,and with the number of the labeled ceils increasing,the signal intensity changes were more visible.FFE-T2WI sequence was the ideal sequence for MR tracing of cells labeled with magnetic particle.