胰岛细胞移植磁共振扫描活体示踪的序列优化

Optimization of MRI scan sequence for tracking superparamagnetic iron oxide-labeled pancreatic islet ceils in vivo

背景:细胞移植领域仍缺乏有效的方法活体示踪观察细胞移植后体内的转归,随着分子影像学的发展使磁共振移植细胞活体示踪技术成为可能。目的:对胰岛细胞移植磁共振成像活体示踪的扫描序列和参数进行优化,提高胰岛细胞移植磁共振扫描活体示踪结果的可靠性。方法:通过SD大鼠门静脉输注超顺磁氧化铁纳米颗粒菲立磁标记的胰岛细胞,固定于7cm小动物专用线圈,在临床1.5TMR上分别采用SET1W、FSET2W、FGRE、SPGR对移植前后大鼠肝脏进行扫描,观察输注胰岛细胞前后研究部位的信号变化,并比较不同序列SPIO标记胰岛细胞与周围肝脏组织的对比度噪声比。结果与结论:FGRE和SPGR都可以较好地克服腹部呼吸运动伪影,敏感地显示超顺磁氧化铁纳米颗粒菲立磁标记的胰岛细胞。标记胰岛细胞在SD大鼠肝脏MRI图像上表现为斑点状的信号减低区,广泛分布于肝脏各部位。结果显示磁共振扫描可以对肝内胰岛移植物进行有效示踪,序列的选择至关重要。

BACKGROUND:There are no effective methods to track superparamagnetic iron oxide (SPIO)-labeled pancreatic islet cells in vivo. By the development of molecule imaging, it is possible to track SPIO-labeled islet cells in vivo using MRI. OBJECTIVE:To optimize MRI scan sequence for tracking SPIO-labeled pancreatic islet cells in rats using 1.5T MR scanner, and to set up optimize sequences of tracking and perfect measures of quality control. METHODS:MR imaging of transplanted cells were performed using a GE 1.5T Excite MRI scanner with a 7 cm animal coil. Different sequences such as SE T1WI, FSE T2WI, FGRE T2*WI and SPGR T1WI were applied. Contrast noise ratio of different sequences between SPIO and liver images of different sequences after SPIO-labeled pancreatic islet ceils were compared. RESULTS AND CONCLUSION:SPIO-labeled pancreatic islet cells were seen on MRI as distinct homogenous, low-signal spots in the liver. Better contrast between SPIO-labeled pancreatic islet cells and livers were gained in the images of FGRE T2* WI and SPGR T1WI sequences. The findings demonstrate that MRI can be used to track SPIO-labeled islet cells in vivo, and has significant value in detecting the survival and rejection of grafts after transplantation in rats. It’s very important to choose suitable sequences.