Abstract:

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.