Purpose: This study compared 3 different contrast agents for magnetic resonance imaging (MRI) to determine whether their rate of permeability could discriminate between acutely rejecting and nonrejecting transplanted hearts.
Materials and methods: Heterotopic heart transplantation in rats was performed and animals were divided into allogeneic and syngeneic groups. At the sixth postoperative day, MRI was performed with 2 ultrasmall superparamagnetic iron oxide particles of different sizes, unformulated NC 100150 and AMI-227, besides gadodiamide.
Results: For unformulated NC100150, the signal intensity between the groups differed at all times (P < 0.0001); for AMI-227, all times but 3 (P < 0.05). With low molecular weight gadolinium chelate, no discrimination between rejecting and nonrejecting groups could be made.
Conclusion: Acutely rejecting and nonrejecting transplanted hearts can be discriminated from each other using the difference in permeability assessed by blood pool agents and MRI. With first pass of gadolinium chelate no discrimination could be made between rejecting and nonrejecting grafts.