MRI assessment of ischemic liver after intraportal islet transplantation.

Background—There is a recent focus on embolization of the portal vein by transplanted islets as a major cause of early graft loss. The resultant ischemia causes necrosis and/or apoptosis of cells within the liver. Thus, non-invasive assessment of the liver receiving the islet transplant is important to evaluate the status islet grafts. Methods—In this study, we utilized non-invasive magnetic resonance imaging (MRI) for assessment of the post-transplant ischemic liver. Syngeneic islets in streprozotocin-induced diabetic mice were utilized. MRI and morphological liver assessments were performed at 0, 2, and 28 days after transplantation. Histological assessment of insulin, hypoxia induced factor 1-α and apoptosis were undertaken at similar time-points. Results—Ischemic/necrotic regions in the liver were detected with MRI at 2 but not at 28 days after transplantation and were confirmed histologically. Liver injury was quantified from high intensity areas on T2-weighted images. Insulin release showed a peak 2 days after transplantation. Conclusion—Onset and reversal of liver ischemia due to intraportal islet transplantation are detectable using T2-weighted MRI. These changes coincide with periods of maximum insulin release likely due to partial islet destruction. We propose that MRI, as a noninvasive monitor of graft-related ischemia, may be useful in assessment of liver and islet engraftment after intraportal islet transplantation in a clinical setting.