Delayed contrast-enhanced (DCE) long-axis image (left) demonstrating infarcted myocardium (MI). MR-labeled-MSC injections appear as hypointense areas on fast gradient echo images. Serial imaging at 72 hours, 1 week, 2 weeks, 4 weeks, and 8 weeks demonstrates the persistent of the MR-MSC injections. The volume of injections decreases over time. In addition, an injection placed in the normal myocardium (arrow) can no longer be detected at 4 weeks post-injection. Reprinted with permission from Soto et al..