Interventional real-time molecular MRI for targeting early myocardial injury in a pig model.

Myocardial ischemia induces tissue injury with subsequent inflammation and recruitment of immune cells. Besides myocardial tissue characterization, magnetic resonance imaging (MRI) allows for functional assessment using molecular imaging contrast agents. Here, we assessed ischemic cardiac lesions non-invasively directly after ischemia/reperfusion (I/R) in a porcine model by advanced MRI techniques and molecular imaging, targeting the cell adhesion molecule P-selectin functionalized with microparticles of iron oxide (MPIO). We used a closed-chest model of I/R by temporary coronary balloon-occlusion, real time 3T MRI-guided coronary injection of MPIO-based contrast agents, as well as injury, edema and iron-sensitive MRI. Within the first hours after I/R, we found T1 mapping to be most sensitive for tissue injury, with no changes in edema-sensitive MRI. Intriguingly, P-selectin MPIO contrast agent selectively enhanced the ischemic area in iron-sensitive MRI. In conclusion, this approach allows for sensitive detection of early myocardial inflammation beyond traditional edema-sensitive imaging.