[Presentation and quantification of acute myocardial infarct using antibody-bound MR contrast medium]

A magnetically labeled antimyosin (MION-AM) has previously been developed for immunospecific MR imaging in vivo. The current study was designed to extend previous feasibility studies and to correlate MR infarct size to that determined by histopathology. The left anterior coronary artery (LAD) was temporarily occluded in rabbits (n = 10) and subsequently reperfused for 1 h prior to the administration of 100 mumol Fe/kg of MION-AM (corresponding to 0.5 mg AM). One hour after i.v. administration, the infarcted myocardium appeared hypointense by MRI as a result of target-specific attachment of the magnetic T2 label to damaged but not normal myocardium. There was a close correlation between infarct size determined by MR and pathology (SE 2500/30: r = 0.92, p < or = 0.0001; SE 2500/60: r = 0.85, p < or = 0.0001). Our results are evidence that a) immunospecific magnetic probes can be utilized for cardiac MR imaging, and b) that these or similar agents may aid in the quantitation of myocardial infarct size.