Manganese dipyridoxyl-diphosphate (MnDPDP) as a viability marker in patients with myocardial infarction

Purpose: To evaluate contrast accumulation in left ventricular (LV) myocardium after manganese dipyridoxyl-diphosphate (MnDPDP) administration in patients with recent first time myocardial infarction. Materials and Methods: MnDPDP (5 mu mol/kg) was administered to 10 patients with recent myocardial infarction (three to 12 weeks). One slice of interest (SOI) likely to traverse the infarction was chosen, and sectorial pre- and postcontrast longitudinal relaxivity rates (R-1) and signal changes during infusion were estimated with a fast gradient echo sequence. LV volume and wall thickening were measured in short-axis cine recordings, Infarct localization from R-1 and wall thickening data were compared by vector analyses. Results: Reduced wall thickening was associated with reduced precontrast R-1 and reduced contrast enhancement. Both remote and infarcted regions showed rapid initial contrast accumulation. In remote regions, this was followed by a continuing slow increase. Mean precontrast R-1 was 0.87 +/- 0.06 second(-1) in infarcted regions and 0.96 +/- 0.03 second(-1) in remote regions (P < 0.001). Mean R-1 change over one hour was 0.24 +/- 0.07 second(-1) in infarcted regions and 0.38 +/- 0.03 second(-1) in remote regions (P < 0.0001). Conclusion: Remote regions showed larger increases in R-1 than infarcted regions. This is most likely due to selective and slow Mn accumulation in viable myocytes.