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 micromol/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.