Normal and infarcted myocardium: differentiation with cellular uptake of manganese at MR imaging in a rat model

• Published in: Radiology Vol. 216; no. 2; p. 524
• Main Authors: Bremerich, J, Saeed, M, Arheden, H, Higgins, C B, Wendland, M F
• Format: Journal Article
• Language: English
• Published: United States 01-08-2000
• Subjects: Analysis of Variance; Animals; Contrast Media; Coronary Disease - complications; Disease Models, Animal; Dose-Response Relationship, Drug; Echo-Planar Imaging; Edetic Acid - administration & dosage; Edetic Acid - analogs & derivatives; Edetic Acid - blood; Female; Follow-Up Studies; Magnetic Resonance Imaging - methods; Manganese - administration & dosage; Manganese - blood; Manganese - pharmacokinetics; Metabolic Clearance Rate; Myocardial Infarction - etiology; Myocardial Infarction - metabolism; Myocardial Reperfusion; Myocardium - metabolism; Pyridoxal Phosphate - administration & dosage; Pyridoxal Phosphate - analogs & derivatives; Pyridoxal Phosphate - blood; Rats; Rats, Sprague-Dawley
• ISSN: 0033-8419
• DOI: 10.1148/radiology.216.2.r00jl14524

To assess whether normal myocardium can be distinguished from infarction at magnetic resonance (MR) imaging with low doses of manganese dipyridoxyl diphosphate (Mn-DPDP).
After 1-hour coronary arterial occlusion and 2-hour reperfusion, three groups of eight rats each were injected with 25, 50, or 100 micromol of Mn-DPDP per kilogram of body weight. The longitudinal relaxation rate (R1) in normal myocardium, reperfused infarction, and blood was repeatedly measured at inversion-recovery echo-planar imaging before and for 1 hour after the administration of contrast material. Afterward, several animals from each group were examined at high-spatial-resolution inversion-recovery spin-echo (SE) MR imaging.
Manganese accumulated in normal myocardium but was cleared from reperfused infarction and blood. One hour after the administration of Mn-DPDP, R1 in normal myocardium (1.53 sec(-1) +/- 0.03, 1.73 sec(-1) +/- 0.03, and 1.94 sec(-1) +/- 0.02, respectively, for 25, 50, and 100 micromol/kg) was significantly (P <.05) faster than that of reperfused infarction (0.99 sec(-1) +/- 0.03, 1.11 sec(-1) +/- 0.03, and 1.48 sec(-1) +/- 0.06). Normal myocardium appeared hyperintense on T1-weighted inversion-recovery SE MR images and was clearly distinguishable from reperfused infarction.
Mn-DPDP-enhanced inversion-recovery echo-planar and SE MR images demonstrated retention of manganese in normal myocardium and clearance of manganese from infarction. Mn-DPDP has characteristics similar to those of widely used thallium and may be useful in the assessment of myocardial viability at MR imaging.