Magnetic Resonance Imaging of Acute Myocardial Ischemia Using a Manganese Chelate, Mn-DPDP

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Abstract
Pomeroy OH, Wendland M, Wagner S, Derugin N, Holt WW, Rocklage SM, Quay S, Higgins CB. Magnetic resonance imaging of acute myocardial ischemia using a manganese chelate, Mn- DPDP. Invest Radiol 1989;24:531–536. Nine adult rats underwent occlusion of the left coronary artery (LCA) to assess the ability of a manganese chelate of N, N'-Bis (pyridoxal-5-phosphate) ethylenediamine-N, N'-diacetic acid (Mn-DPDP), to delineate acute myocardial ischemia. Hemodynamic effects of the contrast medium were tested in the isolated rat heart. Gated transaxial images of the heart at the mid-ventricular level were obtained using a 2 Tesla magnet. A TE of 20 msec and a TR of 1 R-R interval (≈250 msec) were used. Images were taken prior to injection of 400μmol/kg of Mn-DPDP, 2 minutes after injection, and then at 15 minute intervals for one hour. The time between LCA occlusion and injection of contrast averaged 95 minutes. The signal intensity (SI) of normal myocardium was increased by 125 ± 9% immediately after injection, and did not significantly vary over one hour. SI of ischemic myocardium increased by only 16 ± 14% immediately after injection, gradually rising to 44 ± 13% after one hour. Visual discrimination between normal and ischemic myocardium was obtained throughout the study. The percent contrast between normal and ischemic myocardium was 47.2 ± 6% at 2 minutes after injection, gradually decreasing to a final value of 31.3 ± 4%. No hemodynamic effects were produced in the isolated heart using concentrations in the perfusate several-fold higher than those expected to be produced by the intravenous injection of 400 µmol/kg Mn-DPDP. Mn-DPDP shows the potential for delineation of the jeopardy area resulting from coronary occlusion for at least one hour after injection of the agent.