Determining canine myocardial area at risk with manganese-enhanced MR imaging.
OBJECTIVE
To test whether manganese-enhanced magnetic resonance (MR) imaging can safely depict the myocardial area at risk both during coronary artery occlusion and for at least 2 hours after reperfusion in dogs.


METHODS
All procedures were performed in accordance with the animal care and use committee of the National Institutes of Health. In eight dogs, the left anterior descending (LAD) coronary artery was occluded for 90 minutes, and 15 micromol of MnCl2 per kilogram of body weight was intravenously infused for 12 minutes. Phase-sensitive inversion-recovery MR imaging of the LAD arterial territory was performed before occlusion, during MnCl2 infusion, and for at least 2 hours after reperfusion. Hemodynamic responses were monitored continuously. Fluorescent microsphere enhancement was used as the reference standard for determining the area at risk ex vivo. Results are reported as percentages of left ventricular area. Correlation, Bland-Altman, and t test analyses were performed.


RESULTS
Significant differences in manganese-induced contrast enhancement of the area at risk, the normal myocardium, and the blood (P < .01) were measured during LAD artery occlusion and at least 2 hours after reperfusion. No significant changes in heart rate or blood pressure were detected during or after MnCl2 infusion. Measurements of the area at risk obtained with manganese-enhanced MR imaging during LAD artery occlusion and 2 hours after reperfusion correlated well with the size of the at-risk area demarcated by the fluorescent microspheres (during occlusion: y = 0.81x, R = 0.90; during reperfusion: y = 0.83x, R = 0.89). Bland-Altman analysis revealed small systematic errors in measurements at both occlusion and reperfusion.


CONCLUSIONS
Manganese-enhanced MR imaging can depict the area at risk during LAD artery occlusion and at least 2 hours after reperfusion without hemodynamic compromise.
Natanzon
Alex
A
Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, U.S. Department of Health and Human Services, 10 Center Dr, MSC 1061, Bldg 10, Room B1D-416, Bethesda, MD 20892-1061, USA.
Aletras
Anthony H
AH
Hsu
Li-Yueh
LY
Arai
Andrew E
AE
D000818:Animals; D002712:Chlorides; D003287:Contrast Media; D004285:Dogs; D006439:Hemodynamics / Q000187:drug effects; D007262:Infusions, Intravenous; D019028:Magnetic Resonance Imaging, Cine; D017895:Manganese Compounds; D017202:Myocardial Ischemia / Q000473:pathology*; D015425:Myocardial Reperfusion
D002712:Chlorides; D003287:Contrast Media; D017895:Manganese Compounds; C025340:manganese chloride