Manganese enhanced magnetic resonance imaging of normal and ischemic canine heart

The ability of MnCl 2 to enhance canine myocardium and to delineate ischemic areas is demonstrated. A dose–response curve was measured using T 1 weighted images in 11 dogs. MnCl 2 (36, 113, 360, and 3600 μmol) was infused over a period of 3 min. Signal intensity increased linearly with MnCl 2 dose. At 113 μmol (∼10 μmol/kg) the steady‐state increase in intensity averaged 212 ± 34%. No significant physiologic effects due to the infused MnCl 2 were detected except at the highest dose where there was a cardiac depressive effect. Ischemia was induced by occluding the left anterior descending coronary artery in 5 dogs. At an infused dose of 113 μmol, MnCl 2 clearly demarcated the ischemic zone during coronary occlusion. Contrast enhancement in the ischemic zone was less than 30% compared with normal tissue ( P < 0.03). In conclusion, the intracellular contrast agent MnCl 2 enhances the canine heart and shows promise in detecting ischemia at doses that do not cause adverse cardiac effects. Magn Reson Med 54:196–200, 2005. Published 2005 Wiley‐Liss, Inc.