Magnetic susceptibility of Dy-DTPA-BMA to reperfused myocardial infarction in an excised dog heart model: evidence of viable myocardium.

OBJECTIVE

To assess the effects of Dy-DTPA-BMA (sprodiamide) on ex-vivo MR imaging of reperfused acute myocardial infarction.

METHODS

Eighteen dogs were subjected to 2-hour coronary artery occlusion followed by 24-hour reperfusion. Dysprosium-chelate (Dy-DTPA-BMA) was injected into 16 dogs. Twenty minutes before their sacrifice. Two dogs did not receive the contrast medium and were used as controls. Excised hearts were imaged on T2-weighted spin-echo sequence (T2W SE) and T2*-weighted gradient recalled echo sequence (T2*W GRE), then sectioned and double-perfused for planimetric comparison.

RESULTS

Dy-DTPA-BMA induced myocardial signal loss was detected on T2W SE and on T2*W GRE images. The signal loss was observed at the subendocardial location of the myocardial wall inducing an apparent enlargement of the left ventricle cavity and a thinning appearance of the anterior myocardial wall.

CONCLUSIONS

Myocyte necrosis diminishes the potency of dysprosium to cause MR imaging signal intensity loss in reperfused myocardial infarction. Pre-infarcted myocardium with potentially reversible viability may be responsible for the effect of the contrast medium.