DOUBLE-CONTRAST MR-IMAGING OF REPERFUSED PORCINE MYOCARDIAL-INFARCTION - AN EXPERIMENTAL-STUDY USING GD-DTPA-BMA AND DY-DTPA-BMA

Purpose: Myocardial infarctions were induced in 12 pigs to investigate whether a double-contrast method, combining a positive and a negative MR contrast agent, could improve the visualization of reperfused myoc ardial infarctions. Material and Methods: All 12 pigs were subjected t o 80 min of occlusion followed by reperfusion. In the double-contrast group (6 pigs), Gd-DTPA-BMA (0.3 mmol/kg b.w.) and Dy-DTPA-BMA (1.0 mm ol/kg b.w.) were administered i.v. after 30 min of reperfusion. In the remaining 6 pigs, a single injection of Gd-DTPA-BMA (0.3 mmol/kg b.w. ) was given after 30 min of reperfusion. All pigs were sacrificed 10 m in postcontrast injection, corresponding to a reperfusion time of 40 m in. The hearts were excised and imaged with MR. The concentrations of Gd and Dy were measured in infarcted and nonischaemic myocardium using ICP-AES. Results and Conclusion: Contrast media concentrations were m ore than 4-fold higher in infarcted compared with nonischaemic myocard ium. The infarctions were best shown on T1-weighted images, and there were no differences between the double and single contrast groups. In the T2-weighted images, the infarctions were significantly better visu alized in the double-contrast group, due to a Dy-induced signal intens ity loss in nonischaemic myocardium.