Infarcted myocardium in pigs: MR imaging enhanced with slow-interstitial-diffusion gadolinium compound P760

PURPOSE: To assess the value of P760, a gadolinium chelate with slow inters titial diffusion and high relaxivity, fdr magnetic resonance (MR) imaging o f acute myocardial infarction in pigs. MATERIALS AND METHODS: First-pass gradient-echo MR imaging and spin-echo MR imaging were performed with P760 and then with gadoterate meglumine in eig ht pigs with occlusive acute myocardial infarction. P760 signal intensity e nhancement and clearance were compared with those of gadoterate meglumine. RESULTS: The first-pass enhancement ratio of P760 in normal myocardium was higher than that in infarcted myocardium (1.37 +/- 0.06 [SEM] vs 1.05 +/- 0 .03, P = .03). The myocardial first pass showed a blood pool-like curve for P760. The blood pool enhancement ratio 40 seconds after injection was high er for P760 than for gadoterate meglumine (left ventricular cavity, 1.75 +/ - 0.06 vs 1.45 +/- 0.06, P = .009). Spin-echo MR imaging showed improved co ntrast between normal and infarcted myocardium after P760 administration: T he ratio before contrast material administration was 0.21 +/- 0.03, that at 15 minutes was 0.48 +/- 0.05 (P = .002), and that at 25 minutes was 0.47 /- 0.07 (P = .003). CONCLUSION: P760 is an MR imaging contrast agent characterized by low diffu sion, a blood pool effect soon after low-dose administration, and fast elim ination. This agent is useful for improved myocardial perfusion MR imaging of acute myocardial infarction.