In and Ex Vivo MR Evaluation of Acute Myocardial Ischemia in Pigs by Determining R1 in Steady State After the Administration of the Intravascular Contrast Agent NC100150 Injection

Abstract

Rationale and Objectives: To study the dose response in perfused and nonperfused myocardium by measuring relaxation rate (R1) in a steady-state situation after injection of the intravascular contrast agent NC100150 Injection in pigs and whether the dose response differs in vivo and ex vivo. Materials and Methods: The left anterior descending artery was occluded. R1 was measured using a Look-Locker sequence for 2 dose groups (2 mg Fe/kg bw, n = 4, and 5 mg Fe/kg bw, n = 5) and a control group (n = 3). Results: A significant increase in R1 was found in perfused myocardium after contrast agent injection, in contrast to nonperfused myocardium. There was a significantly larger difference in R1 between perfused and nonperfused myocardium in the 5 mg Fe/kg bw dose group compared with the other 2 groups. The difference in R1 between perfused and nonperfused myocardium was significantly higher in vivo than ex vivo. Conclusion: A nearly linear R1 dose response was found in perfused myocardium in vivo. The dose response ex vivo was less steep possibly due to larger water exchange limitations.