Characterization of viable and nonviable myocardium at MR imaging: comparison of gadolinium-based extracellular and blood pool contrast materials versus manganese-based contrast materials in a rat myocardial infarction model

• Published in: Radiology Vol. 226; no. 3; p. 731
• Main Authors: Flacke, Sebastian, Allen, John S, Chia, Jon M, Wible, James H, Periasamy, M Peri, Adams, Max D, Adzamli, I Kofi, Lorenz, Christine H
• Format: Journal Article
• Language: English
• Published: United States 01.03.2003
• Subjects: Analysis of Variance; Animals; Contrast Media - pharmacokinetics; Disease Models, Animal; Magnetic Resonance Imaging - methods; Male; Manganese Compounds - pharmacokinetics; Myocardial Infarction - diagnosis; Organometallic Compounds - pharmacokinetics; Phantoms, Imaging; Rats; Rats, Sprague-Dawley
• ISSN: 0033-8419
• DOI: 10.1148/radiol.2263020151

To determine the contrast agent behavior of gadolinium-based (extracellular and albumin-binding) and manganese-based contrast media for late-enhancement imaging of myocardial infarction. Coronary ligation was performed in 30 rats, and they were serially imaged with segmented inversion-recovery gradient-echo magnetic resonance (MR) imaging (repetition time msec/echo time msec/inversion time msec [fixed], 5.2/2.5/430; flip angle, 15 degrees ) during 1 hour after administration of contrast media by using a 1.5-T MR unit. Serial measurements of the longitudinal relaxation were performed by using the Look-Locker approach (repetition time msec/echo time msec, 1,000/3.5; flip angle, 10 degrees ). Detection and size of infarction were evaluated at each time point and compared with end-point histologic findings. For all manganese-based media, the contrast agent cleared from the blood pool rapidly. Manganese-based contrast media allowed precise labeling of viable cardiomyocytes within 30 minutes, and the labeling persisted for at least 1 hour. Accumulation of gadoversetamide in the infarct area was apparent after 5 minutes, and the peak contrast-to-noise ratio (CNR) between infarct and myocardium was comparable to the peak CNR of manganese-based contrast agents. Extracellular gadopentetate dimeglumine provided excellent infarct detection but a small imaging window for precise sizing of the infarct if a fixed inversion time of 430 msec was used. Albumin-binding gadolinium-based contrast media provided a longer imaging window, but infarct size was overestimated because of the nonspecific distribution of the unbound gadolinium agent. When extracellular gadolinium-based agents are used for infarct size measurement, imaging parameters and timing are important because the kinetics of both normal and irreversibly injured myocardium must be considered. Manganese-based agents are highly specific and less sensitive to timing for infarct size determination, but further studies are required to determine if they are feasible for human use.