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.
OBJECTIVE
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.


METHODS
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.


RESULTS
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.


CONCLUSIONS
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.
Flacke
Sebastian
S
Center for Cardiovascular Magnetic Resonance, Department of Medicine, Cardiovascular Division, Washington University Medical School, St Louis, MO, USA. flacke@uni-bonn.de
Allen
John S
JS
Chia
Jon M
JM
Wible
James H
JH
Periasamy
M Peri
MP
Adams
Max D
MD
Adzamli
I Kofi
IK
Lorenz
Christine H
CH
D000704:Analysis of Variance; D000818:Animals; D003287:Contrast Media / Q000493:pharmacokinetics*; D004195:Disease Models, Animal; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D017895:Manganese Compounds / Q000493:pharmacokinetics*; D009203:Myocardial Infarction / Q000175:diagnosis*; D009942:Organometallic Compounds / Q000493:pharmacokinetics*; D019047:Phantoms, Imaging; D051381:Rats; D017207:Rats, Sprague-Dawley
D003287:Contrast Media; D017895:Manganese Compounds; D009942:Organometallic Compounds; C112666:gadoversetamide