Differentiation of acute and four-week old myocardial infarct with Gd(ABE-DTTA)-enhanced CMR.
BACKGROUND
Standard extracellular cardiovascular magnetic resonance (CMR) contrast agents (CA) do not provide differentiation between acute and older myocardial infarcts (MI). The purpose of this study was to develop a method for differentiation between acute and older myocardial infarct using myocardial late-enhancement (LE) CMR by a new, low molecular weight contrast agent.Dogs (n = 6) were studied in a closed-chest, reperfused, double myocardial infarct model. Myocardial infarcts were generated by occluding the Left Anterior Descending (LAD) coronary artery with an angioplasty balloon for 180 min, and four weeks later occluding the Left Circumflex (LCx) coronary artery for 180 min. LE images were obtained on day 3 and day 4 after second myocardial infarct, using Gd(DTPA) (standard extracellular contrast agent) and Gd(ABE-DTTA) (new, low molecular weight contrast agent), respectively. Triphenyltetrazolium chloride (TTC) histomorphometry validated existence and location of infarcts. Hematoxylin-eosin and Masson's trichrome staining provided histologic evaluation of infarcts.


RESULTS
Gd(ABE-DTTA) or Gd(DTPA) highlighted the acute infarct, whereas the four-week old infarct was visualized by Gd(DTPA), but not by Gd(ABE-DTTA). With Gd(ABE-DTTA), the mean +/- SD signal intensity enhancement (SIE) was 366 +/- 166% and 24 +/- 59% in the acute infarct and the four-week old infarct, respectively (P < 0.05). The latter did not differ significantly from signal intensity in healthy myocardium (P = NS). Gd(DTPA) produced signal intensity enhancements which were similar in acute (431 +/- 124%) and four-week old infarcts (400 +/- 124%, P = NS), and not statistically different from the Gd(ABE-DTTA)-induced SIE in acute infarct. The existence and localization of both infarcts were confirmed by triphenyltetrazolium chloride (TTC). Histologic evaluation demonstrated coagulation necrosis, inflammation, and multiple foci of calcification in the four day old infarct, while the late subacute infarct showed granulation tissue and early collagen deposition.


CONCLUSIONS
Late enhancement CMR with separate administrations of standard extracellular contrast agent, Gd(DTPA), and the new low molecular weight contrast agent, Gd(ABE-DTTA), differentiates between acute and late subacute infarct in a reperfused, double infarct, canine model.
Kirschner
Robert
R
Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, MCLM 556, Birmingham, AL 35294-0005, USA.
Toth
Levente
L
Varga-Szemes
Akos
A
Simor
Tamas
T
Suranyi
Pal
P
Kiss
Pal
P
Ruzsics
Balazs
B
Toth
Attila
A
Baker
Robert
R
Brott
Brigitta C
BC
Litovsky
Silvio
S
Elgavish
Ada
A
Elgavish
Gabriel A
GA
D000818:Animals; D003287:Contrast Media; D003937:Diagnosis, Differential; D004195:Disease Models, Animal; D004285:Dogs; D019786:Gadolinium DTPA; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009203:Myocardial Infarction / Q000175:diagnosis*; D009206:Myocardium / Q000473:pathology*; D009942:Organometallic Compounds; D004369:Pentetic Acid; D011237:Predictive Value of Tests; D013997:Time Factors
D003287:Contrast Media; D009942:Organometallic Compounds; C120791:gadolinium N-(2-butyryloxyethyl)-N'-(2-ethyloxyethyl)-N,N'-bis(N'',N''-bis(carboxymethyl)acetamido)-1,2-ethanediamine; D004369:Pentetic Acid; D019786:Gadolinium DTPA