Importance of perfusion in myocardial viability studies using delayed contrast-enhanced magnetic resonance imaging.
OBJECTIVE
To investigate whether an extracellular gadolinium-(Gd)-based contrast agent (CA) enters nonperfused myocardium during acute coronary occlusion, and whether nonperfused myocardium presents as hyperintense in delayed contrast-enhanced (DE) MR images in the absence of CA in that region.


METHODS
The left anterior descending coronary artery (LAD) was occluded for 200 minutes in six pigs. The longitudinal relaxation rate (R(1)) in blood, perfused myocardium, and nonperfused myocardium was repeatedly measured using a Look-Locker sequence before and during the first hour after administration of Gd-DTPA-BMA.


RESULTS
While blood and perfused myocardium showed a major increase in R(1) after CA administration, nonperfused myocardium did not. R(1) in nonperfused myocardium was significantly lower than in blood and perfused myocardium during the first hour after CA administration. When the signal from perfused myocardium was nulled, demarcation of the hyperintense nonperfused myocardium was achieved in all of the study animals.


CONCLUSIONS
Gd-DTPA-BMA does not enter ischemic myocardium within one hour after administration during acute coronary occlusion. The ischemic region with complete absence of CA still appears bright when the signal from perfused myocardium is nulled using inversion-recovery DE-MRI. This finding is important for understanding the basic pathophysiology of inversion-recovery viability imaging, as well as for imaging of acute coronary syndromes.
Hedström
Erik
E
Department of Clinical Physiology, Lund University, Lund, Sweden. erik.hedstrom@med.iu.se
Arheden
Håkan
H
Eriksson
Rolf
R
Johansson
Lars
L
Ahlstrom
Håkan
H
Bjerner
Tomas
T
D000818:Animals; D003287:Contrast Media / Q000494:pharmacology; D003327:Coronary Disease / Q000473:pathology; D003331:Coronary Vessels / Q000473:pathology; D005260:Female; D005682:Gadolinium / Q000494:pharmacology; D007511:Ischemia / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009203:Myocardial Infarction / Q000473:pathology; D009206:Myocardium / Q000473:pathology*; D010477:Perfusion; D013552:Swine; D013997:Time Factors
D003287:Contrast Media; D005682:Gadolinium