Importance of perfusion in myocardial viability studies using delayed contrast‐enhanced magnetic resonance imaging

Abstract

Purpose: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. Materials and 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. Conclusion: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 inversionrecovery 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.

P846, a new gadolinium based low diffusion magnetic resonance contrast agent, in characterizing occlusive infarcts, reperfused ischemic myocardium and reperfused infarcts in rats

“…2, Table 2). These results agreed with data recently reported by Hedstrom et al using IR-GRE in a swine model of occlusive infarcts [31]. The core of the occlusive infarcts was hyperenhanced at 50 min after Gd-DOTA injection due to a shortening of T 1 .…”

Modeling of factors affecting late gadolinium enhancement kinetics in MRI of cardiac amyloid

“…The effective permeability-surface area product of the scar, PSs, will also likely be reduced, reflecting both a smaller net capillary surface area and an overall increased diffusion distance between capillaries and the tissue EES [ 12 , 16 ]. Note that “diffusion” in this context concerns contrast agent exchange on a tissue microscale of capillaries and the interstitial space between cells; Hedstrom [ 17 ] has shown that on a tissue macroscale, diffusion alone is not able to bring significant amounts of contrast agent into areas of myocardium without any perfusion. While specific values for these parameters are likely to be variable between patients (and even between different locations within a given patient), we can use the computer model to qualitatively assess the expected effects of different values of the parameters on the time course of the contrast enhancement.…”