Reperfused Myocardial Infarction as Seen with Use of Necrosis-specific versus Standard Extracellular MR Contrast Media in Rats

Abstract

The sizes of hyperenhanced regions displayed by using mesoporphyrin and gadopentetate dimeglumine differed from each other. The difference in size of the hyperenhanced region demarcated by mesoporphyrin and gadopentetate dimeglumine may provide an estimation of potentially salvageable myocardium.

Magnetic Resonance Characterization of the Peri-Infarction Zone of Reperfused Myocardial Infarction With Necrosis-Specific and Extracellular Nonspecific Contrast Media

“…In contrast to a previous report, 14 the present study used moderate myocardial injury to create a sizable peri-infarction zone. Multiphase spin-echo MR imaging was used to characterize regional wall thickening.…”

“…Overestimation of the infarct size by Gd-DTPA confirms previously published data in occlusive and reperfused infarctions. [12][13][14] The difference in the enhanced regions demarcated by the agents may represent the periinfarction zone. Functional MR imaging confirmed that the outer rim of the Gd-DTPA-enhanced zone (peri-infarction zone) is hypokinetic rather than akinetic, whereas the mesoporphyrin-enhanced region is entirely akinetic.…”

“…The imaging parameters have been described previously. 14 SI values were normalized to SI of Gd-DTPA phantom (T1ϭ1.1 seconds), which was included in each image acquisition. Heterogeneity in vascular distribution resulted in a high degree of intersubject variability in the injured area after coronary occlusion.…”

“…[5][6][7][8][9][10][11][12][13][14] Extracellular MR contrast media such as Gd-DTPA are passively distributed into the interstitium from intact capillaries in normal myocardium. Disruption of cellular membrane, expansion of interstitium, and increased blood volume provide an expanded distribution volume for these agents.…”

“…Disruption of cellular membrane, expansion of interstitium, and increased blood volume provide an expanded distribution volume for these agents. Several studies [12][13][14] have indicated that nonspecific extracellular contrast media overestimate infarct size, suggesting that the enhanced region encompasses both viable and nonviable portions. Until recently, the peri-infarction zone has not been mapped and characterized with a single technique because of spatial or contrast-resolution constraints of available imaging techniques.…”