Canine Acute Myocardial Infarction In Vivo Detection by MRI with Gradient Echo Technique and Contribution of Gd-DOTA
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This experimental study was designed to evaluate the sensitivity of MRI in the detection of acute myocardial infarction, determine the utility of fast gradient-echo (GE) imaging and study possible improvements in diagnostic efficacy using a paramagnetic contrast agent (gadolinium-DOTA). Myocardial infarcts were induced in 11 dogs by semidistal embolization and imaged using spin-echo and/or GE pulse sequences, short TRs (250 to 450 ms) and cardiac gating. After the dogs died, the heart was imaged under the same conditions as in vivo. Blind comparisons between precontrast, postcontrast (0.1 mM/kg and 0.5 mM/kg), postmortem images and anatomic findings (triphenyl-tetrazolium-chloride staining) were recorded. This study shows that infarcted areas can be detected on plain MRI images in the form of a hypersignal, probably attributable to increased proton density, with better efficiency of GE compared with spin-echo imaging; injection of gadolinium-DOTA allows better delineation of infarcted areas, especially for 10 minutes after administration.
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