Quantitative assessment of salvaged myocardial zone and intramyocardial hemorrhage using non-contrast faster T2 mapping in a rat model by 7T MRI

Abstract

The aim of this study was to determine the myocardial area at risk (AAR), infarction-core size (IS) and the salvaged myocardial zone (SMZ), and to evaluate the imaging and histological characteristics of intramyocardial hemorrhage (IMH) after myocardial infarction using non-contrast T2 mapping on 7T magnetic resonance imaging (MRI). Twenty Sprague Dawley (SD) rats were randomly divided into the sham and model groups (n=10 in each). In the model group, myocardial infarction models were established by left anterior descending branch ligation. After 24 h, all animals were imaged on a 7.0 Tesla system with cine spiral imaging, T2 mapping with late gadolinium enhancement (LGE). The rats were then sacrificed for measurement of the IS and AAR using 2,3,5-triphenylterazolium chloride (TTC) and hematoxylin and eosin (H&E) staining. T2 mapping revealed that the AAR in the model group was significantly higher than that in the sham group. No remarkable T2 value was noted in the entire heart of the sham group. LGE and TTC staining demonstrated similar IS. T2 mapping and H&E staining revealed a similar AAR as well. T2 mapping characterized the IMH as a phenomenon resulting from the area of hypointensity in the hyperintensity involving the infarct-core zone and corresponding T2 value 928.6±1.52 msec with IMH vs. 35.8±2.61 msec without IMH; n=3 with 18 slices; P=0.032). In conclusion, non-contrast T2 mapping was a reliable approach to quantitatively evaluate the SMZ and IMH.

Emerging methods for the characterization of ischemic heart disease: ultrafast Doppler angiography, micro-CT, photon-counting CT, novel MRI and PET techniques, and artificial intelligence

“…Despite these limitations, recent literature demonstrates that the use of 7-T systems, either as small bore for experimental research or large bore for human applications, has potential in certain fields of cardiovascular imaging. Zhang et al [ 70 ] investigated and found T2 mapping feasible and reliable at 7 T to characterize myocardium in order to quantify the area at risk, infarct core, intramyocardial hemorrhage, and salvaged myocardial zone in a rat model of myocardial infarction. Spath et al [ 71 ] tested the application of manganese-enhanced MRI in a rat model of myocardial infarction.…”