| Objective:The purpose of this study is to explore the feasibility of quantitative detection of myocardial fibrosis in old myocardial infarction by T1 mapping.To evaluate the clinical value of T1 mapping in the diagnosis of myocardial fibrosis in patients with old myocardial infarction.Methods:From June 2019 to December 2020,thirty patients with old myocardial infarction diagnosed by the Department of Cardiac surgery of Handan Central Hospital in Hebei Province(case group)were selected,and forty healthy volunteers were recruited in the same period(control group).Routine sequence,T1 mapping and late gadolinium enhancement sequence were performed in the case group.Routine sequence and T1mapping sequence were performed in the control group.Get the image and import it into Medis Suite software for processing.With late gadolinium enhancement as the gold standard,the infarcted myocardial segments with positive late gadolinium enhancement in the case group and the anterior septum,inferior septum and lateral wall of normal myocardium in healthy volunteers were measured on the short axis of the heart,and the myocardial Native T1 values of the case group and the control group were obtained respectively.The infarcted myocardium of patients with old myocardial infarction was manually sketched on late gadolinium enhancement and T1mapping sequence,and the average infarct size and transmurality were calculated respectively.Student’s T-test was used to compare the corresponding segments at different levels of left ventricle in healthy volunteers.One-way ANOVA was used to compare different segments at the same level.Student’s T-test was used to compare the Native T1 values of infarcted myocardium in the case group and normal myocardium in the control group.Rank sum test was used to compare the average infarct size and transmurality measured by late gadolinium enhancement and T1mapping sequence.Linear regression and Bland-Altman analysis was used to compare the correlation and consistency between mean infarct size and transmurality measured by two techniques.Results:1.The Native T1 values of 2,3,5,8,9,11 segments were obtained(1236.5±17.3),(1231.1±19.7),(1219.6±23.7),(1234.1±16.7),(1229.1±21.7),(1213.0±20.5)ms.The value of Native T1 in the segments 2,3,8,9 was higher than that in the 5 and 11 segment,and the difference was statistically significant(P<0.05).There was no significant difference in myocardial Native T1 values between segments 2 and 8,3 and 9,5 and 11(P>0.05).2.In this study,the Native T1 value of infarcted myocardium in the case group was(1428.1±62.9)ms.Compared with healthy volunteer’s different coronary blood supply areas,there were significant differences in myocardial Native T1 values(P<0.001).3.Native T1 mapping were not difference for measuring infarct size(LGE:11.1±7.9%;T1:11.2±8.1%,P>0.05),and were in agreement with LGE(R~2=0.96,Bias=-0.09±1.5%).Native T1 mapping were not difference for measuring infarct transmurality(LGE:35.4±16.8%;T1:36.2±17.9%,P>0.05)and were in agreement with LGE(R~2=0.92,Bias=-0.75±4.9%).Conclusions:1.In this study,the ranges of Native T1 values of different left ventricular myocardial segments in healthy volunteers and patients with old myocardial infarction were obtained,which provided reference value for related clinical studies.2.There are differences in myocardial Native T1values in different regions of the left ventricle,which may be related to the factors of blood perfusion.3.T1 mapping can identify and quantitatively evaluate myocardial fibrosis in patients with old myocardial infarction.4.Native T1 mapping can accurately characterize the infarct size and transmurality of infarcted myocardium,so Native T1 mapping can be used as an alternative for patients with late gadolinium enhancement taboos. |
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