A Preliminary Study Of Cardiac Magnetic Resonance In The Diagnosis Of Myocardial Contusion

Objective:In this study,1.5T cardiac magnetic resonance(CMR)examination was performed on patients with blunt chest injury to preliminarily study the application value of cardiac magnetic resonance in the clinical diagnosis of myocardial contusion(MC).Method:In this study,patients with blunt chest injury who were treated by the Department of Cardiothoracic Surgery,Affiliated Hospital of Hangzhou Normal University from September 2018 to January 2021 were selected.42 patients were screened through inclusion and exclusion criteria.Twenty patients with cardiac troponin I(cTnⅠ)was increased(cTnⅠ>0.06ng/ml),which were classified as the cTnⅠ positive group;and twenty-two patients with normal cTnⅠ(cTnⅠ<0.06ng/ml),which were classified as the cTnⅠ-negative group.Both groups were examined by 1.5T CMR,and the CMR scanning plan included cine,T2-weighted short-tau inversion recovery(T2-STIR),T1 mapping sequence,T2 mapping sequence.The obtained image data is transferred to the background workstation for processing,and the results were analyzed and diagnosed by two cardiovascular MR doctors with more than 10 years.The consistent conclusion was obtained.If there is a difference of opinion,it will be resolved through negotiation.At the same time,cardiac troponin I(cTnⅠ),creatine kinase(CK),creatine kinase myocardial isozyme(CK-MB),electrocardiogram(ECG)and transthoracic echocardiography(TTE),which were routinely examined in both groups to collect and record the relevant data.Chi-square test or t-test was used to compare and analyze the correlation between CMR,myocardial injury markers,electrocardiogram,transthoracic echocardiography and myocardial contusion,and evaluate their clinical value.Result:(1)CMR examination of cTnⅠ positive group found 15 cases of innormal(15/20,75%)and 5 cases of normal(5/20,25%),CMR examination of cTnⅠ negative group found 2 cases of innormal(2/22,9%),20 cases of normal(20/22,91%).There is significant difference between the two groups(P < 0.001).(2)CMR scan abnormalities include myocardial edema,segmental ventricular wall motion abnormalities,myocardial ischemia or hemorrhage.17 cases of myocardial contusion,the left ventricle accounts for 12 cases(70.6%),and the right ventricle accounts for 5 cases(29.4%).The sensitivity(TPR),specificity(TNR)and positive predictive value(PPV)of CMR in the diagnosis of myocardial contusion were 75%,91% and 88.2%,respectively.(3)The myocardial injury markers(cardiac troponin I,creatine kinase,and creatine kinase isoenzyme)of the cTnⅠ positive group is higher than those of the cTnⅠ negative group.There is significant difference between the two groups(all P<0.05).(4)There are no significant difference in electrocardiogram and transthoracic echocardiogram between cTnⅠ positive group and cTnⅠ negative group(all P > 0.05).Conclusion:(1)Cardiac magnetic resonance can better reflect the imaging changes of myocardial contusion.It has high sensitivity and specificity in the diagnosis of myocardial contusion,which has important application value in early clinical diagnosis of myocardial contusion.(2)With the further development of research and the progress of magnetic resonance technology,cardiac magnetic resonance is likely to become one of the reliable criteria for the diagnosis of myocardial contusion.(3)cTnⅠ has a high specificity in the diagnosis of myocardial contusion.CK,CKMB and CK-MB/CK are not suitable to be used as diagnostic indicators of myocardial contusion alone.cTnⅠ combined with CK-MB/CK can improve the diagnosis rate of myocardial contusion.(4)The specificity of electrocardiograph and transthoracic echocardiography in the diagnosis of myocardial contusion are poor,and they are difficult to find mild or subendocardial myocardial contusion,which may have a certain reference for severe myocardial contusion.