Diagnostic value of myocardial perfusion imaging and delayed enhancement scan examination by cardiac magnetic resonance in children with viral myocarditis

Abstract

Objective To determine the diagnostic value of myocardial perfusion imaging and delayed enhancement scan examination by cardiac magnetic resonance(CMR) in children with viral myocarditis(VMC). Methods Twenty-eight children who had been diagnosed as VMC(18 male and 10 female; age range 5-16 years, and mean age 9.6 years) were chosen as the VMC group, 7 children with primary dilated cardiomyopathy(5 male and 2 female; age range 1.2-10.0 years, and mean age 6.2 years) were chosen as the group of DCM, and another 13 healthy children(8 male and 5 female; age range 6-12 years, and mean age 8.9 years) were chosen as the control group.Cardiac injury markers[cardiac troponin T(cTnT), creatine kinase-MB-mas(CK-MB-mas) and pro-brain natriuretic peptide(pro-BNP)], electrocardiogram, and transthoracic echocardiography were performed on all of the children before CMR imaging.All the children underwent CMR imaging, and the results of CMR was compared with cardiac injury markers, electrocardiograms and echocardiography.Five children with VMC re-examined CMR in recovery phase. Results Among the 28 VMC cases, 9 children were diagnosed as severe VMC and the rest 19 children were diagnosed as common VMC.The youngest children with VMC was 1.2 years old, and all the children were performed CMR imaging successfully and safely, and no adverse reaction to the contrast agent and other complications occurred.Heart rate of all the children were under 120 beats per minute, and the mean examination time was 40 min to an hour.Seven cases with dilated heart, 12 cases with regional thinning myocardium, 2 cases with thickening interventricular septum, 8 cases with reduced myocardial mobility, 4 cases with reduced left ventricular ejection fraction, 1 case with high signal in T2-weighted image, 17 cases showed delayed-enhancement, and the sensitivity of CMR delayed enhancement scanning in children received VMC was significantly higher than that in children with dilated cardiomyopathy(60.71% vs 0, P<0.01), and the sensitivity in severe VMC sensitivity was significantly higher than that of ordinary VMC(100.00% vs 42.11%, P<0.01). The specificity was 100% in VMC group.Five children received VMC re-examination CMR after their treatments, and 3 cases' delayed-enhancement signals disappeared while the other 2 cases' became weaker than before. Conclusions CMR is a safely and effectively noninvasive means to diagnose VMC.VMC performed expanded heart, regional thinning myocardium, reduced mobility, reduced left ventricular ejection fraction, high signal in T2 weighted imaging and delayed enhancement signal in CMR.The specificity of CMR delayed enhancement examination in severe VMC is higher than the sensitivity in ordinary VMC.CMR delayed enhancement examination could dynamically observe the changes in myocardial inflammation, and it can be used in the follow-up of VMC. Key words: Cardiac magnetic resonance; Viral myocarditis; Delayed enhancement scan; Child