心脏磁共振心肌灌注和延迟增强扫描对儿童病毒性心肌炎的诊断价值

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

目的 探讨心脏磁共振（CMR）心肌灌注和延迟增强扫描对儿童病毒性心肌炎（VMC）的诊断价值.方法 选择28例VMC患儿作为VMC组,其中男18例,女10例;年龄5～16岁,平均9.6岁.7例原发性扩张型心肌病患儿作为扩心组,其中男5例,女2例;年龄1.2～10.0岁,平均6.2岁;同时选择13例健康儿童作为健康对照组,其中男8例,女5例;年龄6～12岁,平均8.9岁.所有儿童先抽取外周血检测肌钙蛋白T、肌酸激酶同工酶质量、N端脑钠肽前体,行心电图和经胸超声心动图检查.然后在急性期完成CMR检查,将CMR结果与心肌损伤标志物、心电图、超声心动图结果对比,5例VMC患儿于恢复期复查CMR,并将结果与急性期CMR结果进行对比.结果 患儿中年龄最小者为1.2岁,均顺利完成CMR检查,无一例出现对比剂过敏及其他并发症,心率在120次/min以下,平均检查时间为40 min ～1 h.其中重症VMC9例,普通VMC19例.VMC组心腔扩大者7例,局部心肌变薄者12例,室间隔心肌增厚者2例,心肌动度减低者8例,左心室射血分数（LVEF）减低者4例,T2加权像出现高信号者1例,出现心肌延迟强化者17例.CMR延迟增强扫描在VMC组的敏感度明显高于扩心组（60.71％比0,P＜0.01）,并且对重症VMC的敏感度明显高于普通VMC（100.00％比42.11％,P＜0.01）,特异度均为100％.5例患儿分别于急性期和恢复期行CMR,其中3例患儿恢复期CMR延迟期强化信号消失,2例患儿延迟期强化信号强度较急性期减弱,范围较急性期减小.结论 CMR是儿童VMC安全有效的无创性检查手段.VMC在CMR上表现为心脏扩大,局部心肌变薄、动度减低,LVEF减低,延迟增强扫描时病灶区出现强化信号是其特异性表现,延迟增强扫描对重症VMC敏感度高于对普通VMC的敏感度,并具有较高的特异度.CMR心肌延迟增强扫描可以动态观察心肌炎症的变化,可用于病情随访.

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.