儿童心肌炎MRI的诊断价值

Diagnostic value of cardiovascular magnetic resonance in children with myocarditis

目的：探讨心脏磁共振（CMR）在儿童心肌炎诊断中的价值。方法搜集2013年5月至2014年6月41例进行CMR检查患儿，其中27例临床诊断为心肌炎（心肌炎组），急性期16例、慢性期11例；非心肌炎患儿14例（非心肌炎组）。41例患儿采用稳态自由进动（SSFP）序列进行心脏横断面、左心室二腔心、四腔心以及短轴面扫描以评估心脏功能，然后分别进行左心室短轴面三反转恢复序列T2WI、早期增强（EGE）和延迟强化（LGE）序列扫描，计算T2WI和EGE序列上心肌骨骼肌信号比值及LGE阳性例数。定量资料因不符合正态分布，数据描述使用中位数和上下四分位数范围表示，统计方法采用Mann-Whitney非参数检验以及χ2检验。计算T2WI、EGE、LGE及“综合序列诊断”诊断心肌炎的敏感度、特异度及准确性。结果心肌炎组射血分数为60.20%（44.40%，70.20%），T2WI上心肌骨骼肌信号比为2.50（2.04，3.79），延迟强化（LGE）例数为13例；非心肌炎组对应的数值分别为73.60%（65.40%，75.85%）、1.85（1.77，2.15）和1例，两组间差异具有统计学意义（Z值分别为－2.94、－2.52，χ2=5.19，P值均〈0.05）。T2WI、EGE、LGE序列诊断心肌炎的敏感度分别为81.5%（22/27）、14.8%（4/27）、48.1%（13/27），特异度分别为57.1%（8/14）、100.0%（14/14）、92.9%（13/14），准确性分别为73.2％（30/41）、43.9%（18/41）和63.4%（26/41），综合序列诊断心肌炎的敏感度、特异度和准确性分别为51.9%（14/27）、92.9%（13/14）和65.9％（27/41）。结论心脏MRI是目前诊断儿童心肌炎重要的非创伤性检查方法，各扫描序列的综合评估可提高诊断的准确性。

Objective To determine the diagnostic value of cardiovascular magnetic resonance （CMR） in children with myocarditis. Methods A total of 27 children with myocarditis were examined with cardiac MRI, including 16 new-onset cases and 11 chronic cases, as well as 14 cases with non-myocarditis. Sequences included SSFP in axial, two chamber, four chamber and short axis, T2-weighted triple inversion recovery, T1-weighted spin echo before and after gadolinium injection, and inversion recovery-gradient echo after gadolinium injection（late gadolinium enhancement, LGE） in axial and short axis. Qualitative and quantitative image analysis was performed to obtain focal T2 signal intensity and early enhancement signal intensity（SI） ratio of myocardium to skeletal muscleon EGE and LGE.The sensitivity, specificity and accuracy were calculated. Mann-Whitney and χ2 test were used for statistical comparison. Results The median value of EF was 60.20%（44.40%,70.20%）, median value of T2W SI ratio was 2.50（2.04, 3.79）,and there were 13 cases with LGE positive findings in myocarditis group. The median value of EF was 73.60%（65.40%,75.85%）, the median value of T2WI SI ratio was 1.85（1.77, 2.15）, and one case presented LGE positive sign in non-myocarditis group. There were significant statistical differences between the two groups （Z=-2.94,-2.52 ,χ2=5.19 ,P〈0.05）. The sensitivities for T2WI, EGE, LGE were 81.5%（22/27）, 14.8%（4/27） and 48.1%（13/27） respectively. The specificities for T2WI, EGE, LGE were 57.1%（8/14）, 100.0%（14/14）and 92.9%（13/14） respectively. The diagnostic accuracies for T2WI, EGE, LGE were 73.2%（30/41）, 43.9%（18/41） and 63.4%（26/41） respectively. The best diagnostic performance was obtained when“any-two”of the three sequences were positive in the same patient, yielding a 51.9%（14/27）sensitivity, 92.9%（13/14） specificity, and 65.9%（27/41） diagnostic accuracy.Conclusions The combined CMR approach using T2-weighted imaging, early and late gadolinium enhancement, provides a high diagnostic accuracy and is a useful tool in the diagnosis and assessment of children with myocarditis.