磁共振成像在致心律不齐性右室型心肌病的诊断价值

目的回顾性分析27例致心律不齐性右室型心肌病（ARVC）的磁共振成像（MRI）表现,探讨MRI在ARVC的诊断与预后判断中的价值。方法按照1994年WHO关于ARVC的诊断标准,2004年10月至2006年6月共27例临床诊断或病理确诊为ARVC（6例行心脏移植术）,男21例,女6例,平均年龄37．4（15～67）岁。采用1．5T超导MRI扫描仪对心脏形态（脂肪浸润、房室大小）、功能（室壁局部与整体运动功能）、心肌灌注与心肌存活等方面进行综合评价。结果形态学：88．89％（24／27）的病例MRI提示心肌脂肪浸润,62．96％（17／27）右室壁变薄,62．96％（17／27）右室心尖肌小梁明显粗乱,66．67％（18／27）右室流出道扩张,51．85％（14／27）右室心尖扩张,66．67％（18／27）右室下壁及游离壁扩张,40．74％（11／27）合并右房增大。心脏功能：18．52％（5／27）的病例右室局部运动功能异常,70．37％（19／27）整体运动功能异常,右室平均射血分数（EF）35％。40．74％（11／27）的患者合并左室扩大并室壁收缩运动明显减弱。心肌首过灌注示10．52％（2／19）的患者左室受累,36．84％（7／19）的患者左室和右室壁出现异常强化,提示心肌纤维或胶原变性。右室壁强化区域主要位于右室游离壁和右室流出道肌壁,左室则主要位于左室侧壁,少数合并左室心尖或室间隔,5例左室侧壁异常强化经术后病理证实为纤维组织。仅1例表现为右室流出道增宽,但左室心肌显著变薄,收缩运动明显减弱;有3例右室MRI无阳性表现,其中2例左室侧壁室壁变薄并运动异常,延迟显像为异常强化,另1例表现为类似扩张型心肌病样改变。结论MRI高度的软组织对比与多序列成像可对ARVC进行全面诊断与预后评价,但少数以左室异常表现为主而无明显或仅轻微右室异常的病例,MRI易误诊,其左室侧壁段的纤维化为ARVC相对特征表现。右室整体运动异常、广泛纤维脂肪浸润、合并左室扩张并运动异常为其预后不良的指标。

Diagnostic value of magnetic resonance imaging for arrhythmogenic right ventricular cardiomyopathy

Objective To evaluate the diagnostic value of magnetic resonance imaging(MRI)for arrhythmogenic right ventricular cardiomyopathy(ARVC).Methods MRI was performed in 27(male 21,mean age:37.4 y,ranging from 15-67 y)clinically diagnosed ARVC patients according to the 1994 ARVC diagnosis criteria of WHO from Oct.2004 to Jun.2006.Heart chamber size,fat infiltration,local or global ventricular function,myocardium perfusion of contrast first pass and late enhancement were examined.Results Fat infiltration was found in 24(88.89%),trabecular disarray in 17(62.96%),significant dilated right ventricle outlet(RVOT)in 18(66.67%),dilated RV apex in 14(51.85%),dilated RV free wall and posterior wall in 18(66.67%)and right atrium enlargement in 11(40.74%)patients.Local RV dysfunction was found in 18.52%(5/27),global RV dysfunction in 70.37%(19/27)of patients with mean RV ejection fraction(EF)of 35%.Left ventricle was affected in 40.74%(11/27)of patients.Perfusion defects were found in only 10.52%(2/19)of patients.Positive late enhancement of myocardium were found in 36.84%(7/19)of patients and affecting mainly the wall of RVOT and the free wall associated with lateral wall enhancement of LV.Five patients received heart transplantation and histology on transplanted hearts confirmed the MRI findings.Conclusion "one-stop-shop" MRI scanning can be used for the diagnosis of ARVC.While for some ARVC cases with dominant abnormality in LV,it is difficult for MRI to differentiate ARVC from dilated cardiomyopathy or coronary heart disease.We found fibrosis of lateral wall of LV can be a characteristic sign of ARVC.