地中海贫血患者肝脏T2*、血清铁蛋白预测心肌铁过载价值研究

Value of liver T2* and SF to predict myocardial iron concentration patients with thalassemia

目的定量评估地中海贫血(thalassemia,TM)患者心肌和肝脏铁沉积,探讨肝脏T2*、血清铁蛋白(serum ferritin,SF)预测心铁过载价值。材料与方法应用3.0 T磁共振梯度多回波序列扫描基因确诊并满足要求的地中海贫血患者113例,测量其心肌和肝脏T2*值,所有受试者扫描前后7 d、间隔1 w实验室两次检测血清铁蛋白。对心肌T2*、肝脏T2*、SF分度诊断并应用秩相关分析3者间的关系,采用受试者工作特征曲线(receiver operating characteristic curve,ROC曲线),评价肝脏T2*<0.70 ms、SF>2500μg/L时预测心铁过载及SF>300μg/L预测肝铁过载诊断效能及最佳阈值。结果 113例TM患者的铁沉积分度诊断如下:心肌正常94例,轻度6例,中度10例,重度3例;肝脏正常13例,轻度31例,中度29例,重度25例,极重度15例;血清铁蛋白正常1例,轻度48例,中度17例,重度35例,极重度12例。秩相关分析显示心肌T2*-肝脏T2*(r_s=0.267,P=0.004)、心肌T2*-SF(r_s=-0.63,P=0.000)、肝脏T2*-SF(r_s=-0.641,P=0.000)三者间轻中度相关但无规律性。以心肌T2*<10 ms诊断心铁沉积异常,肝脏T2*<0.70 ms、SF>2500μg/L预测心铁过载准确性分别为0.788和0.833,敏感度分别为80.0%、73.3%,特异性分别为70.4%、63.3%;以肝脏T2*<3.57 ms诊断肝铁过载,SF>300μg/L预测肝铁过载ROC曲线下面积为0.719,敏感度为94.0%,特异性为15.4%。结论在一定范围内,MRI T2*扫描可直接定量体内器官铁沉积,心铁过载、肝铁沉积、SF三者间轻中度相关但无规律性;以肝脏T2*、血清铁蛋白预测心肌铁异常价值较低,而血清铁蛋白预测肝铁过载尚不可靠。

Objective：To quantify the MIC, liver iron concentration （LIC） in TM patients and discuss the value of liver T2＊, SF to predict the MIC.Materials and Methods：Study protocol was approved by local ethics committee; informed consent was obtained. A total of 113 TM patients diagnosed by gene were enrolled. A multiple fast-field echo （mFFE） within a single breath-hold was performed using a 3.0 Tesla MR unit to acquire 8 or 12 T2＊ weighted images in the heart or liver. T2＊values of myocardium and liver were quantiifed based on mFFE T2＊ protocol by a well-trained physician respectively, SF was obtained twice within 7 days before and after MRI. Spearman rank correlation was applied to analyze the relationships among the MIC, LIC and SF. The ROC curve was drawn to predict the possibility of using liver T2＊＆lt;0.70 ms, SF＆gt;2500μg/L as an index of cardiac iron deposition, and the possibility of using SF＆gt;300μg/L as an index of liver iron overload.Results：A total of 113 patients, the grades of body iron deposition as following： nineteen out of 113 were found to have myocardial excess iron, including 3 severe cases, 10 moderate cases, and 6 mild cases; 100 out of 113 were found to be liver excess iron, including 15 very severe cases, 25 severe cases, 29 moderate cases, and 31 mild cases; 112 out of 113 patients were found to be abnormal SF, including 12 very severe cases, 35 severe cases, 17 moderate cases, and 48 mild cases. There was weakly or moderate correlation between myocardial T2＊ and liver T2＊ （rs=0.267,P=0.004）, myocardial T2＊ and SF （rs=-0.463,P=0.000）, as well as between liver T2＊and SF （rs=-0.641,P=0.000）, but no clear regularity. To predict cardiac iron deposition with myocardial T2＊＆lt;10 ms as diagnostic criteria, the accuracies, sensibilities and speciifcities were 76.9%, 75% and 77.1% for the index of liver T2＊＆lt;0.70 ms, 82.7%, 68.8% and 68.6% for SF＆gt;2500 μg/L, respectively. Moreover, to predict liver excess iron with liver T2＊＆lt;3.57 ms as standard setting, the accuracy, sensibility and speciifcity were respectively 80.2%, 92.4% and 20.7% for the index of SF＆gt;2500 μg/L.Conclusion：Within a certain limits, MRI T2＊ technique could directly quantify the MIC and LIC, there was weakly or moderate correlation among MIC, LIC and SF, but no clear regularity. Using LIC or SF as an indirect index to predict cardiac excess iron were low valuable, meanwhile, using SF to predict liver iron overload was not reliable in clinical.