地中海贫血患者心脏、肝脏铁沉积的MRI定量研究

The relationship between heart and liver iron in thalassemia： a quantitative analysis using MRI

目的定量评价地中海贫血患者心脏、肝脏铁沉积程度，探讨两者关系及临床用肝铁浓度〉15mg／g干重预测心铁沉积的准确性。方法连续搜集2010年9月至2011年6月期间103例5岁以上总输血（全血）剂量〉10U（1U=200m1）地中海贫血患者资料，行心脏、肝脏MR检查并测量T2＊值，采用Spearman秩相关分析其相关性。以肝脏T2＊〈0．96ms（相当于肝铁浓度〉15mg／g干重）为标准，将患者分为两组，采用秩和检验比较各组心肌T2＊值的差异。以心脏T2〈10ms、10ms≤T2＊〈20InS和T2＊≥20ms为标准，将患者分为3组并采用秩和检验比较各组肝脏T2＊值有无差异。绘制用肝铁浓度〉15mg／g干重预测患者心脏铁沉积的ROC曲线。结果103例地中海贫血患者的心脏T2＊值中位数为24．00ms（4．70～51．10ms），肝脏T2＊值中位数为1．16ms（0．68～14．80Ills），两者呈低度相关（r=0．453，P=0．000），且未见规律性。肝脏T2＊〈0．96ms组25例患者的心脏T2＊值中位数为12．10ms（4．70～41．70ms），T2＊〉／0．961TIS组78例患者的心脏T2＊值中位数为26．10ms（4．80～51．10ms），两组之间差异有统计学意义（Z=-3．566，P=0．000）。心脏T2＊〈10ms组20例患者的肝脏T2＊值中位数为1．06I／IS（0．68～3．83ms），T2＊≥20ms组58例患者中位数为1．76ms（0．74～14．80ms），差异有统计学意义（Z=-3．553，P=0．000）；10ms≤T2＊〈20ms组25例患者的肝脏T2＊值中位数为0．99ms（0．69～13．59ms），与T2＊〉20ms组间差异有统计学意义（Z=-3．951，P=0．000）；心脏T2。〈10ms组与10ms≤T2＊〈20ms组相比，两组患者的肝脏T2＊值之间差异无统计学意义（z=-0．046，P=0．964）。以肝铁浓度〉15mg／g干重预测心脏铁沉积的ROC曲线下面积为0．771，敏感度为42．2％，特异度为89．7％。结论多次输血地中海贫血患者的心、肝铁水平之间呈低度相关。肝铁浓度〉15mg／g干重的患者心铁沉积发生率相对较高，用其预测心脏铁沉积的准确度为中等偏低。

Objective To quantify the heart and liver iron overload in thalassemia patients and discuss the relationship of iron deposition between them, and to evaluate the accuracy of using hepatic iron concentration 〉 15 mg/g dry tissue as an index to predict heart iron deposition as used in clinical practice. Methods One hundred and three transfusion-dependent patients with thalassemia, who were older than 5 years, underwent MRI heart and liver t to obtain T： ＊ values. The Spearman rank correlation was employed to analyze the relationship between cardiac T2 ＊ and liver T2 ＊ values. By using liver T2 ＊ = 0. 96 ms as standard setting, patients were divided into two groups, and the differences of cardiac T2 ＊ values between the two groups were compared by Wilcoxon rank sum test. Then by using cardiac T2 ＊ = 10, 20 ms as standard setting, patients were divided into 3 groups, and the differences of liver T2 ＊ values among the3 groups were compared by Wilcoxon rank sum test. The ROC curves were drawn to predict the possibility of using hepatic iron concentration 〉 15 mg/g dry tissue as an index of cardiac iron deposition. Results The cardiac and liver T2 ＊ values of the 103 thalassemia patients showed low correlation （ r = 0. 453, P = 0. 000）. With the liver T2 ＊ value reduced, the cardiac T2 ~ value did not decline proportionally. The cardiac T2 ＊ value range and median of 25 patients＇ group whose liver T2 ＊ 〈0. 96 ms were 4. 70 to 41.70 ms and 12. 10 ms, respectively. The cardiac T2 ＊ value range and the median of 78 patients＇ group whose liver T2 ＂ 〉 0. 96 ms were 4. 80 to 51.10 ms and 26. 10 ms, respectively. There was statistically significant difference between those of the two groups（Z = -3. 566, P = 0. 000）. The liver T2 ＊ value range and the median of 20 patients＇group whose cardiac T2 ＊ 〈 10 ms was 0. 68 to 3.83 ms and 1.06 ms, respectively. The liver T2 ~ value range and the median of 58 patients＇ group whose cardiac T2 ＊ 〉120 ms were 0. 74 to 14. 80 ms and 1.76 ms, respectively. There was statistical difference between those of the two groups（Z = -3. 553,P =0. 000）. The liver T2 ＊ value range and the median of 25 patients＇ group with cardiac 10 ms~〈 Tz ＊ 〈20 ms were 0. 69 to 13. 59 ms and 0. 99 ms, respectively. The values were significantly different from that of Tz＊ ~〉20 ms group（Z = -3.951,P =0.000）. The liver T2 ＊ values of cardiac T2 ＊ 〈 10 ms group was not statistically different from that of 10 ms~〈T2 ＊ 〈20 ms group（Z = -0. 0d6,P =0. 964）. To predict cardiac iron deposition with the index of hepatic iron concentration 〉 15 mg/g dry tissue, the area under the ROC curve was 0. 771. The sensibility was 42. 2%, the specificity was 89. 7%. Conclusions There is low correlation between heart and liver iron level in thalassemia patients with long-term transfusions. Patients with hepatic iron concentration 〉 15 mg/g dry tissue have a higher incidence of heart iron deposition, but the accuracy of using hepatic iron concentration as an index to predict myocardial iron deposition is low to moderate.