首过及延迟增强的磁共振成像技术在心肌梗死中的价值

The role of first pass and delayed contrast-enhancement magnetic resonance imaging in patients with myocardial infarction

目的评价造影剂增强的磁共振成像技术在心肌梗死中的作用。方法共有23例患者入选,经过动态观察患者的症状、心电图和心肌酶谱,有20例患者确诊为心肌梗死,所有患者都完成冠状动脉造影和造影剂增强的磁共振检查。结果20例患者在造影剂增强的磁共振成像时,梗死部位首过显示为低强化区,延迟增强时显示为高强化区,测定梗死面积为(16·58±9·73)%,梗死面积与肌酸激酶峰值、肌钙蛋白T峰值有明显相关性(分别R=0·821,P<0·01和R=0·565,P<0·05)。磁共振成像测定的射血分数为0·46±0·13,左室造影测定的左室射血分数为0·49±0·16,两者差异无统计学意义,也没有相关性。结论造影剂增强的磁共振成像对心肌梗死起到明确诊断和判断预后的重要作用。

Objective To evaluate the role of contrast-enhancement magnetic resonance imaging （CeMRI） in patients with myocardial infarction （MI）. Methods There were twenty-three patients enrolled in this study. After dynamic observation, there were 20 patients who were diagnosed as MI. All those patients underwent coronary artery angiography and CeMRI. MRI was performed with a 1.5-T magnet （AVANTO, SIMENS）. After tagged images were acquired, the patients received an intravenous bolus of 0. 1 mmol/kg Gd-DTPA at a rate of 5 ml/s. A first-pass perfusion scan was acquired simultaneously with a bolus injection. A second bolus of 0. 3 mmol/kg Gd-DTPA was given following the first-pass images. Delayed images were acquired 5 minutes after the second bolus by using an inversion-recovery prepared gated fast-gradient echo-pulse sequence. Results Hypoenhancement was seen in 20 patients at the first-pass perfusion at the myocardial infarction site, while hyperenhancement was seen at delayed CeMRI. Myocardial infarction area in delayed CeMRI was 16. 58% ± 9. 73%, which was correlated positively with peak CK and cTnT （ r = 0. 821, P 〈 0. 01 and r = 0. 565, P 〈 0. 05）, respectively. The ejection fraction （EF） detected by MRI was 0. 46 ±0. 13 ,while the left ventricular EF （LVEF） detected by left ventriculography was 0. 49 ± 0. 16. There was no difference between two parameters. Conclusion CeMRI may play an important role in the diagnosis and prognosis of patients with MI.