磁共振心肌灌注成像评价心肌梗死PTCA治疗前后心肌存活

Magnetic resonance myocardial perfusion imaging for evaluating myocardial viability after myocardial infarction

目的评价磁共振心肌灌注成像(MRMPI)检测心肌梗死存活心肌的作用。方法选择心肌梗死患者51例。采用1.5T MR扫描仪,反转恢复快速小角度激励(IR-turbo FLASH)序列,全部患者均在静脉注射钆喷替酸葡甲胺(Gd-DTPA)0.1mmol/kg、MRMPI首过期及5～30min延迟期成像。21例行静息、负荷99锝单光子发射计算机体层摄影术(single photon emission computed tomography,SPECT)进行对照研究。首过期行短轴面成像,延迟期行短轴面及长轴面成像。结果51例心肌梗死患者,42例(82.3%)首过期显示灌注减低;50例(98%)延迟增强。在21例168个心肌段SPECT诊断无活性心肌段48个,MRMPI示梗死区均有延迟增强,SPECT诊断存活心肌段120个,MRMPI示97段无延迟增强。以静息、负荷99m锝SPECT作为参考标准,MRMPI的敏感度、特异度分别为100%、80.8%。结论MRMPI可有效地检测心肌梗死的存活和非存活心肌,以及其程度和范围。

Objective To assess the value of magnetic resonance （MR） myocardial perfusion imaging （MRMPI） in evaluating the myocardial viability in patients with myocardial infarction. Methods MRMPI was performed in 51 patients with myocardial infarction using a 1.5 T MR scanner. All the patients were examined using IR-turbo FLASH sequence during the first-pass and delayed phase 5-30 min after injection of 0.1 mmol/kg Gd-DTPA at the rate of 4 ml/s. The short axis images were acquired during the first-pass, and both the short axis and long axis images were obtained during the delayed phase. The left ventricular wall on the short-axis slice was divided into 8 segments. A correlative study of the results of the rest and stress ^99mTc single photon emission computed tomography （SPECT） was carried out in 21 patients. Results In the 51 patients with myocardial infarction, 42 （82.3%） showed hypoperfusion during the first-pass imaging and 50 （98%） had delayed hyperenhancement. In the 21 patients receiving SPECT, 48 nonviable segments was detected among the 168 segments scanned by ^99mTcSPECT, and MRMPI showed delayed hyperenhancement in all the infracted areas. Of the 120 viable segments detected by rest and stress ^99mTc SPECT, 97 segments （80.8%） were found to be free of delayed hyperenhancement by MRMPI. With the rest and stress ^99mTc SPECT as the reference, the sensitivity and the specificity of MRMPI were 100.0% and 80.8%, respectively. Conclusion MRMPI allows effective identification of the myocardial viability and nonviability as well as the severity and extent of the myocardial infraction.