心肌梗死模型家猪存活心肌的磁共振延迟成像评价

背景：心脏磁共振延迟成像被认为是极有前景的无创性判断心肌存活状态的影像检查手段。目前常用的对比剂Gd-DTPA存在过高或过低评价存活心肌和不可逆性梗死心肌,而坏死亲和性对比剂ECIII-600可以准确地反映坏死心肌的面积。目的：对比冠脉内注射坏死亲和性对比剂在猪再灌注急性心肌梗死存活心肌诊断中的应用价值。方法：三四个月龄普通家猪12头,建立急性再灌注心肌梗死动物模型,分别冠脉内注射0.1 mmol/kg Gd-DTPA或 0.005 mmol/kg ECIII-600。胸导R波触发心电门控,T1加权FAST序列,短轴面延迟强化扫描成像。扫描结束后沿短轴面将心脏切成6 mm断面行氯化三苯基四氮唑染色和光镜检查。比较相应层面的MRI延迟强化区和氯化三苯基四氮唑染色所示梗死区的关系。结果与结论：注射Gd-DTPA的延迟成像10 min时强化区面积与氯化三苯基四氮唑染色相比过高估计梗死心肌面积约21%,30 min时强化区面积与氯化三苯基四氮唑染色结果一致,之后则过低估计坏死心肌的面积;注射ECIII-600的延迟磁共振成像在坏死区显示强烈而持续的对比增强,强化区面积与氯化三苯基四氮唑染色所示心肌梗死面积一致。说明ECIII-600增强磁共振延迟成像可以准确反映急性心肌梗死面积。Gd-DTPA评价心肌梗死面积不稳定,观察时间窗短,心脏磁共振成像应在对比剂注射后1 h以内完成。

Delayed magnetic resonance imaging for survived myocardium in pigs with myocardial infarction

BACKGROUND: Delayed cardiac magnetic resonance imaging (MRI) is considered to be a promising noninvasive imaging to determine myocardial viability status. The commonly used contrast agent Gd-DTPA evaluation of survival myocardium is rather too high or too low, and irreversibility of myocardial infarction, but necrosis affinity contrast ECIII-600 can accurately reflect the area of necrotic myocardium. OBJECTIVE: To compare the diagnosis value of intracoronary injection of contrast medium affinity necrosis in evaluating myocardial viability in pigs with acute myocardial infarction.METHODS: Twelve pigs were prepared for acute myocardial infarction models and were intracoronary injected 0.1 mmol/kg Gd-DTPA or 0.005 mmol/kg ECIII-600. Chest leads of ECG R wave trigger control, T1-weighted sequence with FAST, and delayed enhancement short axis surface scan imaging were performed. After scanning, the heart was cut along the short axis plane line into 6 mm sections and examined by triphenyl tetrazolium chloride (TTC) staining and light microscope. Relationship between infarct areas at the corresponding layer of MRI delayed enhancement and TTC staining was compared. RESULTS AND CONCLUSION: Compared with TTC staining of myocardial infarction, the injection of Gd-DTPA enhanced delayed imaging 21% overestimated the infarcted area at 10 minutes, which was correspondence with the TTC staining at 30 minutes, followed by underestimation of the size of myocardial necrosis; Injection ECIII-600 MRI in the delayed necrosis showed strong and sustained contrast enhancement, strengthening area of myocardial infarction with TTC staining showed the same area. ECIII-600-enhanced MRI can accurately reflect the delay in acute myocardial infarct size. Gd-DTPA evaluation of myocardial infarct size is instable, and the observation time window is short. The cardiac MRI contrast agent should be completed within 1 hour after injection.