纽约（路透社健康版）－据11月21日《美国心脏病学会杂志》报道，联合使用血管内和细胞外造影剂的MRI可鉴别急性心肌梗死（MI）和陈旧性心肌梗死或瘢痕。
旧金山加利福尼亚大学的Maythem Saeed 博士和他的同事们在同一动物身上制造3天MI和8周MI模型，检验血管内钆螯合剂区分急性和陈旧性性MI的能力。结果发现，给予血管内和细胞外钆螯合剂后，所有急性梗死的心肌都出现延迟增强，而陈旧性梗死未出现增强。
作者解释说，标准的细胞外钆螯合剂造影增强不能区分急性和陈旧性MI，但是血管内给予钆螯合剂在急性MI出现延迟增强，而陈旧MI不会出现此现象。不论是急性梗死，还是陈旧性梗死，血管内或细胞外给予钆螯合剂都不会使血压或动脉血氧饱和度发生显著变化。
研究者认为，血管内钆螯合剂可以区分急性MI和陈旧瘢痕组织，但不包括以下情况：1）新的急性梗死发生已有梗死的部位，或存在缺血性心肌病。2）已发生心肌梗死的患者行血管成形术的术中或术后梗死。
“如果给予钆螯合剂后没有延迟增强，那么就不是急性梗死。对于缺血性心肌病患者，标准的细胞外造影剂也能区分坏死心肌与顿抑心肌及冬眠心肌。”作者总结说。
MRI discriminates new myocardial infarction from old infarct scar
11/28/2006
By: Reuters Health
http://www.auntminnie.com/index.asp?Sec=sup&Sub=car&Pag=dis&ItemId=73757
NEW YORK (Reuters Health) - MRI using a combination of intravascular and extracellular contrast media can distinguish between acute myocardial infarction (MI) and chronic infarctions or scars, according to a report in the November 21st issue of the Journal of the American College of Cardiology.
Standard extracellular gadolinium (Gd)-chelates contrast enhancement cannot distinguish acute from chronic MI, the authors explain, but intravascular Gd-chelates may produce delayed contrast enhancement of acute but not old MI.
Dr. Maythem Saeed from the University of California, San Francisco, and colleagues examined the potential of intravascular Gd-chelates in discriminating acute from chronic MI in an animal model of 3-day-old and 8-week-old MI.
All acutely infarcted hearts showed delayed enhancement after administration of intravascular and extracellular Gd-chelates, the authors report. In contrast, intravascular Gd-chelate failed to enhance chronic infarctions.
Neither intravascular nor extracellular administration of Gd-chelate caused significant changes in blood pressure or arterial oxygen saturation in either the acute or chronic infarction setting, the researchers note.
"The capability of distinguishing acute MIs from scar tissue by intravascular Gd-chelate might be useful for excluding: 1) a new acute infarction in the clinical setting of known prior infarction or in the presence of ischemic cardiomyopathy, and 2) intraoperative or postoperative infarction in a patient with known prior infarction after revascularization," the investigators suggest.
"If there is no delayed enhancement after administration of intravascular Gd-chelates, it is not an acute infarction," the authors conclude. "Standard extracellular agents would also be preferable for discriminating nonviable from stunning and hibernating myocardium in cases of ischemic cardiomyopathy."
Last Updated: 2006-11-28 14:36:00 -0400 (Reuters Health)
J Am Coll Cardiol 2006;48:1961-1968.
编辑：蓝色幻想
