Ryan T, Tarver R D, Duerk J L, Sawada S G, Hollenkamp N C
Krannert Institute of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis 46202.
J Am Coll Cardiol. 1990 May;15(6):1355-64. doi: 10.1016/s0735-1097(10)80026-9.
Early reperfusion has the potential for salvaging ischemic myocardium at risk for infarction. To test the ability of nuclear magnetic resonance (NMR) imaging to differentiate between stunned and infarcted myocardium early after reperfusion, 16 mongrel dogs underwent transient occlusion of the left anterior descending artery or a diagonal branch for 30, 60 or 180 min followed by reperfusion. To identify the area at risk for infarction and to assess the extent of hypoperfusion and reperfusion, two-dimensional and contrast echocardiography were performed at baseline study, during coronary occlusion and at three separate times during reperfusion (before NMR imaging, immediately after NMR imaging and 12 to 14 h later). Wall thickening in the control and ischemic zones and the circumferential extent of abnormal wall motion were analyzed at each time point using short-axis echocardiograms. Nuclear magnetic resonance imaging at 1.5 tesla was performed 2 to 3.5 h (mean 2.7 +/- 0.5) after reperfusion. Short-axis, multislice spin-echo images (TE 26 and TE 60) were obtained. Signal intensity was measured in the control and ischemic areas and expressed as a percent difference compared with normal myocardium. All dogs demonstrated a significant decrease in wall thickening and abnormal wall motion before and after NMR imaging. Seven of the eight dogs with infarction had an area of increased signal intensity on TE 60 images. The mean percent difference in signal intensity compared with adjacent normal myocardium was 127 +/- 68% (p = 0.002). None of the eight dogs without infarction had a visually apparent change in signal intensity on TE 60 images (mean percent difference versus control area 13 +/- 11%), despite regional systolic dysfunction documented by echocardiography at the time of imaging. The area of increased signal intensity correlated with infarct size (r = 0.69), although overestimation by NMR imaging occurred. The area of increased signal intensity did not correlate with the extent of echocardiographic contrast defect during coronary occlusion (risk area). This study demonstrates that NMR imaging can be applied early after coronary reperfusion to assess the potential for recovery of dysfunctional myocardium. In addition, by using a TE 60 multislice spin-echo imaging sequence at 1.5 tesla, quantification of the extent of infarction also may be possible.
早期再灌注有可能挽救有梗死风险的缺血心肌。为了测试核磁共振（NMR）成像在再灌注后早期区分顿抑心肌和梗死心肌的能力，16只杂种犬接受了左前降支或对角支短暂闭塞30、60或180分钟，随后进行再灌注。为了确定梗死风险区域并评估灌注不足和再灌注的程度，在基线研究、冠状动脉闭塞期间以及再灌注期间的三个不同时间点（在NMR成像前、NMR成像后立即以及12至14小时后）进行二维和对比超声心动图检查。使用短轴超声心动图在每个时间点分析对照区和缺血区的室壁增厚以及室壁运动异常的圆周范围。在再灌注后2至3.5小时（平均2.7±0.5小时）进行1.5特斯拉的核磁共振成像。获得短轴多层自旋回波图像（TE 26和TE 60）。在对照区和缺血区测量信号强度，并表示为与正常心肌相比的百分比差异。所有犬在NMR成像前后均表现出室壁增厚和室壁运动异常显著降低。8只梗死犬中有7只在TE 60图像上有信号强度增加的区域。与相邻正常心肌相比，信号强度的平均百分比差异为127±68%（p = 0.002）。8只无梗死的犬在TE 60图像上均未出现明显的信号强度变化（与对照区的平均百分比差异为13±11%），尽管在成像时超声心动图记录了局部收缩功能障碍。信号强度增加的区域与梗死面积相关（r = 0.69），尽管NMR成像存在高估。信号强度增加的区域与冠状动脉闭塞期间超声心动图对比缺损的范围（风险区域）无关。本研究表明，NMR成像可在冠状动脉再灌注后早期应用，以评估功能失调心肌的恢复潜力。此外，通过在1.5特斯拉使用TE 60多层自旋回波成像序列，也可能对梗死范围进行量化。
