Lauerma K, Saeed M, Wendland M F, Derugin N, Yu K K, Higgins C B
Department of Radiology, University of California, San Francisco.
Invest Radiol. 1994 May;29(5):527-35. doi: 10.1097/00004424-199405000-00001.
Magnetic resonance imaging (MRI) was used to demonstrate the infarction size in reperfused ischemic myocardium of normal and hypertrophied hearts, and to test the hypothesis that hypertrophied hearts manifest greater susceptibility to ischemia.
Normal rats (n = 11) and rats subjected to left ventricular hypertrophy (LVH) by aortic banding (n = 13) were studied. After 7 weeks, the left coronary artery was occluded for 25 minutes and reperfused for 1 hour before MRI. Electrocardiogram-gated spin-echo images were acquired before and after administration of 0.3 mmol/kg gadoteridol. To quantify the hyperintense area demarcated by gadoteridol, 3 transaxial images were acquired at different levels. Jeopardy and infarcted areas were measured in the same three slices postmortem using blue dye and triphenyltetrazolium chloride (TTC) stain, respectively.
Before administration, there was no significant difference in signal intensity between nonischemic (0.42 +/- 0.03 arbitrary units) and ischemic (0.41 +/- 0.03) myocardium in either group. After gadoteridol injection, signal intensity of the reperfused injured region was higher than that of nonischemic myocardium (1.48 +/- 0.16 vs. 0.72 +/- 0.06, P < .05). Magnetic resonance delineation of the hyperintense area persisted for at least 30 minutes. The size of the hyperintense area was larger in LVH than in control hearts (25 +/- 5% vs. 7 +/- 3% of LV surface area, P < .05) and did relate closely to the area of myocardial infarction (r = .97), but not with the jeopardy area (r = .42). On TTC staining, the infarction size also was significantly greater in LVH than in normal group (18 +/- 5% vs. 5 +/- 2% of LV surface area, P < .05). The jeopardy areas of normal and LVH hearts showed no significant difference (46 +/- 2% vs. 47 +/- 3%).
Magnetic resonance imaging confirms the concept that reperfused myocardial injury is larger in LVH than normal hearts after brief coronary occlusion. Contrast-enhanced MRI can define the size of reperfused myocardial injury. Thus, MRI is a suitable technique to assess conditions accentuating ischemic injury.
采用磁共振成像（MRI）显示正常心脏和肥厚心脏再灌注缺血心肌的梗死面积，并验证肥厚心脏对缺血更敏感这一假说。
研究正常大鼠（n = 11）和通过主动脉缩窄造成左心室肥厚（LVH）的大鼠（n = 13）。7周后，在进行MRI检查前，将左冠状动脉闭塞25分钟，然后再灌注1小时。在静脉注射0.3 mmol/kg钆喷酸葡胺前后采集心电图门控自旋回波图像。为量化钆喷酸葡胺勾勒出的高强度区域，在不同层面采集3张横轴位图像。在尸检时，分别使用蓝色染料和氯化三苯基四氮唑（TTC）染色测量同3个切片中的危险区和梗死区。
给药前，两组的非缺血心肌（0.42±0.03任意单位）和缺血心肌（0.41±0.03）信号强度无显著差异。注射钆喷酸葡胺后，再灌注损伤区域的信号强度高于非缺血心肌（1.48±0.16对0.72±0.06，P <.05）。高强度区域的磁共振描绘持续至少30分钟。LVH组高强度区域的面积大于对照组心脏（占左心室表面积的25±5%对7±3%，P <.05），且与心肌梗死面积密切相关（r =.97），但与危险区无关（r =.42）。TTC染色显示，LVH组的梗死面积也显著大于正常组（占左心室表面积的18±5%对5±2%，P <.05）。正常心脏和LVH心脏的危险区无显著差异（46±2%对47±3%）。
磁共振成像证实了短暂冠状动脉闭塞后，LVH心脏再灌注心肌损伤大于正常心脏这一概念。对比增强MRI可确定再灌注心肌损伤的面积。因此，MRI是评估加重缺血性损伤情况的合适技术。
