Daimon M, Beppu S, Ishikura F, Ueda H, Kobayashi H, Kashiwagi Y, Yagura S, Yoshikawa J
Department of Internal Medicine of Cardiology, Graduate School of Medicine, Osaka City University, Osaka.
J Cardiol. 2001 Apr;37(4):201-7.
Myocardial contrast echocardiography is useful to assess myocardil perfusion, but myocardial opacification is affected by the setup of the ultrasonic equipment. The optimal setting of focus points for adequate opacification of the myocardium was examined in myocardial contrast echocardiography.
Myocardial contrast echocardiography was performed in six dogs using triggered second harmonic technology following intravenous administration of Optison(FS-69). The short-axis view was recorded and baseline subtracted video intensity(peak intensity: PI) was calculated at three regions of the left ventricular wall, the anterior, septum, and posterior walls, to evaluate myocardial opacification. The focus point was set at near(2 cm), middle(4 cm) and far(6 cm)points. The myocardial opacification was evaluated at each focus setting. The effect of the acoustic power was also examined by changing the mechanical index to 1.6, 1.2 or 0.8.
Myocardial opacification was recognized at all focus points, and segments near the focus points had high PI. However, the PI of the posterior wall was lowest at near focus, whereas the PI of the anterior wall was lowest at far focus. The difference of PI between the anterior and posterior walls was significant (p < 0.05, p < 0.01, respectively) at either focus point. Adequate myocardial opacification of all segments was observed when the focus was set at the middle point. The PI of the whole left ventricle increased relative to mechanical index.
Setting up of focus points at the middle of the left ventricle provides more homogeneous myocardial opacification of the whole left ventricle in myocardial contrast echocardiography, and high acoustic power possibly improves myocardial opacification. Inadequate setting of focus points leads to inadequate estimation of myocardial perfusion by myocardial contrast echocardiography.
心肌对比超声心动图有助于评估心肌灌注，但心肌显影受超声设备设置的影响。本研究在心肌对比超声心动图中检测了使心肌充分显影的最佳焦点设置。
对6只犬静脉注射Optison（FS - 69）后，采用触发式二次谐波技术进行心肌对比超声心动图检查。记录短轴视图，并计算左心室壁三个区域（前壁、室间隔和后壁）的基线扣除视频强度（峰值强度：PI），以评估心肌显影情况。焦点设置在近场（2 cm）、中场（4 cm）和远场（6 cm）。在每个焦点设置下评估心肌显影情况。还通过将机械指数改为1.6、1.2或0.8来检测声功率的影响。
在所有焦点处均可见心肌显影，焦点附近的节段PI较高。然而，后壁在近场焦点处的PI最低，而前壁在远场焦点处的PI最低。在任一焦点处，前壁和后壁之间的PI差异均有统计学意义（分别为p < 0.05，p < 0.01）。当焦点设置在中场时，所有节段均观察到充分的心肌显影。整个左心室的PI随机械指数增加。
在心肌对比超声心动图中，将焦点设置在左心室中部可使整个左心室的心肌显影更均匀，高声功率可能改善心肌显影。焦点设置不当会导致心肌对比超声心动图对心肌灌注的估计不足。
