长轴方向应变和应变率成像影响因素分析

目的探讨室壁与入射超声之间的夹角及应变长度（SL）对长轴方向应变成像（SI）和应变率成像（SRI）的影响。方法SRI定量分析模式下，取样容积置于健康人和冠心病患者心尖四腔观后间隔中部，SL分别设置为2mm、12mm和20mm，测量收缩期和舒张早期峰值应变率（SRs和SRe），比较不同SL条件下所测SRs和SRe有无差异。SI模式下心尖长轴观定性观察健康人、冠心病和扩张性心肌病患者左室各节段的彩色分布；改变成像角度，定性观察室壁彩色变化。结果SL改变时SRs和SRe显著变化，SRI二维图像与曲线质量亦发生变化；由于角度的影响，健康人、冠心病和扩张性心肌病患者均有反相应变节段，改变成像角度，室壁彩色分布亦发生变化。结论SI和SRI受角度和应变长度影响，实际应用中应注意切面和取样部位的选择及仪器的设置。

Study on influencing factors of strain imaging and strain rate imaging in long-axis direction

Objective To study the influence of incidence angle of ultrasound and strain length(SL) on strain imaging(SI) and strain rate imaging(SRI) in long-axis direction. Methods In the quantitative analysis mode of SRI, sample volume was placed on the mid posterior interventricular septum in healthy subjects and patients with coronary artery disease(CAD) to measure the peak strain rate during systole(SR_s) and early diastole(SR_e). SR_s and SR_e were compared respectively among different SL selections those were 2 mm, 12 mm and 20 mm. Color bands on left ventricular walls of healthy subjects, patients with CAD and dilated cardiomyopathy(DCM) in apical view were observed in SI mode. And alteration of color bands was studied qualitatively when imaging angle changed. Results SR_s and SR_e changed significantly with different SL and quality of SRI two-dimensional images and curves did too. Segments with reverse strain were found in healthy subjects, patients with CAD and DCM. Distribution of color bands on left ventricular walls changed with different imaging angle. Conclusions Incidence angle of ultrasound and SL are the influencing factors of SI and SRI, which means that angle and SL must be considered with the application of SI and SRI at the clinical settings.