Assessment of LV volume & function by real time 3-dimensional echocardiography

左室容积是心脏病患者预后的重要指标。虽然有几种方法可以评估左室容积，但大多数方法都有重要的内在局限性。实时三维超声心动图（RT3D回声）是一种能够即时获取体积图像的新技术。本研究旨在验证RT3D超声快速计算左室容积的有效性，并确定其在心脏病患者中的实用性。最初，我们报告了25例患者的结果。在这些研究过程中，很明显，许多患者的心内膜边界定义不理想，无法进行可靠的容积计算。因此，我们决定修改方案，包括注射EchoGen，一种静脉注射造影剂，使左心室腔不透明，从而提高心内膜边界分辨率。我们研究了90例注射造影剂的患者，产生了75例可评估的患者。RT3D回声测量左室容积为25 ~ 408 ml（平均106+/-64 ml）， MRI测量左室容积为17 ~ 532ml（平均103+/-72）。RT3D与MRI测量有很强的相关性（r=0.92，平均差3+/-28 ml）。舒张末期和收缩期末期容积的测量在观察者间有很强的一致性（r=0.96，平均差值分别为-3+/-20和r=0.98，平均差值分别为1+/-12）。对比增强的RT3D回声与左室体积的MRI测量之间也有很强的相关性（r=0.95）。对比增强后，RT3D回波衍生测量值与mri衍生测量值之间的差异明显较小（3+/-28 ml基线与-2+/-23 ml对比，p=0.04）。当分析两种技术之间测量值的差异占MRI体积的百分比时，对比增强测量值有显着改善（基线时差异14%+/-38%，对比后差异4%+/-27%，p= 0.00005）。因此，在未选择的心脏病患者人群中，RT3D回声准确预测mri得出的左室容积。增强对比度可以改善心内膜边界的清晰度，减少左室体积计算的误差。

Left ventricular (LV) volumes are important prognostic indices in patients with heart disease. Although several methods can evaluate LV volumes, most have important intrinsic limitations. Real-time three-dimensional echocardiography (RT3D echo) is a novel technique capable of instantaneous acquisition of volumetric images. This study was undertaken to validate rapid LV volume calculations with RT3D echo and to determine their usefulness in cardiac patients. Initially, we reported the results obtained in 25 patients. During the course of these studies, it was apparent that an important number of patients had suboptimal endocardial border definition to allow for reliable volume calculation. We therefore decided to modify the protocol to include the injection of EchoGen, a contrast agent for intravenous injection that opacifies the left ventricular cavity and thus enhances endocardial border resolution. We have studied 90 patients with contrast injection that have yielded 75 evaluable patients. LV volume measurements ranged from 25 to 408 ml (mean 106+/-64 ml) by RT3D echo and from 17 to 532ml (mean 103+/-72) by MRI. There was a strong correlation between the RT3D and MRI measurements (r=0.92, mean difference 3+/-28 ml). There was strong inter-observer agreement for the measurement of end-diastolic and end-systolic volumes (r=0.96, mean difference -3+/-20 and r=0.98, mean difference 1+/-12, respectively). There was also a strong correlation between the contrast-enhanced RT3D echo and MRI measurements of LV volumes (r=0.95). The difference between RT3D echo-derived measurements and MRI-derived measurements was significantly smaller after contrast enhancement (3+/-28 ml baseline to -2+/-23 ml contrast, p=0.04). When the difference in measurements between the two techniques was analyzed as a percentage of the MRI volume, there was a significant improvement in the contrast-enhanced measurements (%difference 14%+/-38% at baseline, 4%+/-27% with contrast, p=.00005). Thus, in an unselected population of cardiac patients, RT3D echo accurately predicts MRI-derive LV volumes. Contrast enhacement improves endocardial border definition and reduces the error in LV volume calculations.