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

左心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LV容量，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（RT 3D echo）是一种能够即时采集体积图像的新技术。本研究旨在验证使用RT 3D超声心动图快速计算LV容积，并确定其在心脏病患者中的有用性。 最初，我们报告了25例患者的结果。 在这些研究的过程中，很明显，大量患者的内镜边界定义不理想，无法进行可靠的体积计算。 因此，我们决定修改方案，以包括EchoGen的注射，EchoGen是一种用于静脉注射的造影剂，可使左心室腔不透明，从而提高内膜边界分辨率。 我们研究了90例注射造影剂的患者，共获得75例可评价患者。 通过RT 3D超声心动图测量的LV容积范围为25至408 ml（平均106+/-64 ml），通过MRI测量的LV容积范围为17至532 ml（平均103+/-72 ml）。 RT 3D和MRI测量值之间存在强相关性（r=0.92，平均差异3+/-28 ml）。舒张末期和收缩末期容积的测量结果在观察者之间具有很强的一致性（分别为r=0.96，平均差异-3+/-20和r=0.98，平均差异1+/-12）。 对比增强的RT 3D回波和左心室容积的MRI测量值之间也有很强的相关性（r=0.95）。对比增强后，RT 3D回波测量值与MRI测量值之间的差异显著更小（3+/-28 ml基线对比度至-2+/-23 ml对比度，p=0.04）。 当将两种技术之间的测量差异作为MRI体积的百分比进行分析时，对比增强测量结果有显著改善（基线时的差异%为14%+/-38%，造影剂为4%+/-27%，p= 0.00005）。 因此，在心脏病患者中，RT 3D回波可准确预测MRI导出的LV容积。对比度增强改善了左室内径边界的清晰度，并减少了左室容积计算的误差。

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.