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

左心室(LV)容量是预测心脏病患者预后的重要指标。虽然有几种方法可以评估左心室容量，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(RT3D ECHO)是一种能够瞬时获取容积图像的新技术。这项研究是为了验证使用RT3D ECHO快速计算左心室容量，并确定其在心脏病患者中的有效性。最初，我们报告了在25名患者中获得的结果。在这些研究的过程中，很明显，许多患者的心内膜边界清晰度不是最理想的，以允许可靠的容量计算。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名可评估的患者。RT3D超声心动图测量的左心室容积范围为25~408ml，平均为10~6+/-m l，MRI测量范围为17~532m l，平均为10~3+/-72。RT3D与MRI测量值之间有很强的相关性(r=0.92，平均差值3+/-28ml)。观察者间对舒张末和收缩末期容量的测量有很强的一致性(r=0.96，平均差值-3+/-20和r=0.98，平均差值1+/-12)。增强后的RT3D超声心动图与MRI测量的左心室容积之间也有很强的相关性(r=0.95)。增强后RT3D回声测量结果与MRI测量结果之间的差异显著缩小(基线为3+/-28毫升，对比度为-2+/-23毫升，p=0.04)。当两种技术之间的测量差异以MRI体积的百分比来分析时，对比增强的测量有了显著的改善(基线的%差异14%+/-38%，对比的%+/-27%，p=0.00005)。因此，在未选定的心脏病患者群体中，RT3D ECHO可以准确预测MRI得出的LV体积。对比度增强改善了心内膜边界的清晰度，减少了计算左心室容量的误差。

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.