von Birgelen C, de Feyter P J, de Vrey E A, Li W, Bruining N, Nicosia A, Roelandt J R, Serruys P W
Thoraxcenter, University Hospital, Rotterdam-Dijkzigt, The Netherlands.
Coron Artery Dis. 1997 Jun;8(6):363-9. doi: 10.1097/00019501-199706000-00005.
Volumetric intravascular ultrasound (IVUS) assessment provides complementary information on atherosclerotic plaques. The volumes can be calculated by applying Simpson's rule to cross-sectional area data of multiple IVUS images, acquired with a fixed sample spacing, which is the distance (along the vessel's axis) between two images.
To evaluate the effect of different sample spacings on the results of volumetric IVUS measurements.
A stepwise electrocardiographically gated IVUS image-acquisition and automated three-dimensional analysis approach was applied to 26 patients. Twenty-eight coronary segments with mild-to-moderate coronary atherosclerosis were examined. Volumetric measurements of five images per mm (i.e. sample spacing 0.2 mm), representing a complete scanning of the coronary segment, were considered the optimal standard, against which volumetric measurements of three, one, and one-half images per mm (i.e. larger sample spacings) were compared.
The lumen, total vessel, and plaque volumes obtained with five images per mm were 183.3 +/- 2.8, 350.6 +/- 141.6, and 167.3 +/- 89.2 mm3. There was an excellent correlation (r = 0.99, P < 0.001) between these data and volumetric measurements with larger sample spacings. The volumetric measurements with larger sample spacings differed on average only by a little (< 0.7%) from the optimal standard measurements. However, a relatively small, but significant, increase in SD of these differences was associated with the wider sample spacings (< 3.6%, P < 0.05).
The width of the sample spacing has a relatively small but significant impact on the variability of volumetric intravascular ultrasound measurements. This should be considered when designing future volumetric studies. The electrocardiographically gated acquisition of five IVUS images per mm axial length during a stepwise transducer pull-back is an ideal approach, particularly when addressing with IVUS volumetric changes that are assumed small, such as those expected in studies of the progression and regression of atherosclerosis.
血管内超声（IVUS）容积评估可提供有关动脉粥样硬化斑块的补充信息。容积可通过将辛普森法则应用于多个IVUS图像的横截面积数据来计算，这些图像以固定的样本间距采集，样本间距即两张图像之间（沿血管轴）的距离。
评估不同样本间距对血管内超声容积测量结果的影响。
对26例患者采用逐步心电图门控IVUS图像采集和自动三维分析方法。检查28个轻度至中度冠状动脉粥样硬化的冠状动脉节段。每毫米五张图像（即样本间距0.2毫米）的容积测量代表冠状动脉节段的完整扫描，被视为最佳标准，并与每毫米三张、一张和半张图像（即更大样本间距）的容积测量进行比较。
每毫米五张图像获得的管腔、血管总体积和斑块体积分别为183.3±2.8、350.6±141.6和167.3±89.2立方毫米。这些数据与更大样本间距的容积测量之间存在极好的相关性（r = 0.99，P < 0.001）。更大样本间距的容积测量与最佳标准测量平均仅相差一点（<0.7%）。然而，这些差异的标准差相对较小但有显著增加，与更宽的样本间距相关（<3.6%，P < 0.05）。
样本间距宽度对血管内超声容积测量的变异性有相对较小但显著的影响。在设计未来的容积研究时应考虑这一点。在换能器逐步回撤过程中，每毫米轴向长度进行心电图门控采集五张IVUS图像是一种理想的方法，特别是在研究动脉粥样硬化进展和消退等预计变化较小的血管内超声容积变化时。
