Population-based studies of myocardial hypertrophy: high resolution cardiovascular magnetic resonance atlases improve statistical power
Population-based studies of myocardial hypertrophy: high resolution cardiovascular magnetic resonance atlases improve statistical power
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DOI：
10.1186/1532-429x-16-16
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发表时间：
2014-02-03
影响因子：
6.4
通讯作者：
O'Regan, Declan P.
中科院分区：
文献类型：
--
作者：
de Marvao, Antonio;Dawes, Timothy J. W.;O'Regan, Declan P.
背景：心脏表型，例如左心室（LV）质量，表现出高遗传力，尽管与这些复杂性状相关的大多数基因仍未确定。全基因组关联研究 (GWAS) 依赖传统的二维心血管磁共振 (CMR) 作为表型分析的黄金标准。然而，该技术对壁厚的区域变化不敏感，壁厚通常与左心室肥厚相关，并且需要大量的队列才能达到显着性。在这里，我们测试使用高空间分辨率 CMR 图集的自动心脏表型分析是否可以提高绘制健康人群壁厚的精度，以及与传统方法相比是否需要更小的样本量。方法：使用标准 2D 成像和 3D 高空间分辨率 CMR 在 138 名健康志愿者中获取左心室短轴电影图像。使用多图集技术来分割和共同配准每个图像。通过对 20 名受试者进行 Bland-Altman 分析，得出舒张末期容积和质量方法之间的一致性。通过一致体素的比例（Dice 系数）和分隔相应点的距离，将 LV 的 3D 和 2D 分割与手动标记进行比较。参数和非参数数据分别用配对 t 检验和 Wilcoxon 符号秩检验进行分析。体素功率计算使用壁厚的研究间方差。结果：3D 体积测量与 2D 成像相比没有偏差。分段 3D 图像比 2D 图像更准确地定义心外膜（Dice：0.95 vs 0.93，P < 0.001；平均误差 1.3 mm vs 2.2 mm，P < 0.001）和心内膜（Dice 0.95 vs 0.93，P < 0.001；平均误差 1.1 mm vs 2.0 mm，P < 0.001） 0.001）。与 2D 技术相比，3D 技术导致左室底部、隔膜和心尖处的壁厚评估存在显着差异 (P < 0.001)。 3D 成像检测 1 mm 壁厚差异所需的受试者数量较少（72 比 56，P < 0.001）。结论：具有自动表型分析功能的高空间分辨率 CMR 比传统 2D 成像提供了更大的壁厚绘制能力，并且能够减少研究左室壁厚的环境和遗传决定因素所需的样本量。
Background: Cardiac phenotypes, such as left ventricular (LV) mass, demonstrate high heritability although most genes associated with these complex traits remain unidentified. Genome-wide association studies (GWAS) have relied on conventional 2D cardiovascular magnetic resonance (CMR) as the gold-standard for phenotyping. However this technique is insensitive to the regional variations in wall thickness which are often associated with left ventricular hypertrophy and require large cohorts to reach significance. Here we test whether automated cardiac phenotyping using high spatial resolution CMR atlases can achieve improved precision for mapping wall thickness in healthy populations and whether smaller sample sizes are required compared to conventional methods.Methods: LV short-axis cine images were acquired in 138 healthy volunteers using standard 2D imaging and 3D high spatial resolution CMR. A multi-atlas technique was used to segment and co-register each image. The agreement between methods for end-diastolic volume and mass was made using Bland-Altman analysis in 20 subjects. The 3D and 2D segmentations of the LV were compared to manual labeling by the proportion of concordant voxels (Dice coefficient) and the distances separating corresponding points. Parametric and nonparametric data were analysed with paired t-tests and Wilcoxon signed-rank test respectively. Voxelwise power calculations used the interstudy variances of wall thickness.Results: The 3D volumetric measurements showed no bias compared to 2D imaging. The segmented 3D images were more accurate than 2D images for defining the epicardium (Dice: 0.95 vs 0.93, P < 0.001; mean error 1.3 mm vs 2.2 mm, P < 0.001) and endocardium (Dice 0.95 vs 0.93, P < 0.001; mean error 1.1 mm vs 2.0 mm, P < 0.001). The 3D technique resulted in significant differences in wall thickness assessment at the base, septum and apex of the LV compared to 2D (P < 0.001). Fewer subjects were required for 3D imaging to detect a 1 mm difference in wall thickness (72 vs 56, P < 0.001).Conclusions: High spatial resolution CMR with automated phenotyping provides greater power for mapping wall thickness than conventional 2D imaging and enables a reduction in the sample size required for studies of environmental and genetic determinants of LV wall thickness.