Serial echocardiographic assessments are common in clinical cardiology, e.g., for timing of intervention in mitral and aortic regurgitation. When following patients with serial echocardiograms, each new measurement is a combination of true change and confounding noise. The current investigation compares linear chamber dimensions with volume estimates of chamber size. The aim is to assess which measure is best for serial echocardiograms, when the ideal parameter will be sensitive to change in chamber size and have minimal spurious variation (noise). We present a method that disentangles true change from noise. Linear regression of chamber size against elapsed time gives a slope, being the ability of the method to detect change. Noise is the scatter of individual points away from the trendline, measured as the standard error of the slope. The higher the signal-to-noise ratio (SNR), the more reliably a parameter will distinguish true change from noise. LV and LA parasternal dimensions and apical biplane volumes were obtained from serial clinical echocardiogram reports. Change over time was assessed as the slope of the linear regression line, and noise was assessed as the standard error of the regression slope. Signal-to-noise ratio is the slope divided by its standard error. The median number of LV studies was 5 (4–11) for LV over a mean duration of 5.9 ± 3.0 years in 561 patients (diastole) and 386 (systole). The median number of LA studies was 5 (4–11) over a mean duration of 5.3 ± 2.0 years in 137 patients. Linear estimates of LV size had better signal-to-noise than volume estimates (p < 0.001 for diastolic and p = 0.035 for systolic). For the left atrium, the difference was not significant (p = 0.214). This may be due to sample size; the effect size was similar to that for LV systolic size. All three parameters had a numerical value of signal-to-noise that favoured linear dimensions over volumes. Linear measures of LV size have better signal-to-noise than volume measures. There was no difference in signal-to-noise between linear and volume measures of LA size, although this may be a Type II error. The use of regression lines may be better than relying on single measurements. Linear dimensions may clarify whether changes in volumes are real or spurious.

中文翻译：

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左心室和左心房尺寸的线性和体积测量的信噪比

系列超声心动图评估在临床心脏病学中很常见，例如，用于确定二尖瓣和主动脉瓣反流的干预时机。当使用连续超声心动图跟踪患者时，每次新的测量都是真实变化和混杂噪声的组合。目前的研究将线性室尺寸与室尺寸的体积估计进行比较。目的是评估哪种测量最适合连续超声心动图，此时理想参数对腔室尺寸的变化敏感并且具有最小的杂散变化（噪声）。我们提出了一种将真实变化与噪音分开的方法。室尺寸与经过时间的线性回归给出斜率，即该方法检测变化的能力。噪声是各个点远离趋势线的分散度，以斜率的标准误差来测量。信噪比 (SNR) 越高，参数区分真实变化和噪声的能力就越可靠。LV 和 LA 胸骨旁尺寸和心尖双平面体积从系列临床超声心动图报告中获得。随时间的变化被评估为线性回归线的斜率，噪声被评估为回归斜率的标准误差。信噪比是斜率除以标准误差。LV 研究的中位数为 5 项 (4-11)，平均持续时间为 5.9 ± 3.0 年，涉及 561 名患者（舒张期）和 386 名患者（收缩期）。LA 研究的中位数为 5 项（4-11 项），平均持续时间为 5.3 ± 2.0 年，涉及 137 名患者。左心室大小的线性估计比容量估计具有更好的信噪比（舒张压 p < 0.001，收缩压 p = 0.035）。对于左心房，差异不显着 (p = 0.214)。这可能是由于样本量的原因；效应大小与 LV 收缩压大小相似。所有三个参数都有一个信噪比数值，该数值有利于线性尺寸而不是体积。左心室大小的线性测量比体积测量具有更好的信噪比。LA 大小的线性测量和体积测量之间的信噪比没有差异，尽管这可能是 II 类错误。使用回归线可能比依赖单一测量更好。线性尺寸可以澄清体积变化是真实的还是虚假的。