Everaert H, Franken P R, Flamen P, Goris M, Momen A, Bossuyt A
Division of Nuclear Medicine, Univesity Hospital, Free University of Brussels (AZ VUB), Brussels, Belgium.
Eur J Nucl Med. 1996 Dec;23(12):1628-33. doi: 10.1007/BF01249626.
Left ventricular ejection fraction (LVEF) can be derived from gated single-photon emission tomographic (SPET) myocardial perfusion studies using either manual or edge detection techniques. In the presence of severe perfusion defects, however, difficulties may be encountered. In this article a method based on the assumption that the average position of the myocardial wall can be localized by means of statistical analysis of the distribution count density, and not on edge detection, is used to measure LVEF. SPET myocardial perfusion images, gated in eight time bins, were recorded in 50 patients 60 min after the injection of 925 MBq technetium-99m tetrofosmin. Masking of non-myocardial structures and thresholding resulted in images in which only myocardial walls had significant non-zero values. The distance of the wall relative to the centre of the cavity was calculated in the three-dimentional space as the first moment of the count rate distribution along radii originating in the centre of the cavity. LVEF was calculated using, for each time bin, the sum of the cube of all distances as an estimate of the cavity volume. The method required minimal operator interventions and was successful in all patients, including those with severe perfusion defects. Intraobserver and interobserver variability was excellent, with regression coefficients of 0.97 and standard deviations of 4.5% and 4.7%, respectively. For 30 patients, the measurements were validated against planar equilibrium radionuclide angiography (ERNA) that was obtained within an interval of 1 week. LVEF ranged from 12% to 88%. Agreement between the two methods was excellent (LVEFERNA=1.05+0.92 LVEFGSPET, r=0.93, P=0.023, SEE=7.06). The Bland-Altman analysis did not show any apparent trend in the differences between ERNA and gated SPET over a wide range of ejection fractions. The standard deviation of the differences was 3. 1%. In addition no relationship was found between the two methods and the severity of perfusion defects. In conclusion, accurate measurements of LVEF are obtained from gated SPET perfusion images using a method based on statistical analysis of the count rate density. This method did not deteriorate even in the presence of severe perfusion defects and could therefore be used in following patients after myocardial infarction.
左心室射血分数（LVEF）可通过门控单光子发射断层扫描（SPET）心肌灌注研究，使用手动或边缘检测技术得出。然而，在存在严重灌注缺损的情况下，可能会遇到困难。在本文中，一种基于以下假设的方法被用于测量LVEF：心肌壁的平均位置可通过对分布计数密度进行统计分析来定位，而非基于边缘检测。在注射925MBq锝-99m替曲膦60分钟后，对50例患者进行了门控在八个时间间隔的SPET心肌灌注图像记录。对非心肌结构进行屏蔽和阈值处理后，得到的图像中只有心肌壁具有显著的非零值。在三维空间中，将壁相对于腔中心的距离计算为沿源自腔中心的半径的计数率分布的一阶矩。对于每个时间间隔，使用所有距离的立方和作为腔体积的估计值来计算LVEF。该方法所需的操作员干预最少，并且在所有患者中均成功应用，包括那些有严重灌注缺损的患者。观察者内和观察者间的变异性都很好，回归系数分别为0.97，标准差分别为4.5%和4.7%。对30例患者，在1周内间隔获取的平面平衡放射性核素血管造影（ERNA）对测量结果进行了验证。LVEF范围为12%至88%。两种方法之间的一致性很好（LVEFERNA = 1.05 + 0.92 LVEFGSPET，r = 0.93，P = 0.023，SEE = 7.06）。Bland - Altman分析未显示在广泛的射血分数范围内ERNA和门控SPET之间的差异有任何明显趋势。差异的标准差为3.1%。此外，未发现两种方法与灌注缺损的严重程度之间存在关系。总之，使用基于计数率密度统计分析的方法，可从门控SPET灌注图像中准确测量LVEF。即使在存在严重灌注缺损的情况下，该方法也不会变差，因此可用于心肌梗死后的患者随访。
