O'Connor M K, Leong L K, Gibbons R J
Department of Radiology, Mayo Clinic, Rochester, Minnesota 55905, USA.
J Nucl Med. 2000 Aug;41(8):1383-90.
The aim of this study was to determine the reproducibility of measurements of the size and severity of myocardial defects from 99mTc sestamibi cardiac phantom studies performed on multiple different gamma camera systems.
A total of 250 gamma camera systems were evaluated over a 5-y period as part of the validation process of multiple multicenter trials. Each laboratory performed 9 acquisitions of a cardiac phantom. Small myocardial defects (0%-30% of myocardial mass) were placed in the inferobasal region, whereas larger defects (40%-70%) were located in the anterior wall. Five representative short-axis slices were analyzed to determine defect size and severity (i.e., contrast in defect region) using circumferential short-axis count profiles. Defect size and severity were analyzed as a function of the type of collimator, gamma camera system, and type of orbit (180degrees versus 360degrees).
Of the 250 systems, image data were acquired correctly and showed an acceptable correlation between true and measured defect size in 198 systems. For these systems, the slope of the regression line between true and measured defect size was 1.03 +/- 0.03, with an average absolute error in estimating defect size of 1.7% +/- 0.5% and a correlation coefficient r = 0.99 +/- 0.01. Results were independent of the gamma camera system, type of collimator, and orbit. Contrast in the defect region (minimum count/maximum count) showed a small dependence on collimator resolution and pixel size but was altered significantly by the type of acquisition orbit, with a 360 degrees orbit showing better contrast for defects located in the inferobasal wall than a 180degrees orbit.
Measurement of defect size is independent of the gamma camera system, type of collimator, and orbit. Contrast in small defects located in the inferobasal wall of the heart is affected significantly by the type of acquisition orbit but not by the type of collimator.
本研究的目的是确定在多个不同的γ相机系统上进行的99mTc司他米比心肌模型研究中，心肌缺损大小和严重程度测量的可重复性。
在5年的时间里，共评估了250个γ相机系统，作为多个多中心试验验证过程的一部分。每个实验室对心脏模型进行9次采集。小的心肌缺损（心肌质量的0%-30%）置于下基底区域，而较大的缺损（40%-70%）位于前壁。分析五个代表性的短轴切片，使用圆周短轴计数轮廓来确定缺损大小和严重程度（即缺损区域的对比度）。缺损大小和严重程度作为准直器类型、γ相机系统和轨道类型（180度与360度）的函数进行分析。
在250个系统中，有198个系统正确采集了图像数据，并且真实缺损大小与测量缺损大小之间显示出可接受的相关性。对于这些系统，真实缺损大小与测量缺损大小之间回归线的斜率为1.03±0.03，估计缺损大小的平均绝对误差为1.7%±0.5%，相关系数r = 0.99±0.01。结果与γ相机系统、准直器类型和轨道无关。缺损区域的对比度（最小计数/最大计数）对准直器分辨率和像素大小有较小的依赖性，但受采集轨道类型的显著影响，360度轨道对位于下基底壁的缺损显示出比180度轨道更好的对比度。
缺损大小的测量与γ相机系统、准直器类型和轨道无关。位于心脏下基底壁的小缺损的对比度受采集轨道类型的显著影响，但不受准直器类型的影响。
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