Laird E E, Williams E D
Phys Med Biol. 1987 Aug;32(8):985-99. doi: 10.1088/0031-9155/32/8/003.
Rotating gamma-camera tomography is the method of choice for 201Tl perfusion imaging to detect myocardial ischaemia or infarction, but the optimum technique has not previously been investigated. Variables which can affect the utility of the images include acquisition time, collimator sensitivity and resolution, spatial filtering, reconstruction matrix and display parameters. An 'Iowa' design myocardial phantom containing 201Tl, with a defect representing an unperfused area, was used to study the effect of these variables. Results were assessed by measuring image contrast and non-uniformity and by observer grading trials. Receiver operator characteristic (ROC) curves and contrast ratios indicated that filtering the acquisition data with a count-dependent (Metz) filter before reconstruction and using a narrow slice width gave best results. No single collimator was superior for all four defect locations investigated but low-energy general purpose and high-resolution collimators were preferred to those with greater sensitivity. Reducing acquisition time by a factor of four compared with that for routine patient imaging affected contrast ratio, uniformity and area under ROC curves insignificantly, provided the optimum reconstruction was used. Displaying tomographic sections in colour gave no improvement in ROC curves over monochrome images. Data acquisition time or administered 201Tl radioactivity might therefore be reduced below the 25 min and 80 MBq often used for patient studies.
旋转γ相机断层扫描是用于铊-201灌注成像以检测心肌缺血或梗死的首选方法，但此前尚未对最佳技术进行过研究。可能影响图像效用的变量包括采集时间、准直器灵敏度和分辨率、空间滤波、重建矩阵以及显示参数。使用一个含有铊-201的“爱荷华”设计心肌模型，其中有一个代表未灌注区域的缺损，以研究这些变量的影响。通过测量图像对比度和不均匀性以及进行观察者分级试验来评估结果。接收者操作特征（ROC）曲线和对比度比值表明，在重建前用计数依赖型（梅茨）滤波器对采集数据进行滤波并使用窄切片宽度可得到最佳结果。在所研究的所有四个缺损位置中，没有一种准直器是最优的，但低能通用型和高分辨率准直器比那些灵敏度更高的准直器更受青睐。与常规患者成像相比，将采集时间缩短四倍，只要使用最佳重建方法，对对比度比值、均匀性和ROC曲线下面积的影响并不显著。与单色图像相比，以彩色显示断层切片对ROC曲线并无改善。因此，数据采集时间或所给予的铊-201放射性活度可能可以降低到通常用于患者研究的25分钟和80兆贝可勒尔以下。
