Knesaurek K, Machac J
Division of Nuclear Medicine, Mount Sinai Medical Center, New York 10029, USA.
Med Phys. 1997 Dec;24(12):1914-23. doi: 10.1118/1.598105.
A newly developed cross-talk correction method for simultaneous dual-isotope SPECT imaging was tested in a canine model. The method is based on the assumption that the transformations, which modify the primary energy window images into the scatter images as viewed in the other energy windows, are known. These transformations were found by measuring the point spread functions (PSFs) in two different energy windows for both isotopes in water. The dual-isotope correction method is described by two convolution equations which were applied in frequency space. The equations take into account the different spatial distributions of the primary and scatter cross-talk photons. The new enhancement of the method was in applying restoration filters to the resulting corrected images. Three separate studies were acquired in our dog study: two single-isotope and one dual-isotope study. The single isotope images were used as references. The contrast between the left ventricle cavity (LVC) and the myocardium was used in transaxial and short-axis slices as a parameter to evaluate results of dual-isotope correction method with restoration. The change in contrast in the dual-isotope corrected images in both energy windows, i.e., Tc-99m primary window (140 keV) and Tl-201 primary window (70 keV), was significant. The only exception was for the short-axis Tc-99m window images. The corrected 140 keV dual-isotope short-axis slice had the contrast of 0.60 vs 0.58, which was the value in the noncorrected dual-isotope short-axis slice. For dual-isotope 140 keV transaxial slice, the contrast changed from 0.72 to 0.82 after correction. In comparison, for single-isotope Tc-99m 140 keV transaxial slice, contrast changed from 0.62 to 0.84 after restoration correction. There was less change in contrast in the short-axis Tc-99m 140 keV slice, i.e., from 0.56 to 0.61. In the Tl-201 primary window for the transaxial slices the improvement of contrast was from 0.38 to 0.64, and for short-axis slices from 0.22 to 0.32 after correction. In the same 70 keV energy window for single-isotope Tl-201 images, contrast improved from 0.61 to 0.69 and from 0.35 to 0.38 for transaxial and short-axis slice, respectively, after applying restoration correction. In conclusion, the presented dual-isotope correction method with restoration improves the quality of the simultaneous rest Tl-201/stress Tc-99m sestamibi SPECT imaging.
一种新开发的用于同时双同位素SPECT成像的串扰校正方法在犬模型中进行了测试。该方法基于这样的假设，即那些将主要能量窗图像转换为在其他能量窗中所观察到的散射图像的变换是已知的。通过测量水中两种同位素在两个不同能量窗中的点扩散函数（PSF）来找到这些变换。双同位素校正方法由在频率空间中应用的两个卷积方程描述。这些方程考虑了主要和散射串扰光子的不同空间分布。该方法的新改进在于对所得校正图像应用恢复滤波器。在我们的犬类研究中进行了三项单独的研究：两项单同位素研究和一项双同位素研究。单同位素图像用作参考。左心室腔（LVC）与心肌之间的对比度在横轴和短轴切片中用作评估具有恢复功能的双同位素校正方法结果的参数。在两个能量窗中，即Tc - 99m主要窗（140 keV）和Tl - 201主要窗（70 keV），双同位素校正图像中的对比度变化是显著的。唯一的例外是短轴Tc - 99m窗图像。校正后的140 keV双同位素短轴切片的对比度为0.60，而未校正的双同位素短轴切片的值为0.58。对于双同位素140 keV横轴切片，校正后对比度从0.72变为0.82。相比之下，对于单同位素Tc - 99m 140 keV横轴切片，恢复校正后对比度从0.62变为0.84。在短轴Tc - 99m 140 keV切片中对比度变化较小，即从0.56变为0.61。在横轴切片的Tl - 201主要窗中，校正后对比度从0.38提高到0.64，对于短轴切片从0.22提高到0.32。在相同的70 keV能量窗中，对于单同位素Tl - 201图像，应用恢复校正后，横轴切片对比度从0.61提高到0.69，短轴切片从0.35提高到0.38。总之，所提出的具有恢复功能的双同位素校正方法提高了同时静息Tl - 201/负荷Tc - 99m sestamibi SPECT成像的质量。
