Optimization of regularization of attenuation and scatter-corrected 99mTc cardiac SPECT studies for defect detection using hybrid images
Optimization of regularization of attenuation and scatter-corrected 99mTc cardiac SPECT studies for defect detection using hybrid images
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DOI：
10.1109/23.940164
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发表时间：
2001-06-01
影响因子：
1.8
通讯作者：
Gifford, HC
中科院分区：
文献类型：
--
作者：
Narayanan, MV;King, MA;Gifford, HC
通过接收器操作特性研究，我们优化了对衰减和散射进行校正的心肌发射有序子集期望最大化(OSEM)重建的迭代次数和三维(3-D)高斯后滤波。混合图像被用于这种优化，其中人工灌注缺陷被添加到临床患者研究中，这些研究被读取为正常灌流。测试条件包括三种不同的OSEM迭代次数(1、5和10)，每个子集使用四个角度，然后在每个迭代级别进行三维高斯低通滤波。除了没有应用后滤波的情况外，使用0.6、0.75、1和1.25像素的标准差(A)来改变高斯低通滤波的级别。四名观察者分别读取15种被调查测试条件的80幅图像，提供关于是否存在灌注缺陷的置信度评级。结果表明，在所有迭代中，对于较大的平台或较宽的后置滤波器范围(sigma=0.6到1像素)，都能获得最佳的检测性能。正如预期的那样，在这个宽泛的最大值的两端都可以看到性能的逐渐下降，其中图像要么经过了非常严重的平滑处理，要么只进行了很少的后期滤波。最后，OSEM的一次迭代似乎是合适的选择，因为只要用0.6到i像素或在0.6到i像素的范围内对重建进行后滤波，随着迭代次数的增加，检测精度没有显著的改善。
Through means of a receiver-operating-characteristics study, we optimize the iteration number and three-dimensional (3-D) Gaussian postfiltering of Tc-99m cardiac emission ordered-subset expectation-maximization (OSEM) reconstructions that implement corrections for both attenuation and scatter. Hybrid images, wherein artificial perfusion defects were added to clinical patient studies that were read as being normally perfused, were used for this optimization. The test conditions included three different iteration numbers of OSEM (1, 5, and 10) using four angles per subset, followed by 3-D Gaussian low-pass filtering at each iteration level. The level of Gaussian low-pass filtering was varied using standard deviations (a) of 0.6, 0.75, 1, and 1.25 pixels, in addition to a case where no postfiltering was applied. Four observers read 80 images for each of the 15 test conditions being investigated, providing confidence ratings as to the presence or absence of perfusion defects. Results indicate that at all iterations, optimum detection performance is obtained for a broad plateau or range of postfilters (sigma = 0.6 to 1 pixel). As expected, a gradual reduction in performance is seen at either end of this broad maximum where the images either have been very heavily smoothed or have very little postfiltering. Finally, one iteration of OSEM appears to be the appropriate choice since no significant improvement in detection accuracy was observed with increasing iteration number as long as the reconstructions are postfiltered with or in the range of 0.6 to I pixel.