Honda N, Machida K, Tsukada J, Kaizu H, Hosoba M
Department of Radiology, Saitama Medical Center, Saitama Medical School, Japan.
Eur J Nucl Med. 1987;13(8):404-7. doi: 10.1007/BF00292492.
The optimal frequency characteristic of Butterworth-Wiener filters (BWF) for improving the image quality of 201Tl myocardial SPECT was determined by a phantom experiment. Thirty two projection images of the phantom containing 11.1 MBq of 201Tl with 4 different cold lesions were collected during a 180 degree arc of a gamma camera. A set of the projection images were processed with each of 27 different BWFs, and SPECT images were reconstructed by Shepp-Logan filtered backprojection. The SPECT images were evaluated for their diagnostic ability to visibly detect the cold lesions by four nuclear medicine physicians. The lesion contrasts were used as an adjunctive tool to determine the optimum filter. The optimal combination of the parameters determining BWF characteristics (for the data of about 100 count/pixel at the myocardium) is: 1) cutoff of 0.25/pixel, 2) FWHM of 3 pixels, 3) noise/signal ratio of 0.02. FWHM and noise/signal ratio affected lesion contrast much less than cutoff frequency. Clinical myocardial SPECT images processed with the optimal BWF showed less noise and sharper delineation of the myocardium.
通过体模实验确定了巴特沃斯 - 维纳滤波器（BWF）用于改善201Tl心肌单光子发射计算机断层扫描（SPECT）图像质量的最佳频率特性。在γ相机180度的圆弧范围内，采集了含有11.1MBq的201Tl且带有4种不同冷区病变的体模的32幅投影图像。用27种不同的BWF分别处理一组投影图像，并通过Shepp-Logan滤波反投影重建SPECT图像。由四位核医学医师对SPECT图像检测冷区病变的可视诊断能力进行评估。病变对比度用作确定最佳滤波器的辅助工具。确定BWF特性的参数的最佳组合（对于心肌处约100计数/像素的数据）为：1）截止频率为0.25/像素，2）半高宽为3像素，3）噪声/信号比为0.02。半高宽和噪声/信号比对病变对比度的影响远小于截止频率。用最佳BWF处理的临床心肌SPECT图像显示出噪声更少且心肌轮廓更清晰。
