Miao Jun, Huo Donglai, Wilson David L
Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio 44106, USA.
Med Phys. 2008 Jun;35(6):2541-53. doi: 10.1118/1.2903207.
The authors are using a perceptual difference model (Case-PDM) to quantitatively evaluate image quality of the thousands of test images which can be created when optimizing fast magnetic resonance (MR) imaging strategies and reconstruction techniques. In this validation study, they compared human evaluation of MR images from multiple organs and from multiple image reconstruction algorithms to Case-PDM and similar models. The authors found that Case-PDM compared very favorably to human observers in double-stimulus continuous-quality scale and functional measurement theory studies over a large range of image quality. The Case-PDM threshold for nonperceptible differences in a 2-alternative forced choice study varied with the type of image under study, but was approximately 1.1 for diffuse image effects, providing a rule of thumb. Ordering the image quality evaluation models, we found in overall Case-PDM approximately IDM (Sarnoff Corporation) approximately SSIM [Wang et al. IEEE Trans. Image Process. 13, 600-612 (2004)] > mean squared error NR [Wang et al. (2004) (unpublished)] > DCTune (NASA) > IQM (MITRE Corporation). The authors conclude that Case-PDM is very useful in MR image evaluation but that one should probably restrict studies to similar images and similar processing, normally not a limitation in image reconstruction studies.
作者们正在使用一种感知差异模型（Case-PDM）来定量评估在优化快速磁共振（MR）成像策略和重建技术时所生成的数千张测试图像的图像质量。在这项验证研究中，他们将来自多个器官以及多种图像重建算法的MR图像的人工评估结果与Case-PDM及类似模型进行了比较。作者们发现，在双刺激连续质量量表和功能测量理论研究中，在大范围的图像质量上，Case-PDM与人类观察者的比较结果非常有利。在二选一强制选择研究中，不可察觉差异的Case-PDM阈值随所研究图像的类型而变化，但对于弥散图像效果大约为1.1，提供了一个经验法则。对图像质量评估模型进行排序时，我们发现在总体上Case-PDM约等于IDM（萨诺夫公司）约等于SSIM[王等人，《IEEE图像处理汇刊》13卷，600 - 612页（2004年）]>均方误差NR[王等人（2004年）（未发表）]>DCTune（美国国家航空航天局）>IQM（米特里公司）。作者们得出结论，Case-PDM在MR图像评估中非常有用，但可能应该将研究限制在相似图像和相似处理上，这在图像重建研究中通常不是一个限制。
