Elangovan Premkumar, Mackenzie Alistair, Dance David R, Young Kenneth C, Cooke Victoria, Wilkinson Louise, Given-Wilson Rosalind M, Wallis Matthew G, Wells Kevin
Medical Imaging Group, Centre for Vision, Speech, and Signal Processing, University of Surrey, Guildford, GU2 7XH, United Kingdom. National Coordination Centre for the Physics of Mammography (NCCPM), Royal Surrey County Hospital, Guildford, GU2 7XX, United Kingdom.
Phys Med Biol. 2017 Apr 7;62(7):2778-2794. doi: 10.1088/1361-6560/aa622c.
A novel method has been developed for generating quasi-realistic voxel phantoms which simulate the compressed breast in mammography and digital breast tomosynthesis (DBT). The models are suitable for use in virtual clinical trials requiring realistic anatomy which use the multiple alternative forced choice (AFC) paradigm and patches from the complete breast image. The breast models are produced by extracting features of breast tissue components from DBT clinical images including skin, adipose and fibro-glandular tissue, blood vessels and Cooper's ligaments. A range of different breast models can then be generated by combining these components. Visual realism was validated using a receiver operating characteristic (ROC) study of patches from simulated images calculated using the breast models and from real patient images. Quantitative analysis was undertaken using fractal dimension and power spectrum analysis. The average areas under the ROC curves for 2D and DBT images were 0.51 ± 0.06 and 0.54 ± 0.09 demonstrating that simulated and real images were statistically indistinguishable by expert breast readers (7 observers); errors represented as one standard error of the mean. The average fractal dimensions (2D, DBT) for real and simulated images were (2.72 ± 0.01, 2.75 ± 0.01) and (2.77 ± 0.03, 2.82 ± 0.04) respectively; errors represented as one standard error of the mean. Excellent agreement was found between power spectrum curves of real and simulated images, with average β values (2D, DBT) of (3.10 ± 0.17, 3.21 ± 0.11) and (3.01 ± 0.32, 3.19 ± 0.07) respectively; errors represented as one standard error of the mean. These results demonstrate that radiological images of these breast models realistically represent the complexity of real breast structures and can be used to simulate patches from mammograms and DBT images that are indistinguishable from patches from the corresponding real breast images. The method can generate about 500 radiological patches (~30 mm × 30 mm) per day for AFC experiments on a single workstation. This is the first study to quantitatively validate the realism of simulated radiological breast images using direct blinded comparison with real data via the ROC paradigm with expert breast readers.
已开发出一种新方法来生成准逼真的体素模型，该模型可模拟乳腺钼靶摄影和数字乳腺断层合成（DBT）中的压缩乳房。这些模型适用于需要逼真解剖结构的虚拟临床试验，这些试验使用多重交替强迫选择（AFC）范式以及完整乳房图像中的补丁。乳房模型是通过从DBT临床图像中提取乳腺组织成分的特征而生成的，这些成分包括皮肤、脂肪和纤维腺组织、血管和库珀韧带。然后，通过组合这些成分可以生成一系列不同的乳房模型。使用接收器操作特征（ROC）研究对视觉逼真度进行了验证，该研究针对使用乳房模型计算出的模拟图像和真实患者图像中的补丁。使用分形维和功率谱分析进行了定量分析。二维和DBT图像的ROC曲线下平均面积分别为0.51±0.06和0.54±0.09，这表明专家乳腺阅片者（7名观察者）在统计学上无法区分模拟图像和真实图像；误差表示为均值的一个标准误差。真实图像和模拟图像的平均分形维数（二维，DBT）分别为（2.72±0.01，2.75±0.01）和（2.77±0.03，2.82±0.04）；误差表示为均值的一个标准误差。在真实图像和模拟图像的功率谱曲线之间发现了极好的一致性，平均β值（二维，DBT）分别为（3.10±0.17，3.21±0.11）和（3.01±0.32，3.19±0.07）；误差表示为均值的一个标准误差。这些结果表明，这些乳房模型的放射图像真实地反映了真实乳房结构的复杂性，可用于模拟乳腺钼靶摄影和DBT图像中的补丁，这些补丁与相应真实乳房图像中的补丁无法区分。该方法每天可在单个工作站上为AFC实验生成约500个放射学补丁（约30毫米×30毫米）。这是第一项通过与专家乳腺阅片者采用ROC范式与真实数据进行直接盲法比较来定量验证模拟放射学乳房图像逼真度的研究。
