论文标题

与有条件生成的对抗网络合成逼真的胎儿MRI

Synthesis of realistic fetal MRI with conditional Generative Adversarial Networks

论文作者

Garcia, Marina Fernandez, Laiz, Rodrigo Gonzalez, Ji, Hui, Payette, Kelly, Jakab, Andras

论文摘要

胎儿脑磁共振成像是影响大脑疾病的产前咨询和诊断的新兴方式。基于机器学习的分割在大脑发育的量化中起着重要作用。但是,一个限制因素是缺乏足够大的标记培训数据。我们的研究探索了有条件的一般对抗网络(CGAN)Spade的应用,该应用程序从标签到图像空间学习了映射。网络的输入是120个胎儿的超分辨率T2加权大脑MRI数据(胎龄范围:20-35周,正常和病理),这是7种不同组织类别的注释。在每个正交方向上,对256*256 2D切片的重建体积(图像和标签对)进行了训练。为了将每个方向的生成量结合到一个图像中,采用了三个网络输出的简单平均值。仅基于标签地图,我们合成了高度逼真的图像。但是,某些细节(例如小容器)没有合成。结构相似性指数(SSIM)为0.972+-0.016,相关系数为0.974+-0.008。为了证明CGAN创建新的解剖变体的能力,我们人为地扩张了分割图中的心室,并创建了不同程度的胎儿脑积水的合成MRI。诸如Spade算法之类的CGANS允许在标签空间中产生假设的场景和解剖结构,又可以将数据用于训练各种机器学习算法。将来,该算法将用于生成代表胎儿脑发育的大型合成数据集。这些数据集可能会改善当前可用的细分网络的性能。

Fetal brain magnetic resonance imaging serves as an emerging modality for prenatal counseling and diagnosis in disorders affecting the brain. Machine learning based segmentation plays an important role in the quantification of brain development. However, a limiting factor is the lack of sufficiently large, labeled training data. Our study explored the application of SPADE, a conditional general adversarial network (cGAN), which learns the mapping from the label to the image space. The input to the network was super-resolution T2-weighted cerebral MRI data of 120 fetuses (gestational age range: 20-35 weeks, normal and pathological), which were annotated for 7 different tissue categories. SPADE networks were trained on 256*256 2D slices of the reconstructed volumes (image and label pairs) in each orthogonal orientation. To combine the generated volumes from each orientation into one image, a simple mean of the outputs of the three networks was taken. Based on the label maps only, we synthesized highly realistic images. However, some finer details, like small vessels were not synthesized. A structural similarity index (SSIM) of 0.972+-0.016 and correlation coefficient of 0.974+-0.008 were achieved. To demonstrate the capacity of the cGAN to create new anatomical variants, we artificially dilated the ventricles in the segmentation map and created synthetic MRI of different degrees of fetal hydrocephalus. cGANs, such as the SPADE algorithm, allow the generation of hypothetically unseen scenarios and anatomical configurations in the label space, which data in turn can be utilized for training various machine learning algorithms. In the future, this algorithm would be used for generating large, synthetic datasets representing fetal brain development. These datasets would potentially improve the performance of currently available segmentation networks.

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