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A Deep Learning Approach to QSM Background Field Removal: Simulating Realistic Training Data Using a Reference Scan Ground Truth and Deformations
Oriana Vanesa Arsenov1, Karin Shmueli1, and Anita Karsa1
1Medical Physics and Biomedical Engineering, University College London, London, United Kingdom
We trained a deep-learning network for background field removal using random spatial deformations to simulate realistic fields (Model 1) and to augment field maps measured in vivo (Model 2). Model 1 predicts local fields better for synthetic vs in-vivo images. Model 2 performed better in vivo.
Figure 1. The architecture of the 3D U-net used for Background field removal (BGFR). The convolutional neural network (CNN) displays the output local field maps (Bint) the same size (192x192x96) as the input total field maps (Btot) . The number of feature maps is shown on top of each of the network’s layers.
Figure 2. A set of training field maps inside the brain simulated in a head and neck phantom with random deformations. A sagittal and a coronal slice of the total Btot (a), background Bext (b), and local Bint (c) field maps. The local fields are equal to the total fields minus the background fields: Bint = Btot - Bext.