Image synthesis in contrast MRI based on super resolution reconstruction with multi-refinement cycle-consistent generative adversarial networks

In the field of medical image processing represented by magnetic resonance imaging (MRI), synthesizing the complementary target contrast of the target patient from the existing contrast has obvious medical significance for assisting doctors in making clinical diagnoses. To satisfy the image translation problem between different MRI contrasts (T1 and T2), a generative adversarial network is proposed that works in an end-to-end manner at image level. The low-frequency and high-frequency information of the image is preserved by using multi-stage optimization learning aided by adversarial loss, the loss of perceptual consistency and the loss of cyclic consistency, as it results in preserving the same contrast anatomical structure of the source domain supervisely when the perceptual pixel distribution of the target contrast is learned perfectly. To integrate different penalties (L1 and L2) organically, adaptive weights are set for the error sensitivity of the penalty function in the present total loss function, the aim being to achieve adaptive optimization of each stage of generating high-resolution images. In addition, a new net structure called multi-skip connection residual net is proposed to refine medical image details step by step with multi-stage optimization. Compared with the existing technology, the present method is more advanced. The contrast conversion of T1 and T2 in MRI is validated, which can help to shorten the imaging time, improve the imaging quality, and effectively assist doctors with diagnoses.