Metadata-guided cross-modality 3D MRI synthesis aims to generate target-contrast volumes from source-modality data conditioned on clinically available metadata, which is important for enhancing clinical imaging flexibility. However, existing methods still suffer from two main limitations: 1) They neglect spatial dependencies within volumetric representations, yielding structurally ambiguous features that blur anatomical boundaries and hinder precise semantic integration. 2) They rely on conventional cross-attention between visual and textual features, limiting the precision of visual-semantic alignment, which reduces robustness across challenging conditions. To address these issues, we propose RTFSyn, a metadata-guided 3D MRI synthesis framework that achieves effective vision-language collaboration through a refine-then-fusion paradigm. The proposed RTFSyn benefits from several merits. First, we design an axis-aware visual refinement module that captures directional dependencies within volumetric features, enabling redundancy suppression and improved structural representation before fusion. Second, we propose a cross-modal adaptive fusion module that leverages pixel packing-recovery to realize efficient cross-attention for improved alignment, while text-conditioned dynamic convolution enables fine-grained semantic injection, together enhancing vision-language collaboration. Lastly, an implicit neural decoder reconstructs the target modality as a continuous function, enabling flexible high-fidelity synthesis. Under this synergistic paradigm, RTFSyn seamlessly unites robust spatial refinement with adaptive feature fusion to achieve highly precise cross-modal alignment. Extensive experiments across four multi-center datasets demonstrate that RTFSyn not only surpasses state-of-the-art methods quantitatively, but also exhibits robust performance under diverse imaging artifacts, zero-shot evaluations, and multi-dimensional clinical validations, all with favorable computational efficiency. The high fidelity, robustness, and efficiency of RTFSyn demonstrate its great potential for clinical applications.

Medical image synthesis is crucial in clinical workflows, enabling the generation of missing modalities from available imaging data. While recent diffusion-based models show promise in medical image synthesis, they face two key limitations: progressive distribution drift from coarse intermediate samples and structural granularity loss due to missing high-frequency constraints. To address these challenges, we propose Dual Diffusion Bridge (DualDB), a framework integrating implicit distribution alignment and explicit structural constraints within a unified diffusion bridge paradigm. First, implicit distribution alignment employs optimal transport-guided adversarial learning to minimize statistical discrepancies between intermediate and target distributions, mitigating global distribution drift. Second, explicit structural alignment applies gradient-driven constraints to preserve high-frequency anatomical features, preventing structural degradation during reverse diffusion. This complementary design ensures both global statistical consistency and local anatomical precision in the synthesized results. Extensive experiments on multi-contrast MRI and MRI-CT translation show that DualDB outperforms state-of-the-art methods in quantitative performance and visual fidelity, maintaining superior anatomical accuracy even under noisy conditions.

Multi-contrast MRI super-resolution (SR) aims to restore high-resolution target image from low-resolution one, where reference image from another contrast is used to promote this task. To better meet clinical needs, current studies mainly focus on developing arbitrary-scale MRI SR solutions rather than fixed-scale ones. However, existing arbitrary-scale SR methods still suffer from the following two issues: 1) They typically rely on fixed convolutions to learn multi-contrast features, struggling to handle the feature transformations under varying scales and input image pairs, thus limiting their representation ability. 2) They simply combine the multi-contrast features as prior information, failing to fully exploit the complementary information in the texture-rich reference images. To address these issues, we propose a Dynamic Implicit Network (DINet) for multi-contrast MRI arbitrary-scale SR. DINet offers several key advantages. First, the scale-adaptive dynamic convolution facilitates dynamic feature learning based on scale factors and input image pairs, significantly enhancing the representation ability of multi-contrast features. Second, the dual-branch implicit attention enables arbitrary-scale upsampling of MR images through implicit neural representation. Following this, we propose the modulation-then-fusion block to adaptively align and fuse multi-contrast features, effectively incorporating complementary details from reference images into the target images. By jointly combining the above-mentioned modules, our proposed DINet achieves superior MRI SR performance at arbitrary scales. Extensive experiments on three datasets demonstrate that DINet significantly outperforms state-of-the-art methods, highlighting its potential for clinical applications. The code is available athttps://github.com/weijinbao1998/DINet.

Medical image restoration (MedIR) aims to recover high-quality images from degraded inputs, yet faces unique challenges from physics-driven degradations and multi-modal task interference. While existing all-in-one methods handle natural image degradations well, they struggle with medical scenarios due to limited degradation perception and suboptimal multi-task optimization. In response, we introduce DaPT, a Degradation-aware Prompted Transformer, which integrates dynamic prompt learning and modular expert mining for unified MedIR. First, DaPT introduces spatially compact prompts with optimal transport regularization, amplifying inter-prompt differences to capture diverse degradation patterns. Second, a mixture of experts dynamically routes inputs to specialized modules via prompt guidance, resolving task conflicts while reducing computational overhead. The synergy of prompt learning and expert mining further enables robust restoration across multi-modal medical data, offering a practical solution for clinical imaging. Extensive experiments across multiple modalities (MRI, CT, PET) and diverse degradations, covering both in-distribution and out-of-distribution scenarios, demonstrate that DaPT consistently outperforms state-of-the-art methods and generalizes reliably to unseen settings, underscoring its robustness, effectiveness, and clinical practicality. The source code will be released at https://github.com/weijinbao1998/DaPT.

In recent years, deep convolutional neural networks (CNNs) have become dominant in MRI reconstruction from undersampled k-space. However, most existing CNNs methods reconstruct the undersampled images either in the spatial domain or in the frequency domain, and neglecting the correlation between these two domains. This hinders the further reconstruction performance improvement. To tackle this issue, in this work, we propose a new multi-domain recurrent network (MDR-Net) with multi-domain learning (MDL) blocks as its basic units to reconstruct the undersampled MR image progressively. Specifically, the MDL block interactively processes the local spatial features and the global frequency information to facilitate complementary learning, leading to fine-grained features generation. Furthermore, we introduce an effective frequency-based loss to narrow the frequency spectrum gap, compensating for over-smoothness caused by the widely used spatial reconstruction loss. Extensive experiments on public fastMRI datasets demonstrate that our MDR-Net consistently outperforms other competitive methods and is able to provide more details.