The Medical Segment Anything Model (MedSAM) has demonstrated strong performance in medical image segmentation, attracting increasing attention in the medical imaging domain. However, as with many prompt-based segmentation models, its performance is highly sensitive to the type and location of input prompts. This sensitivity often leads to suboptimal segmentation outcomes and necessitates labor-intensive manual prompt tuning, which hampers both efficiency and robustness. To address this challenge, this paper proposes MedSAM-U, an uncertainty-guided framework designed to automatically refine prompt inputs and enhance segmentation reliability. Specifically, a Multi-Prompt Adapter is integrated into MedSAM, resulting in MPA-MedSAM, which enables the model to effectively accommodate diverse multi-prompt inputs. An uncertainty estimation module is then introduced to evaluate the reliability of the prompts and their initial segmentation results. Based on this, a novel uncertainty-guided prompt adaptation strategy is applied to automatically generate refined prompts and more accurate segmentation outputs. The proposed MedSAM-U framework is evaluated across multiple medical imaging modalities. Experimental results on five diverse datasets demonstrate that MedSAM-U achieves consistent performance improvements ranging from 1.7% to 20.5% over the baseline MedSAM, confirming its effectiveness and practicality for robust and efficient medical image segmentation.

In recent years, score-based diffusion models have emerged as effective tools for estimating score functions from empirical data distributions, particularly in integrating implicit priors with inverse problems like CT reconstruction. However, score-based diffusion models are rarely explored in challenging tasks such as metal artifact reduction (MAR). In this paper, we introduce a Bi-Constraints Diffusion Model for Metal Artifact Reduction (BCDMAR), an innovative approach that enhances iterative reconstruction with a conditional diffusion model for MAR. This method employs a metal artifact degradation operator in place of the traditional metal-excluded projection operator in the data-fidelity term, thereby preserving structure details around metal regions. However, score-based diffusion models tend to be susceptible to grayscale shifts and unreliable structures, making it challenging to reach an optimal solution. To address this, we utilize a pre-corrected image as a prior constraint, guiding the generation of the score-based diffusion model. By iteratively applying the score-based diffusion model and the data-fidelity step in each sampling iteration, BCDMAR effectively maintains reliable tissue representation around metal regions and produces highly consistent structures in non-metal regions. Through extensive experiments focused on metal artifact reduction tasks, BCDMAR demonstrates superior performance over other state-of-the-art unsupervised and supervised methods, both quantitatively and qualitatively.

Inserting an object into a background scene has wide applications in image editing and mixed reality. However, existing methods still struggle to seamlessly adapt the object to the background while maintaining its individual characteristics. In this article, we propose to fine-tune a pre-trained diffusion-based insertion model such that it learns to establish a unique correspondence between a few weights and the target object, given as input few-shot images of an object. A novel individualized feature extraction (IFE) module is designed to extract the individual detail features from few-shot object images. Then, the individual features of the target object, together with the semantic features of the target object and the background context features extracted by the pre-trained image encoders are injected into the cross-attention modules of the latent diffusion model, enabling it to learn the correlation information of the target object and the background scene through the attention mechanism. The weights obtained by fine-tuning implicitly serve as an alternative representation of the target object, with which the object can be easily inserted into any background images. Extensive comparative experiments validate the superiority of the proposed method to the state-of-the-art insertion methods in maintaining the individual details of the inserted object and adapting it to background scenes, including allowing the interaction between the inserted object and the background scene, correctly handling their occlusion relationship, maintaining the consistency of their viewpoints and poses.

Diffusion models have demonstrated remarkable efficacy in generating high-quality samples. Existing diffusion-based image restoration algorithms exploit pre-trained diffusion models to leverage data priors, yet they still preserve elements inherited from the unconditional generation paradigm. These strategies initiate the denoising process with pure white noise and incorporate random noise at each generative step, leading to over-smoothed results. In this paper, we present a refined paradigm for diffusion-based image restoration. Specifically, we opt for a sample consistent with the measurement identity at each generative step, exploiting the sampling selection as an avenue for output stability and enhancement. The number of candidate samples used for selection is adaptively determined based on the signal-to-noise ratio of the timestep. Additionally, we start the restoration process with an initialization combined with the measurement signal, providing supplementary information to better align the generative process. Extensive experimental results and analyses validate that our proposed method significantly enhances image restoration performance while consuming negligible additional computational resources.

Computed tomography (CT) is widely used in clinical medicine, and low-dose CT (LDCT) has become popular to reduce potential patient harm during CT acquisition. However, LDCT aggravates the problem of noise and artifacts in CT images, increasing diagnosis difficulty. Through deep learning, denoising CT images by artificial neural network has aroused great interest for medical imaging and has been hugely successful. We propose a framework to achieve excellent LDCT noise reduction using independent operation search cells, inspired by neural architecture search, and introduce the Laplacian to further improve image quality. Employing patch-based training, the proposed method can effectively eliminate CT image noise while retaining the original structures and details, hence significantly improving diagnosis efficiency and promoting LDCT clinical applications.

Deep convolutional networks have obtained remarkable achievements on various visual tasks due to their strong ability to learn a variety of features. A well-trained deep convolutional network can be compressed to 20%–40% of its original size by removing filters that make little contribution, as many overlapping features are generated by redundant filters. Model compression can reduce the number of unnecessary filters but does not take advantage of redundant filters since the training phase is not affected. Modern networks with residual, dense connections and inception blocks are considered to be able to mitigate the overlap in convolutional filters, but do not necessarily overcome the issue. To do so, we propose a new training strategy, weight asynchronous update, which helps to significantly increase the diversity of filters and enhance the representation ability of the network. The proposed method can be widely applied to different convolutional networks without changing the network topology. Our experiments show that the stochastic subset of filters updated in different iterations can significantly reduce filter overlap in convolutional networks. Extensive experiments show that our method yields noteworthy improvements in neural network performance.