Acquiring pixel-level annotations for medical images is an extremely time-consuming and labor-intensive task, typically occupying the majority of the development cycle for medical image segmentation models. While existing semi-supervised methods have achieved promising results, they generally still require annotations for 10%-30% of the samples to effectively guide learning from unlabeled data, which remains a substantial burden for real-world applications. In this study, we propose YoloSeg, a novel framework for medical image segmentation under extreme label scarcity, where only a single labeled image is available. YoloSeg integrates Segment Anything Model 2 to propagate labels from the labeled image to unlabeled images, thereby expanding the labeled data pool. To address the inherent noise in pseudo-labels, we employ multi-view label propagation, decomposing pseudo-labels into consensus and divergence regions. We introduce a dual-component loss to handle these regions separately, facilitating more robust pseudo-label learning for segmentation models. Additionally, we propose a cross-patch data augmentation strategy to generate new samples with stronger semantic consistency, further enhancing the stability of training and improving model generalization. We validate our method on ten diverse medical image segmentation datasets, encompassing a wide range of segmentation targets including organs, vessels, and lesions. Experimental results show that YoloSeg achieves performance comparable to fully-supervised baselines, with an average Dice score difference of only 3.08% across all tasks, and significantly outperforms other state-of-the-art semi-supervised and one-shot methods. YoloSeg significantly improves the feasibility and cost-effectiveness of deep learning in scenarios with severely limited annotation budgets. This approach holds promise for enabling the rapid development and deployment of custom segmentation models across diverse medical centers, thereby supporting the broader adoption of intelligent medical technologies. Code is available at https://github.com/iMED-Lab/YoloSeg.

Quantitative analysis of retinal vascular morphology is vital for clinical decision-making and the investigation of systemic diseases. Central to this process is the accurate segmentation of retinal arteries and veins (A/V) from the background, a task challenged by substantial variations in vessel calibers and the presence of low-contrast or ambiguous structures in fundus images, especially in ultra-wide field imaging where peripheral distortions and large-scale anatomical variability are pronounced. These factors often lead to fragmented semantic representations and topological inconsistencies in automated segmentation outputs. To address these limitations, we propose Ultra, a multi-granularity topological reasoning network designed for precise A/V segmentation. Ultra adopts a cascaded two-stage architecture: PriorNet generates coarse, multi-scale vascular priors that provide structural guidance, while RefineNet performs topology-aware segmentation refinement. To further enforce topological coherence, we propose the neighboring pixel connectivity regularization (NICER) layer, which selectively integrates local connectivity information predicted by the proposed connectivity prediction union (CPU) module. This connectivity is employed as auxiliary supervision through a pixel-wise local connectivity loss, reinforcing structural reasoning and promoting anatomically consistent vascular topology inference. Extensive experiments on ultra-wide field fundus imaging (UWF) datasets demonstrate that Ultra achieves state-of-the-art performance in A/V segmentation and topological preservation. Moreover, Ultra generalizes well to conventional color fundus photography (CFP) datasets, underscoring its robustness and broad applicability. Code is publicly available at: https://github.com/iMED-Lab/Ultra.

Brain tumors are highly lethal and debilitating pathological changes that require timely diagnosis and treatment. Magnetic resonance imaging (MRI), a non-invasive diagnostic tool, provides complementary multi-modal information crucial for accurate tumor detection and delineation. However, existing methods struggle to effectively fuse multi-modal information from MRI sequences and often fail to perform modality-specific feature extraction, which hinders accurate tumor segmentation. Furthermore, the inherent challenges posed by the blurred boundaries and complex morphological characteristics of tumor structures present additional substantial obstacles to achieving precise segmentation. To address these issues, we propose FiHam, a fine-grained hierarchical progressive modal-aware network that introduces a novel multi-modal fusion strategy and an advanced feature extraction mechanism. Specifically, FiHam employs a progressive fusion strategy that extracts modality-specific features at lower levels and integrates multi-modal features at higher levels to effectively leverage complementary information from tumor images. Additionally, we design a gated cross-attention modal-fusion module that adaptively selects and integrates dual-modal features using cross-attention mechanisms to enhance modality fusion. To further refine segmentation accuracy, we incorporate a tiny U-Net into the encoder to capture boundary features and complex tumor morphology. Extensive experiments on three large-scale, multi-modal brain tumor datasets demonstrate that FiHam achieves state-of-the-art performance, delivering significant improvements in segmentation accuracy and generalizability across diverse MRI modalities.

The morphological changes of corneal structures captured by corneal confocal microscopy (CCM), such as corneal nerves, Langerhans cells, stromal cells, etc., are closely related to various ocular and systemic diseases. Current CCM segmentation methods primarily focus on single-task, which limits their broad applicability in clinical practice. The absence of a standardized benchmark further presents a significant challenge in evaluating new methods. To this end, this paper presents a novel incremental learning-based approach for multi-structure segmentation in CCM images and a new benchmark. Specifically, we first propose a data fingerprint distillation (FIND) module to encode task-relevant knowledge by extracting compact representations of structures from CCM images via structural importance mapping. Building on FIND, we propose a progressive task-guided adapter learning (ProTA) strategy, which refines the model's representation of structures through a series of "easy-to-hard" distillation stages. ProTA dynamically adjusts the scope of task-relevant knowledge extracted by FIND, thereby improving the model's ability to accurately discriminate between multiple structures while enhancing knowledge transfer efficiency. Extensive experiments demonstrate that the proposed method achieves the state-of-the-art performance in terms of all corneal structures segmentation. We also demonstrate our approach's plug-and-play capability across four other medical image modalities, suggesting its potential as a general incremental learning tool. Additionally, this work seeks to provide a benchmark tool comprising a comprehensive dataset and their fine manual annotation, as well as unified benchmarking evaluations for state-of-the-art methods. All the dataset, source code and evaluation tool are publicly available at https://github.com/iMED-Lab/CCM-Pro.

Domain shifts between samples acquired with different instruments are one of the major challenges in accurate segmentation of Optical Coherence Tomography (OCT) images. Given that OCT images may be acquired with different devices in different clinical centers, this study presents astyle and structure data augmentation (SSDA) method to improve the adaptability of segmentation models. Inspired by our initial analysis of OCT domain differences, we propose an innovative hypothesis that domain shifts are primarily due to differences in image style and anatomical structure, which further guides the design of our method. By designing a modality-specific NURBS curve for style enhancement and implementing global and local elastic deformation fields, SSDA addresses both stylistic and structural variations in OCT data. Global deformations simulate changes in retinal curvature, while local deformations model layer-specific changes observed in OCT images. We validate our hypothesis through a comprehensive evaluation conducted on five OCT data domains, each differing in device type and imaging conditions. We train models on each of these domains for single-domain generalisation experiments and evaluate performance on the remaining unseen domains. The results show that SSDA outperforms existing methods when segmenting OCT images from different sources with different requirements for retinal layer segmentation. Specifically, across five different source domain generalisation experiments, SSDA achieves approximately 1.6% higher Dice and 2.6% improved MIOU, underscoring its superior segmentation accuracy and robust generalisation across all evaluated unseen domains.

Optical Coherence Tomography (OCT) imaging is extensively utilized for non-invasive observation of pathological conditions, such as retinal fluid-associated diseases. Accurate fluid segmentation in OCT images is therefore critical for quantifying disease severity and aiding clinical decision-making. However, achieving precise segmentation remains challenging due to pathological variations in shape and size, uncertain boundaries, and low contrast of fluid. Most importantly, variability in OCT image styles across different vendors and centers significantly affects fluid segmentation, leading to poor generalization to unseen domains. To address this, we propose a novel method, RSAPower, to enhance the generalization ability of fluid perception networks via style augmentation for retinal fluid segmentation. Specifically, RSAPower comprises a plug-and-play random style transform augmentation (RSTAug) module and a novel fluid perception network (FLPNet) for end-to-end training. The RSTAug module generates new random-style data from the source domain, preserving realistic pathological and structural features. The FLPNet benefits from a novel hybrid structure attention (HSA) module to perceive fluid's spatial features and long-range dependence. Furthermore, FLPNet adapts to the diverse augmented data through a saliency-guided multi-scale attention (SGMA) block, boosting its segmentation performance. We validate RSAPower against various state-of-the-art methods using two publicly available datasets, Retouch and Kermany. Experimental results demonstrate the proposed method's superior generalization ability and effectiveness in fluid segmentation.

Cerebrovascular diseases (CVDs) remain a leading cause of global disability and mortality. Digital Subtraction Angiography (DSA) sequences, recognized as the gold standard for diagnosing CVDs, can clearly visualize the dynamic flow and reveal pathological conditions within the cerebrovasculature. Therefore, precise segmentation of cerebral arteries (CAs) and classification between their main trunks and branches are crucial for physicians to accurately quantify diseases. However, achieving accurate CA segmentation in DSA sequences remains a challenging task due to small vessels with low contrast, and ambiguity between vessels and residual skull structures. Moreover, the lack of publicly available datasets limits exploration in the field. In this paper, we introduce a DSA Sequence-based Cerebral Artery segmentation dataset (DSCA), the publicly accessible dataset designed specifically for pixel-level semantic segmentation of CAs. Additionally, we propose DSANet, a spatio-temporal network for CA segmentation in DSA sequences. Unlike existing DSA segmentation methods that focus only on a single frame, the proposed DSANet introduces a separate temporal encoding branch to capture dynamic vessel details across multiple frames. To enhance small vessel segmentation and improve vessel connectivity, we design a novel TemporalFormer module to capture global context and correlations among sequential frames. Furthermore, we develop a Spatio-Temporal Fusion (STF) module to effectively integrate spatial and temporal features from the encoder. Extensive experiments demonstrate that DSANet outperforms other state-of-the-art methods in CA segmentation, achieving a Dice of 0.9033.

Time-of-flight magnetic resonance angiography (TOF-MRA) is the least invasive and ionizing radiation-free approach for cerebrovascular imaging, but variations in imaging artifacts across different clinical centers and imaging vendors result in inter-site and inter-vendor heterogeneity, making its accurate and robust cerebrovascular segmentation challenging. Moreover, the limited availability and quality of annotated data pose further challenges for segmentation methods to generalize well to unseen datasets. In this paper, we construct the largest and most diverse TOF-MRA dataset (COSTA) from 8 individual imaging centers, with all the volumes manually annotated. Then we propose a novel network for cerebrovascular segmentation, namely CESAR, with the ability to tackle feature granularity and image style heterogeneity issues. Specifically, a coarse-to-fine architecture is implemented to refine cerebrovascular segmentation in an iterative manner. An automatic feature selection module is proposed to selectively fuse global long-range dependencies and local contextual information of cerebrovascular structures. A style self-consistency loss is then introduced to explicitly align diverse styles of TOF-MRA images to a standardized one. Extensive experimental results on the COSTA dataset demonstrate the effectiveness of our CESAR network against state-of-the-art methods. We have made 6 subsets of COSTA with the source code online available, in order to promote relevant research in the community.

Automatic classification of retinal arteries and veins plays an important role in assisting clinicians to diagnosis cardiovascular and eye-related diseases. However, due to the high degree of anatomical variation across the population, and the presence of inconsistent labels by the subjective judgment of annotators in available training data, most of existing methods generally suffer from blood vessel discontinuity and arteriovenous confusion, the artery/vein (A/V) classification task still faces great challenges. In this work, we propose a multi-scale interactive network with A/V discriminator for retinal artery and vein recognition, which can reduce the arteriovenous confusion and alleviate the disturbance of noisy label. A multi-scale interaction (MI) module is designed in encoder for realizing the cross-space multi-scale features interaction of fundus images, effectively integrate high-level and low-level context information. In particular, we also design an ingenious A/V discriminator (AVD) that utilizes the independent and shared information between arteries and veins, and combine with topology loss, to further strengthen the learning ability of model to resolve the arteriovenous confusion. In addition, we adopt a sample re-weighting (SW) strategy to effectively alleviate the disturbance from data labeling errors. The proposed model is verified on three publicly available fundus image datasets (AV-DRIVE, HRF, LES-AV) and a private dataset. We achieve the accuracy of 97.47%, 96.91%, 97.79%, and 98.18% respectively on these four datasets. Extensive experimental results demonstrate that our method achieves competitive performance compared with state-of-the-art methods for A/V classification. To address the problem of training data scarcity, we publicly release 100 fundus images with A/V annotations to promote relevant research in the community.

Accurate estimation and quantification of the corneal nerve fiber tortuosity in corneal confocal microscopy (CCM) is of great importance for disease understanding and clinical decision-making. However, the grading of corneal nerve tortuosity remains a great challenge due to the lack of agreements on the definition and quantification of tortuosity. In this paper, we propose a fully automated deep learning method that performs image-level tortuosity grading of corneal nerves, which is based on CCM images and segmented corneal nerves to further improve the grading accuracy with interpretability principles. The proposed method consists of two stages: 1) A pre-trained feature extraction backbone over ImageNet is fine-tuned with a proposed novel bilinear attention (BA) module for the prediction of the regions of interest (ROIs) and coarse grading of the image. The BA module enhances the ability of the network to model long-range dependencies and global contexts of nerve fibers by capturing second-order statistics of high-level features. 2) An auxiliary tortuosity grading network (AuxNet) is proposed to obtain an auxiliary grading over the identified ROIs, enabling the coarse and additional gradings to be finally fused together for more accurate final results. The experimental results show that our method surpasses existing methods in tortuosity grading, and achieves an overall accuracy of 85.64% in four-level classification. We also validate it over a clinical dataset, and the statistical analysis demonstrates a significant difference of tortuosity levels between healthy control and diabetes group. We have released a dataset with 1500 CCM images and their manual annotations of four tortuosity levels for public access. The code is available at: https://github.com/iMED-Lab/TortuosityGrading.

The detection of retinal vessel is of great importance in the diagnosis and treatment of many ocular diseases. Many methods have been proposed for vessel detection. However, most of the algorithms neglect the connectivity of the vessels, which plays an important role in the diagnosis. In this paper, we propose a novel method for retinal vessel detection. The proposed method includes a dense dilated network to get an initial detection of the vessels and a probability regularized walk algorithm to address the fracture issue in the initial detection. The dense dilated network integrates newly proposed dense dilated feature extraction blocks into an encoder-decoder structure to extract and accumulate features at different scales. A multi-scale Dice loss function is adopted to train the network. To improve the connectivity of the segmented vessels, we also introduce a probability regularized walk algorithm to connect the broken vessels. The proposed method has been applied on three public data sets: DRIVE, STARE and CHASE_DB1. The results show that the proposed method outperforms the state-of-the-art methods in accuracy, sensitivity, specificity and also area under receiver operating characteristic curve.