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Li Yu

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24 papers

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JBHI Journal 2026 Journal Article

FedHAC: Towards Robust Federated Multi-Lesion Segmentation With Heterogeneous Annotation Completeness

Yangyang Xiang
Nannan Wu
Li Yu
Kwang-Ting Cheng
Zengqiang Yan

Federated learning (FL) has emerged as a promising paradigm for collaborative medical image segmentation across institutions while preserving data privacy. Despite great efforts in addressing cross-client annotation heterogeneity FL, the prevalent annotation completeness heterogeneity in clinical practice due to varying diagnostic priorities has been completely overlooked, hindering the deployment of FL. In this paper, we formulate such a challenge and propose FedHAC for incompleteness-robust medical image segmentation. FedHAC consists of three modules, i. e. , Global Class Prototype Alignment (GCPA), Annotation Completeness-Aware Aggregation (ACAA), and GMM-driven Progressive Correction (GPC). Specifically, GCPA constructs a noise-resilient warm-up model through proximal-term regularization and prototype alignment. ACAA estimates client-wise annotation completeness and dynamically prioritizes high-quality clients. GPC groups clients into “noisy” and “clean” via GMM for progressive annotation correction to minimize error propagation. Extensive comparison experiments and ablation studies on public datasets demonstrate the superiority of FedHAC over state-of-the-art methods under various levels of annotation incompleteness.

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AAAI Conference 2026 Conference Paper

Learning to Tell Apart: Weakly Supervised Video Anomaly Detection via Disentangled Semantic Alignment

Wenti Yin
Huaxin Zhang
Xiang Wang
Yuqing Lu
Yicheng Zhang
Bingquan Gong
Jialong Zuo
Li Yu

Recent advancements in weakly-supervised video anomaly detection have achieved remarkable performance by applying the multiple instance learning paradigm based on multimodal foundation models such as CLIP to highlight anomalous instances and classify categories. However, their objectives may tend to detect the most salient response segments, while neglecting to mine diverse normal patterns separated from anomalies, and are prone to category confusion due to similar appearance, leading to unsatisfactory fine-grained classification results. Therefore, we propose a novel Disentangled Semantic Alignment Network (DSANet) to explicitly separate abnormal and normal features from coarse-grained and fine-grained aspects, enhancing the distinguishability. Specifically, at the coarse-grained level, we introduce a self-guided normality modeling branch that reconstructs input video features under the guidance of learned normal prototypes, encouraging the model to exploit normality cues inherent in the video, thereby improving the temporal separation of normal patterns and anomalous events. At the fine-grained level, we present a decoupled contrastive semantic alignment mechanism, which first temporally decomposes each video into event-centric and background-centric components using frame-level anomaly scores and then applies visual-language contrastive learning to enhance class-discriminative representations. Comprehensive experiments on two standard benchmarks, namely XD-Violence and UCF-Crime, demonstrate that DSANet outperforms existing state-of-the-art methods.

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AAAI Conference 2026 Conference Paper

LENS: Learning to Segment Anything with Unified Reinforced Reasoning

Lianghui Zhu
Bin Ouyang
Yuxuan Zhang
Tianheng Cheng
Rui Hu
Haocheng Shen
Longjin Ran
xiaoxin chen

Text-prompted image segmentation enables fine-grained visual understanding and is critical for applications such as human-computer interaction and robotics. However, existing supervised fine-tuning methods typically ignore explicit chain-of-thought (CoT) reasoning at test time, which limits their ability to generalize to unseen prompts and domains. To address this issue, we introduce LENS, a scalable reinforcement-learning framework that jointly optimizes the reasoning process and segmentation in an end-to-end manner. We propose unified reinforcement-learning rewards that span sentence-, box-, and segment-level cues, encouraging the model to generate informative CoT rationales while refining mask quality. Using a publicly available 3-billion-parameter vision–language model, i.e., Qwen2.5-VL-3B-Instruct, LENS achieves an average cIoU of 81.2% on the RefCOCO, RefCOCO+, and RefCOCOg benchmarks, outperforming the strong fine-tuned method, i.e., GLaMM, by up to 5.6%. These results demonstrate that RL-driven CoT reasoning significantly enhances text-prompted segmentation and offers a practical path toward more generalizable Segment Anything models (SAM).

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AAAI Conference 2025 Conference Paper

CP-DETR: Concept Prompt Guide DETR Toward Stronger Universal Object Detection

Qibo Chen
Weizhong Jin
Jianyue Ge
Mengdi Liu
Yuchao Yan
Jian Jiang
Li Yu
Xuanjiang Guo

Recent research on universal object detection aims to introduce language in a SoTA closed-set detector and then generalize the open-set concepts by constructing large-scale (text-region) datasets for training. However, these methods face two main challenges: (i) how to efficiently use the prior information in the prompts to genericise objects and (ii) how to reduce alignment bias in the downstream tasks, both leading to sub-optimal performance in some scenarios beyond pre-training. To address these challenges, we propose a strong universal detection foundation model called CP-DETR, which is competitive in almost all scenarios, with only one pre-training weight. Specifically, we design an efficient prompt visual hybrid encoder that enhances the information interaction between prompt and visual through scale-by-scale and multi-scale fusion modules. Then, the hybrid encoder is facilitated to fully utilize the prompted information by prompt multi-label loss and auxiliary detection head. In addition to text prompts, we have designed two practical concept prompt generation methods, visual prompt and optimized prompt, to extract abstract concepts through concrete visual examples and stably reduce alignment bias in downstream tasks. With these effective designs, CP-DETR demonstrates superior universal detection performance in a broad spectrum of scenarios. For example, our Swin-T backbone model achieves 47.6 zero-shot AP on LVIS, and the Swin-L backbone model achieves 32.2 zero-shot AP on ODinW35. Furthermore, our visual prompt generation method achieves 68.4 AP on COCO val by interactive detection, and the optimized prompt achieves 73.1 fully-shot AP on ODinW13.

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JBHI Journal 2025 Journal Article

ROXSI: Robust Cross-Sequence Semantic Interaction for Brain Tumor Segmentation on Multi-Sequence MR Images

Zhuo Kuang
Zengqiang Yan
Aly Abayazeed
Franca Wagner
Li Yu
Mauricio Reyes

Deep learning-based brain tumor segmentation on multi-sequence magnetic resonance imaging (MRI) has gained widespread attention due to its great potential in supporting brain disease diagnosis. Although, compared to single-sequence images, more information is available from multi-sequence MR images, noise and artifacts on any given MR sequence can result in significant performance degradations. As in clinical routine, it is not always possible to maintain high imaging quality across all MR sequences (e. g. , foreign bodies, ventricular drainage, shunts, involuntary patient motion, etc.), ensuring robustness of brain tumor segmentation from multi-sequence MR images is of great importance in clinical practice, but rarely explored. Accordingly, in this paper, we propose a robust brain tumor segmentation framework to mitigate the performance degradation caused by noise and artifacts on multi-sequence MR images. Specifically, based on semantic affinity, we propose a unique cross-sequence semantic interaction module (CSSI) to exploit inter-sequence correlations and extract noise-resilient features. In addition, we incorporate a batch-level covariance mechanism to suppress the redundant background information and improve the semantic enhancement effect of the CSSI module. In order to further improve segmentation performance, we also incorporate a sequence-level variance regularization mechanism to exploit sequence-specific features. To validate the robustness of ROXSI, brain tumor segmentation performance was evaluated under the existence of four common artifacts, at five different perturbation levels. We further performed a blinded qualitative clinical evaluation with two experienced neuro-radiologists, evaluating results from ROXSI and other popular CNN and Transformer-based segmentation models. Experimental results on two benchmark datasets demonstrate the superior robustness of ROXSI over other state-of-the-art segmentation methods.

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AAAI Conference 2025 Conference Paper

Structural Pruning via Spatial-aware Information Redundancy for Semantic Segmentation

Dongyue Wu
Zilin Guo
Li Yu
Nong Sang
Changxin Gao

In recent years, semantic segmentation has flourished in various applications. However, the high computational cost remains a significant challenge that hinders its further adoption. The filter pruning method for structured network slimming offers a direct and effective solution for the reduction of segmentation networks. Nevertheless, we argue that most existing pruning methods, originally designed for image classification, overlook the fact that segmentation is a location-sensitive task, which consequently leads to their suboptimal performance when applied to segmentation networks. To address this issue, this paper proposes a novel approach, denoted as Spatial-aware Information Redundancy Filter Pruning (SIRFP), which aims to reduce feature redundancy between channels. First, we formulate the pruning process as a maximum edge weight clique problem (MEWCP) in graph theory, thereby minimizing the redundancy among the remaining features after pruning. Within this framework, we introduce a spatial-aware redundancy metric based on feature maps, thus endowing the pruning process with location sensitivity to better adapt to pruning segmentation networks. Additionally, based on the MEWCP, we propose a low computational complexity greedy strategy to solve this NP-hard problem, making it feasible and efficient for structured pruning. To validate the effectiveness of our method, we conducted extensive comparative experiments on various challenging datasets. The results demonstrate the superior performance of SIRFP for semantic segmentation tasks.

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JBHI Journal 2024 Journal Article

Boundary-Aware Gradient Operator Network for Medical Image Segmentation

Li Yu
Wenwen Min
Shunfang Wang

Medical image segmentation is a crucial task in computer-aided diagnosis. Although convolutional neural networks (CNNs) have made significant progress in the field of medical image segmentation, the convolution kernels of CNNs are optimized from random initialization without explicitly encoding gradient information, leading to a lack of specificity for certain features, such as blurred boundary features. Furthermore, the frequently applied down-sampling operation also loses the fine structural features in shallow layers. Therefore, we propose a boundary-aware gradient operator network (BG-Net) for medical image segmentation, in which the gradient convolution (GConv) and the boundary-aware mechanism (BAM) modules are developed to simulate image boundary features and the remote dependencies between channels. The GConv module transforms the gradient operator into a convolutional operation that can extract gradient features; it attempts to extract more features such as images boundaries and textures, thereby fully utilizing limited input to capture more features representing boundaries. In addition, the BAM can increase the amount of global contextual information while suppressing invalid information by focusing on feature dependencies and the weight ratios between channels. Thus, the boundary perception ability of BG-Net is improved. Finally, we use a multi-modal fusion mechanism to effectively fuse lightweight gradient convolution and U-shaped branch features into a multilevel feature, enabling global dependencies and low-level spatial details to be effectively captured in a shallower manner. We conduct extensive experiments on eight datasets that broadly cover medical images to evaluate the effectiveness of the proposed BG-Net. The experimental results demonstrate that BG-Net outperforms the state-of-the-art methods, particularly those focused on boundary segmentation.

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AAAI Conference 2024 Conference Paper

DTMFormer: Dynamic Token Merging for Boosting Transformer-Based Medical Image Segmentation

Zhehao Wang
Xian Lin
Nannan Wu
Li Yu
Kwang-Ting Cheng
Zengqiang Yan

Despite the great potential in capturing long-range dependency, one rarely-explored underlying issue of transformer in medical image segmentation is attention collapse, making it often degenerate into a bypass module in CNN-Transformer hybrid architectures. This is due to the high computational complexity of vision transformers requiring extensive training data while well-annotated medical image data is relatively limited, resulting in poor convergence. In this paper, we propose a plug-n-play transformer block with dynamic token merging, named DTMFormer, to avoid building long-range dependency on redundant and duplicated tokens and thus pursue better convergence. Specifically, DTMFormer consists of an attention-guided token merging (ATM) module to adaptively cluster tokens into fewer semantic tokens based on feature and dependency similarity and a light token reconstruction module to fuse ordinary and semantic tokens. In this way, as self-attention in ATM is calculated based on fewer tokens, DTMFormer is of lower complexity and more friendly to converge. Extensive experiments on publicly-available datasets demonstrate the effectiveness of DTMFormer working as a plug-n-play module for simultaneous complexity reduction and performance improvement. We believe it will inspire future work on rethinking transformers in medical image segmentation. Code: https://github.com/iam-nacl/DTMFormer.

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AAAI Conference 2024 Conference Paper

FedA3I: Annotation Quality-Aware Aggregation for Federated Medical Image Segmentation against Heterogeneous Annotation Noise

Nannan Wu
Zhaobin Sun
Zengqiang Yan
Li Yu

Federated learning (FL) has emerged as a promising paradigm for training segmentation models on decentralized medical data, owing to its privacy-preserving property. However, existing research overlooks the prevalent annotation noise encountered in real-world medical datasets, which limits the performance ceilings of FL. In this paper, we, for the first time, identify and tackle this problem. For problem formulation, we propose a contour evolution for modeling non-independent and identically distributed (Non-IID) noise across pixels within each client and then extend it to the case of multi-source data to form a heterogeneous noise model (i.e., Non-IID annotation noise across clients). For robust learning from annotations with such two-level Non-IID noise, we emphasize the importance of data quality in model aggregation, allowing high-quality clients to have a greater impact on FL. To achieve this, we propose Federated learning with Annotation quAlity-aware AggregatIon, named FedA3I, by introducing a quality factor based on client-wise noise estimation. Specifically, noise estimation at each client is accomplished through the Gaussian mixture model and then incorporated into model aggregation in a layer-wise manner to up-weight high-quality clients. Extensive experiments on two real-world medical image segmentation datasets demonstrate the superior performance of FedA3I against the state-of-the-art approaches in dealing with cross-client annotation noise. The code is available at https://github.com/wnn2000/FedAAAI.

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JBHI Journal 2024 Journal Article

FedIOD: Federated Multi-Organ Segmentation From Partial Labels by Exploring Inter-Organ Dependency

Qin Wan
Zengqiang Yan
Li Yu

Multi-organ segmentation is a fundamental task and existing approaches usually rely on large-scale fully-labeled images for training. However, data privacy and incomplete/partial labels make those approaches struggle in practice. Federated learning is an emerging tool to address data privacy but federated learning with partial labels is under-explored. In this work, we explore generating full supervision by building and aggregating inter-organ dependency based on partial labels and propose a single-encoder-multi-decoder framework named FedIOD. To simulate the annotation process where each organ is labeled by referring to other closely-related organs, a transformer module is introduced and the learned self-attention matrices modeling pairwise inter-organ dependency are used to build pseudo full labels. By using those pseudo-full labels for regularization in each client, the shared encoder is trained to extract rich and complete organ-related features rather than being biased toward certain organs. Then, each decoder in FedIOD projects the shared organ-related features into a specific space trained by the corresponding partial labels. Experimental results based on five widely-used datasets, including LiTS, KiTS, MSD, BCTV, and ACDC, demonstrate the effectiveness of FedIOD, outperforming the state-of-the-art approaches under in-federation evaluation and achieving the second-best performance under out-of-federation evaluation for multi-organ segmentation from partial labels.

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IJCAI Conference 2024 Conference Paper

From Optimization to Generalization: Fair Federated Learning against Quality Shift via Inter-Client Sharpness Matching

Nannan Wu
Zhuo Kuang
Zengqiang Yan
Li Yu

Due to escalating privacy concerns, federated learning has been recognized as a vital approach for training deep neural networks with decentralized medical data. In practice, it is challenging to ensure consistent imaging quality across various institutions, often attributed to equipment malfunctions affecting a minority of clients. This imbalance in image quality can cause the federated model to develop an inherent bias towards higher-quality images, thus posing a severe fairness issue. In this study, we pioneer the identification and formulation of this new fairness challenge within the context of the imaging quality shift. Traditional methods for promoting fairness in federated learning predominantly focus on balancing empirical risks across diverse client distributions. This strategy primarily facilitates fair optimization across different training data distributions, yet neglects the crucial aspect of generalization. To address this, we introduce a solution termed Federated learning with Inter-client Sharpness Matching (FedISM). FedISM enhances both local training and global aggregation by incorporating sharpness-awareness, aiming to harmonize the sharpness levels across clients for fair generalization. Our empirical evaluations, conducted using the widely-used ICH and ISIC 2019 datasets, establish FedISM's superiority over current state-of-the-art federated learning methods in promoting fairness. Code is available at https: //github. com/wnn2000/FFL4MIA.

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JBHI Journal 2024 Journal Article

MFTrans: Modality-Masked Fusion Transformer for Incomplete Multi-Modality Brain Tumor Segmentation

Junjie Shi
Li Yu
Qimin Cheng
Xin Yang
Kwang-Ting Cheng
Zengqiang Yan

Brain tumor segmentation is a fundamental task and existing approaches usually rely on multi-modality magnetic resonance imaging (MRI) images for accurate segmentation. However, the common problem of missing/incomplete modalities in clinical practice would severely degrade their segmentation performance, and existing fusion strategies for incomplete multi-modality brain tumor segmentation are far from ideal. In this work, we propose a novel framework named M $^{2}$ FTrans to explore and fuse cross-modality features through modality-masked fusion transformers under various incomplete multi-modality settings. Considering vanilla self-attention is sensitive to missing tokens/inputs, both learnable fusion tokens and masked self-attention are introduced to stably build long-range dependency across modalities while being more flexible to learn from incomplete modalities. In addition, to avoid being biased toward certain dominant modalities, modality-specific features are further re-weighted through spatial weight attention and channel-wise fusion transformers for feature redundancy reduction and modality re-balancing. In this way, the fusion strategy in M $^{2}$ FTrans is more robust to missing modalities. Experimental results on the widely-used BraTS2018, BraTS2020, and BraTS2021 datasets demonstrate the effectiveness of M $^{2}$ FTrans, outperforming the state-of-the-art approaches with large margins under various incomplete modalities for brain tumor segmentation.

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IJCAI Conference 2024 Conference Paper

Pointsoup: High-Performance and Extremely Low-Decoding-Latency Learned Geometry Codec for Large-Scale Point Cloud Scenes

Kang You
Kai Liu
Li Yu
Pan Gao
Dandan Ding

Despite considerable progress being achieved in point cloud geometry compression, there still remains a challenge in effectively compressing large-scale scenes with sparse surfaces. Another key challenge lies in reducing decoding latency, a crucial requirement in real-world application. In this paper, we propose Pointsoup, an efficient learning-based geometry codec that attains high-performance and extremely low-decoding-latency simultaneously. Inspired by conventional Trisoup codec, a point model-based strategy is devised to characterize local surfaces. Specifically, skin features are embedded from local windows via an attention-based encoder, and dilated windows are introduced as cross-scale priors to infer the distribution of quantized features in parallel. During decoding, features undergo fast refinement, followed by a folding-based point generator that reconstructs point coordinates with fairly fast speed. Experiments show that Pointsoup achieves state-of-the-art performance on multiple benchmarks with significantly lower decoding complexity, i. e. , up to 90~160× faster than the G-PCCv23 Trisoup decoder on a comparatively low-end platform (e. g. , one RTX 2080Ti). Furthermore, it offers variable-rate control with a single neural model (2. 9MB), which is attractive for industrial practitioners.

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IJCAI Conference 2024 Conference Paper

Unsupervised Anomaly Detection via Masked Diffusion Posterior Sampling

Di Wu
Shicai Fan
Xue Zhou
Li Yu
Yuzhong Deng
Jianxiao Zou
Baihong Lin

Reconstruction-based methods have been commonly used for unsupervised anomaly detection, in which a normal image is reconstructed and compared with the given test image to detect and locate anomalies. Recently, diffusion models have shown promising applications for anomaly detection due to their powerful generative ability. However, these models lack strict mathematical support for normal image reconstruction and unexpectedly suffer from low reconstruction quality. To address these issues, this paper proposes a novel and highly-interpretable method named Masked Diffusion Posterior Sampling (MDPS). In MDPS, the problem of normal image reconstruction is mathematically modeled as multiple diffusion posterior sampling for normal images based on the devised masked noisy observation model and the diffusion-based normal image prior under Bayesian framework. Using a metric designed from pixel-level and perceptual-level perspectives, MDPS can effectively compute the difference map between each normal posterior sample and the given test image. Anomaly scores are obtained by averaging all difference maps for multiple posterior samples. Exhaustive experiments on MVTec and BTAD datasets demonstrate that MDPS can achieve state-of-the-art performance in normal image reconstruction quality as well as anomaly detection and localization.

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JBHI Journal 2023 Journal Article

BATFormer: Towards Boundary-Aware Lightweight Transformer for Efficient Medical Image Segmentation

Xian Lin
Li Yu
Kwang-Ting Cheng
Zengqiang Yan

Objective: Transformers, born to remedy the inadequate receptive fields of CNNs, have drawn explosive attention recently. However, the daunting computational complexity of global representation learning, together with rigid window partitioning, hinders their deployment in medical image segmentation. This work aims to address the above two issues in transformers for better medical image segmentation. Methods: We propose a boundary-aware lightweight transformer (BATFormer) that can build cross-scale global interaction with lower computational complexity and generate windows flexibly under the guidance of entropy. Specifically, to fully explore the benefits of transformers in long-range dependency establishment, a cross-scale global transformer (CGT) module is introduced to jointly utilize multiple small-scale feature maps for richer global features with lower computational complexity. Given the importance of shape modeling in medical image segmentation, a boundary-aware local transformer (BLT) module is constructed. Different from rigid window partitioning in vanilla transformers which would produce boundary distortion, BLT adopts an adaptive window partitioning scheme under the guidance of entropy for both computational complexity reduction and shape preservation. Results: BATFormer achieves the best performance in Dice of 92. 84 $\%$, 91. 97 $\%$, 90. 26 $\%$, and 96. 30 $\%$ for the average, right ventricle, myocardium, and left ventricle respectively on the ACDC dataset and the best performance in Dice, IoU, and ACC of 90. 76 $\%$, 84. 64 $\%$, and 96. 76 $\%$ respectively on the ISIC 2018 dataset. More importantly, BATFormer requires the least amount of model parameters and the lowest computational complexity compared to the state-of-the-art approaches. Conclusion and Significance: Our results demonstrate the necessity of developing customized transformers for efficient and better medical image segmentation. We believe the design of BATFormer is inspiring and extendable to other applications/frameworks.

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JBHI Journal 2023 Journal Article

Cluster-Re-Supervision: Bridging the Gap Between Image-Level and Pixel-Wise Labels for Weakly Supervised Medical Image Segmentation

Zhuo Kuang
Zengqiang Yan
Huiyu Zhou
Li Yu

Weakly supervised learning, releasing deep learning from highly labor-intensive pixel-wise annotations, has gained great attention, especially for medical image segmentation. With only image-level labels, pixel-wise segmentation/localization usually is achieved based on class activation maps (CAMs) containing the most discriminative regions. One common consequence of CAM-based approaches is incomplete foreground segmentation, i. e. under-segmentation/false negatives. Meanwhile, suffering from relatively limited medical imaging data, class-irrelevant tissues can hardly be suppressed during classification, resulting in incorrect background identification, i. e. over-segmentation/false positives. The above two issues are determined by the loose-constraint nature of image-level labels penalizing on the entire image space, and thus how to develop pixel-wise constraints based on image-level labels is the key for performance improvement which is under-explored. In this paper, based on unsupervised clustering, we propose a new paradigm called cluster-re-supervision to evaluate the contribution of each pixel in CAMs to final classification and thus generate pixel-wise supervision (i. e. , clustering maps) for CAMs refinement on both over- and under-segmentation reduction. Furthermore, based on self-supervised learning, an inter-modality image reconstruction module, together with random masking, is designed to complement local information in feature learning which helps stabilize clustering. Experimental results on two popular public datasets demonstrate the superior performance of the proposed weakly-supervised framework for medical image segmentation. More importantly, cluster-re-supervision is independent of specific tasks and highly extendable to other applications.

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IJCAI Conference 2023 Conference Paper

FedNoRo: Towards Noise-Robust Federated Learning by Addressing Class Imbalance and Label Noise Heterogeneity

Nannan Wu
Li Yu
Xuefeng Jiang
Kwang-Ting Cheng
Zengqiang Yan

Federated noisy label learning (FNLL) is emerging as a promising tool for privacy-preserving multi-source decentralized learning. Existing research, relying on the assumption of class-balanced global data, might be incapable to model complicated label noise, especially in medical scenarios. In this paper, we first formulate a new and more realistic federated label noise problem where global data is class-imbalanced and label noise is heterogeneous, and then propose a two-stage framework named FedNoRo for noise-robust federated learning. Specifically, in the first stage of FedNoRo, per-class loss indicators followed by Gaussian Mixture Model are deployed for noisy client identification. In the second stage, knowledge distillation and a distance-aware aggregation function are jointly adopted for noise-robust federated model updating. Experimental results on the widely-used ICH and ISIC2019 datasets demonstrate the superiority of FedNoRo against the state-of-the-art FNLL methods for addressing class imbalance and label noise heterogeneity in real-world FL scenarios.

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AAAI Conference 2022 Conference Paper

Imbalance-Aware Uplift Modeling for Observational Data

Xuanying Chen
Zhining Liu
Li Yu
Liuyi Yao
Wenpeng Zhang
Yi Dong
Lihong Gu
Xiaodong Zeng

Uplift modeling aims to model the incremental impact of a treatment on an individual outcome, which has attracted great interests of researchers and practitioners from different communities. Existing uplift modeling methods rely on either the data collected from randomized controlled trials (RCTs) or the observational data which is more realistic. However, we notice that on the observational data, it is often the case that only a small number of subjects receive treatment, but finally infer the uplift on a much large group of subjects. Such highly imbalanced data is common in various fields such as marketing and medical treatment but it is rarely handled by existing works. In this paper, we theoretically and quantitatively prove that the existing representative methods, transformed outcome (TOM) and doubly robust (DR), suffer from large bias and deviation on highly imbalanced datasets with skewed propensity scores, mainly because they are proportional to the reciprocal of the propensity score. To reduce the bias and deviation of uplift modeling with an imbalanced dataset, we propose an imbalance-aware uplift modeling (IAUM) method via constructing a robust proxy outcome, which adaptively combines the doubly robust estimator and the imputed treatment effects based on the propensity score. We theoretically prove that IAUM can obtain a better bias-variance trade-off than existing methods on a highly imbalanced dataset. We conduct extensive experiments on a synthetic dataset and two real-world datasets, and the experimental results well demonstrate the superiority of our method over state-of-the-art.

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JBHI Journal 2022 Journal Article

Symmetry-Aware Deep Learning for Cerebral Ventricle Segmentation With Intra-Ventricular Hemorrhage

Yineng Hua
Zengqiang Yan
Zhuo Kuang
Hang Zhang
Xianbo Deng
Li Yu

Cerebral ventricles are one of the prominent structures in the brain, segmenting which can provide rich information for brain-related disease diagnosis. Unfortunately, cerebral ventricle segmentation in complex clinical cases, such as in the coexistence with other lesions/hemorrhages, remains unexplored. In this paper, we, for the first time, focus on cerebral ventricle segmentation with the presence of intra-ventricular hemorrhages (IVH). To overcome the occlusions formed by IVH, we propose a symmetry-aware deep learning approach inspired by contrastive self-supervised learning. Specifically, for each slice, we jointly employ the raw slice and the horizontally flipped slice as inputs and penalize the consistency loss between the corresponding segmentation maps in addition to their segmentation losses. In this way, the symmetry of cerebral ventricles is enforced to eliminate the occlusions brought by IVH. Extensive experimental results show that the proposed symmetry-aware deep learning approach achieves consistent performance improvements for ventricle segmentation in both normal ( i. e. without IVH) and challenging cases ( i. e. with IVH). Through evaluation of multiple backbone networks, we demonstrate the architecture-independence of the proposed approach for performance improvements. Moreover, we re-design an end-to-end version of symmetry-aware deep learning, making it more extendable to other approaches for brain-related analysis.

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JBHI Journal 2022 Journal Article

Uncertainty-Aware Deep Learning With Cross-Task Supervision for PHE Segmentation on CT Images

Zhuo Kuang
Zengqiang Yan
Li Yu
Xianbo Deng
Yineng Hua
Shuyun Li

Perihematomal edema (PHE) volume, surrounding spontaneous intracerebral hemorrhage (SICH), is an important biomarker for the presence of SICH-associated diseases. However, due to irregular shapes and extremely low contrast of PHE on CT images, manually annotating PHE in pixel-wise is time-consuming and labour intensive even for experienced experts, which makes it almost infeasible to deploy current supervised deep learning approaches for automated PHE segmentation. How to develop annotation-efficient deep learning to achieve accurate PHE segmentation is an open problem. In this paper, we, for the first time, propose a cross-task supervised framework by introducing slice-level PHE labels and pixel-wise SICH annotations, which are more accessible in clinical scenarios compared to pixel-wise PHE annotations. Specifically, we first train a multi-level classifier based on slice-level PHE labels to produce high-quality class activation maps (CAMs) as pseudo PHE annotations. Then, we train a deep learning model to produce accurate PHE segmentation by iteratively refining the pseudo annotations via an uncertainty-aware corrective training strategy for noise removal and a distance-aware loss for background compression. Experimental results demonstrate that, the proposed framework achieves a comparative performance with the fully supervised methods on PHE segmentation, and largely improves the baseline performance where only pseudo PHE labels are used for training. We believe the findings from this study of using cross-task supervision for annotation-efficient deep learning can be applied to other medical imaging applications.

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JBHI Journal 2021 Journal Article

Deep Learning Methods for Lung Cancer Segmentation in Whole-Slide Histopathology Images—The ACDC@LungHP Challenge 2019

Zhang Li
Jiehua Zhang
Tao Tan
Xichao Teng
Xiaoliang Sun
Hong Zhao
Lihong Liu
Yang Xiao

Accurate segmentation of lung cancer in pathology slides is a critical step in improving patient care. We proposed the ACDC@LungHP (Automatic Cancer Detection and Classification in Whole-slide Lung Histopathology) challenge for evaluating different computer-aided diagnosis (CADs) methods on the automatic diagnosis of lung cancer. The ACDC@LungHP 2019 focused on segmentation (pixel-wise detection) of cancer tissue in whole slide imaging (WSI), using an annotated dataset of 150 training images and 50 test images from 200 patients. This paper reviews this challenge and summarizes the top 10 submitted methods for lung cancer segmentation. All methods were evaluated using metrics using the precision, accuracy, sensitivity, specificity, and DICE coefficient (DC). The DC ranged from 0. 7354 $\pm$ 0. 1149 to 0. 8372 $\pm$ 0. 0858. The DC of the best method was close to the inter-observer agreement (0. 8398 $\pm$ 0. 0890). All methods were based on deep learning and categorized into two groups: multi-model method and single model method. In general, multi-model methods were significantly better ( p $< $ 0. 01) than single model methods, with mean DC of 0. 7966 and 0. 7544, respectively. Deep learning based methods could potentially help pathologists find suspicious regions for further analysis of lung cancer in WSI.

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AAAI Conference 2021 Conference Paper

Joint Incentive Optimization of Customer and Merchant in Mobile Payment Marketing

Li Yu
Zhengwei Wu
Tianchi Cai
Ziqi Liu
Zhiqiang Zhang
Lihong Gu
Xiaodong Zeng
Jinjie Gu

In the mobile Internet era, mobile payment service becomes the foundation of inclusive finance, which brings convenience and security to people. Various marketing strategies are designed to encourage mobile payment activities by allocating incentives such as coupons or commissions to customers or merchants. We summary two significant issues. First, there is a phenomenon of mutual influence between merchants and customers, i. e. , bipartite influence issue, thus making the independent optimization of customers and merchants nonoptimal. Second, the redemptions of coupons are partially observed, as we can only observe that the customer redeems the coupon or not at a specific incentive value, but cannot observe that at other incentive value, i. e. , data censorship issue. In this paper, we propose a novel joint incentive optimization framework to address the above two issues. We propose to use a graph neural network to represent customers and merchants jointly by modeling the underlying bipartite influences. We then formulate the response model under the hazard regression setting and model the hazard rate with a piecewise nonlinear function to capture the changes of responses to different incentive values. Finally, we propose a linear programming method to allocate approximated optimal incentive values to customers and merchants in real-time. Extensive offline and online experimental results demonstrate the effectiveness of our proposed approach.

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AIIM Journal 2021 Journal Article

Practical fine-grained learning based anomaly classification for ECG image

Qing Cao
Nan Du
Li Yu
Ming Zuo
Jingsheng Lin
Nathan Liu
Erheng Zhong
Zizhu Liu

As a widely used vital sign within cardiology, Electrocardiography (ECG) provides the basis for assessing heart function and diagnosing cardiovascular diseases. Automated anomaly detection for ECG plays an important role in improving patient diagnosis efficiency and reducing healthcare costs. Practically, due to the limits of electronics support or the medical system setting, image is a more common format for large-scale ECG storage in most clinical institutions. To guarantee an automated ECG detection model's scalability and practicality in clinical applications, taking good advantage of ECG images is crucial. However, existing time digital-based discriminative models fail to learn from images effectively for two reasons. First of all, the signals recorded on images have much lower resolution and higher noise, which makes it impractical to extract precise ECG signals following existing techniques. Meanwhile, the differences between abnormal signals are usually subtle, and they may be overwhelmed by the noises in the images as well. Towards this end, we design a novel neural framework that can be directly applied to massive ECG images determining various types of cardiology abnormalities. It classifies fine-grained ECG images based on weakly supervised strategy, in which case only image-level labeling is required. By eliminating the need for part annotations, the proposed method can result in significant savings in annotation time and cost. The effectiveness of the method is demonstrated by experimental results on two real ECG datasets.

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JBHI Journal 2018 Journal Article

Robust Activity Recognition for Aging Society

Yi Chen
Li Yu
Kaoru Ota
Mianxiong Dong

Human activity recognition (HAR) is widely applied to many industrial applications. In the context of Industry 4. 0, driven by the same demand of machines' self-organizing ability, HAR can also be adopted in elderly healthcare. However, HAR should be adaptive to the application scenarios in elderly healthcare. In this paper, we propose a nonintrusive activity recognition method that can be applied to long-term and unobtrusive monitoring for elderlies. The method is robust to obstruction and nontarget object interference. Skeleton sequence is estimated from RGB images. Based on two activity continuity metrics, an interframe matching algorithm is proposed to filter nontarget objects. In order to make full use of spatial-temporal information, we propose a novel activity encoding method based on the interframe joints distances. A convolutional neural network is used to learn the distinguishing features automatically. A specific data augmentation method is designed to avoid the overfitting problem on small-scale datasets. The experiments are performed on two public activity datasets and a newly released noisy activity dataset (NAD). The NAD contains obstruction, nontarget object interference. The experimental results show that the proposed method achieves the state-of-the-art performance while only using one ordinary camera. The proposed method is robust to a realistic environment.

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