Automated Polyp Segmentation Research Articles

Highlighted Diffusion Model as Plug-in Priors for Polyp Segmentation.

Automated polyp segmentation from colonoscopy images is crucial for colorectal cancer diagnosis. The accuracy of such segmentation, however, is challenged by two main factors. First, the variability in polyps' size, shape, and color, coupled with the scarcity of well-annotated data due to the need for specialized manual annotation, hampers the efficacy of existing deep learning methods. Second, concealed polyps often blend with adjacent intestinal tissues, leading to poor contrast that challenges segmentation models. Recently, diffusion models have been explored and adapted for polyp segmentation tasks. However, the significant domain gap between RGB-colonoscopy images and grayscale segmentation masks, along with the low efficiency of the diffusion generation process, hinders the practical implementation of these models. To mitigate these challenges, we introduce the Highlighted Diffusion Model Plus (HDM+), a two-stage polyp segmentation framework. This framework incorporates the Highlighted Diffusion Model (HDM) to provide explicit semantic guidance, thereby enhancing segmentation accuracy. In the initial stage, the HDM is trained using highlighted ground-truth data, which emphasizes polyp regions while suppressing the background in the images. This approach reduces the domain gap by focusing on the image itself rather than on the segmentation mask. In the subsequent second stage, we employ the highlighted features from the trained HDM's U-Net model as plug-in priors for polyp segmentation, rather than generating highlighted images, thereby increasing efficiency. Extensive experiments conducted on six polyp segmentation benchmarks demonstrate the effectiveness of our approach.

PVT2DNet: Polyp segmentation with vision transformer and dual decoder refinement strategy

Colorectal carcinoma is a prevalent malignancy worldwide. Accurate polyp segmentation, along with endoscopic resection, can significantly reduce its incidence and mortality. Most polyp segmentation neural networks are CNN-based and single decoder strategy architectures, which learn limited robust representations. In this paper, we propose a novel network with the vision transformer and dual decoder refinement strategy called PVT2DNet to overcome some limitations of current networks and achieve more precise automated polyp segmentation. The PVT2DNet adopts a pyramid vision transformer encoder and enhances the multi-level features with the context-enhanced module (CEM). Moreover, instead of directly feeding features into a single decoder, we introduce a dual partial cascaded decoder refinement strategy to excavate more informative polyp cues. Extensive experimentations on five widely adopted datasets demonstrate the proposed network outperforms other state-of-the-art on most metrics.

An Edge-Enhanced Network for Polyp Segmentation.

Colorectal cancer remains a leading cause of cancer-related deaths worldwide, with early detection and removal of polyps being critical in preventing disease progression. Automated polyp segmentation, particularly in colonoscopy images, is a challenging task due to the variability in polyp appearance and the low contrast between polyps and surrounding tissues. In this work, we propose an edge-enhanced network (EENet) designed to address these challenges by integrating two novel modules: the covariance edge-enhanced attention (CEEA) and cross-scale edge enhancement (CSEE) modules. The CEEA module leverages covariance-based attention to enhance boundary detection, while the CSEE module bridges multi-scale features to preserve fine-grained edge details. To further improve the accuracy of polyp segmentation, we introduce a hybrid loss function that combines cross-entropy loss with edge-aware loss. Extensive experiments show that the EENet achieves a Dice score of 0.9208 and an IoU of 0.8664 on the Kvasir-SEG dataset, surpassing state-of-the-art models such as Polyp-PVT and PraNet. Furthermore, it records a Dice score of 0.9316 and an IoU of 0.8817 on the CVC-ClinicDB dataset, demonstrating its strong potential for clinical application in polyp segmentation. Ablation studies further validate the contribution of the CEEA and CSEE modules.

Artificial intelligence based real time colorectal cancer screening study: Polyp segmentation and classification using multi-house database

PurposeThis work explores the potential of artificial intelligence (AI) for real-time colorectal cancer (CRC) screening. We utilized a multi-house dataset to achieve a three-step approach (i) automated polyp segmentation, (ii) analysis of machine learning (ML) for classification and (iii) to compare deep learning (DL) exploration for automated classification. MethodsTo achieve our objectives, we leveraged the CRPU-Net architecture for automated polyp segmentation within the multi-house colonoscopy images. Subsequently, a ML framework was employed for binary classification of the segmented regions. Feature extraction was performed using SIFT and ORB descriptors, followed by the feature fusion and dimensionality reduction through Principal Component Analysis (PCA) to create an optimal feature representation for classification. We further explored the potential of DL by investigating the use of SOTA and vision transformer (ViT) model. Additionally, we considered the development of a hybrid model (CRP-ViT) by potentially combining the ViT model with DL architectures. ResultsCRPU-Net achieved outstanding segmentation performance of 96.56% accuracy, 95.40% IoU, and 97.39% Dice coefficient. Additionally, the CRP-ViT model demonstrated promising results in binary classification of 96.59% accuracy, 96.38% sensitivity, 96.80% specificity, 96.82% precision, and 96.36% NPV. ConclusionThis study implemented CRPU-Net and CRP-ViT, AI systems designed for real-time polyp segmentation, and potential precancerous polyp classification. This comprehensive approach offers the potential to expedite colonoscopies, minimize unnecessary biopsies, improve patient care, and optimize healthcare resource allocation.

ADVANCING COLORECTAL POLYP DETECTION: AN AUTOMATED SEGMENTATION APPROACH WITH COLRECTSEG-UNET

Purpose: This study aimed to achieve two primary goals. First, we sought to develop a lightweight convolutional neural network (CNN) model, COLRECTSEG-UNet, for the purpose of automated polyp segmentation and localization. Second, we evaluated the generalizability of the proposed model by testing it on a proprietary colonoscopy image dataset (own dataset) in addition to a publicly available benchmark (CVC-ColonDB and Kvasir dataset). Methods: The COLRECTSEG-UNet architecture was employed to perform polyp segmentation. Subsequently, the model was trained and validated using an 80:20 data split from the CVC-ColonDB dataset. The efficacy of these data split was confirmed through [Formula: see text]-fold cross-validation. To elucidate the significance of each layer within the COLRECTSEG-UNet design, an ablation study was conducted. The performance of the model was assessed using various metrics on the CVC-ClinicDB, own dataset and Kvasir dataset during the testing phase. These metrics were then compared to those achieved by current state-of-the-art models and findings reported in recent literature. Results: When evaluated on the CVC-ClinicDB dataset, the COLRECTSEG-UNet model achieved outstanding accuracy of 0.9591, intersection over union (IoU) of 0.9299 and F1-Score of 0.9530. Similarly, impressive results were obtained on the own dataset, with accuracy, IoU and F1-Score values of 0.955, 0.9346 and 0.9539, respectively. Additionally, Kvasir dataset attained the accuracy, IoU and F1-Score of 0.9542, 0.9291 and 0.9565, respectively. These results demonstrate that the proposed COLRECTSEG-UNet outperforms the existing benchmark models and surpasses the performance reported in current literature. Conclusion: The implementation of COLRECTSEG-UNet as a lightweight model paves the way for its integration as a backend component within medical imaging system software. This has the potential to significantly aid gastroenterologists in clinical decision-making during interventions.

CGMA-Net: Cross-Level Guidance and Multi-Scale Aggregation Network for Polyp Segmentation.

Colonoscopy is considered the best prevention and control method for colorectal cancer, which suffers extremely high rates of mortality and morbidity. Automated polyp segmentation of colonoscopy images is of great importance since manual polyp segmentation requires a considerable time of experienced specialists. However, due to the high similarity between polyps and mucosa, accompanied by the complex morphological features of colonic polyps, the performance of automatic polyp segmentation is still unsatisfactory. Accordingly, we propose a network, namely Cross-level Guidance and Multi-scale Aggregation (CGMA-Net), to earn a performance promotion. Specifically, three modules, including Cross-level Feature Guidance (CFG), Multi-scale Aggregation Decoder (MAD), and Details Refinement (DR), are individually proposed and synergistically assembled. With CFG, we generate spatial attention maps from the higher-level features and then multiply them with the lower-level features, highlighting the region of interest and suppressing the background information. In MAD, we parallelly use multiple dilated convolutions of different sizes to capture long-range dependencies between features. For DR, an asynchronous convolution is used along with the attention mechanism to enhance both the local details and the global information. The proposed CGMA-Net is evaluated on two benchmark datasets, i.e., CVC-ClinicDB and Kvasir-SEG, whose results demonstrate that our method not only presents state-of-the-art performance but also holds relatively fewer parameters. Concretely, we achieve the Dice Similarity Coefficient (DSC) of 91.85% and 95.73% on Kvasir-SEG and CVC-ClinicDB, respectively. The assessment of model generalization is also conducted, resulting in DSC scores of 86.25% and 86.97% on the two datasets respectively.

Polypoid Lesion Segmentation Using YOLO-V8 Network in Wireless Video Capsule Endoscopy Images.

Gastrointestinal (GI) tract disorders are a significant public health issue. They are becoming more common and can cause serious health problems and high healthcare costs. Small bowel tumours (SBTs) and colorectal cancer (CRC) are both becoming more prevalent, especially among younger adults. Early detection and removal of polyps (precursors of malignancy) is essential for prevention. Wireless Capsule Endoscopy (WCE) is a procedure that utilises swallowable camera devices that capture images of the GI tract. Because WCE generates a large number of images, automated polyp segmentation is crucial. This paper reviews computer-aided approaches to polyp detection using WCE imagery and evaluates them using a dataset of labelled anomalies and findings. The study focuses on YOLO-V8, an improved deep learning model, for polyp segmentation and finds that it performs better than existing methods, achieving high precision and recall. The present study underscores the potential of automated detection systems in improving GI polyp identification.

Multi-level feature fusion network combining attention mechanisms for polyp segmentation

Clinically, automated polyp segmentation techniques have the potential to significantly improve the efficiency and accuracy of medical diagnosis, thereby reducing the risk of colorectal cancer in patients. Unfortunately, existing methods suffer from two significant weaknesses that can impact the accuracy of segmentation. Firstly, features extracted by encoders are not adequately filtered and utilized. Secondly, semantic conflicts and information redundancy caused by feature fusion are not attended to. To overcome these limitations, we propose a novel approach for polyp segmentation, named MLFF-Net, which leverages multi-level feature fusion and attention mechanisms. Specifically, MLFF-Net comprises three modules: Multi-scale Attention Module (MAM), High-level Feature Enhancement Module (HFEM), and Global Attention Module (GAM). Among these, MAM is used to extract multi-scale information and polyp details from the shallow output of the encoder. In HFEM, the deep features of the encoders complement each other by aggregation. Meanwhile, the attention mechanism redistributes the weight of the aggregated features, weakening the conflicting redundant parts and highlighting the information useful to the task. GAM combines features from the encoder and decoder features, as well as computes global dependencies to prevent receptive field locality. Experimental results on five public datasets show that the proposed method not only can segment multiple types of polyps but also has advantages over current state-of-the-art methods in both accuracy and generalization ability.

Boundary uncertainty aware network for automated polyp segmentation

Recently, leveraging deep neural networks for automated colorectal polyp segmentation has emerged as a hot topic due to the favored advantages in evading the limitations of visual inspection, e.g., overwork and subjectivity. However, most existing methods do not pay enough attention to the uncertain areas of colonoscopy images and often provide unsatisfactory segmentation performance. In this paper, we propose a novel boundary uncertainty aware network (BUNet) for precise and robust colorectal polyp segmentation. Specifically, considering that polyps vary greatly in size and shape, we first adopt a pyramid vision transformer encoder to learn multi-scale feature representations. Then, a simple yet effective boundary exploration module (BEM) is proposed to explore boundary cues from the low-level features. To make the network focus on the ambiguous area where the prediction score is biased to neither the foreground nor the background, we further introduce a boundary uncertainty aware module (BUM) that explores error-prone regions from the high-level features with the assistance of boundary cues provided by the BEM. Through the top-down hybrid deep supervision, our BUNet implements coarse-to-fine polyp segmentation and finally localizes polyp regions precisely. Extensive experiments on five public datasets show that BUNet is superior to thirteen competing methods in terms of both effectiveness and generalization ability.

ConvSegNet: Automated Polyp Segmentation From Colonoscopy Using Context Feature Refinement With Multiple Convolutional Kernel Sizes

Colorectal cancer occurs in the rectal of humans, and early detection has been proved to reduce its mortality rate. Colonoscopy is the standard used in detecting the presence of polyps in the rectal, and accurate segmentation of the polyps from colonoscopy images often provides helpful information for early diagnosis and treatment. Although existing deep learning models often achieve high segmentation performance when tested on the same dataset used in model training; still, their performance often degrades when applied to out-of-distribution datasets, leading to low model generalization or overfitting. This challenge is often associated with the quality of the features learnt from the input images. In this work, a novel Context Feature Refinement (CFR) module is proposed to address the challenge of low model generalization and segmentation performance. The CFR module is built to extract contextual information from the incoming feature map by using multiple parallel convolutional layers with progressively increasing kernel sizes. Using multiple parallel convolutions with different kernel sizes helped to extract more efficient multi-scale contextual information and thus enabled the network to effectively identify and segment small and fine details, as well as larger and more complex structures in the input images. Extensive experiments on three public benchmark datasets in CVC-ClinicDB, Kvasir-SEG, and BKAI-NeoPolyp showed that the proposed ConvSegNet model achieved jaccard, dice and F2 scores of 0.8650, 0.9177, and 0.9328 on CVC-ClinicDB, 0.7936, 0.8618, and 0.8855 on Kvasir-SEG, and 0.8045, 0.8747 and 0.8909 on BKAI-NeoPolyp datasets respectively. Also, an improved generalization performance was achieved by the ConvSegNet model, compared to the benchmark polyp segmentation models.

Attention-Guided Pyramid Context Network for Polyp Segmentation in Colonoscopy Images

Recently, deep convolutional neural networks (C-NNs) have provided us an effective tool for automated polyp segmentation in colonoscopy images. However, most CNN-based methods do not fully consider the feature interaction among different layers and often cannot provide satisfactory segmentation performance. In this paper, a novel attention-guided pyramid context network (APCNet) is proposed for accurate and robust polyp segmentation in colonoscopy images. Specifically, considering that different network layers represent the polyp in different aspects, APCNet first extracts multi-layer features in a pyramid structure, then utilizes an attention-guided multi-layer aggregation strategy to refine the context features of each layer by utilizing the complementary information of different layers. To obtain abundant context features, APCNet employs a context extraction module that explores the context information of each layer via local information retainment and global information compaction. Through the top-down deep supervision, our APCNet implements a coarse-to-fine polyp segmentation and finally localizes the polyp region precisely. Extensive experiments on two in-domain and four out-of-domain experiments show that APCNet is comparable to 19 state-of-the-art methods. Moreover, it holds a more appropriate trade-off between effectiveness and computational complexity than these competing methods.

Automated polyp segmentation based on a multi-distance feature dissimilarity-guided fully convolutional network.

Colorectal malignancies often arise from adenomatous polyps, which typically begin as solitary, asymptomatic growths before progressing to malignancy. Colonoscopy is widely recognized as a highly efficacious clinical polyp detection method, offering valuable visual data that facilitates precise identification and subsequent removal of these tumors. Nevertheless, accurately segmenting individual polyps poses a considerable difficulty because polyps exhibit intricate and changeable characteristics, including shape, size, color, quantity and growth context during different stages. The presence of similar contextual structures around polyps significantly hampers the performance of commonly used convolutional neural network (CNN)-based automatic detection models to accurately capture valid polyp features, and these large receptive field CNN models often overlook the details of small polyps, which leads to the occurrence of false detections and missed detections. To tackle these challenges, we introduce a novel approach for automatic polyp segmentation, known as the multi-distance feature dissimilarity-guided fully convolutional network. This approach comprises three essential components, i.e., an encoder-decoder, a multi-distance difference (MDD) module and a hybrid loss (HL) module. Specifically, the MDD module primarily employs a multi-layer feature subtraction (MLFS) strategy to propagate features from the encoder to the decoder, which focuses on extracting information differences between neighboring layers' features at short distances, and both short and long-distance feature differences across layers. Drawing inspiration from pyramids, the MDD module effectively acquires discriminative features from neighboring layers or across layers in a continuous manner, which helps to strengthen feature complementary across different layers. The HL module is responsible for supervising the feature maps extracted at each layer of the network to improve prediction accuracy. Our experimental results on four challenge datasets demonstrate that the proposed approach exhibits superior automatic polyp performance in terms of the six evaluation criteria compared to five current state-of-the-art approaches.

Automated polyp segmentation in colonoscopy images via deep network with lesion-aware feature selection and refinement

Clinically, proper polyp localization in colonoscopy images is crucial for early diagnosis and follow-up treatment of colorectal cancer. However, visual inspection is subjective, error-prone, and burdensome. In this paper, we propose an automated polyp segmentation method (named LFSRNet) to assist physicians to accurately segment polyps in colonoscopy images. The proposed LFSRNet follows an encoder–decoder architecture and benefits from two pivotal modules, i.e., a lesion-aware feature selection module (LFSM) and a lesion-aware feature refinement module (LFRM). Specifically, the LFSM selects lesion-aware features from the top-three highest layers of the encoder via a non-local attention mechanism and fuses them to generate the initial segmentation map for the decoder. The LFRM embedded in the decoder incorporates the guided context information and the output of LFRM from the adjacent higher layer to refine the lesion-aware features. Through top-down deep supervision, our LFSRNet can adaptively select and refine lesion-aware features and precisely localize the polyp regions. Experimental results on the Kvasir-SEG dataset (with the 80%–20% train-test split) show that LFSRNet is superior to six state-of-the-art competing methods and achieves a dice score of 0.9127, an intersection-over-union score of 0.8615, a sensitivity score of 0.9174, an accuracy score of 0.9728, an F2 score of 0.9123, and an MAE score of 0.0291, respectively. More extensive results show that LFSRNet also holds better generalization than competing methods when trained on the Kvasir-SEG dataset and tested on both the CVC-ClinicDB dataset and EndoScene dataset.

Convsegnet: Automated Polyp Segmentation from Colonoscopy Using Context Feature Refinement with Multiple Convolutional Kernel Sizes

Convsegnet: Automated Polyp Segmentation from Colonoscopy Using Context Feature Refinement with Multiple Convolutional Kernel Sizes

TGANet: Text-guided attention for improved polyp segmentation.

Colonoscopy is a gold standard procedure but is highly operator-dependent. Automated polyp segmentation, a precancerous precursor, can minimize missed rates and timely treatment of colon cancer at an early stage. Even though there are deep learning methods developed for this task, variability in polyp size can impact model training, thereby limiting it to the size attribute of the majority of samples in the training dataset that may provide sub-optimal results to differently sized polyps. In this work, we exploit size-related and polyp number-related features in the form of text attention during training. We introduce an auxiliary classification task to weight the text-based embedding that allows network to learn additional feature representations that can distinctly adapt to differently sized polyps and can adapt to cases with multiple polyps. Our experimental results demonstrate that these added text embeddings improve the overall performance of the model compared to state-of-the-art segmentation methods. We explore four different datasets and provide insights for size-specific improvements. Our proposed text-guided attention network (TGANet) can generalize well to variable-sized polyps in different datasets. Codes are available at https://github.com/nikhilroxtomar/TGANet.

Improving Polyp Segmentation in Colonoscopy using Deep Learning

Colorectal cancer is one of the major causes of cancer-related deaths globally. Although colonoscopy is considered as the gold standard for examination of colon polyps, there is a significant miss rate of around 22-28 %. Deep learning algorithms such as convolutional neural networks can aid in the detection and describe abnormalities in the colon that clinicians might miss during endoscopic examinations. The "MedAI: Transparency in Medical Image Segmentation" competition provides an opportunity to develop accurate and automated polyp segmentation algorithms on the same dataset provided by the challenge organizer. We participate in the polyp segmentation task of the challenge and provide a solution based on the dual decoder attention network (DDANet). The DDANet is an encoder-decoder-based architecture based on a dual decoder attention network. Our experimental results on the organizers' dataset showed a dice coefficient of 0.7967, Jaccard index of 0.7220, a recall of 0.8214, a precision of 0.8359, and an accuracy of 0.9557. Our results on unseen datasets suggest that deep learning and computer vision-based methods can effectively solve automated polyp segmentation tasks.

PolypSegNet: A modified encoder-decoder architecture for automated polyp segmentation from colonoscopy images

Colorectal cancer has become one of the major causes of death throughout the world. Early detection of Polyp, an early symptom of colorectal cancer, can increase the survival rate to 90%. Segmentation of Polyp regions from colonoscopy images can facilitate the faster diagnosis. Due to varying sizes, shapes, and textures of polyps with subtle visible differences with the background, automated segmentation of polyps still poses a major challenge towards traditional diagnostic methods. Conventional Unet architecture and some of its variants have gained much popularity for its automated segmentation though having several architectural limitations that result in sub-optimal performance. In this paper, an encoder-decoder based modified deep neural network architecture is proposed, named as PolypSegNet, to overcome several limitations of traditional architectures for very precise automated segmentation of polyp regions from colonoscopy images. For achieving more generalized representation at each scale of both the encoder and decoder module, several sequential depth dilated inception (DDI) blocks are integrated into each unit layer for aggregating features from different receptive areas utilizing depthwise dilated convolutions. Different scales of contextual information from all encoder unit layers pass through the proposed deep fusion skip module (DFSM) to generate skip interconnection with each decoder layer rather than separately connecting different levels of encoder and decoder. For more efficient reconstruction in the decoder module, multi-scale decoded feature maps generated at various levels of the decoder are jointly optimized in the proposed deep reconstruction module (DRM) instead of only considering the decoded feature map from final decoder layer. Extensive experimentations on four publicly available databases provide very satisfactory performance with mean five-fold cross-validation dice scores of 91.52% in CVC-ClinicDB database, 92.8% in CVC-ColonDB database, 88.72% in Kvasir-SEG database, and 84.79% in ETIS-Larib database. The proposed network provides very accurate segmented polyp regions that will expedite the diagnosis of polyps even in challenging conditions.

Automated polyp segmentation for colonoscopy images: A method based on convolutional neural networks and ensemble learning.

To automatically and efficiently segment the lesion area of the colonoscopy polyp image, a polyp segmentation method has been presented. An ensemble model of pretrained convolutional neural networks was proposed, using Unet-VGG, SegNet-VGG, and PSPNet. Firstly, the Unet-VGG is obtained by the first 10 layers of VGG16 as the contraction path of the left half of the Unet. Then, the SegNet-VGG is acquired by fine-tuned transfer learning VGG16, using the first 13 layers of VGG16 as the encoder of the SegNet and combined the original decoder of the SegNet. By adjusting the input size of the Unet-VGG, SegNet-VGG, and PSPNet, the preprocessed data can be correctly fed to the three network models. The three models are used as the basic trainer to train and segment the datasets. Based on the ensemble learning algorithm, the weight voting method is used to ensemble the segmentation results corresponding to single basic trainer. Both IoU and DICE similarity score were used to evaluate the segmentation quality for cvc300 with 300 images, CVC-ClinicDB with 612 images, and ETIS-LaribPolypDB with 196 images. From the experimental results, the IoU and DICE obtained by the proposed method for the cvc300 datasets can reach up to 96.16% and 98.04%, respectively, the IoU and DICE for the CVC-ClinicDB datasets can reach up to 96.66% and 98.30%, respectively, whereas the IoU and DICE for the ETIS-LaribPolypDB datasets can reach up to 96.95% and 98.45%, respectively. Evaluation of the IoU and DICE in our methods shows higher accuracy than previous methods. The experimental results show that the proposed method improved correspondingly in IoU and DICE compared to a single basic trainer. The range of improvement is 1.98%-6.38%. The proposed ensemble learning succeeds in automatic polyp segmentation, which potentially helps to establish more polyp datasets.