Computational Digital Pathology Lab

BII_Research-CIID-CDPL-2023

Research

The global shortage of pathologists and rising cancer incidences have strained healthcare resources, leading to delayed and inadequate patient care. Our AI-based digital pathology (AIDP) Programme addresses these challenges by providing fast, accurate, and accessible diagnostic tools. This prorgamme aims to overcome ecosystem data and infrastructure issues, lack of production pipelines, smalle and low quality database and poor scalability of AI diagnostic models across different sites. By establishing an AI-powered diagnostic solutions and developing necessary intellectual properties like A!HistoClouds and A!MagQC as demonstrated in Figure 1, we support AI model optimization and generalization, such as A!Prostate model. Additionally, creating a large-scale annotated DP database and standardized annotation schemes enhances the development and deployment of AI solutions in clinical settings.


Figure 1. AI-based Digital Pathology Diagnosis workflow and its components, showcasing the innovative approaches for improving diagnostic accuracy and efficiency in pathology. A) The A!MagQC highlights the transition from manual assessment of pathology slides, which is often tedious and subjective, to an automated approach. It emphasizes the importance of high-quality data in ensuring the accuracy of AI models for cytology and pathology. The panel shows how AI can identify quality issues affecting interpretations and diagnoses, making the process more efficient and accurate. B). The A!HistoClouds  demonstrates a cloud-based annotation solution for pathology. It supports various types of annotations, including normal tissue, benign disease, and malignant regions. The panel highlights the integration of multiple tools for streamlined image annotation, showcasing a significant increase in AI-generated annotations. This module facilitates collaborative efforts and enhances the efficiency of the annotation process through cloud-based technology. C). The A!Prostate model presents a cloud-based annotation solution specifically designed for prostate Gleason Grading. It employs convolutional neural networks (CNNs) to distinguish between different grades of prostate cancer, including stroma, benign, Gleason 3 - 5. The panel illustrates how this AI-driven solution provides detailed and accurate annotations, contributing to better diagnostic precision and improved patient outcomes.

Our AIDP program’s goals include Image Appearance Migration (IAM) for cytology/pathology samples, developing a framework for AI models such as A!Prostate for Gleason grading, and utilizing generative AI to reduce dependence on human annotations. We also plan to develop autonomous cycled reinforcement learning to improve AI model explainability and generalization. By validating clinical AI pathological diagnostic models through international deployment and local cross-validation, we ensure high performance and accuracy. Our collaboration with institutions like A*STAR, NUH, SGH, and TTSH allows us to develop a comprehensive digital pathology development and adoption platform, integrating AI with a real-world pathological database. This initiative promises to enhance healthcare efficiency, generate commercially appealing intellectual properties, and stimulate job creation and talent development, positioning Singapore as a leading hub for AI-based diagnostics.


Establishing a Comprehensive Pipeline for Medical-Class Digital Pathology Diagnostic Models

Figure 2. The development and validation workflow of the AI-based Digital Pathology Diagnosis system, highlighting the stages from initial development to clinical validation across multiple clinical centres. The workflow begins with the A!MagQC and A!HistoClouds, which are complete and ready for deployment. These modules ensure the quality of digital pathology images and facilitate efficient, cloud-based annotation, respectively. The A!Prostate model, specifically designed for prostate cancer diagnosis, is also ready for use, showcasing its capability to provide accurate and detailed annotations. It further illustrates ongoing development efforts for AI modules targeting other cancers, including lymphoma, gastric cancer, breast cancer, and colon cancer. These modules are in various stages of development, with some projects already started, as depicted by the annotated pathology images. The workflow culminates in a multicentre and clinical validation phase, involving multiple hospitals. This stage emphasizes the importance of clinical validation to ensure the reliability and accuracy of the AI-based system in real-world settings, ultimately aiming to enhance diagnostic precision and improve patient outcomes.

The establishment of a comprehensive pathological AIDP model development framework is essential to address the current gaps in standardized AI development pipelines across various diseases. Our innovative framework integrates sample digitalization, data annotation, general AI model optimization, generalization, and clinical validation processes, supported by advanced tools like A!HistoClouds and A!MagQC. This pipeline, spanning from sample preparation to clinical decision-making, includes standard operating protocols (SOPs) for quality control and optimized imaging solutions. Large-scale DP data annotation and server/cloud-based storage bridge the gap between biomedical research and AI application in pathology fields. Quality control (QC) and generalization are pivotal in this framework. A!MagQC ensures the consistency and reliability of image quality, transforming traditional subjective methods into objective, automated processes. This tool quantitatively assesses common image quality issues, ensuring high-quality data for AI model training and application and serving as a goalkeeper in the future clinical practices. A!HistoClouds, on the other hand, facilitates pathologist-AI interaction (PAI), tele-pathology, and assistive pathological diagnosis, accelerating data curation through faster semi-automatic annotation. The development of medical-class R&D pipelines, workflows, and iterative optimization protocols from local and international data flows enhances the generalizability and robustness of AI models, ensuring their applicability across diverse clinical settings. By integrating these advanced QC and generalization methods, our framework aims to produce reliable, efficient, and scalable AI diagnostic solutions, significantly improving healthcare outcomes.

 

Revolutionizing Quality Control in AI Digital Pathology: The A!MagQC System

Figure 3. A!MagQC ensures the quality of digital pathology images through automated quality control processes. The left side of the figure demonstrates the variations in sample preparation and the use of different scanners that can introduce inconsistencies in pathology images. These variations are depicted as inputs into the A!MagQC system. The top section contrasts traditional manual assessment methods with the automated approach provided by A!MagQC. Manual assessment is described as qualitative and descriptive, often tedious and subjective, with issues such as blurriness affecting the quality. In contrast, the A!MagQC system is shown to provide a quantitative and automatic approach, resulting in more efficient and accurate assessments. The right side of the figure showcases the transition from qualitative and subjective evaluations of H&E (Hematoxylin and Eosin) and TCT (ThinPrep Cytologic Test) slides to quantitative and automatic assessments. A!MagQC identifies quality issues such as focus, contrast, uniformity, artifacts, and saturation, ensuring that the data used for AI model training and diagnostics is of high quality.

We designed A!MagQC to revolutionize image quality assessment, transforming traditional subjective, manual, and qualitative glass-slide QC into an objective, automated, and quantitative system. By applying advanced image processing techniques, A!MagQC comprehensively evaluates digital pathology whole slide images (WSI) across five critical categories: i). Out of focus, ii). Contrast, iii). Saturation, iv). Texture uniformity, and v). Artifacts. An image patch is deemed “low quality” if A!MagQC detects two or more issues among these categories, subsequently assigning a quantitative score to determine the overall quality of each WSI. A!MagQC has demonstrated remarkable efficiency, significantly reducing annotation costs and manpower effort while ensuring optimal scanner performance. In our programme, A!MagQC will serve as the indispensable “goal-keeper” for our large-scale, high-quality annotated database, underscoring the pivotal role of quality control in AI digital pathology.

 

A!HistoClouds: Revolutionizing AI-Driven Pathological Annotation

We have developed A!HistoClouds, a user-friendly image annotation platform that integrates AI capabilities and Pathologist-AI interaction (PAI), enabling efficient online annotation and tele-pathology. As a cloud-based and local server-compatible solution, A!HistoClouds allows pathologists to work anytime, anywhere, and facilitates seamless collaboration. A!HistoClouds enhances the concept of PAI by bridging pathologists’ expertise and AI, serving as a key component in the evolution of online AI models. Demonstrated in the workflow, PAI refines AI models based on pathologists’ annotations. The platform supports well-defined annotation schemes tailored to different diseases, adhering to WHO/Association standards. Its AI model-agnostic design ensures compatibility with various AI diagnostic models, providing a holistic integration. Built with a human-centric approach, A!HistoClouds post-processes AI output into consumable visual information, streamlining the diagnostic process. The platform offers a highly interactive viewer, enabling pathologists to navigate large digital pathology images (gigapixel) smoothly. Using a pyramid image approach, similar to Google Maps, pathologists can dynamically view, zoom, and draw annotations on pathological images via the A!HistoClouds WSI viewer, enhancing both usability and efficiency.


Figure 4. A!HistoClouds emphasizes its role in fighting cancer by leveraging AI models and pathology images for enhanced diagnostics and analysis. The central image shows the A!HistoClouds interface, accessible on various devices, including smartphones and desktop computers. This interface allows users to view proprietary bright field and fluorescence virtual slide formats, perform annotations, and analyze results directly in their browser from any device. The top right corner depicts a researcher and a robotic assistant using A!HistoClouds to annotate and analyze pathology images. The cloud infrastructure in the middle signifies the cloud-based nature of the solution, enabling seamless access to data and computational resources. The bottom right corner shows a medical professional reviewing annotated prostate slides, highlighting the collaboration between AI and human expertise. The AI annotations are color-coded to indicate different tissue types and diagnostic features, enhancing the accuracy and efficiency of cancer diagnosis.

 

Enhancing AI Diagnostic Accuracy Through Adaptive Generalization Techniques – A!Prostate Model

Figure 5. The comprehensive overview of the AI-based Digital Pathology Diagnosis system’s performance and validation across various stages and conditions. A). Shows the input of original pathology images from various acquisition systems and the consistent output results generated by the our AI model, ensuring reliable performance across different imaging platforms. B). Displays the transformation of the original images into consistent AI-generated results, demonstrating the robustness of the AI model in handling diverse input sources. C). Presents a bar graph comparing the macro average F1 scores of different scanners, with and without IAM generalization techniques. The results indicate that generalization techniques significantly enhance the model’s performance across different scanners. D). Outlines the three phases of the validation process: Phase 1: Traditional microscopic examination; Phase 2: Whole slide image (WSI) examination without AI assistance; Phase 3: WSI examination with AI assistance, highlighting the improvement in diagnostic efficiency and accuracy with AI integration. E). Shows a bar graph of the quadratic weighted kappa scores across different pathologists and phases, illustrating the consistency and reliability of AI-assisted diagnostics. F). Depicts a box plot comparing the examination time per WSI for each pathologist across the three phases, showing a significant reduction in examination time with AI assistance. G). Illustrates a specific case of cancer screening and Gleason grading using the AI model. The AI’s output is compared with the ground truth (GT), showing a 100% true positive rate for cancer screening and a high quadratic weighted kappa score of 0.845 for Gleason grading. This panel also emphasizes the ongoing large-scale, multi-center validation efforts to further confirm the AI model’s effectiveness.

Development and training of our AI-enhanced solution began when scanned images were uploaded to A!HistoClouds, where clinical pathologists annotated regions of interest (ROIs) and assigned labels to them (stroma, normal glands, Gleason Pattern 3-5, for example in prostate diagnosis). After cropping the images into small patches and splitting the data into training and testing sets, we trained a convolutional neural network (CNN) using this training dataset to classify image patches into different label categories. On a per-image patch level, the sensitivity, specificity, positive predictive value, and negative predictive value were 93.0%, 92.7%, 96.3%, and 81.5%, respectively. We then visualized the prediction results on whole slide level by applying the model to the entire image. Comparing the generated heat maps and ground truth (pathologists’ annotations and Gleason scores), the predictions made by the A!Prostate model (https://www.nature.com/articles/s43856-024-00502-1) were well-matched with the pathologists’ diagnoses. For every different scanner brand, the digitization techniques and parameters are different. Therefore, the images of a single glass slide scanned by different scanners have varied appearances. To overcome this variation issue, we developed an adaptive solution by applying generalization techniques, named as Image Appearance Migration (IAM) to generate consistent results. Our strategy was to standardize images across these scanners and reduce image inconsistencies. Additionally, we further enhanced the generalizability of the models by enlarging the original training dataset using colour augmentation to simulate the appearance variations of different scanners during training. After applying generalization techniques, our AI models demonstrated increased accuracy and consistency among different scanners, potentially other variation in the upstream steps such as staining. Our experimental results indicate that our model is independent of the scanner hardware used, demonstrating its generalization ability across different scanning devices. For a video introduction, please refer to the YouTube: https://youtu.be/M8gPByfyQMU?si=19RwONOCYLVlSoAP  

 

 

Members

 Principal Investigator  YU Weimiao   |    [View Bio]  
 Senior Research Scientist  ONG Kok Haur  
 Research Scientist LU Haoda
 Research Scientist YUAN Chengxiang
 Senior Research Officer HUO Xinmi
 Senior Research Officer LI Longjie
 Research Officer PENG Aisha
 PhD Student YOO Sehwan
 Visiting Pathology Scientist
 CHEN Wanyuan

Selected Publications