In this project, I used 3D Slicer to annotate the fat tissue surrounding the pericardium of the heart from 3D heart CT scans. The objective was to accurately identify and label the pericardial fat tissue to create a well-annotated dataset for further analysis. This detailed annotation work was essential for enhancing the understanding of the relationship between pericardial fat and cardiac health, with potential implications for cardiovascular risk assessment and treatment strategies. The project required precision and careful attention to anatomical details, ensuring that the annotated data could support subsequent research and clinical applications.