Detection and segmentation of lymphomas in 3D PET images via clustering with entropy-based optimization strategy

Purpose: Lymphoma detection and segmentation from PET images are critical tasks for cancer staging and treatment monitoring. However, it is still a challenge owing to the complexities of lymphoma PET data themselves, and the huge computational burdens and memory requirements for 3D volume data. In this work, an entropy-based optimization strategy for clustering is proposed to detect and segment lymphomas in 3D PET images. Methods: To reduce computational complexity and add more feature information, billions of voxels in 3D volume data are first aggregated into supervoxels. Then, such supervoxels serve as basic data units for further clustering by using DBSCAN algorithm, in which some new feature attributes based on physical spatial information and prior knowledge are proposed. In addition, more importantly, an entropy-based objective function is constructed to search the most appropriate parameters of DBSCAN to obtain the optimal clustering results by using a genetic algorithm. This step allows to automatically adapt the parameters to each patient. Finally, a series of comparison experiments among various feature attributes are performed. Results: 48 patient data are conducted, showing the combination of three features, supervoxel intensity, geographic coordinates and organ distributions, can achieve good performance and the proposed entropy-based optimization scheme has more advantages than the existing methods. Conclusion: The proposed entropy-based optimization strategy for clustering by integrating physical spatial attributes and prior knowledge can achieve better performance than traditional methods.