3D Reconstruction of Wilms’ Tumor and Kidneys in Children: Feasibility and Usefulness

Introduction: Wilms’ tumor (WT), or nephroblastoma, is the most common type of malignant kidney tumor in children. The surgical phase is a key stage in WT management. The main objective of this study was to determine the feasibility of WT segmentation and 3D reconstruction. The secondary objective was to assess the usefulness of these 3D reconstructions in the surgical planning phase and in the selection of patients for nephronsparing surgery. Materials and Methods: 14 scans from 12 patients were manually or semi-automatically segmented by 2 teams using 3D Slicer software. 3D reconstructions were then generated from the segmented images. Inter-individual variability was measured based on the Dice index. The pre-chemotherapy scan (at diagnosis) and the post-chemotherapy scan (before surgery) were segmented for 2 patients in order to measure the tumor volume reduction. The utility of 3D reconstructions for the surgical planning phase was evaluated by 4 pediatric surgeons using a 5-point Likert scale. The possibility of undertaking nephron-sparing surgery was evaluated according to the criteria defined in the UMBRELLA SIOP-RTSG 2016 protocol. Results: Segmentation of the renal tumor, healthy kidney, pathological kidney, arterial and venous vascularization could be performed for all of the patients in this study. Urinary cavities segmentation could only be performed for 5 out of 14 scans that had a delayed acquisition phase. The mean time required to carry out these segmentations was 8.6 hours [3-15 hours]. The mean Dice index for all of the scans was 0.87 [0.83-0.91]. The mean Dice indices for each anatomical structure were 0.95 [0.91-0.97] for the renal tumor, 0.87 [0.69-0.96] for the pathological kidney, 0.95 [0.93-0.96] for the healthy kidney, 0.84 [0.74-0.91] for the arterial vascularization, and 0.77 [0.58-0.86] for the venous vascularization. All the surgeons who were interviewed agreed that the 3D reconstructions were realistic representations and useful for the surgical planning phase. The images reconstructed in 3D allowed most of the criteria defined by the Umbrella SIOP-RTSG 2016 protocol to be evaluated regarding the selection of patients who could benefit from a conservative surgery. Conclusion: Three-dimensional representation appears to assist surgeons with the surgical planning phase by allowing them to better anticipate the operative risks. 3D reconstructions can also be an additional tool to better select patients for nephron-sparing surgery. However, the manual or semi-automatic method used is very time-consuming, making it difficult for a routinely use. Developing techniques to automate this segmentation process, therefore, appears to be essential if surgeons and radiologists are to use it in daily practice.