Performance of a tracked ultrasound navigation setup for pediatric tumor surgery: a phantom study

Purpose: Resecting pediatric tumors is often surgically challenging caused by insufficient tumor localization, due to limited visibility and palpability. Surgical navigation systems may potentially improve intraoperative tumor localization. This study evaluates the accuracy and precision of an in-house developed navigation setup using tracked ultrasound under standardized conditions. Methods: Bone surface-based registrations, using automatic bone segmentation on tracked ultrasound images, were conducted on phantoms to validate the performance of the in-house developed surgical navigation setup. Registration was conducted on different phantoms, consisting of tumors near bones of an extremity (n = 50), the pelvis (n = 5) and the thoracic wall (n = 5). In addition, the same registration framework was evaluated in the case of kidney tumors, where the kidney surface was used instead of the bone surface for registration. Target registration error (TRE) was used as the primary outcome measure. Results: For tumors localized with bone surface-based registration, the setup achieved a median TRE of 1.3 mm with an interquartile range (IQR) of 0.9–2.1 mm. The robustness of the bone surface registration method was demonstrated with consistent results across anatomical regions. For kidney tumor localization with kidney surface-based registration, the setup achieved a median TRE of 3.3 mm with an IQR of 2.7–3.6 mm. Conclusion: Under controlled circumstances, the navigation setup demonstrated reproducible < 2 mm accuracy for tumor localization using the bone surface registration. For kidney tumors, the navigation setup showed < 4 mm accuracy. These findings establish a performance benchmark that can guide interpretation of larger inaccuracies encountered during clinical use and support future development toward clinical implementation.