Feasibility and Accuracy of Robotic-Assisted Navigation for Thoracic Pedicle Screw Placement Using Ct-Like 3d Mri

Cadaveric Study To assess the feasibility and accuracy of robotic positioning of thoracic pedicle screws based on magnetic resonance imaging (MRI). Robotic-assisted navigation (RAN) has demonstrated enhanced precision in thoracic pedicle screw placement. Currently, preoperative computer tomography (CT) scanning is required, exposing patients to radiation—a particular concern for younger patients undergoing multilevel fusion surgery. CT-like three-dimensional (3D)-MRI sequences may offer a radiation-free alternative, but their application in thoracic pedicle screw placement remains unexplored. CT-like 3D-MRI scans of the thoracic spine were obtained in two human cadaveric specimens. A RAN system was employed to plan and guide 48 pedicle screws (bilateral screws in thoracic vertebrae T1-T12) using these MRI scans. Following the placement of the pedicle screws, post-procedure CT scans were obtained to evaluate the accuracy of screw positioning. Accuracy was assessed by comparing the actual placement to the pre-procedure plan (difference in millimetres) and via the Gertzbein-Robbins scale (GRS). A total of 48 thoracic pedicle screws were inserted robotically in two human specimens (T1-T12 bilaterally). Post-procedure CT scan evaluations revealed that all screws achieved an acceptable grade on the GRS (A or B). Specifically, 87.5% of the screws were classified as Grade A and 12.5% were classified as Grade B. The median deviations from the planned trajectory were 0.4mm in the axial (IQR: 0.0; 1.2 mm) and 0.05mm in the sagittal (IQR: −0.3; 0.3 mm) planes. This cadaveric study demonstrates that MRI-based RAN can accurately guide thoracic pedicle screw placement. The findings suggest MRI-based RAN could provide a radiation-free alternative for thoracic spine instrumentation, particularly beneficial for pediatric and adolescent patients.