C-arm-based three-dimensional navigation: a preliminary feasibility study.
OBJECTIVE: With the new Siremobil Iso-C3D C-arm, three-dimensional (3D) datasets can be acquired intraoperatively in near-real time. Preliminary studies investigated the advantages of this system for depiction in joint and spinal surgery. Three-dimensional navigation seems feasible using the DICOM dataset of the Siremobil Iso-C3D in navigation devices. An experimental study was designed to investigate the feasibility and accuracy of this new technique. MATERIALS AND METHODS: After implantation of fiducial markers (titanium mini-screws, Leibinger), a Siremobil Iso-C3D C-arm with standard imaging options was used to acquire pre-interventional 3D datasets of the specimens. These isotropic voxel data were transferred via DICOM to a medivision navigation system using the spine module. After registration of the fiducials, a total of 20 pedicle screws were implanted (in 4 artificial-bone vertebral bodies and 6 cadaver vertebrae in situ) with the use of the navigation system in real-time mode. Post-interventionally, Iso-C3D and CT scans were obtained to control for implant position in the cadaver study. RESULTS: Fiducial marker implantation and registration require a special protocol to ensure correct identification and patient orientation in the DICOM dataset. The obtained accuracy was within 2 mm. Post-interventional imaging of the cadaveric vertebrae showed 10 of 12 screws to be correctly placed, with the other two in marginal intraosseous positions. CONCLUSIONS: Three-dimensional navigation with the Siremobil Iso-C3D data set is feasible, the accuracy being comparable to that of CT-based navigation and adequate for clinical interventions. Fiducial marker-based registration allows navigation of different bones in the same dataset without additional 3D scanning. This method is very useful as an additional tool in registration-free Iso-C3D-based navigation, since the navigation system allows the use of only one dynamic reference base (DRB).