The intraoperative portable CT scanner-based spinal navigation: a viable option for instrumentation in the region of cervico-thoracic junction.

PURPOSE: Innovative intraoperative imaging modalities open new horizons to more precise image acquisition and possibly to better results of spinal navigation. Planning of screw entry points and trajectories in this prospective study had been based on intraoperative imaging obtained by a portable 32-slice CT scanner. The authors evaluated accuracy and safety of this novel approach in the initial series of 18 instrumented surgeries in anatomically complex segment of cervico-thoracic junction. METHODS: We report on the single-institution results of assessment of anatomical accuracy of C5-T3 pedicle screw insertion as well as its clinical safety. The evaluation of total radiation dose and of time demands was secondary endpoint of the study. RESULTS: Out of 129 pedicle screws inserted in the segment of C5-T3, only 5 screws (3.9 %) did not meet the criteria for correct implant positioning. These screw misplacements had not been complicated by neural, vascular or visceral injury and surgeon was not forced to change the position intraoperatively or during the postoperative period. Quality of intraoperative CT imaging sufficient for navigation was obtained at all spinal segments regardless of patient´s habitus, positioning or comorbidity. A higher radiation exposition of the patient and 27 min longer operative time are consequences of this technique. CONCLUSIONS: The intraoperative portable CT scanner-based spinal navigation is a reliable and safe method of pedicle screw insertion in cervico-thoracic junction.

Intraoperative portable CT-scanner based spinal navigation--a feasibility and safety study.

BACKGROUND: Navigation based on an intraoperative CT scan is not a new approach to spinal instrumentation. Innovative intraoperative imaging technology, however, opens new horizons to more precise image acquisition as well as to further workflow. Planning of screw entry-points and trajectories in this study had been based on intraoperative imaging obtained by a portable 32-slice CT scanner. This prospective study evaluates feasibility, accuracy, and safety of this novel approach in an initial series of 85 surgeries. METHOD: Medical records and radiological materials of 82 patients who underwent the first 85 consecutive stabilisations were analysed. Incorrect screw position, medical and technical complications as well as availability of this procedure in particular spinal levels were the subject of evaluation. RESULTS: Out of 571 implants inserted in all spinal levels, only five screws (0.87 %) did not meet the criteria for correct implant position. These screw misplacements had not been complicated by neural, vascular or visceral injury and the surgeon was not forced to change the position intraoperatively or during the postoperative period. The quality of intraoperative CT imaging sufficient for navigation was obtained at all spinal segments regardless of a patient's habitus or positioning or comorbidity. CONCLUSION: Intraoperative portable CT scanner-based navigation seems to be an effective way of doing spinal instrumentation guidance. High precision of implant insertion confirms the preconditions of navigation usage during more complex surgeries at any level of the spine.

Absolute Pose Estimation of Central Cameras Using Planar Regions.

A novel method is proposed for the absolute pose estimation of a central 2D camera with respect to 3D depth data without the use of any dedicated calibration pattern or explicit point correspondences. The proposed method has no specific assumption about the data source: plain depth information is expected from the 3D sensing device and a central camera is used to capture the 2D images. Both the perspective and omnidirectional central cameras are handled within a single generic camera model. Pose estimation is formulated as a 2D-3D nonlinear shape registration task which is solved without point correspondences or complex similarity metrics. It relies on a set of corresponding planar regions, and the pose parameters are obtained by solving an overdetermined system of nonlinear equations. The efficiency and robustness of the proposed method were confirmed on both large scale synthetic data and on real data acquired from various types of sensors.