Three-dimensional ultrasonography navigation in spinal cord tumor surgery. Technical note

The authors describe the technical application of three-dimensional (3D) ultrasonography navigation in spinal cord tumor surgery. The spinal cord is a complex neurological structure in which there is the potential for causing neurological morbidity during tumor resection. Standard neuronavigation systems based on computed tomography or C-arm images are not adapted to tumor surgery in the spinal cord. Since 2004 the authors have been using a 3D ultrasonography-based neuronavigation system. During surgery, two-dimensional ultrasound images were acquired and reconstructed into 3D image data to assist in tumor resection. The navigation cameras read the position of a patient reference frame attached to a spinous process, the ultrasonography probe, and surgical instruments. Five- and 10-MHz phased-array ultrasonography probes equipped with optical tracking frames were used for image data acquisition. Spinal cord tumors were visualized using ultrasonography, and 3D ultrasonography-guided tumor biopsy sampling and resection were performed. The practice of attaching the reference frame to a spinous process adjacent to the spinal cord tumor, as well as performing image acquisition just before starting the resection, reduced the possible sources of inaccuracy. The technical application of a navigation system based on intraoperative 3D ultrasound image reconstruction seems feasible and may have the potential of improving functional outcome in association with spinal cord tumor surgery.