====== Three-dimensional intraoperative ultrasound for intradural spinal tumor ======

In 11 patients, [[Three-dimensional intraoperative ultrasound]] was performed before and after [[tumor resection]]. [[Intraoperative computed tomography]] (iCT) was used for automatic patient registration for spinal [[navigation]]; [[fiducial]]-based registration was performed in 1 case. The outlines of the vertebra were defined in preoperative image data by automatic mapping; risk and target structures were segmented manually; all these data were rigidly and if necessary non-rigidly registered with iCT. For 3D-iUS acquisition, tracked convex-shaped [[ultrasonic transducer]]s (contact surface: 29 x 10 mm; scanning frequency: 10-3.8 MHz or 13-5 MHz) were used.

Navigated 3D-iUS was successfully implemented in all cases; 3D-iUS [[dataset]]s were acquired and could be used as 3D image data for further navigation after iUS scanning. The 3D objects defined in preoperative image data, outlining the [[vertebra]], target and risk structures, could be visualized in the 3D-iUS data. Navigated 3D-iUS allowed to reliably evaluate the [[extent of resection]] in all cases and updating of [[navigation]], ensuring high navigational accuracy. The target registration error applying iCT-based automatic registration was 0.78 ± 0.23 mm. The effective dose for iCT was 0.11 ± 0.077 mSv for cervical and 1.75 ± 0.72 mSv for thoracic scans.

Using 3D-iUS can be successfully integrated into spinal navigation. Automatic registration applying low-dose iCT and non-linear image registration offer to display preoperative images in the same orientation as the 3D-iUS scan, as well as visualizing segmented structures in the navigated 3D-iUS data. This greatly facilitates image interpretation. Navigated 3D-iUS provides a possibility for navigation updating and immediate online quality control
((Saß B, Bopp M, Nimsky C, Carl B. Navigated 3-Dimensional Intraoperative
Ultrasound for Spine Surgery. World Neurosurg. 2019 Nov;131:e155-e169. doi:
10.1016/j.wneu.2019.07.188. Epub 2019 Jul 31. PubMed PMID: 31376550.
)).