Neuronavigation based on intraoperative 3D-ultrasound during tumor resection

Abstract

Introduction Intraoperative imaging such as ultrasound is beneficial for intraoperative orientation, detection of brain shift and resection control. A combination of preoperative MRI with intraoperative 3D-ultrasound (3D-iUS) may enhance the convenience of neuronavigation by adding intraoperative information. The aim of our study was to evaluate fusion accuracy, the benefit of 3D-iUS navigation for the extent of resection and the suitability of iUS for detection and capture of intraoperative brain shift. Methods A freehand 3D ultrasound navigation system consisting of a standard personal computer containing a video grabber card in combination with an optical tracking system (NDI Polaris) and a standard ultrasound device (Siemens Omnia) with a 5.0 MHz probe was used. 3D-iUS datasets were acquired after craniotomy, at different subsequent times of the procedure and overlayed with preoperative MRI. All patients underwent early postoperative 3D-MRI including contrast agent within 24 h after surgery. Results Acquisition of 3D-iUS and the fusion with preoperative MRI was successful in 22/23 patients. The expenditure of time was at least 5 minutes for one 3D-iUS dataset and was used three to seven times during surgery. The quality of ultrasound images was superior in cases of metastasis, meningeoma and angioma to those in malignant glioma. Brain shifting ranged from 2 to 25 mm depending on localisation and kind of tumor. A resection control was possible in 78%. Conclusion The introduction of 3D-ultrasound has increased the value of neuronavigation substantially, making it possible to update ultrasound scans several times during surgery and minimize the problem of brain shift. Configuration both the 3D-iUS based on a standard ultrasound system and the MR-navigation system is time- and especially cost-effective. Novel and user-friendly display techniques make it possible to perform faster and more intuitive image-guided surgery.