Article
Intraoperative 3D ultrasound in neurosurgery – an alternative technique
Intraoperativer 3D-Ultraschall in der Neurochirurgie – eine alternative Methode
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Published: | April 11, 2007 |
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Outline
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Objective: Ultrasound image quality has improved dramatically in recent years. The key to using intraoperative ultrasound images with neuronavigation was the development of an 3D-ultrasound system. Since the first results were published in 2002 it has become a real alternative for intraoperative imaging. However only few neurosurgical centres are familiar with 3D-IUS. There is a lack of information about usability, stability and accuracy of the system. The aim of the paper is the presentation of our experience with 45 patients.
Methods: For navigation support, a freehand 3D ultrasound workstation was used consisting of a standard personal computer containing a video grabber card in combination with an optical tracking system (NDI Polaris) and an ultrasound device (Siemens G 60 S). Preoperative 3D-MRI data were acquired with an 1, 5 Tesla magnet unit (Siemens, Germany). In cases with tumor localisation near the circuit of Willis an TOF-MRA (time of flight mRA) was implemented. All patients had an early postoperative MRI. The ultrasound probe worked directly in different depths (6-12cm). 3D-Power Doppler and 3D ultrasound datasets were obtained by the transdural route, after dural incision and at the end of the operation as well. The tracked microscope was used as a pointer to define tumor remnants.
Results: Up to November 2006, 45 patients were included in the study. The 3D ultrasound navigator was successful and robust in all patients. The accuracy of the US-navigator was generally 0.8 mm; the FFE was at least 1, 3 mm. The expenditure of time for one 3D-IUS datasets is with 2-5 minutes which is fast enough for intraoperative condition. Maximum brain shift was detected in all cases in a range from 1 to 12 mm. In gliomas the hyperechoic zone could detected and removed with 3D-IUS using iterative technique. Except for one, both the last 3D-IUS and the postoperative MRI demonstrated the same resection result of tumor remnants (95%) in all patients. Operative strategy was changed to more radical resection after 3D-IUS in seven patients (35%). In vascular malformations and hemangioblastomas, 3D rendering of the vessels with Power Doppler allows additional information about feeders and draining vessels for resection control and operative approach.
Conclusions: Up to November 2006, 45 patients were included in the study. The 3D ultrasound navigator was successful and robust in all patients. The accuracy of the US-navigator was generally 0.8 mm; the FFE was at least 1, 3 mm. The expenditure of time for one 3D-IUS datasets is with 2-5 minutes which is fast enough for intraoperative condition. Maximum brain shift was detected in all cases in a range from 1 to 12 mm. In gliomas the hyperechoic zone could detected and removed with 3D-IUS using iterative technique. Except for one, both the last 3D-IUS and the postoperative MRI demonstrated the same resection result of tumor remnants (95%) in all patients. Operative strategy was changed to more radical resection after 3D-IUS in seven patients (35%). In vascular malformations and hemangioblastomas, 3D rendering of the vessels with Power Doppler allows additional information about feeders and draining vessels for resection control and operative approach.