gms | German Medical Science

With improved preoperative diagnostic imaging, and more intricate surgical methods available, the need for navigation in neurosurgery has become more evident. Fusion of different preoperative imaging modalities allows more strategic preoperative planning, but in the setting of the operating room there is still the need for an intraoperative update during tumor resection. Online intraoperative ultrasound can now be incorporated into the navigation system.

Presurgical imaging (MRI, CT, functional MRI, MRI-angiography) was obtained. Planning was done on the Brainlab neuronavigation system. Intraoperative ultrasound was acquired with a 7 MHz sector scanner (Acuson), calibrated for the appropriate scanning depth. Intraoperative sonography was repeated during resection of the lesion to update the neuronavigational images, the preoperative MRI-image was rendered analogous to the ultrasound scanning plane and manual brain shift correction performed via cursors.

Thirty intracranial lesions including astrocytomas grade 1-3, oligodendroglioma, glioblastomas, meningiomas, metastases, malignant lymphoma, cysts, and cavernoma were operated with neuronavigational monitoring and integration of intraoperative sonography. In all cases ultrasound showed the lesions clearly, assessed the amount of residual tumor and allowed for brain shift correction.

Intraoperative sonography proved to be an important adjunct to the static preoperative imaging modalities by offering a fast, repeatable, non-invasive method of updating the neuronavigational images. Furthermore, it provides additional online vascular information on vessel displacement, vascularization, and flow dynamics by means of color duplex and doppler modes. Thus it enhances neuronavigation and allows for more safety and ease of the surgical procedure.