Image-Guided Brain Tumor Resection

Surgical treatment of primary brain tumors remains a considerable challenge for the neurosurgeon. Nonetheless, surgery is the mainstay of glioma therapy because it provides the means of obtaining absolute tissue diagnosis, mapping tumor margins, mechanical cytoreduction, and guidance of adjuvant therapy such as brachytherapy, gene therapy, or radiosurgery. Recent developments in computation technology have fundamentally enhanced the role of medical imaging, from diagnosis to computer-aided surgery. Today, computer-assisted methods provide real-time information for dynamic navigation, analysis, and inspection of three-dimensional (3-D) image structures for preoperative surgery, virtual surgery, and intraoperative localization. Kelly’s pioneering work to establish volumetric stereotactic resection techniques has provided a basis for assessing the benefits of surgical resection of deeply seated parenchymal tumors.1 These techniques allow for proper diagnosis and definitive resection of benign and circumscribed gliomas as well as for radical cytoreduction of the bulk of high-grade tumors. Advances in image-guided technology greatly enhance a surgeon’s ability to create a plan prior to surgery, to follow it during surgery, and to modify the surgical approach based on intraoperative information. Although extent of resection of gliomas has not been analyzed as an influence on outcome in a prospective randomized trial, recent studies suggest improved length of survival after aggressive surgical resection.2–7 Berger et al8 have demonstrated that the degree of resection and amount of residual tumor are significantly related to the incidence of recurrence and to the tumor grade at recurrence. In the past, the task of correlating preoperative and intraoperative imaging studies was left to surgeons and depended on their knowledge of human anatomy. Stereotaxy enabled neurosurgeons to effectively correlate preoperative images with the patient’s physical anatomy during the operation. Imageguidance technology allows the use of “frameless stereotaxy,” offering accuracy similar to that of stereotactic neurosurgery while obviating some of the limitations.9–10 This chapter reviews the use, advantages, and limitations of frameless image guidance for neurosurgical treatment of brain tumors using the optical digitizer. Image guidance for biopsy and minimally invasive resection of brain tumors is reviewed as is the use of this technology for the administration of adjuvant treatment. Finally, the steps of these procedures as conducted at the authors’ institution are described.