Mapping Eloquent Brain with Functional MRI and DTI

The goal of surgery for brain tumors and epilepsy is maximal resection while respecting surrounding eloquent structures to avoid postoperative deficits. In order to preserve sensorimotor, language, and cognitive functions, delineating the patient-specific locations of structures supporting these networks is essential. Studies have shown that the identification of eloquent cortex in close proximity to the region of tumor or a resectable lesion is a strong predictor of worsened neurological outcome postoperatively or a limited extent of resection. Therefore, successful preoperative functional mapping of these regions, and their connections, can assist the neurosurgeon in preserving these fundamental abilities while maximizing extent of resection. This chapter reviews current evidence for using fMRI and DTI as noninvasive methods for mapping both eloquent cortex and critical white matter tracts in neurosurgical planning. Technical details and limitations of each method are discussed.