Introduction: For patients with tumors near eloquent brain regions, awake craniotomy (AC) procedures are an important treatment option to maximize the extent of resection (and thus survival) while minimizing possible surgical side-effects. Use of AC, including intra-operative brain mapping by electrical stimulation, is particularly important for patients with low-grade glioma as gross total resection can substantially prolong survival. Initial evidence also shows that AC benefits from use of pre-operative functional magnetic resonance imaging (fMRI), to assist surgical decision-making. Here we report our initial experience with pre-operative fMRI of 22 glioma patients, testing the hypotheses that fMRI has a positive impact on surgical management, and that fMRI results agree with intra-operative mapping.
Methods: Pre-operative fMRI involved a battery of motor and language mapping tasks undertaken using a novel computerized tablet system, recently also modified for use in the operating room during AC. Intraoperative mapping results were video-recorded and used to validate fMRI results. Specifically, the degree of overlap between fMRI activations and intraoperative mapping was quantified by a spatial registration of the craniotomy window with MRI surface reconstructions.
Results: Thus far, 22 glioma patients (WHO grades I-III) between ages 18 to 70 (mean 41) have undergone preoperative fMRI. Sixteen patients underwent an AC with intraoperative mapping, 3 underwent surgical resection asleep, and 3 proceeded with alternative treatment options. In 19 patients, preoperative fMRI influenced surgical decisions by dictating the surgical approach and/or surgical technique. Functional MRI maps were validated within a 5 mm radius when compared with intraoperative mapping results.
Conclusions: Preoperative fMRI provides useful planning information with sufficient spatial accuracy to assist in the surgical management of glioma patients. This work provides rationale for conducting future multi-centre studies of our methodology to assess short-term and long-term patient outcomes.
Patient Care: Use of pre-operative fMRI and enhanced intra-operative brain mapping during awake craniotomy will provide more informed surgical decision-making and reduced behavioral side-effects from surgery
Learning Objectives: By the conclusion of the session, participants should be able to 1) describe the importance of early surgical intervention for patients with low-grade glioma; 2) discuss, in small groups, the potential usefulness of pre-operative functional magnetic resonance imaging (fMRI) to guide surgical decisions for patients with tumors near eloquent brain regions; and 3) identify specific ways that pre-operative fMRI can impact patient management.