Emerging role of functional brain MRI in low-grade glioma surgery

Learning objectives
1. To describe the use of functional MRI (fMRI) in cranial surgery planning for patients with low-grade gliomas (LGG).
2. To show the increasing importance of fMRI in the clinical setting.
Background
LGG include brain tumors classified by the World Health Organization as grade I and II. LGG typically affect younger, otherwise healthy individuals.
Whereas previously the preferred management strategy of LGG was one of watchful expectation, there is now evidence supporting radical surgery as a means of preventing malignant transformation and ensuring precise tumor grading.
FMRI can be used to map eloquent cortex areas, thus minimizing postoperative deficits and improving surgical performance.
Findings and procedure details
Patients diagnosed with low-grade gliomas located in eloquent brain areas undergo fMRI prior to surgery.
The exams are performed on a 3T MR system (Achieva TX, Philips Healthcare, Best, The Netherlands). Blood oxygen level dependent (BOLD) contrast axial images are acquired using a T2-weighted single-shot echo planar imaging (EPI) sequence. Silent word generation and finger tapping paradigms are included in the exam to pinpoint Broca and motor cortex areas. Language comprehension and visual tasks can be added to visualize Wernicke’s area or the visual cortex. Diffusion tensor imaging (DTI) is used to map nerve tract course relative to the tumour.
Conclusion
FMRI has proven its clinical utility in locating eloquent brain areas with relation to tumor site and has contributed useful information to the management and treatment of LGG.