Task-based and resting-state functional MRI in DLGG

Abstract

Since two decades, functional MRI (fMRI) using blood oxygenation level dependent (BOLD) signal has become the most popular imaging method to map cortical involvement during various tasks. This non-invasive technique is commonly used in clinical practice before neurosurgery and in cognitive neurosciences. Much technical and methodological efforts were conducted to improve fMRI feasibility and reliability. In patients referred for neurosurgical resection of diffuse low grade glioma, task-based as well as resting-state fMRI could be helpful to maximize treatment efficiency and safety by allowing a more extensive tumor resection and by limiting the risk of permanent neurological deficit. When compared to intraoperative electrical stimulation mapping (ESM), task-based fMRI of the sensorimotor system is convincing with a good reliability. When compared to WADA test, fMRI of the language system is reliable to determine hemispheric dominance. However, ESM reported discrepancies with task-based language fMRI at the local level. Regarding resting-state fMRI, even though it seems to represent a very promising technique, more validation studies are nonetheless needed before using this new method for surgical planning. In summary, besides methodological and behavioral differences across techniques, fMRI in clinical practice requires to fully master all aspects of fMRI, from image acquisition to processing, and be aware of various limitations to provide a fair and useful interpretation.