Three-tesla functional MR language mapping: comparison with direct cortical stimulation in gliomas

Area of Science:

• Neurosurgery
• Neuroradiology
• Neuro-oncology

Background:

• Preoperative language mapping is essential for patients with supratentorial gliomas to minimize the risk of language deficits after surgery.
• Functional MRI (fMRI) at 3 Tesla is a common non-invasive tool for this purpose, but its accuracy compared to direct cortical stimulation (DCS) requires further evaluation.

Purpose of the Study:

• To assess the accuracy of 3T fMRI in preoperative language mapping for supratentorial gliomas.
• To compare fMRI language mapping with intraoperative DCS.
• To identify factors contributing to discrepancies between fMRI and DCS.

Main Methods:

• Retrospective analysis of 40 glioma patients undergoing fMRI and DCS for language mapping.
• fMRI utilized three block-designed tasks: letter word generation, category word generation, and semantic association.
• DCS was performed during awake surgery, blinded to fMRI results, with a site-by-site comparison using a cortical grid.

Main Results:

• Language fMRI demonstrated a sensitivity of 37.1% and specificity of 83.4% when compared to DCS.
• Factors independently associated with fMRI false-positive results included astrocytoma subtype, tumor relative cerebral blood volume (rCBV) < 1.5, higher cortical rCBV, and proximity to the tumor (>0.1 cm).

Conclusions:

• Current preoperative fMRI techniques for language mapping in glioma patients have limitations and potential pitfalls.
• The accuracy of fMRI is further complicated in the presence of high-grade and hyperperfused tumors, highlighting the continued importance of DCS.